Salt Encrusted Desert Flats (Sabkha): Problems, Challenges and Potential Solutions

The evaporative and sedimentary environment that has prevailed over the southern shores of the Arabian Gulf region (eastern Saudi Arabia, Qatar, and United Arab Emirates) has produced salt-encrusted flat areas known in Arabic as "sabkha". Building activities on sabkha areas have posed problems and challenges to the construction industry, triggered primarily by the excessive salts present in both the sediments and their shallow ground waters. In general, sabkha sediments are cemented and uncemented layers of sand /silt material, interbedded with pockets of clay and mud, where calcium carbonate and more recent digenetic minerals (gypsum, anhydrite) serve as the principal cementing agent. The geotechnical aspects of sabkha are addressed with particular reference to building foundations. Simplified soil profiles from selected sabkha sites with Standard Penetration Test Results are shown. The effectiveness of some soil densification methods, as a means of improving engineering properties of sabkha sediments, is touched upon. The paper concludes by offering guidelines for proper field investigation in sabkha terrain, with a geochemical component as an essential part of the geotechnical investigation.