Over 6500 hectares of sea grass have been lost from Adelaide’s coastal waters since 1949. This has had a negative impact on the environmental, community and economic values associated with St Vincent Gulf. Excess nutrients and turbidity (cloudy water due to suspended particles) were identified as the main causes of this loss. Nutrient inputs have now been significantly reduced and so the primary barrier to sea grass restoration is the input of sediment, particularly fine sediment.
While we understand where fine sediments are coming from, we don’t know which types of urban water management interventions are best suited to help stop fine sediments reaching the Gulf. This project will develop a decision support framework to help prioritise investment in urban stormwater water management interventions to reduce inputs of fine sediment to Adelaide’s coastal waters.
When developing the decision support framework, the team will:
• consider the effectiveness of different interventions, with a focus on known interventions rather than new interventions
• synthesise existing information on sources of fine sediment to the Gulf
• apply a multi-criteria assessment approach
• consider opportunities for co-investment across local and state government.
The framework will be tested and applied at a sub-catchment scale in the first instance but will provide capacity to allow it to be applied to all metropolitan Adelaide catchments in the future.
The framework will be complete by May 2020 to inform investment decisions by the South Australian Government.