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title: "Flow Rate Calculations for Restriction Planning"
canonical: "https://docs.rubiconwater.com/space/PNC/2051867272/Flow%20Rate%20Calculations%20for%20Restriction%20Planning"
format: markdown
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> Macro (toc)

# How are Flow Rates for Orders Calculated?

Flow rates for orders affected by a restriction are based on the share allocated to the affected properties.

> ℹ️ **Note**
> ℹ️ 
> ℹ️ The share of the flow allocated to each property is set in an attribute. You can specify which attribute you want to use to store this share value, but the default attribute is the *Flow share*. See <u>[Configuring the Restriction Planning Tool](https://rubiconwater.atlassian.net/wiki/spaces/PNC/pages/2051899964)</u> for more details.

When a flow restriction is applied at a regulator, the following calculations are made for affected orders downstream:

1. The proportion of the total flow available for each property is calculated from the property flow share attribute.
2. If the orders for a property do not exceed its share of the available flow, the order is unchanged and the property receives the flow that it ordered. Any additional flow that the property is entitled to, but does not need, is added to the flow available to other properties.
3. The calculation is repeated, excluding the properties that do not exceed their flow entitlement until the allocated flow for each property has been calculated.
4. If a property has orders for more than one outlet, the flow allocation for that property is delivered to those outlets in proportion to the original requested flow rate.

## Example Calculation

Suppose we have four properties A, B, C and D with orders supplied from a regulator. A, B and C have a flow share of 1, and D has a flow share of 2. The orders require a total of 110 ML/d, but we will restrict the regulator flow to *90 ML/d*.

**Step 1**

Calculate the maximum flow that each property would be allowed based on their flow share:

|  | **A** | **B** | **C** | **D** |
| --- | --- | --- | --- | --- |
| Flow Share | 1 | 1 | 1 | 2 |
| Percentage of total flow share | 20% | 20% | 20% | 40% |
| Ordered ML/day | 10 | 25 | 35 | 40 |
| Maximum share of 90 ML/day | 18 | 18 | 18 | 36 |

In this case, property A has ordered less than its maximum share, so we deliver the ordered 10 ML/d to A. The flow remaining is now *80 ML/d*.

**Step 2**

Ignore any Properties that have ordered less than or equal to their share of the available flow and repeat the calculation for the remaining orders to distribute the 80 ML remaining:

|  | <span style="color: #97a0af">**A**</span> | **B** | **C** | **D** |
| --- | --- | --- | --- | --- |
| Flow Share |  | 1 | 1 | 2 |
| Percentage of total flow share |  | 25% | 25% | 50% |
| Ordered ML/day |  | 25 | 35 | 40 |
| Maximum share of 80 ML/day |  | 20 | 20 | 40 |

In this case, the flow remaining is sufficient to supply the full order for D. We deliver 40 ML/d to D. The flow remaining is now *40 ML/d*.

**Step 3**

Ignore any properties that have ordered less than or equal to their share of the available flow and repeat the calculation for the remaining orders to distribute the final 40 ML:

|  | <span style="color: #97a0af">**A**</span> | **B** | **C** | <span style="color: #97a0af">**D**</span> |
| --- | --- | --- | --- | --- |
| Flow Share |  | 1 | 1 |  |
| Percentage of total flow share |  | 50% | 50% |  |
| Ordered ML/day |  | 25 | 35 |  |
| Maximum share of 40 ML/day |  | 20 | 20 |  |

Both B and C have ordered more than their maximum restricted flow, so we deliver each property its maximum share of the available flow. The calculation is now complete and the final flow allocations for the restriction period are:

|  | **A** | **B** | **C** | **D** |
| --- | --- | --- | --- | --- |
| Ordered ML/day | 10 | 25 | 35 | 40 |
| Received ML/day | 10 | 20 | 20 | 40 |

# Flow Restriction Intervals - Refining the Flow Restriction

A flow restriction may be divided into intervals and the calculations are repeated for each interval. This allows for the possibility that the order balance may vary during the period of the flow restriction so the optimal flow share may change.

# Flow Rate Precision

When restriction rates are calculated, the new flow rate may be rounded down. The precision of the restricted flow rate is determined by the **Restriction Flow Rate Rounding** parameter. For example, if the parameter value is 0.5, the restricted flow rate will be rounded down to the nearest 0.5.

See <u>[Configuring the Restriction Planning Tool](https://rubiconwater.atlassian.net/wiki/spaces/PNC/pages/2051899964)</u> for more details.

# Dealing with Restricted Flow Fates of Zero

The calculated restricted flow rate for some orders may be zero. This may happen because of rounding during the calculation, or if the Flow Share attribute for the property is not set. In this case, any non-zero flows for the order are split into separate orders. A new, cancelled order is created for the part of the order with zero flow.

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