Kosrae's Coast
Reducing coastal hazard risks on Kosrae
reducing risks
The need for seawalls
Seawalls, or other forms of constructed coastal defences are typically seen as the "solution" to coastal erosion and flooding problems.
In the vast majority of cases seawalls, in the long term, cause more problems that they solve.
Unless great care is taken, building seawalls often causes further erosion on adjacent sections of coast. Such effects can be seen at many locations on Kosrae, e.g. the problems at Sandy Beach Hotel a few years back.
Furthermore where such structures become permanent features there will be longer-term impacts that will affect the natural ability of Kosrae's coastline to build up and respond to the long-term effects of sea-level rise. Such aspects are rarely considered but are important if Pacific Islands such as Kosrae are to successfully adapt to climate change effects.
In many situations seawalls essentially ‘lock in’ future generations to a permanent reliance on coastal defences and the associated costs of maintaining and upgrading these defences.
Most constructed coastal defences on Kosrae's coastline protecting residential property will have a limited lifespan, at best probably around 10 to 20 years. They are generally not constructed to a standard to effectively withstand the more significant storm events that can occur.
In many cases maintaining defences to an adequate standard is not affordable in the long run. Ultimately property and other assets located on land behind such defences will need to be relocated.
The committment Kosrae now has to maintain and upgrade existing seawalls around the island is considerable. There is a need focus on prioritising what is protected and ensure that existing seawalls are maintained to an adequate standard before any further coastal defences are considered.
It is likely that this proritisation will need to focus on protecting infrastructure to enable more time to plan for, and to relocate infrastructure that is at risk.
Further details of seawall needs are descriped in the strategy document that can be downloaded from the link above.
In this section:
- The need for seawalls
Downloads:
(C) Doug Ramsay & KIRMA, 2008
Seawalls and other forms of coast protection are, in most cases, not as permanent as communities apparently "protected" by them assume.
This is a particular issue on Kosrae and other Pacific Islands where the range of construction options and materials available are typically limited.
In many situations the construction of such defences and the perception of the protection that such structures provide have over time significantly increased the level of risk facing communities on Kosrae.
Protection is not permanent......
Locking in future generations......
Causing further erosion problems....
A considerable existing committment....
No coastal defense on Kosrae will protect the land behind it from the effects of an extreme event such as a typhoon or large storm coinciding with a high tide. Even with coastal defenses, property or infrastructure located close to the coast will still be at considerable risk from storm damage and flooding on Kosrae.
Coastal defences on much of the open coast of Kosrae will exacerbated erosion on adjacent sections. Locations where such problems will occur if seawall structures are built along a coast include:
- North Tafunsak coast between Inkoeya and Yekula, and between Malsu and Finfoko.
- North Walung coast between Insiaf and Koasr.
- East Lelu coast between Finaunpes and Finpukal.
- North Malem coast from Tenwak to Yewak
- South Malem coast from Malem to Taf Te in Utwe.
Locations of existing seawalls (blue), and where new seawall construction could result in further erosion problems (red).