Editing IPCC:AR6/WGII/Chapter-15 (section)

=== 15.5.1 Hard Protection ===

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Seawalls have been a popular coastal protection measure on islands (Figure 15.7). An analysis of National Communications shows that 28% of coastal protection actions are seawalls, followed by breakwater structures and coastal protection units ( [[#Robinson--2017a|Robinson, 2017a]] ). Coastal protection infrastructure has been heavily invested, for example, in the Caribbean region ( [[#Mycoo--2014b|Mycoo, 2014b]] ) and Cuba ( [[#Mycoo--2014a|Mycoo, 2014a]] ). A similar situation applies in many Indian Ocean islands, where coastal protection strategies are manifested by hard shoreline structures, many of which are proving challenging to maintain ( [[#Naylor--2015|Naylor, 2015]] ; [[#Betzold--2017|Betzold and Mohamed, 2017]] ; Magnan and [[#Duvat--2018|Duvat, 2018]] ). In the Pacific the situation is different given that many islands have been occupied for millennia by indigenous communities with extant knowledge for coping with adversity ( [[#Granderson--2017|Granderson, 2017]] ). The latter generally favours ‘soft’ shoreline structures for coastal protection although the building of seawalls has been rapid, especially in urban islands ( [[#Umeyama--2012|Umeyama, 2012]] ; [[#Duvat--2013|Duvat, 2013]] ; [[#Magnan--2018|Magnan et al., 2018]] ; [[#Morris--2018|Morris et al., 2018]] ), and also in some rural islands (e.g., Tubuai, French Polynesia ( [[#Salmon--2019|Salmon et al., 2019]] )).

Many rural communities have uncritically emulated structures in urban contexts built and maintained with external finances. As a result, in many Pacific SIDS, seawalls have collapsed without additional funding available for repairs ( [[#Nunn--2018|Nunn and Kumar, 2018]] ; [[#Piggott-McKellar--2020|Piggott-McKellar et al., 2020]] ; [[#Nunn--2021|Nunn et al., 2021]] ). Similar cases have been recorded along the coast of Puerto Rico ( [[#Jackson--2012|Jackson et al., 2012]] ) while on Indian Ocean islands (e.g., Seychelles), the shorelines are littered with broken seawalls and groynes ( [[#Duvat--2009|Duvat, 2009]] ). In Samoa, seawalls close to Apia need constant investments to remain viable.

On small islands, another widespread issue with seawalls and other hard shoreline structures is that they invariably shift problems of shoreline erosion and lowland inundation elsewhere ( [[#Donner--2014|Donner and Webber, 2014]] ). Even surrounding entire islands with such structures, as has happened on Male’ (Maldives), is not a long-term solution because of incidences of localised seawall collapse that can spread quickly if not addressed immediately ( [[#Naylor--2015|Naylor, 2015]] ). Hard structures for coastal protection will become increasingly ineffective in the future, demonstrating the need for adaptation along most island coasts to become more transformative than has been the case over the past few decades. In the Bahamas, it has been suggested that coastal protection structures and strategies are implemented through ‘a rather piecemeal approach of single projects and small patches, partially resulting in maladaptation by further increasing processes of erosion’ ( [[#Petzold--2018|Petzold et al., 2018]] , p. 95). In the village of Lalomalava, Samoa, national adaptation funding was spent on erecting a seawall to protect the village, but the wall was not long enough to protect the whole village, leading some families and properties to face increasing impacts from large waves ( [[#Crichton--2018|Crichton and Esteban, 2018]] ).

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