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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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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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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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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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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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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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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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Rudebeck, Hugo. "HYDROLOGICAL DROUGHTS IN SWEDEN: Mapping of historical droughts and identificationof primary driving climate variables andcatchment properties." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-350520.
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This study investigated the relationship between hydrological, and to some extent, meteorological droughts, and meteorological variables and catchment characteristics in 235 Swedish catchments between 1983 and 2013. This was done in order to investigate what factors affect the drought sensitivity in Swedish catchments and to map the occurrence of droughts in Sweden between 1983 and 2013. There have been studies about which meteorological phenomena and catchment characteristics that promote hydrological droughts, but for Sweden this is relatively unexplored. To investigate droughts during the study period three indices were used: the Standardized Precipitation Index (SPI), which is an index for meteorological droughts, the Standardized Streamflow Index (SSI), which predicts hydrological droughts and a threshold index for streamflow droughts. These indices were used to identify the number of drought events and the total number of drought days. For the majority of the 235 Swedish catchments there were no significant trends for the number of drought events or the total number of drought days during the 30-year period. The SPI and the SSI were found to correlate best in time when adding a one-month lag period to the SSI time series. The correlations between the indices and the meteorological variables and the catchments properties varied depending on how the catchments were grouped according to latitude or elevation. For example, the number of drought events was positively correlated to the mean elevation of the catchments in north and central Sweden when using the SSI while there were no significant correlations with elevation in southern Sweden. Another example is that it was almost only in northern Sweden where significant correlations between the percentage of bedrock and drought characteristics were identified. The percentage of bedrock can be used as an indication for how much groundwater a catchment can store. The correlations also look different for the different indices. For example, when looking at all catchments together the number of drought events identified with the SPI was negatively correlated to latitude and mean elevation while the number of drought events identified with the SSI was positively correlated to the same variables. For further research into this topic it would be wise to study winter and summer droughts separately to better identify which are the driving variables.I den här studien undersöktes sambanden mellan hydrologiska, och till viss del meteorologiska, torrperioder och bakomliggande meteorologiska drivvariabler och avrinningsområdesegenskaper i 235 svenska avrinningsområden mellan 1983 och 2013. Detta gjordes i syfte att undersöka vilka faktorer som påverkar känsligheten för torka i svenska avrinningsområden och för att kartlägga förekomsten av torrperioder i Sverige mellan 1983 och 2013. Internationellt finns det studier på vilka meteorologiska fenomen och egenskaper hos avrinningsområden som leder till risk för fler torrperioder, men för Sverige är det ett relativt outforskat område. För att undersöka torrperioder under den aktuella perioden användes tre index: Standardized Precipitation Index (SPI), vilket är ett index för meteorologiska torrperioder, Standardized Streamflow Index (SSI), som används för hydrologiska torrperioder och ett tröskelvärdes-index för att identifiera hydrologisk torka. Indexen användes för att identifiera antalet torrperioder och totala antalet dagar med torka under studieperioden. För majoriteten av de 235 avrinningsområdena gick det inte att se några signifikanta trender för antalet torrperioder eller totala antalet dagar med torka under perioden 1983-2013. SPI och SSI korrelerade bäst med varandra över tiden när SSI-tidsserien försköts med en månad. Korrelationerna mellan torrperioderna identifierade med de olika indexen och de meteorologiska variablerna och avrinningsområdesegenskaperna varierade beroende på hur avrinningsområdena grupperades efter latitud eller medelhöjd. Till exempel, i norra och centrala Sverige korrelerade antalet torrperioder för SSI positivt med medelhöjden medan det i södra Sverige inte fanns några signifikanta korrelationer. Ett annat exempel är att det nästan bara var i norra Sverige som det fanns korrelationer mellan procenten berggrund och de identifierade torrperiodsegenskaperna. Procenten berggrund i jordlagret kan användas som en indikation på hur mycket grundvatten som kan lagars i ett avrinningsområde. Korrelationerna skiljde sig också åt för de olika indexen. Till exempel, sett över alla avrinningsområden så var antalet torrperioder beräknat med SPI negativt korrelerade med latitud och medelhöjd medan antalet torrperioder beräknat med SSI var positivt korrelerade med dessa egenskaper. För vidare forskning inom detta område rekommenderas att titta separat på vinter- och sommartorkor för att bättre kunna identifiera potentiella drivvariabler.
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Ren, Xiaomeng, and 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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Stockton, Charles W., David M. Meko, and William R. Boggess. "Drought History and Reconstructions from Tree Rings." Laboratory of Tree-Ring Research, University of Arizona (Tucson, AZ), 1989. http://hdl.handle.net/10150/302684.
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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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Watson, Thomas J. "Wind River Basin, Wyoming streamflow reconstructions." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1400958981&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Yu, Rita Man Sze. "European droughts under climate change : projections and uncertainties." Thesis, University of East Anglia, 2013. https://ueaeprints.uea.ac.uk/47923/.
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Droughts are one of the most damaging natural hazards, and anthropogenic climate change has and will continue to alter their characteristics. Better understanding of changes in drought characteristics under potential future climates is vital for managing drought risks and impacts, yet projections are very uncertain. This thesis examines the effects of climate change on European drought characteristics through a multi-scenario and multimodel approach. It explores the uncertainty associated with emission scenarios, global and spatial climate projections, and with the identification and characterisation of droughts. Climate projections simulated by the simple climate model MAGICC6.0 and patternscaling climate scenario generator ClimGen are assessed, emulating eighteen CMIP3 general circulation models (GCMs) under ten emission scenarios. Drought severity (magnitude times duration) and spatial extent are analysed for both 3-month and 12-month events. Drought projections vary substantially depending on the GCM, emission scenario, region, season and definition of drought. Overall, climate change enhances drought conditions across the study region, with marked increases simulated for the southern latitudes; reductions are projected for the northern latitudes, especially in winter and spring. Perturbations in the interannual variability of precipitation tend to enhance drought conditions caused by mean precipitation changes, or to moderate or reverse their reductions. Hydrological drought parameters are highly sensitive to potential evapotranspiration (PET), which shows the importance of the PET calculation method. Greater agreement in the direction of change tends to occur in the high- and low-latitudes, and in summer and autumn. Both meteorological and hydrological drought results generally indicate the same direction of change, with the latter having larger magnitudes. Projection ranges tend to increase with time and magnitude of warming; intra-GCM spread dominates other sources of uncertainty. The implications of the large uncertainties include that decision-making should be based on multi-scenario and multi-model results, and with consideration of drought definition.
