Study the Hydromorphologic Role of Gavi River Catchment Area in Feeding under Ground Water Resources of Mehran Plain by Using GIS

Under ground water that forms part of water cycle, is a reliable resource to provide human's need of water, but this phenomenon is an irreversible one in spite of a lot of other phenomenon. The study area includes Mehran plain’s aquifer in range of Gavi River’s catchment area that is one of the boarder catchment areas of the west of country in south of Ilam province. This river is the only supplier source of underground waters of Mehran plain that emanated from the heights of Kabirkoh and after passing through Bajak strait has entered in to Mehran plain and caused to nourishment of alluvial aquifer of the plain. The present research has been formulated with the purpose of recognition and creation the geomorphology factors of latrine plain and their relation with underground water sources and also preparation the applied maps in the course of recognition and environment management in this catchment. The method of this research is field and statistical analysis method. In this research Interpolation method has been used for surveying of geomorphology of the area and its relation with underground water of plain and drawing the balance maps, and correlation method has been used for surveying the relation between geomorphology forms parameters of water source. The results show that there has been a meaningful correlation between Alluvial fans, big torrent, hill and other geomorphology forms with the sources of underground water in the level of 99%.To evaluate the quality of groundwater of Mehran plain, the electrical conductivity (EC ) map is used. The results indicate that the quality of ground water in different areas of the plain, due to a variety of geological formations and structures are different. The minimum of electrical conductivity or EC has been increased from the southern and eastern margins of the plain, and in eastern and south-eastern of plain water pH value had been less than 7, that shows water is acidic.