17.5 Overbank flood spilling
The volume of overbank flow from the river channel during the 2011–12 year cannot be quantified accurately due to a lack of available data; however, even during periods of major flooding, this volume is likely to be relatively small. Most streams in the upper reaches of the Ord region above Lake Argyle flow in confined channels. In the regulated lower Ord River, the volume of overbank flow inundating the floodplains has decreased significantly since dam construction. Therefore, the omission of this volume in the water account does not have a material impact on the water balance of the surface water store.