Flow hydraulic characteristics and interrill erosion susceptibility of natural and constructed Soils from Candiota coal mining Area, RS, Brazil

摘要

Soil particles detachment in interrill soil erosion is due to water raindrop impact on the soil surface. The transport of soil particles is by overland broad sheet flow enhanced by the flow turbulence caused by raindrop impact. The objectives of thisstudy were to evaluate the flow hydraulic characteristics, to determine detachment rate and the interrill soil erodibility factor under simulated rainfall under laboratory conditions. Soil samples from natural and from 12 years old constructed soil weretaken from the 20 cm topsoil Candiota coal mine, RS, Brazil. Laboratory simulated rainfall of 85 mm/h intensity was applied during 90 minutes on bare soil at interrill unit plot of 0.59 X 0.59 m settled on 0.09 m/m slope. The results showed that the flowhydraulic was laminar and subcritical. The interrill soil erodibility factor (Ki) for the 12 years constructed soil was 1.03 X 10~6 kg s/m~4 which was lower than for the natural soil (1.82 X10~6 kg s/m~4) due to the higher resistance of the constructedsoil. The estimated Ki values were in the range of the soils used for the WEPP model (Water Erosion Prediction Project). Thus, they can be used to predict soil loss by erosion on hillslopes at the studied locations and soil types by applying this model.