Canadian Forest Service Publications

Scale-dependence of natural variability of flow regimes in a forested landscape. 2007. Sanford, S.E.; Creed, I.F.; Tague, C.L.; Beall, F.D.; Buttle, J.M. Water Resources Research 43: W08414, doi:10.1029/2006WR005299.

Year: 2007

Issued by: Great Lakes Forestry Centre

Catalog ID: 28299

Language: English

Availability: PDF (request by e-mail)

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The ecological integrity of riverine ecosystems is dependent upon the natural flow regime of the river system. 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 30-year simulated flow record was used to calculate natural variability in the flow regime, defined by the S80 [(90th percentile – 10th percentile)/median]. Flow variability under wetter conditions was similar across all basins, regardless of scale. Conversely, flow variability under drier conditions was scale-dependent, with smaller basins (<600 ha) showing a large range in variability and larger basins (>600 ha) showing a smaller range in variability that converged toward a constant with increasing area. The effect of basin area on flow variability suggested the existence of a representative elementary area (REA). Within the REA, morphometric sources of natural variability were determined through multivariate regression analyses. A combination of indices describing the near-stream riparian area within a basin, median basin residence time, and basin curvature was significantly related to flow variability under drier conditions. These findings present a potential management template for establishing reference conditions against which impacts of disturbance on flows throughout a regional drainage basin may be measured.