Mapping soil erosion and accumulation with the fallout isotope caesium-137

Abstract

The fallout isotope 137Cs has been used to trace the redistribution of soil in a cultivated paddock, in an upland catchment on the Darling Downs. The areal concentrations (mCi km-2) have been used to construct a caesiographic map which illustrates the areas of 137Cs depletion and build-up and the major areas of soil erosion and deposition, respectively, in the paddock. These areas have been graded on the basis of apparent relative intensity of erosion or deposition. Therefore, this method allows retrospective, quantitative estimates to be made of the extent and degree of soil redistribution within the last 3 decades. In addition the 137Cs results will be used to test mathematical models of erosion/deposition processes.