Contribution of multi-temporal SPOT data to the mapping of a soil erosion index. The case of the loamy plateaux of northern France

Abstract

Loamy soils of the northern European loess belt commonly are exposed to erosion caused by concentrated runoff. Such runoff generates mud flows that, when strong, may create major problems because of the damage they cause to infrastructure. Using multi-temporal SPOT data and GIS technologies, a method is proposed and tested for mapping surfaces affected by runoff, as well as for evaluating the effectiveness of such remotely sensed index to infer erosion. This work is part of a major research effort, jointly undertaken by BRGM and INRA, which develops a predictive approach for monitoring erosion at a regional scale. Results have shown that the method for estimating surfaces affected by runoff, is quite reliable for areas underlain by loamy soil. However, the correlation between such surfaces and effective erosion, i.e. soil loss quantitative measurements, remains low, even though it confirms the possibility of using statellite data rather than other sources of information. It became clear that the conditions of low erodibility during the period of our study were a handicap for this type of validation; another problem is caused by the choice of the optimum observation period, which can vary as a result of winter rainfall events.