Identifying sediment sources using magnetic measurements: case of Abdelali Watershed (Eastern Rif, Morocco).

摘要

This note exposes the results of the magnetic measures made on samples of the catchment area soils upstream from the Abdelali dam (Rif, Morocco) and made on samples of the lake sediments to diagnose the state of degradation of soils and identify fields most sensitive to the erosion which constitute the sources of sediments which silted up the lake of dam. Magnetic susceptibility measures of the soil particles showed that the soils of upstream from the dam are subdivided into two groups according to their sensitivity for the erosion. Soils presenting low values of magnetic susceptibility (< 25 x 10(-8) m(3)/kg) which correspond to the very affected fields and the soils of which the magnetic susceptibility is included between 25 x 10(-8) m(3)/kg and 50 x 10(-8) m(3)/kg. These soils correspond to fields relatively more stable. The values of magnetic susceptibility of sediments of the lake are similar to those of the first group soils, what shows that it is these soils which constitute the major sediments sources who silted up the lake.