1. From Fread, D.L., Flood routing models and the Manning n

2. 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”

3. 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”

4. 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.