Modeling Alluvial Aquifer Using PMWIN software and Evaluation of Subsidence Phenomenon in Asadabad plain, Hamedan Province, Iran

The Study area in Asadabad plain is part of the Karkhe river watershed. Reduce in rainfall and increase in exploitation of groundwater resources led to a sharp drop in groundwater levels and subsidence’s phenomenon in recent years has. The aim of this study is the hydrogeological evaluation, a better understanding of aquifer and optimal utilization of groundwater resources by using available data. In order to provide the mathematical model, geological, meteorological, hydrological and hydrogeological data were collected and then analyzed. Then according to the aquifer’s conceptual model, the mathematical model was developed with PMWIN software. The model was implemented and calibrated for 2006-2007 with 12 stress periods. The sensitivity analysis showed that model has a more sensitive to hydraulic conductivity. The model was verified with observed data for next year (2007-2008). The results show that model is unable to simulate aquifer’s natural conditions. The main reason was the uncertainty in input data and lack of piezometers in a large part of the aquifer's second layer. Study the effective factors on subsidence phenomenon (groundwater level fall, aquifer’s type, aquifer’s thickness and existence confined aquifer) showed that the central and southern parts of the plain have more vulnerable capabilities than the subsidence phenomenon.