Academic literature on the topic 'Irrigation Estimates'

A water use simulation for citrus (Citrus sinensis) was used to estimate the effects of climate, soil-available water, rooting depth, allowable depletion of available water, and partial coverage irrigation on the annual irrigation requirements. The soil in the study was excessively drained Candler sand (hyperthermic, uncoated Typic Quartzipsamments) of the Central Florida Ridge. Variation of annual rainfall from 667 to 1827 mm had a relatively small impact on annual irrigation requirements. Soil-available water, depth of root zone, and allowable depletion of available water all affected irrigation management and the number of irrigations annually. Simulated annual irrigation requirements varied over a wide range depending on the allowable depletion of soil-available water, irrigation depth, and the fraction of the land area that is irrigated. Effective rain estimated by the TR21 method during months of high rainfall was higher than estimates by the water budget. Monthly irrigation requirements varied seasonally and peaked in normally dry spring months of April and May. The irrigation simulation is a useful tool for examining the range of management strategies that can be considered for citrus.

Although irrigation is a common practice in pecan (Carya illinoinensis) orchards, the effects of different methods of irrigation on young tree growth, nut quality, and nutrient uptake have not been estimated. Five irrigation systems and one nonirrigated control system were established. Tree performance was characterized by change in trunk diameter, weight per nut, average kernel percentage, and total trunk diameter growth. Nutrient uptake was determined by foliar levels. The five irrigation systems were a microsprinkler with a 35-ft diameter, a microsprinkler with a 70-ft diameter, two subsurface driplines irrigating for 2 days/week alternating between water for 2 hours and no water for 2 hours, two subsurface driplines irrigating 1 day/week for 20 hours continuously (LI2), and four subsurface driplines irrigating for 10 hours continuously for 1 day/week (LI4). Irrigation systems affected foliar levels of potassium (K), boron (B), and manganese (Mn) levels. Irrigation system did not affect change in trunk diameter or kernel percentage. A spatial Durbin error model was estimated to use trunk diameter estimates from all trees in the orchard. This model found the trunk diameters of nonirrigated and LI4 system trees to be significantly less than those trees that were irrigated by the LI2 system. When observations were pooled over all years, LI4 trees had individual pecan nut weights that were significantly less than all other systems.

A quantitative microbial risk assessment model for estimating infection risks arising from consuming crops eaten raw that have been irrigated with effluents from stabilization ponds was constructed. A log-normal probability distribution function was fitted to a large database from a comprehensive monitoring of an experimental pond system to account for variability in Escherichia coli concentration in irrigation water. Crop contamination levels were estimated using predictive models derived from field experiments involving the irrigation of several crops with different effluent qualities. Data on daily intake of salad crops were obtained from a national survey in Brazil. Ten thousand-trial Monte Carlo simulations were used to estimate human health risks associated with the use of wastewater for irrigating low- and high-growing crops. The use of effluents containing 103–104E. coli per 100 ml resulted in median rotavirus infection risk of approximately 10−3 and 10−4 pppy when irrigating, respectively, low- and high-growing crops; the corresponding 95th percentile risk estimates were around 10−2 in both scenarios. Sensitivity analyses revealed that variations in effluent quality, in the assumed ratios of pathogens to E. coli, and in the reduction of pathogens between harvest and consumption had great impact upon risk estimates.

A multi-layer surface energy balance model was previously developed to estimate crop transpiration (T) and soil evaporation (E) in orchards partially wet by micro-irrigation systems. The model, referred to as SEB-PW, estimates latent (λE), sensible (H), and soil heat fluxes (G) and separates actual evapotranspiration (ETa) into dry and wet soil E and crop T. The main goal of this work was to evaluate the ability of the SEB-PW model to estimate ETa and analyze the diurnal and seasonal dynamics of E and T in two hazelnut (Corylus avellana L.) orchards irrigated by drip or micro-sprinkler systems. The assessment showed that simulated hourly ET was highly correlated with estimates from nearby weather stations and with measurements from micro-lysimeters (MLs). Hourly ET estimates were evaluated by root-mean-square error (RMSE), mean absolute error (MAE), the Nash–Sutcliffe coefficient (NSE), and the index of agreement (da), which equaled 58.6 W m−2, 35.6 W m−2, 0.85, and 0.94, respectively. Daily E estimates were also evaluated and equaled 0.27 mm day−1, 0.21 mm day−1, 0.87, and 0.94, respectively, and obtained a coefficient of determination (r2) of 0.85 when compared to the measurements from the MLs. Within a day of irrigation, E accounted for 28 and 46% of ET. In accordance with the obtained results, the proposed SEB-PW model improves estimates of soil E by allowing the wetted and non-wetted areas to be estimated separately, which could be useful for optimizing irrigation methods and practices in hazelnut orchards.

An automatic irrigation system was designed for use on green-house tomatoes growing in peat-based substrates. This system uses electronic tensiometers to monitor continuously substrate matric potential (SMP) in peat-bags. The system also uses the Penman equation to evaluate potential evapotranspiration (PET) through the acquisition of many greenhouse environmental parameters. Through a series of linear equations, estimates of PET are used in a computer-controller system to vary the electrical conductivity (EC) of irrigated nutrient solutions, as well as SMP setpoints at which irrigations are started. Such modifications to current irrigation management systems may improve fruit quality and reduce the risk of water stress during periods of high PET by irrigating more frequently with less-concentrated nutrient solutions. Conversely, during periods of low PET, irrigation is less frequent with more-concentrated nutrient solutions. Although no differences were found in fruit number or overall yield using variable nutrient solution EC, plant fresh weight was higher in those treatments. It is concluded that an integrated tensiometer-PET system may give increased precision to irrigation management and the control of crop growth in the greenhouse.

We compared transpiration estimates of three common desert landscape tree species using stem-flow gauges and lysimetry. Argentine mesquite (Prosopis alba Grisebach), desert willow [Chilopsis linearis (cav.) Sweet var. linearis], and southern live oak (Quercus virginiana Mill., seedling selection) were subjected to three irrigation regimes. Leaching fractions of +0.25, 0.00, and -0.25 were imposed for 2 years. During the summer of the second year, we conducted a comparative transpiration study. Trees growing in 190-liter plastic containers had a highly linear correlation (r = 0.98, P = 0.001) between transpiration estimated by stem-flow gauges and lysimetry. An average 18% error was measured between paired data (total runs of 14 to 72.5 hours) of stem-flow gauge and lysimetry transpiration estimates. However, a lower error was correlated significantly with longer run times (r = -0.37, P = 0.05). Based on field measurements taken in this experiment, run times would have to be >68 hours to maintain an associated error below 10%. Higher cumulative transpiration also was associated with longer run times (r = 0.80, P = 0.001). These results suggest that the stem-flow gauge can be used to estimate transpiration accurately to schedule irrigation for woody ornamental trees in an arid environment, provided that irrigation predictions are not based on short-term stem-flow gauge estimates (<68 hours).

Precise, accurate knowledge of percolation is key to reliable determination of soil water balance and a crop’s water-use efficiency. This work evaluated an approach to estimate the amount of water percolated in the root zone using soil water content (SWC) data measured at different time intervals. The approach was based on the difference of soil water content within and below the effective root zone of banana plants at different time intervals. A drainage lysimeter was used to compare the measured and estimated percolation data. The approach was then used in a banana orchard under drip and micro sprinkler irrigation, with and without the use of mulch. The soil water storage in the banana’s root zone was evaluated within a two-dimensional soil profile with time domain reflectometry (TDR). Mean percolation measured in the lysimeters did not differ from the approach’s estimates using intervals between SWC readings equal to or longer than 6 h from the end of an irrigation event. Percolation estimates under drip and micro sprinkler irrigation in the field, with and without mulch, were consistent with those measured in the lysimeters, considering the 6-h interval of SWC measurements. Percolation was greater under the drip irrigation system with mulch. The amount of water percolated was not influenced by the presence of mulch under the micro sprinkler system. Keywords: localized irrigation, soil water balance, soil water content sensor.

