3.2.2 The living coast – The Soft Approach
Urbanites often forget that life on land and sea are closely connected. For instance, estuaries supply nutrients to coastal areas, and the coastal ecosystems protect inner land from flooding via wave attenuation and help mitigate coastal erosion (Quintana et al., 2021). These coastal ecosystems are seen as alternatives to the engineered hard approach and are referred to as “nature-based solutions” (NbS) or the “soft approach.” Examples include salt marshes, beach meadows, swamps, coastal wetlands, dunes, rocks and reef-building species like seaweeds, oysters and mussel beds (see Figure 85 for an example of integrating this approach). A softer "division" between land and ocean is a key focus in these efforts. Additionally, these coastal ecosystems’ roots, leaves, fronds and shells form characteristic patch-like structures called seascapes (Boström et al., 2011) that provide a range of critical ecological and socio-economic services (otherwise known as ecosystem services as mentioned in section 1.5.2). Well-designed nature-based protection measures are gaining traction in research and practice because they can be more cost-effective in tackling climate change than hard strategies and offer other benefits. Unlike the engineered approach, ongoing and active management of such projects is unnecessary after a certain period (Pilkey and Young, 2011). A state-of-the-art project integrating marine life forms as part of the reef-building process as a form of coastal protection is called “Oyster-tecture”[167] in New York City Harbour by SCAPE Studio (see Figure 85). It seeks to revive the former oyster reefs that used to dominate the coastline to revive oysters through public educational initiatives[168] (Billion Oyster Project, 2019a).
Figure 85. Visualisation by SCAPE Studio of a project called “Oyster-tecture”, developed for the Museum of Modern Art exhibit “Rising Currents” (2009) by SCAPE in collaboration with Bart Chezar, Hydroqual Engineering, MTWTF, the New York Harbour School, NY/NJ Baykeeper, Paul Mankiewicz and Phil Simmons (Bergdoll et al., 2011). The project is a proposal for reviving the former oyster beds in New York, USA, as part of its coastal adaptation strategy. In combination with mussels and eelgrass, oyster reefs are used to build reefs for wave attenuation and harbour water filtration (Orff, 2016).
(Extracted from Kumu S-O-T-A map – Osytertecture, NYC node).
While nature-based solutions provide various benefits, it is important to be wary of greenwashing soft approaches that over-promise their coastal protection capacities, thereby perpetuating the false sense of security discussed above(Pilkey and Young, 2011). For a while, soft approaches provide certain levels of protection from storm surges; they require large-scale intervention (ranging between several hundred meters to several square kilometres depending on the local context[169]) to make meaningful impacts (Orff, 2016). Furthermore, it is complex and difficult to calculate the relationship between storm surges and nature-based solutions (NbS). Therefore, it is essential to predict the ability of NbS to reduce storm surges with computer modelling and 1:1 in-situ testing (taking into consideration various factors such as hydrology, geophysical conditions, wind, salinity etc.). Recent computer modelling and simulation advancements have reduced uncertainties and shown the different levels of coastal protection NbS can offer. For example, computer programs have simulated the dynamics of wave attenuation properties of salt marshes or kelp forests (see section 1.5.2 for more information). This area of research, however, still requires more investigation.
Furthermore, it is important to note that NbS does not protect cities from sea level rise (but can attenuate waves from storm surge events), and they should, therefore, not be promoted as capable of doing so (Pilkey and Young, 2011). There are challenges in establishing soft approaches in environments that suffer from water pollution. For instance, urban areas that suffer from severe water pollution (i.e. eutrophication), poor water clarity due to floating particles from agricultural runoffs, lack of sediment flow due to locks and gates at the mouth of the river, dead marine zones due to stone and gravel extraction, and increasing cloudbursts affecting the salinity levels, to name a few. While hard-engineered approaches tend to ignore these interconnected ecological systems of larger external pressures, working with soft approaches makes us face them (otherwise, they will not work) (ibid.). Therefore, careful analysis and interdisciplinary collaboration are required to successfully implement soft approaches to understand the various factors inhibiting coastal ecosystem restoration efforts (Organo Quintana, 2020). Furthermore, while NbS have the added benefit of providing more than coastal protection by sequestering carbon as part of the climate mitigation strategy, the sequestration of greenhouse gases takes place over long timescales relative to the emission rate of anthropogenic greenhouse gases. Therefore, the effectiveness of these solutions is sustained only for as long as they remain permanent carbon sinks which is difficult to achieve (see section 1.5.2 for the potential for kelp being a more permanent carbon sink) (Beardmore, 2021).
Ultimately, what I wish to propose with regard to the implementation of NbS is that there are limitations in relying heavily on one system (i.e. hard approach), making it vulnerable to responding to the complexity of numerous issues that may arise from climate change. Therefore, I will be suggesting throughout the remainder of this chapter that a diverse set of approaches (some hard, some soft) will become critical to ensure that the most flexible and holistic strategies can be implemented at the coast (Hill, 2015). It is critical that coastal cities move past short-term quick-fix strategies to prepare for future unpredictable scenarios (Hill, 2015; Pilkey and Young, 2011).
[167] SCAPE Studio’s design-research for the Oyster-tecture project has evolved to inform multiple ongoing projects, including the large-scale ecological infrastructure proposal called “Living Breakwaters” which is currently being constructed to be completed 2024-2025 (Billion Oyster Project, 2022c; SCAPE Studio, 2022).
[168] Oystertecture is part of the “Billion Oyster Project”, a non-profit organisation to restore the former oyster reefs of New York’s shorelines by 2035. More than 30 million oysters had been restored, with 7 acres (28,000 m2) of reef area restored, filtering billions of litres of water (i.e. nitrogen). New York harbour water quality is the cleanest in 100 years. Approximately 2,000,000 oyster shells have been recycled. More than 6,000 high school and middle school students have taken part in the project. (Billion Oyster Project, 2022b).
[169] This is based on findings from a coastal engineer working on nature-based solutions/soft approaches in NYC (Orff, 2016), an interview with a marine biologist working with nutrient uptake of kelp in Denmark (Boderskov, 2021) and the wave attenuating properties of natural kelp forests off the coast of Norway (Mork, 1996).