Nodes

Inflow

Defines the flow (including constituents and ownership) entering the network as a result of tributary inflows, inter-basin transfers, discharge of groundwater systems and outflows of infrastructure such as sewerage treatment plants.

Gauge / Unaccounted Difference

Used where there is measured flow (and/or constituent) data at some point in the river network, OR where modelled outputs are required for reporting. Gauges node can be used as comparison points, or the observed flow can be used to override the upstream modelled data for downstream. When overriding the modelled flow with observed, the gauge icon changes and the node reports the ‘unaccounted difference’ between the observed and predicted data.

Confluence

Represent joins in a river system, where two upstream flows are joined into one downstream flow without loss or delay. The bulk of the configuration of a confluence is in terms of influencing the passage of orders from downstream to storages upstream of the confluence. Confluences can be unregulated, where neither upstream branch contain any storages, or they can have regulating structures upstream on one or both of the branches.

Loss

Describe the amount of water that is lost from the stream network at a point. Loss relationships can represent physical processes, such as transmission losses, or they may be used to represent measurement error in the input data for the model.

Maximum Order Constraint

Used at points in the network where a physical or management constraint exists to prevent regulated flows exceeding a certain threshold. These thresholds can be expressed as a constant (typically to represent a physical constraint, such as a choke point) or as a variable constraint using an expression (typical for management constraints). Where the orders originating downstream of the constraint are above the current threshold, the orders are reduced.

Minimum Flow Requirement

Used to maintain a specified minimum flow at a point in the network. Where the orders originating downstream of the Minimum Flow Node are less than the minimum, additional orders are placed in order to meet the threshold. Minimum flows can be specified as a monthly pattern, a time series, or an expression.

Off Allocation

Used to determine how much off-allocation flow is available in the river (at the node), as well as how to share this between the downstream water users that have licence shares. Off-allocation flows are those that are in excess of regulated requirements.

Parallel Arcs

Used to specify costs on a particular supply path, in order to influence the distribution decisions in NetLP mode.

Splitter

Used where the network divides into two, such as major anabranches. Splitters can represent control structures, in which case the water going down each of the links is a management decision, or uncontrolled branches, where the water going down each links is a function of upstream flow alone.

Storage

Used to hold water at a point in the network. Storage Nodes are used for various types of water bodies, including major reservoirs (on river and off river), weir pools and urban lakes. Storage Nodes can capture much of the operating details of regulating water bodies, such as release structures and operating rules, as well as physical properties such as surface area relationships for evaporation, rainfall and groundwater.

Supply Point

Are points in the stream network where water demands are represented for the purposes of either extraction (for consumptive use) or for in-stream use. Supply Points are coupled to a single Water User Node, which calculates the actual demand, noting that a single Water User Node can make use of multiple Supply Point Nodes in order to place demands in multiple parts of the system.

Transfer Ownership

Used to reassign the ownership of water instream at a point in the network, such as reassigning an owners water when the water flows past the last opportunity that the original owner had to extract the water.

Water User

Represents the actual demands (consumptive or non-consumptive) in the system. Water Users can model demands by way of several alternate demand models, and then seek to have these demands met either by localised storage, or from one or more Supply Points. The demands can be distributed between these sources, either by a set of user specified rules, or by way of a Resource Assessment System.