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1
Guinan, Patrick E. "Seasonally adjusted index for projecting agricultural drought /". free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p3164510.
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Quiring, Steven M. "Developing a real-time agricultural drought monitoring system for Delaware". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 2.86 Mb , 207 p, 2005. http://wwwlib.umi.com/dissertations/fullcit/3181867.
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Hassan, Gana Abdullahi. "Drought and drought mitigation in Yobe State, Nigeria". Thesis, University of Wolverhampton, 2018. http://hdl.handle.net/2436/621793.
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Drought is regarded as a natural phenomenon and its impacts accumulate slowly over a long period. It is considered to be insufficient precipitation that leads to water scarcity, as triggered by meteorological parameters, such as temperature, precipitation and humidity. However, drought mitigation has mostly been reactive, but this has been challenged by extreme events globally. Many countries and regions around the world have made efforts in mitigating drought impacts, including Nigeria. This research produced frameworks for drought amelioration and management as a planning tool for Yobe State, Nigeria. Mixed methods were employed to investigate the effects of drought; 1,040 questionnaires were administered to farmers in three regions of Yobe State (South, North and East). Some 721 were returned, representing a 69.3% return rate. Drought is pronounced in the State and has been recent over the years; it has also affected many people, with losses of ~70-80% of their harvests and livestock. Drought coping strategies have also caused environmental degradation in Yobe State. Farmers over-harvest their farms, practise deforestation and over-exploit wild animals. Several efforts to mitigate the impacts of drought by the Nigerian Government have failed, thus this research adopts a bottom-top approach to mitigate drought impacts in Yobe State. Focus Group Discussions (FGD) were also conducted at government and community levels to gather farmers' and government officials' opinions on their drought experience and suggestions for mitigation measures. Farmers believed that rainfall is their main problem and officials pointed that there are no proper drought mitigation plans in Yobe State. Four validated drought mitigation and management frameworks were developed for Yobe State. The frameworks were evaluated pre-use through respondent validation. State officials and farmers believed that these frameworks will reduce the impacts of drought in Yobe State. The frameworks include social, economic, environmental impact mitigation and an Integrated Drought Mitigation and Management Framework. The proposed frameworks were designed and have advocates a paradigm shift, using both proactive and reactive measures. A new drought definition was proposed based on the findings of the study. The definition states that drought is the shortage of rainfall or water that affects people's livelihood and the environment both directly and indirectly.
4
Bellamy, John Thomas. "Drought frequency and risk analysis in the Upper Green River Basin, Wyoming". Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1798480881&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Sprinkle, Jim. "Supplementation During Drought". College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 1998. http://hdl.handle.net/10150/144719.
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6 pp.Breeding failure is the most important adverse consequence to the cow herd during drought. This is due to reduced forage quality and availability, resulting in nutritional stress. This publication provides information on how to supplement cattle to meet its nutrient requirements during drought.
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Abraham, Joseph. "Assessing drought vulnerability". Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/196047.
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This dissertation makes valuable contributions to hazard and disaster vulnerability assessment theory and methodology. Appendix A presents results of a national survey of state drought planning processes that examined and evaluated how state processes were assessing drought impacts and vulnerabilities, and how assessments were used to mitigate risk. While impact and vulnerability assessments have been useful for reactive, short-term mitigation, most were found to have not been used to develop pro-active and/or committed, long-term mitigation programs. To be useful for developing long-term planning and mitigation, assessments must involve more social scientists, a greater emphasis on second-, third-, etc., order impacts, and examining how systems are sensitive to drought exposure, and studying adaptive capacity. Appendix B adapts a political economy/human ecology and political ecology research framework and examines how regional historical, institutional and regional development patterns in central Arizona have contributed to the production of local drought vulnerability in rural Arizona during the 20th century. The study evaluates the applicability of a research framework developed in Third World settings, and resulted in valuable insights for developing state and county policy in Arizona to mitigate social, economic, and political-institutional drivers of drought vulnerability. Appendix C compliments the assessment in Appendix B by examining local drivers of drought vulnerability and conducting a comparative drought vulnerability analysis in two rural communities in northern Gila County, Arizona. The assessment found local differences in community water system vulnerabilities were driven by differences in capacity to adapt to climate variability and population growth. Differences in adaptive capacity, in turn, were driven by differences in local management, institutional factors, and economic incentives of private and public water systems. Together, the three appendices contribute practical and theoretical contributions for assessments conducted by state and local governments, non-governmental organizations, and academic research units that seek to assess and ultimately mitigate hazard and disaster vulnerability.
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Sprinkle, Jim E. "Supplementation During Drought". College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2011. http://hdl.handle.net/10150/239551.
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Singh, Kamal. "Drought, relief and rural communities : special report no. 9". Association for Rural Advancement (AFRA), 1993. http://hdl.handle.net/10962/68651.
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The Association for Rural Advancement (AFRA) has run a Drought Project since October 1992. The project's primary focus was to monitor drought conditions in the AFRA's operational area and to assist communities to access relief through providing them with relevant information and helping them to submit proposals to relief agencies. In attempting to do this, it became clear that the effects of drought on rural black communities was not a well understood phenomenon. We also found that relief strategies were informed more by economic, agricultural and meteorological criteria than social ones. This Special Report aims to contribute to the development of a more appropriate drought management strategy, especially with regard to rural communities. In attempting to make this contribution, the Report examines the factors involved in redefining drought and drought relief perspectives in relation to rural communities. However, the range of factors involved and the scarcity of useful information on them, dictate that this is merely an introduction. The complexities and implications arising from the introduction of these factors into drought management in South Africa should be explored on an on-going basis. Because of the scarcity of relevant information about the effects of drought on black rural communities in South Africa, this Report has relied on AFRA's limited monitoring of such communities. Some information was also gathered through Participatory Rural Appraisal (PRA) methods. There were also difficulties in getting information about relief schemes and their operations as most relief agencies were reluctant to release this information. As a result, almost all the relief related information in this Special Report was obtained from publications and reports of the National Consultative Forum on Drought.
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Lohani, Vinod K. "Characterization of palmer drought index as a precursor for drought mitigation". Diss., Virginia Tech, 1995. http://hdl.handle.net/10919/39044.
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Coping with droughts involves two phases. In the first phase drought susceptibility of a region should be assessed for developing proper additional sources of supply which will be exploited during the course of a drought. The second phase focuses on the issuance of drought warnings and exercising mitigation measures during a drought . These kinds of information are extremely valuable to decision making authorities.
In this dissertation three broad schemes i) time series modeling, ii) Markov chain analysis, and iii) dynamical systems approach are put forward for computing the drought parameters necessary for understanding the scope of the drought. These parameters include drought occurrence probabilities, duration of various drought severity classes which describe a region's drought susceptibility, and first times of arrival for non drought classes which signify times of relief for a drought-affected region. These schemes also predict drought based on given current conditions.
