A two-stage decision support tool for restoring tidal flows to flood mitigation drains affected by acid sulfate soil: case study of Broughton Creek floodplain, New South Wales, Australia

A 2-stage flood estimation and water quality decision support tool (DST) was developed, calibrated, and applied to a field site in south-eastern New South Wales (NSW) to simulate tidal restoration in a flood mitigation drain affected by acid sulfate soils leachate. The first stage of the DST employes a digital terrain map, geographic information tools, and measured water levels to calculate drain water overtopping due to tidal variations. Simulations using the GIS technique at the study site indicated that the primary drainage network can safely accommodate full tidal flushing (0.91 m AHD or a 58% increase), whereas at the same level the secondary drainage network overtops along relic drainage channels.