Urban Developer scenario calibration

A UD Scenario models the demands generated be each end-use within a dwelling (or multiple dwellings). Demand behaviour depends on the probability of an end-use event occurring at a particular time of the day and the volume usage or efficiency of the end-use.

Each Water Use node in the UD Scenario can be configured according to the number of dwellings, occupancy and end-use types represented by that node. Water supply sources and discharge paths can be allocated. This includes the ability to add a Tank which is supplied from a Roof.

Parameters for calibration

Calibrating demands within the UD Scenario involves a manual review of all variables which can be configured at the Water Use node. e.g.

• No of dwellings
  • while generally pre-determined and well defined, it is possible that this could be miscounted which can impact on total modelled demands
• Occupancy
  • over- or under-estimation of occupancy can impact on total modelled demands
• Indoor end-use efficiency and event distributions
  • although the defaults applied in the Source UD Plugin are taken from researched values derived for Australia by Roberts (2005), these values should be reviewed to ascertain that they adequately represent use within a specific study area
• Supply source proportions
  • distribution of supply from tank and mains can impact on, for example, the comparison of modelled mains demands to observed mains demands
• Outdoor demand
  • outdoor demand (excluding Pool) depends on the representation of a user-specified demand and is more variable than indoor demands. According to Roberts (2005) outdoor demands can account for approximately 25% of annual demand.

Which of the variables is most sensitive will depend on the available observed demands, for example, calibrating to a time series of observed mains demands can be affected by the configuration of all the variables listed above.