Using cesium-137 and landform classification to develop a net soil erosion budget for a small Canadian Prairie watershed

Abstract

Summary The primary aim of this study was to determine if the relationship between objectively defined landform classes and soil erosion identified by Martz & De Jong (1987) for a small, agricultural Prairie basin, could be exploited in the calculation of soil erosion budgets and sediment yields. A secondary aim was to assess the degree to which the relationship described in that earlier study might apply to other small agricultural basins in the region. Following the earlier study, computer-assisted analysis of a digital elevation model was used to subdivide a 65 ha cultivated basin near Saskatoon, Saskatchewan into landform classes, and137Cs measurements at a sample of sites over the basin were used to determine the mean net erosion of each class. Mean net erosion differed significantly between the classes, but the relationship of net erosion to landform class in the study basin differed from that reported for the basin where the classification was originally applied. This was thought to be due largely to differences in soil properties between the basins. The mean net erosion and area of the landform classes were used to calculate a net erosion budget for the basin. The total soil loss from the basin given by the erosion budget agreed closely with the sediment accumulation, also measured using137Cs, behind a dam at the basin mouth, and was consistent with the few sediment yield data available for other small Saskatchewan basins. It was concluded that the landform classes provided a reliable basis for the empirical calculation of the net erosion budget and sediment yield.