Sediment yield, runo ff and hydraulic characteristics in straw and rock fragment covers

Abstract

Soil loss is a major global challenge threatening the future of soil and water resources. The significant im-plications of soil loss necessitate the adoption of appropriate soil conservation practices and soil managementsolutions according to the regional climate. Investigation of the effects of soil cover on soil erosion process canprovide the information necessary for the success of soil and water conservation practices. In this study, theeffect of rock fragment and wheat straw covers on the hydraulic properties, runoff, and sediment yield wereinvestigated in plot scale laboratory experiments using artificial rainfall. Experiments were carried out on theplots prepared based on two types of soil cover (rock fragment, wheat straw) and three coverage ratios (35%,65%, and 90%) in addition to a control (bare soil) plot, each with three replications. In these experiments, 2 mlong, 0.55 m wide, and 0.30 m deep plots with a 15% slope were subjected to artificial rainfall with a duration of70 min and an intensity of 90 mm h−1. The results showed a significant difference at the 5% level between themean runoffrate of rock fragment cover (0.38 mm min−1) and that of wheat straw cover (0.42 mm min−1), butno such difference was found in terms of sediment production (Sig. = 0.73). The Wheat straw cover was moreeffective than rock fragment cover in increasing the Manning roughness (n) and Darcy-Weisbach friction (F)coefficients, andflow depth (h) and reducing the velocity (V), Reynolds (Re) and Froude (Fr) numbers. It wasalso found that, for both covers, increasing the coverage ratio increased theh,F, andnand decreased the runoffand sediment production,V,Re, andFr. After investigating the relationship between hydraulic properties andsediment concentration in different plots, a direct linear regression relationship with a relatively high coefficientof determination (R2> 0.614) and a significant relationship at the 1% level (P < 0.01) were found betweensediment concentration and discharge per unit width (q),V,h, andRe. In general, it can be concluded that rockfragment cover and wheat straw cover both have a satisfactory effect on the hydraulic properties and runoffandsediment production.