Remotely Sensed Data and GIS for Long-Term Monitoring of the Ghout Oases Degradation in the Region of Oued Souf (Northeastern Algerian Sahara)

For 12 centuries, Ghout oases in the region of Oued Souf constituted an efficient and sustainable agro-system, based on optimal adaptation to the specific local environment and limited socioeconomic needs. This study aims to spatiotemporally assess and monitor the Ghout oases dynamics in 18 municipalities in the El Oued governorate, using medium-resolution imagery of Landsat and GIS from 1987 to 2018, based on spectral indices and change detection method. The obtained results confirm the official statistics and highlight the considerable decrease in the Ghout-occupied areas from 4,462 ha (1987) to 1,033 ha (2018), especially in the northern areas, as well as increasing of the built-up superficies and extension of new irrigated perimeters throughout the entire region. The recent mutation from a traditional Oasian system based on durability and self-sufficiency into an evolved system controlled by a free economy mechanism engendered the imbalance of Oasian ecosystem functioning, which manifests in groundwater level fluctuation leading, principally, to the disappearance of the Ghout oases. For sustainable and effective Saharan agro-development, it is necessary to adopt appropriate economic strategies based on the rational and controlled exploitation of the soil and water resources.