Reliable estimates of groundwater recharge are required for effective evaluation of management options for salinity control and high water-tables in the Riverine Plain of south-eastern Australia. This paper provides a brief description of the integrated surface and groundwater modelling approach used to estimate regional recharge rates and presents the recharge rates estimated for the Campaspe River Basin. The integrated model is a powerful management tool as it can predict the relationship between rainfall, irrigation, recharge and rises in the water-table levels. The model predicted that approximately 15% of irrigation water recharges the shallow aquifer. Approximately 6% of rainfall contributes to recharge in the irrigated areas while 4 to 5% of rainfall becomes recharge in the dryland areas. Rainfall makes a greater contribution in the irrigation areas compared to the dryland areas because irrigation predisposes the soil to recharge from rainfall. The water-table levels in the irrigation areas are currently rising at approximately 0.14 m yr-1. This rate of rise will increase faster than the increase in irrigation applications.

Summary. Sustainable irrigation guidelines that maximise profitability and minimise water losses and accession to the watertable are required for the new Ord Sugar Industry. In addition, knowledge on crop water requirements is needed to guide water allocation and costing policies for the expanding Ord Irrigation Area where sugarcane is likely to be a dominant crop. Field data indicating water requirements for sugar in the Ord Irrigation Area are few and this paper deploys a modelling approach to extrapolate from knowledge of water requirements in other parts of the world. The approach links long-term climatic data with soil water characteristics of the main soil type, with a cropping systems model, to develop indicative estimates of irrigation water requirement and yield consequences for different management options for sugarcane production in the Ord. Analyses of the growth of 12-month old ratoon crops were conducted using the APSIM–Sugarcane model with historical climatic data from 1960 to 1985 and either a deep (188 mm available water to 160 cm depth) or shallow (144 mm of water to 120 cm depth) Cununurra clay soil. Under maximum attainable growth conditions where crops were irrigated after half the soil water supply was depleted, average sucrose yield ranged from 26.7 to 29.0 t/ha, and the irrigation requirement (assuming 100% application efficiency) ranged from 22.7 to 23.8 ML/ha depending on ratooning date. Soil water holding capacity had a major effect on the number of irrigations and the interval between irrigation for a given irrigation schedule but little effect on yield or irrigation requirement. Varying the irrigation schedule by changing the level of soil water depletion before irrigation and thus the irrigation frequency, showed the tradeoff between yield and irrigation requirement with the most profitable irrigation schedule depending on the price of sucrose and the cost of irrigation relative to other costs. Most of the year-to-year variation in irrigation water requirement could be explained by the highly variable effectiveness in soil storage of rainfall which ranged from 44 to 93%. This study has provided insight and indicative estimates of the yield and irrigation requirements for different irrigation management options for use in the establishment of an Ord River sugar industry. These estimates will be further refined as field data become available.

Irrigation scheduling, by keeping track of irrigation applications, soil storage and crop water use, has been computerized by a number of different individuals. A key component of the computerized methods is the estimation of a reference crop evapotranspiration rate. Complaints about one such method, AZSCHED, led the authors to compare the reference crop evapotranspiration values calculated by AZSCHED with those calculated by a second procedure available used by AZMET. Results of the comparison indicated that no significant difference existed between methods, for either a traditionally "long season", or a contemporary "short season" growing period. AZSCHED did estimate crop water use to be about 5% - 8% more than AZMET, an amount that is not of importance considering the irrigation inefficiencies created by field non-uniformities. Experience by the authors indicates that inappropriate selection of irrigation efficiencies and/or soil water holding capacity may be the main cause of user complaints.

