摘要
A set of five satellite images from the Landsat satellite, Moderate Resolution Imaging Spectroradiometer (MODIS) and the Shuttle Radar Topography Mission (SRTM) sensors has been operated to analyze land cover and topography of the Hail region, Saudi Arabia. Image processing techniques included unsupervised classification for clustering four land cover units in the MODIS image, namely: plains, sand dunes, mountains, and cultivated lands. The SRTM image was classified to produce a thematic topographic map with 100 m elevation interval. The normalized difference vegetation index (NDVI) was applied in the Landsat images as a proxy to the change of agricultural land in Hail between 1972 and 2000. Results showed that Hail region occurs at a high plateau. Minimum elevation occurs at its northeastern corner and peaks occur at the southwestern side. The surface area of Hail is estimated at 115,690 km2. The majority of Hail area is represented by plains and sand dunes. Cultivated lands increased from 9500 ha in 1972 to 139,000 ha in 2010.
A set of five satellite images from the Landsat satellite, Moderate Resolution Imaging Spectroradiometer (MODIS) and the Shuttle Radar Topography Mission (SRTM) sensors has been operated to analyze land cover and topography of the Hail region, Saudi Arabia. Image processing techniques included unsupervised classification for clustering four land cover units in the MODIS image, namely: plains, sand dunes, mountains, and cultivated lands. The SRTM image was classified to produce a thematic topographic map with 100 m elevation interval. The normalized difference vegetation index (NDVI) was applied in the Landsat images as a proxy to the change of agricultural land in Hail between 1972 and 2000. Results showed that Hail region occurs at a high plateau. Minimum elevation occurs at its northeastern corner and peaks occur at the southwestern side. The surface area of Hail is estimated at 115,690 km2. The majority of Hail area is represented by plains and sand dunes. Cultivated lands increased from 9500 ha in 1972 to 139,000 ha in 2010.
