Determination of Hydraulic Conductivity Based on Corrected Transmissivity and the Effect of Wells Density and Excess Water Harvesting on Shabestar Plain Aquifer

Shabestar plain is located in the east of the Urmia Lake basin. For study of groundwater and for obtaining aquifer hydraulic properties of Shabestar plain aquifer, pumping tests have been carried out on available utilization and experimental wells. The best locations for groundwater harvesting could be determined by estimating and generelizing of hydraulic transmissivity and conductivity parameters and irreparable damages to the aquifer because of unusual harvesting could be prevented. In order to increase the validity and accuracy of the pumping test, the selected wells should be fully penetrated wells. But, due to the unavailability of aquifer thickness during drilling, many drilled wells were incomplete, which were used in pumping tests. So, with generation of resistance against inflow the calculated transmissivity was less than the actual value. In this research, after accurate estimation of bedrock position using electrical resistivity and drilling logs, the aquifer thickness was determined in the location of wells for using in the pumping test, and transmissivity coefficients of incomplete wells were corrected by Kozeny's equation. Then hydraulic conductivity was calculated and interpolated to whole area. The average transmissivity coefficient and average hydraulic conductivity of the Shabestar Plain aquifer were 410 m2/d and 4.52 m/s, respectively. Investigating position and discharge rate of wells and the impact of this kind of harvest on the groundwater level showed that the high density of harvesting wells located in low hydraulic conductivity areas led to severe local drop in the groundwater level of the Shabestar plain aquifer.