14 July 2022
In Australia, the impact of flooding from both tropical cyclones (e.g. TC Debbie, 2017) and extratropical storms (e.g. along the East Coast in 2010/2011 and 2022) have shown the vulnerability of low-lying areas in floodplains and along the coast to flooding. Particularly when flooding from rainfall, rivers, and the sea converge, it can cause significant damage to infrastructure and even loss of life. A national Flood Inundation Intelligence System (FliFS), currently in the Proof of Concept (PoC) phase, has been developed to help reduce these impacts in Australia.
Figure 1. Forecasted maximum inundation extent and water depth in Brisbane, simulated by FliFS in February 2022 with pictures for on- site verification.
The FliFS PoC was financed directly by the Australian Climate Service (ACS) - tasked with providing data and intelligence to improve national response to climate and natural disasters. The ACS consists of expertise from the Bureau of Meteorology, Australian Bureau of Statistics, Geoscience Australia and CSIRO. The project team consisted of Deltares, with Australian sub-contractors Water Technology and Worley (waterRIDE).
The FliFS PoC leveraged the Bureau of Meteorology’s (Bureau) system, which uses rainfall and streamflow observations, numerical weather predictions, and hydrologic models to forecast and warn for possible flood events across Australia. The technical core of the underlying Bureau hydrological forecasting system (HyFS) uses Delft-FEWS as its operational framework. The purpose of the current FliFS PoC is to investigate the feasibility of extending the existing system with additional hydrological, hydrodynamical flood inundation, and flood map interpolation models. The goal is to provide end users with flood inundation forecasts, real-time inundation analysis, and post-event flood maps to support decision-making before, during, and after events.
FliFS PoC disseminates several products through multiple pathways. One product, which proved most useful to end users during the PoC, is the maximum flood extent provided as a polygon shapefile. FliFS PoC generates forecasts twice a day, including the maximum flood extent for all models along the coast (NSW, QLD, and NT). When the Bureau issues a forecast for the rivers in one of the 6 waterRIDE models, this triggers FliFS PoC to produce a maximum flood extent for the relevant models as well. Flood extent shapefiles are uploaded automatically to ArcGIS Online, from where they can easily be integrated by end users in their existing ArcGIS workflows.
The FliFS PoC is hosted in a Azure cloud and consists of a modelling framework, Delft-FEWS operational system based on HyFS, and dissemination and archiving of data via a Delft-FEWS webservice, Delft-FEWS Open Archive, and ArcGIS Online (Figure 5).
Figure 2. The four components of the FliFS PoC.
The modelling framework uses a tiered approach to providing spatial flood data:
• Statewide flood inundation models covering the coastal zone, including all major cities (SFINCS, Figure 4), with input from runoff forecasts derived from statewide gridded hydrological models (Wflow, Figure 3)• Settlement-wide flood inundation models for 6 different regions (waterRIDE), using official bureau forecasts included in warnings as inputs
Figure 3. Wflow model domains and forecast locations for the Australian East Coast with an example hydrograph at one output location (from the validation study).
Figure 4. The thirteen SFINCS model domains available in FliFS PoC, together with inundation results as computed in SFINCS for the Brisbane 2011 flood (in red) compared to the observed inundation (in blue).
Figure 5. Shapefile depicting maximum forecasted flood extent from FLiFS loaded into the ArcGIS Online environment.
During the extensive floods in February 2022, the PoC demonstrated that a flood intelligence software solution can be built that is scalable, interoperable, fit-for-purpose, and adaptable to the real-world challenges of emergency management. It showcases the technologies to be used in development, and how the software solution can be adopted and applied by its intended users. The products of the system can easily and freely be shared with others and the method of creating those products is completely transparent.
New gridded hydrological (Wflow) and inundation models (SFINCS) were developed in a very short time to cover large parts of Australia (using HydroMT). It’s the first Delft-FEWS system that integrates the waterRIDE hydraulic interpolation algorithm. It is also the first time Delft-FEWS has been used to convert inundation time series to polygons, export them as shapefiles with metadata and attribute tables, and automatically load them into ArcGIS Online.
More work is required to develop this PoC into a fully-operational system for decision-making during flood events in Australia. Such developments may include:
• Pilot on accuracy - to refine and validate flood models• Pilot on usability - to further integrate Delft-FEWS with online GIS environments• Pilot on robustness - to manage the large amount of (gridded) data• Pilot on coverage – to expand the spatial coverage to other states and eventually Australia
Simone De Kleermaeker
Sr. Researcher / consultant