Using customer meters for calibration

If you only use customer consumption to calibrate the hydraulic model, what can happen in the calibration?

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  • If you assume that all of the discrepancies between the model and the field data are due to customer consumption, you may miss serious errors in data collection, pipe roughness, connectivity,... The key to calibration is determining WHY the model and field data differ and fixing that issue.

    Sometimes you may improve calibration for a single data set by adjusting the wrong parameter but this will give you a worse model and it will show up in other data sets. This is what I call "Calibration by compensating errors."

    Here is a list of some of the reasons that calibration might need additional work. How confident are you that all of teh discrepancies are due to consumption?

    Physical

    Pipe size/location

    Pipe connectivity

    Pipe roughness

    Pressure zone boundary

    Pump curves

    Pipe material/age in GIS

    System changes since model built

    Elevation data

     

    Operational

    Valve open/closed/throttled status

    Control valve operation/settings

    Transient events

    Actual operations not matching control rules

    Unusual operations when data were collected

    Tank water levels

    Pump status/speed

    Lack of sufficient sensors/gages

    Water quality reaction rates

     

    Demands

    Spatial allocation

    Model does not reflect conditions when data collected

    Large customers with atypical demand patterns

    Not accounting for seasonal changes in demand

     

    Data

    Inaccurate/uncalibrated gages/meters

    “Latched” data from SCADA

    Understanding SCADA data – average vs. instantaneous

     

  • If you use the flow provided together with the consumption of the customers' meters, will the model understand that the difference could be water losses?

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