Arid land salinization detected by remotely-sensed landcover changes: A case study in the Siwa region, NW Egypt

摘要

Siwa region, located in the north Western Desert of Egypt, has been recently subjected to severe soil salinity problems. Monitoring and analysis of the recent landcover dynamics through the integration of remote sensing and GIS could provide base information for documenting salinity change trends and for anticipating further degradation where the absence of long-term salinity records is an obstacle. Three Landsat TM/ETM+ satellite images taken over a span of 16 years (1987-2003) coupled with a 30-m DEM and field observations served as the basic sources of data. Standard image enhancements, classifications, and change detection techniques were applied to determine changes between the available images. Changes were analysed in conjunction with the land surface characteristics, such as slope, radiometric thermal temperature, vegetation indices, and tasselled cap transformations. Such analyses enabled the characterization of alterations in vegetation cover and provided evidence for locating possible future changes due to soil salinity. The results confirmed an acceleration in the rate of soil salinization and vegetation death after the year 2000. Further, this was found to be related to the relative climate warming and the improper drainage systems set up after the year 2000 in addition to the absence of an effective water resource management plan. Recommendations and measures that may prevent or ameliorate the exacerbation of these problems are proposed.