Effect of doroud fault on hydrogeology of Doroud-Boroujerd alluvial aquifer,Lorestan province

Faults may are such a very important factor that makes the groundwater flow systems complicated. Doroud Fault, an active and strike-slip fault, is elongated in Doroud-Borujerd plain, NW-SE, as a segment of the main Zagros thrust. The aim of this study is evaluation of the Doroud Fault impact on alluvium aquifer regarding to the earthquake event at March 2006 using the groundwater iso-potential map, hydrographs of observation wells, electrical conductivitiy of groundwater, and the water table fluctuations in relation to the earthquake. Results show that the abrupt changes in the lithology and thickness of the aquifer as well as the groundwater salinity are probably associated with Doroud Fault’s movement. In addition, lagoonal fine grained sediments and low quality of groundwater observed in the eastern fault block. Moreover, the groundwater is channelized in the western block of the fault. This study suggests that the earthquake caused to approximately two meters rise in water table in the areas adjacent to the fault in one month comparing to 0.5 meter water table rise in other areas. Unexpectedly, the electrical conductivitiy of groundwater has a decreasing trend in the flow line direction, but with some local increasing anomalies along the fault zone.