GIS مدل سازي فرسايش خاك و توليد رسوب در حوضه آبخيز چيخواب با استفاده از روش پسياك اصلاح شده و سامانه هاي اطلاعات جغرافيايي

Modeling of Soil Erosion and Sediment Production In Chikhab River Catchments Using PSIAC Method and GIS

Soil erosion is one of the main problems of watersheds in Iran. It can also be considered as one of the most important obstacles in achieving sustainable development in agriculture and natural resources. The sediments from the erosion of watershed catchments usually reach the river after each rainfall, and are combined with the sediments from the river walls and beds, and, as a result, endanger the effective life of dam storage. As such, quantitative and qualitative study of the soil erosion is vitally important in long term water structure plans. Since the initial study of constructing a dam across the Chikhab river (Moosian Plain in the Province of 11am) is currently underway, the present article makes attempts to present a model and investigate the erosion and sediment of the watersheds in the study area quantitatively, as well as, qualitatively. Methods for determining soil erosion and the river sediments were evaluated, and the optimum procedures were adopted. Using PSIAC method in a GIS environment, the information layers are produced, adequately weighted, and combined. The given catchments were divided into 576 sediment yield units from which 504 units are located in upper part of the likely dam. The minimum and maximum amounts of produced sediment were estimated 1.6 and 27.3 tons per hectare annually. The total amount of produced sediment calculated was 505737.3 tons per year, and the amount of the catchments deposit in the dam area reached 397298/3 tons per year equal to 264865/5 cubic meters. In terms of erosional classes and the sediment yield, the given catchments were divided into four classes of low, average, high and very high. In this category the given catchment falls in the high erosion class.