Investigating the effects of water transfer from Karkheh Dam on the physico-chemical properties of soil in Dasht-e Abbas plain, Ilam

This research investigates the changes of soil properties in Dasht-e Abbas plain due to the Karkheh water transfer to this plain. In this study, the maps of groundwater level changes before and after the utilization of irrigation system were prepared. Furthermore, to investigate the changes of soil characteristics, soil samples were collected from various project implantations and control areas and their parameters were determined and compared. The results showed that the groundwater level has been increased more than 15 meters during the study period and the depth of groundwater in some areas reached to less than 5 meters. The results indicated that the highest salinity belonged to the network coverage areas and evaporating zone having a saturation extract electrical conductivity of 10.62 and 9.26 ds/m respectively, while dry land areas have the lowest salinity with electrical conductivity of 0.8- 4.0 ds/m. The results further demonstrated that the water transfer of Karkheh Dam to Dasht-e Abbas due to the absence of drainage in 3 and 4 sub-networks, high volume of agricultural return water from flood irrigation, and inadequate development of groundwater exploitation has reduced the quality of soil in marsh area and flooding lands, and generally a "desertification" process after "combat to desertification" has occurred.