The Quantitative Evaluation Of Water Security In Zhangye City

Water security always includes various hazards resulting from water along with the social and economic development, such as flood, water shortage and pollution, etc. Large-scale degradation of water quality and water shortage in arid districts have become the most prominent water issues in the world since 1970s, which are getting more and more incisive with the time day by day. Its emergence has been threatening humanity's survival. So far, much attention has been paid to the water security issue worldwide. Water is one of the most important factors in arid and half arid districts. At present, a sire of water security issues caused from water shortage have been severely restricting the social and economic sustainable development. Therefore, this thesis, focusing on Zhangye city in the middle stream of Heihe River, using Multi-objective and multi-level fuzzy optimization model, is to evaluate the water security condition quantitatively, aiming at offering certain theoretical guidance for rational and effective water utilization in zhangye, so that the ecological environment and social economy of the region develops harmoniously. The thesis divides into six parts altogether.The first part introduces the study background, sketches the current frontal studies of water security and the hot problems domestic and abroad, and describes the purpose and significance, as well as the research theory and method used in the study.The second part analyzes the water security condition and the main water security issues of Zhangye city, such as water shortage, ecological environment degeneration, food safeguard question and rural drinking water safety issue, based on summing up the natural environment and social economic situation in Zhangye city, and analyzes the main impact factors of the water security of Zhangye city from natural and manmade aspects.The third part selects the specific indexes according to the characteristics of local water security condition and the collection of date, on the basis of existing index system of evaluating regional water security, and establishes the index system of evaluating water security of Zhangye city.The fourth part, makes a quantitative evaluation about the water security condition of the five years after 1990 and the six counties of Zhangye city, using the multi-objective and multi-level fuzzy optimization model, and does a comparative analysis of the evaluation results. The results are as follows: (1) the water security issues have been existing for a long time in Zhangye city, and the water security condition is deteriorating and getting hard severe as the time passed since 1990s; (2) the water security issues of the six counties of Zhangye city are quite serious, Sunan is comparative superiority among them, following is Minle, Ganzhou, Shandan, Gaotai, Linze. The water security conditions of the. six counties are obviously differences, such as irrigation areas along the mountains are better than the areas along the rivers, and the upstream regions are better than the downstream regions of mainstream of Heihe River. The result of evaluation is consistent with the realities, so multi-objective and multi-level fuzzy optimization model could be used to evaluate water security of Zhangye city, and has practical applicable value and prospects in the research of water security evaluation.The fifth part, on the basis of the evaluation result, constructive measures for the water security of Zhangye city is proposed, from five aspects such as contradictions in the supply and demand of water resources, protection of the ecological environment, ensuring food security, increasing the ability to fight natural disasters and protecting rural drinking water safety.The last part raises the problems of further research and thought based on the thesis after summarizing the full thesis.