Table 6 . Predicted cost ($/ t ) of sediment reductions of Goldfields land type – 0 tree basal area .
Start condition ( Cleared )
Cost to reduce sediment ($ per tonne ) Pasture utilisation rate (% TSDM )
15 20 25 30 35 40 45 50
C |
4.97 |
14.14 |
7.39 |
2.98 |
1.35 |
-2.32 |
-6.16 |
-10.10 |
B |
62.76 |
82.10 |
46.95 |
30.23 |
20.19 |
14.07 |
9.56 |
3.22 |
A |
572.76 |
523.34 |
293.60 |
190.68 |
122.23 |
88.96 |
67.05 |
49.31 |
The range of cost per tonne of sediment from different land types highlights the risk of investment in sediment reductions . This is due to the dynamic nature of grazing production and the difficulty within a season to specifically target a particular pasture utilisation rate .
More recent work by Star and others ( Star et al . 2015 ) has refined the assessment of opportunity cost per tonne of sediment reduction for scenarios shifting from B to A and C to B hillslope management practices ( Figure 26 ). The costs for sediment reduction are higher for shifting from B to A practice than C to B practice , and for the BBB sub catchments , range from around than $ 20 per tonne in the Bowen River sub catchment for shifting C to B ( hillslope ), to $ 25 per tonne in the Little Bowen River sub catchment . Interestingly , the cheapest reductions would be achieved in the Bowen catchment ( typically less than $ 30 per tonne ), however , hillslope erosion is only part of the soil management issues and gully erosion dominates in these landscapes .
Figure 26 . Estimated opportunity costs per tonne of sediment reduced for shifting from B to A and C to B hillslope management practices in the top 20 sub catchments for sediment reduction across the Burdekin region . The Bowen , Broken , Bowen , Pelican Creek , Little Bowen Rover , Glenmore Creek and Rosella Creek sub catchments are all within the BBB catchment . Derived from Star et al . ( 2015 ).
Gully erosion management The costs of gully erosion management vary considerably depending on the specific characteristics of the gully formation , and the combination of management options . Wilkinson et al . ( 2015a ) assessed a number of practice combinations in terms of cost and sediment reduction , shown in Table 7 . The reductions in yield were estimated by comparing the anticipated effects of specific techniques with those used in previous fully remediation studies ( see Wilkinson et al . 2015a , Table 7 ). Generally , more intensive practices ( combinations 4 and 5 ) are less likely to be cost-effective unless infrastructure is threatened , and one cost estimate for reshaping and associated revegetation is $ 375 per tonne of sediment ( Shellberg and Brooks , 2013 ). However , engineered check-dams can be
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