Coastal cities have always been a point of attraction for residents, tourists, and businesses. Alongside the aesthetic features, their proximity to the sea has made these cities a focal point for maritime transportation with the construction of ports, as well as hotspots for recreational and aquacultural activities. However, the past decades saw these particular regions threatened with a shortened lifespan; rising water levels, floods, and recurring cyclones, along with other natural disasters, have endangered coastal communities, putting their population, ecosystem, and built environment at risk.
Earlier this month, the Intergovernmental Panel on Climate Change (IPCC), the United Nation's body for assessing the science related to climate change, addressed the current and anticipated impacts of climate change on ecosystems and human communities across the globe, explaining that if governing bodies did not make prompt changes, the world would reach an "irreversible" state. Evidently, towns and settlements built in geographically-challenged zones were proven to be the most vulnerable to the repercussions of climate change, particularly those built by the sea, ocean, or rivers. Although they face the highest risks, coastal cities are home to 11% of the world’s population, serving as a focal point to most of the world’s economic activities, critical infrastructure, and attractive hotspots for tourists as well. 896 million people live in low-lying coastal cities that are in direct exposure to coastal hazards, meaning that these individuals, along with their houses, businesses, and communities, will eventually cease to exist following the accelerating impacts of climate change.
The report expects that by 2050, many cities by the sea will face severe disruption to their coastal ecosystems as a result of heat waves, droughts, pluvial floods, tropical cyclones, marine and land heatwaves, and ocean acidification. It is expected that within the next few years, 36 cities, including Tokyo, Mumbai, New York, Istanbul, Bangkok, London, and Sydney, will be the first to be heavily impacted by rising sea levels. Last year, the World Heritage Committee decided to strip Liverpool of its heritage status, as its new urban developments are considered detrimental to the waterfront's integrity. To avoid having the same fate as Liverpool, Venice, a city that has been battling rising water levels and floods for centuries, has announced the permanent ban of large cruise ships in the Venetian lagoon, after several years of protests, petitions, and threats of being put on UNESCO’s endangered list.
The IPCC provided a series of recommended interventions to manage coastal risks and build resilience over time, some of which are a mix of infrastructural, nature-based, institutional and socio-cultural interventions to reduce the multifaceted risks facing these urban communities. These interventions include vulnerability reducing measures, avoidance, hard- and soft-protection, implementing integrated multi-level coastal zone governance, pre-emptive planning, and enabling behavioral change. An adaptation pathways planning approach is critical to understand how the solution space can expand or shrink based on the type and timing of interventions. For instance, in areas where sufficient space and adequate habitats are available, nature-based solutions can help to reduce coastal hazard risks and provide complimentary benefits, however biophysical limits may be reached before the end of the century.
As the climate deteriorates, many initiatives have already been put in place by governments and NGO’s to maintain coastal communities. Looking beyond large-scale engineering solutions such as constructing banks and flood walls, the “Sponge City" approach uses nature itself as a planning system, where rivers and canals are integrated with trees, parks, and forests to create a natural infrastructure. Instead of using concrete to build a rainwater channel that redirects the water elsewhere, the land absorbs the excess water like a sponge, and uses it to cultivate the land. Sponge cities can be heavily seen in China, such as in the port city of Ningbo, where a 3km strip of brownfield was transformed into an eco-corridor and public park. Similarly, Shanghai has transformed its “Land of Starry Sky” park into a sponge facility, using permeable materials to absorb rainwater.
Another response for reducing vulnerability in coastal zones is the Blue Urban Agenda. Taking into account how the two typically-employed paradigms: the Brown Agenda (social justice in post-industrial areas) and Green Agenda (protection of urban ecosystems), overlook the marine ecosystem, governments are opting for a Blue Urban Agenda. This agenda recognizes the dichotomy and constant exchange between land and sea, and highlights how flooding goes beyond the shoreline. The program allows cities to shape the coastline and ocean/sea by implementing building codes in urban planning, integrating coastal setbacks, and constructing solid waste treatments, to name a few. A similar strategy is being implemented in Bangladesh, called the Bangladesh Delta Plan 2100 which “ensures long term water and food security, economic growth and environmental sustainability while effectively reducing vulnerability to natural disasters and building resilience to climate change and other delta challenges through robust, adaptive and integrated strategies, and equitable water governance”.
Just off the coast of The Hague in The Netherlands, an artificial peninsula of 21,5 million cubic meters of sand was built to “to reinforce the coastline in the long term and to create an attractive area for leisure and nature”. The experiment, titled Zandmotor (Sand Motor), works with water, instead of against it, by depositing a large amount of sand in one go to prevent recurrent disturbance of the seabed or potential flooding repercussions. Once the peninsula is added, the sand is then redistributed along the coast and into the dunes through ocean currents, wind, and waves. Looking at cities across the Atlantic, Boston is one of the United States’ highly threatened areas, which led to the creation of “Emerald Tutu” in the Massachusetts Bay area. The project consists of an interconnected system of floating wetland and pathways that embrace the shoreline in half-ring formations. The wetlands will be used to further promote the biodiversity of the area, and the outskirts will feature a series of walkways used by the community.
In the case of Al-Arish City in Egypt, which has the potential to become a tourist and local attraction and generate income locally and regionally, the area where investments are heavily concentrated is dominated by poor planning and mismanagement. Based on these factors, a case study was published last year to highlight the sustainability approaches and practical actions needed to efficiently enhance the sustainable growth of Al-Arish city. Among the principles and policies mentioned are adopt zoning policies and building codes that support mixed-use development, matching, building scale to street, encouraging green infrastructure approaches at the site to increase resilience to natural hazards and better manage stormwater runoff, expanding and managing physical access to the water, and promoting infill development by preserving, upgrading, and reusing existing properties, to name a few.