Dissertationen zum Thema „Irrigation Practice“

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This paper defines concepts of capacity and capacity development for agricultural water management, and particularly the contributions made by ICID in this area in the recent past. Working from a theoretical framework of overlapping domains of capacity development ¿ the enabling environment, the organisational and the individual domains, with knowledge management as a cross-cutting theme ¿ the paper reviews previous work in the field and then summarises a range of case studies from the sector which illuminate key aspects of these different domains. The paper notes the need to accommodate a rapidly-changing context for agricultural water management to take account of the increasing demand for water resources in all sectors, and the consequent requirement for support of new approaches to capacity development. These new approaches emphasise the growing importance of authentic knowledge, internally-generated learning and self-development, whether at the level of the organisation or the individual. The paper also recognises the need for continuing and long-term support of capacity development, particularly in processes of organisational and institutional change, where there is no single set of guidelines or practices which will fit every situation. Specific directions for future work are suggested, including increased attention to monitoring and evaluation of capacity development, and closer links to emerging work on water governance.
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Thesis (M.S.) -- University of Maryland, College Park, 2005.
Thesis research directed by: Dept. of Plant Science and Landscape Architecture . Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Magister Artium - MA
The subject of rural development has been at the forefront of South Africa’s government discourse and policy. In post-apartheid South African rural development policy has paid significant attention to poverty alleviation, job creation and food security by attempting to commercialize agriculture in the former ‘homelands’. This has been mainly encouraged through agricultural programmes such as Masibambisane Rural Development Initiative (MRDI) and the Massive Food Production Programme (MFPP). To support these agricultural development programmes, the South African government has directed a significant amount of its public budget towards their development. However, literature suggests that to a large extent these agricultural programmes have not succeeded in improving the agricultural situation as well as livelihoods of rural dwellers in the former ‘homelands’. Despite the efforts made by the South African government, agriculture and field cultivation in rural areas continue to show a decline. Furthermore, many agricultural projects that have been initiated to improve the lives of rural people have been abandoned. This thesis investigates the interface between the actors that are involved in agricultural development projects in Mnquma Local Municipality in the former homeland of Transkei, Eastern Cape. Two irrigation schemes in Mnquma Local Municipality are interrogated, namely Ntuzenyandu Irrigation Scheme and Mirlees Masibambisane Irrigation Scheme, as case studies for this study. The main objective is to investigate the causes of dissonances between the actors that are involved in these agricultural projects, as well as how these dissonances influence the outcomes of agricultural projects in Mnquma Local Municipality. It is the micro-politics of development at the interface between the various actors that must be studied in order to gain a full and nuanced picture of why the irrigation schemes have faced challenges. This study uses the actor-oriented and social interface approach. The study identifies community politics, struggles over state allocated resources, power relations between the actors, lack of community involvement and a ‘discourse of blaming’ between the actors as key challenges that are hindering the success of these agricultural projects. It is hoped that this study can shed some important insights for policy makers on how to improve and implement state-funded agricultural projects that will be able to achieve government objectives and expectations of the rural people.

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This study is about the on-ground implementation of sustainable farm practices supported by policies and directives that form the core of the European Union’s sustainability policy. Its goal is to identify the blockers to effective policy implementation in order to improve the approach to sustainability in the agricultural sector. Exploring ways to engage local stakeholders in farm sustainability has been central to create a holistic understanding about the processes that drive practices in agriculture systems, and the extent to which these processes can be transformed. Sustainability in agriculture is a broad topic, hence this study focuses on one segment of sustainability namely the use and management of water resources in irrigated agriculture. The study’s final recommendations to improve policy design and interventions, however, are general and apply to the implementation of all sustainable farm practices. Practical effectiveness of EU policies and directives for sustainable agriculture is constrained by: a lack of evaluating criteria to measure policy impact and communicate progress; incentives for growers to commit to more than the minimum required, and continuous local renegotiation of proposed measures and programmes which have contributed to a weakening of initial policy proposals. This study demonstrates that policies serve different purposes for different people at different social and political levels. However, sustainability comes into practice on the farm, which is why farmers’ perspective about a sustainable agricultural sector and the proposed voluntary and mandatory policy measures is so important. Farmers’ perspectives are still missing elements in policy design for sustainable agriculture. Co-developing and testing technologies that are meant to deliver sustainability in practice, as well as farm decision support tools, are critical in engaging farmers and other local stakeholders in sustainability and to transform embedded practices and institutions. Collaboration across disciplines is also important to address environmental goals and farmers’ needs in order to extract substantial environmental benefits as well as a long term commitment from land managers in sustainability. This study shows that there are many insights to be gained and learnings to be extracted from scrutinizing policy interventions. It raises awareness about improving policy implementation by providing practical examples from case studies conducted in Spain and in Italy. These insights encourage the use of interdisciplinary approaches, including socio-technical approaches, for an integrated people and technology based perspective on natural resource management to better policy design and interventions and make sustainable agriculture real.

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This study is about the on-ground implementation of sustainable farm practices supported by policies and directives that form the core of the European Union’s sustainability policy. Its goal is to identify the blockers to effective policy implementation in order to improve the approach to sustainability in the agricultural sector. Exploring ways to engage local stakeholders in farm sustainability has been central to create a holistic understanding about the processes that drive practices in agriculture systems, and the extent to which these processes can be transformed. Sustainability in agriculture is a broad topic, hence this study focuses on one segment of sustainability namely the use and management of water resources in irrigated agriculture. The study’s final recommendations to improve policy design and interventions, however, are general and apply to the implementation of all sustainable farm practices. Practical effectiveness of EU policies and directives for sustainable agriculture is constrained by: a lack of evaluating criteria to measure policy impact and communicate progress; incentives for growers to commit to more than the minimum required, and continuous local renegotiation of proposed measures and programmes which have contributed to a weakening of initial policy proposals. This study demonstrates that policies serve different purposes for different people at different social and political levels. However, sustainability comes into practice on the farm, which is why farmers’ perspective about a sustainable agricultural sector and the proposed voluntary and mandatory policy measures is so important. Farmers’ perspectives are still missing elements in policy design for sustainable agriculture. Co-developing and testing technologies that are meant to deliver sustainability in practice, as well as farm decision support tools, are critical in engaging farmers and other local stakeholders in sustainability and to transform embedded practices and institutions. Collaboration across disciplines is also important to address environmental goals and farmers’ needs in order to extract substantial environmental benefits as well as a long term commitment from land managers in sustainability. This study shows that there are many insights to be gained and learnings to be extracted from scrutinizing policy interventions. It raises awareness about improving policy implementation by providing practical examples from case studies conducted in Spain and in Italy. These insights encourage the use of interdisciplinary approaches, including socio-technical approaches, for an integrated people and technology based perspective on natural resource management to better policy design and interventions and make sustainable agriculture real.

One-irrigation barleys were bred to be grown with only a single irrigation near planting time. To further our understanding of how to manage these new cultivars, two one - irrigation barley genotypes (Seco and 2 -22 -9) were grown at four seeding rates (20, 40, 60, and 80 lbs seed /A); four nitrogen rates (0, 50, 100, and 150 lbs N /A); two phosphorus rates (0 and 100 lbs P₂O₅ /A); four row spacings (6, 12, 18, and 24 inch); and three planting dates (Nov 19, Dec. 23, and Jan. 22). The optimum seeding rate, fertilizer rate, and row spacing were dependent on genotype and planting date. The optimum seeding rate was 40 to 60 lbs /A for Seco and 80 lbs /A for 2 -22 -9. An increase in seeding rate decreased kernel weight and kernel number per head but increased head number. A positive response to nitrogen fertilizer was not obtained due to the high levels of residual soil nitrogen at planting (20 ppm NO₃⁻N) except for the case of Seco at the Dec. 23 planting date. Phosphorus fertilizer increased yield only at the Nov. 19 planting date and if accompanied by 100 lbs N /A. Soil phosphorous levels were 2 ppm PO₄⁻P and a positive response was expected Kernel weight was not influenced by Nor P fertilizer. Kernel number per head increased with certain combinations of genotype and planting date. Head number decreased with N rate but increased with phosphorus. The optimum row spacing was 18 inches at the Nov. 19 planting and 12 inches for Seco at the Jan. 22 planting date. At other combinations of genotype and planting date, no differences in grain yield were detected due to row spacing. Kernel weight increased with row spacing at the Nov. 19 planting date; kernel number per head was generally not affected and, head number decreased with row spacing. The results of this study surest that any recommendations on how to grow one - irrigation barley are gross approximations because of variations due to year, planting date, and genotype.

Solum is a barley adapted to one or two irrigations but the grain produced is often low in test weight. Studies were conducted on two commercial farms near Maricopa and Coolidge in an effort to verify data from previous studies suggesting that delaying the first post-emergence irrigation until boot increases test weight compared to earlier irrigation, but does not affect yield. The irrigation treatments consisted of 1) two irrigations – planting and boot, or 2) three irrigations – planting, 5- to 6-leaf stage, and heading (grower standard). The irrigation treatments had no effect on grain yield, test weight, kernel weight, or lodging at either location, but delaying the second irrigation until boot reduced plant height at Coolidge. Despite the lack of positive results from these studies, applying the second irrigation at boot may still be preferable to earlier applications because of reduced plant height and the risk of lodging. We have not been able to measure a benefit from a third irrigation for Solum barley in these or previous studies.

Solum is a barley bred for reduced water use that tends to have low test weight. This is the second year of an experiment conducted at the Maricopa Agricultural Center to determine the effect of the number of irrigations and their timing on test weight and grain yield of Solum barley. A single irrigation resulted in low yield (2043 lbs/acre) and unacceptable test weight (45.2 lbs/acre). Two or three irrigations increased yield and test weight in most cases. Applying a second irrigation at the 1 node, 2-3 node, or boot stages resulted in yield of 2694, 2877, and 2670 lbs/acre and test weight of 48.5, 49.0, and 49.5 lbs/bu, respectively. Applying a second irrigation at boot and a third irrigation between flowering and soft dough resulted in an average yield of 3008 lbs/acre and an average test weight of 50.0 lbs/bu. Delaying the second irrigation of Solum barley until boot reduces the risk of lodging and low test weight, and results in high yields.

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The weather near heading is the overriding factor in disease development. Cultural practices may be partially effective in controlling Karnal bunt, but cannot eliminate the disease completely.

The herbicides used in lettuce have changed little in more than 30 years. Poast was registered for grass control in the 1980's although preemergent applications of Kerb, Balan and Prefar have been the principal herbicides used in lettuce production since the mid 1960's. Balan was changed from a 1.5 lb./gal. Emulsifiable concentrate to a 60% dry flowable formulation in the mid 80's, Kerb has always been a 50% wettable powder and Prefar is still a 4 lb./gal. emulsifiable concentrate. Growers are constantly changing cultural practices to improve production or to become more efficient. The change in one cultural practice can, and often does, effect other cultural practices. The use of sprinklers to establish lettuce has become increasingly widespread in the Yuma area over the past 20 years. Kerb and Prefar can be mechanically incorporated into shaped beds although both are commonly incorporated with irrigation water. The change in irrigation practices during stand establishment from furrow irrigation to sprinklers has effected the performance of both Kerb and Prefar. Balan is normally disced into the soil prior to bed formation and is not as effected by irrigation practices during stand establishment. Four tests are presented in this paper that help explain the effect of irrigation practices on the performance of Kerb and Prefar.

Sustainable Built Environments Senior Capstone Project
This paper examines Subsurface Drip Irrigation(SDI) as a solution to water conservation in landscape irrigation. This is a problem because of the drought that the southwestern United States is experiencing, and the amount of water that landscapes utilize and which is ultimately wasted due to inefficient practices. Subsurface drip irrigation represents a potential solution due to its high efficiency and water saving ability; however, there are some problems within it as a system. Utilizing a multiple case studies approach, this paper looked at three of the top irrigation companies, Rain Bird, Toro, and Netafim, and examined how they innovated to overcome the problems with SDI. Synthesizing the best and most effective practices from each company, a model for improving SDI was generated.

The development of small-scale surface-water irrigation facilities in rainfed agricultural regions is a necessary but problematic task. Whilst some academic literature recognises that water control problems are the locally specific outcomes of social and political histories and processes, this is yet to be adequately comprehended and internalised in irrigation policy discourse and its manifestations in state and NGO intervention practices, which too often seek standardised and generally applicable solutions to such problems. This thesis, through a detailed study of smallscale surface-water irrigation systems - three recent NGO-led, state-sanctioned lift irrigation interventions and four indigenous storage works - and historical and present-day social relations amongst three adivasi (tribal) communities in south-east Jharkhand State, examines this insight and its significance for policy. Present-day international irrigation policy discourse has shifted since the 1980s and 1990s from one which recognised the necessity of group-based small-scale irrigation development and thus sought to provide support to the resource poor, towards one which promotes smaller, noncommunal technologies, expects greater financial contributions from farmers, and thus implicitly favours relatively wealthier farmers. This ideological policy shift, promoted internationally and nationally under neo-liberalism, is legitimised by the perceived poor outcomes of irrigation development investments. In Jharkhand, blame is placed upon water-users whose organisation for irrigation system management is often lacking, yet such outcomes have been aided by the state - which has in innumerable ways failed to support farmers, and by NGOs' inability to monitor and self-critically analyse their own interventions. This thesis, by conceptualising irrigation and society as mutually constitutive rather than autonomous, demonstrates the potential viability of small-scale irrigation technologies and argues for the development of irrigation centred upon improving irrigation water access and system management for the resource poor majority, not just a minority. This thesis takes an anthropological and sociological approach to the study of irrigation and society, which provides balance to the otherwise dominant technocratic engineering and common property resources and new institutional economics approaches in contemporary irrigation management thinking. Emphasis is placed on the historical processes that determine irrigation resource access and rights, and on the formal and informal rules that create and reinforce unequal access to irrigation systems. Methodologically it favours a sociological-historical method; research was conducted combining ethnographic methods with physical field measurements and archival research. The sociotechnical approach to irrigation, utilised by Boelens and Mollinga, places centrally the concepts of control and power, allowing an exploration of the political dimensions of water control - normative (discourse), technical (infrastructure), organisational (management), socio-legal and socio-economic (access), whilst allowing consideration of irrigation systems' social dimensions - as social constructions, having social requirements for use, and having social effects. Such a perspective indicates the necessity of inclusive, group-based irrigation development interventions, focussed on communities in their entirety, integrating with their socio-productive systems, and striving for equitable outcomes. In the medium and long term this may aid system sustainability thus increasing total food production.