El reg és el principal consum antropogènic d'aigua dolça. Es preveu que l'explotació dels recursos hídrics per a millorar la producció d'aliments mitjançant pràctiques de reg seguirà augmentant en els propers decennis. De fet, es preveu que el creixement demogràfic i els canvis climàtics exerceixin una pressió encara més gran sobre els recursos hídrics disponibles. Tot i que el reg té conseqüències directes en la gestió racional dels recursos hídrics, així com en la producció d'aliments, cal un coneixement detallat dels llocs en què realment es rega a tot el món i de quanta aigua s'utilitza realment per les pràctiques de reg. En aquesta investigació s'han elaborat mètodes per detectar i cartografiar les zones on realment es rega, així com mètodes per estimar les quantitats d'aigua que s'apliquen per al reg; les metodologies proposades utilitzen dades d'humitat del sòl provinents de la teledetecció espacial. En aquesta investigació s'han adoptat dos casos d'estudi: el primer es troba a la conca de l'Ebre, al nord-est d'Espanya, mentre que l'altre és la conca de l'Alt Tíber, a Itàlia central. S'han assajat diversos productes d'humitat del sòl obtinguts per teledetecció amb diferents resolucions espacials per avaluar els que millor funcionen en la detecció de reg i, per tant, en la cartografia de les zones de regadiu. A més, s'han realitzat estimacions quantitatives de les quantitats d'aigua aplicades per al reg. L'activitat de detecció i cartografia del reg s'ha dut a terme en els dos casos d'estudi. En l'espanyol s'ha avaluat inicialment la capacitat de detecció de reg de diversos productes de teledetecció. S'han avaluat els següents jocs de dades d'humitat del sòl: SMAP (Soil Moisture Active Passive) a 1 km i 9 km, SMOS (Soil Moisture and Ocean Salinity) a 1 km, Sentinel-1 a 1 km, i ASCAT (Advanced SCATterometer) a 12,5 km. Les versions d'1 km de SMAP i SMOS s'obtenen mitjançant la desagregació amb el mètode DISPATCH (DISaggregation based on Physical And Theoretical scale CHange). La detectabilitat del reg pels productes considerats s'ha avaluat mitjançant índexs derivats de la teoria d’estabilitat temporal aquí utilitzada sota aquesta nova perspectiva. A més, s'han elaborat mapes de les zones irrigades produïts a través de l'algoritme d'agrupament K-mitjanes. A les zones agrícoles de la conca de l'Alt Tíber, a Itàlia, s'ha realitzat una anàlisi a doble escala. En l'anàlisi a 1 km de resolució espacial s'ha aplicat el mateix procediment adoptat en el cas d'estudi de la conca de l'Ebre per avaluar la detectabilitat del regadiu mitjançant la humitat del sòl provinent de la teledetecció. S'han utilitzat els següents productes: SMAP a 1 km, la versió Sentinel-1 a 1 km publicada pel Copernicus Global Land Service, i una versió Sentinel-1 a escala de la parcel·la (produïda per THEIA) agregada a 1 km. Cal observar que els dos primers productes són els mateixos que també s’han utilitzat en el cas d'estudi espanyol. En aquesta anàlisi, així com en la realitzada sobre l'àrea d'estudi a la conca de l'Ebre, s'ha utilitzat com a suport el model de superfície continental SURFEX-ISBA (Surface EXternalisée - Interaction Sol Biosphère Atmosphère). En l'anàlisi a escala de parcel·la, les dades de THEIA Sentinel-1 agregades a 100 m s'han utilitzat per produir mapes d'alta resolució de les zones de regadiu mitjançant l'algoritme d'agrupament K-mitjanes. L'activitat de quantificació del reg s'ha dut a terme a la zona d'estudi a la conca de l'Ebre únicament; s'han realitzat dos experiments: un utilitzant SMAP amb dades a 1 km de resolució i un altre utilitzant SMOS amb dades a 1 km. Tots dos conjunts de dades s'han utilitzat per forçar l'algoritme SM2RAIN adaptat a l'estimació del reg. En l'algoritme s'ha aplicat una modelització més realista del terme d’evapotranspiració per reproduir adequadament l'evapotranspiració dels cultius segons el model de la FAO (Organització de les Nacions Unides per a l'Agricultura i l'Alimentació). Les anàlisis realitzades tenen per objecte satisfer les llacunes existents en el camp de la recerca relacionada amb el reg; els resultats obtinguts són útils per avaluar l'impacte de les pràctiques de reg en el cicle hidrològic.
El riego es el principal consumo antropogénico de agua dulce. Se prevé que la explotación de los recursos hídricos para mejorar la producción de alimentos mediante prácticas de riego seguirá aumentando en los próximos decenios. De hecho, se prevé que el crecimiento demográfico y los cambios climáticos ejerzan una presión aún mayor sobre los recursos hídricos disponibles. A pesar de que el riego tiene consecuencias directas en la gestión racional de los recursos hídricos, así como en la producción de alimentos, falta un conocimiento detallado de los lugares en los que realmente se riega en todo el mundo y de cuánta agua se utiliza realmente para las prácticas de riego. En esta investigación se han elaborado métodos para detectar y cartografiar las zonas donde realmente se riega, así como métodos para estimar las cantidades de agua que se aplican para el riego; las metodologías propuestas utilizan datos de humedad del suelo provenientes de la teledetección espacial. En esta investigación se han adoptado dos casos de estudio: el primero se sitúa en la cuenca del Ebro, en el noreste de España, mientras que el otro es la cuenca del Alto Tíber, en Italia central. Se han ensayado varios productos de humedad del suelo obtenidos por teledetección con diferentes resoluciones espaciales para evaluar los que mejor funcionan en la detección del riego y, por lo tanto, en la cartografía de las zonas de regadío. Además, se han realizado estimaciones cuantitativas de las cantidades de agua aplicadas para el riego. La actividad de detección y cartografía del riego se ha llevado a cabo en ambos casos de estudio. En el español se ha evaluado inicialmente la capacidad de detección de riego de varios productos de teledetección. Se han evaluado los siguientes conjuntos de datos de humedad del suelo: SMAP (Soil Moisture Active Passive) a 1 km y 9 km, SMOS (Soil Moisture and Ocean Salinity) a 1 km, Sentinel-1 a 1 km, y ASCAT (Advanced SCATterometer) a 12,5 km. Las versiones de 1 km de SMAP y SMOS se obtienen mediante la desagregación con el método DISPATCH (DISaggregation based on Physical And Theoretical scale Change). La detectabilidad del riego por los productos considerados se ha evaluado mediante índices derivados de la teoría de la estabilidad temporal aquí utilizada bajo esta nueva perspectiva. Además, se han elaborado mapas de las zonas irrigadas producidos a través del algoritmo de agrupamiento K-medias. En las zonas agrícolas de la cuenca del Alto Tíber, en Italia, se ha realizado un análisis a doble escala. En el análisis a 1 km de resolución espacial, se ha aplicado el mismo procedimiento adoptado en el caso de estudio de la cuenca del Ebro para evaluar la detectabilidad de la irrigación mediante la humedad del suelo por teledetección. Se han utilizado los siguientes productos: SMAP a 1 km, la versión Sentinel-1 a 1 km entregada por el Copernicus Global Land Service, y una versión Sentinel-1 a escala de parcela (producida por THEIA) agregada a 1 km. Obsérvese que los dos primeros productos son los mismos que también se utilizaron en el caso de estudio español. En este análisis, así como en el realizado sobre el área de estudio en la cuenca del Ebro, se ha utilizado como soporte el modelo de superficie terrestre SURFEX-ISBA (SURface EXternalisée - Interaction Sol Biosphère Atmosphère). En el análisis a escala de parcela, los datos del THEIA Sentinel-1 agregados a 100 m se han utilizado para producir mapas de alta resolución de las zonas de regadío mediante el algoritmo de agrupamiento K-medias. La actividad de cuantificación del riego se ha llevado a cabo en la zona de estudio de la cuenca del Ebro únicamente; se han realizado dos experimentos: uno explotando SMAP con datos a 1 km de resolución y otro explotando SMOS con datos a 1 km. Ambos conjuntos de datos se han utilizado para forzar el algoritmo SM2RAIN adaptado a la estimación del riego. En el algoritmo se ha aplicado una modelización más realista del término de evapotranspiración para reproducir adecuadamente la evapotranspiración de los cultivos según el modelo de la FAO (Organización de las Naciones Unidas para la Agricultura y la Alimentación). Los análisis realizados tienen por objeto colmar las lagunas existentes en el campo de la investigación relacionada con el riego; los resultados obtenidos son útiles para evaluar el impacto de las prácticas de riego en el ciclo hidrológico.
Irrigation is the primary source of anthropogenic freshwater consumptions. The exploitation of water resources to improve the food production through irrigation practices is expected to further increase in the upcoming decades. In fact, the population growth and climate changes are expected to put even more pressure on the available water resources. Despite irrigation having direct implications on the rational management of water resources, as well as on food production, a detailed knowledge of where irrigation actually occurs worldwide and of how much water is actually used for irrigation practices is missing. In this research, approaches to detect and map areas where irrigation actually occurs, as well as methods to estimate the amounts of water applied for irrigation, have been developed; the proposed methodologies exploit remote sensing soil moisture. Two case studies have been considered in this research: the first one is located within the Ebro basin, in North-eastern Spain, while the other one is the Upper Tiber basin, in central Italy. Several remotely sensed soil moisture products at different spatial resolutions have been tested to evaluate the best performing ones in detecting irrigation signals and thus mapping irrigated areas. In addition, quantitative estimates of the water amounts applied for irrigation have been performed. The irrigation detection and mapping activity has been carried out over both case studies. In the Spanish one, the capability to detect irrigation of several remote sensing products has been initially assessed. The following soil moisture data sets have been evaluated: SMAP (Soil Moisture Active Passive) at 1 km and 9 km, SMOS (Soil Moisture and Ocean Salinity) at 1 km, Sentinel-1 at 1 km, and ASCAT (Advanced SCATterometer) at 12.5 km. The 1 km versions of SMAP and SMOS are obtained through downscaling with the DISPATCH (DISaggregation based on Physical And Theoretical scale CHange) method. The detectability of irrigation by the considered products has been assessed through indices derived from the temporal stability theory here used under this new perspective. Furthermore, maps of irrigated areas have been produced through the K-means clustering algorithm. Over the agricultural areas in the Upper Tiber basin, in Italy, a double-scale analysis has been carried out. In the analysis at 1 km spatial resolution, the same procedure adopted over the case study in the Ebro basin to evaluate the detectability of irrigation through remotely sensed soil moisture has been applied. The following products have been used: SMAP at 1 km, the Sentinel-1 at 1 km version delivered by the Copernicus Global Land Service, and a plot-scale-born Sentinel-1 version (produced by THEIA) aggregated at 1 km. Note that the first two products are the same used over the Spanish case study also. In this analysis, as well as in the one carried out over the study area in the Ebro basin, surface soil moisture simulated by the SURFEX-ISBA (SURface EXternalisée - Interaction Sol Biosphère Atmosphère) land surface model has been used as support. In the plot-scale analysis, THEIA Sentinel-1 data aggregated at 100 m have been used to produce high-resolution maps of irrigated areas through the K-means clustering algorithm. The irrigation quantification activity has been carried out over the study area in the Ebro basin only; two experiments have been performed: one exploiting SMAP at 1 km data and another one exploiting SMOS at 1 km data. Both data sets have been used to force the SM2RAIN algorithm adapted to estimate irrigation. A more realistic modeling of the evapotranspiration term has been implemented into the algorithm to properly reproduce the crop evapotranspiration according to the FAO (Food and Agriculture Organization) model. The analyses carried out are aimed at filling the existing gaps in the irrigation-related research field; the obtained results are useful to assess the impact of irrigation practices on the hydrological cycle.
L’irrigazione è la principale fonte di consumo di acqua dolce. Nei prossimi decenni è atteso un ulteriore sfruttamento della risorsa idrica per incrementare la produzione di cibo attraverso le pratiche irrigue. Si stima infatti che la crescita della popolazione e i cambiamenti climatici possano esercitare una pressione ancora maggiore sulle risorse idriche disponibili. Nonostante le importanti implicazioni che ha l’irrigazione sulla gestione razionale dell’acqua e sulla produzione di cibo, non si ha una conoscenza dettagliata di dove l’irrigazione effettivamente avvenga nel mondo e di quanta acqua venga effettivamente utilizzata per le pratiche irrigue. In questa ricerca sono stati sviluppati approcci per rilevare e mappare le aree dove effettivamente si verifica l’irrigazione e per stimare i volumi irrigui; le metodologie proposte sfruttano l’umidità del suolo rilevata da satellite. In questa ricerca sono stati considerati due casi di studio: il primo si trova nel bacino del fiume Ebro, nel Nord-Est della Spagna, mentre l’altro è il bacino superiore del Tevere, nell’Italia centrale. Diversi prodotti di umidità del suolo da satellite, caratterizzati da diverse risoluzioni spaziali, sono stati valutati al fine di determinare i più performanti nel rilevare segnali di irrigazione e quindi mappare le aree irrigate. Inoltre, sono state eseguite stime quantitative dei volumi di acqua utilizzati per pratiche irrigue. L’attività di rilievo e mappatura dell’irrigazione è stata condotta su entrambe le aree pilota. In quella spagnola, è stata valutata la capacità di rilevare l’irrigazione di diversi prodotti di umidità del suolo. Sono stati considerati i seguenti set di dati: SMAP (Soil Moisture Active Passive) a 1 km e 9 km, SMOS (Soil Moisture and Ocean Salinity) a 1 km, Sentinel-1 a 1 km e ASCAT (Advanced SCATterometer) a 12.5 km. Le versioni a 1 km di SMAP e SMOS sono ottenute tramite disaggregazione eseguita con il metodo DISPATCH (DISaggregation based on Physical And Theoretical scale CHange). La capacità di rilevare l’irrigazione da parte dei prodotti considerati è stata valutata tramite indici derivanti dalla teoria della stabilità temporale e usati in questo studio sotto una nuova prospettiva. Inoltre, sono state prodotte delle mappe delle aree irrigate attraverso l’algoritmo di classificazione K-means. Un’analisi a doppia scala spaziale è stata condotta sulle aree agricole all’interno del bacino superiore del Tevere, in Italia. Nell’ambito dell’analisi alla risoluzione spaziale di 1 km, è stata applicata la stessa procedura già adottata per il caso di studio nel bacino dell’Ebro per valutare la possibilità di rilevare l’irrigazione tramite umidità del suolo da satellite. Sono stati utilizzati i seguenti prodotti: SMAP a 1 km, la versione a 1 km di Sentinel-1 fornita da Copernicus Global Land Service e una versione di Sentinel-1 originariamente prodotta de THEIA alla scala di parcella e aggregata a 1 km. Va sottolineato che i primi due prodotti menzionati sono stati utilizzati anche sull’area pilota in Spagna. Sia in questa analisi che in quella condotta nel bacino dell’Ebro, dati di umidità del suolo superficiale modellati tramite il modello di superficie terrestre SURFEX-ISBA (SURface EXternalisée - Interaction Sol Biosphère Atmosphère) sono stati utilizzati come supporto. Nell’analisi alla scala di parcella, sono stati impiegati i dati di Sentinel-1 prodotti da THEIA e aggregati a 100 m al fine di produrre mappe di aree irrigate ad alta risoluzione tramite l’algoritmo di classificazione K-means. L’attività di quantificazione dell’irrigazione è stata finalizzata solamente per l’area pilota nel bacino dell’Ebro; sono stati condotti due esperimenti: uno utilizzando i dati da SMAP a 1 km e un altro sfruttando i dati da SMOS a 1 km. Entrambi i set di dati sono stati utilizzati per forzare la versione dell’algoritmo SM2RAIN adattata per la stima dell’irrigazione. Una modellazione più realistica dell’evapotraspirazione è stata implementata nell’algoritmo al fine di riprodurre adeguatamente l’evapotraspirazione delle colture secondo il modello FAO (Food and Agriculture Organization). Le analisi condotte sono finalizzate a colmare le lacune esistenti nel campo di ricerca relativo all’irrigazione; i risultati ottenuti sono utili per valutare l’impatto delle pratiche irrigue sul ciclo idrologico.

