New mangrove ecosystem data along the UAE coast using remote sensing

Abstract

Characteristics of mangrove communities along the Gulf Coast of the UAE were explored using high-resolution satellite data Terra ASTER imageries in the common visible and near infra-red bands. Mangrove stands in three geographically distinctive sites, Khor Kalba, Khor Umm Al-Quwain and Al Dabbiya, were studied through spatial data and ground verification surveys. Mangroves in the UAE appear in patchy and scattered patterns, occupying about 40 km2 of the coastal zone, half of which are located in Abu Dhabi in sheltered lagoons. The remaining areas are linear communities fringing tidal waterways distributed along intertidal zones. Their distribution is limited however, by aridity and site topography. Despite similarities in substrate conditions, differences in climatic and vegetation characteristics between the three sites indicate that growth conditions seem to be more favourable at Khor Kalba with the higher winter temperatures and higher annual rainfalls. Nine main units were recognized on the colour composite image of the Terra ASTER space data; dense vegetation, scattered vegetation, algal deposits, dry sand, sabkhas, settlements, recent deposits and turbid water, shallow water and deep water. Radiance did not allow for the separation of mangrove areas from inland vegetation through the supervised classification. Confusion was also encountered between different soil classes (e.g. wet soils) and settlements or roads. It is concluded, therefore, that satellite data such as SPOT and Terra ASTER can be effectively analyzed through visual interpretations supported by local digital enhancement.