status and land tenure . This assessment narrowed the set of prospective sites to a final group of eight which were then assessed against the full set of site selection criteria . These include : Blue Valley , Glen Bowen , Hell ’ s Gate , Johnny Cake , Lower Bogie ( Kirknie ), Mid Bogie ( Strathbogie ), Mt Wickham and Riverview / Spring Creek . To date Glen Bowen has been selected for gully remediation . The project report contains full description of all these sites and the assessment against the selection criteria .
The following information has been directly extracted from the report prepared by Andrew Brooks and the project team from Griffith University ( Brooks et al ., 2018 ). The full report is available by contacting NQ Dry Tropics .
The objective of Stage 2 was to produce a high-resolution spatial map of active gullies , and where possible eroding stream banks , that will form the basis for a rehabilitation investment prioritisation for the BBB ( Stage 3 ) ( i . e ., beyond the life of the MIP ). There were four key parts to this stage :
• The delineation of active gully boundaries at a resolution of approximately 1m .
• The classification of the mapped gullies into a defined number of classes .
• The compilation of gully erosion rate data to begin the process of building a spatial database of gully erosion rates to underpin a spatial prioritisation according to relative sediment yield .
• The compilation of a gully soil materials database to underpin a spatial prioritisation based on physical and chemical soil material properties ( and ideally particulate nutrient status ) as well as sediment yield .
Outcomes :
• A semi-automated approach was developed to map gullies from LiDAR DEM data . A fully automated system was not possible at the time because of fundamental differences in gully types in different landscape settings ( this was addressed later in the project ).
• A wide range of approaches were trialled in the Mt Wickham LiDAR block ( a 323 km 2 LiDAR block captured for the LDC project in 2017 ). The method settled upon for the bulk of the mapping work is based on Multi-Dimensional Hillshade analysis . This method is computationally simple and can define continuous boundaries around discrete gully systems , sub-systems , and unit gullies . It is applied using different thresholds in different landscape units . This method is a much finer resolution ( 1m x 1m grids ) compared to the broader-scale active gully and channel erosion layer ( 100 x100m grid cells ) being used in the P2R catchment models ( see Figure 36 ).
• A range of methods were also trialled and evaluated for defining structures and complex landforms within the broadly defined gully boundaries . These metrics were evaluated as proxies for relative gully activity , to identify active gully systems or the active parts of individual gullies .
• Building on the work undertaken through NESP Project 4.9 , a set of morphometrics were defined that provided the basis for the roll out of the classification .
• A method for reconstructing the pre-disturbance 3D land surface was developed , which is critical for deriving volumetric changes in the gullies and hence sediment yields .
• Significant progress was also made on the reconstruction of gully growth rates at 7 sites on Glen Bowen and Strathmore stations . This type of data provided the core data for the development of the overall prioritisation framework .
• In addition to the Australian Government acquisition of LiDAR data across ~ 3,500km 2 of the BBB catchment , the repeat LiDAR archive held by Fugro-ROAMES who fly transects long all the power lines in the catchment for Ergon Energy (~ 700m wide swathe ) was acquired . The dataset contained
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