22. Use of Remote Sensing and GIS for Land Degradation Assessment of Qarun Lake Coastal Area, El-Fayoum, Egypt

El-Fayoum Oasis is a depression or basin in the western desert that is adjacent to the Nile, Egypt. It locates about 130 km southwest of Cairo. Qarun Lake is the only natural contemporary lake in Middle Egypt. The lake is saline with an elevation about 44 m below sea level. It receives drainage water from El-Fayoum Depression but has no surface outflow. Wadi El-Rayan Lakes have been receiving drainage water since April 1973. El-Fayoum is now an intensively agricultural region supported by abundant freshwater from the Nile River via the Bahr Yusef Canal. The main objective of this study is to use Landsat multitemporal images to detect and monitor the changes of Qarun Lake coastal area. To fulfill this objective, Landsat data (path 177/row 40) are as follows: Landsat MSS 1973, Landsat TM 1988, Landsat ETM + 2003 and Landsat-8 2015, and topographic maps (1992) scale 1:50,000 were used. Geometric correction, Image enhancement, and visual interpretation were carried out on the images and maps. Digital elevation model (DEM) and the vector contour lines of the study area were used. ArcGIS 9.2 software had been applied for mapping environmental changes around Qarun Lake in the investigated area. ENVI 4.2 software was also used to produce the physiographic map of the study area. The obtained results from the digitized topographic map (1942) showed that the surface area of Qarun Lake was about 21 km². From that time, the surface area of the Lake was more or less stable and it was in a balance with land use in El-Fayoum Depression base on the interpretation of the remotely sensed data. In 1973 the surface area of Qarun Lake reached the maximum (240 km²) due to receiving the excessive drainage water from El-Fayoum Depression. The surface area of Qarun Lake decreased to about 230 km² by 1988. Since that time until 2013 the surface area of the lake was almost stable.