Abstract
Abstract. In recent years, the Free State of Saxony (Eastern Germany) was repeatedly hit by both extensive riverine flooding, as well as flash flood events, emerging foremost from convective heavy rainfall. Especially after a couple of small-scale, yet disastrous events in 2010, preconditions, drivers, and methods for deriving flash flood related early warning products are investigated. This is to clarify the feasibility and the limits of envisaged early warning procedures for small catchments, hit by flashy heavy rain events. Early warning about potentially flash flood prone situations (i.e., with a suitable lead time with regard to required reaction-time needs of the stakeholders involved in flood risk management) needs to take into account not only hydrological, but also meteorological, as well as communication issues. Therefore, we propose a threefold methodology to identify potential benefits and limitations in a real-world warning/reaction context. First, the user demands (with respect to desired/required warning products, preparation times, etc.) are investigated. Second, focusing on small catchments of some hundred square kilometers, two quantitative precipitation forecasts are verified. Third, considering the user needs, as well as the input parameter uncertainty (i.e., foremost emerging from an uncertain QPF), a feasible, yet robust hydrological modeling approach is proposed on the basis of pilot studies, employing deterministic, data-driven, and simple scoring methods.
Highlights
For Saxony, considering the last two decades, the hydrologically most intense and most disastrous events occurred in August 2002, August/September 2010, as well as June 2013 (LfULG, 2015)
As the authority responsible for operational flood forecasting and warning, the Saxon Flood Center drafted a corresponding project with a preferably holistic view on flood risk management procedures, especially, when it comes to smallscale and flashy events
User demands, driving data, and hydrologic modeling techniques were evaluated within a real-word application context in order to illustrate a way towards a flash flood early warning strategy formesoscale catchments in Saxony
Summary
For Saxony, considering the last two decades, the hydrologically most intense and most disastrous events occurred in August 2002, August/September 2010, as well as June 2013 (LfULG, 2015). In August/September 2010, flashy events caused large parts of total damages. In this light, the Saxon State Government mandated an independent commission to make suggestions for improving flood risk management actions (Jeschke et al, 2010). One of the commission’s recommendations was to line out the potentials and limits of small-scale flash flood early warning approaches (i.e., based on hydrological forecasts). As the authority responsible for operational flood forecasting and warning, the Saxon Flood Center drafted a corresponding project with a preferably holistic view on flood risk management procedures, especially, when it comes to smallscale and flashy events. A threefold approach is proposed, aiming at (1) the assessment of the demands and requirements of potential users of early warning products; (2) the verification of driving meteorological data for the targeted spatio-temporal scales; (3) checking the usefulness of a preferably broad range of modeling approaches with regard to model skill, robustness, and regional applicability, for Published by Copernicus Publications on behalf of the International Association of Hydrological Sciences
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