Uncertainty analysis of hydrological ensemble forecasts in a distributed model utilising short-range rainfall prediction

Abstract

Abstract. Advances in mesoscale numerical weather predication make it possible to provide rainfall forecasts along with many other data fields at increasingly higher spatial resolutions. It is currently possible to incorporate highresolution NWPs directly into flood forecasting systems in order to obtain an extended lead time. It is recognised, however, that direct application of rainfall outputs from the NWP model can contribute considerable uncertainty to the final river flow forecasts as the uncertainties inherent in the NWP are propagated into hydrological domains and can also be magnified by the scaling process. As the ensemble weather forecast has become operationally available, it is of particular interest to the hydrologist to investigate both the potential and implication of ensemble rainfall inputs to the hydrological modelling systems in terms of uncertainty propagation. In this paper, we employ a distributed hydrological model to analyse the performance of the ensemble flow forecasts based on the ensemble rainfall inputs from a shortrange high-resolution mesoscale weather model. The results show that: (1) The hydrological model driven by QPF can produce forecasts comparable with those from a raingaugedriven one; (2) The ensemble hydrological forecast is able to disseminate abundant information with regard to the nature of the weather system and the confidence of the forecast itself; and (3) the uncertainties as well as systematic biases are sometimes significant and, as such, extra effort needs to be made to improve the quality of such a system.

The COST 731 Action: A review on uncertainty propagation in advanced hydro-meteorological forecast systems

“…In this context Xuan et al (2009) contribute to a better understanding of the implications of the spatial/temporal variability of rainfall forecasts applied in the flood forecasting environment. They used a short-range (24h) ensemble QPF system to produce rainfall forecasts (2 km weather model grid) to drive a distributed rainfall-runoff model (500 m grid size).…”

Development and verification of a real-time stochastic precipitation nowcasting system for urban hydrology in Belgium

“…Since an important fraction of the uncertainty of hydrological predictions is due to the uncertainty of the input rainfall observations and forecasts, radar-based ensemble nowcasting systems are increasingly used as inputs for flood and sewer system modeling (e.g., Ehret et al, 2008;Silvestro and Rebora, 2012;Silvestro et al, 2013;Xuan et al, 2009Xuan et al, , 2014. At longer forecast ranges, the NWP ensembles are also exploited for uncertainty propagation into hydrological models (see Roulin and Vannitsem, 2005;Thielen et al, 2009;Schellekens et al, 2011).…”

Streamflow forecasts from WRF precipitation for flood early warning in mountain tropical areas

“…The significant advances in NWP and computer power during the last decades have led to the generation of high-resolution precipitation forecasts at the catchment scale, and quantitative precipitation forecasts (QPFs) from high-resolution NWPs are increasingly used in flood forecasting systems as a result (Xuan et al, 2009). Particularly for flashy watersheds with short times of concentration, such as those typically found in tropical mountainous watersheds, forecast precipitation is required to provide sufficient forecast lead times in support of timely warnings.…”