Water Balance Tool

The Hydrometric Network and Remote Sensing (HNRS) program was established by the Murray-Darling Basin Authority (MDBA) to increase the amount and quality of publicly available information about water in NSW. A HNRS workstream produced a water balance tool that provides up-to-date information on water gains and losses at a reach and catchment scale.

Water balance is a common approach in hydrology based on mass balance principles. This means that the sum of inflows, outflows and changes in water stored must balance over a given time step.

The visualisation tool is populated with observed and modelled outputs and is updated daily. The water balance tool has been rolled out to the Namoi regulated river. Roll out to additional river systems is planned subject to funding and resource availability.

• The data on the visualisation is updated daily. Data gaps are filled using estimates and/or previous forecasts.
• There is uncertainty regarding the high flow readings above the channel capacity.
• The reach entitlement volume displayed on charts and tables represents the maximum potential entitlement volume in the reach. The entitlement held on an access licence is available for extraction via all linked work approvals, which can be located across multiple reaches. The volume extracted via a work approval will vary each year depending on climate, seasons, allocation and cropping patterns.
• Reach 13 (Goangra (419026) to Walgett (419091)) downstream gauge only provides level information and no discharge.  Reach 15 (Downstream Pian Cutting (419079) to Hazeldene) does not have a measured downstream gauge to compare against the modelled flows. Therefore, both reaches have been excluded in the water balance tool.
• The extraction volume is showing the licenced extraction from the reach and may include environmental water that is not extracted. Until more information is available on how Held Environmental Water is to be used, it has been modelled as a consumptive use.
• Data sourced from external database may be revised and/or corrected over time.
• For some reaches, it is not possible to develop reliable estimates or calculation of the water balance component volume e.g. losses, ungauged inflows. When this situation occurs, the volume of the component contributes to the unaccounted difference in reach.
• A comprehensive analysis on water availability, allocations, usage, trade and delivery is provided in the Department's annual General Purpose Water Accounting Report for the NSW regulated water sources.