Modeling water exchange using random walk method and its application in tianjin coastal region

Water exchange is important to study the solute transport pathway, to assess the self-purification capacity and to predict the water quality in estuarine and coastal waters. In this paper, a method to study the water exchange characteristics was presented, modeled with the random walk method and expressed in the form of water exchange matrix. Then the method was applied to the environmental impact assessment of brine discharge from desalination plants and to look into the water exchange characteristics in Tianjin coastal region. Moreover, based on the results, the potential impact of the discharged waste water on the water quality in each sub-area was discussed and the region suitable for setting desalination plants was suggested, so as to diminish the adverse impact on the marine environment and balance fulfilling the fresh water demand with environmental protection.