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
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 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 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…….
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 ≠ Timescale Steady state Human impact Episodic 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