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University of Guelph (2015)

Examination of Water Stress in Dryland Regions : Causalities, Risks, and Strategies

Chen, Zhang

Titre : Examination of Water Stress in Dryland Regions : Causalities, Risks, and Strategies

Auteur : Chen, Zhang

Université de soutenance : University of Guelph

Grade : Doctor of Philosophy (PhD) 2015

Résumé
Water scarcity is increasingly of concern over the past decades. This research focuses on analyzing water stress in various scenarios associated with changes in climate and human influences, providing a sequenced methodology in identifying strategies in response. Long-term changes in climate are projected using the output data from the General Circulation Models. The projections are utilized to estimate the impacts of climate change on crop water requirements and irrigation water needs. A virtual water methodology is developed to identify crops which would be more appropriate as imports rather than producing them locally. Cropping patterns are investigated through a fuzzy linear optimization model. The optimization aims to attain “acceptable levels” through adjustments in cropping patterns incorporating virtual water transfers. To prevent the trend towards desertification in dryland regions, an approach is established for assessing the potential risks of desertification base on soil erosion, using Gansu Province in China as a case study. The effects of climate change and population growth on water stress are compared using the Aridity Index and Falkenmark Water Stress Indicator for Zambezi River Basin in Southern Africa. Results indicate that the drier climate in the future may lead to the increases in both crop water requirements and irrigation water needs. Current cropping patterns in Gansu are causing extreme stress on water resources. Therefore, crops which use large amount of water while contain low economic values for the water used are suggested to be imported rather than to be grown locally. A considerable amount of irrigation water can be saved applying the optimization model and virtual water transfers. In addition to water stress, intensified land use and population density can also aggravate the degrees of desertification. However, improving vegetative cover and cropping methods can significantly reduce the areas experiencing severe desertification. The results also indicate that the changes in climate will extend dry seasons in Zambezi River Basin for approximately one month longer and will lead to less water availability. Moreover, population growth is estimated to be twice the impact on water stress compared with climate change

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Page publiée le 18 novembre 2015, mise à jour le 27 août 2019