ASSESSMENT OF SOIL MOVEMENTS IN A WATERSHED FROM CS-137 DATA AND CONVENTIONAL MEASUREMENTS (EXAMPLE - THE PARISIAN BASIN)

Soil degradation, by water and wind erosion is a matter of growing con cern in Europe. Caesium-137, paired with conventional methods, is used in many countries to assess the extent of soil erosion. This techniqu e was tested in a small watershed of the Laonnois area (Parisian Basin ) which has been monitored for several years by traditional computeriz ed and automatic techniques. This study makes possible a comparison of both methods. The first results suggest a difference in the soil loss estimates in a ratio near 1:1.6. However, the two methods appear comp lementary: caesium-137 can be used to estimate rapidly the magnitude a nd the spatial pattern of soil erosion, while the conventional techniq ues can produce more accurate soil loss data and can be used for in-de pth investigations of the influence of various factors (ground cover, cultural practices, etc.) on soil erosion.