In 1993 - seven years after Chernobyl - concentrations of radioactive caesium in the topsoil of the Ukraine's Rovno region suddenly tripled. Within a year, however, the levels were almost back to pre-1993 levels

This surprising result illustrated how little was known about how radioactive particles travel through ecosystems. In the case of Rovno, some 350km west of Chernobyl, the answer lay in the floods of 1993, with preliminary analyses suggesting that levels of 137Cs were increased both through deposition of contaminated suspended matter and through the uptake of floodwater by submerged plants. A better understanding of these processes is essential for assessing, managing and restoring contaminated land. Hence the Stress (Spatial and Temporal Radio Ecological Survey Systems) project, which brought researchers together from Belarus, Denmark, the Netherlands, Russia and Ukraine. The researchers collected field data and analysed them using geostatistical techniques and Geographical Information Systems (GIS). Apart from developing a better understanding of 137Cs hydrochemistry in flood water and creating an environmental decision support system to help manage the next flood, the project built new scientific networks enabling transfer of these sophisticated techniques between the countries involved.