بررسي فرسايش پذيري سازندها و اشكال فرسايشي در حوضه آبخيز ورده در شمال كرج با استفاده از مدل MPSIAC در محيط ILWIS

Investigation on erodibility of formations and erosion landforms in Vardeh drainage basin in northern Karaj, using MPSIAC Model in ILWIS environment

Vardeh Drainage Basin is located in the north of Karaj. This basin belongs to the Central Alborz structural zone and its climate is semi-humid. The area of Vardeh basin is 68,97 km2. Formations in this basin relate to Paleozoic, Mesozoic and Cenozoic that mainly include shale, tuffaceous shale, tuffaceus sandstone and limestone. Kahar Formation dating to Precambrian is the oldest and quaternary alluvial deposits are the youngest deposits at this basin. The aim of this study is to investigate erosion processes, erosion landforms and erodibility of formations using MPSIAC model in ILWIS environment. One of the methods for doing this study is classifying rocks of this basin in 5 erosion categories, dolomitic limestone of Soltaniyeh Formation have low erosion and Quaternary alluvial deposits have high erosion. Common shapes of erosion were identified by interpreting aerial pictures and conducting field studies. In Vv-4, sub-basin minimum shapes of erosion and in V-int sub-basin maximum erosion shapes of Rill, Sheet and Rock fall erosion are available. In MPSIAC model the effect of nine important factors on soil erosion and sediment yield were evaluated and numerical values were assigned to them in terms of intensity and weakness of each factor. Using the sum of those values for different factors, the level of deposit in the basin was calculated as Qs= 0.253e°ʹ036R and finally the map for each of the 9 factors was prepared in ILWIS environment. Considering identifying sub-basins with high severity of erosion and sediment yield V2and V3 sub-basins deposit, this basin has to be the first priority for soil protection programming.