E3 Journal of Environmental Research and Management

E3 Journal of Environmental Research and Management Vol. 4 (11) pp. 0359-0367, December 2013; © E3 Journals; ISSN 2141-7466

Impacts of shoreline morphological change and sea level rise on mangroves: the case of the keta coastal zone

Abstract

Mangroves are faced with the challenge of coping with rising sea levels globally. They face the threat of being completely inundated should sea levels rise beyond levels they are unable to cope with.This is largely due to their location in wetlands that are constantly flooded by the sea at high tides. Many shorelines are facing the challenge of erosion and Anyanui in the Keta coastal zone in Ghana is no exception. Anyanui has a relatively large extent of mangrove cover, which apart from the pressure of human exploitation faces the threat of being inundated should sea levels go high. This study investigated the effect of sea level rise and shoreline recession on the mangroves at Anyanui, using geospatial data and modelling techniques. The local trend in rising sea level was analysed using data from a tide gauge station in Ghana. The End point rate of change method of estimating shoreline rate of change in Digital Shoreline Analysis System (DSAS), an extension in GIS was used for the shoreline change analysis, while the mangrove cover was estimated using ENVI. The results indicate that Keta coastal zone is eroding at a rate of about 2.32m/yr and the sea level is rising at a historic rate of about 3mm/yr. The study revealed that increasing sea level rise will enable the shoreline to migrate about 8 km inland in the next 100 years, which could pose a severe threat to the mangrove forest. It also emerged that there is a significant increase in mangrove cover between 1986 and 2002. Effective measures should be adopted to manage the expanding mangrove forest.

Keywords: Sea level Rise, Shoreline Change, Mangroves, Climate change, Keta, coastal erosion