Gully 3
● Reshaping of the northern and central complex gully networks into two stabilised and free-draining basins that involves bank battering and topography reshaping through cut to ll-and-compaction earthworks operations .
● Reshaping of the southern complex gully network into a third stabilised and free-draining basin .
● Reshaping of a small alluvial gully adjacent to Basin 3 .
● Construction of three rock cut-o walls at the downstream extent of each of the three basin reshaping works . Construction of rock check dams in the beds of the three reshaped basins .
● Treatment of all the reshaped surfaces to consist of : - application and incorporation of gypsum to all reshaped and disturbed surfaces ; - spreading topsoil stripped from the footprint of the works ; and - applying soil ameliorants , fertiliser and drill seeding .
Gully 3 is a control gully for Gully 1 and also has CSIRO monitoring . Gully # 4 ( LRP17-022 Completed with Gully 2 )
Gully 4 is about 200 metres from Gully 2 . Gully 4 differs from the other gullies of interest on Glen Bowen Station , having an upstream catchment approximately four times the size of the gully ’ s footprint . The actively eroding footprint of Gully 4 has a perimeter of about 1.2km , with an internal area of 4.8ha . The banks of the gully scarp are on average 0.6m high .
The Gully 4 remediation design consists of the following works :
● Rock chutes designed to move flows to the bed of the gully and prevent future migration of gully heads from occurring .
● Earth bunds to be constructed on either side of each rock chute to direct cows to the crest of the rock chutes .
● Reshape the gully network into two stabilised and free-draining basins by battering banks and reshaping land features to reduce water flows and to prevent ponding occurring on the sodic and dispersive soils .
● The reshaping of shallow gullies and gully scarps to manage runoff . Construction of a series of rock check dams to help control flow velocity and to trap sediment allowing the structures to act as drainage and sediment control devices .
● Cover treatment will include cornet matting , hydromulch ( a slurry of water , seed , fertiliser , cellulosic mulch and binder that is sprayed on ), hay or bagasse ( depending on availability ) to achieve 50 % cover of the disturbed footprint prior to the wet season .
● Amelioration will also include spreading of an ameliorate mix of topsoil , fertiliser and gypsum , based on soil sample results .
Onsite vegetation , runoff and water quality data was collected by CSIRO , commencing in 2019 .
The water quality monitoring equipment was installed in early November 2019 and the terrain , pasture and biomass surveys were conducted in early December for the pre-wet analysis and April 2020 and 2021 for the post-wet analysis . There was no pre-wet vegetation survey conducted on the treatment gully as rehabilitation had already been initiated before the field data could be collected , It can be assumed that the land condition and cover metrics at the treatment gully were equivalent or similar to the control gully prior to rehabilitation .
The location of the treatment and control sites is shown in Figure 20 . The area of the catchment above the monitoring station is 2.7 ha for the treatment site and 2.9 ha for the control site .
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