Emilia-Romagna coastal area NBS (OAL ITALY) for storm surge mitigation

Within the framework of the OPEn-air laboRAtories for Nature baseD solUtions to Manage environmental risks (OPERANDUM) project, the seagrass NBS is presented within a simulation design methodology consisting of the comparison between validated wave numerical simulations for the present/ future climate, and modified wave simulations with marine seagrass. Ten years of WWIII simulations have been executed to generate the wave climatology, particularly over the Emilia-Romagna coastal strip for the present (2010-19) and future climate (2040-49) using MedCordex winds (based on RCP8.5). The WWIII model was modified to include a modified bottom dissipation stress due to submerged vegetation, thereby incorporating the NBS4 as a potential mechanism for wave amplitude reduction. The seagrass species ‘Zostera marina’ was chosen in this study and an along-shore seagrass belt was first inserted in WWIII and sensitivity experiments were carried out to assess the effects of different types of seagrass landscape designs in the Bellocchio beach. Simulation experiments with and without seagrass (NBS4) were carried out for the present and future climates. Based on the present and future climate simulations, it is noted that the seagrass landscaping is an important aspect in the numerical modelling of vegetation. A combination of broken vegetation stripes and clusters were seen to be effective in reduction of wave energy at the coast in comparison to other landscape designs. The wave height comparisons in the Bellocchio beach, with and without vegetation showed a considerable reduction in wave heights specifically in the higher ranges for both the present and future climates. There exists a strong seasonality in the attenuation rates along the coastal belt with higher attenuations during winter and comparatively lower in summer. In comparison to the present climate, a slightly increased rate of mean attenuation is expected in the future scenarios. Overall, the Zostera Marina seagrass applied for the Emilia-Romagna coastal belt was found to be efficient in reduction of wave energy (> 50%). The limitation being that the experiments were done with rigid seagrass and in the future, we look for advanced parameterization using flexible seagrass.

This dataset contains wave model outputs for the OAL-ITALY, mainly:

1. Bathymetry of the model domain, Spatial maps of mean significant wave height (Hs in m) for present (2010-19) and future climate (2040-49), Seagrass belt position in the Bellocchio beach, Time-series comparison of Hs, with & without vegetation, and Wave attenuation maps.

2. Selected locations (station map) for the time series in the Emilia-Romagna coastal belt during the period 2010-19, and 2040-49 (8 stations), Selected locations (station map) in the Emilia-Romagna coastal belt for the time series comparison (with and without vegetation) during the period 2010-19, and 2040-49 (5 stations).

3. WW3 time series of wave parameters (wave height, peak period, & direction) for 8 stations in the Emilia-Romagna coastal belt (2010-19, present climate).

4. WW3 time series of significant wave height (Hs in metres) with and without vegetation for 5 stations in the Emilia-Romagna coastal belt (2010-19, present climate).

5. WW3 time series of wave parameters (wave height, peak period, & direction) for 8 stations in the Emilia-Romagna coastal belt (2040-49, future climate).

6. WW3 time series of significant wave height (Hs in metres) with and without vegetation for 5 stations in the Emilia-Romagna coastal belt (2040-49, future climate).