Many regional councils throughout New Zealand monitor rivers to record changes in the riverbed topography either through natural sedimentation and erosion or through the impact of gravel extraction operations. They then review the build-up and loss of gravels in the monitored rivers.
e2Environmental was engaged by Tasman District Council and the greater Wellington Regional Council to assess river gravels in monitored rivers and to provide a gravel status report to help inform ongoing river management decisions.
A combination of aerial imagery, new and historical cross-section surveys, LiDAR, and drone digital surface modelling were used to derive new active channel widths and mean bed levels for each river’s cross-section. Reviews of historical data were conducted to confirm the accuracy of previously calculated values by others.
Data was analysed to determine trends in gravel behaviour and in the riverbed by contrasting historical surveys with the most recent survey and accounting for extracted gravels.
e2Environmental assessed how these trends impact future conditions in the river and recommended options for future gravel management including gravel extraction aligned with river management requirements.
Project manager(s)
Harry Petterson
Services involved:
