The Flood Modeller 2D FAST solver has been used as an environmental water management tool for Yanga National Park, a large River Red Gum forest on the Murrumbidgee River in New South Wales, Australia.
The Park receives water from both natural overbank flood events and controlled inflows through river bank structures. Park managers need to know the inundation extent such events will produce, to help in planning short-term park operations, and in the longer term to predict the frequency at which each part of the Park receives water. Estimating the future frequency and duration of flooding is of great interest, because it strongly affects the health and type of ecosystems that the Park can support.
As the Park covers approximately 76,000 hectares a traditional fully hydrodynamic two-dimensional model runs too slowly to be used for water management scenario modelling, unless a large grid scale representation of the floodplain is adopted.
However the simplified hydraulics of our 2D FAST solver allowed a very detailed grid to be used, with simulations covering several months typically taking only 3-4 hours. This potentially makes it realistic to simulate a wide range of different water management options.
The model was constructed as a linked 1D-2D model. It uses a traditional one-dimensional representation of the Murrumbidgee River, linked by weir type overflow boundaries to the FAST floodplain model. Developing the entire model, including the 1D river channel component, took approximately 2-3 weeks.
This inundation event was produced by overbank flooding following several months of heavy rainfall in the Murrumbidgee in late 2010. The Murrumbidgee River channel is the black line along the upper margin of the image.
Li Wen, New South Wales Government commented: "We've simulated two events and the 2D FAST solver inundation outlines are close to outlines we obtained with a full HD 2D model covering the same area. The run time for the larger of the two events was approximately 2% of that of the full HD model".