Os projetos hidráulicos para sistemas de irrigação por gotejamento, geralmente, desprezam as perdas de carga localizadas devido ao ressalto resultante da conexão dos gotejadores nas linhas laterais, ou então, estabelecem coeficientes médios ou taxas percentuais para o cálculo destas perdas. No entanto, essas perdas localizadas podem ser bastante significativas, variando com a vazão e a relação modelo do gotejador com diâmetro da tubulação instalada. Esta dissertação apresenta os resultados de uma pesquisa experimental para determinar uma relação matemática que permita estimar as perdas de carga localizadas para cada conjunto gotejador - tubo. Esta relação matemática associa os coeficientes de resistência de carga cinética, em diferentes vazões, com índices geométricos de obstrução para quatro seções, circulares e levemente ovais, de diferentes tubos de polietileno e, quatro modelos de gotejadores, todos comercializados na região de Ribeirão Preto. Abordaram-se ainda aspectos do uso da equação de Blasius para cálculo das perdas de carga distribuída e a influência da variação da viscosidade no escoamento.
The hydraulic projects to drip irrigation systems, usually disregard the localized head losses because of the destach of the drip\'s connection in the lateral lines, or establish average coefficients or percentual rates to calculate these losses. However, these localized losses can be rather significant, varying according to the flow and the drip\'s model connection with the diameter of the installed tubing. This dissertation presents the results of an experimental research to determine a mathematical relation that allows us to estirnate the localized head losses to each drip group - tube. This mathematical relation associates the resistance of kinetic head, in different flows, with geometrical contents of obstruction to four sections, circular and slightly oval, from different polietilene tubes, and four models of drips, commercialized in Ribeirão Preto\'s region. It\'s also discussed the aspects of the usage of Blasius equation to calculate the losses of distributed head and the influence of viscosity variation during the drain.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The present work had for objective to develop a simple process, with low cost and enough precise for its use in irrigation systems. The measurer consists of a secondary canalization provided with a hydrometer of low outflow installed in parallel with a singularity capable to provoke a pressure difference enters the extreme points of the device. The distinguishing pressure induces to the partial draining of the water through the secondary canalization being measured for the hydrometer. The work was developed in the Irrigation, Hydraulical and Draining laboratory of the Department of Agricultural Engineering of the Federal University of Santa Maria and in a system of water main for a central pivot installed in the Mayã Farm, in the city of São Sepé - RS. The work consists in the evaluation of a proportional measurer of volume (or outflow) and of the posterior application for the estimate of the volume of water fed for the system of bombardment to an expository of a system of irrigation of the type central pivot. The proportional measurer presents easiness about the construction and installation in the field. The results allowed concluding that the proportional measurer was capable to estimate the outflow of the central pivot irrigation system. The proportional measurer can be installed and operated in a simple way, and its components are of easy acquisition and low cost and maintenance. Such characteristics assume great importance in the current days becoming viable the implantation of systems of measurement in all the existing systems of irrigation in the agricultural way.
O presente trabalho teve por objetivo desenvolver um processo simples, de baixo custo e suficientemente preciso para a sua utilização em sistemas de irrigação. O medidor consiste de uma canalização secundária provida de um hidrômetro de baixa vazão instalada em paralelo com uma singularidade capaz de provocar uma diferença de pressão entre os pontos extremos do dispositivo. A pressão diferencial induz ao escoamento parcial da água através da canalização secundária sendo medida pelo hidrômetro. O trabalho foi desenvolvido no laboratório de Hidráulica, Irrigação e Drenagem do Departamento de Engenharia Rural da Universidade Federal de Santa Maria e em um sistema de bombeamento para adução de água para um pivô central na instalado na Fazenda Mayã, município de São Sepé RS. O trabalho consta da avaliação de um medidor de volume (ou de vazão) proporcional e da posterior aplicação para a estimativa do volume de água alimentado pelo sistema de bombeamento a uma adutora de um sistema de irrigação do tipo pivô central. O medidor proporcional apresenta facilidade quanto à sua construção e instalação no campo. Os resultados obtidos permitiram concluir que o medidor proporcional foi capaz de estimar com precisão a vazão da adutora de alimentação de um sistema de irrigação do tipo pivô central. O medidor proporcional pode ser instalado e operado de modo simples, sendo que seus componentes são de fácil aquisição e de baixo custo e manutenção. Tais características assumem grande importância nos dias atuais contribuindo para a implantação de sistemas de medição em todos os sistemas de irrigação existentes no meio rural.

