HR: 1340h
AN: H13F-0474    [Abstracts]
TI: Vulnerability to Episodic Acidification of Streams in Shenandoah National Park
AU: * Deviney, F A
EM: deviney@virginia.edu
AF: University of Virginia, Department of Environmental Sciences Clark Hall, Charlottesville, VA 22903 United States
AU: Rice, K C
EM: kcrice@usgs.gov
AF: U.S. Geological Survey , P.O. Box B , Charlottesville, VA 22903 United States
AU: Webb, J R
EM: rwebb@virginia.edu
AF: University of Virginia, Department of Environmental Sciences Clark Hall, Charlottesville, VA 22903 United States
AB: Characterizing magnitude, frequency, and duration of acid-neutralization capacity (ANC) depression in streams requires a time series of ANC values at a time scale appropriate to the resources at risk from ANC depression. For small catchments, ANC excursions on the order of hours may be critical. However, hourly observations of ANC are prohibitively expensive. On the other hand, hourly observations of discharge are relatively inexpensive. We develop transfer function time series models with outlier correction to predict hourly ANC from discharge for five catchments in Shenandoah National Park, Virginia. These models outperform simple regression. The catchments range in size, are situated on different geologies and exhibit other physiographic differences. We use the predicted hourly ANC time series to calculate annual low-ANC values for various time spans: 2, 6, 12, 24, 72, 96, and 168 hours. We then fit Pearson type III distributions to the annual low-ANC values and extrapolate those distributions to other catchments in Shenandoah National Park where Park staff monitor fish populations. This allows us to generate maps of, for example, the 72-hour, 4-year low-ANC frequency for the catchments considered.
DE: 1806 Chemistry of fresh water
DE: 1860 Runoff and streamflow
DE: 1869 Stochastic processes
DE: 1871 Surface water quality
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting