Evaluation Of Groundwater Pamping Risk In The Plain Area Of Xi'an City

Xi'an is western China's economic and cultural center, it is the capital city of Shanxi Province, As the water resources,total and surface are relatively scarce, groundwater has been the main source of water in Xi'an.The economic and the ecological environment rely on groundwater a lot in Xi'an city a long period of time, in recent years, been invoked as a result of the Hei river water,the proportion of groundwater has decreased significantly, but still account for a large proportion of the water utilization,and the exploitation of huge,2005,it accounts for 66.13% in the total water supply.The pumping risk of groundwater resources is closely with conomic and the ecological environment,with the development and utilization of groundwater is not unreasonable, there has appeared a series of environmental geological, in order to protect the groundwater resources and the environment effectively, and achieve the development and utilization of groundwater resources Sustainable ,it is necessary and important to analyse and evaluate the pumping risk in groundwater resources effectively and correctly.In this paper, based on a large number of research results home and abroad,we summarized the problems of the risk in groundwater development and utilization.we have analyzed the pumping regime of groundwater resources by computational methods of probabilitical statistics. we have assessed the amount of groundwater resources total and utilizable in plain area of Xi'an by waterbalance method. Through summarizing the status quo and trends of groundwater development and utilization,we build a indexes system of the groundwater pumping risk evaluation,and evaluated the risk by Catastrophe Theory.The main results as follows:①Based on analyzing the natural and geohvdrologic condition, the whole plain area of Xi'an were divided into alluvial-proluvial plain, proluvial fan and Loess mound three groups, the quantity of groundwater resources is 121643×10~4m~3, and the multi-year mean quantity of utilizable groundwater is 116140×10~4m~3 in plain area of Xi'an.②we analyzed the pumping regime of groundwater resources in Xi'an city from 1995 to 2005, the results showed that the exploitation of groundwater has decreased year by year since 1995,but it Still overpumping in general in 2005,the pumping degree reached 100.44%,among them,Yanliang District had seriously overpumping,the pumping degree reached 303.69%.③From the basic conception of risk,we had used computational methods to compute the risk probability and extent of damage, The results show that the risk probability is 0.75 and the extent of damage is 0.097.④The risk evaluation indexes system for groundwater development and utilization of Xi'an was built up, the evaluation result showed that the synthesis risk value for groundwater development in Xi'an is 0.70,belongs to middle risk area, Zhouzhi county was designated as mild risk area, Hu county was designated as punily risk area, other districts are all designated as mild risk area. the synthesis risk value of the Center City area is the highest,it reached 0.79. Final, we made a few suggestions on how to exploit groundwater correctly and protect it.