The Vulnerability Assessment Research Of Phreatic Groundwater In Hulunbeier High Plain

Hulunbeier high plain is located in east of the Mongolian plateau prairie region. The total amount of groundwater resources in hulunbeier administrative region is about 7.5 billion m3 and the number is about 2900 m3 per capita in 2012. Although the groundwater resources per capita is relatively abundant, the environment is fragile and the groundwater is vulnerable to be polluted since developing industry and agriculture, unreasonable management and development of groundwater, increase discharge of chemical fertilizers, pesticides, living rubbish and industrial sewage. Therefore, it can provide a scientific basis for the protection and sustainable development and utilization of groundwater resources to evaluate the groundwater vulnerability and strengthen the water function regionalization.The thesis is based on the work of science and technology special project "groundwater vulnerability evaluation guideline research(2012FY130400)" of water resources research institute in China Institute of Water Resources and Hydropower Research. According to the hydrogeological conditions and the actual situation of the acquired data, we selected these seven evaluation indexes which affected the phreatic groundwater vulnerability such as depth of groundwater level, net recharge, aquifer media, soil media type, aquifer water yield property, land use type and groundwater exploitation intensity of, besides. The most widely applied DRASTIC evaluation model in the parameter system is improved, inherent vulnerability DRASC evaluation model and special vulnerability DRASCLM evaluation model are established in this thesis.Based on the research achievements of domestic and foreign scholars on groundwater vulnerability assessment, hierarchy and assignment of the evaluation index are accomplished, besides, the analytic hierarchy process(AHP) is used to determine the index weight value. Combined with spatial data management and analysis functions of Arc GIS10.0 platform, the single index partition diagram and inherent vulnerability and special vulnerability zoning maps in the study area were established finally in this study, Through comparison and analysis, the vulnerability assessment of phreatic groundwater in hulunbeier high plain is studied in this thesis.The evaluation results show that, the phreatic groundwater vulnerability has a low level overall and groundwater antifouling performance is good. The areas with relatively high and high vulnerability are mainly distributed in northeast parts of the plain, some east parts of manzhouli town, the middle and lower reaches area of Hailaer and Yimin river. The distribution area is 6900 km2 and it is only 18.55% of the total study area. The land use type and groundwater exploitation intensity of human activity factors affect more obviously upon the phreatic groundwater vulnerability in the study area. The validation result of the water quality reflects that the high nitrate density areas are corresponding to the high phreatic groundwater vulnerability areas, and the special phreatic groundwater vulnerability is also correspondence well with the actual characteristics of partition in the study area. Through the analysis of sensitivity about evaluation indexes, it shows that the depth of groundwater level is the most important impact factor on phreatic groundwater vulnerability, groundwater exploitation intensity and land use type are secondly important factors on groundwater vulnerability. There are no relatively low sensitive evaluation indexes and the index selection is relatively reasonable. Finally, the groundwater resources protection and planning advices and pollution control countermeasures about the study area is put forward in this study.