In the time series analysis two classes of models; the fixed parameter and the time varying models are formulated. To overcome the bimodal behavior of the Pallner Drought Severity Index (PDSI), primarily due to the backtracking scheme to reset the temporary index values as the PDSI values, the models are fitted to the Z index in addition to the PDSI for the forecasting of the PDSI.Ph. D.
10
Chbouki, Nabil. "Spatio-temporal characteristics of drought as inferred from tree-ring data in Morocco". Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185851.
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Long-term tree-ring series of Cedrus atlantica have been utilized to reconstruct and characterize past drought occurrences in Morocco. Based on the close relationship between tree growth and rainfall variations, the best tree-ring indicator of drought has been found to be, x₀ = μ -.75σ, with μ and σ the mean and standard deviation of the tree-ring series. In Morocco, drought is a short event lasting 1.7 years on average with 84% of the events lasting less than 2 years. The average maximum duration exceeds 4 years. It is associated with a 40% deficit about normal moisture availability which can add up to more than 125% when the anomalies persist. The average empirical recurrence interval of drought is 8 years. Long-term persistence has been characterized by the Hurst coefficient. Over the domain of study, the mean Hurst coefficient is .765. The tree-ring series show a periodic behavior with two major peaks at 22 and 66 years. Drought characteristics have been extended from the tree-ring sites to other regions such as the agricultural plains using geostatistical methods. The drought prone areas are located in central Morocco, including the Sais, the Gharb and central Middle Atlas, which experience longer, more severe and more persistent droughts. The northern latitudes experience milder and shorter drought events. The cost for spatial extension of the results was greater kriging errors which make the estimates less reliable. However, cokriging significantly improved the reliability and the quality of the estimates. A regionalization, using cluster analysis, was found to follow the natural climatic and orographic zones of north central Morocco. The tree-ring data were used to reconstruct spatial patterns of moisture anomalies for the period 1845-1974. Three atmospheric factors appear to be important: (1) the relative strength and position of the Azores High, (2) the importance and location of the local cyclogenesis centers, (3) the importance of the northeastern perturbations coming from the Mediterranean sea. The periods 1860-1890, 1925-1950 and the 1970's are associated with dry anomalies while the periods 1900-1920 and 1950-1970 are associated with wet anomalies. They exhibit a rhythmic succession with a 20-year periodicity.
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Batlang, Utlwang. "Identification of Drought-Responsive Genes and Validation for Drought Resistance in Rice". Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/26020.
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Drought stress was studied in rice (Oryza sativa) and maize (Zea mays) to identify drought-responsive genes and associated biological processes. One experiment with rice examined drought responses in vegetative and reproductive tissues and identified drought-responsive genes in each tissue type. The results showed that brief periods of acute drought stress at or near anthesis reduced photosynthetic efficiency and ultimately lowered grain yield. Yield was reduced as a result both of fewer spikelets developed and of lower spikelet fertility. Affymetrix arrays were used to analyze global gene expression in the transcriptomes of rice vegetative and reproductive tissue. Comparative analysis of the expressed genes indicated that the vegetative and reproductive tissues responded differently to drought stress.
An experiment was conducted with maize, using GS-FLX pyrosequencing to identify differentially expressed genes in vegetative and reproductive tissues; and these results were compared with those from the just-described rice transcriptome. Some of the drought-responsive genes in the maize reproductive tissue were validated by quantitative real time polymerase chain reaction (qRT-PCR). The differentially expressed genes common to both maize and rice were further analyzed by gene ontology analysis to reveal core biological processes involved in drought responses. In both species, drought caused a transition from protein synthesis to degradation, and photosynthesis was one of the most severely affected metabolic pathways.
In a validating experiment, a drought-responsive transcription factor found in rice and dubbed HIGHER YIELD RICE (HYR) was constitutively expressed in rice, and the transgenic HYR plants were studied. Under well-watered conditions, the HYR plants developed higher rates
of photosynthesis, greater levels of soluble sugars (glucose, fructose, and sucrose), more biomass, and higher yield. They also exhibited a drought-resistant phenotype, with higher water use efficiency, photosynthesis, and relative leaf water content under drought stress. Taken together, these studies demonstrate the potential value of newer technologies for identifying genes that might impart drought resistance and for using such genes to make crops more productive either in the presence or in the absence of drought stressPh. D.
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Shrestha, Alen. "ANALYZING THE PAST AND FUTURE DROUGHT SITUATIONS USING HIGH RESOLUTION DROUGHT INDEX". OpenSIUC, 2020. https://opensiuc.lib.siu.edu/theses/2757.
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Regional assessments of droughts are limited and meticulous assessment of droughts over larger spatial scales are often not substantial. Understanding drought variability on a regional scale is crucial for enhancing resiliency and adaptive ability of water supply and distribution systems. Moreover, it can be essential for appraising the dynamics and predictability of droughts based on regional climate across various spatial and temporal scales. The drought analysis of the past was carried out with the development of a high-resolution dataset (1km×1km) for three drought-prone regions of India between 1950 and 2016. In the study the monthly values of self-calibrating Palmer Drought Severity Index (scPDSI), incorporating Penman–Monteith (PM) approximation, which is physically based on potential evapotranspiration. Climate data were statistically downscaled using the delta downscaling method and was formulated to form a timeline for characterizing major drought events that occurred in the past. The downscaled climate data were validated with the station observations. Major severe drought events that occurred between 1950 and 2016 were identified and studied with greater emphasis to the drought situation in smaller spatial extent such as districts, villages or localities. A timeline of drought events within the period of study was also prepared to have an understanding of the severity of drought in all three regions.Likewise, the future drought durations are projected for droughts of different levels of severity and assessed in the same regions of India. Coupled Model Intercomparison Project Phase 6 (CMIP6) simulated precipitation and climate data were used for near‐future (2015–2044) for different shared socio-economic pathways (SSPs). scPDSI, was used again based on its fairness in identifying drought conditions which accounts for the temperature as well. Gridded rainfall and temperature data of spatial resolution of 1km were used to bias correct the multi-model ensemble (MME) mean of 7 Global Climatic Models (GCMs) from CMIP6 project. Equidistant quantile-based mapping was adopted to remove the bias in the rainfall and temperature data and were corrected at the monthly scale. The downscaled climate data exhibited good statistical agreement with station data with correlation coefficient (R) ranging from 0.83 to 0.93 for both precipitation and temperature. Drought analysis indicated several major incidences over the analysis time period considered in this work, which truly adheres to the droughts recorded in qualitative reports of meteorological institutions in those regions. The drought study of the past helped to understand the situation in local levels and understand the necessities that can be opted for the future by proper management of water resources. While the outcome of the future prediction of drought duration suggests multiple severe to extreme drought events in all three study areas of appreciable durations mostly during the mid-2030s under the SSP2-4.5 scenario. The severe drought durations under the SSP2-4.5 scenario were found to be ranging around 25 to 30 months in 30 years period of the near future. The high-resolution drought index proved to be key to assess the drought situation for both the past and the future in three different drought-prone regions of India.
