ABSTRACT:
The curve number (CN) method deveseped by the Soil Conservation Service (now NRCS) for predicting peak runoff from Watershed has not been extensively tested in western regions of the United States. We used a 17 year rainfall and runoff record from a California Oak woodland watershed to compare the accuracy of CN as prescribed in the SCS National Engineering Handbook (NEH-4) with two alternative methods. Each method predicted mean annual peak runoff that was not significantly different from observed runoff and correlation between estimated and observed runoff from each of the three methods was statistically significant. However, the highest correlation coefficient showed that only 50% of the variability in the data were accounted for by any of the methods. The NEH-4 method under predicted maximum flows for the highest flow years. The more conservative Hjelmfelt method more frequently over-predicted peak flow. Overprediction provides a measure of safety when using the CN technique.
Footnotes
David Lewis is a Research Assistant and Michael Singer is a Professor of Soil Science in the Department of Land, Air, and Water Resources Department of the University of California. Kenneth Tate is a Rangeland Watershed Hydrologist in the Department of Agronomy and Range Science at the University of California.
- Copyright 2000 by the Soil and Water Conservation Society
This article requires a subscription to view the full text. If you have a subscription you may use the login form below to view the article. Access to this article can also be purchased.