Replenishment of Forrestdale and Thompsons Lakes with stormwater
To consider the benefits and risks of potential replenishment of Forrestdale and Thompsons Lakes with stormwater from surrounding areas.
Conceptual modelling has shown that stormwater replenishment is a viable option for Forrestdale Lake and other similar wetlands and can assist in maintaining hydrological conditions that support the ecological character of the Lake. Further works are currently under consideration to implement stormwater replenishment at Forrestdale Lake.
This project has examined the viability of upstream catchment modification to increase stormwater flows into Forrestdale Lake. Research into adaptation strategies for important lakes is underway as a part of the CRC for Water Sensitive Cities research program and supplementation of the lakes with stormwater sourced from development in surrounding areas is under consideration. This project contributes to ongoing research in this area by considering the potential for supplementation from currently rural upstream catchments of Forrestdale Lake.
Drainage from rural land in the upstream catchments of Forrestdale Lake has historically contributed to the Lake but through changes to land management practices and reduced maintenance of the drains, as well as climate effects, regular contributing flows from these catchments have declined. Whilst it is recognised that urbanisation of surrounding land can ultimately deliver more significant inflows, the associated benefits and risks of impacts from these discharges need to be properly understood in order to appropriately manage more widespread adoption.
The project included the following specific phases:
- Review and characterisation of upstream contributing catchments including land use review, hydraulic and hydrological modelling, monitoring and establishment of baseline water quality.
- Identification of potential opportunities for modification of drains in existing contributing subcatchments and for expansion of the contributing catchment.
- Review of the impact of potential physical works to convert selected existing drains to living streams including clearing of sediment and weeds, modifications to cross section and longitudinal sections to increase flow rates, revegetation and integration of instream water quality treatment systems where necessary.
- Proposals for future works.
Project benefits & beneficiaries
- WA State government – the project is specifically aimed at delivery of commitments number 85, 88 and 89 of the State Government’s Green Growth Plan: Action Plan F MNES Conservation Commitments. The project has significant potential benefits to the environment within and surrounding these internationally important wetlands.
- Local Government – the project has the potential to provide significantly improved environmental and community outcomes by improving the long-term sustainability of these important natural assets and reducing requirements for creation of new constructed assets to manage water separately.
- Landowners – the project has the potential to significantly change the relationship between land development and natural environmental assets by providing landowners with practical ways to contribute to their long term sustainability.
We would like to than the following organisation for their valuable input and commitment to this project:
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