Assessment of spatial redistribution of Chernobyl-derived radiocaesium within catchments using GIS-embedded models.

The Chernobyl accident has resulted in surface contamination by radiocaesium ( 137 Cs) over vast areas of eastern and northern Europe. This surface contamination has been subject to changes due to physical decay and lateral transport of contaminated soil particles, which has resulted in a still on-going transfer of radionuclides from terrestrial ecosystems to surface water, river bed sediments and flood plains. Evidence from previous research show that this may cause a local enhancement of 137 Cs uptake into food chains. Although 137 Cs has been used as tracer in many soil erosion modelling studies, spatially distributed erosion and sedimentation models have not been widely used for evaluation of radionuclide transport within and from river catchments. This paper presents an integrated set of GIS-embedded models that are being developed in the framework of the EC-financed project SPARTACUS to assess redistribution of radionuclides at the catchment scale. These models are implemented in the spatio-temporal modelling language of the raster-GIS PCRaster and account for water runoff, soil erosion and deposition, and sediment-associated radionuclide transport.