This study uses data from a special tabulation of the USDA Farm and Ranch Irrigation Survey to examine the relationship between farm size and adoption of a variety of water management practices across seven Colorado Basin states. Parametric (Cochran-Armitage trend test) and non-parametric (Goodman-Kruskal gamma) methods were used to estimate associations between farm size and adoption of water management practices, use of water management information, and participation in conservation programs. Farms were divided into five categories: small farms, medium farms, large farms and very large farms, based on their gross sales. In all seven states, very large farms relied on a greater number of different information sources for water management than small farms. The relationship between farm size and information source use was not always monotonic, however. Small farms were more likely to rely more on their neighbors and irrigation district staff for water management information. Large and very large farms relied on a more diverse set of information sources and relied more on privately provide sources, such as consultants. In very few cases was a public or private information source used by more than half of any group of farmers. There is no "one-stop shopping" for irrigation management information. Smaller farms were more likely to not have investigated ways to improve water or energy conservation practices in the previous five years. Farmers cited economic factors as the most important largest constraints on adoption of conservation investments. Larger farms were more likely to participate in government (federal, state, or local) other conservation programs. These farms, though, account for the greatest share of water use. Many smaller farms do not have control over the timing of their irrigation applications, but rather depend on irrigation districts to supply water "in turn." Extension messaging to improve irrigation timing may be more effective if they target irrigation district staff that control irrigation scheduling.

Planting date is an important consideration when growing small grain varieties under reduced water use conditions. The objective of this study is to document interactions of planting date and varieties grown with a single irrigation near planting. Field studies were conducted at the Maricopa Agricultural Center during the 1988, 1989, and 1990 growing seasons. Six barley, durum, and wheat varieties were compared at four planting dates from November to February. Early November or early December planting dates were optimum. The relative performance of the varieties differed depending on the year and planting date. The highest yielding varieties over most planting dates were Solum and 6-39-1-1 (barleys), Mexicali (durum), and B85-277A and M83-39-18 (wheats). Improvement of barley, durum, and wheat genotypes for reduced water use conditions continues at the University of Arizona, and notable progress in durum and wheat performance has been achieved recently.

Les pucerons sont des ravageurs importants des principales espèces fruitières en France, pêcher et pommier notamment. Dans le but de réduire l’usage des produits phytosanitaires, différentes alternatives sont envisagées pour contrôler les pucerons en verger. Nous avons commencé ce travail de thèse par une synthèse des différentes méthodes alternatives de contrôle envisageables et leur positionnement au cours des différentes étapes du cycle biologique du puceron. Puis nous avons étudié les effets de la modulation des caractéristiques de la plante hôte, via les pratiques culturales, sur l’abondance des pucerons. Notre étude se base sur l’hypothèse « Plant Vigor » qui énonce que les insectes phytophages sont plus performants sur les plantes ou les organes de forte vigueur. Par conséquent, sur nos deux dispositifs expérimentaux factoriels nous avons combiné des suivis dynamiques de croissance végétative et d’abondance de pucerons : Prunus persica - Myzus persicae (2 niveaux d’irrigation × 2 niveaux d’apport azoté) et Malus domestica - Dysaphis plantaginea (2 niveaux d’irrigation × 2 génotypes d’arbre). Les facteurs ont été choisis pour leur impact potentiel sur la croissance végétative et la qualité nutritionnelle de la plante hôte. Les expérimentations ont été menées sur de jeunes arbres en pot, ne portant pas de fruit. Au niveau du rameau, l’abondance des pucerons est positivement corrélée à la croissance végétative sur les deux systèmes étudiés. Sur pêcher, la relation disponibilité en azote et abondance de pucerons semble être médiée par le fort impact de l’azote sur la croissance végétative. L’effet négatif de la restriction hydrique sur l’abondance de pucerons ne semble pas lié à un impact sur la croissance végétative. Aussi sur le second système étudié : pommier-puceron cendré, nous avons choisi de faire varier les apports en eau et de travailler sur deux génotypes, pour tester la généricité de la réponse observée. A l’échelle du rameau, l’effet de la restriction hydrique sur l’abondance de pucerons est négatif pour un génotype et positif pour l’autre. Par contre à l’échelle de l’arbre, sur les deux génotypes l’abondance de pucerons est corrélée positivement à la croissance végétative et la restriction hydrique impacte négativement l’abondance de pucerons, ce qui suggère que la performance des pucerons est limitée sur les arbres en restriction hydrique par une autre composante que la vigueur de l’arbre. Ce travail de thèse montre que la restriction hydrique et le contrôle de la vigueur via les apports azotés peuvent s’avérer être des leviers pour le contrôle des pucerons en verger fruitier. Cependant les relations mises en évidence sont dépendantes du génotype, ainsi que de l’échelle d’analyse. Il reste à évaluer l’applicabilité de telles mesures sur des arbres en conditions de production, en prenant en compte notamment l’effet des restrictions hydrique et azotée sur la production fruitière
Aphids are major pests of important fruit trees in France, especially peach and appletrees. In order to reduce chemical use, various alternatives can be implemented for themanagement of aphids in orchards. This thesis starts by a review of the different alternativemanagement methods and their positioning at different aphid life cycle stages. Then our workfocuses on the study of the effects of modulation of host plant characteristics, through culturalpractices, on aphid abundance. Our study is based on the Plant Vigor Hypothesis which statesthat phytophagous insects are more performant on vigorous plant or organ. Thus, in theexperimental part we combined dynamic assessment of vegetative growth and aphid abundanceduring two factorial experiments: Prunus persica – Myzus persicae (2 levels of water supply ×2 levels of nitrogen supply) and Malus domestica – Dysaphis plantaginea (2 levels of watersupply × 2 tree genotypes). We chose those factors for their possible impact on vegetativegrowth and nutritional quality of the host plant. We conducted the experiments on young nonbearingpotted trees. At shoot scale, aphid abundance is positively correlated to vegetativegrowth for both studied systems. On peach tree, the positive impact of nitrogen availability onaphid abundance seems to be mediated by the strong positive impact of nitrogen on vegetativegrowth. The negative effect of water restriction on aphid abundance seems to be unrelated toan impact of water availability on vegetative growth. Thus on the second studied system: appletree – rosy apple aphid, we chose to vary water supply and to work on two genotypes to test thegenericity of the observed pattern. At shoot scale, water restriction has a positive effect on aphidabundance on one tree genotype and a negative effect on the other one, whereas at tree scalefor both tree genotypes aphid abundance is positively correlated to vegetative growth and waterrestriction negatively impacts aphid abundance. These results suggest that aphid performanceon water restricted trees is limited by another host plant characteristics than vegetative growth.This thesis shows that water restriction and vigour management through nitrogen fertilizationcan be implemented to manage aphids in fruit orchards. However, the patterns evidenced aredependent on tree genotype and on the scale of analysis. The applicability of these alternativemethods remains to be assessed in producing orchards, taking into account the effects of waterand nitrogen restrictions on fruit production

Analyses of possible synergies between energy recovery and water management are essential for achieving sustainable improvements in the performance of pressurized irrigation networks. Improving the energy efficiency of water systems by hydraulic energy recovery is becoming an inevitable trend for energy conservation, emissions reduction, and increases in profit margins. This Ph.D. research is focused on the proposal and development of an optimization methodology that improves energy efficiency in pressurized irrigation networks. To develop this methodology, the main objective of this Ph.D. thesis, the research is supported by secondary objectives. The first secondary objective overviews the state-of-the-art for different hydropower systems, paying attention to those systems in which residual energy can be considered for energy improvement. Furthermore, the need to analyze this energy improvement in pressurized irrigation networks is justified through enumerating the main advantages and disadvantages of these energy recoveries. This first objective establishes the contextualization stage of the thesis. The second part of this Ph.D. research, which develops the rest of the objectives, is called the procedural stage. This phase contains the analytical and experimental development of this research. The analytical phase develops the main steps of the optimization strategy. Each step comprises one methodology or method that is focused on the following objectives: ¿ To propose a methodology to determine the circulating flow over time in pressurized irrigation networks in any line depending on the agronomist intrinsic parameters of the established crops ¿ To develop a calibration strategy for the flow assignment in lines, which indicates the success of the proposed methodology ¿ To establish the energy balance as well as the involved energy terms to quantify the theoretical recoverable energy in pressurized water networks, particularly in irrigation networks ¿ To present a new methodology to maximize the recovered energy considering the actual feasibility to allocate pumps working as turbines (PATs) within pressurized water networks by using simulated annealing as a water management tool. The analytical phase is complemented with an intensive experimental campaign in two different PATs (radial and axial) in steady and unsteady flow conditions. The campaign regarding steady flow conditions enables the study of the efficiency variations in the machine as a function of the flow and rotational speed. The experimental analysis as well as the modification of the classical affinity laws allows one to determine the best efficiency line (BEL) and the best efficiency head (BEH) based on Suter parameters. Both lines enable modelers to establish the optimal rotational speed as a function of the flow during each instant to maximize the recovered energy. These new lines (BEL and BEH) should be incorporated within the optimization strategy, developing a procedure to recover energy as a function of the number of installed machines. Finally, to complement the developed analysis for the installation of the recovery systems in pressurized water systems, the unsteady flow in these facilities is also analyzed.
El desarrollo de los análisis de las posibles sinergias entre los sistemas de recuperación de energía y la gestión del agua es esencial, para poder lograr mejoras en la eficiencia energética de las redes de riego presurizadas a través de medidas sostenibles. La mejora de la eficiencia energética, mediante la recuperación de la energía hidráulica, se está convirtiendo en una tendencia inevitable para la conservación de la energía, la reducción de las emisiones de gases efecto invernadero y el aumento de los márgenes de beneficio en los sistemas de distribución de agua presurizados. Esta tesis doctoral está centrada en la propuesta y desarrollo de una metodología de optimización, la cual, mejore la eficiencia energética en redes de riego presurizadas. Para desarrollar esta metodología, objetivo principal de esta tesis, la investigación está basada en diferentes objetivos secundarios. El primer objetivo secundario, estudia el estado del arte en los diferentes sistemas hidroeléctricos, prestando atención a aquellos sistemas en los que, la energía residual puede ser tenida en cuenta para mejorar la eficiencia energética. La necesidad de analizar esta mejora energética en las redes de riego presurizadas, se justifica mediante la enumeración de las principales ventajas y desventajas de estos sistemas de recuperación tienen sobre los sistemas de distribución. Este primer objetivo, establece la etapa de contextualización de la tesis. La segunda parte de la tesis, denominada fase procedimental o de procedimiento, desarrolla el resto de los objetivos y contiene, el desarrollo analítico y experimental de esta investigación. La fase analítica desarrolla los principales bloques que forman la estrategia de optimización. Estos bloques de contenido están constituidos, cada uno de ellos, por una metodología desarrollada o método aplicado, cubriendo los siguientes objetivos: ¿ Proponer una metodología que determine el caudal circulante a lo largo del tiempo, en cualquier línea, en función de los parámetros intrínsecos agronómicos. ¿ Desarrollar una estrategia de calibración para la asignación de caudales en líneas, que demuestre la bondad de la metodología propuesta. ¿ Establecer el balance energético, así como los términos energéticos involucrados, para cuantificar la energía recuperable teórica en redes presurizadas, particularmente en redes de riego. ¿ Presentar una nueva metodología de maximización de energía recuperada donde la viabilidad de asignar bombas trabajando como turbinas (PATs) dentro de redes de distribución sea considerada, mediante el uso de la herramienta 'simulated annealing' en la gestión del agua. La fase analítica se complementa con el desarrollo de una campaña experimental en dos PATs diferentes (una de tipo radial y otra de tipo axial). Ambas máquinas han sido ensayadas en condiciones de flujo permanente y transitorio. El análisis experimental en condiciones de flujo permanente ha permitido estudiar la variación de la eficiencia de la máquina en función del caudal y de la velocidad de rotación de la misma. Este análisis experimental, así como la modificación de las leyes clásicas de semejanza, han hecho posible la definición de la mejor línea de eficiencia (best efficiency line (BEL)) y la mejor eficiencia de altura recuperada (best efficiency head (BEH)). Ambas líneas están basadas en los parámetros de Suter, y permiten a los modeladores el establecimiento de la velocidad de giro óptima en función del caudal circulante en cada instante, maximizando la energía recuperada. Estas nuevas líneas (BEL y BEH) deben incorporarse a la estrategia de optimización, teniéndolas en cuenta a lo largo del proceso para recuperar energía en función del número de máquinas instaladas en el sistema. Finalmente, para complementar el análisis desarrollado de la instalación de sistemas de recuperación energética en redes de distribución, se ha anali
El desenvolupament de les anàlisis de les possibles sinergies entre els sistemes de recuperació d'energia i la gestió de l'aigua són essencials per a aconseguir millores en l'eficiència energètica de les xarxes de reg pressuritzades a través de mesures sostenibles. La millora de l'eficiència energètica, mitjançant la recuperació de l'energia hidràulica, s'està convertint en una tendència inevitable per a la conservació de l'energia, la reducció de les emissions de gasos efecte hivernacle i l'augment dels marges de benefici en els sistemes de distribució d'aigua pressuritzada. Aquesta tesi doctoral està centrada en la proposta i desenvolupament d'una metodologia d'optimització, la qual millore l'eficiència energètica en xarxes de reg pressuritzades. Per a desenvolupar aquesta metodologia, objectiu principal d'aquesta tesi, la recerca ha estat basada en diferents objectius secundaris. El primer objectiu secundari estudia l'estat de l'art en els diferents sistemes hidroelèctrics, centrant-se en aquells sistemes en els quals l'energia residual pot ser tinguda en compte per a millorar l'eficiència energètica. La necessitat d'analitzar aquesta millora energètica en les xarxes de reg pressuritzades es justifica mitjançant l'enumeració dels principals avantatges i desavantatges que aquests sistemes de recuperació tenen sobre els sistemes de distribució. Aquest primer objectiu estableix l'etapa de contextualització de la tesi. La segona part de la tesi, denominada fase procedimental o de procediment, desenvolupa la resta dels objectius i conté(, )el desenvolupament analític i experimental d'aquesta recerca. La fase analítica desenvolupa els principals blocs que formen l'estratègia d'optimització. Aquests blocs de contingut estan constituïts cadascun d'ells per una metodologia desenvolupada o mètode aplicat, els quals cobreixen els següents objectius: ¿ Proposar una metodologia que determine el cabal circulant al llarg del temps, en qualsevol línia, en funció dels paràmetres intrínsecs agronòmics. ¿ Desenvolupar una estratègia de calibratge per a l'assignació de cabals en línies, que demostre la bondat de la metodologia proposada. ¿ Establir el balanç energètic, així com els termes energètics involucrats, per a quantificar l'energia recuperable teòrica en xarxes pressuritzades, particularment en xarxes de reg. ¿ Presentar una nova metodologia de maximització d'energia recuperada, on la viabilitat d'assignar bombes treballant com a turbines (PATs) dins de xarxes de distribució siga considerada, mitjançant l'ús de l'eina "simulated annealing" en la gestió de l'aigua. La fase analítica es complementa amb el desenvolupament d'una campanya experimental en dues PATs diferents (una de tipus radial i una altra de tipus axial), les quals han sigut assajades en condicions de flux permanent i transitori. L'anàlisi experimental, en condicions de flux permanent, ha permès estudiar la variació de l'eficiència de la màquina en funció del cabal i de la velocitat de rotació de la mateixa. Aquesta anàlisi experimental, així com la modificació de les lleis clàssiques de semblança, han fet possible la definició de la millor línia d'eficiència (best efficiency line (BEL)) i la millor eficiència d'altura recuperada (best efficiency head (BEH)). Ambdues línies estan basades en els paràmetres de Suter i permeten als modeladors l'establiment de la velocitat de gir òptima, en funció del cabal circulant en cada instant, maximitzant l'energia recuperada. Aquestes noves línies (BEL i BEH) han d'incorporar-se a l'estratègia d'optimització, tenint-les en compte al llarg del procés per a recuperar energia en funció del nombre de màquines instal·lades en el sistema. Finalment, per a complementar l'anàlisi desenvolupada de la instal·lació de sistemes de recuperació energètica en xarxes de distribució, s'ha analitzat el règim transitori en aquests sistemes quan es produeix
Pérez Sánchez, M. (2017). METHODOLOGY FOR ENERGY EFFICIENCY IMPROVEMENT ANALYSIS IN PRESSURIZED IRRIGATION NETWORKS. PRACTICAL APPLICATION [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/84012
TESIS
Premiado

'Newhall' navel oranges on 'Carrizo' rootstock were planted in Mar. 1997 at the Citrus Agricultural Center. The objectives of this experiment were: i) to determine the effects of N rate and fertigation frequency for microsprinkler-irrigated navel oranges on tree N status, and crop yield and quality; and ii) to develop Best Management Practices which promote optimum tree growth and production while minimizing nitrate leaching. The trees are equipped with a microsprinkler irrigation system. The experiment is a randomized complete block factorial with N rates of 0, 0.15, 0.30, and 0.45 lb N/tree/year, and fertigation frequencies of weekly, monthly, and three times per year. Unfertilized control trees are also included in the experimental design. Each of the ten treatments is replicated five times. The trees were harvested for the first time in Feb. 2001. Fruit were processed through an automatic fruit sizer, and fruit from each plot were further evaluated for fruit quality. Although unfertilized control trees had lower leaf N content than fertilized trees, fruit yield and quality of controls was no lower than fertilized trees. Similarly, there were few statistically significant differences in fruit yield and quality between trees receiving different N rates and fertigation frequencies.

