A framework for downscaling precipitation from RCM projections to the high resolutions in time and space required in the urban hydrological climate change impact assessment is outlined and demonstrated. The basic approach is that of Delta Change, developed for both continuous and event-based applications. In both cases, Delta Change Factors (DCFs) are calculated which represent the expected future change of some key precipitation statistics. In the continuous case, short-term precipitation from climate projections are analysed in order to estimate DCFs associated with different percentiles in the frequency distribution of non-zero intensities. The DCFs may then be applied to an observed time series, producing a realisation of a future time series. The event-based case involves downscaling of Intensity-Duration-Frequency (IDF) curves based on extreme value analysis of annual maxima using the Gumbel distribution. The resulting DCFs are expressed as a function of duration and frequency (i.e., return period) and may be used to estimate future design storms. The applications are demonstrated in case studies focusing on the expected changes in short-term precipitation statistics until 2100 in the cities of Linz (Austria) and Wuppertal (Germany). The downscaling framework is implemented in the climate service developed within the EU-project SUDPLAN. Full article

A new flexible, rapid and affordable risk assessment procedure was developed and verified for dams based on case studies in Scotland (UK) and the region of Baden (Germany). A database of six different sustainable flood retention basin (SFRB) types with varying flood control potential has been developed. In Scotland, there are a relatively high number of current and former large drinking water reservoirs which could contribute to flood management control. In comparison, purpose-built and relatively small SFRB, which are predominantly used for flood control, dominate the landscape in Baden. Moreover, 13 out of 149 SFRB have recently been upgraded, and 11 new SFRB have been built since 2006. Both the estimated hazard and risk are small in comparison to those found in the flood infrastructure in Scotland. The study assesses a rapid screening tool developed to estimate the Dam Condition and the corresponding Dam Failure Hazard and Dam Failure Risk. Most SFRB in Baden have a relatively poor Dam Condition, high Dam Failure Hazard but low Dam Failure Risk compared to those in Scotland. Findings show that Baden is more advanced in flood defence management as well as adaptation to climate change.

Deutscher Titel: Neue Methode zur Beurteilung des Risikos eines Dammbruches
Zusammenfassung: Eine neue, flexible, schnelle und preisgünstige Methode zur Risokobeurteilung von Dämmen wurde entwickelt und getestet, die auf Fallbeispielen in Schottland (Vereinigtes Königreich) und der Region Baden (Deutschland) basiert. Eine Datenbank von sechs verschiedenen Typen nachhaltiger Hochwasserrückhaltebecken (NHRB) mit unterschiedlichem Hochwasserrückhaltevermögen wurde entwickelt. Eine relativ hohe Anzahl von gegenwärtigen und ehemaligen großen Trinkwassertalsperren, die zur Hochwasserschutzkontolle verwandt werden könnten, befinden sich in Schottland. Zweckmäßig gebaute und relativ kleine NHRB, die hauptsächlich für den Hochwasserschutz verwendet werden, dominieren hingegen die Landschaft in Baden. Darüber hinaus wurden 13 von 149 NHRB kürzlich renoviert und seit 2006 wurden 11 neue NHRB gebaut. Sowohl die geschätzte Gefahr als auch das Risiko sind im Vergleich zu den Parametern, die für die Hochwasserschutzinfrastruktur in Schottland gefunden worden sind, klein. Die Studie untersucht ein zeitsparendes Instrument zur Beurteilung des Dammzustandes, der Dammbruchgefahr und des Dammbruchrisikos. Die meisten NHRB in Baden haben relativ geringe Werte bezüglich des Dammzustandes, hohe Werte für Dammbruchgefahr und niedrige Werte bezüglich des Dammbruchrisikos im Vergleich zu NHRB in Schottland. Die Ergebnisse zeigen, dass Baden im Hochwasserschutz vorne liegt und daher dem Klimawechsel besser angepasst ist. Full article

During recent years, a great deal of attention has been focused on the financial risk management of natural disasters. One reason behind is that the economic losses from floods, windstorms, earthquakes and other disasters in both the developing and developed countries are escalating dramatically. It has become apparent that an integrated water resource management approach would be beneficial in order to take both the best interests of society and of the environment into consideration. One improvement consists of models capable of handling multiple criteria (conflicting objectives) as well as multiple stakeholders (conflicting interests). A systems approach is applied for coping with complex environmental and societal risk management decisions with respect to flood catastrophe policy formation, wherein the emphasis is on computer-based modeling and simulation techniques combined with methods for evaluating strategies where numerous stakeholders are incorporated in the process. The resulting framework consists of a simulation model, a decision analytical tool, and a set of suggested policy strategies for policy formulation. The framework will aid decision makers with high risk complex environmental decisions subject to significant uncertainties. Full article