Projects and Research
Water Balance Project 2016
The Friends of Big Swamp in partnership with the City of Bunbury and the Leschenault Catchment Council obtained a State Natural Resource Management grant, which allowed them to plan and implement a 12-month water monitoring program to assess the various water inputs and outputs, and thus identify the water balance of the wetland.
The water level has traditionally been maintained over summer through seasonal diversion of the adjacent Five-Mile-Brook into the swamp. The project essentially aimed to investigate the impacts of climate change on the water balance and the ecology of the wetland.
A complementary project was commenced shortly afterwards using a community grant from Worsley Alumina which allowed for sampling of the wetland for water chemistry analysis. The combined water balance and quality data has increased knowledge of the system and will inform management decisions into the future.
Volunteers collected monthly, weekly and daily measurements from groundwater piezometers, water level gauges and rainfall gauges, with photo monitoring and a series of relative height measurements to piece the data all together. Local hydrologist Heath Morgan of Strategen was appointed to generate the Big Swamp water balance model and make climate change predictions based on the data. The water inputs identified include the Five-Mile Brook diversion, rainfall and catchment runoff, and groundwater interaction.
Outputs include an outlet weir flowing back into the brook, evapotranspiration and evaporation as well as groundwater interaction. The project revealed the relative volumes of the major inputs and outputs to the swamp, and which of these are expected to change with a drying climate.
There is now an indication of water quality throughout the system as well as the source of nutrients into the wetland. Predictions have been made as to which areas of the wetland are likely to be exposed in summer and how this may affect the water quality and ecology of the wetland; and how various management decisions may positively or negatively impact on the characteristics and overall health of the wetland.
The project is an example of how community and local government can contribute to the design and implementation of useful projects with significant benefits to future environmental management.
The final report from Strategen is before the City of Bunbury and will be released in 2018.