Mohammad Hassan Ranjbar - Pouya Tarh Pars Consultant Engineers, Tehran, Iran
Majid Jandaghi Alaee - Pouya Tarh Pars Consultant Engineers, Tehran, Iran
Mostafa Nazarali - ouya Tarh Pars Consultant Engineers, Tehran, Iran
Mohammad Noori - Golestan Regional Water Authority, Gorgan, Iran

Serious concerns have recently been raised about Gorgan Bay due to water quality degradation and eutrophication, which has adversely affected the ecologicalconditions of the bay and the standard of living of the people inhabiting around it. For example, poor water quality has seriously influenced ecotourism and fishingindustries on which the people are dependent for their livelihoods. As a result, a restoration program was set up. One of the main aims of the project was to proposescenarios facilitating diluting the pollution level inside the bay and flushing pollutants out of it so as to improve water quality. As the ability of a body of water to disperse and flush pollutants is mainly dependent on water input [1], increasing water exchange rate between the bay and Caspian Sea by either opening artificial inlets or dredgingexisting channels was proposed. The effectiveness of different scenarios was assessed by investigating their impacts on transport time scale, described by residencetime, and accumulated water exchange between the sea and the bay [2].