In order to tend to the world’s dwindling freshwater supplies, sustainable alternative methods need to be integrated in order to keep up with the world’s increasing demand. Reclaimed water (RW) is one of the sustainable methods adopted by some Floridian cities such as Tampa, Tallahassee, and St. Pete that provide an alternative water source for non-potable uses. However, despite this alleviating effect RW has on freshwater supplies, it is crucial to recognize the potential harm it poses on neighboring waterbodies due to the residual contaminants it still contains, including Nitrogen (N) and Phosphorous (P). As such, studying residents’ knowledge and behavior about RW provides an insight into certain behavioral trends that potentially explain elevated levels of N and P in certain waterbodies. This study surveyed households living in the vicinity of Joe’s Creek Watershed and are using RW in irrigation provided by Pinellas County Utilities Department (PC) and the City of St. Pete Water Resources Department (SP). After looking at these residents’ yard practices, no harmful behavioral trend was observed to explicate the health of neighboring waterbodies. RW users are aware of the irrigation regulations set for them. However, weakness in information communication between city and County officials and RW users on fertilizer use and regulations was recorded. It is recommended that the city of St. Pete revisits their loose regulations on RW and the irrigation schedule set for their customers. More outreach material on fertilizer application and regulations need to be made available and accessible to the public.

'Newhall' navel oranges on 'Carrizo' rootstock were planted in Mar. 1997 at the Citrus Agricultural Center. The objectives of this experiment were to i) determine the effects of N rate and fertigation frequency for microsprinkler-irrigated navel oranges on tree N status, and crop yield and quality; and ii) develop Best Management Practices which promote optimum tree growth and production while minimizing nitrate leaching. The trees are equipped with a microsprinkler irrigation system. The experiment is a randomized complete block factorial with N rates of 0, 0.15, 0.30, and 0.45 lb N/tree/year, and fertigation frequencies of weekly, monthly, and three times per year. Unfertilized control trees are also included in the experimental design. Each of the ten treatments is replicated five times. The trees were harvested in Jan. 2002. Fruit were processed through an automatic fruit sizer, and fruit from each plot were further evaluated for fruit quality. Leaf N concentration was responsive to N rate, but not to fertigation frequency. Leaf N in all fertilized plots was above tissue critical levels. Fruit yield in fertilized plots was higher than in unfertilized plots, but, in fertilized treatments, there was no significant effect of N rate or fertigation frequency on fruit yield or quality.

The main aim of this study was to assess the impact of the Best Management Practices (BMP) project on social and economic wellbeing at Zanyokwe Irrigation Scheme (ZIS) in central Eastern Cape Province. The BMP project is a knowledge-based initiative aimed at introducing management practices (mainly soft skills) in order to improve production and livelihoods in the study area. The study employed a survey to collect socio-economic data amongst farming households. The 2005 situation analysis, which was conducted amongst the same respondents before the introduction of the new practices allowed for comparisons in order to track changes or impacts after the implementation of the project. Also, the social and economic impact assessment (SEIA) framework was used to assess the impacts. The results of the impact assessment showed the BMP project to have an impact on social and economic well being of households. The skills introduced were in the areas of water management, agronomic practices, marketing and institutional arrangements. More than 90% indicated that there was improvement in agronomic practices and water management and 68% in marketing. More than half of farmers worked in their farms on a daily basis, which is a big change as none of the farmers worked during weekends in 2005. The average time spent on the farms also increased from four (in 2005) to seven hours (this investigation) on average per day. The BMP project also had a positive impact on social relationships and networks between farmers and the BMP project team as well as well as farmers and non-farmers. Land use intensity improved due to increases in acreage of main crops as well as cultivating at both seasons. More than 40% of farmers cropped their land at both seasons (winter and summer). In 2005, most of the land was fallow in winter. While some of the new practices introduced had a negative impact on input expenditures, the returns were positive. These extra efforts and expenditures resulted in improvement in incomes. Agricultural contribution to household income increased from 71% in 2005 to 81% in 2007. The increase in household incomes had a positive effect on poverty and food security status of households. The proportion of households earning incomes that are below poverty line dropped from 61% in 2005 to 38% in 2007. Changes in the diet of the households were noticed. In addition to the consumption of staples such as samp, maize meal and rice, people added a variety of vegetables. Own production was the main source of these vegetables as was indicated by 66% of respondents compared to only 25% in 2005. Food remained the main expenditure category though, as was the case in 2005. Improvements in marketing such as performing extra marketing functions and adopting a marketing strategy (collective action) also led to improvements in economic wellbeing.

To evaluate the strip tillage in organic bell pepper (Capsicum annuum L.) production as an integrated system for sustainable vegetable cropping two-years of field trials were conducted in 2011 and 2012. The field trials were conducted to determine the viability of strip tillage in conventional and organic bell pepper production systems by comparing plant growth, water status, and fruit yield to plastic mulch grown plants application under different irrigation regimes. The two-year field data demonstrated that organic pepper with strip tillage application was a viable combination that produced comparable yield to conventional plastic mulch system and utilized water more economically. In 2011 and 2013, strip-tilled rows and plastic mulched rows were used to evaluate the impact of tillage on soil hydraulic conductivity and water internal drainage characteristics. Results indicated that strip-tilled plots had significantly higher in-row penetration resistance compared to the plastic mulch system at depths up to 20 cm, but no differences between the systems were found for layers below 25 cm. In addition, there were no differences in hydraulic conductivity between strip tillage and plastic mulch in both study years over a 30-day period. Also, significant main effects were found for soil layer and time scale on hydraulic conductivity in the first 24 hour of the study in 2013. During field trials in 2011 and 2012, plant tissues were sampled for endophytic bacteria isolation and identification. Differences in endophytic bacteria were obtained among different production combinations. In 2013, endophytic bacteria isolates from 2011 and 2012 trials were re-inoculated to bell pepper grown in greenhouse to assess plant growth. Two Pseudomonas sp. and one Bacillus thioparans strain were screened to evaluate their affects on plant growth under both drought and non-drought conditions. After growth comparisons, the three endophytic strains were used to subsequently study the impacts of endophyte inoculation on regulating plant drought-linked gene expressions in 2014 by conducting real-time PCR. Results demonstrated that plant drought-linked genes, which especially involved plant ethylene biosynthesis, were significantly down-regulated after inoculating the endophytic bacterial strains.

Qui prendra ma terre ? L’Office du Niger, des investissements internationaux aux arrangements fonciers locaux.La crise alimentaire mondiale de 2008 a provoqué un mouvement d’investissements fonciers à grande échelle. En Afrique de l’Ouest, l’Office du Niger (ON) est un cas emblématique des aux investissements fonciers dans l’irrigation. 45 000 exploitations familiales y exploitent 100 000 ha de rizières sur lesquelles ils n’ont jamais obtenu de droits fonciers. Faute de capitaux, l’Etat malien a fait appel aux investisseurs, privés et publics, nationaux et étrangers, pour atteindre l’objectif d’un million d’ha irrigués visé depuis 1932. De nouvelles règles facilitent leur accès à la terre. L’arrivée des investisseurs et les risques d’accaparements ont donné le signal d’une course à la terre où les différents acteurs, investisseurs, paysans, petits et hauts responsables de l’Etat, mettent en oeuvre des arrangements fonciers informels.La thèse montre que ces arrangements ont leurs racines dans l’évolution historique du foncier. Elle analyse le développement des arrangements fonciers en tant que processus d’adaptation à des règles contraignantes ne permettant pas aux acteurs d’atteindre leurs objectifs. Trois types d’arrangements ont pu être identifiés : des arrangements coopératifs, des arrangements néo-coutumiers et des arrangements spéculatifs. A travers l’analyse des jeux d’acteurs, la thèse souligne l’importance du rôle des acteurs, mais aussi du contexte socio-politico-spatial dans la construction des arrangements fonciers
Who will take my land? The Office du Niger, international investments to local tenure arrangements.The 2008 global food crisis led to a wide dynamic of large scale investments in agriculture. In West Africa, the Office du Niger (ON) irrigation scheme is a significant example of such a dynamic of investment in agriculture. 45,000 family farmers grow rice on 100,000 hectares where they have never obtained property rights. Facing low national investment capacity and a significant decrease in the international development assistance, the Malian State launched an appeal to investors to reach the objective defined in the early 1930’s of one million hectares developed for irrigation. Investors were national or foreign investors from the private or public sectors. The State defined new rules to make their access to land easier. The risk of land grabbing linked to the arrival of new investors gave the signal for a rush to access to land in which different actors: investors, farmers, national or local officers, used informal arrangements.This research shows that these arrangements are historically rooted in the evolution of land management in the ON area. The main methodological contribution of this research is that arrangements are analyzed as a process that enables the different actors to adapt to binding rules, and finally to achieve their objectives. Three types of arrangements are described: cooperative arrangements, neo-customary arrangements, and speculative arrangements. By analyzing stakeholders’ games, this research highlights the importance of the actors’ positions and the socio-political context as key factors in the creation of new land arrangements