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Rahiz, Muhammad. "Droughts in future climate change in the UK." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:cde09ece-1da9-4374-964e-ebea462bc956.
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This thesis seeks to investigate the changes in the characteristics of 20th and 21st century meteorological droughts in the UK to address the following lines of inquiry: 1) How credible are rainfall-based indices in representing hydrological droughts, 2) How coherent are droughts?, 3) Can alternative method of analysis provide new (or additional) information on the uncertainties in climate models?, and 4) Will future drought characteristics change?. Key results, respectively, are summarized as follows: • The drought severity index (DSI), can be considered a good proxy for assessing hydrological droughts as can be seen in its ability to capture the major hydrological events. The main caveat of the DSI is that there is often an underestimation of drought intensity and duration, • Drought covariance is higher for the (i) wet season, (ii) moderate and (iii) shorter duration droughts, • Evaluating climate models using drought statistics produces contrasting results compared with that using the model's precipitation fields. Drought statistics show biases which are largely negative, more intense, and have a greater spatial coverage. • The projected ensemble-mean change is generally greater (and more widespread) for (i) moderate droughts and (ii) wet season compared with extreme droughts and the dry season, respectively with increases in drought intensity, drought covariance index, frequency of drought months and frequency of drought events for a given duration shown for England.
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Ujeneza, Eva Liliane. "Simulating the characteristics of droughts in Southern Africa." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/9102.
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Includes bibliographical references.Drought is widely considered as one of the most devastating natural disasters in the world. In particular, drought is a big threat in Southern Africa because the economy of most of the population in the region is based on rain-fed agriculture. Previous studies have projected that global warming may enhance the frequency and intensity of droughts over Southern Africa in the future. However, the credibility of this projection depends on the ability of the global and regional climate models (GCMs and RCMs) in simulating the characteristics of drought. This thesis presents the characteristics of the Southern African droughts and evaluates the capability of global and regional climate models in simulating these characteristics. The thesis used a multi-scaled standardized drought index (called standardized precipitation evapo-transpiration index, SPEI) in characterizing droughts at 3- and 12-month scales over Southern Africa. The spatial patterns of the droughts are identified using the principal component analysis (PCA) on the SPEI, while the temporal characteristics of the drought patterns are studied using wavelet analysis. The relationship between each drought pattern and global SSTs (and climate indices) is quantified using correlation analysis and wavelet coherence analysis. The study uses correlation analysis to quantify the capability of the models in simulating the drought patterns.
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Boushaki, Farid Ishak. "Statistical relationship between drought indices and NDVI at regional scale." Thesis, The University of Arizona, 2002. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0192_sip1_w.pdf&type=application/pdf.
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Henderson, Carol Elaine. "Life in the land of death famine and drought in arid Western Rajasthan /." [S.l. : s.n.], 1988. http://catalog.hathitrust.org/api/volumes/oclc/53916457.html.
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Tarhule, Aondover Augustine. "Droughts, rainfall and rural water supply in northern Nigeria." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ30174.pdf.
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Tully, Craig David. "Holocene Mega-Droughts in the Central Atacama Desert, Chile." Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1272312883.
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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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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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Schmitt, Catherine. "The Effects of the 2001-2002 Drought on Maine Surface Water Supplies." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/SchmittC2003.pdf.
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Cloud, Kimberly C. "Changes and trends in streamflow during floods and droughts in the urbanizing Christina River Basin." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 131 p, 2007. http://proquest.umi.com/pqdweb?did=1397904211&sid=9&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Barnett, Faires Anthony. "Upper Green River Basin streamflow reconstructions and drought variability." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1445046271&sid=9&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Follum, Michael Lee. "Upper Green River Basin precipitation reconstructions and drought analysis." Laramie, Wyo. : University of Wyoming, 2009. http://proquest.umi.com/pqdweb?did=1798481411&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Guion, Antoine. "Droughts and heatwaves in the Western Mediterranean, impact on ozone pollution." Electronic Thesis or Diss., Sorbonne université, 2022. http://www.theses.fr/2022SORUS056.
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Sécheresses et vagues de chaleur sont des événements extrêmes capables d’impacter à la fois la végétation et la chimie de l’atmosphère, notamment par l’intermédiaire d’interactions entre la surface et la troposphère. L’objectif de cette thèse est d’évaluer leurs effets sur la biomasse, l’activité des incendies et la pollution à l’ozone dans l’Ouest Méditerranéen. Cette étude se base principalement sur des modèles numériques régionaux de la surface terrestre (hydrologie et végétation) et de l'atmosphère (météorologie et chimie atmosphérique). En complément, plusieurs jeux de données d’observations in situ et satellitaires sont utilisés.Identifiant sécheresses et vagues de chaleur sur la période 1979-2016 (WRF-ORCHIDEE), j’ai mis en avant leur distribution spatiale et temporelle. Sur base d’observations (MODIS), j’ai démontré que le déclin de l’activité végétale (diminution de la biomasse) est principalement attribuable aux sécheresses alors que l’augmentation en intensité des incendies résulte d’une synergie entre sécheresses et canicules. Finalement, ces événements mènent tous deux à une augmentation de la concentration de surface en ozone incluant des pics de pollution simulés (CHIMERE) et observés (AQ e-Reporting). Ceci s’explique par une augmentation des émissions de précurseurs, une diminution du dépôt sec dans la canopée et des conditions météorologiques favorablesDroughts and heatwaves are extreme events able to affect both vegetation and atmospheric chemistry, notably through surface-troposphere interactions. The objective of this thesis is to assess their effects on biomass, fire activity and ozone pollution in the western Mediterranean. This study is mainly based on regional numerical models of the land surface (hydrology and vegetation) and the atmosphere (meteorology and atmospheric chemistry). In addition, several datasets of in situ and satellite observations are used.Identifying droughts and heatwaves over the period 1979-2016 (WRF-ORCHIDEE), I highlighted their spatial and temporal distribution. Based on observations (MODIS), I demonstrated that the decline in vegetation activity (decrease in biomass) is mainly attributable to droughts, while the increase in fire intensity results from a synergy between droughts and heatwaves. Finally, these events both lead to an increase in surface ozone concentration including simulated (CHIMERE) and observed (AQ e-Reporting) pollution peaks. This is explained by an increase in precursor emissions, a decrease in dry deposition in the canopy and favourable meteorological conditions for photochemistry
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Isarangkool, Na Ayutthaya Supat. "Change of whole-tree transpiration of mature Hevea brasiliensis under soil and atmospheric droughts : analyze in intermittent and seasonal droughts under the framework of the hydraulic limitation hypothesis." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2010. http://tel.archives-ouvertes.fr/tel-00719009.