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Yang, Wen. "Drought Analysis under Climate Change by Application of Drought Indices and Copulas". PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/716.
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Drought is a recurrent extreme climate event with tremendous hazard for every specter of natural environment and human lives. Drought analysis usually involves characterizing drought severity, duration and intensity. Similar to most of the hydrological problems, such characteristic variables are usually not independent. Copula, as a model of multivariate distribution, widely used in finance, actuarial analysis, has won increasingly popularity in hydrological study. Here, the study has two major focuses: (1) fit drought characteristics from Streamflow Drought Index (SDI) or Standardized Runoff Index (SRI) to appropriate copulas, then using fitted copulas to estimate conditional drought severity distribution and joint return periods for both historical time period 1920-2009 and future time period 2020-2090. SDI is calculated based on long term observed streamflow while SRI is based on simulated future runoff. Parameters estimation of marginal distribution and copulas are provided, with goodness fit measures as well; (2) investigate the effects of climate change on the frequency and severity of droughts. In order to quantify the impact, three drought indices have been proposed for this study to characterize the drought duration, severity and intensity changes under the climate change in Upper Klamath River Basin. Since drought can be defined as different types, such as meteorological drought, agricultural drought, hydrological drought and social economical drought, this study chooses Standardized Precipitation Index (SPI), Palmer Drought Severity Index (PDSI) and Surface Water Supply Index (SWSI) to estimate the meteorological, agricultural and hydrological drought, respectively. Climate change effects come from three sources: the inherent reason, the human activity and the GCMs uncertainties. Therefore, the results show the long term drought condition by calculating yearly drought indices, and compared in three ways: First, compare drought characteristics of future time periods with base period; second, show the uncertainties of three greenhouse gas emission scenarios; third, present the uncertainties of six General Circulation Models (GCMs).
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Gaffney, Benjamin (Benjamin Michael) 1970, i Manal 1976 Hatem-Moussallem. "Cyprus drought water bank". Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/67164.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999.Includes bibliographical references (p. 119-123).
Water banking is a proven water management strategy that facilitates the voluntary temporary reallocation of water from willing sellers to willing buyers. In exchange for compensation, farmers (sellers) may choose to allow their irrigation water to be reallocated to cities, towns, industries, and tourist hotels (buyers) that are in need. We have studied the application of water banking concepts to the water management of the island of Cyprus. The Republic of Cyprus is currently facing significant water scarcity problems. Water banking is a new idea in the area. We propose that an emergency drought water bank encourages farmers to become part of the solution to the water problems on the island. The Cypriot government is currently turning to desalination of seawater to meet its water supply needs. This process offers a reliable but very expensive source of water. The water from the most recent desalination contract will cost the government more than CY£ 61 million in total over the next ten years, assuming that the price of oil does not rise. In order to minimize the cost of water resources development, we propose forward-thinking policies such as water banking to reduce the need for additional desalination plants. This thesis details the goals, structure, and operational strategy for a water bank in Cyprus. We recommend that the Government seriously consider the immediate application of water banking. A small-scale pilot project in a single irrigation district would allow the concept to be validated in the field. Water banking holds great promise as a means of helping to provide Cyprus with the water it needs for continued growth and prosperity.
by Benjamin Gaffney & Manal Hatem-Moussallem.
M.Eng.
15
Kaniewski, Connie. "Understanding Flash Drought Spatial Extent, Duration, and Meteorological Drivers". OpenSIUC, 2021. https://opensiuc.lib.siu.edu/theses/2876.
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Drought is conventionally known as a slow-developing natural hazard. In recent years, a subset of drought events characterized by rapid onset has been identified and deemed “flash” droughts. These flash droughts can result in rapid soil drying and rapid vegetation degradation making them damaging to agriculture and the economy, so it is essential to develop reliable early warning systems for flash drought events. This study aims to compare the climatology between flash and non-flash droughts across the Contiguous United States (CONUS) and regionally to identify key differences in the drought types to improve early warning. Flash drought is defined as a two- or more category degradation in the U.S. Drought Monitor (USDM) in 4 weeks or less. Potential evapotranspiration (PET), vapor pressure deficit (VPD), maximum temperature (Tmax), and minimum temperature (Tmin) from the Gridded Surface Meteorological Dataset (gridMET) were also analyzed for flash and non-flash drought. It was found that using this definition of flash drought, flash droughts are up to 70% more likely to occur than non-flash droughts over all of the CONUS except the west coast. The South and Southwest regions are more likely to have more frequent and longer flash drought events than the Northwest and Plains regions. This study concludes that PET and VPD are the most reliable variables for differentiating between a flash and non-flash drought event. Furthermore, flash drought is most prevalent and will be the most difficult to predict in the South and Southwest regions and easier to predict in the Northwest and Plains. Also, using a flash drought definition of a drop in two or more categories in the USDM may be too lenient. A narrower flash drought definition, such as a drop in two categories over a two- or three-week period, may be more reflective of the more damaging nature of flash drought events.
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Kleopa, Xenia A. "Optimal reservoir operation for drought management". Ohio : Ohio University, 1990. http://www.ohiolink.edu/etd/view.cgi?ohiou1183650664.
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Mullen, Caroline. "An investigation into the effects of drought and drought recovery on macroinvertebrate communities". Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/7137/.
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The effect of drought on freshwater ecosystems is a growing environmental concern. This study aimed to determine the effect of the supra-seasonal 2010-2012 drought on the macroinvertebrate communities and functional feeding groups (FFG) of chalk streams. Three rivers were sampled during and after the drought, three sites were analysed on each river, a perennial control site, a dewatering site (shallow during drought) and a rewetted site (dry during drought). All wetted sites were sampled for macroinvertebrates, algae, velocity and depth monthly. In addition an in-situ experiment investigated grazing rates in dewatering, rewetted and perennial sites and a mesocosm experiment investigated the effect of reduced water velocity and temporary drying on grazing function and macroinvertebrate mortality. Macroinvertebrate data were analysed for structural and functional changes in communities and algal data were analysed for changes of biomass both during drought and recovery. Both found rapid recovery post-drought with high incidence of resilience in the macroinvertebrate communities. Functional recovery was determined by investigating grazing rates in dewatering, rewetted and perennial sites. Algal and macroinvertebrate biomass, and grazing function recovered within a month of rewetting. Despite a rapid recovery of overall biomass and grazing function, FFG results showed delayed effects, and four months following drought differences were still present. Mesocosm experiments showed that macroinvertebrate mortality increased due to dewatering for some species, however slower velocity had little effect. Thus, this study showed that ecological function can return despite changes to macroinvertebrate community structure, indicating that functional redundancy promotes the resilience of chalk stream communities to drought.
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Dube, Carolina. "The impact of Zimbabwe's drought policy on Sontala rural community in Matabeleland South Province /". Link to the online version, 2008. http://hdl.handle.net/10019/1768.
