Measuring sediment fluxes in periglacial reservoirs using water samples, LISST and ADCP

Climate change offers new perspectives for reservoirs near to the glacial environment. The reservoirs will benefit from increased water supply but are affected by increased sedimentation. Sediment transport was studied in Griessee. 61% of its catchment area is covered by glaciers. Particle size distribution (PSD) and suspended sediments concentration (SSC) were examined. Measurements were conducted with Niskin bottle sampler, laser in-situ scattering transmissometry (LISST) and acoustic Doppler current profiler (ADCP). They were compared with water samples. PSD and SSC show only minor fluctuations in the lake. The major part of the suspended sediments is silt, median diameters are between 5 and 10 μm. Average SSC is 80 mg/l. A minor turbidity current was detected with ADCP. LISST measurements were used for simultaneous measurement of PSD and SSC profiles. The combination of the three techniques was proven to be suitable for assessing sediment fluxes in periglacial reservoirs at high resolution