Quantifying sediment deposition and the spatial variability of sediment-associated metals in ponds treating urban diffuse pollution

Studies examining the accumulation of sediments within retention ponds have tended to provide spatially averaged estimates of deposition rates and have not accounted for the spatial variability of deposition and the potential role that developing morphological and sedimentary structures play in the routing of flow and potential contaminants within retention ponds. Additionally, studies examining the potential metal contamination of retention pond sediments have tended to examine individual cores at metre intervals. In this paper, the utility of ground-penetrating radar to provide a rapid means of delineating present pond-morphology and to also provide an estimate of sediment deposit thickness within retention ponds is explored. The spatial variability of metals in pond sediments at the centimetre-scale is also examined. Results show that metal variability around the inlet is high at the centimetre-scale, and that a degree of dependence exists between direction of flow and metal contamination. Copyright © 2007 IAHS Press.