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Driver, Lucas J. "Dynamics of Stream Fish Metacommunities in Response to Drought and Re-connectivity". Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc804923/.
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This dissertation investigates the spatio-temporal dynamics of intermittent stream fish metacommunities in response drought-induced fragmentation and re-connectivity using both field and experimental approaches. A detailed field study was conducted in two streams and included pre-drought, drought, and post-drought hydrological periods. Fish assemblages and metacommunity structure responded strongly to changes in hydrological conditions with dramatic declines in species richness and abundance during prolonged drought. Return of stream flows resulted in a trend toward recovery but ultimately assemblages failed to fully recover. Differential mortality, dispersal, recruitment among species indicates species specific responses to hydrologic fragmentation, connectivity, and habitat refugia. Two manipulative experiments tested the effects of drought conditions on realistic fish assemblages. Fishes responded strongly to drought conditions in which deeper pools acted as refugia, harboring greater numbers of fish. Variability in assemblage structure and movement patterns among stream pools indicated species specific habitat preferences in response predation, resource competition, and desiccation. Connecting stream flows mediated the impacts of drought conditions and metacommunity dynamics in both experiments. Results from field and experimental studies indicate that stream fish metacommunities are influenced by changes in hydrological conditions and that the timing, duration, and magnitude of drought-induced fragmentation and reconnecting stream flows have important consequences metacommunity dynamics.
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Kebede, Yohannes. "Economic evaluation of post-drought recovery agricultural project : the case of Tegulet and Bulga District, Shoa Province, Ethiopia". Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63894.
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Tahkokorpi, M. (Marjaana). "Anthocyanins under drought and drought-related stresses in bilberry (Vaccinium myrtillus L.)". Doctoral thesis, University of Oulu, 2010. http://urn.fi/urn:isbn:9789514262050.
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Abstract
The aim was to study the effects of drought and indirect drought-related stresses on anthocyanin content in bilberry (Vaccinium myrtillus L.). Anthocyanin content was also studied in relation to developmental stage (juvenile vs. mature leaves, previous vs. current-year stems). It was hypothesised that drought-stressed plants accumulate anthocyanins, but their direct role in osmotic regulation was questioned.
Direct drought was created by preventing water supply. Freezing-induced dehydration was accomplished by removal of snow. Effects of summertime chilling (+2 °C during active growth, +5/0 °C during frost hardening) on water status were tested. The trace metal Nickel (Ni) was applied to the soil, as Ni may interfere with plant water relations at the rhizospheric level. Salt (Na+) was added to the soil to observe salt-induced disturbance in osmotic balance and ion homeostasis.
Tissue water content (TWC) decreased and anthocyanin level increased under direct drought, especially in the mature leaves. The freezing-stressed plants contained the same TWC and anthocyanin levels in mid-winter compared to plants that overwintered below snow. The freezing-stressed plants had lower TWC and a similar anthocyanin level in early spring, and lower TWC and anthocyanin level in late spring than plants that overwintered below snow. In the summer and autumn following snow removal, current-year stems of freezing-stressed plants had the same TWC, but higher levels of anthocyanins than current-year stems of plants that overwintered below snow. New growth was thus affected by the freezing stress experienced by previous-year stems. Chilling had no effect on anthocyanins. Although TWC decreased and anthocyanin level increased from active growth to the beginning of frost hardening, no increase was observed during frost hardening. Ni did not cause drought stress in the aboveground shoots, but anthocyanin level decreased in the aboveground shoots along with Ni accumulation in the belowground stems. Na+ increased TWC in the belowground stems, but decreased TWC and anthocyanin level in the aboveground stems.
It is proposed that anthocyanins do not have direct role in osmotic regulation, or in the development of freezing tolerance. It is suggested that the increase in anthocyanin level under direct drought stress is mainly due to the photoprotection of chlorophylls by anthocyanins. This is supported by two facts: (1) At increased anthocyanin level in the juvenile leaves, chlorophyll a was stabilized despite continuing drought stress, and (2) after the initial peak in the mature leaves, the accumulation of anthocyanins ceased although the drought became more severe. As chlorophyll a decreased in the mature leaves due to senescence, there was less demand for such high levels of anthocyanins.
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Leelaruban, Navaratnam. "Spatial Scale Dependence of Drought Characteristics and Impact of Drought on Agriculture and Groundwater". Diss., North Dakota State University, 2016. http://hdl.handle.net/10365/25912.
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Drought is a water related natural hazard. It is difficult to characterize drought because of its diffused nature and spatiotemporal variability. However, understanding the variability of drought characteristics such as severity, frequency, duration, and spatial extent is critical in drought mitigation and planning. Impact of drought on agriculture, water supply, and energy sectors has been long-recognized. The current understanding of drought and its impact is limited due to its complex characteristics and ways in which it impacts various sectors. This study focuses on two important aspects of drought: variability of drought characteristics across different spatial scales, and impact of droughts on crop yield and groundwater. Two drought indices, one integrating severity and spatial coverage, and also taking into account the type of specific crops, were investigated for county level use. The developed indices were used in studying drought at the county level, and its impact on crop yields. These indices can be used for resource allocation at the county level for drought management. Drought is reported in the United States (U.S.) for different administrative units at different spatial scales. The variation of drought characteristics across different spatial scales and scale dependence was investigated, demonstrating the importance of considering spatial scales in drought management. A methodology is proposed to quantify the uncertainty in reported values of drought indices using geostatistical tools. The uncertainty was found to increase with increasing spatial scale size. Artificial Neural Network and regression methods were used to model the impact of drought on crop yield and groundwater resources. Relationships of crop yields and groundwater levels with drought indices were obtained. Overall, this study contributes towards understanding of the spatial variation of drought characteristics across different spatial scales, and the impact of drought on crop yields and groundwater levels.North Dakota Water Recourses Research Institute (ND WRRI) Fellowship Program
North Dakota State University Graduate School Doctoral Dissertation Award
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Cox, Jonathan Peter. "Hydrometeorological aspects of drought management". Thesis, University of Salford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386429.
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Osman, Mohamoud, Albert Dobrenz, Haile Tewolde i Robert Voigt. "Drought Tolerance in Pearl Millet". College of Agriculture, University of Arizona (Tucson, AZ), 1986. http://hdl.handle.net/10150/200578.
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Gutiérrez, Hernández Julián Eli. "Drought Indices in Panama Canal". Master's thesis, Česká zemědělská univerzita v Praze, 2015. http://www.nusl.cz/ntk/nusl-258961.
