HR: 1340h
AN: H23D-1461    [Abstracts]
TI: Scale-Dependence of Natural Variability of Flow Regimes in a Forested Landscape
AU: * Sanford, S E
EM: sesanfor@uwo.ca
AF: Department of Geography, University of Western Ontario, London, ON N6A 5C2 Canada
AU: Creed, I F
EM: icreed@uwo.ca
AF: Department of Biology, University of Western Ontario, London, ON N6A 5B7 Canada
AB: The natural flow paradigm states that rivers should be managed to preserve their natural flow regimes. Maintaining natural variability in the flow regime is critical for conserving the structure and function of riverine ecosystems. This research seeks to determine relations between natural variability in the flow regime and basin scale. A distributed hydrologic model was used to characterize the natural flow regime of basins from first to fifth order within tributaries of the Batchawana River in the Algoma Highlands of central Ontario using the Range of Variability Approach (RVA). A thirty-year simulated flow record was used to calculate natural variability in the flow regime, defined as the S80 ((90th percentile - 10th percentile) / median). A scale-dependence in the S80 of these flows, and particularly low-flow parameters, was observed. Basins less than a threshold between ca. 400 and 600 ha had a large range in S80, while basins greater than 600 ha had a smaller range that converged towards a constant with increasing area. This represents the potential for a representative elementary area (REA) to exist with regard to interannual variability of some flow parameters. Below the REA, the mean of the ln ( /To tan B) distribution was significantly related to the S80 mean summer flow and 90-day minimum flow (p<0.001). This research demonstrates the scale-dependence of natural variability of flows, important for establishing reference conditions against which impacts of disturbance on flows throughout a drainage basin may be measured.
DE: 1800 HYDROLOGY
SC: Hydrology [H]
MN: Fall Meeting 2005