MODELING THE LONG-TERM DYNAMICS OF 137Cs IN RIVERS WITH DIFFERENT STRUCTURES AND TYPES OF WATERSHED CONTAMINATION

A. A. Bulgakov and A. V. Konoplev

A model of long-term dynamics of the river contamination after radionuclide fallout onto the watershed is dealt with. The model's main hypothesis is a direct proportionality between the annual mean concentration of the radionuclide in the river water and its mean content in the exchange form in the surface soil layer on the watershed. The model parameters can be estimated independently or determined through the model calibration based on data obtained in the first several years after the radionuclide fallout onto the watershed. The model was tested on 137Cs concentrations in the rivers running on the territory contaminated from the Chernobyl NPP accident. A comparison with measured concentrations has shown that the model can provide a fairly adequate description of long-term dynamics of radionuclides in rivers with different structures and types of watershed contamination.