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Les variations de transpiration totale sous contraintes hydriques, à la fois atmosphérique et édaphique, sont étudiées pour des arbres matures d'Hevea brasiliensis (clone RRIM600) dans une zone limitée en eau du Nord-Est de la Thaïlande. Les variations sont analysées et comparées entre une sécheresse transitoire en saison des pluies et la sécheresse saisonnière caractérisée par des fluctuations de la surface foliaire (sénescence foliaire, chute des feuilles and re-feuillaison) et de la croissance racinaire en profondeur. Les réponses physiologiques sont analysées dans le cadre d'un modèle hydraulique simple appelé "RER_ET0". Ce modèle est principalement basé sur une valeur critique du potentiel hydrique foliaire (ψcrit) et sur les réponses, de la conductivité hydraulique totale de l'arbre (gL) et du potentiel hydrique de base (ψpredawn), à la disponibilité en eau du sol (REW). Une estimation précise et en continue de la transpiration totale des arbres durant une année complète était une mesure clé de cette étude avec des mesures concomitantes des conditions environnementales et du potentiel hydrique foliaire (ψLeaf). Nous avons appliqué la méthode à dissipation thermique transitoire (TTD) développée par Do et Rocheteau (2002b) qui a plusieurs avantages mais n'avait pas été testée sur bois d'hévéa. La méthode TTD a été calibrée en laboratoire sur des segments de branches d'Hevea brasiliensis et de deux autres espèces (Mangifera indica and Citrus maxima). Les résultats fournissent une calibration linéaire unique indépendante des espèces étudiées (R² = 0.88, n = 276, P<0.0001). Une comparaison en plantation via un bilan hydrique du sol en saison sèche valide les ordres de grandeurs de transpiration ainsi estimés par les flux de sève. Les résultats démontrent une remarquable saturation de la transpiration au dessus d'un certain seuil d'évapotranspiration de référence (ET0), environ 2.2 mm day-1, indépendamment de la disponibilité en eau du sol (REW). Ensuite, le dessèchement du sol en saison des pluies provoque une chute marquée de la transpiration en dessous d'un seuil de 50% du REW dans l'horizon de surface du sol, ce qui correspond à ψpredawn autour de -0.45 MPa. La transpiration est réduite de 40% à REW 0.3 et 80% à REW 0.1. La valeur minimale de potentiel hydrique foliaire (ψminimum) en journée ensoleillée ne décroit pas en fonction du dessèchement du sol mais est stable autour de -1.95 MPa ce qui suggère un comportement iso-hydrique. La décroissance de la transpiration est essentiellement liée à la variation de gL. Les résultats durant la sécheresse saisonnière montrent étonnamment que les principes du modèle à limitation hydraulique tiennent malgré les variations de phénologie et de surface foliaire. De plus, les variations phénologiques ont peu influencé sur les détails des paramètres et relations du modèle. Finalement, le cadre du simple modèle hydraulique a été suffisant pour décrire correctement les principales variations de transpiration de l'arbre sous contrainte hydrique édaphique comme climatique. Un comportement iso-hydrique des arbres matures étudiés est démontré à la fois par les résultats expérimentaux et la modélisation.
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Isarangkool, Na Ayutthaya Supat. "Change of whole-tree transpiration of mature Hevea brasiliensis under soil and atmospheric droughts : analyze in intermittent and seasonal droughts under the framework of the hydraulic limitation hypothesis." Phd thesis, Clermont-Ferrand 2, 2010. http://www.theses.fr/2010CLF22044.
Full textAbstract:
Les variations de transpiration totale sous contraintes hydriques, à la fois atmosphérique et édaphique, sont étudiées pour des arbres matures d'Hevea Brasiliensis (clone RRIM600) dans une zone limitée en eau du Nord-Est de la Thaïlande. Les variations sont analysées et comparées entre une sécheresse transitoire en saisons des pluies et la sécheresse saisonière caractérisée par des fluctuations de la surface foliaire (sénescence foliaire, chute des feuilles et re-feuillaison) et de la croissance racinaire en profondeur
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Cordero, Mera Andrea Estefania. "Reservoir influences on droughts and floods characteristics in the Piedmont Region, Italy." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Find full textAbstract:
Among the consequences of global climate change, the alteration of hydrological cycles is one of the most worrisome, since it can result in an intensification of the characteristics of extreme events. In the Anthropocene era, human activities can further increase the frequency and magnitude of floods and droughts. Therefore, it is of utmost importance to analyse the influence of anthropogenic activities on the magnitude and frequency of hydrologic extremes. In the present work, Piedmont region (Italy) was taken as a case study. The work analyses 15 pairs of regulated up- and downstream catchments characterized by the presence of dam/reservoirs (hydroelectrical, irrigation and small artificial reservoirs). Following an analysis of the climate and hydrological regime of the catchments, based on the collection and spatial processing of hydro-meteorological time-series, a main general purpose has been assigned to each catchment and information on the reservoirs present in the basins were collected. Then, extreme events occurring in the last decades were identified using the threshold level approach with a constant and variable threshold for droughts, and the peak over threshold method for floods. The characteristics of the extreme events, such as duration, deficit/volume and intensity/peak were then computed. The quantification of the impact of the different dam/reservoir purpose was analysed through the paired-catchment analysis, which consists in the comparison of the drought/flood characteristics between up- and downstream catchments. The obtained results seem to indicate an overall alleviation of the severity of the drought and flood metrics downstream. It was also noticed that the magnitude of these changes is related to the dam/reservoir purpose (higher for hydroelectric purpose) and their volume. This study could be used as a first estimate of human influence (reservoirs) on hydrological extremes in Piedmont.
