C22-Coastal conservation measures incorporating NbS

We propose coastal conservation measures incorporating NbS to counter the effects of high waves and storm surges caused by climate change.
To date, concrete coastal embankments and boulder-based seawalls have been constructed around important infrastructure facilities such as airports and important roads in Majuro. Meanwhile, vertical concrete seawalls have been installed in some densely populated residential areas. Other, less populated areas have simple seawalls made of irregular stones or concrete rubble, or none at all.

In particular, the entire surface of the concrete upright seawall does not show the sandy beach or sediment that should be there, and it is presumed that the waves reflected by the seawall are pushing the sediment produced by the coral reef back offshore. Also, high-quality rocks and aggregate for construction cannot be obtained from atolls, so in the past, soil dredged from the nearby seabed, coral rock obtained by excavating the reef flat, and rocks obtained from other islands or continents have often been transported and used for coastal protection facilities.

Figure: Image of the seawall in eastern Majuro

Focusing on these issues, we have examined and proposed sustainable coastal conservation measures focusing on NbS for small islands, such as atolls. Currently, in areas where concrete upright seawalls exist, we are considering the following structural improvements: