CLASS PLAN RIVER BEHAVIOR FLOW GAUGING MANNINGS EQUATION

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 Mobility Watts Branch, MD

Downstream Organization Survey one of each type Calculate discharge for one of each type COMPARE

FLOW GAUGING • QUANTIFY VOLUME OF WATER MOVING THROUGH CHANNEL • NEED CHANNEL GEOMETRY • NEED VELOCITY

Survey Across Stream Distance Velocity Water Depth

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 flow About once a year Try to define in field using observations

Extreme Floods How does the Huntington Fit?

DEFINE BASIN AREA COUNT BOXES OR 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 Dissolved Load -- material kept in the water column by turbulence and lift forces Bedload usually <<< than suspended load and ignored Dissolved load varies, usually <<< than suspended load

Sampling for suspended load…….

Mass Loadings and Erosion Rate Estimation Integrate suspended load over all flows (mass/time) + Integrate bedload 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 = or ≠ Timescale Steady state Human impact Episodic disturbance SEDIMENT GENERATION - Material generated by erosion

John Mc. Phee -- Control of Nature 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?