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Villalobos, Hitos Yéssica Montsserrat. "Shedding Light on Droughts: Light in Art Installations as an Awareness Tool." Thesis, KTH, Ljusdesign, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-280084.
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The master thesis studies the value of light art installations as a tool to raise awareness, communicate messages,inspire people and create social engagement to take action and deal with important issues. Additionally, it researchesthe lighting characteristics that have to be considered in order to create a high emotional response. Three case studieson light art installations tackling environmental issues were selected to understand the tools that makes themsuccessful. The final result of the thesis is the design proposal for a site specific light art installation to raise awarenesson droughts and its effects - following the CLUE competition 2019 guidelines - and create social engagement to fightthis major crisis. Specifically, the installation uses daylight in combination with shadows and reflections, in order toachieve the purpose of the installation. In the interest of creating a strong emotional response from the visitors,brightness, color, dynamics, contrast and direction of the perceived light were used to change the visitor’s perception ofthe space. The thesis concludes with the discussion of the evaluation of the installation to prove how effective thedesign is to achieve its purpose on raising awareness on droughts and the presence of the 7 light characteristics inorder to create an emotional response from the visitors.
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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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Konrad, Christopher P. "The frequency and extent of hydrologic disturbances in streams in the Puget Lowland, Washington /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/10187.
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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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Zink, Matthias [Verfasser]. "Soil Moisture Droughts in Germany: Retrospective Analysis, Parametric Uncertainty, and Monitoring / Matthias Zink." München : Verlag Dr. Hut, 2016. http://d-nb.info/1122524412/34.
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Nguvava, Mariam Melikizedek. "Understanding the characteristics of droughts over Eastern Africa in past and future climates." Doctoral thesis, Faculty of Science, 2020. http://hdl.handle.net/11427/32890.
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Drought poses a threat to socio-economic activities across eastern Africa and its river basins. While there are indications that global warming may continue to enhance evaporation and intensify droughts at all scales, most drought projections over eastern Africa are based on rainfall alone and are limited to meteorological droughts. The present study combines rainfall and Potential Evapotranspiration (PET) to examine the characteristics of meteorological and hydrological droughts in present and future climates at the regional and river basin scales. To accomplish that we have applied five objectives; i) Study the temporal and spatial characteristics of eastern Africa droughts modes, ii) Investigate how some atmospheric teleconnections influence the characteristics of the Africa droughts modes, iii) Examine the influence of 1.5°C and 2°C global warming levels on drought modes in eastern Africa under two future climate scenarios, RCP 4.5 and RCP8.5 iv) Assess how increases in global warming will influence drought characteristics over eastern African river basins. v) Examine the potential impacts of climate change and land use change on water availability in the Rufiji River basin (RRB), Tanzania, with an emphasis of hydrological droughts in this basin. Different types of datasets, including gridded and station observation datasets, regional climate model simulations (CORDEX: Coordinated Regional Climate Downscaling Experiment) and hydrological simulations (SWAT: Soil and Water Assessment Tool), were analysed for the study. The meteorological drought were characterised using two indices (i.e. Standardized Precipitation Evapotranspiration Index, SPEI; Standardized Precipitation Index, SPI) at 3- and 12-month scales, while the hydrological droughts were characterised using four indices (i.e. soil water index, SWI; Surface Runoff Index, RFI; Water Yield Index, WYI; and Stream Flow index, SFI). The study combined principal component analysis (PCA) with wavelet analysis to identify the spatio-temporal structure of four dominant drought modes over the region. It also used wavelet coherence to quantify the influence of four atmospheric teleconnections (i.e. El Niño Southern Oscillation, ENSO; Indian Ocean Dipole, IOD; Tropical Atlantic Dipole Index, TADI; and Quasi-Biennial Oscillation, QBO) on the drought modes. The study also projects the characteristics of future droughts over eastern Africa and its major river basins at different global warming levels (GWLs). Series of hydrological simulations were used to assess the sensitivity of future droughts to four land use change scenarios (i.e. increase in forestry, shrubs, cropland and agriculture) over the Rufiji River Basin (RRB), a prominent river basin in eastern Africa. Although eastern Africa have been documented with several drought studies, the application of a combination of PCA, Wavelet analysis, wavelet coherence and Self Organizing Maps provides more comprehensive representation of droughts in the region using SPEI/SPI derived from both models and observations The results of the study show that the four drought modes, which have their core areas over different parts of eastern Africa, account for more than 45% of drought variability in the region. All the drought modes are strongly coupled with either ENSO or IOD indices (or both); but, in addition, one of the modes is also strongly coupled with the TADI. CORDEX models give a realistic simulation of the relevant climate variables for calculating drought indices over eastern Africa and the river basins. However, the ensemble mean struggles to reproduce the spatial distribution and frequency of drought intensity in the region. The CORDEX simulations project no changes in the spatial structure of the drought modes but suggest an increase in SPEI drought intensity and frequency over the hotspots of the drought modes and elsewhere in the region. The magnitude of the increase, which varies over the drought mode hotspots, increases with increasing GWLs. The projections also show that the increase in intensity and frequency of drought can be attributed more to increased PET than to reduced precipitation. In contrast to the SPEI projection, the SPI projection shows a weak change in intensity and frequency of droughts, and the magnitude of the increase does not vary with the GWLs. Over the river basins, the SPEI projections are more robust than the SPI projections. Over the RRB, the future projections of some hydrological drought indices (i.e. RFI and SFI) follow the change in the SPEI projections, while others (i.e. SWI and WYI) follow that of SPI. Among the four land use scenarios considered, only forestry and shrubs show a substantial change in the hydrological drought indices. The results of the study thus give valuable insight into the characteristics of future droughts in eastern Africa and provide a useful guide to the effectiveness of using land cover to reduce the severity of hydrological droughts over river basins in the region. However, resolution of CORDEX dataset (50km, i.e. 0.44deg) could be among the potential limitation as it is too low to capture the influence of local-scale processes (e.g. sea breeze, mountain induced circulations) on drought over the region.
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Gore, Michelle Jacqueline. "Understanding the impacts of ENSO patterns on droughts over southern Africa using SPEEDY." Master's thesis, Faculty of Science, 2019. https://hdl.handle.net/11427/31879.
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The El Niño Southern Oscillation (ENSO) is a major driver of southern Africa droughts, but the nonlinearity of ENSO variation inhibits accurate prediction of droughts. While studies have identified multiple patterns of ENSO, most drought predictions over southern Africa are still based on only two ENSO patterns. This study examines the relationship between southern African droughts and eight ENSO patterns: four El Niño SST conditions (EN1 - EN4) and four La Niña SST conditions (LN1 - LN4). In this study we analyzed multi-forcing ensemble simulations from SPEEDY (a general circulation model from the International Centre for Theoretical Physics) and used two drought indices (SPEI: Standardized Precipitation Evapotranspiration Index; SPI: Standardized Precipitation Index) to characterize drought. The capability of SPEEDY in reproducing southern Africa climate was evaluated by comparing the historical simulations (1979- 2008) with the Climate Research Unit (CRU) observation. To obtain the influence of ENSO patterns, we forced the SPEEDY simulations with SST of each ENSO pattern, analyzed the impacts on the simulated drought indices (SPEI and SPI), and studied the atmospheric dynamics that link each ENSO pattern to southern Africa droughts. The results show that SPEEDY generally captures the temporal and spatial distribution of climate variables over southern Africa well, although with warm and wet biases across the region. However, in most cases, these results are comparable with those from more complex atmospheric models. In agreement with previous studies, the results show that El Niño SST conditions weaken the Walker circulation and cause drier conditions over parts of southern Africa, whilst La Niña SST conditions strengthen the Walker Circulation and cause wetter conditions. However, the results show that the differences in the El Niño SST conditions (EN1 - EN4) alter the circulation, thereby influencing the spatial pattern and intensity of drought over the region. For instance, while EN2 induces the most severe drought in the tropical area, EN4 produces it in the southwestern region, because the two patterns feature different characteristics of anticyclonic moisture flux over southern Africa. The same is true of the La Niña SST conditions. Although, LN1 and LN4 show wet conditions across the southern part of the region, LN1 produces drought in the northern part, while LN4 induces it along the western coast. Hence, this study shows that accounting for the differences in El Niño (or La Niña) conditions may improve drought predictions in southern Africa.
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Lawal, Shakirudeen Abimbola. "The response of southern African vegetation to droughts in past and future climates." Doctoral thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29327.
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Drought and climate change pose a threat to southern African vegetation. This study examines the response of southern African vegetation to drought in both past and future climates. Multiyear and multi-simulation datasets from three dynamic global vegetation models (DGVMs), namely, Community Land Model version 4 (CLM4), Community Land Model version 4 with Variable Infiltration Capacity hydrology (CLM4VIC), and Organising Carbon and Hydrology in Dynamic Ecosystems designed by Laboratoire des Sciences du Climat et de l’Environnement (ORCHIDEE-LSCE). These three DGVMs and the Community Earth System Model (CESM) were analyzed for the study. The DGVM simulations were forced with the reanalysis climate dataset from the National Centers for Environmental Prediction (NCEP) and the Climatic Research Unit - NCEP (CRUNCEP). The simulated climate results were evaluated with observation datasets from the Climatic Research Unit (CRU), while the simulated vegetation index (i.e. Normalized Difference Vegetation Index, NDVI) were evaluated with NDVI data from the Global Inventory Modelling and Mapping Studies (GIMMS). Meteorological droughts were analyzed at different timescales (1- to 18-month timescales), using two drought indexes: the Standardized Precipitation Evapotranspiration Index (SPEI) and the Standardized Precipitation Index (SPI). The responses of vegetation to drought were quantified by means of Pearson Correlation Analysis. The DGVMs were applied to study the sensitivity of vegetation to fire, while the CESM was used to project impact of climate change on the characteristics of southern African vegetation in the future (up to the year 2100) under the 8.5 Representative Concentration Pathway (RCP8.5) scenario, focusing on impacts at 1.5oC and 2.0oC global warming levels (GWLs). Analysis of the observed data shows that the spatial distribution of vegetation across southern Africa is more influenced by the rainfall distribution than by the temperature distribution. The observed correlation between drought index and vegetation index is higher than 0.8 over southeastern part of the region at 3-month drought timescale, and there is no difference between the spatial distribution of the correlation between the SPEI and the vegetation index, and between the SPI and the vegetation index. The three DGVMs failed to capture the response of vegetation to drought; however, the CLM4 shows the best performance while ORCHIDEELSCE fared the worst of the three. The CLM4 simulation show that fire strongly influences growth of vegetation over the summer rainfall region but it has weak influence over vegetation in the western arid zone. The CESM strongly captures the spatial patterns of precipitation and the vegetation index across southern Africa, but it overestimates the magnitudes of the vegetation index across the region, except in Namibia and Angola. The CESM also underestimates the correlation between drought indexes with vegetation, and the timescales at which the vegetation respond to droughts. The CESM projects an increase in the drought intensity as a result of an increased temperature across southern African biomes. However the increase in drought intensity is more pronounced with the SPEI than with the SPI. CESM also projects a future decrease in the vegetation index (i.e. NDVI) in the region except in the dry savanna biome. The impacts of 1.5oC GWLs on the vegetation fluxes vary throughout southern Africa, and the magnitudes of changes in the vegetation fluxes are affected by a further increase in global warming over the region. While there is a good agreement among the CESM simulations on the projected changes in vegetation fluxes across the biomes, the uncertainty in the projections is higher with 1.5oC than with 2.0oC GWL. The results of the study can be applied to mitigate the impacts of climate variability and change on southern African vegetation. Specific mitigation efforts that could be applied to reduce the impacts of droughts and climate change are watershed management, improved vegetation management, impact monitoring, environmental awareness, and remote sensing tools.
