Data Review, Calibration, and Results Analysis

All the survey data and discharge information have been developed, the field inspections for n values and flow patterns have been made, and all the input data have been encoded to HEC-RAS or a similar program. All that's left is to let the program crank out the answer for the modeler to prepare the report-right? Wrong. The expression "garbage in-garbage out" still holds true.

Almost anyone can stick numerical data into a program and eventually get a completed output, but that does not mean the output is accurate. A skilled modeler must produce an analysis with a hydraulic model that stands up to technical review by one's peers or the client. While the program may run to conclusion, a lack of quality engineering input or a poor model calibration may be readily apparent with even a casual review.

This chapter concentrates on model development, operation, calibration, and quality control, highlighting the checks of input data made by HEC-RAS. Debugging and calibration techniques are discussed as well as an explanation of how to evaluate production runs. It also details how to develop routing data to use in HEC-1, HEC-HMS, or other hydrologic programs such as PondPack.