Large scale experiments for an alternative erosion control measure using sand-filled geosystems. Data set produced at the CIEM flume, Hydralab+

Sand-filled geosystems have the potential to mimic aspects of natural and nature-based features that can enhance the resilience of coastal areas challenged by climate, with additional (structural) reinforcement. Knowledge gaps can be identified. For instance, (i) the sediment transport mechanisms around the geosystem; (ii) the amount of erosion in the leeside when the system is overtopped; (iii) quantitative contribution the geosystem for the wave overtopping reduction; and (iv) failure mechanisms of the geosystem under extreme conditions. Specific tests are proposed in order to fill the defined knowledge gap and answer the following research questions: How do nearshore coastal processes (wave transformation, sediment transport) and wave structure interactions during extreme events differ from those during more usual big storm conditions for situations with and without the geosystem? How do feedbacks between the hydrodynamics and morphology of natural and nature-based features affect flooding, erosion, and recovery of coastal areas when erosion is limited by the 'geosystem'? How to conceive a dynamic coastal protection that can easily adapt to climate change in areas experiencing coastal squeeze (i.e. dense urban environment and human infrastructure with sea encroaching land) and vulnerable to coastal erosion and flooding risks? The set of experiments, done at the large wave Flume (CIEM) in Barcelona, are here described in order to answer the previous questions. These experiments started on October 2018 and ended at the end of November 2018. These tests include different configurations:<br>an initial benchmark tests in order to test the wave conditions were no geosystem protection is used, a second layout with a geotube used as a geosystem protection and finally a third layout were geobags are used as a protection.充砂土工体系（sand-filled geosystem）可模拟天然及仿天然防护设施的部分特性，辅以附加（结构）加固措施后，能够提升受气候胁迫的海岸区域的韧性。 当前仍存在多项认知空白，例如：（1）土工体系（geosystem）周边的泥沙输运机理；（2）体系发生越浪时背风侧的侵蚀量；（3）土工体系对消减波浪越浪的定量贡献；（4）极端工况下土工体系的破坏机理。为填补上述认知空白、解答下述研究问题，本研究提出了针对性试验方案： 1. 在布设与未布设土工体系的工况下，极端事件与常规强风暴期间的近岸海岸动力过程（波浪变形、泥沙输运）及波浪-结构物相互作用存在何种差异？ 2. 当侵蚀过程受“土工体系”约束时，天然及仿天然防护设施的水动力-地貌反馈机制，会如何影响海岸区域的淹没、侵蚀与恢复过程？ 3. 对于面临海岸挤压问题（即海域侵吞陆地所形成的密集城区与人类基础设施区域）且受海岸侵蚀、淹没风险威胁的区域，应如何构建可灵活适配气候变化的动态海岸防护体系？ 为解答上述研究问题，本文详述了于巴塞罗那大型波浪水槽（wave flume，CIEM）中开展的系列试验。该系列试验于2018年10月启动，同年11月末结束。本次试验包含三种不同配置：初始基准试验，用于模拟未布设土工体系防护的波浪工况；采用土工管袋（geotube）作为防护体系的第二组试验；以及采用土工袋（geobag）作为防护体系的第三组试验。