Maintaining and restoring native coastal vegetation in response to sea-level rise
Without stable shorelines, the integrity of infrastructure such as as soil binders and as effective filters, thus maintaining coastal
roads, airports, buildings, and residences may be threatened. berms and forests. They are part of the dynamic coastal sys-
In addition, significant amounts of salt water may infiltrate the tem, well adapted to shifting shorelines. In contrast, seawalls
groundwater and degrade drinking-water sources, wetlands, are static, immobile objects that do not conform to the advance
and agriculture. and retreat of shorelines. When shorelines shift, sea walls may
become undermined and no longer function (Figure 6C.8(a)).
Intact native vegetation is ideal for stabilizing shorelines. For Furthermore, seawalls and other similar construction activities
example, plants indigenous to tropical islands have evolved to often disrupt or displace native vegetation communities. Pre-
tolerate high temperatures and humidity, salt water, extreme serving and restoring this vegetation helps maintain shoreline
sunlight and storms. These vegetation communities function integrity in the face of rising sea level (Figure 6C.8(b)).
(a) (b)
Figure 6C.8: Shoreline integrity in the Fijian village of Yadua.
(a) Part of the degraded seawall protecting the village – storm waves penetrate into the land behind the damaged sea wall and
erode the coastal flat on which the village lies.
(b) Mangrove nursery and recent foreshore plantings.
Photos: Patrick Nunn
Relative sea-level rise has a wide range of effects on interact with the immediate effects of sea-level rise and
coastal systems, summarized in Table 6C.1. The imme- often exacerbate them. For instance coastal erosion,
diate effect is submergence and increased flooding of which on sandy coastlines occurs at tens to hundreds
coastal land, as well as saltwater intrusion into surface of times the rate of sea-level rise, will tend to degrade or
waters. Longer-term effects also occur as the coast ad- remove protective coastal features such as sand dunes
justs to the new environmental conditions, including and vegetation, thereby increasing the risk of coastal
increased erosion, ecosystem changes, and saltwater flooding (see box on maintaining and restoring coastal
intrusion into groundwater. These longer-term changes vegetation).
CHAPTER 6C ICE AND SEA-LEVEL CHANGE 165