Local groups say support and interest is growing for Nature-based Solutions (NbS) to be considered as a flood mitigation option for Lismore and to be included in the Flood Risk Management Plan.
Lindy Margan, a member of a committee that has been investigating flood options to decrease flooding in Lismore, says the group are interested in a new approach focused on NbS and have just released a document supporting this idea.
‘Nature-based is a long term project with great benefits for the community and the environment into the future,’ says Ms Margan. ‘It is certainly not a quick fix and can’t be rolled out shovel ready like some hard infrastructure projects that we’ve seen in the past.’
A review of 70 scholarly works
Dr Mitchell Kirby from Southern Cross University has recently written a literature review titled A Review into the Implementation of Nature-Based Solutions for Flood Risk Management.
Richmond catchment Landcare groups, Soilcare groups and Rous County Council, as part of the Northern Rivers Watershed Initiative, funded the document.
Dr Kirby has reviewed 70 scholarly works and investigated the flood damage reduction benefits from a range of catchment restoration strategies.
Nature-based Solutions can slow and store more water in the landscape by increasing riparian roughness, reconnecting rivers with their floodplains, through floodplain afforestation, wetland restoration and improved soil management. These were some of the strategies described as having flood height reduction success.
Ms Margan says that riparian roughness helps by planting out riparian areas with not only trees and shrubs but also lower growing plants such as sedges, rushes and lomandras creating a rough surface to slow the floodwater. ‘An added benefit is the variety of root systems underground. Fibrous to help mesh the bank together, tap penetrating deep into the bank to provide soil stability and dense mat roots stabilising lower streambank.’
Where to begin
Where to begin is the big question. ‘Firstly we get hydrological modelling done of the upper catchment. This means getting a consultant to map water levels during major rain events and the impact heights would have downstream if riparian areas were planted 20m either side of the banks’ says Ms Margan. ‘Then choose suitable sites for a case study.
‘This all takes money so we apply for grants with state and federal governments.
‘Not only does nature-based have the potential to decrease flooding but there are many co-benefits such as storing carbon, less topsoil loss, better pastures, increased habitat for wildlife/koalas, improved water quality and waterways for fish/aquatics, increased pleasure for recreational fishers/kayakers/rowers.
‘This means contacting all the interested groups who will benefit. Rous County Council, Farmers, Soilcare, NCMC, Macadamia Industry, FOK, OzFish, Landcare groups etc and get their support for this concept.’
Maintenance an ongoing issue
Ms Margan says maintenance will be an ongoing issue. ‘Depending on where the plantings are, every scenario will be different. If it is a farmer the potential to earn money from carbon capture and storage is a possibility and that could go into the maintenance. If it’s the macadamia industry less topsoil is lost so the investment in caring for their land is worth it. Landcare groups can support smaller landholders with grants and Lismore City Council has a Rural Landholder Initiative grant program that can help.
‘At the end of the day it is the landholder who has to do the maintenance and if they can see the benefits NbS provide, I believe they will be willing to put in the hard work.
In an advantage over traditional ‘hard’ mitigation strategies, such as drains and levees, nature-based solutions have a range of ongoing co-benefits.
Improved water quality and fish habitat, habitat and biodiversity improvements, reduced erosion and soil loss, increased climate change resilience, increased carbon capture and storage in the landscape.
In a recent Lismore City Council community survey into flood mitigation options, 93% of respondents registered their support for NbS as a flood mitigation measure.
For those who are interested in keeping up to date with discussions on Nature-based Solutions for flood mitigation in the Richmond river catchment, you can register your contacts at: www.surveymonkey.com/r/MVQ638W.