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Panama has a warm, wet, tropical climate. Unlike countries that are farther from the equator, Panama does not experience seasons marked by changes in temperature. Instead, Panama's seasons are divided into Wet and Dry. The Dry Season generally begins around mid-December, but this may vary by as much 3 to 4 weeks. Around this time, strong northeasterly winds known as "trade winds" begin to blow and little or no rain may fall for many weeks in a row. Daytime air temperatures increase slightly to around 30-31 Celsius (86-88 Fahrenheit), but nighttime temperatures remain around 22-23 Celsius (72-73 Fahrenheit). Relative humidity drops throughout the season, reaching average values as low as 70 percent. The Wet Season usually begins around May 1, but again this may vary by 1 or 2 weeks. May is often one of the wettest months, especially in the Panama Canal area, so the transition from the very dry conditions at the end of the Dry Season to the beginning of Wet Season can be very dramatic. With the arrival of the rain, temperatures cool down a little during the day and the trade winds disappear. Relative humidity rises quickly and may hover around 90 to 100% throughout the Wet Season. Drought forecasts can be an effective tool for mitigating some of the more adverse consequences of drought. The presented thesis compares forecast of drought indices based on seven different models of artificial neural networks model. The analyzed drought indices are SPI and SPEI-ANN Drought forecast, and was derived for the period of 1985-2014 on Panama Canal basin; I've selected seven of sixty-one Hydro-meteorological networks, existing in the Panama Canal basin. The rainfall is 1784 mm per year. The meteorological data were obtained from the PANAMA CANAL AUTHORITY, Section of Water Resources, and Panama Canal Authority, Panama. The performance of all the models was compared using ME, MAE, RMSE, NS, and PI. The results of drought indices forecast, explained by the values of seven model performance indices, show, that in Panama Canal has problem with the drought. Even though The Panama is generally seen as a wet country, droughts can cause severe problems. Significant drought conditions are observed in the index based on precipitation and potential evaporation found in this thesis; The Standardized Precipitation Index (SPI), the Standardized Precipitation Evapotranspiration Index (SPEI), were used to quantify drought in the Panama Canal basin, Panama Canal, at multiple time scales within the period 1985-2014. The results indicate that drought indices based on different variables show the same major drought events. Drought indices based on precipitation and potential evaporation are more variable in time while drought indices based on discharge. Spatial distribution of meteorological drought is uniform over Panama Canal.
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Ren, Xiaomeng, i University of Lethbridge Faculty of Arts and Science. "Agricultural vulnerability to drought in southern Alberta : a quantitative assessment". Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2007, 2007. http://hdl.handle.net/10133/398.
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Agricultural vulnerability is generally referred to as the degree to which agricultural systems are likely to experience harm due to a stress. In this study, an existing analytical method to quantify vulnerability was adopted to assess the magnitude as well as the spatial pattern of agricultural vulnerability to varying drought conditions in Southern Alberta. Based on the farm reported data and remote sensing imagery, two empirical approaches were developed to implement vulnerability assessment in Southern Alberta at the quarter-section and 30 meter by 30 meter pixel levels. Cereal crop yield and the Standardized Precipitation Index (SPI) were specified as the agricultural wellbeing and stress pair in the study. Remote sensing data were used to generate cereal crop yield estimations, which were then implemented in vulnerability quantification. The utility of the remote sensing data source for vulnerability assessment were proved. The spatial pattern of agricultural vulnerability to different severity and duration of drought were mapped.xii, 127 leaves : ill. ; 29 cm.
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Ocheltree, Troy W. "Growth and survival during drought: the link between hydraulic architecture and drought tolerance in grasses". Diss., Kansas State University, 2012. http://hdl.handle.net/2097/13803.
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Doctor of PhilosophyDepartment of Agronomy
P.V. Vara Prasad
The pathway for the movement of water through plants, from the soil matrix to the atmosphere, constitutes the hydraulic architecture of a plant. The linkage between the hydraulic architecture of woody plants and drought tolerance has received considerable attention, but much less work has been done on grasses. I investigated the linkage between the hydraulic architecture of grasses to physiological patterns of water use across a range of species and conditions. The rate of stomatal conductance (g[subscript]s) and photosynthesis (A) increased acropetally along the leaves of 5 grass species, which is a unique feature of this growth form. The internal structure of leaves also changed acropetally in order to minimize the pressure gradient across the mesophyll that would otherwise occur as a result of increasing g[subscript]s. The resistance to water movement through the mesophyll represented 80-90% of leaf resistance in six genotypes of Sorghum bicolor L. (Moench). This resistance was most important in controlling g[subscript]s and A when water was readily available, but as soil-moisture decreased it was the efficient transport of water through the xylem that was most important in maintaining plant function. I also investigated the relationship between hydraulic architecture and stomatal responses of grasses to increasing Vapor Pressure Deficit (D). Grasses with a larger proportion of their hydraulic resistance within the xylem were less sensitive to increasing D and plants with high root conductance maintained higher rates of gas exchange D increased. Finally, I investigated the tolerance of grasses to extreme drought events to test if there was a trade-off between drought tolerance and growth in grasses. Plants with drought tolerant leaf traits typically sacrificed the ability to move water efficiently through their leaves. Having drought tolerant leaves did not limit the plants ability to have high rates of gas exchange, and, in fact, the most drought tolerant plants had the high rates of g[subscript]s when expressed on a mass basis. Leaf-level drought tolerance did contribute to species’ occurrence, as the drought intolerant species I studied are not commonly found in low precipitation systems. The results presented here highlight the importance of studying the hydraulic architecture of plants to provide a better understanding of what controls plant function across a range of environmental conditions.
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Gebeyehu, Setegn. "Physiological response to drought stress of common bean (Phaseolus vulgaris L.) genotypes differing in drought resistance". Göttingen Cuvillier, 2006. http://geb.uni-giessen.de/geb/volltexte/2006/3726/index.html.
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Moore, David L. "Reservoir management during drought an expert system approach". Ohio : Ohio University, 1993. http://www.ohiolink.edu/etd/view.cgi?ohiou1175718241.
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Stenson, Jennifer R. "A study of hydrologic drought using streamflow as an indicator". Ohio : Ohio University, 1989. http://www.ohiolink.edu/etd/view.cgi?ohiou1182521390.
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Stahl, Kerstin. "Hydrological drought a study across Europe /". [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963810138.
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Matthews, Cushla Emilja. "Drought contingency planning in Ontario muncipalities". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ61925.pdf.
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Cook, H. F. "Assessment of drought resistance in soils". Thesis, University of East Anglia, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374255.
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Gillespie, Jason Carter. "Assessing Drought Flows For Yield Estimation". Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/30926.
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Determining safe yield of an existing water supply is a basic aspect of water supply planning. Where water is withdrawn from a river directly without any storage, the withdrawal is constrained by the worst drought flow in the river. There is no flexibility for operational adjustments other than implementing conservation measures. Where there is a storage reservoir, yields higher than the flow in the source stream can be maintained for a period of time by releasing the water in storage. The determination of safe yield in this situation requires elaborate computation.
This thesis presents a synthesis of methods of drought flow analysis and yield estimation. The yield depends on both the magnitude of the deficit and its temporal distribution. A new Markov chain analysis for assessing frequencies of annual flows is proposed. The Markov chain results compare very well with the empirical data analysis. Another advantage of the Markov chain analysis is that both high and low flows are considered simultaneously; no separate analyses for the lower and upper tails of the distribution are necessary.
