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The sediment yield potential estimation of Fariabad and Kordian watersheds using MPSIAC model in the GIS framework
Seid Mohammad Tajbakhsh
College of Agriculture, University of Birjand
Hadi Memarian
College of Natural Resources, University of Tehran, Iran
Abstract
With due attention to the relatively suitable compatibility of MPSIAC model with the arid and semiarid conditions of Iran and lack of hydrometric station in region, in order to estimating of sediment yield and providing sediment yield and erosion intensity map in this watershed, we used modified PSIAC model. At first to enter the available raw data into the GIS framework topography, geology, geomorphology, land capability, soil hydrologic groups and plant cover maps using on-screen method were digitized. In the second stage, digitized maps were encoded based on the values of geology, soil erodibility, climate, land cover, land use, present status of erosion and channel erosion and sediment transport factors. Using the DEM layer, slope and rain (using the rain gradient equation) maps were provided and consequently topographic and runoff (using the rational method) factors maps were prepared. Then these factors maps were summed together and finally sedimentation score map was provided.The following equation on the sedimentation score map was applied and therefore sedimentation map was obtained:
Qs=38.77e0.0353R
Where:
Qs: specific sediment (m3/km2/yr)
R: sediment yield score
And then, with the applying Sediment Delivery Ratio (SDR) on the sedimentation map, erosion intensity map was obtained. Also, to obtain the work unit map, geology, geomorphology and hydrologic units maps were used and with overlaying this maps work unit map was obtained. Considering the upper part of this basin is rocky, the small work units were eliminated, and at last 28 work unit in Fariabad and 19 work unit in the kordian basins were obtained. Then by Spatial Analyst module facilities in the ArcView 3.2 software, the average of sediment yield, erosion and in any work unit and sub-basin was obtained.
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