Condamine Balonne

The Condamine-Balonne catchment represents a vital part of Australia's water resources. It is located in the upper reaches of the Murray-Darling system, to which it forms an important catchment area. The sustainable management of water in the system is crucial to Australia's future.

This project examines two technologies that aim to assist in the management of water resources:

• Estimation of flood extent, and the volume of flood water; and
• Continuous flow forecasting.

Activity 1: Flood extents & water volume

The aim of this activity is to use satellite imagery to identify surface water, such as a flood, in a target area. The surface water is then combined with a digital elevation model (DEM) to provide an estimate of the volume of water in the event.

The first step is to process the reflectance data from the MODIS satellites to estimate where the water is in the image. A percentage, representing the proportion of surface water area, is allocated to each image pixel in the target area.

The next step is to overlay the water "surface" onto the DEM to identify the lowest areas (MODIS data coverage is approximately 500M and the DEM is 30M). This step provides an estimate of how much water is in each MODIS pixel. These amounts are then summed to provide the volume of water.

The DEM was derived from the Shuttle Radar Topography Mission and provides 1 second (approx. 30M) elevation data for the whole of Australia.

	MODIS image of Southern Queensland, the Condamine-Balonne area is highlighted. The MODIS reflectance data is used to identify water within each image pixel. There are two MODIS satellites, called Aqua and Terra.
	The Digital Elevation Model of the land around the town of Condamine, QLD. The Condamine River flows diagonally across the area top-right to bottom-left.
	A prototype Google-map application showing the estimated water for June 4th, 2009. The pseudo-colour indicates the amount of water per pixel as a percentage. The town of St. George, QLD, is at the top-right and the flood-plain is the area going diagonally to the bottom-left of the image.

Activity 2: Continuous flow forecasting

Modeling of river flows is usually performed on an ad-hoc based. This activity aims to implement a system that runs the forecasting models continuously using live data feeds for rainfall and gauge data.

The modeling workflow will be managed by a system called Flood Early Warning System (FEWS) that has been developed in the Netherlands. FEWS workflows will manage the execution of the models and the flow of data between them.

One of the biggest challenges in continuous forecasting is the management of the uncertainty: when models are chained together and the output of one forms the input of the next in the chain then data errors begin to multiply. The project will apply state of the art assimilation techniques to reduce this uncertainty along with advanced visualization schemes to facilitate its interpretation by the user.

Due to tight operational time constraints, particular efforts will be put on minimizing the models' calculation time. Several combinations will be tested to find the optimal balance between model performance and fast execution.

A screen shot of the FEWS main screen. This screen shot shows the catchment area and some of the monitoring stations along the Condamine and Balonne rivers. The flood plain below St. George is the light-green at the bottom of the map.

See also

• Condamine-Balonne region: CSIRO Murray-Darling Basin Sustainable Yields Project
• Murray Darling-Basin Sustainable Yields Project
• Condamine Balonne catchment - Queensland Department of Environment and Resource Management