Effect of aquifer management on groundwater changes in Gareh Bygone Plain

In undeveloped and less developed countries of arid zones, the easiest way for water supply is withdrawal of groundwater. The negative perception of this method of water discharge is clear. Spreading floodwater is one of the water resources management strategies in arid and semi-arid zones that has positive impacts on groundwater resources. The aim of this research was to demonstrate the impact of floodwater spreading on quantity of groundwater in Gareh Bygone Plain, Fasa, Fars province, Iran. Annual changes of water level was determined by reviewing water level of monthly data (1992-2013) of four piezometric wells. Despite to the spreading floodwater, the general trend of groundwater level was declining. Thus, for demonstrating the role of the floodwater spreading in groundwater recharge, changes in groundwater levels were investigated in the years of increases and decreases of floodwater. Results showed that the least recession is in piezometric wells 1 and 3. Piezometric well 1 due to the effect of fault and piezometric well 3 due to the effect of floodwater spreading. Results of Principal Components Analysis (PCA) of monthly water level in four piezometric wells showed that the first component as the most important indicator of recession of water level in the region is more than 83% of the variance. Sorting PCA loadings on the first component, represents a high recession in piezometric wells 2 and 4 that corresponds with the results of recession map of the plain. Piezometric well 2 due to evapotranspiration of trees and piezometric well 4 due to excessive extraction of water for agriculture in the area showed the most recession.