Flood resilience
Further details on the systemic and synthesis for this European Green Deal Criterion are available in the MERLIN Deliverable Report page 53.
Raw data underpinning the analysis are available: DOI: 10.5281/zenodo.17119895
Almost all case studies reported several benefits with respect to improving the situation on flood resilience. Amongst others, many projects provided with increased storage capacity and also newly designated areas for flooding as result of the restoration measures.
Increase in storage capacity
Increase in storage capacity was reported both with respect to restored rivers and streams (Figure 1) and with respect to wetlands (Figure 2).
A very high increase in storage capacity of restored rivers and streams, due to the large spatial scale, was observed for case study CS11 (Emscher basin restoration). A special case is case study CS02 (Deba barrier removal), because due to the measure a loss in storage capacity was noticed. However, this led to a reduction of flood risk upstream, so that overall the measure had a positive outcome. At case study CS03 (Beaver River engineering) the same increase was observed both at the intervention site and the control site. Therefore, it is difficult to assess whether this increase can be attributed to the restoration measure. At case study CS05 (Kampinos wetland rewetting PL) data were elaborated in 8 consecutive years after the restoration measure, which provides with the possibility to study fluctuations regarding this indicator after the implementation.
The highest increase in storage capacity of wetlands showed case study CS10 (Blue Belt Germany), a large-scale project. Case study CS05 (Kampinos wetland rewetting), because of 8 years of data after restoration, provides with the possibility to study fluctuations in the measured values.
Newly designed areas for flooding
Several case studies reported newly designed areas for flooding (Figure 3), with higher values reported by case studies CS05 (Kampinos wetland rewetting), CS09 (Tisza floodplain rewetting) and CS11 (Emscher basin restoration).