Index Weight Sensitivity Analysis for Groundwater Pollution Risk Assessment Based on OAT–GIS

The accuracy of the weight assignment is an important basis for the conclusion reliability of groundwater pollution risk assessment, and analyzing or quantifying the sensitivity of the index weight is the difficulty for verifying the accuracy of the weight assignment. Taking 37 hazardous waste landfills in China for case studies and based on the index system being built for groundwater pollution risk ranking, the weight of each index was assigned by using Analytic Hierarchy Process of multi-criteria decision analysis (MCDA) model. Using the calculated minimum changes of weight, the weights of 14 indices sequentially changed in the module of weight sensitivity analysis (WSA) by using MCDA model based on one-factor-at-a-time (OAT) method. It quantified the weight susceptibility strength of 14 indices and analyzed the uncertainty in the weight assignment process of the index. Finally, it launched the visualization of spatial data statistics and analysis based on GIS. The results showed that, after weight change of the three indices including useful life, leachate quantity and terrain slope, among the 14 indices used for the groundwater pollution risk assessment in 37 hazardous waste landfills, the risk ranking of groundwater pollution in landfill changed greatest, indicating that its weight sensitivity is highest. The weight change of vadose zone permeability coefficient leaded to a minimum change of the risk ranking, and it illustrated that the weight sensitivity of this index is minimum. The method can effectively analyze and validate the accuracy of index weight assignment, identify the uncertainty of weights assigned, and help relevant decision makers have specific risk management.