Comparative Study On Evaluation Methods Of Groundwater Vulnerability In Inland Arid Area

At present,the evaluation of groundwater vulnerability in northwest China's arid areas is less than that in other areas.This paper used three groundwater vulnerability assessment models in arid areas?DRAV model,VLDA model,VDEAL model?which have been performed and one classic model-DRASTIC model for comparative study on evaluation methods of groundwater vulnerability.In this study,Oasis City-Shihezi City in the arid area was set as a study area of groundwater vulnerability assessment.Firstly,zone map of assessment indicators was obtained by collecting data.Those indicators were overlaid in the MapGIS platform to get groundwater vulnerability division of each model.Secondly,results of unconfined groundwater vulnerability assessment corresponding to the four models were compared with the distribution and point coincidence rate of nitrate concentration?NO₃^--N?in unconfined groundwater in Shihezi City,respectively.At the same time,each model was used to comparison analysis with each other to obtain the most appropriate one in unconfuned groundwater vulnerability for Shihezi City.Lastly,the comparative analysis results were used to divide the inherent vulnerability and special vulnerability of groundwater in Shihezi City,and it can provide the theoretical basis for the protection and rational exploitation and utilization of groundwater in Shihezi City.The main research results and conclusions are as follows:?1?DRAV model and VLDA model are the evaluation model of groundwater inherent and special vulnerability in inland arid area,which is similar to the evaluation model of groundwater vulnerability in oasis city-Shihezi county scale in northwest arid area.VDEAL model is not suitable for evaluation of groundwater vulnerability in Shihezi City due to the evaluation of groundwater vulnerability in regional scale larger than county scale.?2?The evaluation results of DRAV model and DRASTIC model were basically the same in the evaluation of inherent vulnerability of groundwater.The evaluation result of VLDA model was superior to the evaluation result of VDEAL model in the evaluation of specific vulnerability of groundwater.?3?The common advantages of DRAV model and VLDA model were that the indicators of two models were less and easy to obtain,and could directly obtain the indicators based on conventional hydrogeological survey results and it did not need to re-engage in exploration work and it was economic and reasonable.The difference between DRAV model and VLDA model was that the spatiotemporal dynamic of result of VLDA model is better than DRAV model.?4?Comprehensively based on the evaluation results of DRAV model and VLDA model,very high and high vulnerability zone were mainly caused by the aquifer itself and human activities in the south of the town of Liangli-Shihezi town-Majiaping village in Shihezi City.