Risk reduction, adaptation or avoidance
SLR, on a global scale, is inevitable. So, strategies to manage the risks of SLR and adapt to it are what we need now. Different nations are planning in diverse ways and have developed numerous solutions to deal with the issue. We can divide the strategies into 3 categories – risk reduction, adaptation to risks, and risk avoidance.
Table 1: Classification of the response options to SLR
I. RISK REDUCTION (BAU)MEASURES – TECH FIX
A. In this direction, a major response measure includes opting for flood control measures, such as the minimization of land subsidence which must be opted in regions that are below sea level or are facing sinking or subsidence due to excessive extraction of groundwater resources.
Vast areas of the Netherlands that lie below the mean sea level and are highly flood-prone have successfully adopted this method.
In Tokyo also, the subsidence of land has been minimized by reducing the pumping of groundwater.
Shanghai has resolved this problem by not only limiting pumping but also by recharging its aquifers.
B. Another measure is the hard protection technique, i.e. installation of engineered structures such as dikes, surge barriers, seawalls, flood gates etc., mainly to hold back the seawater during storm surges, high tides, and currents, triggered by SLR. Such hard protection plays a pivotal role in the adaptation of densely populated and low-elevated areas.
The public authorities in the Dutch coastal cities have reinforced 37,000 km of hard-engineered structures like seawalls and dikes, including the well-known Maeslant barrier to protect them from SLR.
Jakarta is also constructing a massive sea wall with Dutch support.
A system of flood barriers or flood gates is installed in the Thames River and are closed during a storm tide in the North Sea to protect London and keep London dry.
Seawalls and breakwaters are dotted over Puducherry’s coast too, thus providing artificial protection from SLR.
The German island of Pellworm lies a metre below sea level, and hence, is surrounded by towering dikes to keep the storm surges out.
Dikes – a hard protection against floods triggered by SLR
C. Beach nourishment or widening of the beach using outside sand and restoration of dunes can also reduce the impact of the SLR hazard. Though these techniques of soft protection are expensive to implement and can be environmentally destructive in the long run, they can be modified as per the levels of SLR and help to carry out the preservation of beaches and related tourism activities.
Since 1923, beaches resided by 475 U.S. communities have been nourished by more than 1.35 billion cubic meter of sand, at the cost of USD 10.8 billion. In fact, most of the states in the US have long-term beach management plans to fight SLR.
In 2021, Thiruvananthapuram’s Minister For Transport Antony Raju has come up with the idea of beach nourishment along Poonthura and Veli as the sandy beaches here are being highly prone to strong waves.
The Hillsboro beach of Florida has also been expanded by 38,500 cubic yards over 3 years.
Beach nourishment – a soft protection technique to reduce the impact of SLR
D. Shoreline protection can be carried out by the natural vegetation including mangroves and marshes, coral reefs, seagrass meadows that would act as buffers and thus, would not allow the high water levels (in the form of large waves or storm surges) to enter the mainland, would reduce erosion, would minimize land subsidence and create new lands by trapping sediments. All over the world, efforts are going on to restore the marshes and mangroves for the concerned protection.
Muthupet, a town in Tamil Nadu, lost a considerable portion of its mangroves to the 2004 tsunami. However, the Emergency Tsunami Reconstruction Project helped to restore 2000 hectares of mangroves in the region and this measure is surely going to account for the future SLR.
Mangroves –protection from high water levels
(Image source: Oceanographic magazine
Though the above-mentioned environmental or technological fixes are appreciable risk reduction efforts, they come with certain limitations such as high maintenance costs, lack of flexibility, risk of infrastructure failure, decrease in effectiveness (mainly in the case of soft protection techniques), etc. These imply that risk reduction may delay the societal collapse caused by SLR, but it cannot be considered a sustainable solution. In many ways these responses represent an effort to continue business as usual (BAU) of Industrial Civilization with minor corrections- nowhere close to any systemic response to the risk of societal collapse.
II. RISK ADAPTATION / WEAK SUSTAINABILITY (WS) MEASURES
A. The modification of design standards and building codes of buildings or infrastructures vulnerable to the risks of SLR can aid in adapting to the issue. Increasing the building elevations or floor levels, bringing changes in their foundation designs, and floodproofing them can be done in this aspect. However, this solution may not be effective in the long run. It is applicable only for buildings or infrastructures that will be constructed in the future.
Vancouver in Canada is a significant example of a city that has used building codes and design standards to address the SLR issue. In 2014, it made the minimum flood construction levels to be a metre higher to keep up with the SLR projections up to 2100.
Helsinki in Finland had also decided to modify its design standards by increasing its floor levels by 1-3 metres above mean sea level in the late 1980s to account for the SLR.
Kerala in India is witnessing the construction of flood-resistant houses on pillars to make floodwater flow from below.
Christchurch in New Zealand, in its updated city plan, includes provisions such as raised floor levels and setbacks from waterways to make the vulnerable areas adapt to flooding.
Increasing building elevations – a solution for SLR
(Image source: floodlist.com)
B. Emergency management can also be done by measures such as the implementation of early warning systems for floods. Undoubtedly, such systems can reduce the losses of lives and properties caused by coastal inundation, but they are not very cost-effective solutions and at times they are unable to predict storm surges accurately.
The Flood Early Warning System (FEWS) was launched in India by the Energy and Resources Institute (TERI) and National Disaster Management Authority (NDMA) in 2020 for Guwahati to alert local authorities about flash floods.
The Central Asian Flood Early Warning System (CAFEWS) is also supposed to provide a shared virtual platform for data exchange and flood forecasting to manage the transboundary risks posed by weather, climate, and water. These technological or environmental fixes help to mitigate the losses caused by SLR to a great extent. But the issues arise when all countries do not have equal access to such property-level technology. Moreover, they come with significant development costs and yet in some cases fail to provide certainty.
III. RISK AVOIDANCE/STRONG SUSTAINABLITY (SS) MEASURES & STRUCTURAL-COGNITIVE FIX
A. To avoid a population’s exposure to SLR, the first measure could be prevention of new development in the areas vulnerable to floods and erosion caused by SLR. This can be done through strict land-use regulations, government order of zoning, refusal of banks to grant loans for buildings to be built at a certain distance from the sea, etc.
The National Spatial Plan of Netherlands is meant to avoid unwanted land use developments along coasts from taking place. In the Netherlands, the government has decided to not provide protection for new development in high-risk areas
As per the new Coastal Regulation Zone Rules (2019) of India, there is a no-development zone of 20 m for all islands close to the mainland coast, and for all backwater islands in the mainland.
B. Preventing new development in the coastal area implies relocating or planning to retreat people, infrastructures, and assets in areas that are not vulnerable to the impacts of SLR.
Many cities have already started to plan to respond to rising sea levels in this way. For instance, in California USA, the managed retreat is already being given a thought for many communities residing in the coastal areas.
C. Awareness of the issue is also necessary so that the communities voluntarily vacate the risk-prone coastal areas. In this regard, they must be provided with access to information, tools, and guidance about SLR.
An Australian web-portal “CoastAdapt” provides tools such as inundation mapping software, information on local coastline morphology, coastal climate adaptation decision-making guidance, as well as local and international case studies.
A networking platform called the ‘Knowledge Hub on SLR’, a joint effort between JPI Oceans and JPI Climate, promotes the generation, synthesis, exchange and integration of information on SLR at local, regional and global, historic and future levels.
The California Natural Resources Agency, in 2021, launched a statewide multi-language campaign ‘The Ocean Is Moving In’ to spread awareness about the SLR’s threat to coastal and inland communities.
These Strong Sustainability (SS) measures will most likely be considered in the long run mainly when protection and accommodation are no longer affordable or cost-effective.
The 3 strategies to deal with SLR
So, which option of responding to the SLR should be opted for?
The weak sustainability options, i.e. the efforts to reduce impacts and vulnerability of SLR through environmental or technological fixes are not sustainable from many aspects. Undoubtedly, ceasing the overall exposure to the hazard involves issues like applicability for only new or future developments and compensating the old owners but is a much less risky measure in itself. Despite that planned retreat is not yet needed to be implemented widely, the planners must keep it in mind for the longer term mainly if the measures of protection and accommodation cease to be affordable or feasible. Also, if safe land is available, the development in coastal floodplains should be prevented to avoid destruction or adaptation investments in the future.
SLR represents a classic case of ‘Catch-22’ situation where the response may be as harmful as the risk exposure. Considering the fact that bulk of the global GDP and Trade depends on existing coastal infrastructure and communities, it is unlikely that intentional implementation of such measures can avoid triggering a collapse of globalized economy.
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