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Overview of Butte Creek. Butte Creek. Length: 15.7 miles Lateral Structures: 27 miles Structures: 10 bridges Peak Flowrate : 14,800 cfs (Jan 2006) Elevation Range: 294’ to 76’ Avg Slope: 0.2%. Model Deliverable Files. Documentation Form QC Form and Responses Bridge Data Forms
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Overview of Butte Creek Butte Creek • Length: 15.7 miles • Lateral Structures: 27 miles • Structures: 10 bridges • Peak Flowrate: 14,800 cfs (Jan 2006) • Elevation Range: 294’ to 76’ • Avg Slope: 0.2%
Model Deliverable Files • Documentation Form • QC Form and Responses • Bridge Data Forms • Selected GIS Files • HEC-RAS Files • Bridge Photos
Summary of Model Construction • Cross Sections • Bathymetry Data • Manning’s n • Chow and ground cover from aerial • 0.025 “bare” ground • 0.030 crops • 0.035 channel “common features” • 0.050 “heavy” natural vegetation • Bridge Structures • Lateral Weirs
Summary of Model Construction – cont. • HEC-GEO RAS to build HEC-RAS elements
Summary of Model Construction – cont. • Boundary Conditions • US Flow Hydrograph • DS Normal Depth • Flow Data • Corrected Flows from MBK
Significant Model Elements • Bridge at 30.526 • Rebuilt after aerial image • Skewed • Long span • Lateral Weirs
Significant Model Elements • Bridge at 36.883 • Multiple Bridge • Highway and Railroad
Major Model Development Issues • Invert verification • lateral weir / bridge interaction • ineffective flow definitions
Summary of QC Process • Internal Team, internal pass to the right, Independent and Atkins/DWR. • documentation/additions within HEC-RAS, QC form, HEC-RAS model changes and adjustments
Summary of Calibration • Matched WSE at Gage location within 1.0’ • Adjusted Manning’s n • Refined/simplified ineffective flow areas • HHCWG weir coefficients • Modeling approach at bridge openings
Review of Results • Max WSE • Lateral Structures • Observed HWM • Bridge Structures • Side Tributary