Details

Autor(en) / Beteiligte

• Fryirs, Kirstie
• Zhang, Nuosha
• Ralph, Timothy J.
• Arash, Amir Mohammad

Titel

Natural flood management: Lessons and opportunities from the catastrophic 2021–2022 floods in eastern Australia

Ist Teil von

• Earth surface processes and landforms, 2023-07, Vol.48 (9), p.1649-1664

Ort / Verlag

Bognor Regis: Wiley Subscription Services, Inc

Erscheinungsjahr

2023

Quelle

Access via Wiley Online Library

Beschreibungen/Notizen

• Natural flood management (NFM), a nature‐based solution to flood mitigation where hydrological and biophysical processes are harnessed to reduce flow velocity, erosive energy and flood risk, is an emerging global theme of water and river management. The catastrophic 2021 and 2022 floods in eastern Australia are used to assess the hydrological properties of discrete events and to start an investigation of whether widespread changes in flood hydrology are occurring. We find that most coastal rivers in New South Wales (NSW) had a noticeable decrease in flood wave celerity (increase in flood travel time) when the 2021 and 2022 floods are contrasted with equivalent floods since the 1970s and that several also exhibit increases in flood peak attenuation. For some rivers, there is a coincident trend between these changing flood properties, riparian vegetation regrowth (regreening) and geomorphic recovery over the last +30 years. These may be the first signals that passive riparian management is counteracting some of the more severe hydrological effects of floods on these rivers and that some degree of NFM is possible. Lessons from this work are that there is an immediate opportunity to implement large‐scale NFM in coastal catchments of NSW, but this will only occur if we re‐examine current flood mitigation and adaption strategies and recognise and prioritise nature‐based solutions that include space‐to‐flood and corridors of river recovery, as essential parts of the modern flood mitigation toolkit. The 2021 and 2022 floods in eastern Australia are amongst the largest on record. We find the first signals that Natural Flood Management (NFM) is occurring coeval with significant changes in riparian and instream vegetation roughness since the 1970s. Flood are getting slower (celerity is decreasing), but they are not yet attenuating downstream (stage heights are not lowering). Opportunities are available to use NFM as a flood mitigation tool in these systems.