Reshaping, gypsum, fertiliser, seed |
0 1 |
No Maintenance required |
Maintenance required |
Reshaping, fertiliser, seed 1 2
Reshape, seed 0 0
Contour line rehab – catchment 6 1
Rock chute 0 6
Porous check dams / weirs 7 3
Bund 0 0
Bank and spreader – catchment 31 4
Stick lines
3 0
0 5 10 15 20 25 30 35
Figure 16. The number of the structures and treatments at the 19 small-scale gully sites that required maintenance compared to those that did not.
Works in the catchment required less maintenance than works in the gullies. One of seven sites with catchment rehabilitation along contour lines required maintenance. This site( Site 19) was not prioritised for maintenance; it is a small site(< 0.5ha) in a remote area. In the initial treatment the site was ripped, fertilised and seeded very close to the gully edges; the rehabilitation failed in the area upslope of the gully heads, leading to further, and probably, exacerbated erosion. The rehabilitation was more successful on the treated side of the gully.
Only four of the 35 banks and spreaders installed in catchments required maintenance. One diversion bank breached during the first rains following construction and the landholder repaired it immediately, on Christmas Eve 2020, in-kind. The remaining three that required repair were all holding water against the bank rather than draining water away. Two were in Downs country Vertosol soil and one in dispersive Sodosol soil. The native land crab, that excavates burrows into banks and aestivates in them during the dry season, was found at two of the three sites— 1 vertosol and 1 Sodosol site( refer to Figure 33).
Three sites had treatments involving major soil disturbance( reshaping) to the gully itself, followed by soil ameliorants( gypsum and fertiliser or just fertiliser) and seeding. All sites that were highly disturbed required maintenance to address rill erosion. At one site( Site 12) the landholder responded quickly to the rilling that appeared in the first wet season, installing extensive rock and stick check dams( in-kind). The second site( Site 22) was repaired in 2024 and, by this late stage, rilling in the reshaped bowl was deep and starting to form gullies. Site 20, the less disturbed site( gully head fill and manure; Figure 6), seemed to be doing well with high and diverse vegetation cover but now it requires maintenance; during the 2024
28 GULLY MAINTENANCE AND MONITORING TECHNICAL REPORT