An evolutionary model for sabkha development on the north coast of the UAE

The north coast of the United Arab Emirates (UAE) provides a typical example of coastal sabkha (supratidal flat) formation. Various stages of sabkha development can be recognized along this coast. This paper combines previous studies of sabkha environment with the results of field investigation of sabkha geomorphology, sedimentology, and stratigraphy on the north coast of UAE, to formulate a model of sabkha evolution.The model has six stages in the evolution of coastal sabkhas following the early Holocene sea-level rise. These are: Stage 1: sea-level rise results in the formation of an embayment. Stage 2: involves subsequent spit development and progradation across the bay as a result of sediment availability. Stage 3: coincident with spit evolution is the development of a khor (tidal inlet) with or without mangrove. Channel depth of Khors varies from 4 to 6 m. Stage 4: sediment accumulates in the khor reducing the khor depth, turning it into a lagoon. There are three sub-stages of the lagoon stage. (a) With lagoon depths of 1–2 m, (b) with lagoon depths 0.5 m or less, (c) when the lagoon floor is exposed at low tide. Stage 5: is sabkha formation; development occurs in two sub-stages. In the first the sabkha is immature and flooded during rain storms and spring tides (0.1 m above present sea-level). Later the sabkha is only flooded after rainstorms, when it reaches an elevation of about 1 m or more above present sea-level. Stage 6: in sabkha development is the coastal plain, which results when large sabkhas are linked together.