Introduction
There are two three key components of rules-based ordering:
- Calculation of order time within a network - order time is calculated in the initialisation phase of a Source project and is required by the ordering and off-allocation systems to determine how many time-steps into the future water orders need to be processed for at each network component; and
- The way orders in the network are processed at each node/model component - Orders are processed in the constraint and order phases. During the ordering phase, water orders and off-allocation requests are accumulated from downstream to upstream and consider the average travel time of water in the regulated river system downstream of a reservoir.
- Prioritisation of orders from nodes to determine which orders will be met first in the system in the event of any shortfall
Rules-based ordering at nodes and links
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Routed links may gain or lose water due to rainfall, evaporation and groundwater (seepage) as flow does not travel from one end to another instantaneously. You can choose which of these lateral fluxes the ordering system takes into account by enabling the relevant checkbox shown in the node’s feature editor (Figure 1). The data for each of the fluxes is taken from its corresponding item in the hierarchical list. For example, if you enable Use Loss/Gain, Source uses the table specified in Loss/Gain. If you choose Groundwater as one of the fluxes, you must specify a time series for it, which can be imported.
The order coming into the routed link is adjusted to cater for the lateral fluxes over each time-step that the ordered flow spends in the link.
Figure 1. Link (Ordering)
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| Note: Changes in link storage volume are not forecasted over the order period, as it does in the storage node. So, where there are significant jumps in the volume ordered, there may be insufficient water stored in the link to achieve the required downstream flow to meet orders. |