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RUNNING WATERPhysical Geology
The Walker School
Distribution of Earth’s Water
1.36 billion km3 of water on Earth
Hydrologic Cycle
Fig. 15-3, p. 460
Water Characteristics
•Flow
•Viscosity
•Infiltration Capacity
•Gradiant
Water Cycle Statistics
85% of water enters the atmosphere each year
from the upper 1 m layer of the ocean through
evaporation.
80% of the Earth’s precipitation falls back into the
oceans.
36,000 km3 falls on land each year and eventually
returns to the oceans.
Laminar Flow
Fig. 15-4a, p. 461
Turbulent Flow
Fig. 15-4b, p. 461
Streamlines are the paths taken by water molecules.
Stream Gradient
Fig. 15-5, p. 462
Water moves more
slowly with greater
turbulence near a
channel’s bed and
banks because of
friction.
Running Water, Erosion and Sediment
Transport
Fig. 15-7b, p. 464
Sediment from talus cones.
Sediment loading from a river’s banks.
Sediment Transport and Deposition
Fig. 15-9a, p. 466
Note:
1. Bed Load
2. Suspended Load
3. Dissolved Load
Relation to Particle Size and Density
Fig. 15-9b, p. 466
Fig. 15-9, p. 466
Braided StreamGrinelwald, Switzerland
Fig. 15-10b, p. 467
Develop when
sediments exceed
transport capacity.
Characterized by
broad, shallow
channels and bed-
load transport.
Meandering Streams
Fig. 15-11, p. 468
Deposits are
mostly mud
deposits on
flood plains.
Flood Plain Deposits
Fig. 15-14, p. 471
Natural levees build up by
repeated deposition of sediments
during numerous floods.
Marine Delta – Stream Dominated
Fig. 15-16a, p. 472
Mississippi River
delta on the U.S. Gulf
Coast is stream
dominated.
Mississippi Delta Formation
p. 495
Erosion over
millions of years
produced 7
different alluvial
fans which add
land mass to the
continent.
Marine Delta – Wave Dominated
Nile delta is wave
dominated.
Marine Delta – Tide Dominated
Ganges delta is tide
dominated.
Alluvial Fans and their Deposits
Formed during periodic rain storms.
Surface run-off is typically funneled into mountain canyons.
The run off is confined so it can’t spread latterly.
Repeated deposits create alluvial fans.
Types of Floods
Table 15-1, p. 474
Flash flood in West, VA.
Why do people build in flood zones?
Fertile soils
Level surfaces
Proximity to water for agriculture and industry.
Fig. 15-18, p. 474
WHAT TECHNOLOGY IS USED
TO MONITOR WATER LEVELS?
Samples Hydrograph
Fig. 15-19, p. 475
Flood Frequency Curve
Fig. 15-20b, p. 475
Note: Meteorologists
typically watch for 2, 5,
10, 20 and 100 years
floods.
Flood of 1993
Caused by
intersection of the
jet stream and air
masses over the
Midwest.
Responsible for 50
death and
displaced 70,000
people.
Concept Art, p. 476
World’s Largest Floodshttp://pubs.usgs.gov/circ/2004/circ1254/
HOW CAN TECHNOLOGY BE
USED TO CONTROL
FLOODING?
Flood Control Methods
Dams and Reservoirs
Levees
Floodways
Floodwalls
Fig. 15-21a, p. 478
World Drainage Basin
An area which a stream or river and its tributaries carry all surface runoff.
Ocean Drainage Basins
The Atlantic Ocean drains approximately 47% of
all land in the world.
The Pacific Ocean drains just over 13% of the land
in the world.
The Arctic Ocean basin drains most of Western and
Northern Canada east of the Continental Divide.
The Indian Ocean drains around 13% of the Earth's
land.
The Southern Ocean drains Antarctica.
River Basins
The three largest river basins (by area), in order of largest to smallest, include the Amazon basin, the Congo basin, and the Mississippi basin.
The three rivers that drain the most water, from most to least, are the Amazon, Congo , and Ganges Rivers.
Mississippian Drainage Basin
Fig. 15-22b, p. 480
Endorheic Drainage Basins
Inland basins that do not drain into an ocean;
18% of all land drains to endorheic lakes or seas.
The largest of these consists of much of the interior of Asia, and drains into the Caspian Sea and the Aral Sea.
Evaporation is the primary means of water loss
Water is typically more saline than the oceans.
Aral Sea Drainage Basin
Types of Drainage Systems
Fig. 15-23, p. 481
1. Dendritic Drainage
2. Rectangular Drainage
3. Trellis Drainage
4. Radial Drainage
5. Deranged Drainage
WITH WHAT GEOLOGICAL
FEATURES ARE DRAINAGE
SYSTEMS ASSOCIATED?
Drainage Patterns and Geology
Dentritic Drainage
Rectangular Drainage
Trellis Drainage
Radial Drainage
Deranged Drainage
Erosion Deposits
Regional Joint Systems
Folded Sedimentary Rock
Volcanoes
Swamps and Lakes
Canyons and Gorges
Most canyons were formed by a process of long-time erosion from a plateau level.
The cliffs form because harder rock strata that are resistant to erosion and weathering remain exposed on the valley walls.
Canyons are much more common in arid areas than in wetter areas because weathering has a greater effect in arid zones.
A canyon may also refer to a rift between two mountain peaks such as those in ranges such as the Rocky Mountains, the Alps, the Himalayas or the Andes
Grand Canyon, AZ.
Largest Canyons
Grand Canyon in
Arizona, USA
Copper Canyon in
Chihuahua, Mexico
Copper Canyon, Mexico
Deepest Canyons on Earth
The Yarlung Tsangpo Canyon, along the Yarlung Tsangpo River in Tibet, China
Kali Gandaki Gorge in Nepal
Polung Tsangpo Canyon in Tibet
Cotahuasi Canyon (3,535 m deep and the deepest in the Americas)
Hell’s Canyon on the Snake River in Idaho, which is 2400 meters deep
The Tekezé gorge (2000m+ deep and deepest in Africa)
Grand Canyon while the largest canyon in area is only 900 meters deep.
Hell’s Canyon, ID
HOW DO VALLEYS
EVOLVE?
Processes Involved in Valley Formation
Downcutting
Lateral Erosion
Sheet Wash
Headward Erosion
Mass Wasting
Downcutting off the San Juan River
Evolution of a Valley – Part I
Fig. 15-28a, p. 486
The stream widens
its valley by lateral
erosion and mass
wasting, while
simultaneously
extending its valley
by headward
erosion.
Evolution of a Valley – Part II
Fig. 15-28b, p. 486
As the larger stream
continues to erode
headward, stream
piracy takes place
when it captures
some of the
drainage of the
smaller stream.
Stream Piracy
Occurs when headward erosion breaches a divide
and diverts some or all of the drainage of another
stream system.
The Hadhramawt Plateau of
South Yemen exhibits a
complex dendritic drainage
pattern and excellent examples
of "stream piracy”.
A
BA. - Wadi Hadhramawt opens
into the sand-filled Ramlat
Sabatayn in the southwest
corner of the Rub-al-Khali (The
Empty Quarter), B - yet
drainage is toward the sea.
