HR: 1340h
AN: H33E-1420    [Abstracts]
TI: Floods as a mixed-physics phenomenon: Statistics and Scaling
AU: * Theodoratos, N
EM: theo0033@umn.edu
AF: St Anthony Falls Laboratory, University of Minnesota, 2 3rd Ave SE, Minneapolis, MN 55414 United States
AU: Foufoula-Georgiou, E
EM: efi@umn.edu
AF: St Anthony Falls Laboratory, University of Minnesota, 2 3rd Ave SE, Minneapolis, MN 55414 United States
AB: Past studies have shown some distinctive characteristics of floods (maximum annual flows), namely two different scaling regimes with a scaling-break at a characteristic scale. For Midwestern alluvial streams this scale was argued to correspond to the transition from mostly erosional to mostly depositional fluvial regimes. Closer examination of maximum annual flood series shows that it is composed of two distinct populations, one from below bank-full flows and the other from above bank-full (floodplain) flows. The frequency of bank-full discharge is not constant along scales and therefore the contribution of each population to the overall series is scale dependent. Acknowledging these facts, extreme floods can be seen as a mixed-physics phenomenon with a scale-dependent mixing. Thus the current methodologies for inferring statistical scaling in floods should be applied and interpreted with caution. In this study we try to gain insight on the scaling of floods, by studying separately the scaling of each population, and quantifying the relative effect of the scale-dependent mixing and the geomorphologically imposed scaling break on the statistics and scaling of the whole mixture. The analysis is done by simulation due to lack of long records of maximum annual floods and in order to quantify the effects as a function of sample size. We find that some observed characteristics of floods (apparent absence of scaling, extended self similarity, etc) can be explained as reflections of the above physical properties of floods and call for a revised physical-statistical formalism of scaling in floods.
DE: 1821 Floods
DE: 1839 Hydrologic scaling
DE: 1869 Stochastic hydrology
DE: 4475 Scaling: spatial and temporal (1872, 3270, 4277)
SC: Hydrology [H]
MN: Fall Meeting 2005