Técnicas de cultivo para adaptar la viticultura mediterránea al cambio climático La viticultura mediterránea se está viendo afectada por el cambio climático, lo que amenaza la tipicidad del vino y, por tanto, la sostenibilidad de la vitivinicultura. Los principales factores que se prevé que afecten al cultivo de la vid son la escasez de agua, los incrementos térmicos y el aumento de la concentración de dióxido de carbono en el aire, lo que influirá en la vid: i) adelantando su fenología, disociando así la maduración tecnológica y fenólica de la uva y ii) incrementando las necesidades hídricas del viñedo. Éste trabajo pretende evaluar los efectos de diferentes técnicas de cultivo para la adaptación de la viticultura mediterránea al cambio climático. Se realizaron tres experimentos en Valencia (España) estudiando los efectos de: 1) el riego deficitario controlado; 2) la arquitectura de los sistemas de conducción y 3) el manejo del dosel vegetal. Las principales respuestas evaluadas fueron la eficiencia en el uso del agua de los viñedos (EUA) y la composición de la uva. El experimento 1 se llevó a cabo durante tres campañas en un viñedo de Moscatel de Alejandría/161-49C regado por goteo con el objetivo de definir la estrategia de riego más sostenible para uva blanca en el levante español. Para ello, se ensayaron cuatro tratamientos: (i) Testigo, regado al 100% de la evapotranspiración del cultivo (ETc) durante toda la campaña; (ii) riego deficitario sostenido (SDI), regado al 50% del Testigo; (iii) déficit temprano (ED), donde se restringió el riego antes del envero, seguido de un 100% de ETc; y (iv) déficit tardío (LD), regado como el Testigo hasta el envero y posteriormente al 25% de la ETc hasta la vendimia. La producción en el ED y el LD se redujo en un 25 y 15% respectivamente en comparación a la del Testigo, mientras que la producción del SDI no difirió significativamente del Testigo ni de los tratamientos de ED y LD. Todos los tratamientos con riego deficitario mostraron efectos acumulativos en la productividad de las cepas como consecuencia de la reducción del número de racimos por sarmiento y del tamaño del racimo debido al menor tamaño de la baya. El experimento 2 pone de manifiesto que la respuesta a la minimización de la radiación interceptada por el dosel vegetal es dependiente de la variedad y que reducir la carga de radiación en viñedos de clima mediterráneo podría tener efectos positivos en la EUA de la vid. La efectividad de la técnica de LLR parece depender de sus efectos sobre la relación área foliar/producción y el estado hídrico de la vid, la capacidad fotosintética compensatoria de la variedad y de las condiciones ambientales. Por consiguiente, en viñedos de baja vigorosidad, una defoliación severa puede no ser aconsejable para adaptar las variedades Bobal y Tempranillo al calentamiento global debido a los efectos perjudiciales sobre la calidad del vino tinto. Por el contrario, los resultados de los experimentos de riego deficitario y de orientación de las filas de espaldera proporcionan nuevos hallazgos en la EUA como posibles técnicas para paliar la escasez de agua en el viñedo. Por lo tanto, las técnicas de campo estudiadas resultan eficaces en adaptar la viticultura mediterránea al cambio climático en cuanto al estrés hídrico. Sin embargo, sus efectos en términos de mitigación del estrés térmico no fueron del todo positivos. Por tanto, es necesario realizar más investigaciones para determinar la viabilidad de emplear otras prácticas de campo, distintas al LLR, para equilibrar la madurez glúcida y fenólica de la uva.
Field practices for adapting Mediterranean viticulture to climate change Mediterranean viticulture is being affected by climate change, which threatens wine typicity and, therefore, the whole viticulture sustainability. The main factors expected to affect grapevine cultivation are water scarcity, warm air temperature and the increase in the air carbon dioxide concentration, and impact of these factors will be mainly the: i) advancing of grapevine phenology, thereby decoupling berry technological and phenolic composition and ii) increasing vine water requirements. This PhD Thesis aimed at evaluating the effects of different field practices to adapt Mediterranean grapevine cultivation to climate change. Three experiments were performed in Valencia (Spain) to assess the effects of 1) regulated deficit irrigation; 2) training systems architecture and; 3) canopy management. The main responses evaluated were vineyard water-use efficiency (WUE) and grape composition. Experiment 1 was undertaken for three seasons in a drip-irrigated, cv. Muscat of Alexandria/161-49C vineyard to define the most sustainable irrigation strategy for white winegrapes in eastern Spain. For this, four treatments were tested: (i) Control, irrigated at 100% of estimated crop evapotranspiration (ETc) for the entire season; (ii) sustained deficit irrigation (SDI), irrigated at 50% of Control; (iii) early deficit (ED), where pre-veraison irrigation was withheld, followed by 100% ETc; and (iv) late deficit (LD), irrigated as in the Control until veraison and thereafter at 25% ETc until harvest. Results showed that yield in ED and LD was reduced 25 and 15%, respectively, compared to that of the Control, while yield under SDI did not differ significantly from that of the Control and was similar to that of the ED and LD treatments. All the deficit irrigation treatments had some carry-over effects on vine performance due to a significant decrease in shoot fruitfulness and in cluster mass due to smaller berries. Experiment 2 highlights that the response to the minimizing of the radiation load intercepted by the canopy is cultivar-dependent and that decreasing the radiation load in the Mediterranean vineyards could have positive effects on the whole vine's WUE. The effectiveness of the LLR technique seemed to depend on its final impacts on leaf area-to-fruit ratio and vine water status, the cultivar's photosynthetic compensation capacity and the environmental conditions. Therefore, under low vigour vine conditions, severe defoliation might not be advisable for adapting Bobal and Tempranillo to global warming due to the detrimental effects on red wine quality. On the contrary, the results of deficit irrigation and row orientation experiments provided novel insights on WUE as possible techniques to alleviate vineyard water scarcity. Therefore, the field practices studied are effective in adapting Mediterranean viticulture to climate change in terms of water stress. On the other hand, the impacts of the studied techniques in terms of thermal stress alleviation were not fully positive. Hence, further research is needed to determine the possibility of using other field practices, besides LLR, to couple berry sugars and phenolic maturity.
Tècniques de cultiu per adaptar la viticultura mediterrània al canvi climàtic La viticultura mediterrània s'està veient afectada pel canvi climàtic, el que amenaça la tipicitat del vi i, per tant, la sostenibilitat de la vitivinicultura. Els principals factors que es preveu que afecten el cultiu de la vinya són l'escassetat d'aigua, els increments tèrmics i l'augment de la concentració de diòxid de carboni en l'aire, el que influirà en la vinya: i) avançant la seva fenologia, dissociant així la maduració tecnològica i fenòlica del raïm i ii) incrementant les necessitats hídriques de la vinya. Aquest treball pretén avaluar els efectes de diferents tècniques de cultiu per a l'adaptació de la viticultura mediterrània al canvi climàtic. Es van realitzar tres experiments a València (Espanya) estudiant els efectes de: 1) el reg deficitari controlat; 2) l'arquitectura dels sistemes de conducció i 3) el maneig del dosser vegetal. Les principals respostes avaluades van ser l'eficiència en l'ús de l'aigua de la vinya (EUA) i la composició del raïm. L'experiment 1 es va dur a terme durant tres campanyes en una vinya de Moscatell d'Alexandria/161-49C regat per goteig amb l'objectiu de definir l'estratègia de reg més sostenible per al raïm blanc en el llevant espanyol. A tal efecte, es van assajar quatre tractaments: (i) Control, regat al 100% de l'evapotranspiració del cultiu (ETc) durant tota la campanya; (ii) reg deficitari sostingut (SDI), regat al 50% del Contol; (iii) dèficit primerenc (ED), on es va restringir el reg abans del verol, seguit d'un 100% d'ETc; i (iv) dèficit tardà (LD), regat com el Control fins al verol i posteriorment al 25% de l'ETc fins a la verema. La producció en l'ED i el LD es va reduir en un 25 i 15% respectivament en comparació a la del Control, mentre que la producció del SDI no va diferir significativament del Control ni dels tractaments d'ED i LD. Tots els tractaments amb reg deficitari mostraren efectes acumulatius en la productivitat dels ceps, com a conseqüència de la reducció del nombre de raïms per sarment i del tamany del pomell a causa de la menor grandària de la baia. L'experiment 2 posa de manifest que la resposta a la minimització de la radiació interceptada pel dosser vegetal és dependent de la varietat i que reduir la càrrega de radiació en ceps de clima mediterrani podria tindre efectes positius en l'EUA de la vinya. L'efectivitat de la tècnica de LLR pareix dependre dels seus efectes sobre la relació àrea foliar/producció i l'estat hídric de la vinya, de la capacitat fotosintètica compensatòria de la varietat i de les condicions ambientals. Per consegüent, en vinyes de baixa vigorositat, una defoliació severa pot no ser recomanable per a adaptar les varietats Boval i Ull de llebre al calfament global, tenint en compte els efectes perjudicials sobre la qualitat del vi negre. Per contra, els resultats dels experiments de reg deficitari i d'orientació de les files d'espatlera proporcionen noves troballes en l'EUA com a possibles tècniques per pal·liar l'escassetat d'aigua a la vinya. Per tant, les tècniques de camp estudiades resulten eficaces a adaptar la viticultura mediterrània al canvi climàtic pel que fa a l'estrés hídric. No obstant, els seus efectes en termes de mitigació de l'estrés tèrmic no van ser del tot positius. Per tant, cal realitzar més investigacions per a determinar la viabilitat d'emprar altres pràctiques de camp, distintes al LLR, per a equilibrar la maduresa glúcida i fenòlica del raïm.
Buesa Pueyo, I. (2018). Field practices for adapting Mediterranean viticulture to climate change [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/107365
TESIS

The goal of this study was to determine the nature and factors influencing smallholder farmers in their adoption decision-making regarding the use of soil conservation practices introduced by extension practitioners in South Africa, using the case of farming at Qamata Irrigation Scheme, Eastern Cape. Using a central argument (thesis statement), the study argued that an adequate understanding and definition of smallholder farmers’ adoption decision-making process is very crucial to solving the problem of soil erosion/ degradation problem amongst smallholder farmers. Adopting the case study research design, information from 70 crop farmers (in a farmer focus group interviews) form the basis of the study. Basic models of analysis were the multiple, probit and logit, as well as the binary logistic regression analyses. According to the empirical results, perception was found very relevant in adoption decision-making, interacting positively and significantly with eight of the seventeen adoption variables chosen for the study. The indication therefore is that age (p<0.050), education (p<0.0030), and marriage (p<0.036), have more potentials to improve farmers’ perception. Similarly, higher farmer incomes (from crops [p<0.017], off-farm [p<0.038] and overall [p<0.011] income) also have a likelihood to improve farmers’ perception regarding soil conservation, for improved adoption. Further indication is that farmers who are aware (p<0.015) of the soil practices introduced by extension are also those who participate in their use (p<0.041). Employing the binary logistic, probit and logit regression models, results suggest that the nature of adoption decision-making processes of smallholder farmers is complex (not straight), being influenced by multiple factors. While age (p<0.099), gender (p<0.031), total income (p<0.081) impacted positively significant on smallholder farmers’ adoption decision-making, marital status (p<0.025), sources of land (p<0.063), length of continuously farming on same piece of land (p<0.013), and level of crop production (p<0.002) impacted negatively. The indication therefore was that older farmers preferred their own practices to the recommended practices by extension, which is in line with literature. Also as expected, more females preferred their own practices to extension recommended, while more males preferred the recommended practices. Similarly, marriage, land ownership, farming continuously on a spot for a long period, as well as increase in the level of crop production, all had a propensity to influence farmers toward the adoption of extension recommended practices as against farmers’ practices. Further results indicate, that farmers’ education (p<0.032), household size (p<0.37), and income (off-farm [p<0.036] and total [p<0.004]), measures used to measure farmers’ livelihood standards in the study, were positively significant in association with adoption. The indication was that, adoption decision-making is potentially capable of improving education level of farmers; increase the size of household, thus providing easy family labour; and as well improve level of income for the farmer. Based on the foregoing, the suggestion therefore is that any technology intervention programme that will succeed must begin with a clear understanding and analysis of farmers’ adoption process. This is better achieved when the adoption process is seen as a four-stage process, where the farmer first forms a view about the innovation (perception stage), and then decides whether or not to use it (adoption stage), as well as how much of the innovation to adopt (level of adoption stage), and finally how much is this innovation going to affect my livelihood (impact of adoption stage). Also, due to the particular relevance of perception in the adoption decision-making process, technology disseminators (extension), researchers and policy makers alike must never conclude on the rejection of any technology, not until factors determining perception of individuals have been well studied. The notion here is that, even at the confirmation stage of the adoption process of an individual adopter, when a rejection is confirmed, for an example, analysing factors of the adopter’s perception at play at the particular time of the innovation in question, could go a long way to redirecting the course of the adoption process of the said individual.

