Groundwater Vulnerability Assessment And Prediction In Zhaozhou County Based On DRASTIC Mode

With Zhaozhou County,Heilongjiang Province as the study area,based on DRASTIC model and the analysis of regional hydrogeological conditions,the factors affecting groundwater vulnerability in the study area are re-selected.Taking groundwater depth,aquifer net recharge,aquifer medium type,soil medium type,topographic slope,land use type and groundwater carrying capacity as the main data as the evaluation index,re-delimit the evaluation index score value,and optimize the weight of evaluation index by AHP.Construct AHP-DRASTL-CRD groundwater vulnerability assessment system.According to the groundwater vulnerability assessment index size,Zhaozhou County was divided into groundwater vulnerability zones by ARCGIS,and the main variable indexes affecting groundwater vulnerability were predicted to explore the evolution characteristics and trends of groundwater vulnerability in the study area in the next 30 years,in order to provide theoretical basis and technical support for the prevention and control of groundwater pollution in the region.The following conclusions were drawn in this paper:(1)The assessment results of groundwater vulnerability in Zhaozhou County based on DRASTL-CRD model show that the groundwater vulnerability level in the study area decreases continuously from south to north,with low vulnerability areas concentrated in the north of Zhaozhou County and high vulnerability areas concentrated in the south of Zhaozhou County.The medium vulnerability area is the main type of groundwater vulnerability in the study area,with an area of 750.23 km~2accounting for32.6%of the total area,which is the most widely distributed and the largest area.(2)Based on the sensitivity analysis,the comprehensive correlation index of groundwater carrying capacity is the most sensitive index,followed by land use type,and aquifer medium is the least sensitive index,which basically conforms to the order of the weight value of DRASTL-CRD model evaluation index.It shows that the evaluation system of DRASTL-CRD is reasonable and reliable when considering the influence factors such as human activities.(3)Forecast the atmospheric precipitation in the study area in the next 30 years through the long and short term memory network,forecast the net recharge of aquifer and groundwater depth under the conditions of two extreme typical climate years,combined with the established groundwater vulnerability assessment system prediction:With the increase of rainfall,it will directly lead to the increase of aquifer net recharge and the decrease of groundwater depth,which will make it difficult for pollutants to completely and fully degrade in soil and aeration zone,and the groundwater vulnerability will face the possibility of increasing areas with high vulnerability.