Sea Level Activities and Changes on the Islands of the Western Indian Ocean

Abstract

During the Tropical Ocean Global Atmosphere (TOGA) 10- year programme (1985-
1994), a sea-level study network was established in the Western Indian Ocean (WIO) to monitor
sea-level variations. Most of these stations together with additional stations maintained by
countries outside the region now form part of the Global Sea Level Observing System (GLOSS).
The monthly research quality dataset for 13 island stations in the WIO between 06°N and 46°S
and between the African coast and 80°E from the Joint Archive for Sea Level, located at the
University of Hawaii, was used for the study. Using linear regression and 12-month moving
average statistical methods to analyse the data, some useful results were obtained in spite of
the short duration of the time series. It was noted that eight out of the 13 stations showed a
rising trend and four a falling trend, a tendency illustrated also by TOPEX/Poseidon satellite
data (1993-2000). This provides some evidence that there is no clear indication of any great
acceleration in sea level rise in the region. The GLOSS network should be maintained and
expanded with additional stations of regional importance to ensure a long term series of sea
level data to monitor sea level changes. This is a useful input in decision making for sustainable
development of coastal resources as well as providing a vital tool to detect tsunami signals for
early warning purposes.

Keywords: Sea level changes, Western Indian Ocean Islands, Impacts of sea level change

West Indian Ocean Journal of Marine Science Vol. 5 (2) 2006: pp. 179-194