HR: 0800h
AN: H11F-0369    [Abstracts]
TI: A New Method to Evaluate Streamflow Recovery After a Drought
AU: * Kienzle, S W
EM: stefan.kienzle@uleth.ca
AF: University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4 Canada
AB: Under conditions of environmental change, occurrences of drought are expected to increase in number and severity. A river basin does not behave linearly to precipitation, and many drought indices, such as the Palmer Drought Severity Index (Palmer, 1965), are based on meteorological conditions, since they were developed for agricultural purposes rather than hydrological behavior of a river basin. A new method is presented to answer the question "When does the streamflow recover to normal conditions after a drought?", a question raised by many water managers who rely on adequate streamflow and reservoir levels, particularly municipalities, industry, power stations, and irrigation districts. The recession index is an indicator for the overall water basin conditions, and integrates all streamflow generating conditions, including the status of groundwater, wetlands, and basin wetness (or antecedent watershed conditions). The method is based on recession analysis of daily streamflow utilizing the RECESS program (Rutledge, 2004). The recession index K is calculated for all streamflow available records. Analysis of recession indices of streamflow in the Battle River Basin, a prairie watershed in central Alberta, Canada, was carried out using a minimum length of recession curves of 5 days. The analysis reveals drought years have associated low median annual K values, measured in days per log cycle, while normal to wet years have high median annual K values. The suggested method can be used to evaluate the overall status of a river basin in terms of runoff conditions by relating the latest measured recession index to the historical record. This gives an indication if, in terms of streamflow response, a river basin is still in a drought, in a phase of recovery, or fully recovered. Water managers can then predict water availability for the coming months. References: Palmer, W. C, 1965: Meteorological Drought. Res. Paper No.45, 58pp., Dept. of Commerce, Washington, D.C. Rutledge, A.T. and Mesko, 1996, Estimated hydrologic characteristics of shallow aquifer systems in the Valley and Ridge, the Blue Ridge, and the Piedmont physiographic provinces based on analysis of streamflow recession and base flow: U.S. Geological Survey Professional Paper 1422-B, 58 p. Rutledge, A.T. 2004 Program user guide for RECESS. water.usgs.gov/ogw/recess/UserManualRECESS.pdf
DE: 1812 Drought
DE: 1829 Groundwater hydrology
DE: 1860 Runoff and streamflow
DE: 1884 Water supply
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting