PIONEER: An Adaptation Approach for Resilient Coastal Infrastructure Against Sea Level Rise

自20世纪初以来，英国周围的平均海平面平均每年上升约1.5毫米。在1993-2019年期间，这一比率增加到每年超过3毫米的水平。海平面上升的预测显示，即使在未来气温上升停止的情况下，英国海平面仍将在2100年后继续上升。例如，在低排放情况下，伦敦和加的夫在2300米处的大致预测距离为0.5-2.2米，爱丁堡和贝尔法斯特为0.0-1.7米。在高排放的情况下，伦敦和卡迪夫的这一数字将增加到140万到430万，爱丁堡和贝尔法斯特的这一数字将增加到700万到360万。预计未来极端海平面事件也将变得更加频繁，到2050年，极端海平面事件的发生频率将增加约20到30倍。全球约有1.48亿人面临沿海洪水事件，这种情况将在未来几十年激增。海平面上升还将带来强大的经济后果。例如，保护伦敦所需的投资预计将超过200亿英镑。根据政府间气候变化专门委员会的说法，不可避免的海平面上升将带来连锁和复杂的影响，导致洪水泛滥和对沿海基础设施的破坏，并在短期和长期内对生计、住区、健康、福祉、粮食和水安全构成威胁。有几种已知的方法可以适应海平面上升(例如，调整路线、基于自然的解决方案、软/硬防御)。尽管调整、基于自然的解决方案和软防御提供了成本更低、可持续和弹性更强的解决方案，但在某些情况下，硬防御不可避免地会：坚守阵地。然而，除非将它们纳入一个适应性计划，否则它们在长期内面临的气候风险增加的风险很大程度上取决于了解它们对未来海平面上升和极端事件的反应。海平面上升，以及极端海平面事件的增加，将导致海堤发生海浪漫顶的频率增加。波浪漫顶将对海堤与回填土的相互作用产生重大影响，影响海堤的长期稳定性。海堤能在多大程度上被纳入长期气候变化适应计划，将在很大程度上取决于它们对未来海平面上升和极端海平面事件的反应。为了相应地适应海堤设计，需要从(I)干湿循环和(Ii)侵蚀引起的修改的回填土-海堤相互作用的角度来评估波浪漫顶对海堤整体稳定性的影响。这第一个项目将集中于第一个方面，揭示回填土-海堤相互作用的基本行为，以及由于海浪泛滥而造成的干湿循环。考虑到这个问题的全球性，与学术界、利益攸关方和行业合作伙伴共同寻找解决方案至关重要。因此，该项目将是启动赫里奥特·瓦特大学(HWU)和美国弗吉尼亚理工大学(VT)之间国际合作的第一步。这项研究工作的主要好处将是(I)沿海人口，(Ii)英国经济和(Iii)农业土地和文化价值。

Mean sea level around the UK has risen by approximately 1.5 mm per year on average from the start of the 20th century. This rate has increased to levels exceeding 3 mm per year for the period 1993-2019. The projections of sea level rise show that UK sea level will continue to rise well beyond 2100, even under scenarios where future temperature rise is stopped. For instance, under a low emissions scenario, the approximate projected ranges at 2300 are 0.5 - 2.2 m for London and Cardiff, and 0.0 - 1.7 m for Edinburgh and Belfast. Under a high emissions scenario, this increases to 1.4 - 4.3 m for London and Cardiff, and 0.7 - 3.6 m for Edinburgh and Belfast. Extreme sea level events are also expected to become more frequent in the future and occurring about 20 to 30 times more frequently by the year 2050.Around 148 million people are exposed to coastal flooding events worldwide, which will surge in the coming decades. Rising sea level will also have strong economic consequences. For instance, the investment required to protect London is expected to exceed 20 billion GBP. According to IPCC, unavoidable sea level rise will bring cascading and compounding impacts resulting in flooding and damages to coastal infrastructure that cascade into risks to livelihoods, settlements, health, well-being, food, and water security in the near to long-term.There are several known approaches to adapt to sea level rise (e.g., realignment, nature-based solutions, soft/hard defences). Although realignment, nature-based solutions and soft defences provide lower cost, sustainable and resilient solutions, there are cases where hard defence is unavoidable to: hold the line. Yet, they have the risk of increased exposure to climate risks in the long-term unless they are integrated into an adaptive plan, which strongly relies on understanding their response to future sea level rise and extreme events.The sea level rise, along with the increase of the extreme sea level events, will lead to increased frequency of wave overtopping at the seawalls. Wave overtopping will have significant impact on the interaction of the wall with the backfill soil, affecting the stability of the seawalls in the long-term. The extent to which the seawalls can be integrated as a part of the long-term climate change adaptation plans will depend substantially on their response to future sea level rise and extreme sea level events.To adapt the seawall design accordingly, the impact of wave overtopping on the overall stability of seawalls need to be evaluated in terms of modified backfill soil-seawall interaction due to (i) wetting-drying cycles and (ii) erosion. This first project will focus on the first aspect, unlocking the fundamental behaviour of backfill soil-seawall interaction to wetting-drying cycles due to wave overtopping.Considering the global nature of the problem, an international collaboration is of paramount importance to find a mutual solution with academics, stakeholders and industry partners. Thus, this project will be a first step to initiate international collaboration between Heriot Watt University (HWU) and Virginia Tech (VT), USA.The main benefits of this research work will be on (i) coastal population, (ii) UK economy and (iii) agricultural land and cultural values.