Wave–flow coupling effects on spatiotemporal variations of flow and salinity in a large hypersaline marine system: Lake Urmia, Iran

On many occasions, the effects of wind-induced waves and currents on flow and salinity fields in water bodies are evaluated separately. Some coupling mechanisms of the two phenomena, however, can have a significant impact on the flow and salinity conditions, in particular in sensitive aquatic ecosystems. This article attempts to quantify the wave contributions to the flow and salinity regimes in Lake Urmia, Iran. The salinity conditions in the lake have become an environmentally important subject, partly because this shallow hypersaline aquatic ecosystem is considered to be one of the largest natural habitats of a unique multicellular organism, Artemia urmiana. This brine shrimp is the major food source for many of the protected and rare shorebirds that visit the lake and can grow and survive in only certain ranges of salinity. The lake has also experienced considerable man-made changes during the past three decades. Previous studies that have modeled the flow and salinity regimes in the lake have overlooked the wave-coupling effects, and some have concluded that major remedial actions are necessary to restore the lake ecosystem. The wave-coupling effects were found to have significant impacts on the spatiotemporal variations of flow and salinity in the lake. Wave actions were intensifying vertical stratification, considerably influencing the flow and salinity regimes. It was found that improvements in the lake salinity conditions provided by the wave actions were comparable to potential improvements that expensive mitigation scenarios may offer. The relative magnitude of the wave coupling was found to be the highest in shallow/large water bodies, and it increased as the wave height and the initial salinity increased, suggesting that these wave-coupling effects are substantial, especially in large, shallow, hypersaline lakes.