Monitoring and Assessment of Environmental Changes in Siwa Oasis, Egypt

Abstract

Anthropogenic activities were and will remain one of the most influential factors driving environmental changes. Human induced changes can reflect political, social, economic and ecological conditions prevailing an area in general or over a certain period of time. Three remotely sensed satellite images with a time lapse of fourteen years period of time (2003 – 2017) were obtained and investigated to detect changes that took place during that period and the ecological implications of these transformations. Satellite images were atmospherically and geometrically corrected. Normalized difference vegetation index (NDVI) was calculated for all images. Unsupervised and supervised classifications were applied to identify different environments. Change detection techniques were used to detect alterations in different surfaces. Results were combined and compared to previous studies of the same study area. Six classes were recognized and the overall changes showed that vegetation, water bodies and urban are increasing while salt marshes, sabkhas and barren soils are decreasing. However, changes are unequally distributed all over the whole oasis.  Anthropogenic activities are the major trigger of all detected changes where the irrational use of water, lack of drainage system is intensively affecting all environments of Siwa Oasis. The present study expects the further expansion of the current water bodies which may escalate salinity problem with accumulating more salts in the soils of Siwa Oasis. Vegetation cover is also increasing and according to the results it is going to increase more in parallel with water bodies. Combination of our results and previous results during the period from 1987 to 2003 have confirmed our results and showed a clearer trends for the changing course in the major environments. Water management and raise of awareness should solve the problem of water bodies expansion and restrain the intensification of many of Siwa Oasis ecological problems.