Zoning erosion intensity and sediment yield using MPSIAC in GIS (Case study: Ilam catchment)

Ilam catchment was chosen for a study to examine the performance of MPSIAC model and it efficiency in estimating erosion and sedimentation (R). Initially, according basin maps such as topography map, slope map, direction map, elevation levels map, geology and etc. were prepared by using a GIS software. The first two primary maps were prepared by overlaying elevation levels on direction map and geological map on slope map respectively. The primary maps were overlaid to obtain the basic map with 132 working unit and 4 specific features including elevation, direction, geology and slope. Using the basic map and other available information and maps and controlling working units using GPS system in nature, MPSIAC model determined cumulative scores of 9 effective parameters for each working unit which make up the R value in each working unit corresponding to their total area in the catchment. The value of sediment was determined by substituting the value of R in the equation of the above model. Results of this research showed that sediment delivery ratio (R) in this catchment was 58.333 and sediment yield score and sediment yield weight were 303981 m3/km2/year and 18234327 Tons per year respectively. Based on the results in the study and the table provided by MPSIAC model, it can be concluded that Ilam catchment can be considered as medium class with regards to erosion and sediment yield and its sediment delivery intensity is between 50 and 75. Also, it was observed that estimated sediment yield can be categorized in terms of erosion classification and quality of erosion as class 3 and medium level respectively.