Alternative Management Practices for Water Conservation in Dryland Farming: A Case Study in Bijar, Iran

1.1 Water conservation Water conservation in the arid and semi arid regions is an important issue that influences both the environment and crop production. Runoff which is induced by rainfall can cause soil erosion which poses a dominant threat against long-term sustainability of farming (Derpsch et al., 1986). A further problem usually associated with runoff is the loss of soil particles that may pollute water bodies. Pollutants commonly found in runoff include soil particles, phosphorous, nitrogen, pesticides, etc. (Motavalli et al., 2003a) During runoff, soil particles in the form of displaced sediments are carried along with the flowing water. The runoff mostly settles around the edge of a dam and the sediments it contains will subsequently be deposited underneath the reservoir. This continuous and gradual silting of the dam over time will consequently affect its capacity to store water. The decrease in the capacity of reservoir depends on the concentration of soil particles in the river that supplies the dam. In spite of decades of concerted research efforts, sedimentation is still considered the most serious problem threatening the dam industry. The deposition of soil particles in the dam may decrease the efficiency of the dams’ turbines.