Estimation of erosion and sediment in the Vashmgir dam upstream basin

Abstract

Due to the importance of water and its vital role in human life, river studies and consequently studies on watersheds seem necessary. Golestan province with an area of 20437 square kilometers is located between latitude 36˚ 24΄ to 38˚ 0΄ north and 53˚ 51΄ to 56˚ 14΄ east. Gorganrood is one of the most important rivers in Golestan province and flows in the whole plain of Gorgan and divides it into two parts. Its catchment area is 10,250 km2. The main and important step in the study of erosion and sedimentation by experimental method is to determine and identify the forms and appearance of erosion. At this stage, various maps including river network, slope, geology, geomorphology, soil science and land use were studied; The map of the region was determined and the map was verified by interpreting aerial photographs and field visits. MPSIAC model was used to estimate the amount of erosion and sediment in the sub-basins. According to field studies and the results obtained, various types of erosions have occurred in the study area. According to the studies, the highest erosion was under the basin with code 1625220 (bed load 3.62 and with suspension 14.47) and the lowest erosion was under the basin with code 1624210 (bed load 0.32 and suspended load 1.3). Based on results, the sediment delivery ratio in the studied basins is between 23.6 to 39.6%. thus, the amount of special sediment varied between 1.6 to 18.1 and special erosion between 4.9 to 58.3 tons per hectare per year.