Dynamic mechanism and simulation of soil and water conservation practices in restraining runoff, sediment and nutrient losses on slopes

Author(s): Han, Y.; Feng, G.

Rainfall is a major dynamic driving factor of soil erosion and nutrient loss on different slopes. Soil and water conservation practices can change the dynamic process of soil and water losses, it is an important measure to reduce erosion and nutrient loss. In this study, four types of soil and water conservation practices, i.e., fish-scale pits, narrow terrace, shrub cover and agricultural landuse, were tested from 2001 to 2010. The results showed that all of these practices for soil and water conservation can significantly reduce soil erosion and nutrient losses. Compared with other practices, fish-scale pits most effectively reduced runoff, sediment and nutrient losses (the total losses of runoff, sediments, TP and TN were 20%, 2%, 10% and 36%, respectively, from the bare land in the same area), followed by 30% shrub coverage, narrow terrace and agricultural landuse. These soil and water conservation practices decreased shear stress, stream power, cross-section specific energy and soil detachment rate as well as reduced surface disturbances and soil erosion. The mechanisms of restraining soil and water loss by those conservation practices were quite different. In this study, rain intensity and erosion dynamic parameters (flow rate, Reynolds number, Froude numbers, Darcy resistance coefficient, Manning coefficient, shear stress, stream power, unit runoff power and cross-section specific energy) were considered as major factors in the empirical models for estimation of runoff, sediments, TP and TN at different runoff experiment sites. Statistical models were developed through stepwise linear regression analysis, correlation coefficient R of the models ranged from 0.65 to 0.99, indicating that simulated results were in good agreement with measured values.

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