GONÇALVES, Fabricio Mota. Evapotranspiração e coeficientes de cultivo (KC) da cana-de-açúcar irrigada por gotejamento subsuperficial. 2010. 64 f. Dissertação (Mestrado em engenharia agrícola)- Universidade Federal do Ceará, Fortaleza-CE, 2010.
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Sugar cane is one of the crops with the highest level of water consumption, with a high evapotranspiration demand throughout most of its cycle. Knowledge of the sugar cane water demand, the time that irrigation should be applied, and how to irrigate the crop are becoming increasingly important for the sustainable development of irrigated sugar cane cultivation, especially in areas of low water availability, as it is the case in northea stern Brazil. The experiment was carried out at the Curu Experimental Field (property of the Embrapa Tropical Agroindustry), located in the Curu-Paraipaba Irrig ation Project, city of Paraipaba-CE (3 ° 29 '20''S, 39 ° 9' 45''W and elevation 30m), in order to determine the evapotrans piration and crop coefficients (Kc) of sugarcane (Saccharum L. officinarium), subsurface drip-irrigated. It was used the SP 6949 sugar cane variety, planted in a spacing of 1.8 m between double rows and 0.4 m between rows within the double row. As to t he irrigation, we used one lateral water line for each double row, buried at a depth of 0.15 m, w ith self-compensating drip emitters, with a flow rate of 1 L h-1, spaced 0.5 m on the water line. The crop was irrigated daily and there were three fertigations per week. The irrigation de pth was periodically adjusted, keeping the soil water potential between -8 kPa to -20 kPa. The crop evapotranspiration (ETc) was determined using a wei ghing lysimeter with a surface area of 2.25 m 2. The reference evapotranspiration (ETo) was estimated by the FAO Penman-Monteith method. The durations of the phenological stages of cane sugar were estimated through analysis of soil cover, with the use of digital images. Durations of 31, 49, 237 and 118 days were observed, respectively for initial, crop development, mid-season and late season stages. The yields achieved within and outside the lysimeter were respectively 144.4 and 108.8 t ha -1 . The total ETc observed during the cycle of the sugar cane was 1074.1 m m, with maximum values of 6.6 mm d-1 during the mid-season stage. Observed Kc values for initial, mid-season and late season stages were respectively 0.23, 1 .03 and 0.50. In the crop development stage, the relationship between Kc and the (crop) soil cover was represented with good accuracy by a negative quadratic model.
A cana-de-açúcar é uma das culturas com maior consumo de água, apresentando uma alta demanda evapotranspirativa ao longo da maior parte do seu ciclo. O conhecimento das necessidades hídricas da cana-de-açúcar, do momento de aplicação da água requerida pela mesma e a forma de aplicação torna-se cada vez mais importante para o desenvolvimento sustentável da sua produção irrigada, principalmente em regiões de pouca disponibilidade hídrica, como é o caso da região Nordeste do Brasil. O experimento foi conduzido no Campo Experimental do Curu, pertencente à Embrapa Agroindústria Tropical localizado no Perímetro Irrigado Curu-Paraipaba, município de Paraipaba-CE (3° 29’ 20’’ S, 39° 9’ 45’’ W e altitude de 30 m), com o objetivo de determinar a evapotranspiração e os coeficientes de cultivo (Kc) da cana-de-açúcar (Saccharum officinarium L.), irrigada por gotejamento subsuperficial. Utilizou-se a variedade de cana SP 6949, plantada no espaçamento de 1,8 m entre fileiras duplas e 0,4 m entre linhas dentro da fileira dupla. Na irrigação utilizou-se uma linha lateral para cada fileira dupla, enterrada na profundidade de 0,15 m, com gotejadores autocompensantes, com vazão de 1 L h-1, espaçados de 0,5 m na linha. A cultura foi irrigada com freqüência diária e foram realizadas três fertirrigações por semana. A lâmina de irrigação foi ajustada periodicamente, mantendo-se o potencial de água no solo entre -8 kPa e -20 kPa. A evapotranspiração da cultura (ETc) foi determinada utilizando-se um lisímetro de pesagem com área superficial de 2,25 m2. A evapotranspiração de referência (ETo) foi estimada pelo método FAO Penman-Monteith. As durações das fases fenológicas da cana-de-açúcar foram estimadas por meio da análise da cobertura do solo pela cultura, determinada com o uso de imagens digitais. Foram observadas durações de 31, 49, 237 e 118 dias, para as fases inicial, de desenvolvimento, intermediária e final, respectivamente. A produtividade alcançada dentro e fora do lisímetro foi de 144,4 e 108,8 t ha-1, respectivamente. A ETc total observada durante o ciclo da cana-de-açúcar foi de 1.074,1 mm, com valores máximos da ordem de 6,6 mm d-1 durante a fase intermediária. Foram observados valores de Kc iguais a 0,23, 1,03 e 0,50, para as fases inicial, intermediária e final, respectivamente. Na fase de desenvolvimento vegetativo a relação entre o Kc e a cobertura do solo pela cultura foi representada com bastante exatidão por um modelo quadrático negativo.

Irrigation is the primary source of anthropogenic freshwater consumptions. The exploitation of water resources to improve the food production through irrigation practices is expected to further increase in the upcoming decades. In fact, the population growth and climate changes are expected to put even more pressure on the available water resources. Despite irrigation having direct implications on the rational management of water resources, as well as on food production, a detailed knowledge of where irrigation actually occurs worldwide and of how much water is actually used for irrigation practices is missing. In this research, approaches to detect and map areas where irrigation actually occurs, as well as methods to estimate the amounts of water applied for irrigation, have been developed; the proposed methodologies exploit remote sensing soil moisture. Two case studies have been considered in this research: the first one is located within the Ebro basin, in North-eastern Spain, while the other one is the Upper Tiber basin, in central Italy. Several remotely sensed soil moisture products at different spatial resolutions have been tested to evaluate the best performing ones in detecting irrigation signals and thus mapping irrigated areas. In addition, quantitative estimates of the water amounts applied for irrigation have been performed. The irrigation detection and mapping activity has been carried out over both case studies. In the Spanish one, the capability to detect irrigation of several remote sensing products has been initially assessed. The following soil moisture data sets have been evaluated: SMAP (Soil Moisture Active Passive) at 1 km and 9 km, SMOS (Soil Moisture and Ocean Salinity) at 1 km, Sentinel-1 at 1 km, and ASCAT (Advanced SCATterometer) at 12.5 km. The 1 km versions of SMAP and SMOS are obtained through downscaling with the DISPATCH (DISaggregation based on Physical And Theoretical scale CHange) method. The detectability of irrigation by the considered products has been assessed through indices derived from the temporal stability theory here used under this new perspective. Furthermore, maps of irrigated areas have been produced through the K-means clustering algorithm. Over the agricultural areas in the Upper Tiber basin, in Italy, a double-scale analysis has been carried out. In the analysis at 1 km spatial resolution, the same procedure adopted over the case study in the Ebro basin to evaluate the detectability of irrigation through remotely sensed soil moisture has been applied. The following products have been used: SMAP at 1 km, the Sentinel-1 at 1 km version delivered by the Copernicus Global Land Service, and a plot-scale-born Sentinel-1 version (produced by THEIA) aggregated at 1 km. Note that the first two products are the same used over the Spanish case study also. In this analysis, as well as in the one carried out over the study area in the Ebro basin, surface soil moisture simulated by the SURFEX-ISBA (SURface EXternalisée - Interaction Sol Biosphère Atmosphère) land surface model has been used as support. In the plot-scale analysis, THEIA Sentinel-1 data aggregated at 100 m have been used to produce high-resolution maps of irrigated areas through the K-means clustering algorithm. The irrigation quantification activity has been carried out over the study area in the Ebro basin only; two experiments have been performed: one exploiting SMAP at 1 km data and another one exploiting SMOS at 1 km data. Both data sets have been used to force the SM2RAIN algorithm adapted to estimate irrigation. A more realistic modeling of the evapotranspiration term has been implemented into the algorithm to properly reproduce the crop evapotranspiration according to the FAO (Food and Agriculture Organization) model. The analyses carried out are aimed at filling the existing gaps in the irrigation-related research field; the obtained results are useful to assess the impact of irrigation practices on the hydrological cycle. L’irrigazione è la principale fonte di consumo di acqua dolce. Nei prossimi decenni è atteso un ulteriore sfruttamento della risorsa idrica per incrementare la produzione di cibo attraverso le pratiche irrigue. Si stima infatti che la crescita della popolazione e i cambiamenti climatici possano esercitare una pressione ancora maggiore sulle risorse idriche disponibili. Nonostante le importanti implicazioni che ha l’irrigazione sulla gestione razionale dell’acqua e sulla produzione di cibo, non si ha una conoscenza dettagliata di dove l’irrigazione effettivamente avvenga nel mondo e di quanta acqua venga effettivamente utilizzata per le pratiche irrigue. In questa ricerca sono stati sviluppati approcci per rilevare e mappare le aree dove effettivamente si verifica l’irrigazione e per stimare i volumi irrigui; le metodologie proposte sfruttano l’umidità del suolo rilevata da satellite. In questa ricerca sono stati considerati due casi di studio: il primo si trova nel bacino del fiume Ebro, nel Nord-Est della Spagna, mentre l’altro è il bacino superiore del Tevere, nell’Italia centrale. Diversi prodotti di umidità del suolo da satellite, caratterizzati da diverse risoluzioni spaziali, sono stati valutati al fine di determinare i più performanti nel rilevare segnali di irrigazione e quindi mappare le aree irrigate. Inoltre, sono state eseguite stime quantitative dei volumi di acqua utilizzati per pratiche irrigue. L’attività di rilievo e mappatura dell’irrigazione è stata condotta su entrambe le aree pilota. In quella spagnola, è stata valutata la capacità di rilevare l’irrigazione di diversi prodotti di umidità del suolo. Sono stati considerati i seguenti set di dati: SMAP (Soil Moisture Active Passive) a 1 km e 9 km, SMOS (Soil Moisture and Ocean Salinity) a 1 km, Sentinel-1 a 1 km e ASCAT (Advanced SCATterometer) a 12.5 km. Le versioni a 1 km di SMAP e SMOS sono ottenute tramite disaggregazione eseguita con il metodo DISPATCH (DISaggregation based on Physical And Theoretical scale CHange). La capacità di rilevare l’irrigazione da parte dei prodotti considerati è stata valutata tramite indici derivanti dalla teoria della stabilità temporale e usati in questo studio sotto una nuova prospettiva. Inoltre, sono state prodotte delle mappe delle aree irrigate attraverso l’algoritmo di classificazione K-means. Un’analisi a doppia scala spaziale è stata condotta sulle aree agricole all’interno del bacino superiore del Tevere, in Italia. Nell’ambito dell’analisi alla risoluzione spaziale di 1 km, è stata applicata la stessa procedura già adottata per il caso di studio nel bacino dell’Ebro per valutare la possibilità di rilevare l’irrigazione tramite umidità del suolo da satellite. Sono stati utilizzati i seguenti prodotti: SMAP a 1 km, la versione a 1 km di Sentinel-1 fornita da Copernicus Global Land Service e una versione di Sentinel-1 originariamente prodotta de THEIA alla scala di parcella e aggregata a 1 km. Va sottolineato che i primi due prodotti menzionati sono stati utilizzati anche sull’area pilota in Spagna. Sia in questa analisi che in quella condotta nel bacino dell’Ebro, dati di umidità del suolo superficiale modellati tramite il modello di superficie terrestre SURFEX-ISBA (SURface EXternalisée - Interaction Sol Biosphère Atmosphère) sono stati utilizzati come supporto. Nell’analisi alla scala di parcella, sono stati impiegati i dati di Sentinel-1 prodotti da THEIA e aggregati a 100 m al fine di produrre mappe di aree irrigate ad alta risoluzione tramite l’algoritmo di classificazione K-means. L’attività di quantificazione dell’irrigazione è stata finalizzata solamente per l’area pilota nel bacino dell’Ebro; sono stati condotti due esperimenti: uno utilizzando i dati da SMAP a 1 km e un altro sfruttando i dati da SMOS a 1 km. Entrambi i set di dati sono stati utilizzati per forzare la versione dell’algoritmo SM2RAIN adattata per la stima dell’irrigazione. Una modellazione più realistica dell’evapotraspirazione è stata implementata nell’algoritmo al fine di riprodurre adeguatamente l’evapotraspirazione delle colture secondo il modello FAO (Food and Agriculture Organization). Le analisi condotte sono finalizzate a colmare le lacune esistenti nel campo di ricerca relativo all’irrigazione; i risultati ottenuti sono utili per valutare l’impatto delle pratiche irrigue sul ciclo idrologico.

