TY - JOUR
T1 - Towards probabilistic forecasting of flash floods
T2 - The combined effects of uncertainty in radar-rainfall and flash flood guidance
AU - Villarini, Gabriele
AU - Krajewski, Witold F.
AU - Ntelekos, Alexandros A.
AU - Georgakakos, Konstantine P.
AU - Smith, James A.
N1 - Funding Information:
The first author was supported by NASA Headquarters under the Earth Science Fellowship Grant NNX06AF23H while a graduate student at the University of Iowa. The authors wish to thank two anonymous reviewers and the associate editor Dr. Marco Borga for their helpful comments.
PY - 2010/11/17
Y1 - 2010/11/17
N2 - The flash flood guidance system (FFGS) is an operational system which assists forecasters to issue flash flood warnings and watches over the conterminous United States. Currently, it is a deterministic system: given a specified precipitation accumulation over a basin and over a time period, issuing of flash flood watches and warnings is considered depending on the exceedance of a certain threshold value (flash flood guidance - FFG). For given channel characteristics and initial soil moisture conditions, FFG values are computed with the use of a hydrologic model. The purpose of this study is to consider the effects of radar-rainfall and flash flood guidance uncertainties on the FFGS. The errors in the FFG are accounted for by quantifying the uncertainties due to the estimation of the hydraulic and terrain characteristics, and the hydrologic model parameters and initial state. To account for the uncertainties in radar-rainfall, the authors use an empirically-based radar-rainfall error model. This model requires calibration for each application region and it accounts for range effects, synoptic conditions, space-time resolutions, and the spatial and temporal dependences of the errors. Thus, the combined effects of uncertainty in both radar-rainfall and FFG can be assessed. The results are exemplified through two cases in a small basin in the Illinois River Basin. The potential of transforming FFGS into a probabilistic system is also discussed.
AB - The flash flood guidance system (FFGS) is an operational system which assists forecasters to issue flash flood warnings and watches over the conterminous United States. Currently, it is a deterministic system: given a specified precipitation accumulation over a basin and over a time period, issuing of flash flood watches and warnings is considered depending on the exceedance of a certain threshold value (flash flood guidance - FFG). For given channel characteristics and initial soil moisture conditions, FFG values are computed with the use of a hydrologic model. The purpose of this study is to consider the effects of radar-rainfall and flash flood guidance uncertainties on the FFGS. The errors in the FFG are accounted for by quantifying the uncertainties due to the estimation of the hydraulic and terrain characteristics, and the hydrologic model parameters and initial state. To account for the uncertainties in radar-rainfall, the authors use an empirically-based radar-rainfall error model. This model requires calibration for each application region and it accounts for range effects, synoptic conditions, space-time resolutions, and the spatial and temporal dependences of the errors. Thus, the combined effects of uncertainty in both radar-rainfall and FFG can be assessed. The results are exemplified through two cases in a small basin in the Illinois River Basin. The potential of transforming FFGS into a probabilistic system is also discussed.
KW - Flash flood
KW - Flash flood guidance
KW - Radar-rainfall
KW - Uncertainties
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U2 - 10.1016/j.jhydrol.2010.02.014
DO - 10.1016/j.jhydrol.2010.02.014
M3 - Article
AN - SCOPUS:77957557856
SN - 0022-1694
VL - 394
SP - 275
EP - 284
JO - Journal of Hydrology
JF - Journal of Hydrology
IS - 1-2
ER -