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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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Kangas, Ryan S. "Characteristics of U.S. drought and pluvials from a high-resolution dataset." abstract and full text PDF (free order & download UNR users only), 2005. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1433407.
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Foster, Nichole Michelle. "Drought evaluation using tree-ring based reconstructed streamflows for rivers in New Mexico." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2008. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Ponnamaneni, Padmaja. "Economically sustainable cattle production practices during multiple years of drought and differing price cycles." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1445044271&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Burton, C. M. "Management of the River Murray during periods of extended drought /." Title page, contents and abstract only, 1988. http://web4.library.adelaide.edu.au/theses/09ENS/09ensb974.pdf.
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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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De, la Barreda Bautista Betsabe. "Vegetation sensitivity to droughts (1982-2011) through remote sensing in the Yucatan Peninsula, Mexico." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/39822/.
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Ecosystems undergo permanent alteration and degradation as a result of the pressure exerted upon them by anthropogenic activities and natural causes. Amongst the natural causes, drought can have considerable impacts on vegetation productivity; these impacts include biomass reduction and changes in vegetation cycles, growth, and vitality. Such impacts have important implications for society, and understanding the impacts of drought in natural systems will help minimise vulnerability to it. The Yucatan Peninsula is a vulnerable area in climate change scenarios, where increased intensity and frequency of droughts is already occurring. This thesis aims to analyse how droughts impact upon vegetation on the Yucatan Peninsula, Mexico using both remotely sensed data (in particular the Advanced Very High Resolution Radiometer – AVHRR - data) and meteorological data (in situ precipitation data). Three major elements are addressed: (1) spatial and temporal precipitation variability, and the occurrence of droughts during the period 1980-2011; (2) vegetation productivity trends, focusing on the persistence and resilience of the different vegetation types present across the Yucatan Peninsula using remotely sensed data sets, specifically, the Normalised Difference Vegetation Index (NDVI) from the National Oceanic and Atmosphere Administration Advanced Very High Resolution Radiometer (NOAA-AVHRR) as a proxy for productivity in the period 1982 to 2011; and (3) the relationship between vegetation productivity and rainfall and the lack of it (i.e. droughts) at a more detailed temporal scale (monthly) with two vegetation indices (NDVI from AVHRR and MTCI from the MEdium Resolution Imaging Spectrometer (MERIS)). The main findings indicate that precipitation in the area follows a gradient from north to south which is linked to vegetation types in the area, from deciduous forest to evergreen forest. NDVI trends in the Yucatan Peninsula are generally stable during the period 1980-2011; however, negative trends are persistent in areas where human impacts and intensive agriculture are present. Analysis of resilience also shows that deciduous forest and grasslands are much less resilient to disturbance and have a longer recovery period compared to other vegetation types. Per-pixel regression analysis between precipitation and vegetation productivity shows high explained variances between NDVI and rainfall with a time-lag of 1 and 2 months and tropical dry forest is the biome most affected by droughts. These results are valuable for decreasing the vulnerability of the Yucatan Peninsula and they could be used for increasing the understanding of the area and therefore go further in the creation of warning and management programmes.
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Mason, Nicole Marie. "A test of the new variant famine hypothesis panel survey evidence from Zambia /." Diss., Connect to online resource - MSU authorized users, 2008.
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Coats, Lamar S. "The Influence of Tropical Cyclones on Droughts and Warm Season Precipitation in Tennessee and Kentucky." TopSCHOLAR®, 2016. http://digitalcommons.wku.edu/theses/1567.
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The Southeast United States during summer and fall is often affected by droughts and tropical cyclones. Both phenomena rank among the most expensive of natural hazards, although droughts are not as feared by the public as hurricanes. When a tropical cyclone causes a pendulum swing from drought to wet conditions, it is known as a “drought-busting tropical cyclone.” The majority of the research related to drought busting tropical cyclones investigates only the storms during their tropical cyclone phase, which covers the southeastern states that have boundaries adjacent to the Atlantic Ocean. An unanswered question from this literature is whether or not these findings apply to the interior southeastern states that have no ocean boundaries, where there is an increase in the probability of a drought-busting tropical cyclone transitioning to an extra-tropical cyclone. This thesis research attempts to determine the impact of drought-busting cyclones on the states of Kentucky and Tennessee. Research findings in this thesis revealed that droughts occur more frequently in the eastern climate divisions of the study area, 2-3 tropical cyclones affect the study area each year, and 6% of warm-season precipitation comes from tropical cyclones or their remnants. Chi-Square analysis and Kruskal-Wallis tests suggest that the Atlantic Multidecadal Oscillation (AMO) has statistically significant relationships with drought frequency, tropical cyclone precipitation, and extra-tropical cyclone precipitation in several climate divisions. While the literature argues that drought-busting tropical cyclones are common in coastal locations, they were found to be rare in Kentucky and Tennessee.
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Meque, Arlindo Oliva. "Investigating the link between southern African droughts and global atmospheric teleconnections using regional climate models." Doctoral thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/16686.
