Analysis of Rating Loops of interrill erosion on Consecutive Storms under Laboratory Conditions

Studying sediment graph and sediment rating loops are as important and appropriate tools in analyzing sediment behavior with discharge changes and understanding the controlling role of discharge in sediment production during storms respectively. Therefore investigating the sediment behavior and variations in the form of sediment rating loops is so important in management planning and decisions. Accordingly the present study was therefore planned to analysis of sediment graphs and rating loops on consecutive storms under rainfall and soil erosion simulator condition. The simulations were done on a type of soil that was collected from Koujor region in Mazandaran Province. Towards this attempt, rainfall simulation experiments with intensities of 30 and 90 mm h-1were conducted in a set of 6 × 1 m plot with slope of 5 % during 6 consecutive storms. The results showed that total runoff increased with increasing of consecutive storms under rainfall intensities of 30 mm h-1 from 8.78 to 15.05 mm and under rainfall intensities 90 mm h-1 from 9.28 to 11.03 mm on the first and sixth storms respectively. But soil loss revealed more complex behavior than runoff so that occurred a sudden decrease in soil loss in fourth consecutive storm in compare with the other consecutive storms. Eventually, the results of rating loops on consecutive storms under rainfall intensities 30 and 90 mm h-1 reflected the variety of sediment output behavior in compare with discharge changes in different form of sediment rating loos including clockwise, counter clockwise and complex.