Every Flow-MER theme relies on high-quality inundation maps and data for their evaluations. Each year as part of their service of providing hydrology data, the Basin-scale Project team maps the streams and wetlands in the Basin where Commonwealth environmental water was delivered and likely contributed to inundation. With data coming from the Commonwealth Environmental Water Holder (CEWH), 4 states, 7 Selected Areas (increasing to 10 under Flow-MER2.0) and publicly available satellite imagery, this is no mean feat!
Every year, the CEWH compiles data on how much Commonwealth environmental water it delivered, as well as where, when and why. The Basin-scale Hydrology team translates the CEWH data into maps of streams and wetlands. The team also uses streamflow data from around 140 stream gauges to follow pulses of environmental water as they move through the Basin. The streamflow data are used to calculate how much of the water is Commonwealth environmental water and as an important cross-check that the water’s going where it’s intended. Adding rainfall data and modelled runoff further paints the picture of how much water is moving through the Basin.
The inundation products must also pass the ‘pub test’ – so the draft maps and data are checked by the water delivery teams, site managers and Selected Areas to make sure they match up with the reality on the ground. A final, painstaking check of all the maps and data by the Basin-scale team completes the process. These inundation products are now being used by the theme teams for their 2023–24 evaluations.
