Hydrologic Issues for Dams - Association of State Dam Safety Officials

intention of this study is to provide another independent data point and to verify theconclusions reached in the previous analysis.This investigation will use the draft precipitation values developed by the NationalWeather Service (NOAA Atlas 14, Vol 1, DRAFT) to produce a 1,000-year assumedthunderstorm event at Causey Dam, Utah. These values will be input to a rainfall-runoffmodel (HEC-1 or FHAR) to develop the 1,000-year thunderstorm flood event for CauseyDam. This peak discharge estimate will be compared with the frequency analysisdeveloped for Causey Dam. Causey Dam was selected as the test case because there isexisting at site paleoflood data to use in comparison, the drainage area is relatively small(137 mi 2 ), and it has a significant amount of streamflow and other comparative datadeveloped. The estimated completion date would be June 2001.Probabilistic Flood Hazard WorkshopThe introduction of risk analysis for dam safety signaled a significant change in the waythe Dam Safety Office and the Technical Service Center conduct flood hazardassessments. The purpose of this project is to compile, review, and evaluate currentstate-of-the-knowledge on probabilistic techniques used in flood hazard assessment.External experts in various aspects of flood hazards will be brought in to Reclamation onan individual basis. It is intended that each person present a Technical Update Lecture(1-2 hours). Members of the Flood Hydrology Group will subsequently meet with themto discuss their research in detail and potential technology transfer to Reclamation.About 12 experts participated in the workshop last year. These experts have helped theFlood Hydrology Group map out future methods, improve current methods, and plan aprogram for probabilistic flood hazard analysis to meet Dam Safety Office needs.ReferencesBras, R.L. (1990) Hydrology, An Introduction to Hydrologic Science. Addison-Wesley, Reading, MA, 643 p.Chow, V.T., Maidment, D.R. and Mays, L.W. (1988) Applied Hydrology.McGraw-Hill, New York, 572 p.Pilgrim, D.H. and Cordery, I. (1993) Flood Runoff. In Handbook of Hydrology,Maidment, D.R. (ed.), McGraw-Hill, New York, Ch. 9, pp. 9.1-9.42.Von Thun, J.L. and J.D. Smart (1996) Risk assessments support dam safetydecisions, USCOLD Newsletter, Issue No. 110, Nov 1996, U.S. Committee onLarge Dams.173Paper 22 – Swain et al