Thesis (PhD)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: Aquaculture has proven to be a viable operation in multi-used irrigation reservoirs (also referred to as farm dams) in the Western Cape province (WCP) of South Africa. Many studies found that the fitness-for-use of these reservoirs for both net cage culture of fish and irrigation of crops is feasible. However, practising intensive fish farming in existing open water bodies can increase the nutrient levels of the water through organic loading, originating from uneaten feeds and fish metabolic wastes. Under such conditions the primary (irrigation) and secondary (drinking water and recreation) usage of the dam could be compromised by deteriorating water quality. Rainbow trout (Oncorhynchus mykiss) farming is done in Mediterranean climatic conditions of the WCP. This type of climate presents short production seasons with fluctuating water quality and quantity. The study investigated the dynamics of water physico-chemical parameters and assessed the long term impact of rainbow trout farming on irrigation reservoirs. Furthermore, associated land-use in the catchment of such integrated aqua-agriculture systems is described, and mitigation to minimise the impact of fish farming evaluated. The investigation concluded with assessing the contribution of aquaculture to rural and peri-urban communities. The aim is to present an integrated, socio-ecologically balanced farming system for irrigation reservoirs with associated aquaculture activities. A total of 35 reservoirs, including both fish farming and non-fish farming ones, were selected as research sites. They were located in three geographical regions namely, Overberg (Grabouw/Caledon), Boland (Stellenbosch/Franschhoek) and Breede River (Ceres/Worcester). Reservoirs were <20 ha in surface area and the volume ranges from 300 000 to 1 500 000 m3. Water samples were collected monthly and seasonally for the different investigations and analysed for a range of water quality parameters, including: transparency (Secchi disc), temperature, dissolved oxygen (DO), pH, sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), chloride (Cl), carbonate (CO3), bicarbonate (HCO3), manganese (Mn), copper (Cu), zinc (Zn), boron (B), total phosphorous (TP), orthophosphate (PO4), total ammonia nitrogen (TAN), nitrate-nitrogen (NO3-N), nitrite-nitrogen (NO2-N), aluminium (Al), total suspended solids (TSS), total dissolved solids (TDS), alkalinity, hardness and sulphate. Phytoplankton samples were also collected, genera identified and biomass calculated. The water quality data were analysed in terms of surface and bottom strata in both fish farming and non-fish farming reservoirs based on repeated measurements at the same site location at different times using the procedure General Linear Models of Stastical Analysis System (SAS, 2012). Values p<0.05 were considered as statistically significant. A Principal Component Analysis (PCA) biplot was used to graphically depict all the sites and measured water quality variables with the purpose of trying to see whether the fish farming and non-fish farming ones showed any groupings and how the sites were related to the measured variables. Structured questionnaires and informal discussions were used to collect additional information on the water use, production data and socio-economic effects on fish farmers. Categorical data gathered from the interviews (21 aquaculture projects) were analysed for frequency of occurrence using the Statistical Product and Service Solutions (SPSS) computer programme (SPSS Systems for Windows, Version 12.0). Results are presented in publication form with research chapters focusing on the subject areas of water quality impact, catchment land-use, potential mitigation measures and aquaculture contribution. Results for the water quality analyses indicated that as a collective, the farm reservoirs’ overall minimum, mean and maximum values for the physico-chemical parameters were fit-for-use for trout farming. The depth of the reservoirs ranged from 1.2 - 21.6 m with the low value taken during the summer season. Values lower than 5.0 m can cause management problems for floating cages that require a minimum of 4.0 m for net suspension and 1.0 m of free space below for adequate lateral flow. The Secchi disc reading of the reservoirs ranged from 10 – 510 cm. Higher transparencies were recorded after the winter rains when sand, silt and clay settled. Trout feeding is dependent on visibility and transparencies of more than 50 cm are required for good feeding conditions. The dissolved oxygen (DO) ranged from 0.3 – 16.4 mg/L with values below 5.00 mg/L recorded during summer when extraction and temperatures were high and provided conditions unable to sustain trout farming. The situation reverses with the onset of winter when the dams fill and DO rises above 5.00 mg/L as required for trout farming. The phosphorous (P) levels ranged from 0.001 – 0.735 mg/L. Higher concentrations were recorded during the winter turnover phase when bottom and surface waters mixed. Concentration above 0.01 mg/L can cause eutrophication of the water bodies. Total ammonia nitrogen (TAN) ranged from 0.015 - 6.480 mg/L. Higher concentrations were recorded during summer when temperatures were high and depths were low. TAN can be toxic to fish when the pH and temperature are high. The generally low least square means (LSM) for TAN were indicative of minor environmental impact of trout farming operations conducted during the colder, winter rainfall months. Trout farming coincided with conditions where the water temperatures were low, dam levels were high and dams were overflowing. The difference in bottom and surface water quality of reservoirs and the site location were found to be more important than the absence or presence of fish farming. The difference in bottom and surface water is directly linked to the ecological status of the sediment, which serve as nutrient sinks. In monomictic dams found in Mediterranean areas, mixing occurs during the winter turnover phase. Nutrients are released due to surface and bottom water mixing, brought about by torrential rains and wind turbulence. The concentration of organic material in the sediment and bottom waters is a function of the nutrient loading over time, irrespective whether the non-point sources were fish farming or agricultural activities and therefore it is difficult to partition causes and effects. In cases where reservoirs were already eutrophic due to past agricultural practices, implementing aquaculture could exacerbate the poor water quality status of the reservoir. There was a statistically significant difference between fish farming and non-fish farming for phosphorous, Secchi disc, total suspended solids and nitrite-nitrogen (p<0.05) and no statistically significant difference between fish farming and non-fish farming for dissolved oxygen, total ammonia nitrogen and nitrate-nitrogen (p>0.05). There was a statistically significant difference between surface and bottom waters for P and TAN (p<0.05). One reason for higher P and TAN concentrations in bottom waters is the accumulation of both in the sediment and subsequent release in the water column when the water mixes. A two-dimensional scatter plot was generated using the score for the first two principal components. The first two principal components accounts for 40 and 17 % of the total variance respectively, and the two groups of fish farming and non-fish farming did not separate well based on the first two principal components. The occurrence and distribution of phytoplankton biomass fluctuated with dam water levels and nutrient concentrations. The prevailing phytoplankton communities are important to fish farmers for two reasons: 1. It leads to fluctuations in dissolved oxygen concentrations via users (respiration and decomposition) and producers (photosynthesis). 2. It could lead to algal taint of fish flesh when geosmin-producing phytoplankton species are present. The frequency of occurrence indicated that the Group Chlorophyta (including genera, Chlamydomonas, Closterium, Oocystis, Scenedesmus, Staurastrum, Tetraedron, etc) had the most occurrences (n=371) with Chrysophyta (including genera, Dinobryon, Mallomonas, Synura, etc) the least (n=34). There was a statistically significant difference between genera occurrence and season (p<0.05). The geographical location of sites had no significance influence on the frequency of phytoplankton occurrence. There was no direct link between water quality and production yield (p>0.05). The fish yield of farms were linked mainly to the quality of fingerlings and the feed conversion ratio (FCR) achieved (p<0.05). Land-use patterns in the catchment where fish farming dams were located have shown that the dams are multiple-used systems. The ecological integrity of the farm dam ecosystem is dependent on the base volume. The dam is primarily for irrigation and fish farming can be compromised when higher demand for water is required during the dry season. The dams receive about 20 % of its water from rainfall and the rest from runoffs. Farmers could not provide accurate extraction rates making it difficult to predict water levels for future fish production. Four potential mitigation measures to reduce nutrient loading were described namely, feed management (quantity, frequency, type, etc.), feeding method (demand feeders, hand feeding), feed ingredients (formulation) and floating gardens. Both feed management procedures and demand feeders were evaluated as to the efficiency of reducing feed wastage and optimising FCR’s. The small-scale fish farmers were producing approximately 6 tons and had an average FCR of 1.96:1 ± 1.15. If farmers could improve their FCR’s by 0.1 (i.e. from 1.96 to 1.86), it would translate into a reduction of 100 kg feed for every ton of fish produced and result in 5% decrease in nutrient loading. The results of the water analysis and visual assessment of faecal length and colour showed no statistically significant difference between treatments for the guar-gum based binder (p>0.05). In addition, the level of binder did not influence digestibility of the experimental diets. The floating garden study indicated that it was feasible to construct a low cost raft system that is easy to manage and can produce plant crops as a hydroponic system in conjunction with fish farming cages. The lettuces grown on farm dam water provided support for the premise that the water quality can be improved via extraction of nutrients for crop production. For the production of 3.5 kg/m2 lettuce, a ratio of 1.09 plants/fish equal to 1.84 g feed/day/plant would reduce the accumulation of soluble nutrients around floating net cage farming system. The socio-economic evaluation of the contribution of fish farming to the welfare of rural and peri-urban farming communities supported the notion that aquaculture can lead to the upliftment of participating communities. Seventy-one percent (71%) of the respondents indicated that their motivation for exploring aquaculture is to supply fish to the wholesale market in order to generate income. Sixty-one percent (61%) of the respondents conducted the sales themselves or co-opted family members to assist them. The contribution of aquaculture provided direct benefits through improvement in household income, subsistence food supply and skills development. Indirect benefits included providing an information hub for other emerging farmers, elevation of the fish farmer’s status in the community through greater wealth and knowledge creation and promoting sector diversification through new products and technology. The three main constraints to the promotion and growth of aquaculture were listed as lack of government support, insufficient market intelligence and access, and limited choice in the availability of suitable candidate aquaculture species. Irrigation reservoirs in the WCP have a history of enrichment through external sources supplying water via agricultural runoff (fertilisers and pesticides), catchment runoff (leaf litter and organic debris) and stormwater effluent (grey and black water). The incorporation of aquaculture into such dams adds extra nutrients to the water column and management is crucial to limit the nutrient loading and ensure environmental sustainability. Such an approach will ensure that commercial land-based crop farmers’ irrigation regime and water distribution operations would not be negatively affected. Therefore future research needs should focus on; firstly the prevention and minimisation of pollution deriving from aquaculture through improved production management and technology transfer, secondly the monitoring and evaluation of the catchment ecosystem as a continuum with all the external factors affecting the ecology of farm dams and thirdly, evaluating the sediment processes and dynamics as sinks for nutrient accumulation.
AFRIKAANSE OPSOMMING: Akwakultuur het getoon dat dit ‘n lewensvatbare inisiatief is vir meerdoelige-gebruik van besproeiingsdamme (ook genoem plaasdamme) in die Wes-Kaap provinsie (WKP) van Suid-Afrika. Vele studies het bewys dat die geskiktheid-vir-gebruik van die reservoirs haalbaar is vir beide visproduksie sowel as besproeiing van landbougewasse. Nieteenstaande, die beoefening van intensiewe visboerdery in bestaande buitelug watersisteme kan lei tot ‘n toename in nutriëntvlakke van die water as gevolg van organiese belading afkomstig van ongevrete voere en metaboliese afvalstowwe van die vis. Onder sulke omstandigthede kan die primêre- (besproeiing) en die sekondêre (drinkwater en rekreasie) gebruik van die dam in gedrang kom weens ‘n afname in waterkwaliteit. Reënboogforel (Oncorhynchus mykiss) boerdery word beoefen in die omliggende Mediterreense klimaat van die WKP. Die tipe klimaat verskaf kort produksie-seisoene met wisselvallige water kwaliteit en kwantiteit. Die studie het die dinamika van water se fisies-chemiese parameters ondersoek en het die impak van forelboerdery op besproeiingdamme oor die langtermyn beskryf. Verder het die studie die geassosieerde landgebruik in die opvangsgebied met geïntegreerde akwa-landbou sisteme beskryf, asook moontlike toetrede (mitigasie maatreëls) geëvalueer wat die impak moontlik kan verlaag. Die ondersoek is afgesluit deur die bydrae wat akwakultuur lewer aan landelike en semi-stedelike gebiede, te beskryf. Die hoofdoel is die daarstelling van ‘n geïntegreerde, sosio-ekologiese gebalanseerde sisteem vir besproeiingdamme met gesamentlike akwakultuuraktiwiteite. ‘n Totaal van 35 besproeiingsdamme, insluitend die met visboerdery en nie-visboerdery, is gekies as navorsingspersele. Dit is hoofsaaklik geleë in drie geografiese gebiede naamlik, Overberg (Grabouw/Caledon), Boland (Stellenbosch/Franschhoek) en Breederivier (Ceres/Worcester). Die reservoirs is almal < 20 ha in oppervlakarea en die volumes het gewissel van 300 000 – 1 500 000 m3. Watermonsters is maandeliks sowel as seisoenaal versamel vir die onderskeie ondersoeke en ontleed vir ‘n reeks van parameters, insluitend: sigbaarheid (Secchi disc), temperatuur, opgeloste suurstof (OS), pH, natrium (Na), kalium (K), kalsium (Ca), magnesium (Mg), yster (Fe), chloor (Cl), karbonaat (CO3), bikarbonaat (HCO3), mangaan (Mn), koper (Cu), sink (Zn), boor (B), totale fosfor (TP), ortofosfaat (PO4), totale ammoniak stikstof (TAN), nitraat-stikstof (NO3-N), nitriet-stikstof (NO2-N), aluminium (Al), totale gesuspendeerde vaste stowwe (TGV), totale opgeloste vaste stowwe (TOV), alkaliniteit, hardheid en sulfate. Phytoplanktonmonsters is ook versamel, genera geïdentifiseer en die biomassa bepaal. Die waterkwaliteitsdata is ontleed in terme van oppervlak- en bodemstrata vir beide visboerdery en nie-visboerdery reservoirs en was gebaseer op herhaalde metings by dieselfde perseel op verskillende tye deur gebruik te maak van die Algemene Liniêre Model van Statistiese Analitiese Sisteem (SAS, 2012). Waardes p<0.05 is oorweeg as statisties beduidend. ‘n Hoofkomponentanalise bi-stipping (HKA) is toegepas om die persele en veranderlikes grafies voor te stel en te bepaal of die visboerdery en nie-visboerdery s’n enige groeperinge vorm asook hoe die persele assosieer met die veranderlikes. Gestruktureerde vraelyste en informele besprekings is onderneem om inligting in te samel op watergebruik, produksie-data, en die sosio-ekonomiese invloed wat akwakultuur bied aan visboere. Kategoriese data wat deur die onderhoude (21 akwakultuurprojekte) ingesamel is, is ontleed vir die frekwensie van aanwesigheid deur die gebruik van Statistiese Produk en Dienste-oplossings (SPDO) rekenaarprogram (SPSS Systems for Windows, Version 12.0). Die resultate vir die verskeie ondersoeke is beskryf en saamgestel in publikasie-vorm met die navorsingshoofstukke wat gefokus het op die areas van waterkwaliteitsimpak, opvangsgebied landgebruik, toetrede-meganismes en die bydrae van akwakultuur. Die resultate vir die waterkwaliteitsanalises het getoon dat gesamentlik die reservoirs se oorhoofse minimum, gemiddelde en maksimum waardes vir die verskillende fisies-chemiese parameters geskik is vir forelboerdery. Die diepte van die reservoirs het gewissel van 1.2 - 21.6 m, met die laagste waarde aangeteken gedurende die somermaande. Waardes laer as 5.0 m kan bestuursprobleme vir drywende hokstelsels versoorsaak want ‘n minimum van tenminste 4.0 m vrye spasie onder die hokke word benodig vir voldoende laterale vloei. Die Secchi-skyf lesing (sigbaarheid) van die reservoirs het gewissel van 10 – 510 cm. Hoër sigbaarheidswaardes is aangeteken na winterreëns wanneer sand-, slik- en klei deeltjies uitgesak het. Forel voer op sig en sigbaarheid van > 50 cm word benodig om goeie voeding te handhaaf. Die OS het gewissel van 0.3 – 16.4 mg/L met waardes onder 5 mg/L aangeteken gedurende somer wanneer wateronttrekking en temperature hoog was. Dit het gelei tot ongunstige toestande vir forelboerdery. Die situasie swaai om met die begin van winter wanneer die damme vol reën en die OS bo 5 mg/L styg soos benodig vir forelboerdery. Die P-vlakke het gewissel van 0.001 – 0.735 mg/L. Hoër waardes is aangeteken gedurende die winteromkeerfase wanneer die bodem en oppervlak se water meng. Konsentrasies bo 0.01 mg/L kan tot eutrofikasie van watersisteme lei. TAS het gewissel van 0-015 – 6.480 mg/L. Hoër konsentrasies is aangeteken gedurende die somer wanneer temperature hoog is en damvlakke laag. By hoë pH’s en temperature kan TAS toksies wees vir vis. The algemene lae kleinste kwadaat gemiddelde (KKG) waarde vir TAS het getoon dat daar ‘n klein impak op die omgewing was wanneer forelboerdery bedryf word gedurende die koue, winter reënvalmaande. Forelboerdery val saam met omstandigthede wanneer die watertemperature laag is, damvlakke hoog en die reservoirs oorloop. Die verskil in die bodem- en oppervlak water in die besproeiingsdamme en die ligging van die perseel is vasgestel om meer belangrik te wees as die teenwoordigheid of afwesigheid van visboerdery. Die verskil in die bodem en oppervlak is toe te skryf aan die toestand van die sediment waar nutriënte kan opgaar. In monomiktiese damme soos gevind in Mediterreende areas, vind vermenging plaas gedurende die winteromkeerfase. Nutriënte word vrygestel a.g.v. die vermenging van die oppervlak en bodem se water wat dan veroorsaak word deur harde reën en windturbulensie. Die konsentrasie van organiese materiaal in die sediment en bodem water is ‘n funksie van die nutriëntlading met tyd, ongeag of dit afkomstig was vanaf visboerdery of landbou-aktiwiteite. Dit is dus moelik om die spesifieke oorsaak van besoedeling af te baken. In gevalle waar die reservoirs alreeds eutrofies is a.g.v. aangewese landbouaktiwiteite, kan die toestand van die waterbron vererger indien akwakultuur toegepas word. Daar is ‘n statistiese noemenswaardige verskil tussen visboerdery en nie-visboerdery vir P, Secchi-skyf, totale gesuspendeerde vaste stowwe en nitrite-stikstof (p<0.05), en geen statistiese noemenswaardige verskil tussen visboerdery en nie-visboerdery vir OS, TAS en nitraat-stikstof (p>0.05). Daar is ‘n statistiese noemenswaardige verskil tussen oppervlak- en bodem water vir P en TAS (p<0.05). Een moontlike rede vir hoër P en TAS konsentrasies in die bodemwater, is die akkumulasie van beide parameters in die sediment en gevolglike vrystelling in die waterkolom wanneer die water gemeng word. ‘n Twee dimensionele spreidingstipping is geprodueer deur die waardes te gebruik van die eerste twee hoofkomponente. Die eerste twee hoofkomponente dra by 40 % en 17 % van die totale variansie onderskeidelik, en die twee groepering van visboerdery en nie-visboerdery het nie duidelik getoon nie. Die voorkoms en verspreiding van phytoplankton biomassa het gewissel met die verandering in damvlakke en nutriëntkonsentrasies. Die aanwesige phytoplanktongemeenskappe is belangrik vir die visboer vir twee redes: 1. Dit kan wisselende OS-vlakke versoorsaak deur die verbruik (respirasie en dekomposisie) en produksie (fotosintese) daarvan. 2. Dit kan lei tot alge na-smake van vis wanneer geosmin-produserende phytoplankton spesies aanwesig is. The frekwensie van voorkoms het getoon dat die Groep Chlorophyta (insluitend die genera, Chlamydomonas, Closterium, Oocystis, Scenedesmus, Staurastrum, Tetraedron, ens.) die meeste voorkom (n=371), met Chrysophyta (insluitend die genera, Dinobryon, Mallomonas, Synura, ens.) die minste (n=34). Daar is ‘n statistiese noemenswaardige verskil tussen genera voorkoms en seisoen (p<0.05) vir phytoplankton. Die geografiese ligging van die perseel het geen noemenswaardige invloed op die frekwensie van phytoplankton voorkoms nie. Daar is geen statistiese noemenswaardige verbintenis tussen waterkwaliteit en visproduksieopbrengste nie (p>0.05). Die visopbrengste by plase is hofsaaklik afhangende van die kwaliteit van die vingerlinge en die voeromsettingsverhouding (VOV) wat bereik is (p<0.05). Die landgebruikspatrone in die opvangsgebied waar visboere gesetel is, het aangedui dat die besproeiingsdamme meeldoelige sisteme is. Die ekologiese integriteit van die plaasdam-ekosisteem is afhanklik van die basisvolume. Die dam is hoofsaaklik daar vir die besproeiing en visboerdery kan in gedrang kom wanneer daar ‘n hoër aanvraag vir water gedurende die droë seisoen is. Die damme het omtrent 20 % van die water vanaf reënval ontvang en die res van aflope. Boere kon nie akkurate inligting verskaf van waterontrekking nie wat dit moeilik gemaak het om te voorspel wat die beskikbare watervlakke in die toekoms sou wees vir visproduksie. Vier potensiële toetrede meganismes om die nutriëntlading te verminder, is beskryf naamlik voedingsbestuur, (kwantiteit, frekwensie, tipe, ens.) voermetodes (aanvraagvoeder, handvoeding), voerbestandele (formulasies) en drywende tuine. Beide voedingsbestuur prosedure en aanvraagvoeders is geëvalueer as ‘n metode om die voervermorsing te verminder en die VOV te verbeter. Die kleinskaalse visboere het ongeveer 6 ton produseer met ‘n gemiddelde VOV van 1.96:1 ± 1.15. Indien die visboere hul VOV’s met 0.1 kan verbeter (bv. van 1.96 tot 1.86), sal dit beteken dat daar ‘n vermindering van 100 kg voer bewerkstellig word vir elke ton vis geproduseer. Dit kan ook lei tot ‘n vermindering van 5 % in die nutriëntlading. Die resultate van die wateranalises en die visuele waarneming van faeceslengte en kleur het geen statistiese noemenswaardige verskil tussen die behandelinge vir die guar-gom binder getoon nie (p>0.05). Verder, die hoeveelheid van die binder het nie die vertering van die eksperimentele diëte beïnvloed nie. Die studie op die drywende tuine het getoon dat dit haalbaar is om ‘n lae-koste sisteem te bou wat maklik is om te bestuur en gewasse kan produseer soos in ‘n hidroponiese sisteem tesame met visproduserende hokstelsels. Die kropslaaie se groei het getoon dat die waterkwaliteit van besproeiingsdamme kan verbeter word deur die opname van nutriënte wanneer plante verbou word. Vir die produksie van 3.5 kg/m2 kropslaaie, sal ‘n verhouding van 1.09 plante/vis of 1.84 g voer/dag/plant die akkumulasie van opgeloste nutriënte rondom die hokstelsels verminder. Die sosio-ekonomiese evaluasie van die bydrae van visboerdery tot die welvaart van die landelike en semistedelike plaasgemeenskappe ondersteun die feit dat akwakultuur verbetering kan bewerkstellig, veral onder deelnemende gemeenskappe. Een-en sewentig persent (71 %) van die respondente het getoon dat hul oorweging vir die bedryf van akwakultuur is om vis te voorsien aan die grootmark en daarvolgens geld te maak. Een-en-sestig persent (61 %) van die respondente het aangedui dat hulself die vis verkoop of vir familie-lede vra om met die verkope te help. Die bydrae van akwakultuur het direkte voordele aan die deelmers voorsien deur ‘n verbetering in huishoudelike inkomste, voedselvoorsiening vir selfgebruik en die ontwikkeling van vaardigthede. Indirekte voordele sluit in dat die deelmers ‘n bron van inligting geword het vir opkomende boere, hul status in die gemeenskap het verbeter omdat hul kennis verbreed het en dit het verder gelei tot diversifisering in die sektor a.g.v. die skepping van nuwe produkte en tegnologie. Die drie hoof struikelblokke wat die groei en bevordering van akwakultuur belemmer is o.a., ‘n tekort aan staatsondersteuning, onvoldoende markinligting en toegang en ‘n beperkte keuse in spesies vir boerdery. Besproeiingsdamme in die WKP het ‘n geskiedenis van verryking deur eksterne bronne wat water voorsien vanaf landbou-afloop (bemestingstowwe en pesbestrydingsmiddels), opvangsgebied-afloop (blare en ander organiese debris) en stormwateruitlaat (gruis- en swart water). Die implementering van akwakultuur in sulke damme voeg addisionele nutriënte tot die waterkolom en bestuur is krities om die lading te verminder en te verseker dat omgewingsvolhoubaarheid behou word. Indien die regte praktyke en bestuur toegepas word, sal dit beteken dat die kommersiële boer se besproeiing en waterverspreiding nie negatief beïnvloed word nie. Vervolgens moet toekomstige navosingsbehoeftes fokus op eerstens, die voorkoming en vemindering van besoedeling afkomstig van akwakultuur deur verbeterde produksie-bestuur en tegnologie-oordrag, tweedens, die monitoring en evaluering van die opvangs-ekosisteem as ‘n kontinuum met al die eksterne faktore wat die ekologie van die plaasdam kan beïnvloed en laastens, die ondersoek en evaluering van die sediment se prosesse en dinamika as ‘n sisteem wat nutriënte ophoop.

