A Supply Point node (Figure 1) represents a location in the river where water can be extracted to meet demands. You can specify whether water is to be taken from regulated water, unregulated water or groundwater sources.
Figure 1. Supply Point node
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| Note: Only one of the effluents from a supply point node must connect to a water user node. |
Supply point configuration
Enabling Extract water checkbox will ensure that the supply point extracts water. If disabled, water will not be given to the water user, and it will be passed downstream. This is the only difference between enabling and disabling the checkbox. Disable the Extract Water checkbox for demand models which require a flow at the supply point, but require the flow to remain in-stream, ie., the order will not actually be extracted. This could be used for shepherding environmental releases, for example.
The Groundwater checkbox signifies the supply point as a groundwater . In case of the Namoi model, when enabled, this type of account has the least priority for obtaining water. It must pump. It will be used only when there is crop demand and there is no available regulated and , supplementary water, and or water from on farm storage to satisfy crop demand. Note that this groundwater account must not prevent off allocation diversion. You must set the maximum extraction rate (ML/day) for groundwater sources.
Enabling the Allow Orders checkbox essentially means that the supply of water to the water user is regulated. This will affect water distribution if account sharing has been set up in the Water user node. Refer to Account sharing (full Source version only);
Add Orders to Downstream Orders
This option only applies to non-extractive use supply points and is available when Extract Water is unchecked AND I Allow Orders is is checked. (It The supply point behaviour becomes similar to a minimum flow node)If a the water user attached to the supply point is 'requiring' requires water, the water user requirement volume is added to the downstream orders.e.g Downstream of the supply point there is currently a 20ML order downstream, the water user requires 30ML, the supply point will order 30ML and the total ordered volume upstream will be 50ML. When When this option is unchecked it will only add to the order , if the water user requirement is greater than the difference between the downstream order , and it will only order the difference.e.g Downstream of the supply point there is currently a 20ML order downstream, the water user requires 30ML, the supply point will order 10ML and the total ordered volume will be 30MLwater user requirement.Use Unregulated Flow to Satisfy Orders
When this option is checked the forecast unregulated water is considered to be available and the supply point will only order the difference.
Specifying an Over Order Factor will allow you to choose apercentage factor representing additional water released to meet a particular order, eg a factor of 1.2 or 120% means that the demand is scaled up by 20% in the ordering phase. The additional water is sourced from the upstream storage
Units: Percentage or proportion
Allowable range: Positive integer (%) greater than or equal to 100. Values of less than 100 (%) or 1 (proportion) are changed back to 100% or 1.
Default value: 100%
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| Note: Accounts are not debited for the additional water ordered as a result of the over order factor. |
During the flow phase, the extraction actually available to the water user is the minimum of i) the original order (not including the over order factor), or ii) the physical extraction capacity, or iii) any river flow constraints.
The over order factor does not necessarily need to incorporate all estimated delivery losses in the system. If there are upstream nodes or links which simulate losses in the system between the storage and the supply point, Source automatically increases the order to account for estimates of those losses. Refer to the individual node descriptions in the Source Scientific Reference Guide for methods used to estimate losses.
The over order factor is used to add further contingency to a storage release. It should therefore only be calibrated after the physical characteristics of the system have been completely configured. It is up to you to select (or calibrate) an over order factor which is realistic for the system (to ensure that unnecessary water is not released from the storage).
Maximum Extraction Rate
The maximum extraction rate is the highest possible pumping rate for in bank flows. It can be specified using a value, data source, function or rate table. Optionally you can add an additional pump capacity for overbank flows by specifying an ovebank threshold and overbank pump capacity.
If you are extracting surface water, specifying a maximum extraction rate is optional, as the extraction will be limited by other factors such as orders and flow in the river. If groundwater extraction is selected, a maximum extraction rate must be provided otherwise unlimited amounts of water will be available.
The absence of a limit on supply point pumping capacity can lead to a situation where the Maximum Extraction Rate result cannot be displayed because it will contain infinite values resulting in an empty graph.
Overbank Threshold
The overbank threshold should be configured if you want to simulate floodplain harvesting by the water user. Overbank flow occurs if the flow rate in the river rises above the specified overbank threshold. Any overbank water can be used to meet the demand model or water user storage requirements without incurring a debit on the water user’s accounts.
Overbank Pump Capacity
The overbank pump capacity is the additional pump capacity that can be used to pump flows in excess of the overbank threshold. It can be specified using a value or function.
Diversion Threshold
The supply point will not be able to pump any water below the diversion threshold. It tries to mimic the fact that the pump may not be at the very bottom of the river. Therefore, you need a certain volume of water in the river before you can pump any at all. It affects the system during the flow phase of the supply point only. It can be specified using a value or function.
Specify maximum account deduction (full Source version only)
If Extract water is not enabled, you can specify maximum account deduction which will limit water debited to an accounting system; if this deduction cap is more than total order water, the total order water is debited. This parameter can be specified as a value or a function.