Quantitative estimation of land cover structure in an arid region across the Israel-Egypt border using remote sensing data

摘要

The clearly visible border between the Israeli Negev and the Egyptian Sinai in remote sensing imagery is a very interesting phenomenon that has long been studied. The widely accepted explanation to this observation is a viewpoint of anthropogenic impacts on the arid environmental ecosystem across the border. In order to examine the validity of this viewpoint, three methods were employed in this study to determine the quantitative structure of main land cover patterns (biogenic crust, bare sand, vegetation and playa) in the arid region: field observation, measurement on aerial photograph, and analysis of vegetation cover changes on Landsat Thematic Mapper (TM) and SPOT images. Field observation on the Israeli side indicated that vegetation covers ～16% of the ground, biogenic crust ～69%, sand ～12% and playa 3%. Evidence from aerial photograph supported a sharp contrast of vegetation cover across the border, with ～17% on the Israeli side and ～6% on the Egyptian side. Analysis of the available TM/SPOT images indicated a high vibration of seasonal vegetation changes in the region. The Israeli side had a vegetation cover rate ranging from above 18% in the growing season and below 5% in the dry months. The rate on the Egyptian side changes from less than 2% in the dry season to ～5% in the growing season. Therefore, it is reasonable to estimate surface composition structure of the region as follows: vegetation, biogenic crust, bare sand and playa account for 5-18%, 71-84%, 7.5% and 3.5%, respectively, on the Israeli side, and 2-5%, 12.5%, 79-82% and 3.5% on the Egyptian side, depending on the season. This estimate of land cover structure has been successfully used to model land surface temperature differences across the border, in order to understand arid ecosystem evolution in the region.