Environmental effects of the causeway on water and salinity balance in Lake Urmia

The present investigation aims to explore the hydrodynamic and salinity distribution of the lake, following the construction of the causeway by using MIKE 3 Flow Model FM.11Flexible Mesh. The results indicate that the construction of the causeway changed the flow pattern and salinity compared to the condition prior to its construction. The salt–water balance between the two sides of the lake was not observed with the existing opening. Adding a new breach on the causeway (two breaches) revealed that, on average, the exchange flow from south to north and north to south has increased to 185 and 176 percent, respectively. The amount of the exchange of salt from south to north and north to south has also incremented to 181 and 174 percent, respectively, compared to the existing condition (one breach). The causeway with double opening paths is offered as a solution to improve the lake conditions. Moreover, results revealed that the vertical eddy viscosity is a key parameter in forming the density-stratified flow, salinity distribution, and flow circulation. [Display omitted] •The vertical eddy viscosity was the dominant factor in the formation of the density-stratified flow.•The flow and salinity patterns changed dramatically after causeway construction.•In scenario B the salt exchange decreased by 80.3% compared to scenario A.•Causeway with two breaches changed the salinity distribution in the lake.•Higher flow velocity in the breach hinder the density flow near the bed.