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Learn effective calibration methods for accurate representation, stability, and matching observed data in flood routing models. Follow expert tips for calibration, focusing on flow dynamics and decomposing river systems.
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Calibration Objectives • Develop an accurate representation of the physical system • Match observed stages and discharge as closely as possible • Maintain computational stability over a wide range of hydraulic conditions Bullets adapted from RTi (2007) Report on “Calibration for the Lower Tar River Basin”
Additional Calibration Tips • Calibrate for at least 2 years of data if possible. Additionally, calibrate drought and historic peak conditions if possible* • Check water balance on total inflows and outflows. If not within 5-8%, local ungaged flows need to be modified.* • When possible, focus on events where you have confidence that ungauged flows from the hydrologic models are correct (use observed flow data where it is available)** • See next slide with pointers on decomposing a river system into calibration reaches • When roughness as a function of flow, be aware that drastic changes in roughness from one interval to the next can result in model stability problems * From NWS Notes by Janice Sylvestre ** From RTI (2007) “Calibration for the Lower Tar River Basin”
Fread and Smith (1978) suggest calibration from upstream to down stream Decomposing a river system for calibration Fread, D.L., Smith, G.F., Calibration Technique for 1-D Unsteady Flow Models, Journal of the Hydraulics Division, 1978.