QGC Pty Ltd carried out an Environment Impact Assessment (EIA) in Queensland, Australia with the help of the 2D FAST solver within Flood Modeller Pro. The study area was 1,200 square kilometers and as part of the project, it was necessary to analyse the potential flood risk for the entire area.
As there had not been previous hydraulic or hydrological models built for the study area and only one downstream gauge existed, there was very little data available to support traditional hydraulic modelling.
It was originally intended to attempt simple calculations based on the Manning equation for selected cross sections. However, due to the large size of the study area, it was extremely difficult to define where the calculations should be applied.
It was therefore decided to undertake simulations using the 2D FAST solver within Flood Modeller Pro to generate a rapid assessment of flood risk for the full study area to better understand the flood risk.
A digital terrain model (DTM) was being developed from the 1m contour lines and this provided an appropriate scale DTM for the broad scale 2D FAST modelling.
The core functionality of the 2D FAST solver is to spread flood water over a DTM using a simplified representation of the physical processes.
Its high computational efficiency, robustness (numerical stability), and volume conservative approach (which focuses on identifying ponded areas) made it suitable to identify risk of flooding (at the broad scale) in this area of Queensland.
Overall, the 2D FAST solver was extremely simple to use, fast and provided better than originally expected results.
Sensitivity tests were run to better understand the results and to help ensure that the confidence in the outputs could be communicated to end users.