effect of slope length on spatially variation of concentration

erosion is one of the important factors in soil degradation and decrease fertility and slope length is one of the most effective factors in land form and amount of erosion. the objective of this study was investigation of spatially variation of sediment concentration in slope length until to receive transport capacity. to obtain this goal a hill slope simulator system designed and manufactured. this system include 10 flumes, each has five meter length which after series them become fifty meters. this system can produce cumulative flow via fifty watering can tube which are install on flumes with one meter interval and each flume discharging is 100 cc. other variables include two type of soil and slope in three level 15, 22.5, 30 percent. three replications were used for each treatment and totally 18 experiment was done. in each experiment four samples were gathered from end of each flume and concentration was determined. complete randomized design with factorial arrangement was used for data analyzing. richard’s function was used for fitting a suitable curve on observed data. result was shown that effect of soil type on sediment concentration was not significant while slope and slope length effects was significant. otherwise sediment concentration in the two last flumes was located in same class which is shown that sediment concentration achieved to transport capacity in this slope length. also results were shown that richard’s function can simulate trend of concentration variety in slope length.