Why Study Continental
Aquatic Systems?
• Why are you taking this class?
• Human utilization of water – Pressures on a
key resource
• What is the value of water quality?
• Chapter 1…
Human Utilization of Water –
Pressures on a Key Resource
• Only 1% of water in lakes, 0.01% in rivers
• U. S. water use ~2000 m3 per capita per
year
• Much water use for industry and irrigation,
not just home use
• Surface water provides majority of water,
large demand on small proportion of water
Water use
Global water use is
increasing exponentially
Global water use
3
(km per year)
5000
4000
3000
2000
1000
0
1800
1850
1900
Year
1950
2000
Water Availability in the Future
• Of ~30,000 km3 y-1, only ~9,000 is
geographically and temporally accessible
• Currently humans use ½ of what is
accessible
• If all people on earth used water at the same
rate as people in the U.S., all available
water would be used
• Population and resource use rates are
increasing and will do so into the future
What is the Value of
Water Quality?
• Can you list values?
What is the Value of
Water Quality?
•
•
•
•
Global values of wetlands $26.4 trillion y-1
Global values of rivers and lakes $2.5 trillion y-1
Flood control, water supply, waste treatment
People are willing to pay for clean water, property
near clean water and recreation
• Other values include irrigation (40% of world’s
crops), aquaculture, fisheries (particularly in
developing countries)
• Can you think of more?
•
Costanza R, de Groot R, Sutton P, van der Ploeg S, Anderson SJ, Kubiszewski I, Farber S, Turner
RK. 2014. Changes in the global value of ecosystem services. Global Environmental Change 26:
152-158.
Properties of Water
• Chemical and physical properties
• Relationships among water viscosity,
inertia, and physical parameters
• Movement of water
• Forces that move water
• Ch2…
Chemical and Physical
Properties
• Hydrogen bonding
• High density, surface tension, heat of
vaporization, heat capacity, liquid at earth’s
surface, excellent solvent (important for
weathering)
• Ions more soluble in warmer water, gasses less
• Unusual relationship between temperature and
density
Temperature and density of water
Density (g mL-1)
1.000
A
0.999
0.998
0.997
0.996
0.995
0.925
0.900
% density decrease
per 0C increase
0.03
B
0.02
0.01
0.00
-0.01
0
10
20
0
Temperature ( C)
30
Salinity and density of water
Relationships among Water
Viscosity, Inertia, and Physical
Parameters
• Hydrogen bonding becomes more important at
smaller scales, altering both viscosity and inertia
(think of you versus a fly pushing through a spider
web)
• Viscosity is the resistance to change in form
(internal friction)
• Inertia is the resistance of a body to a change in its
state of motion
• Reynolds number incorporates both
Reynolds Number
•
•
•
•
Viscosity Fv = µSU/l
Inertia Fi = p S U2
Re = Fi/Fv = p U l/ µ
Units µ = dynamic viscosity, p = density,
U = velocity, S = surface area, l = length
Dynamic viscosity and temperature
2.5
Viscosity (centipoise)
2.0
1.5
1.0
0.5
0.0
-5
5
15
Temperature (0C)
25
35
Reynolds number for some organisms
Contrast of Properties of Water Varied by Scale
Parameter
Small organism
(< 100 µm)
Large organism
(> 1 cm)
Re
Low
High
Viscosity (Fu)
High
Low
Inertia (Fi)
Low
High
Flow
Laminar or none
Turbulent
Body shape
Variable
Streamlined
Diffusion
Molecular
Transport
(eddy)
Particle sinking rates
Low
High
Relative energy
requirement for motility
High
Low
Movement of Water
• Brownian motion takes place at the finest
scales (atomic to approximately bacterium
size)
• Laminar flow, unidirectional flow
• Turbulent flow, flow vectors in many
directions
• Important concepts, flow boundary layer,
streamlining
A
Solid surface
99% of open
channel velocity
B
Flow boundary layer
Distance from Surface
Flow Boundary Layer
Water velocity
Zero
velocity
Open channel
velocity
Flow Boundary Layer
Direction of current
Outer edge of flow boundary layer
Substrata
Streamlining and Re
A. Laminar
Re < 5
B. Vortices
5 < Re < 100,000
C. Fully turbulent
100,000 < Re
D. Laminar
Re < 20
E. Few vortices
20 < Re < 100,000
Direction of flow
F. Vortices to
fully turbulent
flow
100,000 < Re
Stokes Law
• Sinking rate of small spheres is a function
of size and density of the sphere and
viscosity and density of water
• Cells alter shape to change sinking rate
(Melosira example)
Wikimedia commons
Cell Morphology Alters Sinking Rate
60
Sinking velocity (µm s-1)
50
Sphere (1.25 g cm-3)
Sphere (1.09 g cm-3)
Melosira italica
40
30
20
10
0
0
1
2
3
4
Volume (1000 µm3)
5
6
7
Forces that Move Water
•
•
•
•
Hydrologic cycle (solar energy and gravity)
Wind
Coriolis effect
Organisms (bioturbation)
• Chapter 3.
