When combined with the Einasleigh River, the Gilbert River has the sixth-highest discharge of any river in Australia, slightly less than that of the Potomac in North America. In an intense wet season, however, the discharge can be as large as that of the Fraser River in Canada, and in a mild wet season like that of 1951-52, the discharge can be as little as one tenth of the long term mean.
When combined with the Einasleigh River, the Gilbert River has the sixth-highest flow rate of any river in Australia, slightly less than that of the Potomac in North America. In an intense wet period, however, the flow can be as large as that of the Fraser River in Canada, and in a mild wet period like 1951-52, the flow can be as little as one tenth of the long-term average.