Integrated Flood Risk Management

Integrated flood risk management aims to reduce risks in advance, for example through spatial planning measures, awareness-raising, or disaster protection plans. The priority of such non-structural measures over technical flood protection measures has been established in Austria, based on the EU Floods Directive, in national legal requirements and technical guidelines. There is still research and improvement potential in the process understanding of flood events, the communication and representation of protection goals, and the handling of remaining residual risks. The maintenance of watercourse space and the creation of flood and retention areas must be intensified. In the area of technical flood protection, in addition to the further implementation of planned public flood protection measures (closing gaps), the recording and condition monitoring of existing protection measures should also be pursued.

Flood Risk Cycle
Following flood protection, the EU Floods Directive was adopted in the aftermath of the extreme floods in 2002 and incorporated into national law. Moreover, it became clear that there is no such thing as absolute flood protection, and instead, the flood risk must be considered. This includes both the danger posed by “too much water” and the resulting damage. At the same time, it is necessary to consider disaster response, immediate measures during an event, the restoration of livelihoods, flood prevention, and flood preparedness in an integrated manner.

At the IWA (Institute of Hydraulic Engineering and River Research), research is conducted on all components. These include model experiments on innovative protection measures as well as trials related to emergency organizations.

Active and Passive Measures to Reduce Flood Risk

In the field of active, structural measures to reduce flood risk, research is conducted in the hydraulic engineering laboratory on flood protection embankments, retention basins, linear measures, mobile flood protection, and the importance of ecological watercourse development.

Passive measures include spatial planning improvements at the strategic level, as well as studies on the importance of vegetation and its management.

Extreme Events under Climate Change and Land Use Change and their Impacts

Climate change and land use change lead to an increase in extreme events and a rise in damages. BOKU (University of Natural Resources and Life Sciences, Vienna) research deals with adaptation to these changes. This includes, among other things, the question of the sizing of structures and their interaction with anthropogenic uses.

Role of Sediment Transport, Solid Matter Budget, and River Morphology

A focus of research in the hydraulic engineering laboratory encompasses the role of sediment transport, solid matter budget, and river morphology, as the rivers in Austria and beyond have been greatly altered and often suffer from deficits or surpluses. This can lead, for example, to an increased risk of faults or aggradations as well as more severe flooding in the case of riverbed deepening.

Large-scale experiments enable the development of principles for designing more resilient rivers in terms of gradient, width, and sediment input.

Conservation and Improvement of Floodplains
The loss of floodplains demonstrably leads to an intensification of the flood wave in terms of peak discharge, duration, and water level. At the IWA (Institute for Water Resources Management, Hydrology and Hydraulic Engineering), for instance, the Floodplain Evaluation Matrix was developed, which allows for an objective assessment of the importance of these areas and thus creates a basis for their evaluation and improvement.

Drift Hazard for Individuals and Emergency Organizations
Unfortunately, there are always fatalities during flood events – among both affected individuals and emergency personnel. Experiments on the drift hazard of persons in the hydraulic engineering laboratory enable the determination of threshold values concerning water depth and flow velocity as a basis for hazard zone planning.

For emergency organizations, there is the opportunity to conduct training, gather experience for real-life situations, and receive specific recommendations for action to minimize the risk during operations.

Awareness Raising and Citizen Science

Projects in the field of flood risk management include the development of measures to increase awareness of the dangers. Innovations are also found in the context of Citizen Science, to obtain more data for flood analysis.

Impacts of Climate Change on Low Water Levels in Flowing Waters

The impacts of climate change are increasingly evident in relation to low water levels in flowing waters, creating problems for navigation, hydropower, and ecology.
BOKU research is developing measures to improve the low water situation, including by improving morphology or the interaction between river water and groundwater.

Change in Water Temperature

Over the last 30 years, the water temperature, for example in the Danube, has risen by up to 2 degrees Celsius, which has effects on possible cooling water extraction as well as ecology (e.g., reduced oxygen content). In addition to analyzing temperature changes, research also focuses on the effects of shading by vegetation or the importance of groundwater infiltration into the flowing water.

Role of Flowing Waters and Floodplains in Minimizing Drought Risk

Flowing waters and floodplains are of great importance for minimizing the risk of drought, as, for example, groundwater recharge is possible through overflow during higher discharges, or there is water retention in the area. Research quantifies these processes as well as the positive effects of improvement measures in the area of watercourse structure and the foreland.

Importance of River Morphology for Low Water Levels

A variable and dynamic river morphology results, for example, in higher water depths at low water levels, thus providing habitats for fish and generally for ecology, as well as an increase in the exchange areas between river water and groundwater. Analyses of these processes form the basis for later measures and planning.

Development of Measures for Water Retention During Droughts

Research on water retention measures is gaining importance with the increasing impact of climate change and involves both structural and non-structural measures. Corresponding studies lead to innovative measures that also represent win-win solutions. This means that measures, for example, can reduce both flood risk and drought risk at the same time.