Unification in Estimation of Confidence Intervals

by T. V. Hromadka, II, Williamson and Schmid, Irvine, United States,
R. J. Whitley, Williamson and Schmid, Irvine, United States,
J. J. DeVries, Williamson and Schmid, Irvine, United States,



Document Type: Proceeding Paper

Part of: Water Resources Planning and Management and Urban Water Resources

Abstract: One area of future development needs in technology pertaining to surface runoff hydrology is the unification of techniques used by govermental agencies in the estimation of surface runoff quantities. Currently, the usual case is each governmental agency adopts its own methodology or hybridization. The policy as to which set of methods to be used are embodied in a document called the hydrology manual. With computerization, however, the various agencies become aware of differences in runoff predictions, due to methodology, and question why these differences occur and whether such differences are valid. An important problem in urban hydrology is estimating the change in peak discharge due to urbanization of the catchment. It is also useful to be able to give confidence intervals which to some extent describe the uncertainty in this estimated increase in peak discharge. That is, an important problem to be solved is quantifying how the catchment peak flow rate will be affected by urbanization, and to what level of confidence is this estimate of change in peak flow rate. In this paper, a statistical model is developed to analyze the ratio between the pre-urbanized and post-urbanized catchment peak flow rates. Using this ratio of peak flow rates as the criterion variable, T-year return frequency estimates can be obtained, as well as lower one-sided confidence interval estimates, including 50-percent and 85-percent levels.

Subject Headings: Runoff | Peak flow | Urban areas | Confidence intervals | Flow rates | Catchments | Water discharge

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