Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 11 4 2007 10.5194/hess-11-1515-2007 http://www.hydrol-earth-syst-sci.net/11/1515/2007/ http://www.hydrol-earth-syst-sci.net/11/1515/2007/hess-11-1515-2007.html http://www.hydrol-earth-syst-sci.net/11/1515/2007/hess-11-1515-2007.pdf 1515 1528 2007-08-20 Threshold effects in catchment storm response and the occurrence and magnitude of flood events: implications for flood frequency D. I. Kusumastuti kusumast@gmail.com I. Struthers M. Sivapalan D. A. Reynolds School of Environmental Systems Engineering, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia Centre for Water Research, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia now at: Departments of Geography & Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 220 Davenport Hall, 607 S. Matthews Avenue, Urbana, Illinois 61801, USA The aim of this paper is to illustrate the effects of selected catchment storage thresholds upon runoff behaviour, and specifically their impact upon flood frequency. The analysis is carried out with the use of a stochastic rainfall model, incorporating rainfall variability at intra-event, inter-event and seasonal timescales, as well as infrequent summer tropical cyclones, coupled with deterministic rainfall-runoff models that incorporate runoff generation by both saturation excess and subsurface stormflow mechanisms. Changing runoff generation mechanisms (i.e. from subsurface flow to surface runoff) associated with a given threshold (i.e. saturation storage capacity) is shown to be manifested in the flood frequency curve as a break in slope. It is observed that the inclusion of infrequent summer storm events increases the temporal frequency occurrence and magnitude of surface runoff events, in this way contributing to steeper flood frequency curves, and an additional break in the slope of the flood frequency curve. The results of this study highlight the importance of thresholds on flood frequency, and provide insights into the complex interactions between rainfall variability and threshold nonlinearities in the rainfall-runoff process, which are shown to have a significant impact on the resulting flood frequency curves. Blöschl, G. and Sivapalan, M.: Process controls on regional flood frequency: coefficient of variation and basin scale, Water Resour Res., 33(12), 2967–2980, 1997. CALM (Department of Conservation and Land Management): Esperance Lakes Nature Reserves. Draft Management Plan for the National Parks and Nature Conservation Authority, Perth, Western Australia, 1997. Chow, V. T., Maidment, D. R., and Mays, L. W.: Applied Hydrology, McGraw-Hill, New York, 1988. Eagleson, P. S.: Dynamics of flood frequency, Water Resour. Res., 8(4), 878–898, 1972. Farmer, D., Sivapalan, M., and Jothityangkoon, C.: Climate, soil, and vegetation controls upon the variability of water balance in temperate and semiarid landscapes: downward approach to water balance analysis, Water Resour Res, 39(2), 1035, doi:10.1029/2001 WR000328, 2003. Fiorentino, M. and Iacobellis, V.: Non-linearity effects in the process of floods generation. Proc. EGS Plinius Conference on Mediterranean Storms, Maratea, Italy, 14–16 October 1999. Gupta, V. K. and Waymire, E.: Scale variability and scale invariance in hydrological regionalization, pp. 88–135, in: Scale Invariance and Scale Dependence in Hydrology, edited by: Sposito, G., New York: Cambridge University Press, 1998. Hipsey, M., Sivapalan, M., and Menabde, M.: The incorporation of risk in the design of engineered catchments for rural water supply in semi-arid Western Australia, Hydrol. Sci. J., 48(5), 709–727, 2003. Huff, F. A.: Time distribution of rainfall in heavy storms, Water Resour. Res., 3(4), 1007–1018, 1967. Pilgrim, D. H. (Ed.): Australia Rainfall and Runoff, The Institution of Engineers Australia, Barton, ACT, 1987. Jothityangkoon, C. and Sivapalan, M.: Temporal scales of rainfall-runoff processes and spatial scaling of flood peaks: Space-time connection through catchment water balance, Adv. Water Resour., 24(9–10), 1015–1036, 2001. Jothityangkoon, C. and Sivapalan, M.: Towards estimation of extreme floods: examination of the roles of runoff process changes and floodplain flows, J. Hydrol.. 281, 206–229, 2003. Kusumastuti, D. I., Reynolds, D., and Sivapalan, M.: Impact of the presence of a network of interconnected lakes within a catchment on flood frequency. Presented at the Seventh IAHS Scientific Assembly, Foz do Iguacu, Brazil, April 3–9, 2005. Ott, R. F. and Linsley, R. K: Streamflow frequency using stochastically generated hourly rainfall, in: International Symposium on Uncertainties in Hydrologic and Water Resources Systems, 1, 230–244, Univ. of Ariz., Tucson, 1972. Robinson, J. S. and Sivapalan, M: An investigation into the physical causes of scaling and heterogeneity of regional flood frequency, Water Resour. Res., 33(5), 1045–1059, 1997a. Robinson, J. S. and Sivapalan, M.: Temporal scales and hydrological regimes: Implications for flood frequency scaling, Water Resour. Res., 33(12), 2981–2999, 1997b. Sivandran, G.: Effect of Rising Water Tables and Climate Change on Annual and Monthly Flood Frequencies. B. Eng. Thesis, Centre for Water Res., Univ. of West. Aus., Crawley, Australia, 2002. Short, R.: A conceptual hydrogeological model for the Lake Warden recovery catchments Esperance, Western Australia. Resource Management Technical Report 200, 2000. Sivapalan, M., Wood, E. F., and Beven, K.: On hydrologic similarity: 3. A dimensionless flood frequency model using a generalized geomorphologic unit hydrograph and partial area runoff generation, Water Resour. Res., 26(1), 43–58, 1990. Sivapalan, M., Blöschl, G., Merz, R., and Gutknecht, D.: Linking flood frequency to long-term water balance: Incorporating the effects of seasonality. Water Resour. Res., 41, W06012, doi:10.1029/2004WR003439, 2005. Spence, C. and Woo, M.-K.: Hydrology of subarctic Canadian shield: soil filled valleys, J. Hydrol., 273, 151–166, 2003. Spence, C. and Woo, M.-K.: Hydrology of subarctic Canadian Shield: heterogeneous headwater basins, J. Hydrol., 317, 138–154, 2006. Struthers, I. and Sivapalan, M.: Conceptual investigation of process controls upon flood frequency: role of thresholds, Hydrol. Earth Sys. Sci., 11, 1405–1416, 2007. Wood, E. F.: An analysis of the effects of parameter uncertainty in deterministic hydrologic models, Water Resour. Res., 12(5), 925–932, 1976.