The South African sheep industry has experienced an increase in the price of meat and wool over the past several years. This has led to an interest in intensification of sheep production off planted pastures. Due to this phenomenon an economic viability study was done on the intensification of sheep production on cultivated pastures under irrigation. When intensifying sheep production, certain management practices need to be incorporated in order to enhance the output obtained per hectare and to overcome the higher input cost of production. Management practices that could be included are creep feeding, accelerated breeding and feedlotting of lambs after weaning. In order to determine the economic viability of such a system, certain production parameters need to be obtained for producing sheep intensively from cultivated pastures. Three studies were conducted to obtain the required production parameters; these were then followed by an economic evaluation incorporating the parameters obtained from the studies. All the studies were conducted at Kromme Rhee and Langgewens, two research farms of the Department of Agriculture in the Western Cape.

In India, the 1992 Reservation Law and the 2006 Mahatma Gandhi National Rural Employment Guarantee Act (MGNREGA) have formalised women as legitimate actors in rural development. These gender-inclusive policies do not necessarily conform to the traditional domestic role of women, which often precludes them from formally engaging in political processes and labour outside the home. In Northern India, these major policy shifts are illustrated in ancient irrigation management systems. With growing rural outmigration and climatic variability aggravating water resources and food security issues, irrigation management is increasingly dependent on the active participation of women. Yet irrigation management is still widely perceived as a male responsibility. This thesis investigates how women adapt and respond to new institutionally mandated responsibilities and expectations as female leaders and as water users. The research is presented in four complementary papers based on quantitative and qualitative data collected during fieldwork in Delhi and Himachal Pradesh. Three major findings emerged to contribute to theories and evidence of the role of public policies in shaping gendered outcomes for common pool resource management in irrigation system in India. First, gender norms affect women differently depending on their public role in the community. Unlike non-political women, female leaders, as public figures, must secure communal approbation to gain power, credibility, and socio-economic networks. As a result, female leaders shape their political behaviour and policy preferences around local notions of femininity, female morality, and labour-based ideas of expertise. Second, for female water users, gender inclusive policies that legitimise their role as participants in formal political processes and the labour force for irrigation management increase their likelihood to defy gender-based restrictions and engage in formal political processes around irrigation management. Third, providing that formal/legal structures legitimize their actions, women will readily breach gender norms if they are to economically benefit from it. The implication of this research are that policies aimed at providing legal support for women to engage in formal rural development, combined with formalised economic opportunities for women are effective eroding agents of gendered institutions and are catalysts in facilitating the engagement of women in all areas of rural development. Given worldwide concerns over rural development, this study encourages such governmental actions to enable the effective and full engagement of future generations of women in the formal management of common pool resources.

Brazilian commodities, such as ethanol, are looking for sustainable production to suit the international market demands. An important parameter for assessing sustainability is the carbon (C) footprint calculation of the product. Thus, studies of the variations in soil C stocks on the ethanol production are essential. Studies in relation to land use change are already been developed; however information about parameters of management changes on the sugarcane production is needed. The aim of this research was to evaluate the soil C stock in response to two main management changes in sugarcane production: i) no vinasse to vinasse application (NV-V), ii) burned to unburned harvesting system (B-UB). We also evaluated soil C stock changes in a chronosequence irrigation practices (native vegetation (NV), sugarcane irrigated 4 years (I4) and 6 years (I6), a new management in semi-arid and drought regions in Brazil which also aims high yields. Modelling approaches in order to assess long-term effects were also analysed. The NV-V transition showed higher soil C stock for V regime for topsoil layers 0-40 cm depth mainly due to the addition of organic compounds to the soil. Vinasse can also enhance biomass production and crop yield. The B-UB transition showed higher soil C stock in the UB regime from 20 to 60 cm depth due to higher organic matter accumulation from the maintenance of the straw to the field. The cumulative soil C stock for 1 metre depth had an increase of 1.1 and 0.75 Mg C ha-1 y-1 in the NV-V and B-UB transitions, respectively. From modelling was observed that V and UB sites had an increase of soil C stock by 2150, being a difference of 2.8 and 23 Mg ha-1 in the equilibrium state between NV-V and B-UB regimes, respectively. In the irrigation practices, the I4 showed higher soil C stock than NV in the 20 to 40 cm; while I6 was lower than NV in the 50 to 100 cm depth. Simulated long-term analyses showed increase of topsoil C stock of 12 and 13 Mg ha-1 for I6 and I4 area, respectively, compared to NV on 2100. The results in this study are pioneers in relation to soil C stock studies in the management transitions and irrigation practices. This information may be used as a basis for public policies decision which dealing of the land use and global warming
Commodities brasileiras, como o etanol, estão à procura de uma produção sustentável para atender às exigências do mercado internacional. Um parâmetro importante para avaliar a sustentabilidade é o cálculo da pegada de carbono (C) do produto. Assim, os estudos sobre as variações nos estoques de carbono do solo (ECS) sobre a produção de etanol são essenciais. Estudos em relação à mudança no uso da terra já estão sendo desenvolvidos; no entanto informações sobre parâmetros de mudanças de manejo na produção de cana de açúcar são necessárias. O objetivo desta pesquisa foi avaliar o ECS em resposta a duas principais mudanças de manejo: i) não vinhaça para aplicação de vinhaça (NV-V), ii) sistema queimado para não queimado (B-UB). Mudanças de ECS também foram avaliadas em sistemas de irrigação em cronoseqüência: vegetação nativa (NV), cana de açúcar irrigada por 4 anos (I4) e por 6 anos (I6). Modelagem matemática para avaliar o efeito a longo prazo também foi analisada. A transição NV-V apresentou maior ECS para o regime V em 40 cm de profundidade, devido principalmente à adição de compostos orgânicos ao solo. A vinhaça também pode aumentar a produção de biomassa e rendimento da cultura. A transição B-UB apresentou maior ECS no regime UB em 20-60 cm de profundidade devido ao acúmulo de matéria orgânica a partir da manutenção da palha no campo. O ECS acumulado para 1 metro de profundidade obteve um aumento de 1,1 e 0,75 Mg C ha-1 y-1 nas transições NV-V e B-UB, respectivamente. A partir de modelagem foi observado que os regimes V e UB obteve um aumento de ECS em 2150, sendo uma diferença de 2,8 e 23 Mg ha-1 no estado de equilíbrio para os regimes NV-V e B-UB, respectivamente. Nas práticas de irrigação, o I4 foi superior ao NV nos 20 a 40 cm; enquanto que I6 foi inferior a NV na profundidade de 50 a 100 cm. As análises de simulação a longo prazo mostraram um aumento de ECS de 12 e 13 Mg ha-1 para as áreas I6 e I4, respectivamente, em comparação com NV em 2100. Os resultados deste estudo são pioneiros em relação aos estudos de ECS nas mudanças de manejo e práticas de irrigação. Esta informação pode ser usada como base para a decisão de políticas públicas que lidam com o uso da terra e do aquecimento global

En contexte de changement global, les questions d’adaptation et de pérennisation des systèmes de production sont un enjeu agricole majeur. En Argentine, le 5ème producteur mondial de vins, les conditions thermiques et hydriques sont déjà proches des limites de la culture de la vigne. En tant que culture pérenne, son adaptation à court et moyen termes doit être pensée, dès à présent. La pérennisation de cette culture passe par une adaptation des pratiques culturales. L’objectif de cette thèse visait à proposer des outils de détection et de gestion des pratiques culturales des vignobles à partir d’imagessatellitaires optiques et radar. Une analyse préalable des évolutions du climat et de sa variabilité intrarégionale a mis en évidence les principales menaces et opportunités au regard du changement climatique. A l’échelle locale, le travail sur un grand nombre de parcelles aux caractéristiques hétérogènes a approfondi les connaissances sur l’interaction signal cible en fonction des pratiques culturales. Des cartographies de l’orientation des rangées de vignes, des surfaces protégées par des filets anti-grêles et des modes d’irrigation ont été réalisées afin de dresser un état des lieux du système viticole actuel. Ensuite, l’évaluation du potentiel des données satellitaires pour le suivi de la croissance de la vigne et de ses besoins en eau ont apporté des résultats prometteurs pour le développement d’outils d’aide à la décision pour les viticulteurs
In the climate change context, the adaptation and sustainability of agricultural systems is a major challenge. In Argentina, the 5th worldwide wine producing country, the thermal and hydrical conditions are already extreme for grapevine production. This perennial crop sustainability depends on the adaptation of cultural practices. The objective of the thesis was to develop tools for helping in cultural pratices management using optical and SAR remote sensing images. First, an analysis of climate evolution and its inner regional variability hilighted the main threats and opportunities in the climate change context. At the local scale, working on a high number of heterogeneous vineyards improved the knowledge about signal and target interaction depending on cultural practices. Maps of row orientation, areas protected by anti-hail nets and irrigation systems were produced for an inventory of the actual viticultural system conditions. Then, the potential of remote sensing data for grapevine growth monitoring and irrigation requirements was evaluated and led to promising preliminary results for developping irrigation monitoring tools destinated to grapevine producers

Potatoes (Solanum tuberosum) were grown in a fine sandy loam soil in southern Manitoba in a three-year field study comparing four water management treatments: No Drainage with No Irrigation (NDNI), No Drainage with Overhead Irrigation (NDIR), Free Drainage with Overhead Irrigation (FDIR), and Controlled Drainage with Subirrigation (CDSI). The objectives of the study were (i) to evaluate the effect of the four treatments on yield and quality of potatoes, (ii) to evaluate the effect of water management on the environment, (iii) to estimate the shallow groundwater contribution to potato water requirement, and (iv) to simulate the shallow groundwater hydrology using the DRAINMOD and HYDRUS 1-D model. Subsurface drains were installed at 0.9 m depth and at spacings of 15 m (FDIR) and 8 m (CDSI). Subirrigation was done by pumping water back into the tiles through the drainage control structures. Overhead irrigation was carried out using a travelling gun. Water table depth, soil water content, drainage outflow, nutrient concentration in drainage water, irrigation rate, weather variables, potato yield and quality parameters, and biomass were measured. Compared to the NDNI treatment, the potato yield increase in the other treatments ranged between 15-32% in 2011 and 2-14% in 2012. In 2011, potato yield from FDIR was higher than CDSI (p = 0.011) and NDNI (p = 0.001), and yield from NDIR was higher than NDNI (p = 0.034). In 2012, potato yield was higher in FDIR in comparison to NDNI (p = 0.021). In 2012, the NDIR gave higher dark ends (p = 0.008) compared to other treatments. Under dry conditions, up to 92% of the potato crop water demand could be met by shallow groundwater contribution. Compared to free drainage, controlled drainage was able to lower the nitrate export by 98% (p = 0.033) in 2010 and by 67% (p = 0.076) in 2011, and the phosphate export decreased by 94% (p = 0.0117) in 2010. A major part of the drainage flow and nutrient export took place between April and June in southern Manitoba. DRAINMOD was able to accurately predict the shallow groundwater hydrology for this particular research site.

