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Bulk Urban Demand Model calibration in Source

Calibrating bulk water demands begins with the calibration of individual demands at a demand template in a UD Scenario.  Once it has been ascertained that these sufficiently represent each particular demand combination, for example, detached houses with pools, these individual demands can be combined to represent bulk water demands in an urban demand system within a Source scenario. The spatial and temporal distribution of demands across the bulk water system is modelled at a WU node in the Source catchment or river system scenario. This includes the number of dwellings, the probability of dwellings occurring with a specified occupancy (0 – 6 occupants), and the probability of each end-use occurring within a dwelling. These probabilities can be varied over time as occupancy rates change, water restrictions[1] are introduced/removed or as end-use efficiencies improve.

The discussion of urban demands thus far has focussed on residential urban demands. Demands generated at a UD Scenario template provide for indoor and outdoor residential demands but not for non-residential urban demands (public use areas such as parks and sports grounds and commercial and/or industrial demands) and nor for non-revenue water e.g. fire hydrant use or losses due to leaks. These non-residential and non-revenue earning components of total demand form part of the base component of urban demand, although non-residential demand can also have a variable component related to e.g. park watering.

Model calibration therefore should take into consideration:

  • base demands – including components of both residential and non-residential demands
  • and climate variable indoor[2] and outdoor demand components – also considering the impact of restrictions on outdoor demands
  • non-revenue water

[1] Restrictions can be applied to Outdoor demands using a Function on the Scaling Factor.

[2] Evaporative cooling is an example of a variable indoor end-use which has not yet been modelled explicitly in the UD Behavioural node. This will be facilitated by the option to add a custom end-use. It can also be added as a new configuration on the Urban Behavioural Demand in a Source Water User node.