Modifying the River Lines Toolkit for the mapping of the NSW river network
The Challenge
Water (hydrology) is one of the ten NSW Foundation Spatial Data Framework (FSDF) themes, and ‘Hydro Line’ is the dataset that defines the centreline of water courses. The NSW Department of Finance, Services and Innovation (DFSI) Spatial Services continuously updates the Water theme with information sourced from stakeholders and custodians. As NSW has approximately 58,000km of rivers and major streams, this is an arduous task and the accuracy of the data is currently poor. Of relevance is the FrontierSI developed River Lines Toolkit (RLT), which was used for mapping the Victorian river network and has been integrated into the Vicmap products. RLT is a largely automated approach for the consistent and accurate mapping of river streambed and bankfull lines from elevation data over large river networks. The aim of this project is to customise and enhance the RLT to improve the mapping of the NSW Water theme, including Hydro Lines.
Partners
The primary project partner was NSW Department of Finance, Services and Innovation (DFSI) Spatial Services with Spatial Vision providing training and support to DFSI Spatial Services to run the River Lines Toolkit. The NSW Department of Industry – Water Branch (DoI) and the NSW Department of Planning and Environment – Office of Environment and Heritage division (OEH) were also key stakeholders.
The Solution
A pilot study was conducted using RLT to produce streambed, bankfull and centreline delineations for three pilot catchments within the NSW river network. The three catchments provided varied landforms and data types (1m, 2m and 5m DEMs) which were used to determine the effectiveness of RLT to delineate rivers across NSW. The outcomes of the pilot study informed a detailed project plan for the upgrade of the NSW hydro theme.
The next activity involves modifying RLT so that is can ingest the NSW standard LiDAR and aerial imagery data formats, as the software was originally designed to work with Victorian data structures and formats. This activity is being run using agile software development which involves frequent communication with DFSI, delivering components for testing often and responding to feedback. Early on in this activity a decision point was reached to either adjust the existing code or re-write it. The decision was made to re-write the code for several reasons including:
- To employ a new virtual raster technique (VRT) to remove the tiling method of processing data which caused errors
- To implement a modular structure to easily enable components to be delivered and tested with feedback provided throughout the development. It includes the following modules;
- VRT
- Seedline
- Control points
- Detrend
- Streambed
- Bankfull
- Centreline
- Quality assurance
- To focus on improving the automated tools and reduce the need for the manual improvement tools
Once RLT has been upgraded, FrontierSI will work closely with partner Spatial Vision who will provide training and support to DFSI Spatial Services to run the RLT to map the NSW river network.
Impact
There are many users of FSDF hydrology data. Key users include State, Local and Federal Government agencies who use the data to better manage assets. More widespread use of hydrology data is also found in emergency management response and recovery efforts, hazard mitigation or disaster risk reduction, climate change, natural resource assessment, environmental planning and monitoring, insurance, mining and agriculture.
DOI and OEH require a consistent, accurate and timely delineation of the NSW Hydro Line network for legislation and regulation enforcement. The NSW Water theme no longer meets the needs of users and requirements within current NSW legislation. Errors in the current river position can be more than 300m in places, with numerous rivers misaligned to base datasets (e.g. topography and imagery). The RLT provides a unique opportunity for the NSW Government as it was purpose built to delineate streambed, bankfull and centrelines over large river networks. Currently, there are no other tools that can continuously derive all these features over large river networks. The upgraded RLT will provide an automated approach for the consistent and accurate mapping of river streambed and bankfull lines from elevation data across NSW river networks.
Contact
To learn more, contact FrontierSI at contact@frontiersi.com.au .
