Farshid Alizadeh - Master of Water and Hydraulic Structures Engineering, University of Zanjan, Iran
Hamid Kardan Moghaddam - Assistant Professor of Research, Water research institute, Ministry of energy, Tehran, Iran, Tehran, Iran.

Soil erosion due to water is one of the most important causes of land degradation, and today it is considered as a serious environmental hazard around the world. Sediment is obtained from the erosion of rivers and their catchments. This process is one of the biggest problems in river engineering that many hydraulic structures, including dams in the world, face. Sedimentation phenomenon plays an important and influential role in hydraulic design and Considering the volume of dam reservoirs and also the useful life of these reservoirs, erosion and sediment transfer are phenomena that occur in different stages of conversion of rainfall to runoff and in the course of flow transfer. Some of the sediments being transferred are deposited in dam reservoirs, which can have adverse structural, economic, or even social consequences. Therefore, the amount of sedimentation in the dam reservoir must be estimated with acceptable reliability before its construction and also during operation. On the other hand, the exact amount of erosion or sedimentation is difficult in practice, but different methods have been proposed to estimate them. Such as reservoir hydrography, direct measurement of sediment thickness in reservoirs, remote sensing, use of mathematical and computer models and the use of hydrometric statistics to determine the volume of sediment in reservoirs, but due to different techniques and complexity of the sediment problem Insertion can not be recommended a comprehensive and cost-effective method, accuracy and at the same time low cost in all cases. In this study, in order to estimate the amount of sediment deposited behind the dam reservoirs, accurate mapping methods are investigated.

Soil erosion, Dam reservoirs, Mediment, Mapping methods, Bed load