Study On The Karst Groundwater Vulnerability Evaluation Of Xin'an Spring Area

As the main water resources for industrial and agricultural use of Changzhi, karst water of Xin'an spring area supported the sustainable development of social economy of Changzhi effectively. However, with the rapid development of regional economy and the accelerated process of urbanization, the demand for water resources is gradually increasing, water shortage has emerged. The shortage of karst water resources in Changzhi is increasingly prominent, therefore, how to develop and utilize the karst water of Xin'an spring area reasonably has become the main water problem in Changzhi. Taking karst groundwater of Xin'an Spring area as the research object, its vulnerability was evaluated from two aspects, water quality and quantity, in order to provide technical support for the exploitation and protection of karst water of Xin'an spring area.In this paper, through the analysis of groundwater vulnerability assessment results at home and abroad, firstly, based on overlay and index methods, according to the construction method of DRASTIC evaluation model, combined with the geological conditions and hydrogeological conditions of Xin'an spring area, and the development and utilization of karst water,7 indexes including depth to groundwater(D),recharge of infiltration(R),water abundance of aquifer(A),soil media(S),topography(T),overlying layer(O),land use type(L) were selected to establish the quality vulnerability evaluation index system and 4 indexes including recharge of infiltration(R), water abundance of aquifer(A),aquifer thickness(T),exploitation coefficient(E) were selected to establish the quantity vulnerability evaluation index system, the weight of each index was calculated using fuzzy analytical hierarchy process and grey correlation analysis method, the quality vulnerability evaluation model(DRASTOL model) and quantity vulnerability evaluation model(RATE model) of karst groundwater of Xin'an spring area were constructed to evaluate the vulnerability of karst groundwater of Xin'an spring area.Secondly, based on the results of vulnerability assessment, water quality and water quantity protection zones are divided, and the corresponding protection measures are proposed.The results of the study show that:?the general trend of water quality vulnerability of Xin'an Spring area is low in the west and high in the east, high vulnerability area, relatively high area, medium area, relatively low and low area respectively account for 2.4%, 18.4%, 14%, 8.6%, 56.5%, in the whole spring area. The high vulnerability area are mainly distributed in the wellspring area, leakage rivers and part bare karst area. ?The general trend of water quantity vulnerability of Xin'an spring area is high in the central and west and low in the east, high vulnerability area, relatively high area, medium area, relatively low account for 57.1%,19.8%,7.8%,15.3% respectively, in the whole spring area. High vulnerability area is located in the runoff static area, in the middle west of the spring area, the function of water resources is weak and the value of development and utilization is low, the area is 5672km2, accounted for 51.8% of the whole spring area. Therefore, in the high vulnerability area, the real area which is easily influenced by human activities accounts for about 8.7% of Xin'an spring area.?According to the evaluation results of water quality and water quantity, the spring area is divided into 4 types: key reserve, sub key reserve, general reserve, nature reserve. The water quality key reserve are mainly distributed in wellspring area which is located in the junction of Licheng, Lucheng and Pingshun, and Huangnian-Wuyang river seepage segment, in these regions, the development of new karst water and new land use of non water resources protection project and waste stacking should be prohibited; the water quality sub key reserve are mainly distributed in Zhangzi, east Tunliu, in these regions, the discharge of domestic sewage and industrial wastewater should be controlled to achieve standard discharge, industrial and mining enterprises with large polluting shoule be shut down or relocation. The water quantity key reserve are mainly distributed in urban and suburban of Changzhi, Lucheng, Changzhi County, in these regions, the scale of exploitation of karst well and depressurization exploitation of coal mine should be strictly controlled; The water quantity sub key reserve are mainly distributed in Zhangzi, east and southeast Xiangyuan, in these regions, the new karst wells and the coal mining with pressure should be restricted. In addition, strengthening the construction of water conservation projects and the real-time monitoring of groundwater quality and quantity to ensure the sustainable utilization of karst water of Xin'an spring area.