This paper focuses on Zanzibar Island, also known as Unguja Island. There has been a main focus on the western side of the island, in particular the locations of Stone Town and Zanzibar City. These are the cities that have the most development. Other areas that were used in the study are Bwejuu along the eastern coast and a area along the south western coast of Zanzibar within the protected area. These areas were studied to show that development and deforestation were increasing in areas that were not within the main commercial areas.
Global Land Cover Facility (GLCF)[i] was used to collect Landsat and elevation data. Once on the GLCF website, Earth Science Data Interface (ESDI) was used to download images and locate Zanzibar island. A map search on ESDI was used to locate the island. Enhanced Thematic Mapper (ETM+) was used for Landsat data and Shuttle Radar Topography Mission (SRTM) was used for elevation data. The clearest and most complete image of the island was identified and downloaded.
Once the image was downloaded, it was entered into the ENVI software program where the images were modified. All of the images were subset so that only Zanzibar was clearly shown. The elevation data was enhanced allowing a clearer image of the elevation. A density slice was also applied to the image as well as a 3D model. The Landsat ETM+ image was turned into an NDVI. However, since there was a lot of cloud cover over the island and there was not a better image on GLCF, this image was not used.
To get a better image of the island (one with less cloud cover), Glovis through the United States Geological Survey (USGS)[ii] was used. Once on the Glovis website, the Zanzibar island was located. Once located, the clearest image was selected and downloaded. When the image was downloaded, it was opened with ENVI where the image was subset to focus on Zanzibar and turned into an NDVI.
The NDVI shows the vegetation of the island. In order to get a better idea of the where the vegetation was a density slice was applied to the image. The elevation images and NDVI images were than compared to other images and maps of Zanizibar that were found online. A simple Google image search was done to locate a comparative image. Unfortunately there was not an image available for comparison for the elevation data. There was a vegetation map[iii] that was found and was compared to the NDVI image. Images from Google earth were also used as a comparison.
A time series through Google earth images was also conducted to look at the increase or decrease in vegetation on Zanzibar Island. The information provided by Google earth covers the period 2001-2010. The time series started in June 2001. The images were than looked at in one-year intervals around the June or July. The June and July images provided the clearest images with the smallest amount of cloud cover. Since there was a lot of cloud cover, an area in the southern western part of Zanzibar and an area in the northern western part of Zanzibar were put under a time series through Google earth and compared to the images from Glovis and GLCF.
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