Spatial Scale and Water Movement
(note these are fuzzy, overlapping areas, more like a gradient)
1010
108
Time (d)
10
Large currents,
hydrologic cycle
6
104
10
2
1 year
Turbulent flow
100
10-2
1s
Laminar flow
Your text
10-4
10-6
10-8
10-9
Molecular
movement
10-7
10-5
10-3
10-1
101
Distance (m)
103
105
107
Movement of Light, Heat, and
Chemicals in Water
• Diffusion in water
• Light and heating of water
Diffusion in Water
• Molecular versus advective transport (also
referred to as eddy diffusion or transport
diffusion)
• Fick’s Law Diffusion = constant * C/ X
• Think about how scale influences diffusion
Molecular diffusion is
really slow
Diffusion Boundary Layer
• Similar to the flow boundary layer, but
defined by the region where molecular
diffusion dominates
• Biogeochemical constraint as well as a
physiological constraint
Surface Area to Volume
alters Diffusion
• Consider two cubes, one 1 µm and one
1000 µm along a side
• Surface areas are 6 and 6000000 µm2
• Volumes are 1 and 1 billion µm3
• Sa/V is 6 versus 0.006, respectively
• How do large organisms deal with
diffusion?
Effect of temperature on diffusion
Diffusion coefficient (cm2 s-1 x 10-5)
2.0
1.6
1.2
0.8
0.4
0.0
-5
5
15
Temperature (0C)
25
35
Light and Heating of Water
• Photosynthesis driven by light
• UV increases are important
• Water is heated by light
Light Attenuation is
Logarithmic
• Assume 1/10th is left after 1 m, 1/100th
after 2 m, 1/1000th after 3 m, etc.
• Attenuation coefficient  describes how
rapidly light is attenuated
•  = (ln I1- ln I2)/(z2 - z1)
Light is Attenuated More Rapidly in
Eutrophic Lakes
Eutrophic
7
B
100
Eutrophic
hic
tro
p
so
Oligotrop
hic
6
Olig
5
10
hic
otro
4
phic
3
1
op
otr
2
A
Me
s
Depth (m)
1
Light (% of incoming)
Me
0
Light (% of incoming)
0 20 40 60 80 100
Secchi Depth is Related to Extinction
30.0
Secchi depth (m)
20.0
10.0
8.0
7.0
6.0
5.0
4.0
Oligotrophic
Mesotrophic
3.0
Eutrophic
2.0
1.0
0.8
0.7
0
1
2
Extinction coefficient ()
4
Specific Wavelengths of Light
can be Attenuated Selectively
• Pure water transmits blue light most
efficiently
• Chlorophyll absorbs red and blue light most
efficiently
• Cyanobacteria have pigments that can use
green light
Transmittance (% m-1)
Relationship of Wavelength
and Adsorption of Pure Water
100
B
80
60
40
20
0
200
Infrared
Ultraviolet
300
400
500
Wavelength (nm)
600
700
800
Light transmission (%)
Lakes of Differing Trophic State
Transmit Light Differently
Light transmission (%)
100
101
102
Re
d
A
1
2
3
4
5
6
7
Blue
Green
Oligotrophic Lake
1
B
2
Mesotrophic Lake
ue
Bl
re
en
3
G
4
5
Re
d
Depth (m)
Depth (m)
10-1
6
Depth (m)
7
1
2
3
4
5
6
7
C
e
Blu
Eutrophic Lake
d
Re
G
en
re
Why are lakes the color they are,
fish the color they are, and fish
lures the color they are?
Hydrology and Physiography
of Groundwater and Wetland
Habitats
• Habitats and the hydrologic cycle
• Movement through soil and groundwater
• Chapter 4
Habitat
Time range
Distance range
Examples
Microhabitat
1s-1y
1 m - 1 mm
Fine particles of detritus, sand and clay
particles, surfaces of biotic and abiotic
solids in the environment.