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Includes bibliographical referencesDrought is one of the natural hazards that threaten the economy of many nations, especially in Southern Africa, where many socio-economic activities depend on rain-fed agriculture. This study evaluates the capability of Regional Climate Models (RCMs) in simulating the Southern African droughts. It uses the Standardized Precipitation-Evapotranspiration Index (SPEI, computed using rainfall and temperature data) to identify 3-month droughts over Southern Africa, and compares the observed and simulated drought patterns. The observation data are from the Climate Research Unit (CRU), while the simulation data are from 10 RCMs (ARPEGE, CCLM, HIRHAM, RACMO, REMO, PRECIS, RegCM3, RCA, WRF, and CRCM) that participated in the Regional Climate Downscaling Experiment (CORDEX) project. The study also categorizes drought patterns over Southern Africa, examines the persistence and transition of these patterns, and investigates the roles of atmospheric teleconnections on the drought patterns. The results show that the drought patterns can occur in any season, but they have preference for seasons. Some droughts patterns may persist up to three seasons, while others are transient. Only about 20% of the droughts patterns are induced solely by El Niño Southern Oscillation (ENSO), other drought patterns are caused by complex interactions among the atmospheric teleconnections. The study also reveals that the Southern Africa drought pattern is generally shifting from a wet condition to a dry condition, and that the shifting can only be captured with a drought monitoring index that accounts for temperature influence on drought. Only few CORDEX RCMs simulate the Southern African droughts as observed. In this regard, the ARPEGE model shows the best simulation. The best performance may be because the stretching capability of ARPEGE helps the model to eliminate boundary condition problems, which are present in other RCMs. In ARPEGE simulations, the stretching capability would allow a better interaction between large and small scale features, and may lead to a better representation of the rain producing systems in Southern Africa. The results of the study may be applied to improve monitoring and prediction of regionally-extensive drought over Southern Africa, and to reduce the socio-economic impacts of drought in the region.
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Hassan, Rasha. "A science-policy assessment of the effect of severe droughts in Syria: A quasi-Bayesian analysis." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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The management of prolonged droughts as an extreme event with low probability in Syria is challenging and different from developed countries. Syria is particularly vulnerable to severe drought events due to its complicated characteristics including water scarcity, geographical location, population size, and continuing war conditions. These facts emphasize the urgency to act before a drought occurs.
The study of the available literature about this topic showed the imperfect characteristics of the relevant knowledge and information. They are heterogeneous, scarce, and uncertainty-laden. This situation is challenging and unreliable for policymakers to act and quantify drought risk mainly when uncertainty arises from different sources and cannot be decreased.
Thus, a systematic and causal approach that uses a Quasi-Bayesian probabilistic method is proposed to provide drought risk assessment that can be sufficient for managing severed drought in the conditions that are prevalent for Syria. This approach is a decision-theoretic, not data-driven (i.e., experimental). The Factor Trees Model, FTM, is created based on the drought distinguishing features and its linkages to people’s lives in Syria. Three primary factors are suggested: the recurrence of drought events, area characteristics, and human behavior. Then, the Quasi-Bayesian Method is used in performing a simple analysis to assess the quality and reliability of two reports based on the FTM factors. Using our approach helps to categorize each report and compare reports, and update the flow of information adaptively to new scientific evidence. Although this approach has advantages and limitations, it is a valuable tool in situations of vague, unreliable, and limited information and knowledge.
The need for further research is essential to evolve this approach due to the complexity of the Syrian context because the method should decrease the uncertainty in each stream of knowledge to better inform policymakers.
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Parsons, Katherine. "Not all droughts are equal: understanding the climate drivers of wind erosion (ENSO, SAM and IOD)." Thesis, Griffith University, 2017. http://hdl.handle.net/10072/373953.
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Wind erosion is recognised as an important issue globally. It is of importance in Australia due to a large proportion of the continent being classed as arid to semi-arid. With increases in land use and projected increases in the frequency and intensity of drought periods in Australia, wind erosion may be seen to increase, intensify and expand across the continent. Additionally, increases in the severity of annual to inter-annual climate systems (such as the El Niño Southern Oscillation (ENSO), the Southern Annual Mode (SAM), the Indian Ocean Dipole (IOD)) and even in overarching decadal to inter-decadal climate systems (such as the Interdecadal Pacific Oscillation (IPO) and the Pacific Decadal Oscillation (PDO)) will result in the spatial and temporal impacts of wind erosion being altered over time. Variations in drought and climate systems are recognised to affect wind erosion in Australia due to their influences on precipitation and erosive wind systems.
Literature in the field of drought, wind erosion and climate systems was reviewed with respect to framing the need for this dissertation. It was identified that although a detailed understanding of drought has been developed over time (including definitions, impacts and influences) there are still challenges associated with the lack of uniform definition and with measures of severity, scale and overall prediction. Few wind erosion studies have focused on the impact that drought may have (and its flow-on effects to other wind erosion variables such as vegetation), particularly with respect to changes in response to climate. Climate systems research presents another layer of complexity to measuring or predicting wind erosion in Australia.
This dissertation explores the role of drought and climate systems in wind erosion in eastern Australia (over the past 100 years), comparing a calculation of the potential for wind erosion with actual wind erosion (AWE) measures. It selects and adapts a drought index suitable for use in wind erosion studies and estimates the wind erosion potential (WEP) of eight drought periods, incorporating measures of soil erodibility and wind erosivity. It also evaluates why actual wind erosion rates (according to three different measures) differ to results produced by the WEP and examines how climate systems (the ENSO, SAM and IOD) and synoptic-scale systems influence wind erosion during the drought periods.
Two drought indices (rainfall deciles (RD) and the Standardized Precipitation Index (SPI)) were assessed according to seven criteria developed to evaluate the favourability of indices for use in wind erosion studies. The SPI was selected as the most favourable due to its ability to identify the start and end dates of drought, provide measures of drought intensity, magnitude and severity and best capture wind erosion activity. The SPI was adapted and enhanced for the calculation of WEP using established factors of drought, erodibility (vegetation cover) and erosivity (wind speed) and applied to historical data (over 100 years from the consolidation of 63 observer stations into 22 stations in eastern Australia. Differences in results were evident for northeastern Australia (NEA) and southeastern Australia (SEA), reflecting varying short and longer term climatic influences. At a localised level wind severity, vegetative cover types and geomorphological features were able to explain differences. Specific climate systems phases (negative ENSO, negative SAM and positive IOD) occurring drought periods were found to favour wind erosion activity (both in NEA and SEA). A combination lock of climate system phase and wind erosion risk was developed to provide a conceptual understanding of the influence of climate systems on wind erosion during drought periods in Australia. This conceptual approach is unique to this dissertation, constituting an original innovation in the field of wind erosion research during drought and climate system studies in general. Combinations of climate system phases and associated wind erosion risk were presented for eight combinatoric scenarios, with highest wind erosion risk associated with negative ENSO, negative SAM and positive IOD. These combinations were demonstrated to have differing impacts according to location on the Australian continent due to differing synoptic-scale system dominance (trough systems in the north and cold fronts in the south).
