A temporal series of remote sensing data was acquired for the study area. It was composed of aerial photographs from mid-1970s, mid-1980s, 1999, 2000, 2005, and 2006. For conducting the change detection study, aerial photographs from 1999 and 2005 were used; this is because changes were visible on available aerial photographs only from the 1990s. No major activities were noticed from the mid-1980s aerial photographs. The software used includes ESRI ARCGIS9 software for vector processing, and ERDAS Imagine 8.4 for image processing. The selection of data, used in this study was largely governed by availability and accessibility of archived data especially at the MSD archives; the selection of hardware, and software was governed by the UAEU geology department's facilities. METHODOLOGY The methodology applied to the change detection analysis in this study is based on integrating GIS with remote sensing method, including the advantage of using GIS ability to incorporate different source data into change detection applications. Available high resolution aerial photographs of 1999 and 2005 were used, and a post-classification comparison method is implemented. Visual analysis method was used for image interpretation and simultaneously an on-screen digitizing of changed areas was performed. Texture, shape, size and patterns of the images were used for identification of LULC change through visual interpretation. A unified land cover classification scheme was established for classification of images. Eleven land cover classes were identified in the image interpretation process (Table 1). The classified images were then used to derive class area statistics and class patterns over the past 6 years. The output layers are brought into a GIS database.  Fig. 1 Location of the study area The methodology applied to the GIS database building follows the following general steps:
Production of a set of imagery spanning the period from the mid-1970s to the very new 2006 aerial photo. Imageries are geometrically corrected, co-registered, resampled to a pixel resolution of 2 meters and projected to the UTM projection zone 40N. Eleven land cover classes were produced and converted to vector format for the 1999 and 2005. Two land cover maps were produced for 1999 and 2005. Eleven land cover classes were mapped and categorized into four groups, these include:
DISCUSSION  Fig. 2 Green vegetated areas  Fig. 3 Building construction Change Detection Analysis Urbanization: changes in roads, roundabouts, and building (1999 - 2005) Table 2 shows that there has been an increase of 23.6%, 300% and 220% in roads length, number of roundabouts and buildings areas respectively between 1999 and 2005. This high increase of the level of urbanization in the island required large amounts of investment from the managing organization known as the Emirates Heritage Club, to satisfy the increased demand to build new touristic, scientific and sports facilities; e.g. horse riding halls, Olympic shooting range, Olympic swimming pools, laboratories, green houses, offices, dormitories, and the establishment of a modern road network. These facilities are used to host increasing numbers of students from all around the country as well as researchers and to emphasize ecotourism. This is attributed to the high-level political will of H.H Sheikh Sultan Bin Zayed, Chairman of the Emirates Heritage Club to transform the island from a desertified area into a well-developed reserve for protecting wild life and ecosystems and for developing ecotourism and preserving local heritage. Forestation, agricultural activities and environmental development: changes in vegetation cover extent (1999 - 2005) Total vegetation cover extent has increased from 3.742 km2 in 1999 to 5.101 km2 in 2005, an increase of 36.3% between 1999 and 2005. The density of the vegetation has also increased giving increase to the overall biomass production on the island. This biomass production can be quantified using vegetation indices calculated from satellite imagery and will eventually, be one of the objectives of future studies using satellite imagery. Furthermore, this increase in vegetation extent is mostly attributed to the increase in mangrove planted areas; indeed mangrove planted area has increased from 2.256 km2 in 1999 to 3.568 km2 in 2005, an increase of 58.2% in about six years. This gain in the mangrove -occupied areas has occurred on previously barren land which has been reclaimed and irrigated using sea water hence indicating the success of procedures applied to combat desertification, enhance biodiversity and sustain the environment on island. Mangrove is highly adapted to the conditions of the island and is known for its high salt-tolerance, as a soil stabilizer, an ideal marine and bird habitat, and can sustain bees' elevation giving uniqueness to mangrove honey production. This success in the extent of vegetated areas especially mangrove plantations, gives evidences that the UAE is wisely investing in the domain of scientific research oriented at producing species that are adapted to its climatic conditions and hence increasing green areas and combating desertification locally and in the region. Desertification and land disturbance: changes in barren land extent and footpath lengths (1999 - 2005) Barren land extent was studied as an indicator of desertification and abundance of green vegetation throughout the island, while tracks and footpaths lengths are used as an indicator of land disturbance and hence another indicator of desertification. There has been a decrease of 15 % in barren land areas between the two dates; while tracks and footpaths lengths have decreased by 32% between 1999 and 2005. This is another indicator of the decrease in desertification levels and the development of the ecosystems on the island during study period. The loss in the bare and disturbed areas is due primarily to new vegetated areas (85%), urbanization (11%), and water bodies and water channels (4%). Conservation and land reclamation: changes in water bodies and water channels (1999 - 2005) The spreading of water bodies and water channels is clear evidence of conservation and land reclamation. Table 2 shows that there has been an increase of 13.7% in the channel networks between the two data sets while water surfaces appear on the 2005 imagery only, with a large artificial salt water lagoon of 15,000 m2 (figure 4). |