Post on 24-Feb-2016
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FLUID EARTH
The hydrologic cycle
Water Budget….p 244-246
Sources of Earth’s water
Stream FEATURES
Headwaters Beginning of a stream; high elevation.
Watershed Land from which water runs off into a
stream.
Tributary Feeder stream that flows into a main
stream.
Divide Elevated region that
separates 2 watersheds.
Coasta
l Plai
n
Floodplain Area that
may be covered with water during a flood.
Meander - E Wide curve in a stream channel.
Erosion & Deposition along a meandering stream
Cut Bank - E The area of active erosion on the OUTSIDE
of a meander.
Point Bar - D A crescent-shaped accumulation of sand
and gravel deposited on the INSIDE of a meander.
Oxbow Water remaining in an isolated meander in a
floodplain.oxbow lake formation
Delta - D Fan-shaped deposit of sediments at the mouth of
a stream formed when rivers erode and transport sediments. When the river slows down, it deposits sediments.
EROSION of Streams
Headward Stream erodes
away at the rock and soil at its headwaters in the opposite direction that it flows Niagara Falls
Downcutting Deepening the
channel of a stream by removing material from the stream's bed.
Meandering Formed when the
moving water in a river erodes the outer banks and widens its valley.
SEDIMENT in Streams
Bed Load Particles in a
flowing fluid (usually a river) that are transported along the bed
Suspended Load Fine particles that are light enough to be
carried in a stream without touching the stream bed.
Dissolved Load Material,
(especially ions from chemical weathering), that are carried in solution by a stream.
Stream CALCULATIONS
Gradient Steepness of slope. Change in elevation over a
distance.
Elevation Drop Horizontal Distance
◦ Feet/Mile
Example:◦ 50ft. Drop / 5 miles = 10ft./mile
Gradient
Gradient
How river systems change from young to mature!YOUNG MATURE
Wide Channels Large floodplains Lateral erosion Gentle slopes Meanders,
oxbows Fine sediment
Life Cycle of a River Overview
Narrow channels Small floodplains Downcutting Steep slopes Rapids,
waterfalls Coarse sediment
YOUNG Stream V – shaped valleys Erodes away at bed
(more than sides) Waterfalls and
Rapids are common.
Few Tributaries
OLD Rivers Well established tributaries Drains effectively Carries LARGE amounts of water Does not get deeper, (Erodes from Sides)
FLOODS Stream overflows channel Causes
◦ Weather events◦ Dams break
(+) Provides “fertilizer” for floodplain (-) Most destructive of all geologic hazards
Describe human decisions that increase the risk of flooding. Disturbing vegetation that uses water and
returns it to the atmosphere before flooding occurs.◦ Building◦ Grazing animals◦ Farming practices like clear-cutting land◦ Cutting down forests
Cincinnati, OH
3 ways to prevent floodingLook over attached handout: Dams Artificial Levees Channels
Great Lakes drainage basin
Most polluted areas, according to the Great Lakes Water Quality Board
“Hot spots” of toxic concentrations in water and sediments
Eutrophic areas
CANADA
WISCONSIN
MINNESOTA
IOWA
ILLINOISINDIANA OHIO
PENNSYLVANIA
NEW YORK
MICHIGAN
MICHIGAN
Nipigon Bay
Thunder Bay
Silver Bay
St. Louis R.
Jackfish Bay
St. Mary’s R.Spanish R.
Penetary Bay
Sturgeon Bay
SaginawBay
Saginaw R. System
St. Clair R.Detroit R.Rouge R.Raisin R.
Maumee R.
Black R.Rocky R.
Cuyahoga R.Ashtabula R.
Thames R.
Grand R. Niagara Falls
Niagara R.Buffalo R.
St. Lawrence R.
Fig. 19.7, p. 484
http://techalive.mtu.edu/meec/module08/GreatLakesFlow.htm
Great Lakes Watershed
http://www.ofps.ucar.edu/gapp/networks/images/greatlakes_map.jpg
Trace the path(s) that 99% of water travels through the Great Lakes watershed.