This dissertation contains three core chapters which share a common theme of natural resource management in Australia and a common analytical technique of Ricardian hedonic price theory applied to agricultural land values. Chapter 1: This chapter presents a Ricardian analysis of the impact of projected climate change on Australian broadacre agricultural land values. Using several years of farmlevel sales data, we estimate the value of agricultural land as a function of climate attributes. We leverage satellite imagery-based land use data to separate our analysis by cropping and grazing land. Making this distinction is particularly important due to choice based sampling (as a consequence of land sale frequency) that would otherwise severely bias our land value estimates. We base our damage estimates on CSIRO climate projections for the 21st century, as used by the Intergovernmental Panel on Climate Change. We find that projected climate change would erode agricultural land values by around 10 per cent by 2050, and nearly 40 per cent by the end of the century; and negatively impact at least 95 per cent of the existing agricultural resource base. This damage is unlikely to occur suddenly. Rather, it would be equivalent to taxing agricultural productivity by about 0.6 per cent per year for the next 85 years. Chapter 2: Australia’s northern area has vast but largely undeveloped land that would be arable if irrigated. We analyse the net economic benefits of allocating northern Australia’s divertible surface water to irrigation, a scheme that would require significant investment in infrastructure for dam and canal construction. We estimate the benefits to northern Australia, using a Ricardian hedonic approach to forecast the economic value of constructing major new irrigation schemes that would be capitalised into agricultural land values. We use publicly available information from existing and potential Australian irrigation schemes to define the cost of constructing large water storages and distribution infrastructure, as well as on-farm irrigation infrastructure. We find that the costs of turning northern Australia into an irrigated food bowl are likely to exceed even the most optimistic benefits that would be capitalised into land prices by a multiple of between 1.1 and 3.2. Chapter 3: This chapter explores the damage wrought on broadacre agricultural property values by dryland salinity in the south-west agricultural region of Western Australia – one of Australia’s most productive wheat growing areas. We use a Ricardian hedonic approach based on 20 years of farm sales data to estimate salinity damages. We find that the damage caused by salinity in the south-west varies from approximately 20 per cent for land that is slightly affected by salinity to as much as 87 per cent for land that is extremely saline. Using these estimates, we project that the upside from eliminating existing salinity on 5.3 million hectares of currently impacted land would be worth approximately $2.6 billion. Conversely, if left unchecked, we find that an additional 3.75 million hectares of land worth approximately $5.85 billion is likely to become saline at some point in the future.

碩士
國立中央大學
土木工程研究所
97
This research investigated the influence of irrigation water requirement with the change of irrigation operation including channel supply and wire supply. Taoyuan Channel #2 Feeder was selected as study area. The irrigation resource included Shihmen reservoir, Nankan stream and Puxin stream. The agriculture irrigation system model was established by Vinsim model and irrigation water supply data in 2008 was applied. The simulation was divided into five cases. In case 1 to 4, the water supply from the reservoir was reduced in different patterns, up to 0 mm, while in Case 5 the supply from the river weir was changed. Case1 to Case 4 was to investigate the adjusted irrigation water volume which depended on operation methods. Case 5 was to simulate when half of water was supplement by weir gradually. The result showed that the total irrigation water volume decreased to 266mm and 366mm, which depended on paddy storage depth. The rice paddy with weir water supply only could maintain corps survival. The water supply operation which based on the height of ridge could save 200mm of irrigation water. This approach shows high feasibility on operation. Case5 simulation result indicated that the corps still maintained survival in downstream irrigation area. This study applied Vinsim model to evaluate the impact of irrigation water supply from two sources on the number 2 Feeder rice paddy in Tao-Yuan county, Taiwan. The rice paddy was divided into three zones, A, B and C respectively. These water supply sources originated from the Shimen reservoir via the number 2 Feeder canal and a river weir. Rainfall, evaporation and irrigation supply data from these two sources for 2008 were used to simulate in this study. The water supply from the sources were changed in to 5 cases, The results showed that for case 1 and 2, two zones A, B of rice paddy can satisfy crop growth demand, but for cases 3 and 4, zone B can not satisfy about 10 days of August. In case 5, the water supply from the river weir was reduced 50%. From the application of model it was found out that only these areas d1, d2, d3 and Shalun of Zone C satisfy crop growth demand.

碩士
國立臺灣大學
生物環境系統工程學研究所
100
To efficiently manage the limited water supply resources is an important issue in Taiwan. The planning and management of agricultural water use is very important due to its large share (more than 70%) of the total water consumption. There are a lot of spatially related information, such as soil, crop weather and canal system, involved in the agricultural water management practices. Geographic Information System (GIS) was used to manage these spatial data and implement the Spatial Decision Support System (SDSS) for effectively manage the agricultural water use. The traditional GIS based SDSS is less flexible and portable and much difficult to implement or modify in different irrigation command areas or to adapt to the environmental change due to factors like global climate change. A non-GIS Excel-based DSS is proposed in this study to make the traditional SDSS more efficient, flexible and portable. Although the proposed system is not based on GIS, the necessary spatial characteristics for effective planning and management decisions are preserved. The system also provide user interface which makes scenario setup and simulation easy, therefore user can obtain necessary information for decision and realize the irrigation demand variation mechanism through changing the parameter of irrigation demand estimation and scenario situation. This proposed system is more portable and may be transplanted to different irrigation command area with less efforts. The command area of Taoyuan and Shimen irrigation associations and the Pai-Ho reservoir irrigation command area used as pilot study areas. The results show that this proposed system concept can provide fast and convenient regional irrigation water demand estimation to each Irrigation Associations in Taiwan. The system may also be extended to include the allocation model for supply and demand management, economic oriented analysis for better efficiency in planning and management of the limited water resources.

