Lecture 12
Streams and Floods
Lecture Outline
I The Hydrologic Cycle
IIDefinitions
III
Drainage
A)
Runoff
i.
ii.
B)
Drainage Basins
i.
ii.
C)
D)
Mississippi River Drainage Basin
Chesapeake Bay Drainage Basin
Stream Order
Drainage Patterns
i.
ii.
iii.
iv.
E)
Channel Flow
Sheet Flow
Dendritic
Radial
Rectangular
Trellis
Stream Valley Development
i.
Base Level
Lecture 12
i
Lecture Outline
III
E)
Drainage
Stream Valley Development
ii.
iii.
iv.
IV
A)
Stream Function
Controls on Stream Function
i.
ii.
iii.
iv.
B)
C)
D)
The Graded Stream
Lateral Erosion
Headward Erosion
Velocity
Channel Properties
Gradient
Discharge
Erosion
Transportation
Deposition
i.
ii.
iii.
Bars
Braided Streams
Meandering Streams and Point Bars
Lecture 12
ii
Lecture Outline
IV
D)
Stream Function
Deposition
iv.
v.
vi.
V
A)
B)
C)
Flood Plains
Deltas
Alluvial Fans
Other Fluvial Morphologies
Stream Terraces
Incised Meanders
Superposed Streams
Lecture 12
iii
The Hydrologic Cycle
Lecture 12
I
Definitions
stream - a body of water found on Earth's surface and confined to a
narrow topographic depression, down which it flows and
transports rock particles, sediment, and dissolved particles.
Rivers, creeks, brooks, and runs are all streams.
Lecture 12
II
Runoff
Channel Flow
Sheet Flow
Lecture 12
III.A
Runoff
Overland (Sheet) Flow
Lecture 12
III.A
Drainage Basin
drainage basin -
the total land surface drained by a system of
streams leading to the same outflow.
drainage system - the streams, tributaries, and other bodies of
water by which a region is drained.
drainage divide - the boundary between adjacent drainage basins.
Lecture 12
III.B
Drainage Basin
Mississippi River and Chesapeake Bay
Lecture 12
III.B.i
Stream Order
stream order - a classification of
relative position of streams in a
channel network, assigning
each link an integer order
number determined by the
pattern of confluences in the
tributary network headward of
the given link.
Lecture 12
III.C
Stream System Components
Lecture 12
III.C
Drainage Patterns
Dendritic
Radial
Rectangular
Trellis
Deranged
Lecture 12
III.D
Drainage Patterns
Dendritic
Lecture 12
III.D.1
Drainage Patterns
Radial
Lecture 12
III.D.2
Drainage Patterns
Rectangular
Lecture 12
III.D.3
Drainage Patterns
Trellis
Lecture 12
III.D.4
Drainage Patterns
Deranged
Lecture 12
III.D.4
The Stream Valley
Lecture 12
III.D.4
Stream Valley Development
Evolution
Lecture 12
III.E.iii
Stream Valley Development
Stream Profile
Base Level/Grade
Lateral Erosion
Headward Erosion
Lecture 12
III.E
Stream Valley Development
Base Level
Lecture 12
III.E.i
Stream Valley Development
The Graded Stream
graded stream - a stream
maintaining an equilibrium
between the processes of
erosion and deposition,
and therefore between
aggradation and
degradation.
Lecture 12
III.E.ii
Stream Valley Development
Lateral Erosion
Lecture 12
III.E.iii
Stream Valley Development
Evolution – Headward Erosion
Lecture 12
III.E.iii
Stream Functions
Erosion
Transportation
Deposition
Lecture 12
IV
Controls on Stream Function
Velocity
Channel Properties
Gradient
Discharge
Lecture 12
IV.A
Controls on Stream Function
Velocity
Lecture 12
IV.A.i
Controls on Stream Function
Channel Properties – Cross-Sectional Area
Lecture 12
IV.A.ii.1
Controls on Stream Function
Channel Properties – Longitudinal
Organization
Straight Channel
Meandering Channel
Braided Channel
Lecture 12
IV.A.ii
Controls on Stream Function
Straight Channel
Lecture 12
IV.A.ii
Controls on Stream Function
Meandering Channel
Lecture 12
IV.A.ii
Controls on Stream Function
Braided Channel
Lecture 12
IV.A.ii
Controls on Stream Function
Gradient
Lecture 12
IV.A.iii
Controls on Stream Function
Discharge
discharge : volume of water flowing past a point in a given amount of time.
Lecture 12
IV.A.iv
Erosion
Lecture 12
IV.B
Sediment Transport
capacity:
the total volume of
sediments a stream can
carry; a function of
discharge
competence: the maximum size of
sediment the stream
can carry
Transport Modes
1Suspended
2Bed
load
load
3Dissolved
load
Lecture 12
IV.C
Depositional and Other Fluvial
Landforms
Flood Plains
Meandering Stream
Point Bar
Cutbank
Oxbow Lakes
Natural Levees
Overbank Deposits
Yazoo Tributary
Backswamps
Bars
Braided Streams
Deltas
Alluvial Fans
Lecture 12
IV.D
Flood Plains
Lecture 12
IV.D.iv
Meandering Streams and Point Bars
Lecture 12
IV.D.iii
Meandering Streams and Point Bars
Lecture 12
IV.D.iii
Meandering Streams
Migration
Lecture 12
IV.D.iii
Meandering Streams and Oxbow Lakes
Lecture 12
IV.D.iii
Flood Plains
Natural Levees
Natural levees
Lecture 12
IV.D.iv
Bars
Lecture 12
IV.D.i
Braided Streams
Lecture 12
IV.D.ii
Deltas
Lecture 12
IV.D.v
Deltas
Lecture 12
IV.D.v
Alluvial Fans
Alluvial Fan (Death Valley, CA)
Lecture 12
IV.D.vi
Other Fluvial Morphologies
Stream Terraces
Incised Meanders
Superposed Streams
Lecture 12
V
Stream Terraces
Lecture 12
V.A
Incised Meanders
Lecture 12
V.B
Superposed Streams
Lecture 12
V.C