Monitoring long-term land use, land cover change, and desertification in the Ternata oasis, Middle Draa Valley, Morocco

Landsat time-series with 10-year intervals from 1991 to 2021 were used to extract information on land use and land cover (LULC) changes in the Ternata oasis over the past thirty years by using maximum likelihood classification (MLC) and the normalized difference vegetation index (NDVI). MLC maps were classified in five LULC classes: cultivated land, desertified land, barren land, built-up area, and water bodies. While the NDVI maps were classified in two classes: cultivated and uncultivated land. The classes identified in the MLC maps have an overall accuracy higher than 90 percent. Results revealed a significant expansion of desertified lands (+168.09%) between 1991 and 2021. Cultivated lands, on the other hand, shrank by −29.6%. Furthermore, sixty additional Landsat images from 1991 to 2021 were analyzed and revealed a strong correlation between LULC changes in the oasis and the stored water in the upstream reservoir. The Ternata oasis has experienced significant desertification related to human and natural factors, particularly drought and the expansion of cultivated areas reliant on groundwater. Given the widespread land degradation, several local efforts are being implemented to mitigate the effects of desertification and conserve the Ternata oasis' natural resources.