The Challenge

As part of implementing the Basin Plan, the Murray-Darling Basin Authority (MDBA) is proposing to develop a Constraints Management Strategy to investigate and implement ways to get better environmental watering results for wetlands and rivers through addressing physical and operational management constraints. Seven focus areas in the Basin have been identified where the relaxation of constraints needs detailed consideration including the Gwydir floodplain. Most of the land within the Gwydir focus area is used for agriculture, mainly cotton, wheat and grazing. OEH currently delivers environmental flows to high-value ecological assets along the system and wetlands in the Gwydir. Due to the small channel capacity of the rivers and creeks, some environmental water is carried overbank and has the potential to inundate agricultural land which can have positive or negative impacts.

Approach and Outcomes

Four flexible mesh MIKE FLOOD models were developed for the Gwydir floodplain to inform the Constraints Management Strategy. The models were used to determine inundation extents for a range of flow scenarios and inform where physical constraints are causing flood redistribution impacts. The modelling will also assist in identifying proposals, such as easements, to aid delivery of environmental flows in the Gwydir focus area.