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: 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. 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). WW3 time series of wave parameters (wave height, peak period, & direction) for 8 stations in the Emilia-Romagna coastal belt (2010-19, present climate). 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). WW3 time series of wave parameters (wave height, peak period, & direction) for 8 stations in the Emilia-Romagna coastal belt (2040-49, future climate). 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).

本研究依托面向环境风险管理的基于自然的解决方案露天实验室（OPEn-air laboRAtories for Nature baseD solUtions to Manage environmental risks，缩写OPERANDUM）项目，提出了海草NBS（基于自然的解决方案，Nature-based Solutions）的模拟设计方法体系：该体系将当前及未来气候下经过验证的海浪数值模拟结果，与加入海草植被后的修正海浪模拟结果进行对比分析。
本研究采用MedCORDEX风场（基于RCP8.5排放情景），针对艾米利亚-罗马涅（Emilia-Romagna）沿岸海域，分别开展了2010-2019年（当前气候时段）与2040-2049年（未来气候时段）的WWIII（WAVEWATCH III）数值模拟，以生成对应时段的海浪气候态数据集。
研究对WWIII模式进行了适配性修正，加入了由淹没型水生植被引发的底摩擦耗散应力项，从而将NBS4作为海浪振幅削减的潜在调控机制纳入模型框架。本研究选取鳗草（Zostera marina）作为模拟物种，首先在WWIII模式中布设了沿岸海草带，并开展敏感性模拟试验，以评估贝洛基奥海滩（Bellocchio beach）不同海草景观设计方案的影响效果。
针对当前与未来气候时段，分别设置了有无海草（NBS4）的对照模拟试验组。
基于上述模拟结果，研究发现海草景观设计是植被参与海浪调控数值模拟中的关键环节。相较于其他景观设计方案，破碎化植被条带与斑块的组合形式，可有效削减近岸海域的海浪能量。
对贝洛基奥海滩有无植被场景下的有效波高（Hs）对比分析显示，在当前与未来气候时段的高波能区间内，海浪高度均出现显著降低。沿岸海草带的海浪衰减率存在显著季节周期性：冬季衰减率较高，夏季则相对较低。相较于当前气候情景，未来气候场景下的平均衰减率将略有提升。
整体而言，应用于艾米利亚-罗马涅沿岸海域的鳗草海草带可有效削减海浪能量，衰减率超过50%。本研究的局限性在于仅采用了刚性海草的参数化方案，未来将开展柔性海草的高级参数化相关研究。
本数据集包含OAL-ITALY区域的海浪模式输出数据，具体包括：
1. 模式域水深地形数据；
2. 当前（2010-2019年）与未来（2040-2049年）气候时段的平均有效波高（Hs，单位：米）空间分布图；
3. 贝洛基奥海滩海草带位置分布图；
4. 有无植被场景下的有效波高时间序列对比数据；
5. 海浪衰减空间分布图；
6. 2010-2019年（当前气候时段）艾米利亚-罗马涅沿岸海域8个监测站位的时间序列数据（含站位分布图），用于海浪参数（有效波高、峰值周期与传播方向）的分析；
7. 2010-2019年（当前气候时段）艾米利亚-罗马涅沿岸海域5个监测站位的有无植被场景下有效波高时间序列对比数据（含站位分布图）；
8. 2040-2049年（未来气候时段）艾米利亚-罗马涅沿岸海域8个监测站位的海浪参数（有效波高、峰值周期与传播方向）WWIII模拟时间序列数据；
9. 2040-2049年（未来气候时段）艾米利亚-罗马涅沿岸海域5个监测站位的有无植被场景下有效波高（Hs，单位：米）WWIII模拟时间序列数据。