Lecture 16 Surface water flow Hydraulic radius and

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Lecture 16 Surface water flow

Lecture 16 Surface water flow

Hydraulic radius and roughness parameter •

Hydraulic radius and roughness parameter •

Consider this channel: 2 ft 20 ft What is the wetted perimeter? What is

Consider this channel: 2 ft 20 ft What is the wetted perimeter? What is the hydraulic radius? The discharge is 400 ft 3/sec, what is the velocity? (show all units)

Uniform flow: flow that does not change with distance downstream, neither in area nor

Uniform flow: flow that does not change with distance downstream, neither in area nor velocity Varied or nonuniform flow: flow that changes with distance down stream

Speed of water •

Speed of water •

Friction and drag • Imagine bottom of stream with clasts (rocks) •

Friction and drag • Imagine bottom of stream with clasts (rocks) •

Stream power •

Stream power •

Friction Factor •

Friction Factor •

Balance of gravity and friction forces •

Balance of gravity and friction forces •

Derivation of Manning’s Equation

Derivation of Manning’s Equation

Velocity Distribution •

Velocity Distribution •

Gradually- and Rapidly-varied Flow •

Gradually- and Rapidly-varied Flow •

Equations of Motion •

Equations of Motion •

Hydraulic Jump •

Hydraulic Jump •

Measuring stream flow USGS steam gauges with “real time” data http: //waterdata. usgs. gov/ny/nwis/rt

Measuring stream flow USGS steam gauges with “real time” data http: //waterdata. usgs. gov/ny/nwis/rt

Measuring stream flow Discharge – reported in cfs by the USGS Or, not measure

Measuring stream flow Discharge – reported in cfs by the USGS Or, not measure at every “X, ” but instead Just measure at 60% of water depth

Measuring stream flow Discharge – reported in cfs by the USGS Stage – height

Measuring stream flow Discharge – reported in cfs by the USGS Stage – height of water in a creek. Measured with respect to some datum

Measuring stream flow Discharge – reported in cfs by the USGS Stage – height

Measuring stream flow Discharge – reported in cfs by the USGS Stage – height of water in a creek. Measured with respect to some datum. Based on the notion that it is easier to measure stream height (dipstick) than discharge. Founded on relationship intrinsic to the specific river of discharge versus stage (rating curve)

Measuring stream flow

Measuring stream flow