<br />Model error was generally smaller for complex-distribution models DR3M, HSPF, PSRM and SWMM than for sim-
<br />ple distribution-models CUHP, HEC-I and TRZO. The average peak-flow RMS error for the complex-distribution
<br />models was 36 at Harvard Gulch and 50 at Surrey Downs, in contrast the average RMS for the simple-distribution
<br />models was 75 and 92, respectively. The RMS storm-volume error for complex-distribution models averaged 46 at
<br />Harvard Gulch and 27 at Surrey Downs, in contrast to an average RMS for the simple-distribution models of 65 and
<br />90, respectively. The error associated with the CUHP was generally similar to the error associated with the complex-
<br />distribution models, however. Michaud and Sorooshian (1994) also demonstrated that an uncalibrated complex-dis-
<br />tribution model (KINEROS) was more accurate than a simple uncalibrated SCS-curve model.
<br />
<br />The results of this test are not conclusive and do not indicate that one model performs better than another, The results
<br />merely show that the error associated with uncalibrated models can be substantial. The design of structures such as
<br />culverts, storm-sewers, detention basins, and other storm-water facilities based on uncalibrated model results could
<br />result in unnecessary costs when a model overpreditcs peak flows andstorrn volumes, and perhaps result in even
<br />more severe consequences when these structures are underdesigned because the model underpredicts peak flows and
<br />storm volumes.
<br />
<br />_ REFERENCES
<br />
<br />Alley, w'M. and Smith P~E., 1982, Distributed routing and rainfall-runoffmodel-- version II: U.s~ Geological Survey
<br />Open-File Report 82-344, 20 1 p~
<br />
<br />Aron, Gret, Smith, T.A.3rd., Lakatos, D.E, 1996, Penn State Runoff Model, PSRM C96, User Manual: Environmen-
<br />tal Resources Research Institute, Penn State, PA, Penn State Univ. 54 p.
<br />
<br />Bicknell, B.R~, Imhoff, J.C., Kittle, J.L., Jr., Donigian. A.S., and Johanson, RoC., 1993, Hydrological Simulation Pro-
<br />gram--Fortran, Users Manual for Release 10: EPA-600/R-93/144, Environmental Research Laboratory, Athens, Ga.,
<br />U~S. Environmental Protection Agency, Environmental Research Laboratory, 660 p.
<br />
<br />Ebbert, lC. Poole, J~E., and Payne, K.L., 1985, Data collected by the U.S. Geological Survey during a study of urban
<br />runoff in Bellevue, Washington, 1979-82: U.S. Geological Survey Open-File Report 84-064, 256 p.
<br />
<br />Huber, W.C. and Dickinson, R.E. 1988, Storm water management model version 4, part A: Users manual: U~S. Envi-
<br />ronmental Protection Agency Report EPA/600/3-88/00Ia, 569 p.
<br />
<br />Hydrologic Engineering Center, 1990, HEC-I Flood hydrograph package user's manual: U.S. Army Corps ofEngi-
<br />neers, Davis CA, 410 p.
<br />
<br />Julian, P~ Y. and Saghafian, Bahram, 1991, CASC2D: A two-dimensional watershed rainfall-runoff model, CASC2D
<br />user's manual: Report CER90-9IPYJ-BS-12, Colorado State University, Fort Collins, CO, 66 p~
<br />
<br />Julian, P. Y. and Saghafian, Bahram, and Ogden, EL., 1995, Raster-based hydrologic modeling of spatially-varied
<br />surface runoff: Water Resources Bulletin, Vol. 31, No.3, P 523-536.
<br />
<br />Michaud, Jeneand Sorooshian Soroosh, I 994,-Camparison ofsinJple versus complex distributed runoff models on a
<br />midsized semiarid watershed: Water Resources Research, Vol. 30, No 3, p. 593-606.
<br />
<br />Miller, J.E., 1984, Basic concepts of kinematic-wave models: U.S~ Geological Survey Professional Paper 1302,29 p.
<br />
<br />Soil Conservation Service, 1986, Urban hydrology for small watersheds: Technical Release No. 55,
<br />210-VI-TR-55, 156 p.
<br />
<br />-,1983, TR-20 Project formulation-hydrology (1982 version), Technical Release No. 20, 296 p.
<br />
<br />Tommer, IT., Loper, lE~, and Harnmett,K.M., 1996, Evaluation and modification of five techniques for estimating
<br />stormwater runoff for watershed in West-Central Florida: U.S. Geological Survey Water-Resources Investigations
<br />Report 96-4158, 37 p~
<br />
<br />Urban Drainage and Flood Control District, 1984, Urban storm drainage criteria manual, Vol. I Chps. Rainfall and
<br />Runoff, 1984 revision, Denver, e.O., 120 p.
<br />
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