Introducing demand

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When using info works.

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WS pro it is important that you understand how

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this software accounts for the demand on water networks

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demand,

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which can vary over time is the water that is

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required by users at a given point within the network.

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For example,

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the water required by a housing development would be

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different from that of a school or factory.

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Water transfers can be considered a positive or negative demand on

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the network depending on if the water is entering the network,

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negative demand or leaving it positive demand.

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In reality,

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a network will also experience some degree of leakage which is any water

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lost from a point in the network that cannot otherwise be accounted for.

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This leakage can be represented in info works. WS pro

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water companies tend to have three general categories of water

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revenue,

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non revenue

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and other

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revenue.

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Water is defined as metered or un metered consumption that is paid for by the user,

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non

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revenue. Water nrw

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can be unauthorized use or losses due to leakage or main breaks.

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Other is defined as exceptional demand or transfers.

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The general principles of allocating demand in a network can vary

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but a typical process involves first identifying the

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various types of customers in the network.

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Then

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the 24 hour flow profile or daily usage

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pattern is used to determine how to allocate water

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to do this. You must identify leakage using the minimum nightly flow.

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With the assumption that the water leaving the system at this time

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is being lost to leakage rather than consumed by a user.

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Then you subtract any known legitimate use flows from

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the remaining flow to find the domestic demand profile.

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Demand almost always varies over the course of a day.

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And you can model it in one of two ways

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using demand categories or transfer nodes

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leakage can be constant or vary over the day.

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When modeling demand in info works. WS pro

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the demand and leakage are only calculated from the notes.

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The demand diagram window is used to edit demand categories.

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A demand category defines a 24 hour demand profile which is to be applied

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at the nodes for each type of user such as customer demand or leakage

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demand categories allow for different demand patterns across a

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day of the week or daily slash monthly.

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Scaling factors.

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The demand profile can also be updated from live data

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demand profiles are considered to be either factored or direct

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factor.

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Demand is the most common demand type in which we know the volume of water

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consumed over an average day but not how it is used over that 24 hours.

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The volume may be known as total use per property or person per day

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and is typically measured as a volume of water such as cubic meters.

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It may also be known as the average flow rate such as liters per second.

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Best practice is to generate a 24 hour profile and normalize it for an average of one.

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The demand at any given time is the total daily use divided by

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the simulation time step multiplied by the factor at the time step.

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Direct demand is a bit simpler as this demand type is used for monitored customers.

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Generally large consumers

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factories would be one example,

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the volume of water used over time is already known.

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So you would just assign this demand type to a node.

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Direct demand can be scaled if necessary

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transfer nodes are used to model transfers of water into or out of a network.

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Examples would include network transfers,

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bleeds or the output of a treatment works.

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However,

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these cannot be used as the only source of water in a network as

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a source of pressure input is necessary such as a reservoir or fixed head

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transfer notes can also be used to represent large customers.

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But this is not recommended if the direct demand category is available

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info

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works.

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W S pro uniquely supports customer points which can represent individual

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customer properties and allow for a more accurate demand allocation.

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Customer points link to a pipe which in turn links to a node.

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This allows for more complex modeling

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adjustment of demands and finer scale analysis

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demand can also be manually allocated to nodes similar to

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how it is done in info water or EPA net.