Spatial Variability Zonation of Groundwater-table by UseGeo-statistical Methods in Central Region of Hamadan province

摘要

Today’s population explosion, industrial improve and agricultural development has increased the extraction of groundwater resources, As groundwater resources are the most important factors for development of arid and semiarid areas. In this study the geo-statistics methods are used to examine the spatial and timing variability of groundwater table of Central region of Hamadan Province in Iran, So the ground water statistical data in this region were accumulated and a data bank was prepared, Then the quality and the accuracy of data were controlled, Next the different interpolation techniques including Kriging, Inverse Distance Weight (IDW) to the power of 1 to 5, and Radial Basis Function method (Thin Plate Radial Function, Inverse Multi Quadratic and Multi Quadratic) and Cokriging method were used; After choosing the best interpolation methods using GSD and RMSE the spatial zonation map of groundwater table were drawn by Arc GIS. The analysis of geostatistical results appeared that the Spherical model was the best variogram specified to groundwater data in 1989, Circular model was the best in 1993 and 1999, and pent-spherical model was the best in 2006. Our findings got from investigation of interpolation methods by Cross validation showed that in all years of investigation, Cokriging method has had the less amount error in estimation and is the most suitable method. According these results the variable table of groundwater during the years of our research showed that the water table in this region has decreased noticeably and the use of these sources should be limited