Gully Remediation Effectiveness

 

Rebecca Bartley

Led by: Dr Rebecca Bartley, CSIRO

 

Project Summary

There is significant Government investment in water quality improvement focused on reducing gully erosion (~$50M), however, there is limited measured data to demonstrate the effectiveness of the remediation approaches. This project is collecting land condition, terrain and water quality data from five gully remediation trial sites in the Burdekin catchment. These data will demonstrate if the on-ground investment programs are actually improving measured water quality, and quantify the cost-effectiveness of the various approaches. The measured field data will be extrapolated using Lidar, which will support the prioritisation and evaluation of future remediation sites over larger (whole of property) scales. Communication products developed will provide the evidence needed to increase landholder engagement in remediation programs that are focused on improving water quality runoff to the GBR.

 

Project Description

Context and problem being addressed

  • Gully erosion contributes ~40% of the excess soil erosion to the GBR from just ~0.1% of the catchment area, however, the methods for reducing this erosion source are not well tested in the GBR catchments.
  • There is significant Government investment in GBR water quality improvement focused on reducing gully erosion (e.g. ~$40M from Reef Trust ~$10m from Qld Govt), however, we don’t currently have sufficient measured data to demonstrate effectiveness of remediation options. There is an urgent need to evaluate the most cost-effective methods for reducing the sediment and particulate nutrients generated and delivered from this erosion source.
  • This study is evaluating the effectiveness of a range of remediation options across different soil types and remediation approaches. The project has focused on collecting measured water quality data from five paired (control and treatment) gully sites on commercial grazing properties in the Burdekin catchment. Water quality data from these sites has also been shared with projects working on geochemistry, marine sedimentation and nutrient bio-availability in an effort to link catchment processes with marine impact.

Project Outline – extension component (2018-2020)

  1. Continued data collection from established field sites to support an improved understanding of the processes, timeframes, water quality improvement and overall estimates of cost-effectiveness of gully remediation activities.
  2. Development and application of an approach for the automatic detection of gullies from Lidar products. This will allow (i) the development of metrics (e.g. catchment area, gully width and depth) for prioritisation of sites within a property; (ii) baseline conditions to be assessed prior to remediation; and (iii) terrain metrics to estimate gully volumes and potential sediment savings from remediation investment. [Note that we will not be using the data to develop a gully typology as per Project 4.9. We are interested more in site identification and evaluation].
  3. Publication of the results from the field trials and terrain analysis into reputable journals. This demonstrates science quality and provides investors with the evidence to support (or not) on-going investment in gully remediation.
  4. Co-development of synthesis and communication products that enable the above information to be translated into communication and/or modelling products (to be done in collaboration with other NESP projects) – noting that some additional funding may be required depending on the type of products needed (i.e. no $ are available for professional communication videos or glossy products).

How the project will inform decision making on the ground

This project will have several important outcomes:

  • Rigorous (published) research will provide new knowledge quantifying the links between gully remediation, ground cover, erosion rates and water quality response to verify assumptions in P2R modelling scenarios and to quantify the cost-effectiveness of gully remediation strategies for Reef Trust and MIPs projects (via Queensland Dept of Natural Resources and Mines, DNRM modeller, Cameron Dougall).
  • Provide the Reef Trust gully remediation calculator with scientifically defensible (and published) metrics on the relative cost-effectiveness of gully remediation across a range of landscapes (which will be fed directly into the Reef Trust calculator).
  • Provide active field sites that can be used to engage with graziers, extension officers and NRM staff to demonstrate the practical on-ground management considerations for remediating degraded landscapes.

 

NESP 2017 Research Priority Alignment

This project aligns with Theme 1: Improved understanding of the impacts, including cumulative impacts and pressures on priority freshwater, coastal and marine ecosystems and species.

 

Project Keywords

Gully erosion; Remediation; Water quality.

 

Project Funding

This project is jointly funded through CSIRO, Queensland Department of Environment & Science (Landscape Sciences) and the Australian Government’s National Environmental Science Program.

 

Project Publications
Journal Article
Technical Report
Factsheet

 

 

 

International Symposium on Gully Erosion, 21st-27th July 2019, Townsville
Poster

 

https://eatlas.org.au/nesp-twq-5/gully-remediation-effectiveness-5.9