Egypt's Coastal Salt Flats Expanded Over 12% in 50 Years, Study Finds

Coastal salt flats known as sabkhas along Egypt's southern Red Sea coast expanded by more than 12% collectively between 1973 and 2023 according to a study published in the journal Scientific Reports. Researchers, including Nada A. Younis, Galal H. El-Habaak, Hany H. El Hadek and Wael F. Galal, analyzed satellite imagery spanning five decades to track four sabkhas — Ras Baghdadi, Marsa Abu Madd, Bir Shalatein-Marsa Himeira and the Diib alluvial fan. Sabkhas are coastal salt flats that form where seawater and land runoff meet and evaporate, leaving crusts of salt.

Individually, Ras Baghdadi grew by nearly 0.4 square kilometers (0.15 square miles), Marsa Abu Madd expanded by 4.55 square kilometers (1.76 square miles), and the Diib alluvial fan added 8.46 square kilometers (3.27 square miles) to its footprint. The Diib fan is fed by a drainage basin — the area of land whose water flows into one outlet — covering 42,000 square kilometers (16,200 square miles) that stretches from central Sudan to the Red Sea coast.

The researchers attribute the expansion to two combined forces: rising Red Sea levels pushing saltwater further into coastal aquifers, and intensifying heat and dryness in the region, with evaporation rates peaking at 28 millimeters per day in summer. They say sabkha growth is likely to accelerate as the climate continues to warm.

Sediment layers dug from pits at Marsa Abu Madd showed alternating tidal deposits from wetter phases and windblown sand from drier spells, recording past shifts as the sea advanced and retreated. At Ras Baghdadi, fault lines channel seawater and mountain runoff into a saline pond that has changed shape since 1973 and now supports microbial mats and migratory birds.

The four sabkhas remain largely undeveloped despite growing pressure to build along Egypt's Red Sea coast, giving researchers what they describe as a rare baseline for measuring environmental change without human interference.