Molongolo Floodplain Rehydration Initiative

Hydrological modelling from a section of the Molonglo River Floodplain used to inform the rehabilitation design process.

The Molonglo River floodplain was once an intact valley floor with a discontinuous braided watercourse containing a complex of wet and dry grasslands, ponds and wetlands. 

Green and Golden Bell Frog
Image: G. Little, Australian Museum

Despite the impact of European settlement through agriculture and mining, it remains home to the last known population of Green and Golden Bell Frogs in the Southern Tablelands. One of the key goals of this rehydration project is to increase the frogs’ available breeding habitat with the hope of facilitating an expansion of the population. 

The extensive Molonglo Floodplain Rehydration Initiative in Carwoola, NSW will repair an 11km stretch of the Molonglo River with the goal of rehydrating and regenerating the adjacent 4,000ha floodplain, making it more resilient to drought and climate change. These works will help to re-establish habitat for the Green and Golden Bell Frog through in-stream and floodplain structures, rehabilitated wetlands, revegetation and regenerative land management. In parallel, it is also envisaged that the reinstatement of historical surface and groundwater flows along the floodplain will help to enhance the long-term resilience of primary production in the valley.

Planning, design and the approvals process is well underway, with the design process involving working closely with the supportive landholders of Carwoola and Foxlow, incorporating the long-term monitoring and management recommendations of frog experts Will Osborne and Sam Patmore, and drawing on hydrological modelling by Tim Morrison of Catchment Simulation Solutions to inform structure placement and size to achieve a more regular flood frequency, suited to frog breeding requirements. 

Special acknowledgement goes to the team at Catchment Simulation Solutions, Tim Morrison Senior Waster Resources Engineer and Prawi Woods Water Engineer, who have assisted with the development of spatial hydrological modelling to inform how our work can contribute to the hydrological regime required by the Green and Golden Bell Frog and to assist stakeholders in seeing where water flows across the floodplain, pre and post proposed interventions.

Learn more about the Green and Golden Bell Frog thanks to the Australian Museum.