Short-Term Temporal Variations in Runoff, Sediment Concentration in Different Land uses under Two Rainfall Intensities

Land use change has a significant effect on soil physical and chemical characteristics and subsequent changes in hydrologic responses such as runoff volume and sediment concentration. Although numerous studies have mentioned vegetation cover impacts on soil erosion, relatively a few studies have quantified the temporal variation of hydrological response of runoff and sediment production under different land use and rainfall intensities. A replicated field-based rainfall simulation were performed at two selected intensities (51 and 86 mmh-1) in 1m2 plots on four types of land cover (rangeland, bare soil, straw mulching, and lentil filed) at Gonbad University research site. Behaviors of runoff and sediment concentrations during 30 min rainfall simulation test were made at every 6 min intervals. The ANOVA results showed that there were significant differences between the hydrological response of the soil depending on the vegetation covers and rainfall intensities over time. The different land uses in this study resulted in runoff volumes ranging from 2.3 lit to 24 lit and from 6.38 to 46.8 lit at 30 min for 51 and 86 mmhr-1 rainfall intensity, respectively. On the other hand, bare soil was most easily detached, followed by straw mulching, lentil, and rangeland. Although Student's t-test showed that there were significant effects of rainfall intensities in runoff volume on all plots except on bare soil plot. These differences are all significant at the P = 0.05 level. Moreover, only there was a statistically significant difference in sediment concentrations of rangeland plot.