Gully Characterisation Framework to underpin GBR Catchment Water Quality Management
Led by: Assoc Prof Andrew Brooks, GU
In this project we will compile a database of gullies from across Queensland as a tool for communicating the diversity of gullies that exist in the landscape, but also the sommon elements from within this diversity, where they exist. Using this database we will develop a gully classification system to ensure that there is a common language used by researchers, land holders, land managers and practioners when identifying gullies for management intervention. This will also form the basis for subsequent automated gully mapping according to gully type. We will also develop a first order decision tool to guide land managers towards the sorts of management options that may be appropriate for the gullies in question. Whilst this will not be a design guideline, it will help to ensure that the range of management options are narrowed down by managers before specialist advice is sought. A checklist of design considerations will also be developed that will ensure that managers undertake the appropriate level of design work for the required intervention. To some extent this project will document and formalise the knowledge and decision making processes that are currently undertaken by the specialst technical advisory team to the Reef Trust Programme.
Gully rehabilitation and management is a high priority activity across all GBR NRM regions. Both the Queensland and Australian Government have recently invested significant resources into major gully rehabilitation programmes, through the Reef Trust 2 and 4 Programmes (AG); and the Qld Govt’s Major Integrated Project in the Bowen, Broken, Bogie (BBB), the Springvale Station Erosion Management Plan, and the gully innovation project (with Greening Australia). With these major investments (which in total amount to around $60M) there is a pressing need amongst all parties to identify different gullies in the landscape, and to priortise management effort and resources such that the appropriate treatments are applied to different gullies in the most cost-effective manner.
As more groups become involved in gully rehabilitation, and gully mapping, often involving people with little background in geomorphology, soil science or soil conservation, it is becoming increasingly obvious that before we can begin to develop gully management guidelines (the ultimate endpoint) we first need to ensure that we have a common language to describe the variety of gully types that exist in landscape. Not only is this important for developing management strategies, but it is important for mapping and priortisting gully management efforts. Catchment-wide gully mapping has been undertaken in each of the NRM regions, often using different criteria for what a gully is, and with no differentiation between different gully types. With additional information about different types of gullies in different parts of the landscape, resources can be much more efficiently targeted to the areas where they are most needed for water quaility improvement.
With this background in mind, this project will address the following research question:
Can a gully typology be developed that can serve the dual purpose of acting as a communication tool for non-experts to help them decide on appropriate rehabilitation strategies matched to the gully type and sediment source potential, as well as a basis for mapping different gully types in LiDAR data?
To achieve this the following will be undertaken:
- Compile a database of gully types from our own archive, from literature and from data provided by other specialists with experience working with gullies in Qld. The database will include a broad range of information on the different gullies, such that a non-expert user could identify a similar gully in the field (or from remotely-sensed data), based on reference to the gully database. Ultimately as the database is fully populated, users should be able to make some reasonable estimates of the relative sediment yield from the different gullies, and provide a preliminary assessment of the broad type of management strategy that might be applied.
The database will include* :
a. Broad gully type
c. Landscape context
d. Aerial images of the gully (if visible)
e. Ground images
f. LiDAR imagery of gully (where available)
Key metrics derived from liDAR data – e.g.
Gully area, length, width and depth
g. Catchment area
h. Soil type (where known)
Key soil parameters – where known (e.g. pH, EC, ESP, CEC, particle size, etc)
i. Sediment yield
2. Examples of channels that are not gullies will also be included, as will field characteristics to provide an indication of when a gully has effectively transitioned to a streamline..
3. A reference guide to indicators of gully activity.
4. Develop a classification scheme for the major gully types found in GBR catchments based on the range of gullies represented in the database (and Qld more broadly – i.e. building on previous work through NERP, MTSRF and TRaCK)
5. Derive a broad framework for the sorts of treatments that might be appropriate for rehabilitating the different gully types (with knowledge gaps identified where appropriate)
6. Develop a checklist of design requirements for the different treatments/gully types
7. Outline key knowledge gaps that will enable the development of a full design guideline for Queensland gullies (building on previous work by Bruce Carey).
(*NB – not all metrics will be availavble for all gully types at the outset, however gaps will be left in the database which can be subsequently filled as data becomes available).
NESP 2017 Research Priority Alignment
This project aligns with the NESP 2017 Research Priorities under Themes 1 and 2, namely;
Theme 1: Improved understanding of the impacts, including cumulative impacts, and pressures on priority freshwater, coastal and marine ecosystems and species
- Develop practical improvements to land management practices that will influence behavioural change and improve outcomes for tropical water quality and ecosystem health.
Theme 2: Maximise the resileinc eof vulnerable species by reducing other pressures, including poor water quality.
- Identify practical management actions capable of protecting and improving water quality on the Great Barrier Reef.
Gully database; Gully fieldguide; Gully classification.
This project is jointly funded through GU and the Australian Government’s National Environmental Science Program.
International Symposium on Gully Erosion, 21st-27th July 2019, Townsville