The temporal distribution of drought flows is considered with the aid of the generalized bootstrap method, time series analysis, and cluster sequencing of worsening droughts called Waittâ s procedure. The methods are applied to drought inflows for three different water supply reservoirs in Spotsylvania County, Virginia, and different yield estimates are obtained.Master of Science
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Harb, Amal Mohammad. "Dissection of Drought Responses in Arabidopsis". Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/77148.
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Plants as sessile organisms are susceptible to many environmental stresses such as drought, and salinity. They have therefore evolved mechanisms to acclimate and tolerate environmental stresses. Knowledge of the molecular aspects of abiotic stress gleaned from extensive studies in Arabidopsis has provided much information on the complex processes underlying plant response to abiotic stresses. Nevertheless, there is a need for integration of the knowledge gained and a systematic molecular genetic dissection of the complex responses to abiotic stress. In this study in Arabidopsis, comparative expression profiling analysis of progressive (pDr) and moderate (mDr) drought treatments revealed common drought responses, as well as treatment specific signatures responses to drought stress. Under prolonged moderate drought plants develop different mechanisms for acclimation: induction of cell wall loosening at early stage, and a change in hormonal balance (ABA: JA) at late stage of moderate drought. Taking a reverse genetics approach, a MYB transcription factor (MYB109) has been identified as a regulator of growth under drought and salt stress. Global expression profiling showed possible mechanisms of how MYB109 modulates growth under drought conditions: as a regulator of RNA processing and splicing and as a negative regulator of jasmonic acid biosynthesis and signaling. A forward genetics screen for drought and salt tolerance of transposon activation tag (ATag) lines led to the discovery of novel genes, which shed light on unexplored areas of abiotic stress biology. Utilizing this strategy, a potential role for cell wall modification and MATE transporters in response to drought and salt stress has been discovered, which needs further analysis to integrate this information on the role of these biological processes in plant stress biology.Ph. D.
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King, James Allen. "Optimal reservoir operation for drought management". Ohio University / OhioLINK, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1183649698.
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Parham, Antoinette D. "Drought: Construction of a Social Problem". Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc955027/.
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Drought is a complex subject that has varied definitions and perspectives. Although drought has historically been characterized as an environmental problem from both the meteorological and agricultural communities, it is not considered a sociological disaster despite its severe societal impacts. Utilizing the framework developed by Spector and Kitsuse (2011) and Stallings (1995), this research examines the process through which drought is defined as a social problem. An analysis of the data revealed drought was well covered
in Africa, India, China, Australia, and New Zealand, yet very little coverage
focused on the United States. There were less than 10 articles discussing
drought and drought impacts in the United States. The workshops/meetings examined also were lacking in the attention to drought, although their overall theme was focused on hazards and resilience. Six sessions in over 16 years of
meetings/workshops focused on the topic of drought, and one session was focused on the condition in Canada. The interviews uncovered five thematic areas demonstrating drought understanding and awareness: Use of outreach to get the message out; agricultures familiarity with drought; the role of drought in media; the variability of what drought is; and water conservation. Drought's claims-makers who are dedicated to providing outreach and education to impacted communities. Drought is often overlooked due to its slow onset and evolving development makes it difficult to determine when to engage in recovery efforts. Drought defined as a social problem also expands theoretical conversations regarding what events or issues should be included within the sociological disaster list of topics.
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Ray, Dennis, i Margaret Livingston. "Response of Guar to Drought Conditions". College of Agriculture, University of Arizona (Tucson, AZ), 1986. http://hdl.handle.net/10150/200577.
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Plants with greater drought tolerance will increase crop production in many areas of the world. The purpose of this study was to examine the physiological responses of guar, a drought tolerant plant, under water stress. The dry treatment received only one irrigation and yielded respectably. This treatment maintained turgor and metabolic functions throughout the study by decreasing transpiration rate and increasing diffusive resistance.
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McDaniel, R. G., i A. K. Dobrenz. "Physiological Studies of Cotton Drought Tolerance". College of Agriculture, University of Arizona (Tucson, AZ), 1992. http://hdl.handle.net/10150/208659.
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We evaluated an array of progeny of interspecific cotton crosses in the field. Significant water stress was placed on the plants in mid-summer by withholding water supplied by drip irrigation during plant development earlier in the season. A number of physiological measurements were carried out on selected individual plants of this population during the several week period of imposed drought stress. Overall results confirm that a large degree of variation exists within the population for all traits measured. Initial carbon isotope discrimination measurements suggest this trait may prove useful in estimating transpiration efficiency of cotton genotypes.
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BIANCHI, DAVIDE. "GRAPEVINE ROOTSTOCK CHARACTERIZATION FOR DROUGHT TOLERANCE". Doctoral thesis, Università degli Studi di Milano, 2021. http://hdl.handle.net/2434/896313.
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Grapevine is worldwide grafted on rootstocks to create a biological barrier to the phylloxera (Daktulosphaira vitifoliae). Despite the key role of rootstock in the adaptation to environmental conditions, a limited number of genotypes is available for winegrowers, showing a narrow genetic background. The gap between the importance of rootstocks in abiotic stress tolerance and their low genetic variability leads to consider rootstock breeding as a promising strategy to face climate change. In the last decades, new breeding programs were developed with the aim to provide new rootstocks able to cope with drought and other abiotic stresses. Nowadays, the continuous progress in genetic techniques can assist and accelerate the selection process of new tolerant genotypes.
In the present PhD project, several genotypes at different stages in rootstock selection process were analyzed for drought tolerance. The first part of the thesis focused on 3 genotypes belonging to the recent M-series, the second part was about a new selection of 30 genotypes, coming from different breeding programs, and in the last part a breeding population of 141 genotypes was used for a genome wide association study (GWAS).
The new M-rootstocks (M1, M3 and M4), recently placed on the market, were compared to traditional rootstocks, in order to better understand their behavior under drought. In a pot experiment under controlled conditions, M1, M3 and M4 were compared to nine rootstocks with different genetic background at decreasing levels of water availability. M-rootstock performance under water deficit was similar to the tolerant rootstocks 1103P and 110R, in both phenotypic and genetic responses to water stress. These rootstocks adopted a strategy of tolerance to face water stress, increasing the water use efficiency (WUE) under deficit conditions. To deeply investigate the behavior of tolerant rootstocks under drought, a second experiment in semi-controlled conditions was set up, comparing M4 to 1103P under progressive water deficit, in grafting combination with V. vinifera cv Pinot Blanc. Similar performances were reported by the two grafting combinations under mild to moderate water deficit, but a different response occurred under sever conditions: 1103P reduced stomatal conductance, transpiration, and carbon assimilation more than M4, which was able to preserve water use efficiency and operating efficiency of photosystem II.
