streams and rivers stream erosion and deposition river valleys flood plains and floods surface water
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Streams and Rivers
Stream Erosion and Deposition
River Valleys
Flood Plains and Floods
Surface Water
Tigris – Euphrates River
The Nile River
Yangtze River
Ganges River
Amazon River
The Mississippi River
Water Phase Changes
Hydrologic Cycle
A river system consists of a river and all
of its tributaries.VOCABULARY
The drainage basin of a river system is all the land that
is drained by the river and its tributaries. A river’s
velocity, gradient, discharge, and channel shape affect
how it erodes and transports materials.
Streams and RiversSurface Water
Tributary
River
Divide
tributary
river system
drainage basin
watershed
divide
gradient
discharge
Important Definitions
____________ – a stream and all its tributaries
________ – a smaller stream that empties into a larger stream
_________ – the land area drained by a river system
______ – a high point that separates river systems
River System
Tributary
Watershed
Divide
River Channels and Drainage
There are different types of river channel patterns and river drainage patterns.
1. Dendritic
2. Radial
3. Rectangular
4. Trellis
Dendritic networkA drainage network whose interconnecting streams resemble the pattern of branches connecting to a deciduous tree
Radial network
A drainage network in which the streams flow outward from a cone-shaped mountain, and define a pattern resembling spokes on a wheel.
Rectangular network
A drainage network in which the streams join each other at right angles because of a rectangular grid of fractures that breaks up the ground and localizes channels.
Trellis network
A drainage system that develops across a landscape of parallel valleys and ridges so that major tributaries flow down the valleys and join a trunk stream that cuts through the ridge; the resulting map pattern resembles a garden trellis.
Rivers wear down Earth’s surface and
erode and deposit materials. A river
may carry materials in solution, in
suspension, and in its bed load.
VOCABULARY
Stream Erosion and Deposition
Surface Water
Flow
Suspension:Silt and clay
Bed load: sand, gravel,pebbles and boulders Materials carried in
solution cannot be seen.
deposition
pothole
load
suspension
bed load
competence
capacity
delta
Stream LoadA stream can carry its load in three
different ways:
1.________ – material is dissolved 2.__________ – particles are held up by
stream’s moving water3._________ – material pushed or rolled
along the stream’s channel
solution
suspension
bed load
How Streams Move Sediment
Velocity and discharge affect how much
material a river can transport. When river
velocity greatly decreases, sediment drops out
of the water to form a delta or alluvial fan.
Stream Erosion and Deposition
Surface Water
Over time, sediments build up, forming a delta.
Stream Discharge
Discharge is the amount of water that flows past a point in a certain amount of time.
Discharge is dependent upon velocity, depth, and width of the stream.
Discharge = _______ x _____ x _____velocity depth width
Vocabulary Summarydeposition pothole load capacity delta
A process by which materials is dropped, such as sand or silt by a stream;
Deep oval or circular basins cut into a stream or river bed by abrasion from swirling sand, pebbles, and small boulders.
The eroded rock and soil materials that are transported downstream by a river.
A measure that describes the maximum size of the particles a stream can carry.
A fan-shaped deposit that forms when a river flows into a quiet or large body of water, such as a lake, an ocean, or an inland sea.
RIVER DEPOSITION
A river drops some of its load when either its volume or its speed decreases eg when it enters an arid (dry) region, crosses an area of porous rock (eg limestone), enters a flat or gently sloping plain or enters a lake or the sea.Material transported or deposited by a river is called alluvium.
____________ – deposit formed when a stream spreads out onto a less steep area
Alluvial Fan
_____ – where a stream empties into a larger body of water
Delta
Stream Stages
________:
RapidsWaterfallsFast-moving
waterSteep slope
_______:
Broad floodplain
MeandersOxbow lakesMeander Scars
Youthful Old
River Systems
Youthful
Mature
Old
Stream Processes and Floodplain Development
Youthful rivers form steep-sided canyons and V-
shaped valleys. The lowest level to which a river
can erode its bed is called its base level.
River ValleysSurface Water
Rapids can form as a
river runs down a deep
slope, while a river that
plunges over a cliff
forms a waterfall.
River Valley Terms
Headward erosion
Base level Stream piracy
The process by which land is worn away at the head of gully or stream valley.
The level of the body of water into which a stream flows.
The diversion of the upper part of one stream by the headward growth of another stream.
____________ – when an old age stream downcuts to “make it new again”
Rejuvenation
Forming Stream Terraces
floodplain
A river that has cut down close to its
base level tends to erode the sides of
its valley, forming a meandering river
in a wide flood plain.
VOCABULARY
Floodplains and Floods
Surface Water
Back swampValley wall
Oxbow lake
Meander
Natural levees
Yazoo tributary
flood
floodplain
meanders
oxbow lake
natural levees
flash flood
________ – the bends and curves of a stream
Meanders
Oxbow lake
deposition
erosion
Oxbow Lakes
Oxbow Lakes
River floods are natural events that can have
constructive as well as destructive effects.
Floodplains and Floods
Surface Water
People
have
developed
different
methods to
control and
prevent
river
flooding.
Floodplain and Natural Levee Development
Mississippi River Flood
1993 Before and After
Vocabulary Review
Flood: The phenomenon whereby a river overflows its banks.
Flood plain: A wide, level area that borders a river and is covered by its water during a flood.
Meander: Broad: looping bends in a river.Oxbow lake: A crescent-shaped body of water
formed when sediments deposited by a river cut off a meander from the river.
Natural levees: Elevated ridges along a river’s bank that are formed by the deposition of the river’s sediment load.
Flash flood: A sudden flood, usually caused by intense, heavy rainfall.
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