Investigating Groundwater Extraction from the Hamedan-Bahar Plain,s Aquifer

Hamedan-Bahar plain is one of the groundwater restricted areas. The excessive groundwater extraction has led to significant drop in water table in the past three decades. Therefore، in this study water extraction from groundwater resources was calculated. Then، the amount of groundwater recharge was estimated based on the type of crop and irrigation system. Data from 2132 groundwater wells of Hamedan - Bahar plain during the years 2008 to 2009 was collected. The ArcGIS 9. 3 software was also used to find the spatial distribution of rainfall، the amount of runoff and the relevant groundwater recharge rate. The results showed that the groundwater recharge volumes were 96. 08، 41. 02، 76. 01، and 55. 8 million cubic meters and also the groundwater extraction volumes of the aquifer were 112. 6، 143. 7، 31. 5، and 7. 04 million cubic meters for spring، summer، autumn، and winter، respectively. In summer، the groundwater extraction rates at 15. 27 and 21. 69 percent of the plain،s area were five times and about three to five times more than the groundwater recharge rate، respectively. In spring، the groundwater extraction reate at the 3. 2 percent of the plain area was about three times more than the groundwater recharge and the groundwater extraction at 35. 55 percent of the plain area was about one to three times more than groundwater recharge. In autumn، the groundwater extraction rates at 0. 66 and 8. 88 percent of the plain area were three times and about one to three times more than the groundwater recharge rate، respectively. In winter، the groundwater extraction at 0. 54 percent of the plain area was three times more than the groundwater recharge and the groundwater extraction at 2. 08 percent of the plain area was about one to three times more than the groundwater recharge.