CLASS PLAN

• RIVER BEHAVIOR

• FLOW GAUGING

• MANNING’S EQUATION

• BANKFULL DISCHARGE

• DISCUSS MCPHEE

RIVERS

• On Huntington, in water

• Warm clothes, food, $, Daily Bread

• Measure discharge - survey and velocity

• Trace flow

• Compare pools and riffles

• Field estimate of bankfull stage

Idealized flow patterns

Alluvial, meandering

river

Dye tracing

Channel MobilityWatts Branch, MD

Downstream OrganizationSurvey one of each type

Calculate discharge for one of each typeCOMPARE

FLOW GAUGING

• QUANTIFY VOLUME OF WATER MOVING THROUGH CHANNEL

• NEED CHANNEL GEOMETRY

• NEED VELOCITY

Distance

Velocity

Water Depth

Survey Across Stream

Flow meter for measuring water speed

Divide and Conquer

Add up the pieces

From counts to speed

Manning Equation

SLOPE

Wetted Perimeter

Flow Levels

Bank full flowAbout once a year

Try to define in field usingobservations

Extreme FloodsHow does the Huntington Fit?

DEFINE BASIN AREA

COUNT BOXESOR USE

DIGITIZER

Sediment Transport Through Rivers

Bedload -- material moving along the bed, shear forces exerted by water sufficient to move clasts

Suspended Load -- material kept in the water column by turbulence and lift forces

Bedload usually <<< than suspended load and ignored

Dissolved Load -- material kept in the water column by turbulence and lift forces

Dissolved load varies, usually <<< than suspended load

Sampling for suspended load…….

QuickTime™ and aSorenson Video decompressorare needed to see this picture.

Mass Loadings and Erosion Rate Estimation

Integrate suspended load over all flows (mass/time)

Integrate bedload load over all flows (mass/time)

Integrate dissolved load over all flows (mass/time)

+

+

Integration over all flows is a non trivial problem!

Need Rating Curves (suspended, dissolved, bedload)

Other Approaches…Reservoir trapping

Nahal Yael, Negev Desert

SEDIMENT YIELD - What comes out

SEDIMENT GENERATION - Material generated by erosion

= or ≠TimescaleSteady stateHuman impactEpisodic disturbance

1. Describe the Atchafalaya River

2. What is the geologic origin of southern Louisiana?

3. What is "capture"?

4. What is and how does the "hold by levee" philosophy work? Is this philosophy still followed today?

John McPhee -- Control of Nature