HR: 0800h
AN: H51D-1190    [Abstracts]
TI: Rain-Impact-Entrainment of Chemicals and Soil into Overland Flow in Saturated Areas: Theory and Experiments
AU: * Walter, M
EM: mtw5@cornell.edu
AF: Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853-5701 United States
AU: Gao, B
EM: bin.gao@yale.edu
AF: School of Environmental Studies, Yale, New Haven, CT 06511-2189 United States
AU: Parlange, J
EM: jp58@cornell.edu
AF: Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853-5701 United States
AU: Steenhuis, T S
EM: tss1@cornell.edu
AF: Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853-5701 United States
AB: Overland flow from riparian and other frequently saturated areas is a potentially important transport pathway between the landscape and aquatic ecosystems. Both raindrop driven processes and diffusion play important roles in the transfer of chemicals from soil to surface runoff, however, current transport models either do not consider the two processes together, or use "effective" parameters with uncertain physical definitions. We developed a physically based, solute transport model that couples both mechanisms and tested it with experimental data. One unique aspect of this study is that all the parameters needed to apply the model to our experiments were either directly measured or previously published, that is, there was no model "calibration" or "fitting." Our model assumes that chemicals near the surface of the soil are ejected into runoff by raindrop impact and chemicals deeper in the soil diffuse into a surface layer, or "exchange layer," via diffusion. The exchange layer depth and transfer processes are derived from the "shield" concept in the Rose soil erosion model (e.g., Rose, 1985, Adv. Soil Sci. 2,1-63.). The model's governing equations were solved numerically and the results agreed well with experimental data (R2 > 0.90). The model was also successfully tested against previously published experimental data by Leman and Ahuja (1983, J. Environ. Qual. 12(1), 34-40); these data were unique because they provided chemical concentrations in the soil profile as well as in the overland flow. This model provides insights into important processes relevant to landscape-river interactions and water quality protection.
DE: 1806 Chemistry of fresh water
DE: 1854 Precipitation (3354)
DE: 1860 Runoff and streamflow
DE: 1871 Surface water quality
DE: 0400 Biogeosciences
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting