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River flood Embankments Subject to Climate change: Understanding Effects of future floods and novel ‘low-carbon’ adaptation measures

Final Report Summary - RESCUE (River flood Embankments Subject to Climate change: Understanding Effects of future floods and novel ‘low-carbon’ adaptation measures)

The consequences of climate change are increasingly being felt in Europe and worldwide. The average global temperature continues to rise and some natural processes are being altered, e.g. precipitation patterns are changing and glaciers are melting. The impact of climate change will increase in the coming decades because of the delayed impacts of past and current greenhouse gas emissions. Climate change has already a tangible impact on flood risk. Between 1980 and 2011, direct economic losses in the EU due to flooding amounted to more than €90 billion. This amount is expected to increase, as the annual cost of damage from river floods is estimated at €20 billion by the 2020s and € 46 billion by the 2050s. The social cost of climate-induced floods can also be significant. Floods in the EU resulted in more than 2500 fatalities and affected more than 5.5 million people over the period 1980-2011.

Adaptation measures to address flood risk are a priority at European level. Flood defence embankments are and will remain the major asset in a flood defence system and they are therefore one of the major focus of flood risk management agencies. Key steps in the adaption process are
i) Assessing hazard of embankment failure
ii) Identifying adaptation options.

Hydro-mechanical models for the stability flood river embankments subject to flood are traditionally based on the assumptions of steady-state through-flow and zero pore-pressures above the phreatic surface, i.e. negative capillary pressures (suction) are ignored. RESCUE aims to introduce a stepchange in the approach to the assessment of embankment stability by considering more realistic transient flow conditions establishing upon a flood and taking into account the effects of suction on the hydro-mechanical response of the embankment. This allows for flood duration, antecedent flood, and antecedent precipitation incident to the embankment to be taken into account.

The aim of the RESCUE project is to develop an approach to assess the impact of climate-induced floods on stability of existing river flood embankments, at both local and regional scale, and to explore low-carbon remedial adaptation measures. The approach includes strategies for geotechnical characterisation assisted by field monitoring, real-time monitoring to support emergency management, and ‘accessible’ tools for numerical modelling of the embankment stability conditions.
Adaptation strategies are centred on the concept of suction-reinforced flood embankments, i.e. suction is considered an untapped natural reinforcement that can be successfully exploited to strengthen the embankments. In this respect, vegetation is considered a remedial measure in the sense that it promotes the generation of suction via evapotranspiration.
The approaches developed by RESCUE were validated against the case study of the Adige River embankment made available by the Agency for Civil Protection in Bolzano, Italy.