Calibration For calibration event adjust model parameters to obtain a good fit with the gauged flows. The observed gauge calibration flow data contains baseflow which should be separated before uploading to HEC HMS and for comparison with HEC HMS computed flows at the catchment outlet. The roughness and manning n are adjusted to get the best fit between observed calibration gauge flow data and the HEC HMS computed flows at the catchment outlet Verification For verification event without any further adjustment to model parameters (roughness, and manning n), check if a good fit is obtained with the verification gauged flows. The same values of roughness, and manning n should be used for calibration and verification. If a good fit is not obtained redo the calibration and verification with revised model parameters (roughness and manning n) so that a good fit is obtained with observed gauged flows for both calibration event and verification events. As before, baseflow needs to be separated from the observed gauge verification flow data. Following calibration and verification determine the 1% AEP discharge