AbstractIn the potassium (K) cycle, inputs encompass all K sources that move into a given volume of soil. These inputs may include atmospheric deposition, irrigation water, runoff, erosion, as well as seeds, cuttings, and transplants. Accounting for all inputs is seldom routinely done on the farm. Many K inputs have variable concentrations, making estimations difficult. Estimates for added K are provided in some planning documents and can be used where testing of on-farm inputs is not feasible, although testing is preferred. Standard commercial fertilizers have known concentrations of K and are concentrated enough to be economical to transport long distances. The global reserves for their production have an estimated lifetime of thousands of years. This chapter emphasizes considerations for using various commercial fertilizer sources.

AbstractThis study developed a marginal abatement cost curve (MACC) to identify a mix of least-cost investment options with the highest potential for hunger reduction, hunger here defined by the undernourishment concept of the Food and Agriculture Organization (FAO). Twenty-two different interventions are considered for reducing undernourishment relying on information drawn from best available evidence-based literature, including model- and large-scale intervention studies. Ending hunger by 2030 would require annual investments of about US$ 39 to 50 billion until 2030 to lift about 840 to 909 million people out of hunger, which is the 2020 estimate of hunger projection in 2030, also considering the effects of COVID-19. Investing in agricultural R&D, agricultural extension services, information and communication technologies (ICT) – agricultural information systems, small-scale irrigation expansion in Africa and female literacy improvement are low cost options that have a relatively large hunger reduction potential. To achieve the goal of ending hunger by 2030, not only is it urgent not to lose any more time, but also to optimally phase investments. Investments that have more long-term impacts should be frontloaded in the decade in order to reap their benefits soon before 2030. A balanced approach is needed to reach the hungry soon – including those adversely affected by COVID-19 with social protection and nutrition programs.

The chapter begins with looking at ways humans have dealt with drought—praying for rain, hiring a rainmaker, or hoping for the best. After World War II, the widespread availability of rural electrification, the deep turbine pump, and center pivot irrigation gave people the option of large-scale use of groundwater. This chapter provides an overview of how groundwater development has radically improved water and food security. The discussion then moves to the growing problems that have resulted from groundwater overuse in places such as the High Plains (Ogallala) Aquifer and the North China Plain. Recently, the GRACE (Gravity Recovery and Climate Experiment) satellites, which can provide precise estimates of changes in groundwater storage over very large areas, have helped draw attention to groundwater depletion around the world.

This article develops new estimates of historical agricultural productivity growth in Jordan. It investigates how public policies such as agricultural research, investment in irrigation capital, and water pricing have contributed to agricultural productivity growth. The Food and Agriculture Organization (FAO) annual time series from 1961 to 2011 of all crops and livestock productions are the primary source for agricultural outputs and inputs used to construct the Törnqvist Index for the case of Jordan. The log-linear form of regression equation was used to examine the relationship between Total Factor Productivity (TFP) growth and different factors affecting TFP growth. The results showed that human capital has positive and direct significant impact on TFP implying that people with longer life expectancy has a significant impact on TFP growth. This article concludes that despite some recent improvement, agricultural productivity growth in Jordan continues to lag behind just about every other region of the world.

Many of the agricultural plots within Trinidad and Tobago remain in a state of dormancy due to a critical lack of infrastructure needed for their development. This has contributed to the increasing food import bill which was some TT$5.6 billion over the last couple of years. This overall crop irrigation project aims at assisting the farmers in setting up a proper infrastructure that will utilize natural resources. The lack of pipe water will be substituted by rainwater capture, storage and distribution via drip irrigation. The lack of power for water distribution by irrigation will be obtained by the use of solar power for the pumps. The project will be done in phases. This phase involved at creating a smart estimator to determine the water requirement and the planting land area for the 2-acre plot when the number of plants, type of plants, and the month in which the farmer chooses to start planting are chosen. It will estimate the water storage volume required for the various crops chosen based on the rainfall patterns, crop cycle and the crop water requirement. These output estimates will be based on the land area input, estimated water storage size, estimated tool shed size and produce storage area, and the type or types of crops chosen to farm by the farmer for the plot. The input parameters in the estimator can then be varied by the farmer, to help find an estimated or optimum balance of the number and type of crops, the planting land area, and the water captured and stored, based on the rainfall patterns and the unused land area. The outputs required can be similarly obtained through the use of existing models and software packages, but the tools are not ‘Farmer User Friendly and readily available’.

Maui Island in the State of Hawaii faces land use and freshwater allocation challenges associated with a growing population and a changing economic base as plantation agriculture has declined. Debate about whether water should be restored to environmental flows, allocated to new urban development for residents and tourists, or be used to irrigate food or fuel crops has highlighted Maui’s opportunity to make integrated resource decisions that consider land, water, and energy in particular. One major potential water demand on Maui is for irrigation for biofuels crops, such as sugarcane for ethanol. While Maui’s energy system is currently low in water intensity, using irrigated biofuels could increase the need for local water investment in energy systems. This paper aims to characterize surface water supply on Maui in order to draw conclusions about supply adequacy for biofuel irrigation. Narrow-scope empirical equations linking streamflow and precipitation tend to produce more accurate estimates for individual streams: for example, equations based only on northeast Maui streams tend to predict northeast Maui stream flows better than equations based on all of Maui’s streams. However, specific equations do not exist for most regions of Maui. This paper finds that general and specific empirical equations for northeast Maui predict nearly identical aggregate streamflows. Irrigation ditch flow comprises aggregate streamflow from a given region, so it is likely that existing, general equations can predict irrigation ditch flows with acceptable accuracy.

What are the returns to smallholders when they grow commercial crops for sale in rural Africa? The gross value of production per hectare is sometimes reported, with some recent estimates ranging from as much as US$10,000/ha for irrigated vegetables in Zimbabwe to as little as US$250 for sunflower grown on semi-arid land without irrigation in central Tanzania. Gross value, however, takes no account of the costs farmers incur in growing their crops. In this paper, we use gross margin (GM) analysis to take account of those costs and give a truer estimate of the returns to farmers.

The need to enhance food security while reducing poverty along with the growing threat imposed by climate change clearly reveal that it is imperative to accelerate agricultural productivity growth. This paper estimates micro-level production models to identify the major factors that have contributed to productivity growth in El Salvador, including irrigation, purchased inputs, mechanization, technical assistance, and farm size, among others. The econometric framework adopted in this investigation is grounded on recent panel data stochastic production frontier methodologies. The results obtained from the estimation of these models are used to calculate Total Factor Productivity (TFP) change and to decompose such change into different factors, including technological progress, technical efficiency (TE), and economies of scale. The findings imply that efforts are needed to improve productivity in both technological progress and technical efficiency where the latter is a measurement of managerial performance. This in turn indicates that resources should be devoted to promoting the adoption and diffusion of improved technologies while enhancing managerial capabilities through agricultural extension.

