Models are usually calibrated against known flood or tidal conditions with the bed resistance coefficient (eg. Manning’s n) adjusted until calculated water levels and flows are consistent with recorded field measurements. Where there is poor or insufficient topographic data the calibration procedure may also involve adjustments to the model topography to provide an adequate representation of the recorded flow behaviour. This is more common in 1D domains (where there is a choice of cross-sections to define a flowpath). There is usually little opportunity to adjust topography (from that surveyed) in 2D domains.
Ideally, the model would be calibrated for conditions similar to those under investigation although this is not always possible, particularly when major floods are being considered. In these situations, a sensitivity analyses maybe carried out by increasing and decreasing calibration factors such as Manning’s n.
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