At a catchment scale, the sediment storages of three small reservoirs were analyzed by a bathymetric survey and retrieval of sediment cores.
Depth and morphometry of reservoirs have been measured by a transportable echo-sounder attached to an inflatable boat; sediment cores were taken across the reservoir using a Beeker-Sampler.
By knowing age, size, depth and sediment thickness of reservoirs, sediment input into dams and sediment losses from contribution area could be calculated for a specific time period.

At a landscape scale, remote sensing techniques were used to extend information from field to larger landscape units. A digital elevation model was generated and a land cover map for the Ioba watershed was derived from Aster images by unsupervised classification (Graph).
These data served as input parameters for the spatially distributed soil erosion model WaTEM/SEDEM, which was applied to simulate soil erosion and sediment delivery into rivers/dams.

Simulated results allow both to quantify erosion/siltation rates at small reservoir scales and to identify soil erosion hazard zones in order to adjust soil and water conservation strategies to the required needs for long-term reservoir management.

Person in charge: Almut Brunner