● Grazing management following rehabilitation needs to be carefully considered and monitored to ensure treatments are not compromised in the future .
● Due to the variability in erosion rates within and between gully types , cost-effectiveness values will vary between sites , even when the same treatment is used . The key to ensuring remediation resources are allocated cost-effectively is ( i ) to match the treatment value ($) proportionally to sediment loss , and ( ii ) prioritising sites with high baseline erosion rates , and high delivery to coastal systems .
● Due to the high variability in rainfall and site characteristics in these landscapes , whenever possible , M & E measurements should be collected from both control and treatment sites for at least one , preferably two wet seasons prior to rehabilitation works being undertaken . This provides much greater statistical power to detect and quantify changes in shorter time frames . It also provides a buffer which reduces the significance of data gaps that may occur ( for example from instrumentation malfunction or access limitation for sample retrieval ), which do occur in these challenging and remote conditions .
● Some sites are more suited to quantitative evaluation of rehabilitation effectiveness than others . It is important to have comparable treated and untreated control gullies ( e . g . the same soil , vegetation , rainfall , terrain , morphology , instrumentation ) otherwise monitoring design and site selection may introduce additional bias into the statistical analysis that reduces the ability to detect a change .
● This type of M & E will continue to deliver improvements in understanding for many years as an increasing range of climates are experienced and as the composition of revegetation continues to develop . These studies require a high level of expertise , and a lot of luck with respect to rainfall and instrumentation behaviour , to produce reliable results .
● While the quantitative data on sediment reductions will continue to emerge , the qualitative information such as terrain monitoring of gully erosion , photographs of event runoff , vegetation responses and treatment intactness provides early information to support gully rehabilitation .
● The P2R program has been modelling possible / potential water quality improvement following land management rehabilitation for more than a decade ; however , there is very little measured data available to constrain model predictions . This study presents some of the first control / treatment field experiments that are measuring changes in water quality on the ground . The data from these projects will be critical for scenario analysis using the P2R modelling which is currently being updated for the BBB .
● There is a need to resolve the difference in sediment yields being generated using the different techniques at each site ( flow monitoring vs terrain approaches ). This will likely occur as more data is collected from a range of rainfall and runoff events , however , some specific analysis of before and after treatment LiDAR data should be conducted to address this issue .
● Further work is needed to increase the proportion of native vegetation species included in gully rehabilitation projects , particularly in the sourcing of mixes containing a proportion of native seed for revegetation . Most of the sites are using rehabilitation species that are also very suitable for grazing and animal production which strongly suggests that these sites will be returned to production , rather than stabilising and managed as rehabilitation landscapes into the future . It would be valuable to evaluate the sustainability of these sites when production returns in future studies .
● Contemporary erosion rates ( t / ha ) can differ considerably from longer-term historical erosion rates , such as those measured from aerial photos . For example , it appears that recent erosion at
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