Vulnerability Assessment Of Karst Groundwater In Huaxi River Basin Based On GIS And ANN Methods

The karst groundwater system in the Huaxi River Basin is very complex,and its unique karst hydrogeological conditions make the groundwater easily polluted.Therefore,it is imperative to carry out the research on karst groundwater vulnerability evaluation.Based on the investigation of the hydrogeological conditions of the karst environment in the Huaxi River Basin,the vulnerability of the karst groundwater in the study area was evaluated by the coupling method of GIS and ANN.Mainly achieved the following results:(1)By analyzing and summarizing the present situation and development of groundwater vulnerability,a comprehensive evaluation method of GIS and ANN coupling is adopted.(2)According to the actual situation and related data of Huaxi River Basin,referring to DRASTIC evaluation index system and according to the previous research on the influencing factors of karst groundwater.Selected terrain slope,the type of aquifer,atmospheric precipitation,the thickness of the unsaturated zone,unsaturated zone types,karst development degree,karst landform,average permeability coefficient,land use type and pollution source type as an evaluation index,and establish the evaluation index system for the study area(3)Each evaluation factor is processed by Arc GIS to generate the distribution of the evaluation factors and the thematic map.(4)Select a three-layer BP neural network model in artificial neural networks.The weight index of 10 indicators for karst groundwater vulnerability was calculated by training the sample data of the evaluation index.The weight coefficients are 0.0626,0.116,0.0955,0.0952,0.1305,0.1066,0.0933,0.1174,0.0748,0.1081.(5)The evaluation model of karst groundwater vulnerability based on GIS and ANN is established.By calculating the vulnerability index,the study is divided into five regions: highest,higher,medium,lower and lowst vulnerability.Each area accounted for 9.76%,24.16%,28.78%,17.15% and 20.15% of the total area of the study area.The evaluation model is consistent with the actual situation,and the corresponding groundwater exploitation and protection suggestions are put forward for each vulnerable partition.The evaluation results of karst groundwater vulnerability in Huaxi River Basin can provide technical reference for the construction of towns,transportation and water conservancy in karst area.