EFFECT OF ORIENTATION OF SPATIALLY DISTRIBUTED CURVE NUMBERS IN RUNOFF CALCULATIONS1

Journal of the American Water Resources Association - Tập 36 Số 6 - Trang 1391-1400 - 2000
Glenn E. Moglen1
1Assistant Professor, Department of Civil and Environmental Engineering, University of Maryland, College Park, Maryland 2074 (E-Mail: [email protected]).

Tóm tắt

ABSTRACT: The NRCS curve number approach to runoff estimation has traditionally been to average or “lump” spatial variability into a single number for purposes of expediency and simplicity in calculations. In contrast, the weighted runoff curve number approach, which handles each individual pixel within the watershed separately, tends to result in larger estimates of runoff than the lumped approach. This work proposes further enhancements that consider not only spatial variability, but also the orientation of this variability with respect to the flow aggregation pattern of the drainage network. Results show that the proposed enhancements lead to much reduced estimates of runoff production. A revised model that considers overland flow lengths, consistent with existing NRCS concepts is proposed, which leads to only mildly reduced runoff estimates. Although more physically‐based, this revised model, which accounts directly for spatially distributed curve numbers and flow aggregation, leads to essentially the same results as the original, lumped runoff model when applied to three study watersheds. Philosophical issues and implications concerning the appropriateness of attempting to disaggregate lumped models are discussed.

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Journal of the American Water Resources Association

Tập 36 Số 6

1391-1400

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