About model calibration and criteria

Model calibration is the process of iteratively adjusting model input parameters to achieve a reasonable match between model output and field data.

Increases accuracy of model in predicting existing conditions within reasonable margins of error, which is vital for use as a planning tool.

Required for accurate fire flow, water quality, and energy analyses in InfoWater Pro model.

Provides understanding of how water moves through system.

Confirms:

• Connectivity
• Pump curve accuracy
• Controls
• Hydrant calibration

Model Calibration Notes:

Two types of calibration: extended-period simulation (EPS) calibration and steady-state calibration.

EPS calibration:

• Compares tank levels, pump run times, junction pressures, and known flows to field data, generally over 24- to 48-hour simulation
• Validates system connectivity, diurnal demand patterns, and system controls

In most cases, goal is hydraulic grade line elevations (HGLEs) within 5-10 feet of field values, and tank level fluctuations within 3-6 feet of field values.

Also want to be able to explain discrepancies found when comparing model data with field data.

Steady state calibration, or hydrant flow calibration:

• Compares pressures at residual hydrants against those in model when introducing hydrant flows as “point demands.”
• Field data from standard hydrant flow tests used to verify whether pressure predictions of model are within 5- to 10-ft HGLE range.
• Utilizing multiple hydrants provides multiple points of data to compare.

When performing hydrant flow tests for calibration, flows to which you are calibrating need to be less than required fire flow values.

Otherwise, may not be calibrating model sufficiently to test all fire flow concerns the model needs to predict.

Ideal is to have calibration flows as high as fire flow requirements—ensures you are calibrating within the necessary range of flows.