In the second part of the thesis 30 new selected genotypes were compared to rootstock M2 for water stress tolerance and nutritional status, in order to characterize the rootstock material before the marketing process and to identify new pre-breeding material. The experiment was carried out in un-grafted conditions for two years and in two experimental fields, characterized by different water availability. Several parameters were analyzed, such as transpiration, WUE, vigor, macronutrients and micronutrients in the leaves. Genotypes ranked for both abiotic stresses and the differences between the two sites allowed to estimate their plasticity for each trait.
Finally, a GWA approach was applied on a breeding population, counting 141 genotypes, in order to identify the genomic regions involved in drought tolerance. The population was genotyped with a 18k SNP array, after the validation on non-vinifera germplasm, belonging to a rootstock core-collection of 70 genotypes. Three phenotyping cycles under increasing water deficit were performed on the breeding population under greenhouse-controlled conditions. Vigor, shoot growth rate, transpiration, stomatal conductance and leaf turgor were estimated for each genotype at different water deficit levels. A group of tolerant genotypes with high performance under water deficit condition was identified and used in GWAS approach to detect the loci associated to drought tolerance of rootstocks.
In conclusion, this work enhanced the knowledge about rootstock response to water deficit, characterized the water tolerance of a large panel of rootstocks and identified potential target genes for future breeding programs.
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Ahmadi, Behzad. "On the Drought Recovery and Resiliency: How Terrestrial and Riverine Ecosystems Recover from Agricultural and Hydrological Droughts". PDXScholar, 2019. https://pdxscholar.library.pdx.edu/open_access_etds/4834.
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Climate extremes, in particular droughts are significant driving forces towards riverine and terrestrial ecosystems disturbance. Drought impacts on stream ecosystems include losses that can either be direct (e.g. destruction of habitat for aquatic species) or indirect (e.g. deterioration of water quality, soil quality, and increased chance of wildfires). This study investigates hydrological and agricultural droughts and their recovery durations. For the riverine ecosystems, this study combines hydrologic drought and water quality changes during droughts and represents a multi-stage framework to detect and characterize hydrological droughts, while considering water quality parameters. Hydrological droughts are categorized into three stages of growth, persistence, retreat, and water quality variables (i.e., water temperature, dissolved oxygen concentration, and turbidity) are utilized to further investigate drought recovery. The framework is applied to 400 streamflow gauges across the Contiguous United States (CONUS) over the study period of 1950-2016. The framework is assessed and validated based on three drought events declared by the state of California in 2002, 2008, and for the 2012 US drought, which affected most of the nation. Results reveal the duration, frequency, and severity of historical droughts in various regions, additionally, duration of each stage of drought (i.e., growth, persistence, and retreat) is also assessed and the spatial patterns are diagnosed across the CONUS. Varied drought recovery durations are perceived for different water quality variables, and in general, it takes about two more months for water quality variables to recover from a drought, following the hydrological drought termination. For the terrestrial ecosystem, this study evaluated drought impacts on gross primary productivity (GPP), evapotranspiration (ET), and water use efficiency (WUE = GPP/ET) of different terrestrial ecosystems over the CONUS, as well as the drought-recovery during the period of 2000 to 2014. The response of WUE to drought showed large differences in various regions and biomes. WUE for arid ecosystems typically showed a positive response (increase) to drought, whereas WUE for humid ecosystems showed both positive and negative response to drought. The results revealed that WUE is correlated with drought severity, and for more severe droughts, WUE changes more significantly. Furthermore, terrestrial drought recovery shows a positive correlation with drought severity and in regions that experienced more severe drought episodes, ecosystem requires longer period to recover.
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Bergman, Crystal Jane. "A Survey of Drought Impacts and Mitigation Planning in Kentucky". TopSCHOLAR®, 2009. http://digitalcommons.wku.edu/theses/95.
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Karlina. "ASSESSMENT OF HYDRO-METEOROLOGICAL DROUGHTS RELATED TO ENSO IN LOMBOK AND SUMATRA ISLANDS, INDONESIA". Kyoto University, 2018. http://hdl.handle.net/2433/231991.
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付記する学位プログラム名: グローバル生存学大学院連携プログラムKyoto University (京都大学)
0048
新制・課程博士
博士(工学)
甲第21058号
工博第4422号
新制||工||1687(附属図書館)
京都大学大学院工学研究科社会基盤工学専攻
(主査)教授 寶 馨, 教授 堀 智晴, 准教授 佐山 敬洋
学位規則第4条第1項該当
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Lennard, A. T. "An investigation of drought in the Severn Trent Water region : re-evaluating drought severity, characteristics and generating mechanisms". Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3004783/.
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Díaz, Loaiza Manuel Andrés. "Drought and flash floods risk assessment methodology". Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/325143.
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Floods and Drought are some of the most catastrophic natural disasters for humanity, averaging 1 to 5 billion dollar of annually damage for flood events and 6 to 8 billion dollars respectively for drought events. To avoid this phenomena risk management science has grown in the last years and allows us to assess the risk and the possible benefits if some specific measures are implemented (e.g. mitigation / adaptation measures). A methodology for Non-Structural Measures (NSM) implementation in risk assessment has been developed for flood event management. Likewise, an uncertainty analysis has been done in order to identify the variation of the possible results in the risk assessment. An analysis has been done based on the Expected Annual Damage (EAD) to determine the optimal return period of design of a structural measure. A new indicator has been proposed based on this analysis: The Optimal Expected Annual Damage indicator (OEAD).
In the present document the results of pluvial flood risk assessment are described. These results include structural and non-structural measures based on a developed methodology for Arenys de Munt basin, which belongs to the region of Catalonia in Spain. To include non-structural measures in risk assessment, mitigation coefficients where built in the methodology, and are described in the methodology. Also, steps for the optimization of their possible implementation are defined. This research shows that potential economic losses are decreasing with the construction of structural measures from approximately 6.6 M€ to 3 M€ (box culvert of €14Million), and in combination with the implementation of non-structural measures this could even decrease to 0.7 M€ if the non-structural measures are implemented (for 500 year return period event). Related potential casualties results decrease from approx. 11 casualties to 8 and even as low as 2 casualties respectively if non-structural measures are implemented (for 500 year return period). This, demonstrate that non-structural measures are a way to follow in the flood risk mitigation.
