Restoring waterways cost-effectively

How and at what cost?


Key messages:
  • We document how to maximize the return on investment in freshwater conservation with limited financial resources under future climate and land-cover change scenarios.
  • Riparian restoration is the most effective adaptation strategy to climate change and urban development, but it is expensive
  • Farm and land management along with stream and riparian restoration are the most cost-effective strategies for freshwater biodiversity conservation

Riparian vegetation along Brisbane River. Queensland’s waterways provide over $10 billion annually in economic benefits.

Riparian vegetation along Brisbane River. Queensland’s waterways provide over $10 billion annually in economic benefits.

Southeast Queensland’s waterways provide over $10 billion annually in economic benefits through drinking water supply, fishing, tourism, and recreation (see the Healthy Waterways Report Card 2015). But these goods and services are under threat from intensive agricultural, urban development and climate change. It is clear that restoration is essential to protect biodiversity and improve flood and climate protection, but what should we do under a growing population and at what cost to maintain the quality of benefits from our waterways?  Working with researchers from Griffith University, Healthy Waterways and the Queensland Government, we recently documented how to maximize the return on investment in freshwater conservation with limited financial resources under future climate and land-cover change scenarios (MantykaPringle et al, 2016). The team focused on south-east Queensland as it is the fastest growing region in Australia and has less than 25% of its native vegetation remaining.

Restoration is key but costly

Stream and riparian restoration (fencing out livestock, bank stabilization, weed removal, replanting native vegetation, and expanding floodplain areas) provide the greatest protection to freshwater biodiversity in response to climate change and/ or urban growth (see Decision Point #78). However, when one also considers the costs of management actions, farm and land management along with stream and riparian restoration are the most cost-effective strategies for freshwater biodiversity conservation. Farm and land-management include activities such as pasture rotation, erosion reduction through smart burning practices, and better management of pesticides and nutrients. Managers identified that the cost of fencing for stream and riparian restoration can vary between AU$10,000-15,000 per kilometre. Revegetation can cost around AU$30,000-40,000 per hectare. Stabilization of banks and the construction of chutes/ stepped weirs to transport runoff can also be very costly.

The cost of farm and land management on the other hand, is cheap by comparison. In many countries, government policy relies heavily on voluntary arrangements, education and information as the main policy instruments through which to persuade landholders and community groups to adopt better environmental management.

Better bang for your buck

So, changing farm and land-use practices in the broader catchment can improve water quality (eg, reduce nutrients, pesticides and sediments) ‘cheaply’, but overall these may only have a modest effect on biodiversity – especially if the riparian land is degraded. The Queensland Government has worked hard to improve the environmental condition of its waterways by managing pollutant loads through better urban and rural management and engaging with community members.

As a result we have seen improvements in a few catchments, but a legacy of long-term riparian clearing in others continue to result in poor grading of water quality (see the Healthy Waterways Report Card 2015). Yet, many lessons can be learnt from south-east Queensland for our neighbors and especially the sustained management of the World Heritage Listed Great Barrier Reef (GBR). For instance, in order to improve water quality reaching the GBR, we cannot just target best management practice programs for the sugar cane and grazing industries located in the upper catchments of North Queensland.

Instead, to achieve the greatest bang for buck when it comes to waterway protection, conservation efforts need to first focus on protecting areas where the riparian cover is in relatively good condition and then on re-vegetating the stream network in partnership with best farm and land management practices.

Together, these actions will buffer pollutants from entering the freshwater and marine environments and provide better protection for biodiversity under climate change and urban development. Private landholders could also benefit financially as restoring riparian land could provide an alternative income through carbon farming.


More info: Chrystal Mantyka-Pringle c.mantyka-pringle@usask.ca

Reference

Mantyka-Pringle CS, TG Martin, DB Moffatt, J Udy, J Olley, N Saxton, F Sheldon, SE Bunn & JR Rhodes (2016). Prioritizing management actions for the conservation of freshwater biodiversity under changing climate and land-cover. Biological Conservation 197: 80-89. http://dx.doi.org/10.1016/j.biocon.2016.02.033

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