The World's Biggest Flood Defence Megaprojects

This section delves into the struggle of Venice against flooding and rising sea levels. Despite the implementation of a $7 billion sea defense system called MOSE, which began operating in 2020, Venice continues to face significant flooding challenges. The system, consisting of metal barriers placed around the lagoon's inlets, was designed to protect the city but has proven insufficient in keeping areas like St. Mark's Square dry, leading to the adoption of additional measures such as glass barriers. The MOSE project, plagued by delays and evolving climate change predictions, is now seen as outdated, with parts of the city still experiencing flooding. This situation underscores the complex and ongoing battle against rising waters in Venice.

The narrative continues with the limitations of Venice's MOSE system, which is only activated when tides are expected to rise above 110 cm, protecting approximately 86% of the city. This threshold is set to avoid frequent closures that the system isn't designed to handle, leading to the continued use of temporary measures like glass barriers. The operational costs of MOSE, requiring a large team for manual management, contribute to its infrequent use. Despite still being in an experimental phase, with hopes for future optimization, the system faces criticism for not fully addressing the city's needs, prompting discussions on alternative, long-term solutions such as raising the city's foundation.

This section explores China's response to urban flooding through the development of 'sponge cities.' With over 100 cities facing the challenges of heavy storms and flooding due to rapid urbanization, China is incorporating nature-based solutions alongside traditional infrastructure. The 'sponge city' concept aims to absorb, store, and reuse rainwater through a combination of green (natural) and gray (engineered) infrastructure. Projects in cities like Chongqing and Zhengzhou demonstrate significant progress in managing rainwater, but the effectiveness of these solutions against severe storms remains a concern. Despite the challenges, sponge cities represent a proactive and ecological approach to urban water management in China.

The narrative further details China's sponge city initiative, highlighting specific projects and their impacts. Chongqing's new park and Zhengzhou's bioswales exemplify the practical implementation of sponge city principles, showcasing efforts to manage stormwater and enhance urban resilience. However, the devastating flood in Zhengzhou in 2021 raised questions about the effectiveness of these initiatives during extreme weather events. Despite these challenges, the sponge city approach remains a key strategy for China, aiming to balance urban development with environmental sustainability.

This section describes Copenhagen's innovative solution to its growing population and flooding concerns through the construction of a new artificial island, Lynetteholm. The project, costing about $3 billion, aims to provide surge protection and additional housing space by adding 2.6 square km of land to the port area. The island will feature natural defenses like rock dams and green landscapes, and it's expected to accommodate around 35,000 residents once completed. Despite its potential benefits, the project has faced criticism regarding environmental impact, traffic congestion, and its approach to affordable housing.

This section focuses on New York City's initiatives to combat the effects of climate change, particularly in Battery Park City, which is vulnerable to flooding and sea level rise. A $220 million plan proposes the construction of a seawall, flood barriers, and the elevation of Wagner Park to protect key areas in Lower Manhattan. While the project promises to enhance the city's resilience against future storms, it has faced opposition from local advocates concerned about the reduction of green space and the potential impact on community accessibility.

The narrative concludes with Texas's large-scale coastal defense project, known as the 'Ike Dike,' designed to protect the Galveston-Houston area from future hurricanes and storm surges. Inspired by Dutch engineering, the project includes a comprehensive system of gates, barriers, man-made beaches, and ecological restoration, with an estimated cost of $31 billion. While ambitious in scope and scale, the project faces challenges in funding and implementation, highlighting the complex interplay between infrastructure development and environmental protection in addressing climate change impacts.