This study is an investigation into water management policies in South Africa, their effect on water users and the perceptions users have of these policies. The investigation begins with an exposition of concepts such as water demand management (WDM), as well as integrated water resource management (IWRM). A sub-discourse of the main theme is the societal tendency to neglect its common property. Garret Hardin's groundbreaking observations on the "tragedy of the commons" (1968) are explored in an effort to locate issues of relevance in effective water management strategies. In contemplating the commons, it is evident that aspects of morality and ethics are involved. The morality of a society be it in a global or national context, seems to manifest itself in legislation and policies, and in the way these are implemented. The relevance of good governance, hydropolitics and sustainable development is also discussed to provide the necessary theoretical background to an understanding of the relationship between consumers and the water commons. Access to safe drinking water is protected in the Constitution of the Republic of South Africa Act, 108 of 1996. Flowing from the government's obligation to take reasonable legislative and other measures to achieve the progressive realisation of fundamental human rights stipulated in section 27(2) of the Constitution, the challenge since 1994 has been to provide access to water for all inhabitants and to manage the available water resources effectively. Furthermore, the objective of subsequent water legislation such as the National Water Act, 36 of 1998 and regulatory plans, like the National Water Resource Strategy has been to incorporate international trends in water governance. The Department of Water and Environmental Affairs (DWEA) divided South Africa into 19 regions, called water management areas (WMA). In this study, attention is focused on what constitutes a catchment and how a catchment management agency (CMA) governs its water resources. A description is provided of the functions of water user associations (WUAs) and how ththe Lower Orange Catchment Management Area is, for example, the blueprint from which stakeholders develop their goals. In this study, the water situation in the Lower Orange Water Management Area is under scrutiny. The focus is on the three main institutional components of water management (the Lower Orange catchment management, the Upington Islands Water User Association [UIWUA] and the //Khara Hais Local Municipality). The progress of the establishment of the Lower Orange Catchment Management Agency is outlined over a period of five years. Meanwhile, the Upington Islands Water User Association was developed and this has grown in stature. The work being done by these institutions is investigated by looking at grassroots effects, especially in respect of irrigation activities. The unique water management circumstances of the //Khara Hais Local Municipality are then investigated along with the plans outlined in their Integrated Development Plan {lOP) and their Water Services Development Plane Internal Strategic Perspective (ISP) of(WSDP). Because local irrigation operations consume most of the available surface water in the Lower Orange Water Management Area, irrigation farmers and their activities warrant closer attention. A historical overview is given of the development of irrigation in the region followed by an assessment of the role of two of the most prominent historical figures in Upington, Reverend Adriaan Schroder and Abraham "Holbors" September. Ultimately, however, the focus falls on the current state of irrigation in the area. It is possible to distinguish between the approach of large commercial farming operations and that of smaller irrigation farming units to irrigation. Specific attention is given to the perceptions of irrigation farmers as far as the policies and legislation pertaining to water issues is concerned. This study will hopefully provide the Department of Water and Environmental Affairs(DWEA), //Khara Hais Local Municipality and organised agriculture with some recommendations on efficient integrated water management strategies. It might well be of value to other municipalities who are experiencing similar problems. The aim has been to identify typical problems and potential disputes between water management institutions and relevant role-players.
Thesis (Ph.D. (Public Management and Administration))--North-West University, Vaal Triangle Campus, 2010.

Les gastroentérites aiguës affectent chaque année entre un quart et la moitié des personnes dans le Monde. Elles sont causes de morbidité, de mortalité et de coûts de santé importants. Leur transmission directe ou indirecte via l’eau, les aliments, l’air ou les surfaces inertes dépend de leur étiologie (virale, bactérienne ou parasitaire) et du contexte local. Bogotá et sa région présentent plusieurs spécificités : des eaux usées rejetées en rivière souvent sans ou après seulement un traitement primaire, la mise en décharge des papiers toilettes, couches et protections souillés par les excréments, et une consommation de fruits et légumes faible et limitée à des produits bon marché irrigués par des eaux pouvant être contaminées fécalement. Notre thèse visait à évaluer les flux de certains pathogènes entériques de l’Homme dans l’environnement à proximité de Bogotá et à essayer de relier ces flux à la santé de la population.La thèse a associé trois contributions. Premièrement, une méthode de culture du norovirus humain a été mise au point en utilisant des villosités intestinales isolées de souris comme modèle cellulaire présentant toute la diversité des cellules épithéliales intestinales. Plusieurs concentrations en trypsine ont été testées pour activer les norovirus ; la méthode a été appliquée à des échantillons fécaux et environnementaux. Deuxièmement, les contaminations en E. coli et en pathogènes entériques de l’Homme ont été suivies dans des eaux (lixiviat de décharge, eau de ruissellement, rivière, eau d’irrigation, eau potable), des légumes-feuilles mangés crus (blettes) et l'air (au-dessus d’une décharge, en zone rurale, en zone urbaine) dans la région de Bogotá. Troisièmement, l’impact des contextes socioéconomiques et des pratiques individuelles (alimentation, hygiène et santé) sur les cas de gastroentérites aiguës a été testé à partir d’enquêtes réalisées dans un district de Bogotá et analysées par divers outils (analyse en composante principale, modélisation …).Nous avons montré que les villosités intestinales isolées de souris permettent l'infection et la réplication du norovirus humain. Le virus doit être activé avec de la trypsine et a un cycle réplicatif moyen de 10 h. Les villosités sont efficaces pour obtenir un matériel biologique abondant et sont idéales pour étudier l'activité biologique du norovirus ou générer des anticorps. Elles ont permis de voir des norovirus non détectés par méthode moléculaire dans certains excréments ou échantillons environnementaux ; les échantillons positifs par méthode moléculaire ou en immunodot-blot contenaient quasiment tous des norovirus infectieux. Au niveau régional, les rejets d'eaux usées dans les rivières Bogotá et Balsillas et dans le marais Tres Esquinas contaminent le réseau d'irrigation de La Ramada au nord-ouest de Bogotá en E. coli et potentiellement en pathogènes entériques de l’Homme. Les blettes récoltées dans cette zone étaient fortement contaminées, en contraste d’autres zones de culture. Leur contamination évoluait de leur production à leur achat dans les commerces de proximité, les lavages pouvant être contaminants ou décontaminants, les manipulations sur l’étal des marchands étant contaminantes. L’air était souvent contaminé par E. coli et par Shigella spp., sans pouvoir attribuer à la décharge Doña Juana un rôle particulier. La présence de Shigella spp. était observée parallèlement dans plus de la moitié des selles des personnes diarrhéiques. Les enquêtes réalisées ont montré que la fréquence annuelle des gastroentérites aiguës diminuait avec l’accroissement de l’âge des personnes ; elle semblait plus faible dans les foyers avec personnes âgées, peut-être en lien avec des pratiques plus strictes en matière d’hygiène, alimentaire notamment
Acute gastroenteritis affect between a quarter and a half of people in the World each year. They are responsible for significant morbidity, mortality and healthcare costs. Their direct or indirect transmissions via water, food, air or inert surfaces depend on their aetiology (viral, bacterial or parasitic) and the local context. Bogotá and its region have several specificities: wastewater are often discharged into rivers without or after primary treatment only, the deposit in landfill of toilet papers and diapers soiled by excrement, and the low consumption of fruits and vegetables largely restricted to a handful of relatively cheap products that may be irrigated by surface freshwaters heavily contaminated with faeces. Our PhD aimed to assess the fluxes of some human enteric pathogens in the region of Bogotá and to try to relate these fluxes to the population health. The PhD combined three contributions. First, a method for culturing the human norovirus has been developed using isolated mouse intestinal villi as a cell model exhibiting the full diversity of intestinal epithelial cells. Several concentrations of trypsin were tested to activate noroviruses; the method was applied to faecal and environmental samples. Second, contamination with E. coli and some human enteric pathogens was monitored in water (landfill leachate, runoff water, river, irrigation water, drinking water), leafy vegetables eaten raw (chards) and air (above a landfill, in rural areas, in urban areas) in the Bogotá region. Third, the impact of socioeconomic contexts and individual practices (food, hygiene and health) on cases of acute gastroenteritis was assessed from surveys carried out in one district of Bogotá and analysed by various tools (principal component analysis, modelling …). We have shown that mouse isolated intestinal villi allow the infection and replication of human norovirus. The virus has to be activated with trypsin and has an average replicative cycle of 10 h. Villi are efficient in obtaining abundant biological material and are ideal for studying the biological activity of norovirus or for generating antibodies. They made it possible to see infectious noroviruses not detected by molecular method in several faeces and environmental samples; almost all samples positive by molecular method or immunodot-blot contain infectious noroviruses. At the regional level, the discharges of wastewater in the Bogotá and Balsillas rivers and in Tres Esquinas march contaminate the irrigation network of La Ramada area in the northwest of Bogotá with E. coli and potentially human enteric pathogens. Chards harvested in this area were heavily contaminated, in contrast to other growing areas. Their contamination evolved from their production to their purchase in nearby stores, washings increasing or decreasing their contamination, and handling on the merchant's stalls increasing contamination. The air was often contaminated with E. coli and Shigella spp.; it was not possible to detect a particular contribution of the Doña Juana landfill in pathogen aerosolization. The presence of Shigella spp. was observed in parallel in more than half of the stools of people with diarrhoea. Surveys have shown that the annual frequency of acute gastroenteritis decreases with increasing age; it seemed less common in households with elderly people, possibly due to stricter food hygiene practices. A transmission model of acute gastroenteritis distinguishing contamination from outside the households and contaminations between people in the same households did not show significant differences between neighbourhoods. Used to simulate numerical experiments, it suggests working on much higher numbers of surveys
La gastroenteritis aguda afecta entre una cuarta parte y la mitad de las personas en el mundo cada año. Son responsables de importantes costos de morbilidad, mortalidad y asistencia sanitaria. Sus transmisiones directas o indirectas a través del agua, alimentos, aire o superficies inertes dependen de su etiología (viral, bacteriana o parasitaria) y del contexto local. Bogotá y su región aledaña tienen varias especificidades: las aguas residuales a menudo se vierten a los ríos sin o solo después de un tratamiento primario, el depósito de papel higiénico y pañales sucios con excrementos son dispuestos generalmente en un relleno sanitario, y el bajo consumo de frutas y verduras restringido en gran medida a un puñado de productos relativamente baratos pueden ser irrigados por aguas dulces superficiales muy contaminadas con excrementos. Nuestra tesis doctoral tuvo como objetivo evaluar los flujos de algunos patógenos entéricos humanos en la región de Bogotá y tratar de relacionar estos flujos con la salud de la población. El doctorado combinó tres contribuciones. En primer lugar, se desarrolló un método para cultivar el norovirus humano utilizando vellosidades intestinales aisladas de ratón como modelo celular que exhibe la diversidad completa de células epiteliales intestinales. Se probaron varias concentraciones de tripsina para activar norovirus; el método se aplicó a muestras fecales y ambientales. En segundo lugar, se evidenció la contaminación de E. coli y patógenos entéricos humanos en el agua (lixiviados de vertedero, agua de escorrentía, río, agua de riego, agua potable), vegetales de hoja que se comen crudos (acelgas) y aire (sobre un vertedero sanitario, así como en áreas rurales y urbanas) en la región de Bogotá. En tercer lugar, se evaluó el impacto de los contextos socioeconómicos y las prácticas individuales (alimentación, higiene y salud) frente a los casos de gastroenteritis aguda a partir de encuestas realizadas en una localidad de Bogotá y analizadas mediante diversas herramientas (análisis de componentes principales, modelización…). Con este doctorado, hemos demostrado que las vellosidades intestinales aisladas de ratón permiten la infección y la replicación del norovirus humano. El virus debe activarse con tripsina y tiene un ciclo replicativo promedio de 10 h. Las vellosidades son eficaces para obtener abundante material biológico y son ideales para estudiar la actividad biológica de los norovirus o para generar anticuerpos. Ellas permitieron ver norovirus infecciosos no detectados por método molecular en varias heces y muestras ambientales; casi todas las muestras positivas por método molecular o inmunodot-blot contienían norovirus infecciosos. A nivel regional, los vertidos de aguas residuales en los ríos Bogotá y Balsillas y en el humedal Tres Esquinas contaminan la red de riego La Ramada en el noroeste de Bogotá con E. coli y potencialmete con patógenos entéricos humanos. Las acelgas recolectadas en esta área resultaron muy contaminadas, a diferencia de otras áreas de cultivo. Su contaminación evolucionó desde la producción hasta su compra en las tiendas cercanas, los lavados aumentaron o disminuyeron su contaminación y la manipulación en los puestos de comercio aumentaron la contaminación. El aire a menudo estaba contaminado con E. coli y Shigella spp., sin poder atribuir al relleno sanitario Doña Juana un rol particular. A su vez la presencia de Shigella spp. se observó en paralelo en más de la mitad de las deposiciones de personas con diarrea. Las encuestas demostraron que la frecuencia anual de gastroenteritis aguda disminuye respecto al aumento en edad; parecía menos común en hogares con personas mayores, posiblemente debido a prácticas de higiene alimentaria más estrictas. Un modelo de transmisión de gastroenteritis aguda que distinguió la contaminación fuera de los hogares y las contaminaciones entre personas dentro de los mismos hogares no mostró diferencias significativas entre vecindarios

碩士
國立中央大學
土木工程學系
103
In Taiwan, most irrigation water distribution depends on manual work, meanwhile, the water of irrigation and the lost from the conveyance can not be accurately calculated. This situation turns worse as the climate change leads to uneven rainfall. If the water usage in which accounts for 70% of water usage, can be allocated more precisely, it would improve water resource allocation effectivity. This study applies system dynamic model to establish irrigation water management model, combining rainfall and irrigated water, the model simulated two scenarios by decaeasing 30%, and 50% planned irrigation water in the wet year 2013. The result shows that field capacity of the end of the tested area, no. 5 round regin, will lower than wilting point, under 50% decreased water of irrigation plan. It appears that the original irrigation plan still have some extra reduction in the future. To probe the feasibility of automatic irrigation in the field, the model, built by this study, was used to estimate the demand of irrigation to the test area in the first crop, 2015. After sending to the cloud data center, the calculated flow will be acquired at the timing of every 2 hours by the automatic gate in the field, and the gate achieves flow adjustment in 1 hour. During testing period, because of the out flow always greater than 0.5 times of the inflow, the threshold set by this study for saving water, the gate can only operate under the target flow 0.46cms. However, the automatic operation result shows about 7.9 tons/day can be saved from the dynamic adjustment, and comparing to the target flow, only 526.5 tons water lost during the operating hour, with the error ratio being 1.79%. The contribution of this study provide the effectivity in water saving with the combination of accurate irrigation model and automatic adjustment gate.

