By using the momentum theorem and waterbalance principle, basic equations of slope runoff were derived, soil erosion by raindrop splash and runoff were discussed and a model was established for decribing hillslope soi...By using the momentum theorem and waterbalance principle, basic equations of slope runoff were derived, soil erosion by raindrop splash and runoff were discussed and a model was established for decribing hillslope soil erosion processes. The numerical solution of the model was obtained by adopting the Preissmann format and considering the common solution-determining conditions, from which not only the runoff and soil erosion but also their processes can be described. The model was validated by ten groups of observation data of Soil Conservation Ecological Science and Technology Demonstration Park of Jiangxi Province. Comparisons show that the maximum relative error between simulation and experimental data is about 10.98% for total runoff and 15 % for total erosion, 5.2% for runoffprocess and 6.1% for erosion process, indicating that the model is conceptually realistic and reliable and offers a feasible approach for further studies on the soil erosion process.展开更多
To date the roles of raindrop impact in sediment entrainment and transport processes of interrill soil erosion are not yet fully quantified.The objectives are to 1)evaluate the effects of raindrop impact on sediment e...To date the roles of raindrop impact in sediment entrainment and transport processes of interrill soil erosion are not yet fully quantified.The objectives are to 1)evaluate the effects of raindrop impact on sediment entrainment,2)systematically quantify the relative importance of raindrop-driven and flow-driven transport,and 3)characterize sediment size distributions in different sediment transport re-gimes.A loam soil with 48.4%sand and 23%clay was packed into flumes(L×W×H:1.8×0.5×0.1 m)and subjected to intensities of 60,90,120 mm h^(-1)at gradients of 5,10,and 16°.Air filter and tarp covers were used to vary impact energy and flow length.Results show that sediment is largely entrained by raindrop impact and transported by raindrop-impacted flow.Interrill erosion consists of two composite processes:raindrop-induced detachment/entrainment and raindrop-impacted flow transport.The former includes direct detachment by raindrop impact and'flow detachment'.The latter includes raindrop-driven and flow-driven transports.The proportions between the two transports vary with slope steepness,slope length,flow depth(or flow discharge),rainfall intensity,and sediment characteristics.Raindrop-driven transport is competent but inefficient,while the opposite is true for flow-driven transport.Because raindrop impact plays dual roles in detaching soil(and/or entraining sediment)and enhancing sediment transport,a drop energy factor must be included in interrill erosion models to adequately simulate the dual roles.More studies are required to derive a drop energy function that takes into consideration the rainfall energy dissipation by canopies of various plants under natural conditions.展开更多
基金The project supported by the National Natural Science Foundation of China(50309003)
文摘By using the momentum theorem and waterbalance principle, basic equations of slope runoff were derived, soil erosion by raindrop splash and runoff were discussed and a model was established for decribing hillslope soil erosion processes. The numerical solution of the model was obtained by adopting the Preissmann format and considering the common solution-determining conditions, from which not only the runoff and soil erosion but also their processes can be described. The model was validated by ten groups of observation data of Soil Conservation Ecological Science and Technology Demonstration Park of Jiangxi Province. Comparisons show that the maximum relative error between simulation and experimental data is about 10.98% for total runoff and 15 % for total erosion, 5.2% for runoffprocess and 6.1% for erosion process, indicating that the model is conceptually realistic and reliable and offers a feasible approach for further studies on the soil erosion process.
文摘To date the roles of raindrop impact in sediment entrainment and transport processes of interrill soil erosion are not yet fully quantified.The objectives are to 1)evaluate the effects of raindrop impact on sediment entrainment,2)systematically quantify the relative importance of raindrop-driven and flow-driven transport,and 3)characterize sediment size distributions in different sediment transport re-gimes.A loam soil with 48.4%sand and 23%clay was packed into flumes(L×W×H:1.8×0.5×0.1 m)and subjected to intensities of 60,90,120 mm h^(-1)at gradients of 5,10,and 16°.Air filter and tarp covers were used to vary impact energy and flow length.Results show that sediment is largely entrained by raindrop impact and transported by raindrop-impacted flow.Interrill erosion consists of two composite processes:raindrop-induced detachment/entrainment and raindrop-impacted flow transport.The former includes direct detachment by raindrop impact and'flow detachment'.The latter includes raindrop-driven and flow-driven transports.The proportions between the two transports vary with slope steepness,slope length,flow depth(or flow discharge),rainfall intensity,and sediment characteristics.Raindrop-driven transport is competent but inefficient,while the opposite is true for flow-driven transport.Because raindrop impact plays dual roles in detaching soil(and/or entraining sediment)and enhancing sediment transport,a drop energy factor must be included in interrill erosion models to adequately simulate the dual roles.More studies are required to derive a drop energy function that takes into consideration the rainfall energy dissipation by canopies of various plants under natural conditions.
