Coastal processes and sedimentary facies in the Zohreh River Delta (Northern Persian Gulf)

Abstract

The Zohreh River Delta is one of the largest deltaic plains along the northern coast of the Persian Gulf. This delta is located near an international navigation corridor, which is affected by long-term delta progradation. Therefore, the research objectives of this study were to determine the coastal sedimentary processes of the Zohreh River Delta and to detect the evolutionary trend of the deltaic plain at the northern Persian Gulf. The research method was formulated to achieve objectives herein, including field measurements, numerical modeling, remote sensing and laboratory analyses. The results showed that flash floods and turbidity currents transport sediment to the deltaic area, and tidal currents play an important role in sediment redistribution and in the high diversity of sedimentary facies. Flood plains, tidal flats, crevasse splays, nebka, and sabkha are the most important sedimentary facies in the study area. Gypsum and salt crystal are frequently grown in supratidal and intertidal zones because of a dominantly arid climate. The river and tidal currents are responsible for an annual sediment transport of 321,310m3, while the sediment transport by littoral drift is calculated to be 81,000m3 annually. MIKE-21 (a coastal modeling software) revealed that 80% of the sediment is transferred into the subtidal zone and the remaining 20% is deposited at the river mouth. Applications of GIS tools showed that the mean annual sedimentation rate at the river mouth and the long-term shoaling rate have been 0.07m and 2.45m, respectively. The rate of long-term progradation of the delta implies an increase of sediment supply from the catchment area due to land use changes and river bank erosion. A key part of this research is presenting the implications of the permanent shoaling trend which is prograding toward the international shipping corridor at the north of the Persian Gulf.