Uncertainty of precipitation measurements and predictions in flash flood modelling
- Authors: Mira KOBOLD, Anton ZGONC, Mojca SUŠNIK
- Citation: Acta hydrotechnica, vol. 23, no. 39, pp. 79-98, 2005.
- Abstract: The uncertainty of simulated runoff is mainly the result of precipitation uncertainty associated with the average basin precipitation. Therefore it is very important to assure the accurate precipitation input, whether from raingauges or other sources such as radar measurements or meteorological forecast. The estimation of average basin precipitation from point precipitation measurements is dependent on the catchment scale, density of precipitation network, distribution of precipitation stations and variability of precipitation. In the paper, the unsuitability of the number of recording raingauges on the Savinja catchment for areal estimation of precipitation for flash flood modelling is presented. Point precipitation measurements do not give enough information about areal precipitation which is a base for runoff modelling and simulation. On the other hand, radar provides coverage over a large area with high spatial and temporal resolution. The applicability of radar precipitation was presented for two high water events on the Savinja catchment. For operational flood forecasting the predicted precipitation of meteorological models is input into the rainfall-runoff models. The results of half-yearly runs of HBV-96 model for the Savinja catchment are demonstrated using the meteorological forecast of ALADIN/SI model. The comparison of computed and observed discharges was done separately for the first day and for the second day of forecast. The deviation of the simulated discharge from the measured one is analysed as a result of inaccurate forecast of amount of precipitation on the catchment. The analysis of flash floods, which affected the Posavje region in August 2005, shows the difficulties of flash flood forecasting and early warning issues.
- Keywords: flood forecasting, flash floods, areal precipitation, radar, uncertainty, HBV-96 model, ALADIN/SI model
- Full text: a39mk.pdf