| Volumes and Issues Contents of Issue 4 |
www.hydrol-earth-syst-sci-discuss.net/5/2459/2008/
doi:10.5194/hessd-5-2459-2008
© Author(s) 2008. This work is distributed
under the Creative Commons Attribution 3.0 License.
A space-time hybrid hourly rainfall model for derived flood frequency analysis
1Institute of Water Resources Management, Hydrology and Agricultural Hydraulic Engineering, Leibniz University of Hannover, Hannover, Germany
2Federal Institute of Hydrology, Koblenz, Germany
Abstract. For derived flood frequency analysis based on hydrological modelling long continuous precipitation time series with high temporal resolution are needed. Often, the observation network with recording rainfall gauges is poor, so stochastic precipitation synthesis is a good alternative. Here, a hybrid two step procedure is proposed to provide suitable space-time precipitation fields as input for hydrological modelling. First, a univariate alternating renewal model is presented to simulate independent hourly precipitation time series for several locations. In the second step a multi-site resampling procedure is applied on the synthetic point rainfall event series to reproduce the spatial dependence structure of rainfall. The alternating renewal model describes wet spell durations, dry spell durations and wet spell amounts using univariate frequency distributions separately for two seasons. The dependence between wet spell amount and duration is accounted for by 2-copulas. For disaggregation of the wet spells into hourly intensities a predefined profile is used. In the second step resampling is carried out successively on all synthetic event series using simulated annealing with an objective function considering three bivariate spatial rainfall characteristics. In a case study synthetic precipitation is generated for two mesoscale catchments in the Bode river basin of northern Germany and applied for derived flood frequency analysis using the hydrological model HEC-HMS. The results show good performance in reproducing average and extreme rainfall characteristics as well as in reproducing observed flood frequencies. However, they also show that it is important to consider the same rainfall station network for calibration of the hydrological model with observed data as for application using synthetic rainfall data.
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Citation: Haberlandt, U., Ebner von Eschenbach, A.-D., and Buchwald, I.: A space-time hybrid hourly rainfall model for derived flood frequency analysis, Hydrol. Earth Syst. Sci. Discuss., 5, 2459-2490, doi:10.5194/hessd-5-2459-2008, 2008. Bibtex EndNote Reference Manager XML
