Evaluation of Total Dissolved Solids and Quality Zones of Groundwater Using Vertical Electrical Soundings and GIS Method

Abstract

AbstractIn this research work a relationship has been identified between electrical resistivity (ρ) and total dissolved solid (TDS), to delineate subsurface TDS in groundwater in study area. TDS data have been collected from twenty-three wells spread across study area. At seventy locations vertical electrical soundings (VES) surveys were carried out. Quadratic least square technique has been used to generate an empirical model for TDS and ρ with a significant high coefficient of determination (R2) value of 0.73. Developed empirical model was validated using statistical tests and found to be very near to observed values. The statistical tests for validation of model, revealed that predicted and observed TDS values are also strongly correlated with R2 value (0.89), whereas other statistical tests (Standard Error of Estimate (SEE), Root mean square error (RMSE), Relative-RMSE (R-RMSE), Percent RMSC (%RMSE), t-statistic test, Volume Error (VE), Normalized RMSE (N-RMSE), Mean absolute error (MAE), Mean bias error (MBE), Mean absolute percent error (MAPE), Average index ratio (IR) and Percent of error (PE) have also revealed that established model have a good capability to predict TDS on the basis of ρ. On the basis of developed empirical model, groundwater TDS mapping has been carryout using ArcGIS within study area and delineated as fresh, brackish and saline zones.KeywordsCoastal aquiferTotal dissolved solidsVertical electrical soundingStatistical test