Post Conference Field Trip 26 - 27 July 2019 Lower Burdekin and Bowen River Acknowledgements Firstly, I would like to acknowledge the Birriah People, the traditional owners of the land we will be traversing over the two-day field trip. Thanks to the following for their assistance with the organisation of this field trip and the rehabilitation works at the various sites: Field Guide Authors: Andrew Brooks1, James Daley1, Justin Stout1, John Spencer1, Robin Thwaites1, Nic Doriean1, Damon Telfer2, Rebecca Bartley3; Glenn Dale4, Rod Kerr5 1 Griffith University; 2Fruition Environmental; 3 CSIRO; 4 Verterra, 5NQ Dry Tropics Field Trip Organisation: Tracey Rehbein and Amy Warnick, CSIRO To Strathalbyn Station landholders Bristow and Uriesha Hughes for facilitating the large-scale gully rehabilitation works on their property; to the Queensland Government and Greening Australia’s Reef Aid program for funding the gully rehabilitation trials; to Lynise Wearne and Sunny Behzadnia from Greening Australia for overseeing the project and for the monitoring equipment setup and sample collection (along with Damon Telfer); To Paul and Sally Fry from Strathmore Station; Owen and Michele Howard from Hell’s Gate Station & Warren Woodhouse from Mt Wickham Station; The rehabilitation at Mt Wickham Station was undertaken as part of the Qld Government/NQ Dry Tropics Land Holders Driving Change project. The project design and oversight were undertaken by the Verterra/Alluvium Joint Venture, and the monitoring was undertaken by Aaron Hawdon from CSIRO. A very special thank you to Clare and Ringo, our wonderful hosts at the Bowen River Hotel. And finally, to all our sponsors and collaborators as listed below. : The Conference Sponsors are listed at the end of this document. 2 | POST CONFERENCE FIELD TRIP | LOWER BURDEKIN AND BOWEN RIVER Program Day 1 (Friday 26th July) Townsville to Strathalbyn – via Tondara Rd 3.5 hrs driving + 15 mins rest stops Time Details 8:00 Depart Rydges Hotel Stop 1 11:45 Strathalbyn Station Gully Rehab Site Schedule on Site: 11:45 – 12:30 Introduction to Site & Background – Location - Site Office • A/Prof. Andrew Brooks – Introduction of Key Participants – incl. Landowner Bristow Hughes; Why this site was selected; Overall Significance of site to GBR Water Quality. • Dr Lynise Wearne (Greening Australia) – Background to Innovative Gully Project & Overview of Site Treatments; • Damon Telfer (Fruition Environmental) Detailed descriptions of Site Treatments and Monitoring Strategy. • Rod Kerr (NQ Dry Tropics) Cattle Stomping Project. Nic Doriean (Griffith University) Time integrated sampling. 12:30 – 13:00 Lunch 13:00 – 15:00 Damon Telfer/Rod Kerr - Tour of site with explanation of the various treatments and the issues confronted and lessons learnt with each along the way. 15:00 Depart Northern Gully Rehab Site Stop 2 15:15 Strathalbyn Black soil gullies 15:30 Depart Strathalbyn for Bowen River Hotel via Johnny Cake Road 17:00 Arrive Bowen River Hotel Figure 1 Overview of Strathalbyn Gully Rehabilitation Site October 2018, immediately post-construction (Andrew Brooks) | 3 Figure 2 Dawn at the Bowen River Hotel (Andrew Brooks) Day 2 (Saturday 27th July) Bowen River sites Time Details 8:00 Depart Bowen River Hotel Stop 1 8:05 Bowen River Hotel Airstrip alluvial gullies • Griffith University PrESM Team – overview of Semi-automated gully mapping and baseline sediment yield quantification Stop 2 9:15 – 10:30 Hell’s Gate Station Hillslope Colluvial gully systems • Welcome – Landholder Owen Howard. • Griffith University PrESM Team – Over of site & challenges associated with managing extensive distributed gully systems in Granodiorite colluvium. Stop 3 11:00 – 12:30 Mt Wickham Gully Rehabilitation Site • Overview of Site – Dr Glen Dale & Peter Wilkinson (Verterra) • Site Monitoring – Dr Rebecca Bartley (CSIRO) 12:35 Depart for Bowen River Hotel 13:00 – 14:00 Lunch 14:00 Depart Bowen River Hotel for Townsville – via Strathmore Road and Bowen Development Rd. 18:00 Arrive Townsville 17:00 Arrive Bowen River Hotel 4 | POST CONFERENCE FIELD TRIP | LOWER BURDEKIN AND BOWEN RIVER Figure 3 Location Map showing the sites visited during the field trip | 5 Overview and Introduction A warm welcome to you all on the 8ISGE Post conference field trip. Strap in for what will be, at times, a slightly bumpy ride on some back roads, where we will visit some unique gullied landscapes and experience some great Aussie country hospitality at one of the original old country pubs in the Bowen River district. As you have heard throughout the symposium over the last few days, poor water quality from catchment sediment and nutrient runoff is one of the major threats to the Great Barrier Reef (GBR), and a large proportion of this pollution (40-50 % on average) is sourced from gully erosion. In some sub-catchments this proportion is even greater than 50 % of the catchment sediment sources. Where we are heading on this trip is one of the major hotspots for gully erosion in the GBR catchments. Over the next