干旱区生态环境知识资源中心

Runoff and soil erosion analysis was developed with simulated rainfall on a representative soil transect from the south Sahelian to Guinean zones in West Africa (15 degrees N to 05 degrees N). Twenty-six sites were studied and are presented in the first section, with the runoff and erosion measurement protocols. The second part presents a data interpretation based on erodibility by rain, latitudinal distribution of the sites and the most efficient characteristics for soil hydrodynamic behaviour. This synthesis, based on a new treatment of experimental data obtained from 1975 to 1981, distinguishes the lower hydraulic conductivities of the Sahelian and Sudanese soils from the higher ones measured in the Guinean zone. These differences are attributed to the soil surface fabric resulting from the combined effects of rain energy and runoff flow that control soil hydraulic properties. These surface features are formed in all conditions, but they are more stable and perennial in the arid north with its sparse vegetative cover and low biological activity than in the humid south with its continuous vegetative cover, high biological activity and hence deeper water percolation and storage. Our experimental study is a dynamic valuation of cartographic documents useful for didactic, development purposes, but also for providing new information sources for distributed models and GIS.