For drought events, a new methodology has been developed in order to relate quantitative potential economic losses for rainfed crops with "Meteorological Drought". In the same, a method for the hazard (through the Palmer index) and vulnerability assessment was developed. The susceptibility of a particular crop due to a drought event was linked with a classification of the phenological stages according two seasons: the sowing and harvesting season. The case study was focus on the Llobregat basin, in which both, hydrometeorological and crop statistics data series were available. Results illustrate that the Llobregat basin has suffered at least 2 important periods of drought (2000/2001 and 2005/2006) during the length of the considered 16 year crop production record statistics. These periods of drought caused potential economic losses of approximately 40.13 M€ and 55.84 M€ in the geopolitical subdivision called "Comarcas" of the Llobregat basin. The related methodology, demonstrates coherence in the detection of "important" drought events, and in the quantification of individual potential losses per crop type, which shows that crops, like olives (classified in category woody crop type) are more resistant to drought than vegetables (tomato, lettuce chard etc.). Finally, in addition to the presented methodology the potential losses of crop efficiency curves are proposed, as indicators for agricultural drought risk assessment.Les inundacions i les sequeres són alguns dels desastres més catastròfics per a la humanitat, promitjant anualment al voltant d'1 a 5 x 10³ milions de dòlars i 6 a 8 x 10³ milions de dòlars en pèrdues econòmiques respectivament. Per combatre aquests fenòmens, la ciència de la "gestió del riscs" ha anat desenvolupant al llarg dels últims anys, permetent-nos quantificar el risc i els possibles beneficis en el cas que algunes mesures siguin implementades (tals com mesures de mitigació/adaptació etc.). En el present document es presenta una metodologia per a la quantificació del risc considerant la implementació de mesures no-estructurals (NSM). Així mateix, es va desenvolupar una anàlisi d'incertesa per identificar les fonts de variància sobre els resultats en el càlcul del risc. Amb l'indicador EAD (Expected Annual Damage), es va realitzar una anàlisi per determinar el període de tornada òptima en el disseny de mesures estructurals, com a resultat del mateix, es proposa un nou indicador: l "Optimal Expected Annual Damage" (OEAD). En el present document s'exposen els resultats per a la quantificació del risc pluvial. Aquests resultats inclouen mesures estructurals i no-estructurals d'acord amb la metodologia desenvolupada per a la conca d'Arenys de Munt a Catalunya-Espanya. Per incloure en el càlcul del risc a les mesures no-estructurals, es van desenvolupar coeficients de mitigació els quals són explicats dins de la metodologia. Igualment, es defineixen els passos a seguir per a l'optimització en la implementació d'aquestes mesures. En aquesta investigació, s'il·lustra que les pèrdues potencials econòmiques disminueixen si una mesura estructural és implementada (canalització per Box Culvert de 14 M€), des de 6.6 M€ a 3 M€ (T=500 anys), i si s'implementen mesures no-estructurals en combinació amb la mesura estructural, les pèrdues potencials poden disminuir-se fins a 0.7 M€ per al període de tornada de 500 anys. Sobre les pèrdues potencials de vides humanes, la mitigació obtinguda segueix el mateix comportament que les pèrdues potencials econòmiques, disminuint des d'11 possibles víctimes a 8 amb la mesura estructural i a 2 en combinació amb la mesura no estructural. Pel fenomen de la sequera, es va desenvolupar una metodologia per relacionar la "Sequera Meteorològica" amb les pèrdues potencials econòmiques en cultius de secà. En la mateixa, es proposa un mètode per a la quantificació de la perillositat (mitjançant els índexs de Palmer) i la vulnerabilitat. La susceptibilitat d'un cultiu de secà a un esdeveniment de sequera (vulnerabilitat) es va relacionar fent una classificació d'acord a dos estats fenològics: l'època de sembra i de recol·lecció. El cas d'estudi es va enfocar a la conca del riu Llobregat-Espanya, de la qual es va disposar d'informació hidrometeorològica i de les estadístiques de producció de diferents tipus de cultius de secà. De l'anàlisi realitzada sobre la conca, es va observar que al llarg dels 16 anys d'estadístiques en els cultius, van ocórrer dos períodes importants de sequera (2000/2001 i 2005/2006). Aquests períodes de sequera van deixar respectivament pèrdues potencials econòmiques d'aproximadament 40.13 M€ i 55.84 M€ per a les comarques associades a la conca del riu Llobregat. La metodologia desenvolupada, demostra eficàcia en la detecció d'esdeveniments importants de sequera, així mateix, il·lustra una coherència en la quantificació de les pèrdues individuals en els tipus de cultiu, en les que cultius com l'oliva (classificat com a cultiu llenyós), demostra més resistència a la sequera respecte a altres cultius com l'enciam, tomàquets etc.. Finalment, com a complement a la metodologia desenvolupada, es proposa a les corbes de pèrdua d'eficiència de cultiu, com a indicadors per a la gestió del risc de sequeres en cultius de secà.
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Germain, Richard James. "Drought management using a geographical information system". Ohio : Ohio University, 1996. http://www.ohiolink.edu/etd/view.cgi?ohiou1178651687.
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Teoh, Choo B. "Investigation of drought severity using probabilistic methods". Ohio : Ohio University, 1990. http://www.ohiolink.edu/etd/view.cgi?ohiou1183474312.
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Lloyd-Hughes, Benjamin. "The long range predictability of European drought". Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398414.
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Sack, Lawren. "Plant responses to deep shade plus drought". Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620950.
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Newell, Trenton D. "Drought tolerant corn response to water availability". Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/32674.
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Master of ScienceDepartment of Agronomy
Kraig L. Roozeboom
Due to decreased availability of irrigation water in central and western Kansas and an increase in water restrictions, producers are looking for more efficient ways to use available irrigation water. Drought-tolerant technologies have become popular in hybrids for stress-prone environments across central and western Kansas and are marketed for their ability to produce greater grain yields with less water. The objective of this research was to understand how DT and non-DT corn hybrids respond in a wide range of environmental conditions in terms of soil water status change, canopy indicators of stress, dry matter partitioning, and grain yield. Soil water status change, yield, and canopy response characteristics of two DT hybrids, and one non-DT hybrid were compared at five locations over two years in rain-fed, semi-irrigated, or fully irrigated regimes making a total of 18 environments. Field experiments were established in 2014 and 2015 near Topeka, Scandia, Hutchinson, Garden City, and Tribune, KS. Two corn hybrids with different approaches drought tolerance (Pioneer 1151 AQUAmax, bred drought tolerance and Croplan 6000 DroughtGard, bred drought tolerance plus transgenic drought tolerance), and one hybrid with no specific drought tolerance characteristics but with proven performance in favorable environments (Croplan 6274) were used in the experiment. Soil moisture content (measured using a neutron moisture meter), canopy temperature, ear leaf temperature, and chlorophyll content were measured at tasseling (VT), milk or dough (R3-R4), and physiological maturity (R6) developmental stages. Grain yield was at all 18 environments, and biomass production was estimated at 14 of the environments. Hybrid plasticity of yield results show the response for Croplan 6000DG and Pioneer 1151AM differed, but Croplan 6274 was the same as both other hybrids at the 0.10 alpha level. Yields of all hybrids remained comparable in most environments, but as environment yields increased beyond 200 bu acˉ¹, Croplan 6000DG lagged behind Pioneer 1151AM. Hybrid harvest index plasticity shoed that all hybrids had the same response to environment in harvest index. Although, not statistically significant, when an environment supported favorable harvest index values greater than 0.40, it’s observed that Croplan 6000DG does have an improvement in harvest index relative to the Pioneer 1151AM and Croplan 6274.