This dissertation has confirmed the important role that climate systems have on wind erosion during drought periods in eastern Australia. Its results have new implications for research in the field of wind erosion. It demonstrates a method of measuring drought from a wind erosion perspective and develops a way of both estimating wind erosion potential risk and investigating wind erosion activity from the lens of climate systems. The combination lock approach to climate systems and wind erosion during drought periods provides a conceptual advance in the climatological and meteorological understanding of wind erosion activity (spatially and temporally). Furthermore, at a time when the future impacts of drought and climate systems are predicted to intensify in severity and spatial scale, this research could provide a way for aeolian geomorphologists and land managers to predict the risk of wind erosion occurrence.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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FARIAS, André Aires de. "Caracterização e análise das secas na sub-bacia hidrográfica do Rio Taperoá e avaliação dos impactos e ações de convivência com a seca de 2012-2014 no município de Taperoá – PB." Universidade Federal de Campina Grande, 2016. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/985.
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Objetivou-se identificar e analisar os períodos de secas na sub-bacia hidrográfica do Rio Taperoá (SBHRT) e os impactos sociais, econômicos e ambientais e ações de convivência com a seca de 2012-2014 no município de Taperoá - PB. Dados pluviométricos, série 19632014, foram utilizados para analisar o regime de precipitação da sub-bacia; e a severidade dos anos secos, por meio do Índice padronizado de precipitação. A identificação dos impactos foi realizada utilizando-se o método de listagem descritiva check-list, questionários, dados bibliográficos e documentais. Para analisar as variáveis socioeconômicas e as ações de convivência foram utilizados os mesmos materiais dos impactos, exceto o check-list. O período chuvoso dos municípios da sub-bacia ocorre de janeiro a maio, precipitações menores do que a média nesses meses causaram graves impactos. Verificou-se que a maioria das secas que ocorreram na SBHRT se enquadram na categoria moderada, seguido por severa e extrema. A SBHRT foi atingida por secas severas e extremas durante todas as décadas analisadas, no entanto, o maior número delas ocorreu nas décadas de 1980, 1990, 2000 e 2010. A seca mais grave foi a de 1998-2000, seguido pela de 1979-1985. A seca de 20122014 não foi a mais grave porque a precipitação foi acima da ocorrida no período de 19982000 e 1979-1985, houve também maior investimento em ações de convivência com as secas e programas sociais implantados pelos governos. Os impactos sociais, econômicos e ambientais da seca de 2012-2014 no município de Taperoá-PB foram: problemas de saúde relativos à baixa disponibilidade hídrica, desigualdade na distribuição de recursos durante a seca, desgaste mental, reduções na alimentação da população, conflitos entre usuários de água, aumento da pobreza, migrações populacionais, redução da pecuária e da produção de culturas, aumento do desemprego, elevação dos custos para transportar água, indisponibilidade de alimentos para animais, perturbação dos ciclos de reprodução, redução de recreação e turismo, prejuízos à flora, à fauna e às espécies piscícolas, e redução da qualidade da água. Os impactos continuaram porque faltou recursos financeiros para implantar programas e as políticas públicas de convivência não foram efetivas, só aparecendo com maior intensidade quando a região estava prejudicada pela seca. Para redução dos impactos é necessário aumentar o número de cisternas, principalmente a calçadão. É necessário também perfurar poços e construir açudes, além de fazer manutenção nos que estejam com capacidade reduzida ou desativados, construir barragens subterrâneas e tanques naturais, terminar e colocar em funcionamento a Transposição do Rio São Francisco, incentivar a gestão dos recursos hídricos, criar programas que visem o fortalecimento da agricultura familiar, incentivando a fenação, silagem, meliponicultura, apicultura, criação de animais e plantas adaptados à região, dentre muitos outros.
This study aimed to identify and analyze the periods of droughts in sub-basin hydrographic of the Taperoá River (SBHTR) and the social, economic and environmental impacts and living actions with drought from 2012-2014 in the municipality of Taperoá - PB. Rainfall data, serie 1963-2014, were used to analyze the sub-basin rainfall regime; and the severity of the dry years, through the Standardized Precipitation Index. The identification of social, economic and environmental impacts was performed using the method of descriptive listing check-list, questionnaires, bibliographic and documentary data. To analyze the socioeconomic variables and of actions of living together were used same materials of the impacts, except the checklist. The rainy period in the municipalities of the sub-basin occurs from january to may, precipitations lower than average in these months caused severe impacts. It was found that most of droughts in SBHRT occurred into the category moderate, following by severe and extreme. The SBHRT was hit by severe and extreme dried for all analyzed decades, however, as many of them occurred in the decades of 1980, 1990, 2000 and 2010. The most severe drought was the from 1998-2000, followed by 1979-1985. The drought of 2012-2014 was not the more serious because the precipitation was above occurred in 1998-2000 and 1979-1985 period, there was also greater investment in coexistence actions with droughts and social programs implemented by governments. The social, economic and environmental impacts of the drought of 2012-2014 in the municipality of Taperoá-PB were: health problems of low flow, unequal distribution of resources during the drought, mental strain, reductions in food supply, conflicts water users, increasing poverty, population migration, reduction of livestock and crop production, rising unemployment, higher costs for transporting water, unavailability of feed, disruption of reproductive cycles, reduction of recreation and tourism, losses in flora, fauna and fish species, and reduced water quality. The impacts continued because they lack financial resources to implement programs and public coexistence policies were not effective, only appearing with greater intensity when the region was hampered by drought. To reduce the impacts is to increase the number of cisterns, especially the boardwalk. You also need to drill wells and build dams, in addition to maintenance on that are with reduced or deactivated capacity, building underground dams and natural ponds, finished and put into operation the Transposition of the São Francisco River, encourage the management of water resources, create programs aimed at strengthening family farming, encouraging haymaking, silage, beekeeping, meliponiculture, husbandry of animals and plants adapted to the region, among many others.