Figure 27 displays the results of stability achieved versus grazing land management for the treated catchments. The two catchment sites deemed to be under management with a low level of focus on land condition achieved stability but were on near-level ground; old floodplain terraces that only had banks installed to attenuate flows into gullies. The remaining 12 sites were on sloped land( above hillslope gullies). Of those that achieved stability, half were managed by graziers who were considered to have a high focus on improving land condition at the site.
Where the graziers had a moderate level of focus on improving land condition in the treated catchments there were a variety of results( stable to still active).
Figure 28 displays the results of stability achieved versus grazing land management for treated gullies. All sites had moderate or high ratings for the landholder’ s grazing land management expressed as‘ Focus on land condition’. Overall sites managed with a high focus on land condition performed better than those with a moderate focus.
One of the unstable sites( Site 22) had high grazing pressure by wallabies which is one of the factors leading to the poor result. Cattle were excluded from the site and the rest of the paddock was stocked lightly( cattle) and rested in the wet season. The one stable site that had a high level of pasture management, was in Downs country Vertosol soil. The eight gullies that received maintenance after construction are found across all categories: in levels of stability and in the landholders’‘ Focus on improving land condition’.
RESULTS- MAINTENANCE COSTS AND COST EFFECTIVENESS
A summary of the costs and cost-effectiveness, initial and following maintenance, for each project is summarised in Table 4. Note that only on-ground work is included. These costs do not include a range of additional costs such as site identification, project development and management, monitoring, maintenance, and reporting.
For the four large-scale sites where the gully was intensively remediated( Sites 1, 2 3 & 4) maintenance costs ranged from $ 10,644 to $ 48,231( Table 4). The cost effectiveness estimates, reported in the Burdekin Major Integrated Project, Year 4 Performance Report( NQ DryTropics 2022) have been updated in Table 4 to include the maintenance costs, however as uncertainty remains around the sediment estimates, these figures come with much uncertainty. Maintenance expenditure for intensively remediated sites( 1-4) ranged from 1.7-5.4 per cent of the initial project costs( Table 4, final column). The remaining large-scale site( Site 5), that had limited remediation work done on the gullies, had maintenance costs of $ 25,416; 9.9 per cent of the initial project cost. The sediment saving estimate for Site 5 was 922t annually which gives an updated cost-effectiveness of $ 306 / t, but this is almost certainly an over-estimate.
NQ DRY TROPICS 37