Inter-Storm Variability of Coefficient of Variation of Runoff Volume and Soil Loss during Rainfall and Erosion Simulation Replicates

Investigation of inter-storm variability of runoff and soil loss characteristics helps experts and decision makes better understanding of hydrological response. However, this important has been less considered in the world, especially developing countries. The present study was therefore planned to evaluate the effect of different rainfall intensities and slopes on inter-storm variability of Coefficient of Variation (CV) of runoff volume and soil loss in three replicates. To achieve the objectives, a set of laboratorial experiments were conducted using rainfall simulator and 6×1 m erosion plot with a depth of 0.5 m and a slopes of 5, 15 and 25 %. Rainfall intensities of 30, 60, and 90 mmh-1 were applied to a soil sampled from Kojour rangeland watershed, northern Iran. The results described an increasing trend in runoff volume and soil loss inter-storm CV with increase in rainfall intensity at slopes of 5 and 15%. While, no trend was distinguished for inter-storm CV for runoff volume and soil loss with increase in slopes and different rainfall intensities except soil loss inter-storm CV in rainfall intensity of 90 mmh-1 at different slopes. The lowest and the highest coefficient of variation were also respectively found in means for runoff volume (i.e., 4.80 and 17.10 %) and soil loss (i.e., 17.28 and 87.96 %). The results of the study emphasized the necessity of considering the inter-storm variability of runoff and soil loss components in different replicates with regard to appropriate rainfall intensity and slope for analyzing the watershed system processes.