Post-glacial sedimentation rate and patterns in six lakes of the Kokemäenjoki upper watercourse, Finland

Sediment distribution and accumulation in a chain of five lakes and Pääjärvi, southern Finland for the last ca. 10 000 years were investigated using acoustic sounding profiles. Lake bathymetry, catchment relief, geology and locations of input creeks and ditches have a critical effect on sedimentary dynamics in the study lakes. These factors cause considerable within-lake variation in the sediment depositions. Typically, the majority of accumulating matter and nutrients are removed from the flow system in sedimentation pools, which are seldom evident on bottom topography alone. However, detailed geological study can provide this information. The physical properties of long sediment sequences from each lake were investigated and dated using a palaeomagnetic dating method. The long-term sediment composition in the study lakes appeared to be more dependent on regional environmental factors, i.e. climate, whereas the rate of sedimentation was connected with soil types and land use in the immediate catchment area.