Black soil site
Black soil site
( works implementation completed January 2018 )
Figure 28 : Black soil project site in relation to Tabletop homestead ( bottom left )
Background and implementation
The project area was a black soil gully contained in , at project initiation , a 1200ha paddock , with a 340ha paddock later subdivided around the project area . The main land types are narrowleaf ironbark on deeper soils , box country and clayey alluvial .
• The 1km gully has relatively stable landscape features of box country grassy woodland on either side of the feature .
• The gully was active from the 1960s with the outlet end stabilised on a rocky outcrop prior to discharge into a creek .
• A 200m section above the rocky outcrop was relatively mature , with limited side gully entry points , a flattening of the grade , and a more stable channel .
• The next 300m was very active following the formation of a secondary incision which had lowered the former gully by around 1.0m resulting in widening and straightening of the previous channel .
• A stock dam was later sited in this section once the gully diversion bank was completed .
• The 500m of gully above the secondary incision was stabilising in the lower sections with considerable deposition of sediment , a reduction in widening and improved batters on gully walls .
• The upper section of the gully was very active with gully heads severely eroding during late 2017 wet season conditions . New side cuts had formed and the channel was actively slumping and widening .
• Nine active head cuts had formed in the upper section of the gully .
Bob Shepherd , Department of Agriculture and Fisheries ( DAF ), Charters Towers recommended and supervised the construction of a 1300m diversion bank to reduce the volume of water moving onto the existing gully heads .
A level sill outlet , on a ridgeline , was constructed to safely dispose of the diverted water .
The majority of the earthworks was provided in-kind by the landholder - an estimated 130hrs of machinery time at a cost of around $ 26,000 . 66