HR: 1340h
AN: H13I-1421    [Abstracts]
TI: Infiltration and Transport of Bromide and Cryptosporidium parvum in Vegetated, Tilted Soil Box Experiments
AU: * Harter, T
EM: ThHarter@ucdavis.edu
AF: University of California, Dept. Land, Air, and Water Resources, Davis, CA 95616-8628 United States
AU: Atwill, E R
EM: ratwill@vmtrc.ucdavis.edu
AF: University of California, Vet. Med. Teaching and Research Center, School of Veterinary Medicine, Tulare, CA 93274 United States
AU: Hou, L
EM: lhou@vmtrc.ucdavis.edu
AF: University of California, Vet. Med. Teaching and Research Center, School of Veterinary Medicine, Tulare, CA 93274 United States
AU: Carle, B M
EM: bcarle@vmtrc.ucdavis.edu
AF: University of California, Vet. Med. Teaching and Research Center, School of Veterinary Medicine, Tulare, CA 93274 United States
AB: In this paper we develop a conceptual model of the physics of flow and transport in packed, tilted, and vegetated soil boxes during and immediately after simulated rainfall events and apply it to 54 experiments implemented for three different soils at three different slopes and two different rainfall rates. Using an inverse modeling procedure, we show that a significant amount of the subsurface outflow from the soil boxes is due to macropore flow. The effective hydraulic properties of the macropore space were obtained by calibration of a simple two-domain flow and transport model that accounts for coupled flow in the matrix and in the macropores of the soils. While the macropore hydraulic properties are highly variable, linear mixed effects ( LME) modeling showed significant association with soil bulk density and with the rainfall rate. Macropore flow is shown to be responsible for both, tracer (bromide) and C. parvum transport through the soil into the underlying pore space observed during the 4 hours experiments. Over a 20 cm thick soil horizon, the soil attenuation rate for C. parvum due to straining in the soil matrix and due to filtration to the macropore surfaces is 0.6 (half an order of magnitude). The LME and logistic regression models developed from the soil box experiments provide a basis for estimating macropore hydraulic properties and the risk of C. parvum transport through shallow soils from bulk density, precipitation, and total subsurface flow rate information.
DE: 1832 Groundwater transport
DE: 1865 Soils (0486)
DE: 1875 Vadose zone
SC: Hydrology [H]
MN: Fall Meeting 2005