Stability of Confidence Levels for Flood Frequencies Using Additional Data

T. V. Hromadka II, Robert J. Whitley, Mick J. Smith

.

DOI: 10.4236/jwarp.2011.34029                

Abstract

A comparison of flood values based on prior data and new additional data at various confidence levels is given for five representative sites in Los Angeles, California. The methodology uses computer simulations to give the confidence level values and flood frequency curves. These calculations show confidence level increases roughly in the range of 5% to 10% using some quarter of a century of additional data.

Keywords

Runoff, Statistics, Simulation, Storm Water Management

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	U.S. Army Corps of Engineers, Los Angeles District, Los Angeles County Drainage Area (LACDA) Review, 1991.
[2]	County of San Bernadino, California, Hydrology Manual, 1983 and 1986.
[3]	T. V. Hromadka II, “Calibrating the Proposed Orange County EMA Hydrograph Procedure (A Study of Basin Factors and Coastal S-Graphs),” published by the Orange County Environmental Management Agency (OCEMA), Santa Ana, California, 1985.
[4]	T. V. Hromadka II, et al., “Derivation of a Rainfall-Runoff Module to Compute N-year Floods for Orange County Watersheds,” publication U.S. Army Corp of Engineers, Los Angeles Division, November 1987.
[5]	Interagency Committee on Water Data, Guidelines for determining flood flow frequency, Bull 17B, p. 28, Hydrol. Subcomm., Washington, D.C., March 1982.
[6]	D. R. Maidment, Ed., Handbook of Hydrology, McGraw-Hill, 1993.
[7]	Committee on Techniques for Estimating Probabilities of Extreme Floods, Water Science and Technology Board, Commission on Physical Sciences, Mathematics, and Resources, Nation Research Council, Estimating Probabilities of Extreme Floods, National Academy Press, Washington, D.C., 1988.
[8]	V. W. Griffis and J. R. Stedinger, “Evolution of Flood Frequency Analysis with Bulletin 17B,” Journal of Hydrologic Engineering, Vol. 12, No. 3, 2007, pp. 283-297. doi:10.1061/(ASCE)1084-0699(2007)12:3(283)
[9]	V. W. Griffis and J. R. Stedinger, “Log-Pearson Type3 Distribution and Its Application in Flood Frequency Analysis I:Distribution Characteristics,” Journal of Hydrologic Engineering, Vol. 12, No. 5, 2007, pp. 482-292. doi:10.1061/(ASCE)1084-0699(2007)12:5(482)
[10]	V. W. Griffis and J. R. Stedinger, “Log-Pearson Type3 Distribution and Its Application in Flood Frequency Analysis II: Parameter Estimation,” Journal of Hydrologic Engineering, Vol. 14, No. 2, 2009. pp. 209-212. doi:10.1061/(ASCE)1084-0699(2009)14:2(209)
[11]	V. W. Griffis and J. R. Stedinger, “Log-Pearson Type3 Distribution and Its Application in Flood Frequency Analysis III: Sample Skew and Weighted Skew Estimators, Parameter Estimation,” Journal of Hydrologic Engineering, Vol. 14, No. 2, 2009. pp. 121-130. doi:10.1061/(ASCE)1084-0699(2009)14:2(121)
[12]	J. R. Stedinger and V. W. Griffis, “Flood Frequency Analysis in the United States, Time to Update,” Journal of Hydrologic Engineering, Vol. 13, No. 4, 2008, pp. 199-204.
[13]	V. W. Griffis and J. R. Stedinger, “Flood Frequency Analysis in the United States,” Applications of Statistical Distributions in Hydrology, ASCE Monograph, 2011.
[14]	R. J. Whitley and T. V. Hromadka II., “Computing Confidence Intervals for Floods I,” Microsoftware for Engineers, Vol. 2, No. 3, 1986, pp.138-150.
[15]	R. J. Whitley, T. V. Hromadka II and M. J. Smith, “The Log-Pearson III Distribution in Hydrology, Chapter 6,” Environmental Sciences & Environmental Computing, Vol. III, P. Zannetti, et al., Editors. EnviroComp Institute, (http://www.envirocomp.org/esec), An Electronic Book, 2007.