two days we will be touring through the lower Burdekin catchment and into the Bowen River sub- catchment, which has been identified from both sediment-tracing and monitoring studies (Bainbridge et al., 2014) as being the highest sediment yielding sub-catchment in the Burdekin river, and indeed the entire Great Barrier Reef (Table 1). We also know that there are high concentrations of extremely active gullies in this catchment, and as such gully rehabilitation is a high priority within this area. During this trip we will visit two gully rehabilitation sites where we will see a broad array of different approaches that have been used to stabilise large alluvial gully systems (see separate document from Fruition Environmental). In addition, we will discuss the pros and cons of different gully treatments, as well as issues associated with scaling up these projects to such an extent that will make a quantifiable difference to sediment loads at the catchment scale. A big ask, considering the stated aim of the Australian and Queensland Government’s water quality targets for the Burdekin catchment by 2022 is to reduce mean annual fine sediment loads (< 20 µm) by 890,000 tonnes at the coast (Table 2)! Efforts to date have achieved perhaps 1% of this target. We will also visit a number of other sites to witness the diversity of gullies in the area and discuss some of the methods we are using to map the distribution of gullies, and to quantify their sediment yields. This is a key component in the unique challenges in managing the sediment loads from these very complex gullied landscapes. The team from Griffith University who are your hosts for the next two days, wish you all the very best on your gully tour through the backblocks of the Bowen River, and look forward to good times and many stimulating conversations. Best Regards, Andrew Brooks – Griffith University 6 | POST CONFERENCE FIELD TRIP | LOWER BURDEKIN AND BOWEN RIVER Table 1 summary of the relative contributions of various sediment size fractions from the Bowen and lower Burdekin to the Burdekin River outlet. Table 2 Reef 2050 Water Quality Targets (for 2025) | 7 Figure 4 Extent of gullies mapped across the Strathalbyn LiDAR block (2016) and underlying 1:100000 surface geology 8 | POST CONFERENCE FIELD TRIP | LOWER BURDEKIN AND BOWEN RIVER Figure 5 Extent of gullies mapped across the Mt Wickham LiDAR block (2017) and underlying 1:100000 surface geology | 9 Site 1 | Strathalbyn Station This site was identified from a 2015 aerial survey along the Bowen and lower Burdekin rivers as being an aggregation of active alluvial gullies within a relatively confined area (Figure 6). Closer inspection and subsequent analysis of the evolutionary trajectory of these gullies showed them to be producing large amounts of sediment. Figure 6 locality map – Strathalbyn Station Alluvial gully aggregation 10 | POST CONFERENCE FIELD TRIP | LOWER BURDEKIN AND BOWEN RIVER Figure 7 Map of the same gullies shown in Figure 6, showing the catchment area to each of the gullies. The active gully area is depicted in yellow | 11 10000 A 1000 100 YIELD (T/YR) 10 1 South_11 South_36 South_41 South_47 South_49 South_51 South_53 South_55 South_57 South_59 South_61 South_63 South_65 South_67 South_69 North_05 North_07 Central_27 Central_30 Central_38 Central_40 Central_42 Central_48 Central_63 Central_65 Central_72 Central_74 Central_76 Central_78 800 B 700 600 500 400 300 YIELD (T/HA/YR) 200 100 0 Central_… Central_… Central_… Central_… Central_… Central_… Central_… Central_… Central_… Central_… Central_… Central_… South_11 South_36 South_41 South_47 South_49 South_51 South_53 South_55 South_57 South_59 South_61 South_63 South_65 South_67 South_69 North_05 North_07 Figure 8 Graphs of the mean annual sediment yield from the 29 gullies shown in Figure 6(A) and the specific sediment yield (B). Note the disparity between total and specific yield. 20 y = 0.5469x0.8145 R² = 0.9802 15 10 gully area (ha) area gully 5 0 0 20 40 60 80 100 gully catchment area (ha) Figure 9 Relationship between active gully area and gully catchment area at the Strathalbyn site (as per Figure 7) 12 | POST CONFERENCE FIELD TRIP | LOWER BURDEKIN AND BOWEN RIVER Historical Sediment Yields – Strathalbyn Gullies 2016 1985 1972 2013 2003) + Google Earth imagery (2013) and LiDAR (2016) of the northern gully group. – 1956 2003 Historical airphoto sequence (1956 10 Figure Figure 10 Historical airphoto sequence | 13 Figure 11 Digitised changes in gully area for the historical airphoto sequence (1945 – 1995) and LiDAR extent for the 2016 time slice in the northern gully group showing the growth of the gullies over the last 72 years. 14 | POST CONFERENCE FIELD TRIP | LOWER BURDEKIN AND BOWEN RIVER B A Figure 12 DEM of Difference (A) derived from the reconstructed gullied landform (B) | 15 Table 3 Mean annual sediment yield derived from the historical reconstruction of the gully expansion ( 70 y = 10.087e4E-05x 60 R² = 0.9929 Total 50 North Central 40 South 3E-05x Hectares 30 y = 6.9089e Expon.