Evaluation Of Groundwater Vulnerability In Mianzhu Plain Area

Groundwater is the main source of water supply in Mianzhu.With the rapid development of industry,agriculture and urban construction,groundwater is facing severe pollution pressure.It is urgent to carry out the evaluation of groundwater vulnerability in Mianzhu for the rational development and protection of groundwater.This paper summarizes the basic concepts of groundwater vulnerability and the current situation of research methods.The groundwater vulnerability assessment in Mianzhu Plain is the main research content,and the groundwater in Mianzhu Plain is the research object.Based on the geography and geological background of the study area,the DRASTIC model was used to evaluate the inherent vulnerability of groundwater and the inherent vulnerability map was drawn.According to the actual situation of the study area,the influence of human activities was considered,and the evaluation index system of groundwater vulnerability based on human activities was constructed.The weight of index was calculated by using analytic hierarchy process(AHP),and the groundwater vulnerability of the study area was evaluated on GIS.And puts forward the suggestions on rational utilization and protection of groundwater resources.The main results are as follows:(1)The DRASTIC model was used to evaluate the inherent vulnerability of the study area.The results show that the area with high vulnerability is the largest,mainly distributed in the area of alluvial fan.River floodplains and terrestrial terrestrial areas have the highest inherent vulnerability.(2)In view of the actual situation of the study area,the evaluation index system is improved,and the influence of human activities on the vulnerability of groundwater is taken into account,and the influence index of water fragility is increased.The evaluation index system of groundwater vulnerability based on human activities was constructed by selecting eleven indexes of the depth of water-table,the net recharge,the soilmedia,the topography,the impact of the vadose,the tydraulic conductivity of the aquifer,the aquifer thickness,the water yield property,the specific yield,the groundwater quality and the groundwater exploitation intensity.(3)The weight of the evaluation index was recalculated by the analytic hierarchy process(AHP),and the groundwater vulnerability based on human activities was evaluated by using GIS to evaluate the single index evaluation results.The results show that river floodplain and the area of high groundwater exploitation is the most vulnerable.(4)Combining the inherent vulnerability and the vulnerability assessment based on the impact of human activities,it shows that the groundwater vulnerability in Mianzhu is generally high,which is the highest in the river basin area and the pollution concentration area,and is fragile from the top of the alluvial fan to the middle and lower areas The overall distribution of the population from low to high,groundwater recharge area to the runoff area to the excretion zone from low to high vulnerability.The evaluation results are consistent with the spatial distribution of the geography and geological conditions in Mianzhu plain area.After adding human factors,the impact of human activities on vulnerability is better.The evaluation results can objectively reflect the characteristics of groundwater fragility in Mianzhu.