Sodium affected soils, along with salt-affected soils, are distributed widely in irrigated areas of the arid and semi-arid region of the world. Some of these soils can and must be reclaimed to meet the increasing demand for food, and existing irrigated lands must be managed to reduce salinization and alkalization associated with deteriorating irrigation water quality. This project was conducted for examining ways to reduce the use of chemical amendments and large quantities of leaching water for reclaiming sodic soils or for preventing soil sodification, We hypothesized that sodicity of calcareous soils irrigated with moderately sodic irrigation water can be controlled by maximizing dissolution of soil CaCO3. The work performed in Israel has shown that dissolution of CaCO3 can be enhanced by elevating the CO2 partial pressure in soils, and by increasing pore water velocity. The concentration of Ca in pore water was at an order of 1.5 mmolc L-1 at a CO2 partial pressure of 5 kPa, which is sufficient to maintain SAR below 4 at salinity of irrigation water of 0.5 dS m-1 or less. Incorporation of crop residue at a flesh weight of 100 Mg ha-1 reduced the exchangeable Na percentage from 19 to 5%, while it remained 14% without crop residue application These findings indicate a possibility of preventing soil sodification with appropriate crop rotation and residue management without chemical amendments, provided that soils remain permeable. In the case of highly sodic soils, dissolution of CaCO3 alone is usually insufficient to maintain soil permeability during initial leaching. We examined the effect of salinity and sodicity on water infiltration, then developed a way to estimate the amendments required on the basis of water infiltration and drainage characteristics, rather than the traditional idea of reducing the exchangeable Na percentage to a pre-fixed value. Initial indications from soil column and lysimeter study are that the proposed method provides realistic estimates of amendment requirements. We further hypothesized that cultivation of salt-tolerant plants with water of elevated salinity can enhance reclamation of severely Na-affected soils primarily through improved water infiltration and increased dissolution of CaCO3 through respiration. An outdoor lysimeter experiment using two saline sodic Entisols sodded with saltgrass for two seasons did not necessarily support this hypothesis. While there was an evidence of increased removal of the exchangeable Na originally present in the soils, the final salinity and sodicity measured were lowest without sod, and highest when sodded. High transpiration rates, coupled with low permeability and/or inadequate leaching seemed to have offset the potential benefits of increased CaCO3 dissolution and subsequent removal of exchangeable Na. Although vegetative means of reclaiming sodic soils had been reported to be effective in sandy soils with sufficient permeability, additional study is needed for its use in saline sodic soils under the high evaporative demand. The use of cool season grass after initial salt leaching with CaCl2 should be explored. Results obtained from this project have several potential applications, which include the use of crop residues for maintaining sodium balance, the use of CaCl2 for initial leaching of poorly permeable clayey sodic soils, and appraisal of sodicity effects, and appropriate rates and types of amendments required for reclamation

Original objectives and revisions The original objectives of this research, as stated in the approved proposal were: 1. To establish guidelines for the use of turbulent transport techniques as accurate and reliable tool for continuous measurements of whole canopy ET and other scalar fluxes (e.g. heat and CO2) in large agricultural structures. 2. To conduct a detailed experimental study of flow patterns and turbulence characteristics in agricultural structures. 3. To derive theoretical models of air flow and scalar fluxes in agricultural structures that can guide the interpretation of TT measurements for a wide range of conditions. All the objectives have been successfully addressed within the project. The only modification was that the study focused on screenhouses only, while it was originally planned to study large greenhouses as well. This was decided due to the large amount of field and theoretical work required to meet the objectives within screenhouses. Background In agricultural structures such as screenhouses and greenhouses, evapotranspiration (ET) is currently measured using lysimeters or sap flow gauges. These measurements provide ET estimates at the single-plant scale that must then be extrapolated, often statistically or empirically, to the whole canopy for irrigation scheduling purposes. On the other hand, turbulent transport techniques, like the eddy covariance, have become the standard for measuring whole canopy evapotranspiration in the open, but their applicability to agricultural structures has not yet been established. The subject of this project is the application of turbulent transport techniques to estimate ET for irrigation scheduling within large agricultural structures. Major conclusions and achievements The major conclusions of this project are: (i) the eddy covariance technique is suitable for reliable measurements of scalar fluxes (e.g., evapotranspiration, sensible heat, CO2) in most types of large screenhouses under all climatic conditions tested. All studies resulted with fair energy balance closures; (ii) comparison between measurements and theory show that the model is capable in reliably predicting the turbulent flow characteristics and surface fluxes within screenhouses; (iii) flow characteristics within the screenhouse, like flux-variance similarity and turbulence intensity were valid for the application of the eddy covariance technique in screenhouses of relatively dilute screens used for moderate shading and wind breaking. In more dense screens, usually used for insect exclusions, development of turbulent conditions was marginal; (iv) installation of the sensors requires that the system’s footprint will be within the limits of the screenhouse under study, as is the case in the open. A footprint model available in the literature was found to be reliable in assessing the footprint under screenhouse conditions. Implications, both scientific and agricultural The study established for the first time, both experimentally and theoretically, the use of the eddy covariance technique for flux measurements within agricultural screenhouses. Such measurements, along with reliable theoretical models, will enable more accurate assessments of crop water use which may lead to improved crop water management and increased water use efficiency of screenhouse crops.

This study considers existing off-grid initiatives that are being implemented in support of more rapid electrification in sub-Saharan Africa. After first reviewing the successes and obstacles of commonly implemented off-grid solutions, we suggest groundwater irrigation powered via off-grid solar (OGS) systems as a productivity-focused electrification solution that could be valuable to off-grid development initiatives moving forward. This solution encourages the establishment of OGS pumping infrastructure in unelectrified areas in proximity to nonirrigated agriculture that have promising and sustainable groundwater abstraction potential. Using open-access spatial data to estimate the alignment of these resources is an important first step in determining potential study sites for on-the-ground research and pilot projects. This study focuses on applying the above approach to Ethiopia to produce a spatial layer representing areas that are recommended for further assessment of their OGS groundwater irrigation viability. We follow the spatial analysis with a projection of potential gains from investment in OGS groundwater pumping systems under different scenarios to highlight the solution’s viability with regional context. This assessment provides an initial methodology for identifying, examining, and expanding upon potential markets where OGS irrigation can become an economically viable solution.

Original objectives and revisions The original objectives as stated in the approved proposal were: (1) To establish guidelines for the use of micrometeorological techniques as accurate, reliable and low-cost tools for continuous monitoring of whole canopy ET of common crops grown in large agricultural structures. (2) To adapt existing methods for protected cultivation environments. (3) To combine previously derived theoretical models of air flow and scalar fluxes in large agricultural structures (an outcome of our previous BARD project) with ET data derived from application of turbulent transport techniques for different crops and structure types. All the objectives have been successfully addressed. The study was focused on both screenhouses and naturally ventilated greenhouses, and all proposed methods were examined. Background to the topic Our previous BARD project established that the eddy covariance (EC) technique is suitable for whole canopy evapotranspiration measurements in large agricultural screenhouses. Nevertheless, the eddy covariance technique remains difficult to apply in the farm due to costs, operational complexity, and post-processing of data – thereby inviting alternative techniques to be developed. The subject of this project was: 1) the evaluation of four turbulent transport (TT) techniques, namely, Surface Renewal (SR), Flux-Variance (FV), Half-order Time Derivative (HTD) and Bowen Ratio (BR), whose instrumentation needs and operational demands are not as elaborate as the EC, to estimate evapotranspiration within large agricultural structures; and 2) the development of mathematical models able to predict water savings and account for the external environmental conditions, physiological properties of the plant, and structure properties as well as to evaluate the necessary micrometeorological conditions for utilizing the above turbulent transfer methods in such protected environments. Major conclusions and achievements The major conclusions are: (i) the SR and FV techniques were suitable for reliable estimates of ET in shading and insect-proof screenhouses; (ii) The BR technique was reliable in shading screenhouses; (iii) HTD provided reasonable results in the shading and insect proof screenhouses; (iv) Quality control analysis of the EC method showed that conditions in the shading and insect proof screenhouses were reasonable for flux measurements. However, in the plastic covered greenhouse energy balance closure was poor. Therefore, the alternative methods could not be analyzed in the greenhouse; (v) A multi-layered flux footprint model was developed for a ‘generic’ crop canopy situated within a protected environment such as a large screenhouse. The new model accounts for the vertically distributed sources and sinks within the canopy volume as well as for modifications introduced by the screen on the flow field and microenvironment. The effect of the screen on fetch as a function of its relative height above the canopy is then studied for the first time and compared to the case where the screen is absent. The model calculations agreed with field experiments based on EC measurements from two screenhouse experiments. Implications, both scientific and agricultural The study established for the first time, both experimentally and theoretically, the use of four simple TT techniques for ET estimates within large agricultural screenhouses. Such measurements, along with reliable theoretical models, will enable the future development of lowcost ET monitoring system which will be attainable for day-to-day use by growers in improving irrigation management.

In this paper, we estimate a stochastic production function for Bolivia, Ecuador, Colombia, and Peru to investigate whether road infrastructure affects farm technical inefficiency. We use agricultural censuses of Colombia and Bolivia in 2013 and 2014, respectively; national agricultural surveys in 2017 of both Ecuador and Peru; and data on the road network and travel time to the nearest town with 50,000 inhabitants or more. Our main findings are that irrigation increases the value of production and road network decreases farm technical inefficiency, that is, road density (travel time) increases (decreases) farm technical efficiency.