Basin of Namak Lake Using Statistical, DRASTIC and P-DRASTIC Methods

Statistical methods are widely used in environmental studies to evaluate natural hazards. Within groundwater vulnerability in particular, statistical methods are used to support decisions about environmental planning and management. In this study, the optimized of DRASTIC, Pesticide DRASTIC model parameters and land use layers (LU) were used to assess of pollution risk in catchment basin aquifer in south of Namak lake using of statistical methods.

Information layers were prepared, rated (deterministic and fuzzy-statistical), weighted (original and statistical) and combined (by Index-Overlay method) in GIS environment. For modeling, from nonlinear regression for fuzzy-statistical rating (scaling) and the Pearson correlation coefficients between of nitrate concentrations with scaling parameters of DRASTIC, P-DRASTIC model and sensitivity analysis (removal and single-parameter) were performed to determine and modify of parameters weighted.

As result P-RASIC-LU and RASIC-LU model with statistical rating and weighting, removal-parameter sensitivity analysis, determine as best selection model based on correlation coefficient = 62%, P-value = 0.01 and with parameters of net recharge, aquifer media, soil media, impact of vadose zone, hydraulic conductivity and land use with the weighty values of 3.1, 4.0, 4.1, 3.1, 2, 2 and 2.5, 4.63, 4.15, 3.03, 2, 1.96 consequently. According to this model, western and southern parts of the aquifer has high pollution risk due to high net recharge and coarse-grain material in the impact of vadose zone, soil and aquifer media.

Since reviewing of weight and rank of model parameters is limited personal opinions and increased model validation using statistical methods and GIS, It can be expected that favorable results to be followed for optimization of pollution risk model.