Millions of dollars are being spent on gully rehabilitation to help reduce excess fine sediment delivery to the Great Barrier Reef(GBR).There is an urgent need for(i)prioritisation of active gullies for rehabilitation...Millions of dollars are being spent on gully rehabilitation to help reduce excess fine sediment delivery to the Great Barrier Reef(GBR).There is an urgent need for(i)prioritisation of active gullies for rehabilitation and(ii)the development of methodologies to inform the effectiveness of remediation.In this study we analyse DEMs of Difference derived from 0.5 m resolution 2-3 year interval multi-temporal LiDAR data collected pre and post rehabilitation at three variable gully morphologies in the Burdekin catchment.Our analysis indicates that the highest annual average fine sediment erosion rates for the untreated control gullies occur at the linear gully(53.38 t ha^(-1)y^(-1))followed by linear-alluvial gully(34.24 t ha^(-1)y^(-1))and least at the alluvial gully(14.41 t ha^(-1)y^(-1)).The proportional loss or export of fine sediment from the gullies in their un-treated condition ranges from∼68 to 90%of what is eroded,and when the gullies are treated the proportion of fine sediment that is retained in the gully proportional to what is eroded increases to∼60%at all sites.Without pre-treatment baseline erosion rates,and additional post treatment LiDAR captures,it is difficult to quantify the treatment effectiveness.Our results offer insights in the erosion mechanisms within different geomorphic gully morphologies and rehabilitation effects in these erosional landforms.This study provides crucial knowledge of gully dynamics that can be coupled with other lines of evidence for better prioritisation of rehabilitation in the GBR catchments.展开更多
Daley et al.(2023a)argue that at least 10-15 years apart Digital Elevation Model(DEM)derived DEMs of Difference(DoD)surveys are needed to detect reliable geomorphic change within the gullied landscapes of the Great Ba...Daley et al.(2023a)argue that at least 10-15 years apart Digital Elevation Model(DEM)derived DEMs of Difference(DoD)surveys are needed to detect reliable geomorphic change within the gullied landscapes of the Great Barrier Reef,Australia.We acknowledge that the reliability of observed geomorphic change increases as more subtle geomorphic processes are detected with longer monitoring periods.As further good quality long-term legacy datasets become available,we encourage utilising these to improve confidence in targeting erosion rehabilitation.However,our approach to consistently apply 2-3 year DoDs to contrasting gully morphologies enabled capture of more intense geomorphic processes acting over shorter timeframes and provided valuable and timely information on(i)contrasting erosional mechanisms and erosion rates between variable gully morphologies,and(ii)rehabilitation efforts un-dertaken.In this paper,we take the opportunity to concisely address all the concerns raised by Daley et al.(2023a).展开更多
基金We would like to acknowledge the Australian Government Reef Trust GBR LiDAR Project(Environmental Research and Analysis Project SON2615371)the Australian Governments National Environmental Science Program(NESP)Tropical Water Quality Hub Projects(Projects 2.1.4 and 5.9)+1 种基金the Queensland Government funded Landholders Driving Change(LDC)Program(LRP17-003 and LME17-009)CSIRO for providing funding for this study.Thankyou also to NQ Dry Tropics staff and associated contractors for managing and delivering the rehabilitation projects,to Peter Zund(QDES)and Seonaid Philip(CSIRO)for their support obtaining soil descriptions and samples,and to Shawn Darr and the Queensland Government for access to the gully density mapping data(Fig.1).We would also like to thank the property owners for allowing access to their properties and involvement in the projects-Darren Watts and Family,Warren Woodhouse and Christian and Melissa Cormack.We thank the editor and reviewers for review comments which have significantly improved this paper.
文摘Millions of dollars are being spent on gully rehabilitation to help reduce excess fine sediment delivery to the Great Barrier Reef(GBR).There is an urgent need for(i)prioritisation of active gullies for rehabilitation and(ii)the development of methodologies to inform the effectiveness of remediation.In this study we analyse DEMs of Difference derived from 0.5 m resolution 2-3 year interval multi-temporal LiDAR data collected pre and post rehabilitation at three variable gully morphologies in the Burdekin catchment.Our analysis indicates that the highest annual average fine sediment erosion rates for the untreated control gullies occur at the linear gully(53.38 t ha^(-1)y^(-1))followed by linear-alluvial gully(34.24 t ha^(-1)y^(-1))and least at the alluvial gully(14.41 t ha^(-1)y^(-1)).The proportional loss or export of fine sediment from the gullies in their un-treated condition ranges from∼68 to 90%of what is eroded,and when the gullies are treated the proportion of fine sediment that is retained in the gully proportional to what is eroded increases to∼60%at all sites.Without pre-treatment baseline erosion rates,and additional post treatment LiDAR captures,it is difficult to quantify the treatment effectiveness.Our results offer insights in the erosion mechanisms within different geomorphic gully morphologies and rehabilitation effects in these erosional landforms.This study provides crucial knowledge of gully dynamics that can be coupled with other lines of evidence for better prioritisation of rehabilitation in the GBR catchments.
文摘Daley et al.(2023a)argue that at least 10-15 years apart Digital Elevation Model(DEM)derived DEMs of Difference(DoD)surveys are needed to detect reliable geomorphic change within the gullied landscapes of the Great Barrier Reef,Australia.We acknowledge that the reliability of observed geomorphic change increases as more subtle geomorphic processes are detected with longer monitoring periods.As further good quality long-term legacy datasets become available,we encourage utilising these to improve confidence in targeting erosion rehabilitation.However,our approach to consistently apply 2-3 year DoDs to contrasting gully morphologies enabled capture of more intense geomorphic processes acting over shorter timeframes and provided valuable and timely information on(i)contrasting erosional mechanisms and erosion rates between variable gully morphologies,and(ii)rehabilitation efforts un-dertaken.In this paper,we take the opportunity to concisely address all the concerns raised by Daley et al.(2023a).
