Characterizing detachment and transport processes of interrill soil erosion

Authors: Zhang, Xunchang; ZHENG, FENLI - Northwest A&f University; CHEN, JIE - Wuhan University; Garbrecht, Jurgen

Submitted to: Geoderma
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/2020
Publication Date: 6/26/2020
Citation: Zhang, X.J., Zheng, F., Chen, J., Garbrecht, J.D. 2020. Characterizing detachment and transport processes of interrill soil erosion. Geoderma. 376:114549. https://doi.org/10.1016/j.geoderma.2020.114549.
DOI: https://doi.org/10.1016/j.geoderma.2020.114549

Interpretive Summary: Soil detachment and sediment transport processes of interrill soil erosion (erosion between small channels in field) are not yet fully understood and quantified. Thus, the objectives are to (1) identify dominant interrill erosion regimes by comparing measured total soil splash by raindrop with total sediment wash load in surface flow, (2) estimate relative importance of raindrop-driven and flow-driven transports under selected flow conditions, and (3) evaluate the performance of widely used hydraulic parameters and empirical equations in predicting sediment delivery rates for both detachment- and transport-limiting interrill erosion regimes. Sediment discharge and raindrop splash were concurrently collected from two flumes (1.8×0.5×0.1m) and a 2.5-cm gap between them. Three rainfall intensities of 60, 90, and 120 mm h-1 were applied to three slopes of 9, 18, and 27% under two cover treatments. Results showed that beside raindrop detachment, raindrop-impacted flow can also detach soil on interrill erosion areas. Raindrop-driven sediment transport was estimated for the first time by dissipating raindrop impact energy with a screen cover. Raindrop-driven transport was found to increase with rainfall intensity and slope gradients. Flow power and one of the empirical equations performed well in predicting interrill sediment loss under both raindrop detachment-limiting and flow transport-limiting erosion regimes, suggesting that it is unnecessary to differentiate the interrill erosion regimes for developing operational prediction models. The findings would be useful to erosion scientists to develop better soil erosion prediction tools for use in soil and water conservation planning.

Technical Abstract: Detachment and transport processes of interrill soil erosion are not yet fully understood and quantified. Thus, the objectives are to (1) identify dominant interrill erosion regimes by comparing measured total soil splash with total sediment load of flow wash, (2) estimate relative importance of raindrop-driven and flow-driven transports under selected flow conditions, and (3) evaluate the performance of widely used hydraulic parameters and empirical equations in predicting sediment delivery rates for both detachment- and transport-limiting interrill erosion regimes. Sediment discharge and raindrop splash were concurrently collected from two flumes (1.8×0.5×0.1m) and a 2.5-cm gap between them. Three rainfall intensities of 60, 90, and 120 mm h-1 were applied to three slopes of 9, 18, and 27% under two cover treatments. Results showed that raindrop detachment was less than total flow wash under a screen cover. However, raindrop detachment was greater (less) than total wash at 9% (27%) with transition at 18% under a tarp cover. The results indicate that raindrop-impacted flow can detach soil, and therefore determination of limiting process by direct comparison between splash and wash load seems inappropriate. Raindrop-driven sediment transport was estimated for the first time by dissipating raindrop impact energy with a screen cover. Raindrop-driven transport was found to increase with rainfall intensity and slope gradients. Stream power and one of the empirical equations performed well in predicting interrill sediment delivery under both raindrop detachment-limiting and flow transport-limiting erosion regimes, suggesting that it is unnecessary to differentiate the interrill erosion regimes for developing operational prediction models.