Loss node - SRG

The loss node describes the amount of water that is lost from a point in the stream network. Losses may include physical processes such as transmission losses due to evaporation and seepage, or may be used to represent losses associated with measurement error in the data used to develop the model, such as flow-measurement uncertainty.

Scale

Losses are implemented at the site-scale.

Principal developer

eWater

Scientific provenance

Introduced in RiverManager.

Version

Source version 4.3

Dependencies

The loss node must be part of a node link network.

Availability

Loss is automatically installed with Source.

Structure and processes

A loss is specified relative to the flow at that point in the system using a monotonically increasing piecewise linear function.

Basic Function

The basic function of a loss node is to remove water from the river network

Order Phase

The Loss node affects the order phase of a simulation if the Loss node is downstream of a storage. Orders being passed up to the storage will be increased by the forecast loss. Orders isare covered in more detail in https://wiki.ewater.org.au/display/SD411/Ordering+-+SRG

If ownership is enabled, the loss is shared between owners based on either by proportion or by a user defined fixed ratio. When the fixed ratio sharing method is selected it is also possible to define a High Flow Threshold. Above the High Flow Threshold, Losses are split according the fix ratio specified below the High Flow Threshold, then in the ratio of the ownership of the water above this threshold. Ownership it covered in more detail in the https://wiki.ewater.org.au/display/SD411/Ownership+-+SRG

Ownership off

When there is no ownership in the system, the loss node increases the current order by the forecast loss.

Ownership On

The share in the losses is forecast based on the user specified method.

When the sharing method selected is “Proportional” losses are added to each owner’s orders in the proportion to the downstream orders.

When “Fixed Ratio” with no High Flow Threshold is selected losses are added to each owner in the fixed ratios specified.

When “Fixed Ratio” with High Flow Threshold is selected, the high flow threshold should be set to the top of the regulated range. Therefore, orders should never exceed this threshold. When orders do not exceed the High Flow Threshold, loss up to the High Flow Threshold are split according to the fixed ratio. This is the same as Murray Style High Flow Losses on Links see: Ownership in Links - SRG

Flow Phase

During the flow phase the total flow downstream of the loss node is reduced based on the value determined from relationship between inflow and loss at that point in the network.

Ownership off

When ownership is off water is removed from the system based on the defined relationship between inflow and loss.

Ownership on

When ownership is on losses are shared based on the user defined method.

When the sharing method selected is “Proportional” losses are split based on the proportion of the water owned by each owner.

When “Fixed Ratio” with no High Flow Threshold is selected losses split based on the fixed ratio specified by the user.

When “Fixed Ratio” with High Flow Threshold is selected losses are spilt based on the fixed ration until to the High Flow Threshold. Above the high flow threshold (or regulated range) the loss is shared to the owners in proportion to how far each is above their fixed share of the regulated flow range. This is described as “Murray-style high flow losses” in the Ownership in Link SRG (Ownership in Links - SRG)

Input data

The input data for the Loss model is a relationship between inflow and loss from a point in the network. The data entered into the table or configured in a .csv file must be in increasing order and the increase in loss must be less then the increase in inflow. Seasonal variation can be specified using a monthly pattern table, and you can choose to interpolate or step change (default).

Parameters or settings

Model parameters are summarised in Table 1.

Table 1. File format for a piecewise linear function configured as a .CSV file

Output data

The loss node outputs a time series of flow.