Precision Assessment and geostatistical methods for estimating the optimal level of groundwater table, Case Study: North West Kermanshah Plain

Successful management of groundwater resources using numerical models requires knowledge of spatial distribution of hydraulic heads and it's fluctuation, aquifer parameters and other input data. this paper's aim is application and evaluation of geostatistcal model for optimal estimation of Groundwater Table Level in an area of 999 sq km in part of the north west of Kermanshah plain. To achieving this, we used the data of Water table elevations in the 50 monitoring wells in studding area. Firstly we analyses the spatial correlation of monitoring wells With the use of measured elevations of the water table, experimental semivariograms were constructed that characterizes the spatial variability of the measured groundwater levels. Linear, Spherical, Exponential and Gaussian semivariogram models were fitted to the experimental semivariogram. The finally selected models were used to estimate the groundwater levels and estimation variance (which express the best accuracy of the estimated groundwater levels). Then 3 geostatistcal interpolation method (ordinary, sample and universal Kriging) applied to interpolate water table elevations from their measurements at random locations. The cross validation algorithm was used to estimation then 7 statistical indexes (RMSE, RMESu, RMSEs, MAE, MBE, d, R2) apply to evaluation and comparing 3 mentioned interpolation method. The results indicated that the ordinary kriging(OK) with exponential semivariogram and by including 8 neighbor were the best method for modeling and interpolating ground water table level in studding area.the out pout of this paper can be applied to optimization the locate of wells network. The water resource planner and decision maker in this field can apply this optimum interpolated water table to monitoring the spatiotemporal fluctuation of water table in this area by updating it's data.