40 likes | 58 Views
From Fread, D.L., Flood routing models and the Manning n. 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.
E N D
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.