Analysis of Observed Sedimentgraphs and Rating Loops on Storm Basis in Educational Watershed of Tarbiat Modares University, Iran

Studying temporal variation of suspended sedimentgraph is an important tool in soil and water resources management of a watershed. At present, most of estimates and studies for sediment generation are accomplished by sediment rating curves, while their accuracy has ever been questionable. Therefore, sedimentgraph analysis has great importance in sediment studies in watersheds. Hence, the present study was conducted in educational watershed of Tarbiat Modares University located in Mazandaran Province, Iran, with an area of some 50000 ha to analyze sedimentgraph and rating loops of seven observed storm events from 24 October 2007 to 21 July 2008. Individual analysis of sedimentgraphs and hydrographs ascertained complexities governing the aforesaid forest watershed. The results of studying sedimentgraphs with duration of 6 to 13h verified an average sediment yield of 15.830±3.756 tons. It also showed that most of the sedimentgraphs are in advance with an average interval of +2.600±2.881 h. The developed rating loops were also recognized as clockwise type. However, this behavior varied in corresponding with sand and gravel mining and storm coverage area. The results owing to providing appropriate elementary data needed for watershed management approved the necessity of further detailed studies in storm scale and different time bases.