The method applied was developed after a comprehensive literature review of contemporary condition assessment methods for urban waterways.
Section 2.2.2 of this resource is, to HCCREMS knowledge, the most current, detailed and publically available review of condition assessment methods for urban waterways in NSW - providing descriptions of the National River Health Program's AusRivAS method; River Styles framework; and many others.
The study developed and applied a multi-criteria process to assess waterway condition, and assign each waterway a condition rating. Three desktop regional scale condition assessments were undertaken, as follows.
1. To categorise the region's diverse range of stream types a variant of the River Styles (TM) framework was used. Section 2.3 of the report details how River Styles was varied to accomodate the limitations of desktop analysis methods (as resources were not available to effectively conduct field inspections across such a large study area as part of this project).
2. Riparian vegetation condition was assessed based on indicators that included buffer width, continuity, protection status, catchment context and weed density. Further details are given in section 2.3.2, along with aerial photos that illustrate each of the nine 'states' of vegetation condition employed by the study. These states range from 'near intact-inside reserve' to 'good condition-high recovery potential' to 'no vegetation/flood control/recreation'.
3. An assessment of social values at the reach level was also undertaken, based on land use and other information that could be gathered through desktop analysis.
These assessments were complemented through a series of stakeholder and community consultation workshops.
By combining and considering the data and findings from each of the three assessments, a primary management action was generated for each reach, from a possible seven management categories for urban waterways (summarised below).
- Conservation / protection: Good condition sites, regarded as a high priority area for on-ground works. May require an increased protection status.
- Assisted regeneration: Good waterway structure and stability, with little potential for significant future erosion and good to moderate vegetation (some weed invasion). The primary focus for work is the implementation of a bush regeneration program.
- Revegetation: Buffer widths are sub-optimal. The creek may be experiencing some erosion and the riparian vegetation is not creating a significant corridor fauna passage or aquatic habitat.
- Geomorphic stability: This type of creek has a high susceptibility to adjustments, and protection of channel stability is important to maintain its current condition. Management options include bush regeneration, reducing catchment effective imperviousness or in-stream stabilisation.
- Geomorphic protection: High priority geomorphic landscape units that are very susceptible to change. Any change in the catchment will initiate a deleterious impact without significant intervention.
- Recreation: The creek is either in very good condition and is already protected in the reserve system, or, there are few natural values existing but it is in an area of high social activity. In both cases the focus is on improving sustainable access to the creek.
- Flood control: Channel is modified, with few environmental values. Unless it is a short reach between two exceptionally good reaches of creek the recommendation is to maintain it in the existing state.
The authors caution that the information developed through the study should be used at a regional scale, and more accurate assessments of actual condition require field based work. They recommend that a standard condition assessment method be developed for the project area, in order to provide a more robust basis for investment decisions. However, they suggest the study offers waterway managers a basis to identify broad scale priority areas for typical waterway management actions. The total initial estimated cost of such actions across the study area underlines the need for a basis to prioritise both management planning activities and investments to improve waterway condition.
The report recommends that the 'next steps' to progress this work would be to examine sites where 'good' condition reaches intersect with 'poor' reaches; and that any field visit inspection program should prioritise reaches in poor geomorphological condition.