Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 13 2 2009 10.5194/hess-13-205-2009 http://www.hydrol-earth-syst-sci.net/13/205/2009/ http://www.hydrol-earth-syst-sci.net/13/205/2009/hess-13-205-2009.html http://www.hydrol-earth-syst-sci.net/13/205/2009/hess-13-205-2009.pdf 205 216 2009-02-19 On the role of storm duration in the mapping of rainfall to flood return periods A. Viglione viglione@hydro.tuwien.ac.at G. Blöschl Institut für Wasserbau und Ingenieurhydrologie, Technische Universität Wien, Austria While the correspondence of rainfall return period TP and flood return period TQ is at the heart of the design storm procedure, their relationship is still poorly understood. The purpose of this paper is to shed light on the controls on this relationship. To better understand the interplay of the controlling factors we assume a simplified world with block rainfall, constant runoff coefficient and linear catchment response. We use an analytical derived flood frequency approach in which, following design practise, TP is defined as the return period of the intensity-duration-frequency (IDF) curve given storm duration and depth. Results suggest that the main control on the mapping of rainfall to flood return periods is the ratio of storm duration and catchment response time, as would be expected. In the simple world assumed in this work, TQ is always smaller or equal than TP of the associated storm, i.e., TQ/TP≤1. This is because of the difference in the selectiveness of the rectangular filters used to construct the IDF curves and the unit hydrograph (UH) together with the fact that different rectangular filters are used when evaluating the storm return periods. The critical storm duration that maximises TQ/TP is, in descending importance, a function of the catchment response time and the distribution of storm duration, while the maximum value of TQ/TP is mainly a function of the coefficient of variation of storm duration. The study provides the basis for future analyses, where more complex cases will be examined. Alfieri, L., Laio, F., and Claps, P.: A simulation experiment for optimal design hyetograph selection, Hydrol. Process., 22(6), 813–820, \doi10.1002/hyp.6646, 2008. Bradley, A A. and Potter, K W.: Flood frequency analysis of simulated flows, Water Resour. Res., 28, 2375–2385, 1992. Chow, V T., Maidment, D R., and Mays, L W.: Applied Hydrology, Civil Engineering Series, McGraw-Hill Book Company, International Edn., 572 pp., 1988. Gutknecht, D., Reszler, C., and Blöschl, G.: Das Katastrophenhochwasser vom 7. August 2002 am Kamp – eine erste Einschätzung (The August 7, 2002 – flood of the Kamp – a first assessment), Elektrotechnik und Informationstechnik, 119, 411–413, 2002. Kottegoda, N T. and Rosso, R.: Statistics, Probability, and Reliability for Civil and Environmental Engineers, McGraw-Hill Companies, International Edn., 735 pp., 1997. Linsley, R K., Kohler, M A., and Paulhus, J. L H.: Hydrology for Engineers, McGraw-Hill Book Company, London, Si Metric Edn., 492 pp., 1988. Packman, J C. and Kidd, C. H R.: A logical approach to the design storm concept, Water Resour. Res., 16, 994–1000, 1980. Pilgrim, D H. and Cordery, I.: Rainfall temporal patterns for design floods, J. Hydr. Eng. Div.-ASCE, 101, 81–95, 1975. Pilgrim, D H. and Cordery, I.: Flood Runoff, in: HandBook of Hydrology, edited by Maidment, D R., McGraw-Hill Companies, International Edn., Chap 9, 42 pp., 1993. Sivapalan, M. and Blöschl, G.: Transformation of point rainfall to areal rainfall: Intensity-duration frequency curves, J. Hydrol., 204, 150–167, 1998. Sivapalan, M., Blöschl, G., Merz, R., and Gutknecht, D.: Linking flood frequency to long-term water balance: Incorporating effects of seasonality, Water Resour. Res., 41, W06012, \doi10.1029/2004WR003439, 2005. Skøien, J. O. and Blöschl, G.: Catchments as space-time filters – a joint spatio-temporal geostatistical analysis of runoff and precipitation, Hydrol. Earth Syst. Sci., 10, 645–662, 2006. Wood, E F.: An analysis of the effects of parameter uncertainty in deterministic hydrologic models, Water Resour. Res., 12, 925–932, 1976.