Wetland land cover change detection using multitemporal Landsat data: a case study of the Al-Asfar wetland, Kingdom of Saudi Arabia

Abstract

The Al-Asfar wetland, locally known as Lake Al-Asfar, is the largest inland wetland in the Arabian Peninsula. It is situated to the east of the Al-Ahsa Oasis. It was formed at the expense of the Umm Hishah sabkha via the discharge of increasing quantities of drainage water to the oasis. This research was conducted to assess changes in land cover using four satellite images collected from 1990 to 2020. The study used a Landsat 5 TM image (1990), a Landsat 7 ETM+ image (2000), a Landsat 8 OLI-TIRS image (2010), and a Landsat Sentinel-2 L2A image to examine land cover in the Al-Asfar wetland. The normalized difference vegetation index (NDVI) and normalized difference water index (NDWI) were used to evaluate the tendency of ecosystem evolution. The results indicate that for the past three decades, the wetland area has increased significantly. Approximately 15.46 km 2 (24.69%) of the body of water was added during this time frame, and the vegetation areas expanded to approximately 10.74 km 2 (17.15%). The changes detected in the study area can be explained by the discharge of agricultural drainage water and semi-treated water from sewage treatment plants and the spread of reed mites ( Phragmites australis ) which covered approximately 23.81% of the area of the Al-Asfar wetland in 2020. For these reasons, the study recommends the necessity of imperative consideration for the protection of the resources of other wetlands in Saudi Arabia to ensure their sustainable use for future generations.