A simple model for the transport of soil-dissolved chemicals in runoff by raindrops

Abstract: The development of a physically based model to simulate the transport of soil solutes in runoff has provided a better understanding of the mechanisms of transport and has assisted in the development of effective methods to control nutrient loss from soils and the pollution of waterways. A refined model has been applied to experimental data in which the presumed exchange layer was replaced by a mixing zone. Assuming that the exchange rate is controlled by raindrop splash, the effects of diffusion can be neglected and the exchange rate, k m , can be replaced by the variable e r , the raindrop-induced water transfer rate, removing the need to calibrate k m . To calibrate our model, laboratory experiments were conducted on disturbed loessial soil with three initial soil-moisture contents (5%, 15%, and 20%, measured gravimetrically) under three rainfall intensities (60, 96, and 129mmh−1) and three slope gradients (5, 15, and 25°). The model''s simulated data agreed well with the experimental data, demonstrating that the refined model captured the temporal behaviour of solute transport in the runoff. This study provides a new approach to the modelling of chemical transport by investigating the effects of raindrops on sediments from soil in surface runoff. [Copyright &y& Elsevier]