HR: 0830h
AN: H21C-08    [Abstracts]
TI: Continuous Daily Simulation of Chloride Flux for a 12 km² Forested Catchment in the Central Appalachians
AU: * Chanat, J G
EM: jgc3n@virginia.edu
AF: Department of Environmental Sciences University of Virginia, P.O. Box 400123, Charlottesville, VA 22903 United States
AU: Hornberger, G M
EM: gmh3k@virginia.edu
AF: Department of Environmental Sciences University of Virginia, P.O. Box 400123, Charlottesville, VA 22903 United States
AB: Quantifying the processes by which water and conservative tracers are transformed from rainfall into streamflow is a key prerequisite to understanding biogeochemical cycling, pollutant movement, and aquatic ecosystem functioning in headwater catchments. An ideal process-based model would represent the key features of the observed watershed-scale response in the simplest terms possible, while remaining faithful to hydrologist's general understanding of runoff generation mechanisms. We present a conceptual model for daily water and chloride flux for Paine Run, a 12.4 km² forested watershed in the Virginia Blue Ridge. The flow submodel is based on a decomposition of hydrologic response into "fast" and "slow" runoff components, and is parameterized independently of the solute data. Chloride flux is represented in terms of a cascading set of two travel-time distributions; one representing sporadic movement and evapoconcentration in the shallow subsurface, and the other representing continuous movement along deeper "baseflow" pathways. The model is calibrated against a seven-year series of weekly stream samples, as well as episodic data for selected events. We evaluate the model in terms of its simulation performance, its calibrated parameter values, and its credibility, addressing topics such as old water fraction in stormflow, overall residence time distribution, and frequency-domain response characteristics.
DE: 1030 Geochemical cycles (0330)
DE: 1806 Chemistry of fresh water
DE: 1860 Runoff and streamflow
DE: 1871 Surface water quality
SC: Hydrology [H]
MN: 2005 Joint Assembly