Submitted to: Catena
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/10/2001
Publication Date: 1/1/2002
Interpretive Summary: Soil erosion on upland areas is a multi-faceted process involving rainfall and surface flow as the erosive agents and the soil with a varied set of characteristics, topography, and surface conditions as the erodible medium. Most of the erosion research focus has been on the soil itself and the different soil surface conditions that affect soil erosion, such as crop residue, surface cover, soil management, etc. Comparatively little work has been conducted on erosion as affected by different hydrologic regimes and subsurface conditions. This article summarizes the findings of a series of laboratory experiments that determine soil erosion for different rainfall intensity sequences, surface roughness, and the subsurface soil water pressure regime. The soil chosen was a highly erodible loess soil. The results show that differences in the rainstorm intensity regime and differences in surface roughness appreciably impact soil losses. The results also indicate the large effect that the subsurface soil water pressure has on sediment yield. This information will be helpful to improve dynamic predictions of soil loss and to devise better strategies for soil erosion control.
Technical Abstract: Soil erosion is a complex phenomenon involving detachment and transport of soil particles, storage and runoff of rainwater, and infiltration. The relative magnitude and importance of these processes depends on a host of factors, including climate, soil, topography, cropping and land management practices, control practices, the antecedent conditions, and the size of the area under consideration. In this study, the results of a series of experiments are reported which summarize the soil loss and runoff response from a 0.6 m by 3.75 m area to different rainstorm regimes, slope steepnesses, subsurface soil water pressures, and surface roughness under controlled laboratory conditions using a flume and rainfall simulator as water applicators and a laser microreliefmeter and tensiometric system as soil response measuring devices. The soil chosen was a highly erodible Grenada loess (fine silty, mixed, thermic, Glossic Fragiudalf). The results showed: 1) a sequence of rainstorms of decreasing intensity on an initially air dry smooth surface caused more soil loss than a sequence of similar storms of increasing intensity; 2) the surface roughness-sediment concentration relationship was not monotonic in nature; 3) subsurface soil water pressure substantially affected sediment concentration in runoff but only marginally impacted runoff amounts; 4) initially smooth, uniform surfaces may yield less soil loss than initially rough surfaces; 5) interrill runoff occurred as spatially varying flow in which flow patterns determine the locations of rills.