Assessing the multiple benefits of waterway management

Waterway management projects often comprise specific site scale management interventions such as structural works (i.e. bank reprofiling and pile field toe protection), revegetation, and fencing for stock exclusion. These waterway management projects are generally implemented to achieve a singular objective (i.e. protect an asset, or reduce sediment loss) which tends to focus investment to small scale localised areas (i.e. an eroding bank).

In contrast, well planned and implemented reach-scale waterway management programs can provide a range of benefits including biodiversity outcomes, water quality treatment, flood mitigation, carbon sequestration, and recreational and amenity outcomes. However, often these benefits are difficult to value which makes it hard to target investment or support business cases.

One challenge is that the scale of these benefits varies from catchment to catchment, and from reach to reach. In addition, the benefits fall into diverse categories (private/public, longterm/short term, ecosystem/economic, local/upstream/downstream). Furthermore, several benefits are not monetised or traded in prevailing markets, which complicates assessments to provide evidence in seeking private or public funding. As a result, it is difficult to set priorities when making decisions about where to work and what to do.

What services do waterways provide?
Riverine, and floodplain, ecosystems support a rich array of biodiversity and play an important role in supporting human wellbeing by providing numerous benefits including the provision of food and water, and the regulation of extreme natural events. River-floodplain ecosystems are subject to seasonal inundation by lateral overflow; these flood pulses promote a mosaic of habitats from riverine to terrestrial. Due to the ecological functions of riparian zones, and its role as a transition zone between riverine and terrestrial ecosystems, riparian zones have the capacity to deliver a disproportionate amount of ecosystem services relative to its extent in the catchment.
Waterway management measures, such as riparian revegetation programs, have the potential to provide multiple benefits such as improved water quality, habitat improvement, ecological corridors, avoided damage to infrastructure, and eco-tourism improvements (Figure 1).


Figure 1. Conceptual model of the Mackay-Whitsundays regional riverine ecosystem showing the relationship between critical components, processes, and benefits.

The effect of management measures on ecosystem services provision
We developed a framework for assessing the effect of management measures on ecosystem services provisions. Nine management measures, ranging from vegetation-based management to structural interventions, were selected for the project. We then developed a comprehensive list of benefits which result from waterway management actions (24 in total).

The effect of each management measure was scored, based on academic research and expert opinion of the project team from -1 (negative impact) through to 2 (highly positive benefit). Overall, management measures which constitute vegetation management were found to provide the most positive benefits, across are wide range of ecosystem services.

Approaches for the economic evaluation of waterway services
We identified approaches to measure the benefits of the waterway management actions identified in this project, along with data requirements and possible limitations in quantifying these benefits.

To determine appropriate valuation approaches, we first considered the type of economic value (e.g. direct/indirect use) for the specific ecosystem service. Based on the type of economic value we then identified the most suitable valuation approach for each ecosystem service for example using secondary data, inputs into an approach like market price or a cost-based method, or using benefit transfer.


The value of region wide riparian revegetation in the Mackay-Whitsundays

Seven ecosystem services were selected for valuation in the region (Table 1).

Table 1. Summary of services, and benefits for humans, valued in the Mackay Whitsundays region.

Value of benefits
The value of benefits associated with catchment scale revegetation was compared against the base case (current) situation (Table 2). Erosion control and tourism returned the greatest benefit; $111 million and $52 million respectively.

Table 2. Benefit valuation under the base case and the reference case.

A cost-benefit analysis (CBA) was then undertaken to estimate the of the ratio of benefits to costs of catchment scale revegetation (Table 3). A benefit-cost ratio (BCR) greater than one indicates that the benefits outweigh the costs, and the investment is economically viable.

The initial assessment returned a BCR of 0.65, indicating that the investment is not economically viable, as the benefits fail to justify the associated costs. However, an additional scenario was assessed, incorporating the potential cost advantages resulting from the project’s scalability. For this scenario, the same initial capital costs were used, while the establishment period maintenance was reduced based on considerations of efficiencies that could be achieved from implementing large scale revegetation works. Using these costs a much-improved BCR of 1.55 was achieved. The BCR result indicates that the benefit categories would economically justify the cost of investment and would incur a gain of $76 million.

Table 3. Cost-Benefit Analysis results

While the initial BCR indicated the program was not financially viable this is likely highly conservative as:

  • Costs are based on smaller projects from local suppliers whose businesses have not been developed to implement large scale revegetation programs. There are often issues with plant supply, staff shortages and lack of equipment for these smaller projects which all tend to increase the cost.
  • Not all benefits have been accounted for in this higher-level study. The additional benefits associated with ecological connectivity, recreational and commercial fisheries, flood mitigation, land productivity and asset protection are likely to add to the total benefits significantly.

Key outcomes
Region-scale riparian rehabilitation is required to help protect biodiversity, threatened species, water quality and floodplain productivity. However, it is likely that multiple funding streams from various beneficiaries will be needed. The economic benefits identified within this study can help in the planning of future steps to help achieve the desired outcomes.

More Information

This project was delivered by Alluvium Consulting and Natural Capital Economics, in partnership with Reef Catchments.  For more information contact Misko Ivezich (