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.