The challenges facing small scale irrigation development in South Africa are varied and complex. This complexity is exacerbated by the many years of systematic neglect, in tandem with material and intellectual impoverishment of the majority of participants in this agricultural sector. Attempting to juggle sustainable development of small scale agriculture and environmental and socio-economic advancement is difficult, but there is sufficient evidence in the literature to suggest that small scale agriculture is increasing not only in South Africa but in Sub-Saharan Africa (Collier and Field, 1998) There is no doubt that this observed increase in irrigated communal gardens result from their increasingly important role of providing food security and as means of augmenting family income. Hence the government,NGO' s and other private sector organisations have increased their support for these small scale agricultural initiatives. Small scale agriculture is therefore increasingly becoming a common land use, and with this increased support, it is likely to become a major water user, particularly as it is located in close proximity to the water source. Hence both practices and processes for small scale agriculture require careful study. Irrigation practices have been studied in KwaZulu-Natal where small scale community gardens are continuously developing. The study included two locations near Pietermaritzburg. The first, at Willowfontein, involved irrigation by furrow , and the second, at Taylors Halt, involved irrigation by hand, using containers. The dynamics of the subsurface flow was monitored using tensiometry and modelled in detail using a two dimensional, soil physics model, Hydrus-2D, to evaluate the application efficiency. This study consisted of three parts viz: socio-economic system appraisal, technical measurement and monitoring, and modelling. Important findings obtained include the following: The highlighting of pertinent socio-economic issues governing water use and allocation and other operations in developing small scale agricultural conditions, including constraints to the development of this sector under the conditions described. The demonstration of the use of reasonably inexpensive, but sophisticated measuring techniques to observe the soil water processes in small scale community gardening practices. Accurate simulations of soil water infiltration,redistribution and uptake using the Hydrus2D model. With these successful simulations, together with the results of the social system appraisal, more efficient irrigation scenarios are proposed and evaluated. The development of a methodology that could be used to assess small scale irrigation efficiencies, with computer simulation models used as tools to conduct such an assessment.
Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

Stormwater runoff has negative impacts on water resources, human health and environment. In this research the effectiveness of Rain Water Harvesting (RWH) systems is examined as a stormwater Best Management Practice (BMP). Time-based, evapotranspiration-based, and soil moisture-based irrigation scheduling methods in conjunction with RWH and a control site without RWH were simulated to determine the effect of RWH as a BMP on a single-family residence scale. The effects of each irrigation scheduling method on minimizing water runoff leaving the plots and potable water input for irrigation were compared. The scenario that reflects urban development was simulated and compared to other RWH-irrigation scheduling systems by a control treatment without a RWH component. Four soil types (sand, sandy loam, loamy sand, silty clay) and four cistern sizes (208L, 416L, 624L, 833L) were evaluated in the urban development scenario. To achieve the purpose of this study; a model was developed to simulate daily water balance for the three treatments. Irrigation volumes and water runoff were compared for four soil types and four cistern sizes. Comparisons between total volumes of water runoff were estimated by utilizing different soil types, while comparisons between total potable water used for irrigation were estimated by utilizing different irrigation scheduling methods. This research showed that both Curve Number method and Mass-Balance method resulted in the greatest volumes of water runoff predicted for Silty Clay soil and the least volumes of water runoff predicted for Sand soil. Moreover, increasing cistern sizes resulted in reducing total water runoff and potable water used for irrigation, although not at a statistically significant level. Control treatment that does not utilize a cistern had the greatest volumes of predicted supplemental water among all soil types utilized, while Soil Moisture-based treatment on average had the least volume of predicted supplemental water.

Water resources for outdoor areas, such as lawns and landscapes, continues to become limited in many urban areas, especially in times of acute drought stress. Lawn species selection and cultural practices, such as mowing height, can strongly influence overall seasonal water needs. While previous research has reported various lawn species water use rates and differences in the ability of some cultivars to maintain green coverage during acute drought stress, little is known regarding the irrigation requirements of cool-season lawn species when using a deficit irrigation strategy based on a green coverage target threshold (e.g. 60-80% green) approach. Two greenhouse studies were conducted to screen various candidate species and seed mixtures in a sandy media. The highest water use and worst appearance/green coverage was associated with an inexpensive commercial lawn mixture; and the lowest water use and best appearance was generally associated with improved Kentucky bluegrass (Poa pratensis L.: KBG) cultivars. Field studies were conducted to quantify the irrigation requirements of drought susceptible (DS) and improved, drought tolerant (DT) KBG and tall fescue [Schedonorus arundinaceus (Schreb.): TF] cultivars, blends and mixtures at two mowing heights (5.1 or 8.9 cm). Results from a 74-day field study using a deficit irrigation replacement approach with a 70% green coverage threshold (GCT₇₀) irrigation trigger, demonstrated water savings of approximately 73 to 78% when using a DT TF (60.3 mm) as compared to 100% evapotranspiration (ET­_o) replacement (223.4 mm) and a conventional lawn irrigation approach (268.5 mm), respectively. The time to reach the GCT₇₀ generally ranked: TF=TF:KBG mixture>KBG and ranged from 18.0 days for DS ‘Right’ KBG and 52.5 days for DT ‘RainDance’ TF. Among TF and KBG cultivars using the GCT­₇₀ irrigation approach, DT TF required 35 to 68% less supplemental irrigation compared to DT and DS KBG cultivars (92.1 vs. 187.3 mm), respectively. Within KBG cultivars, the DT ‘Desert Moon’ required one-half the irrigation of DS Right (92.1 vs. 187.3 mm), while there were no differences among TF cultivars for irrigation needs. Mowing height did not affect KBG irrigation needs, but TF at 5.1 cm showed increased visual quality and green coverage, and significantly reduced irrigation requirements. Field research also compared species mixtures and blends using DS and DT KBG and TF to determine the amount of a DT species/cultivar that would enhance drought performance with ratios ranging from 25-100% DT as well as 90:10 TF:KBG mixtures. The quantity of a DT KBG in a blend, and DT TF in a TF:KBG mixture reduced irrigation needs, whereas the drought rating of the KBG cultivar in a TF:KBG mixture had no significant effect. In summary, these studies continue to demonstrate that significant supplemental lawn irrigation savings can be achieved by the selection of superior DT species and cultivars combined with a deficit irrigation replacement approach compared to other cool-season species and conventional irrigation practices.

碩士
國立臺灣大學
園藝暨景觀學系
105
The world faces the food and water crisis due to the increase of world population and the frequency of extreme weather happened. Agriculture plays a vital role in food production whereas agricultural irrigation water occupied 70% of world water usage. Large amount of water and nutrient would lost through leaching in the conventional agricultural irrigation practices. Crops plant with suitable environment and saving water irrigation practices could not only maintain production, or even increase productions in some crops, but also increase production quality. This study aimed to investigate the water use efficiency of vegetable crops that grow under different environments or irrigation practices. The climate and water resources are different between areas in the world. How to use water efficiently become important nowadays. The climate in Europe is more suitable for maize and wheat than other continents, therefore, Europe had the highest maize wheat water use efficiency. Moreover, applying partial root-zone drying irrigation (PRD) and regulated deficit irrigation (RDI) could higher the crop water use efficiency. Applying RDI75~50 or PRD50 on maize; PRD50 on pear; RDI100 and PRD75 on sorghum; PRD70 on potato; RDI100 on cotton; RDI50~70 on cabbage; PRD100 after reaching 65% full field capacity on hot pepper; RDI0 on lettuce; and PRD50 on tomato achieved the highest water use efficiency. Beta vulgaris L., Basella alba L. and Lactuca sativa L. grew under day/night temperature 30℃/25℃, 25℃/20℃ and 20℃/15℃ for 4 weeks. The results showed that there was no significant effect of crops late stage growing between different temperature treatments. Basella alba L. which is a C4 plant consumed the least water among three experimental crops. Moreover, it reached the highest WUEi, WUEyield and WUEbiomass under 30℃/25℃ environment. Beta vulgaris L. and Lactuca sativa L., which are C3 plants, had higher WUEi, WUEyield and WUEbiomass under 25℃/20℃ and 20℃/15℃ environment. C4 plants could achieve the higher water use efficiency under warm surroundings. Applying regulated deficit irrigation (RDI) practice with 100%, 70%, 50% and 30% irrigation amounts on Zea mays ‘Meichen’, Zea mays ‘Huachen’, Lactuca sativa L. sacriola L. var. sativa Bisch, Lactuca sativa L. var. capitata L. and Glebionis coronaria. The results showed that Zea mays ‘Meichen’ and Zea mays ‘Huachen’ reached the highest water use efficienct under RDI70 and PRD30 treatments respectively. Both of Lactuca sativa L. sacriola L. var. sativa Bisch and Lactuca sativa L. var. capitata L. reached the highest water use efficiency under RDI50 treatments. There was no significant difference between all of RDI treatments that was applied on Glebionis coronaria. Applying partial root-zone irrigation (PRD) practice with 100%, 70%, 50% and 30% irrigation amounts on Zea mays ‘Meichen’, Zea mays ‘Huachen’, Lactuca sativa L. sacriola L. var. sativa Bisch, Lactuca sativa L. var. capitata L. and Glebionis coronaria had the similar results as RDI treatments. Applying either RDI or PRD could higher crops water use efficiency.

博士
國立臺灣大學
農業工程學研究所
89
The wet-dry seasons are distinct in southern part of Taiwan. The mean annual rainfall in this area is 2,406 mm, however, only about 250 mm (10.4%) appears in the dry season from November to April. Although the reservoir capacity reaches 979.6×106 m3, its effectiveness is reduced due to sedimentation problems. As a result, flooding in wet seasons and drought in dry seasons often occur in this area. In this project, the Kang-Shan irrigation area of Kaohsiung Irrigation Association was selected. The background and water resource development process were first studied, and the soil and water utilization problems were discussed, then a series of agricultural water conservation plans were proposed in accordance with A-Kong-Tien revision project, as well as status changes. The feasibility of these plans was evaluated in an attempt to alleviate the flooding and drought problems. Finally, the Lu-Chu Scientific Park was taken as an example to show that, without new water sources, the agricultural water could assist industrial water by means of the measures as proposed in this study. Based on preliminary results, the projected water requirement of 2.6×104 tons could be supplied by return water, which was intercepted from upstream irrigation, diverted to farm ponds, stored, and stilled before use. Nevertheless, detailed procedures and cost estimation should be further studied.

This research included studies for transplant and field crop management with thepurpose of optimizing stand establishment, crop performance and nutritional quality ofartichoke (Cynara scolymus L.) grown in southwest Texas.Post-transplanting heat (35/20oC vs. 25/10oC, day/night temperatures) or drought[30% Water holding capacity (WHC) vs. 60% WHC] stress alone or in combinationsignificantly reduced shoot or/and root growth of artichoke seedlings. Combined heatand drought stresses strongly affected shoot water status and root growth. Results fromthis study imply that it is desirable to improve stand establishment by either conditioningthe seedlings to improve root growth or by preventing leaf dehydration by these stresses.Therefore, effects of plant growth regulators (PGR) on root growth and shoot waterstatus were examined.Ethylene regulators, including precursors or a releasing compound [DLmethionine(MET), 1-aminocyclopropane-1-carboxylic acid (ACC) and ethephone(ETH)], and inhibitors [amino-ethoxyvinylglycine (AVG) and 1-methylcyclopropene (1-MCP)] were applied to seedlings to evaluate their effect on root growth and development. ACC and ETH (1-100 M·L-1) enhanced root hair, root area and lateralroots (only with ETH at 30 M·L-1).The effects of film-forming antitranspirants and abscisic acid (ABA, 500-2000mg·L-1) foliar application on physiological responses, water status and hardiness ofartichoke transplants were examined under drought stress. ABA at 1000 mg·L-1enhanced drought tolerance of transplants which was associated with the maintenance ofshoot water status via stomatal closure. Film-forming antitranspirants were not effectiveto mitigate drought stress. These results suggest that ACC and ETH as root enhancers,and ABA as a plant water conditioner, could be useful PGR’s to enhance standestablishment in artichoke seedlings.Field artichoke performance in response to irrigation [50, 75 and 100% cropevapotranspiration (ETc)] and N (0-180 kg·ha-1) rates were investigated during threeseasons at Texas A&M AgriLife Research in Uvalde, TX. Irrigation was more effectivethan N rates to optimize artichoke yield. Yield reduction by 50% ETc was associatedwith a decrease in head number and weight. The highest yield was obtained with 100%ETc and 120 kg·ha-1 N. This study also showed that deficit irrigation significantlyimproved artichoke head quality, such as phenolic content, but with significant yieldlosses.

South Africa is a water scarce country. With the increasing demand of water from other users, irrigation, as the largest water user, has to find ways to produce more per drop and meet the food demands of the growing population. Enhancing the performance of smallholder irrigation schemes (SHI) is one way of saving water since they are fast becoming the largest water users in South Africa and the world over. Performance in the smallholder sub-sector is reportedly below the expectations of stakeholders. However, performance in smallholder irrigation schemes is multi-dimensional and can be looked at from different perspectives. This study assessed the technical performance of the Mooi River Irrigation Scheme (MRIS) from the technical managers` and the farmers` points of view and integrated them into one to derive a comprehensive set of best management practices (BMPs) for the scheme. This was done acknowledging that the farmer is now the water manager in line with Participatory Irrigation Management (PIM) and Irrigation Management Transfer (IMT). Three performance indicators related to water supply and delivery: conveyance efficiency, dependability of irrigation intervals between water applications and relative irrigation supply, and two agricultural performance indicators namely, output per unit irrigation supply and output per unit water consumed, were assessed during the spring and summer of the 2010/11 season. The field measurement method was used for the assessment of these indicators as opposed to the faster and more encompassing remote sensing method, due to resource constraints. The Velocity-area method was used to measure flow-rates in canals and crop water demands were estimated from FAO Cropwat 8.0 and Aquacrop 3.1. The results show an overall scheme conveyance efficiency of 86.4%, a maximum dependability of irrigation intervals between water applications of 2.57 in spring and a scheme relative irrigation supply of 1.48. Agricultural performance indicators, output per unit irrigation supply and water productivity per unit crop evapotranspiration (ET), were found to be 0.64 kg/m3 and 5.37 kg/m3 on average for cabbage, respectively. Farmers` satisfaction with taking an irrigation service can be used as a measure of the scheme`s performance. A questionnaire was administered among farmers to gather their views on the performance and to determine the factors that significantly influence their satisfaction status with taking the irrigation service at MRIS. Information collected from the questionnaire include age, gender, irrigation training, timeliness of water delivery, water distribution among the blocks, farming experience, farmer involvement in inspection of irrigation infrastructure and maintenance, among others. Farmers` were also asked for suggestions on improving the performance of their scheme. Their responses were analysed using a multinomial logit model. Results showed that 57% of the farmers are satisfied with using the irrigation service at MRIS, 30% are not satisfied, while 13% are neutral. Eight factors were found to be statistically significant in influencing the farmers` satisfaction status namely: location with respect to the water diversion point, location within a block from the main canal, age of the farmer, education level attained by the farmer, farming experience, the number of plots a farmer owns, fairness of water distribution across the blocks and the number of days a farmer accesses water The technical performance indicators assessed and the suggestions from the farmers on the way to improve performance of MRIS allowed the selection of the BMPs for the scheme. A set of seven BMPs based on farmer suggestions was derived. BMPs used as a guideline. The farmers were also tasked with the ranking of the derived BMPs according to their preference. The collected data was then ranked through an Analytic Hierarchy Process (AHP). The results show that establishment of and adherence to an irrigation schedule was the most preferred BMP by the farmers, while volumetric measurement of irrigation water used by each block was the least preferred. This study concludes that the performance of MRIS is comparable to other schemes and that farmers are aware of the problems bedevilling their scheme. It is also concluded that the performance of the scheme meets the farmers`, the key stakeholders, expectations and that irrigation scheduling is the most preferred BMP. The study recommends that farmers be more involved in performance assessments and management of their schemes. It is crucial to ensure that the recommended BMPs are acceptable to the farmers in the scheme. The best way to achieve this is by allowing farmers to participate in policy formulation and decision making.
Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.