Recovery of Adelaide’s seagrass meadows

Seagrass has been disappearing from Adelaide’s coastal waters in the Gulf St Vincent, South Australia since the 1950s. The Adelaide Coastal Waters Study concluded in 2007 that the seagrass decline was caused by discharges of treated sewage, rivers and storm water, which reduce water transparency and further the excessive growth of “epiphytes” on the seagrass leaves. Both phenomena reduce the amount of sunlight penetrating to the seagrass leaves and subsequently kill the seagrass. At that time, however, it was not clear when, where, and by how much these discharges would need to be reduced to create the conditions required for recovery of the seagrass meadows. The South Australian Water Corporation (SA Water) commissioned Deltares to jointly develop coastal modelling capabilities that would help to answer these questions. With Delft3D as the main “engine”, SA Water, Deltares and DAMCO Consulting (Perth, West Australia) built the Adelaide Receiving Environment Model (AREM).