Macrohabitat
1 d - 100 y
1 mm – 1000 m
Riffles and pools in streams, rivers, and
underground rivers. Logs, macrophyte
beds, pebbles - boulders, position on
lakeshore.
Local habitat
1 mo - 1000 y
1 mm - 100 km
Lake, regional aquifer, stream or riffle
reach, shallow lake bottom.
Watershed
1 y - 106 y
1 km - 10,000 km
Areas feeding small streams to the basins
of large rivers, including lakes, aquifers,
and streams within boundaries.
Landscape
10 y - 107 y
10 km - 10,000 km A mosaic of local habitats or watersheds.
Continent
10,000 - 109 y
> 10,000 km
A composite of large drainage
basins and aquifers
The Global Hydrologic Cycle
Evapotranspiration
Subsurface flow
Land
Precipitation
Percolation
Infiltration
Surface flow,
runoff
Ocean
Movement through Soil and
Groundwater, Groundwater Habitats
Water table
Perched water table
Heterogeneous aquifer
Soil
Vadose or
unsaturated
zone
Capillary
fringe
Unconsolidated
aquifer,
homogeneous
Confined
aquifer
Impermeable
layers
Groundwater Habitats
Limestone caves
Water table
Surface water
Artesian well
Wells
Groundwater
depletion
Permeable
layer, Gravel
Saltwater intrusion
Flow direction
Impermeable bedrock
Impermeable layer, Shale
Permeable layer
Confined aquifer
Sandstone
Flow direction
Atlas: US Geological Survey: www-atlas.usgs.go
Case Study: Ogallala
(High Plains) Aquifer
•
•
•
•
From Nebraska to Texas
Supplies 30% of irrigation water used in U.S.
Being used 10 times as fast as being replenished
Arkansas River below aquifer is mostly dry, above
almost always flows
• Eventually it will cost too much to pump irrigation
water up
http://web.mit.edu/12.000/www/m2012/finalwebsite/problem/groundwater.shtml
McGuire, V. L. (2001). Water-Level Change in the High Plains Aquifer,
1980 to 1999, US Geological Survey: 2.
Discharge (m 3/s + 0.01)
Discharge (m 3/s + 0.01)
10000
Arkansas at Syracuse
1000
100
10
1
0.1
0.01
0.001
1900
10000
1920
1940
1960
Year
1000
1980
2000
Arkansas at Dodge City
100
10
1
0.1
0.01
0.001
1900
1920
1940
1960
Year
1980
2000
Recent drought conditions in Kansas
Comparison of 2006 Stream flows to 1930-2005
Putnam, Perry, and Wolock. US Geological Survey Fact Sheet 2008–3034 April 2008
Stream discharge vs.
rainfall during past
droughts
Putnam, Perry, and Wolock. US Geological Survey Fact Sheet 2008–3034 April 2008
Hydrology and Physiography
Wetland Habitats
• Crucial to waterfowl, wildlife and plant life
• Provide vital ecosystem services such as
waste purification and flood control
• Most endangered aquatic habitat
• Chapter 5
(A) Wetlands, (B) Intermittent rivers, (C) Perennial rivers, (D) Intermittent Lakes, (E)
Perennial lakes
Salt marsh
Mangrove swamp
Freshwater marsh
Cypress swamp
Prairie potholes
Wetland Losses
•
•
•
•
70% of U.S. riparian wetlands lost
50% of prairie potholes gone
Half of Everglades drained
22 states have lost more than half of their
wetlands in the last 200 years
• Wetlands lost in other countries: Cameroon
(80%), New Zealand (90%), Australia
(95%), Thailand (96%), Vietnam (>99%)
Type
Description
Distribution
Geomorphology
Vegetation
Ecosystem
Importance
Tidal salt
marsh
A halophytic
grassland or dwarf
brushland on
riverine sediments
influenced by
tides or other
water fluctuations
Mid to high
latitude, on
intertidal
shores
worldwide
Form where
sediment input
exceeds land
subsidence in
regions with gentle
slopes
Salt-tolerant grasses
and
rushes/periphyton
Highly productive,
serves as nursery area
for many
commercially
important fish and
shellfish
Tidal
freshwater
marsh
Wetland close
enough to coast to
experience tidal
influence, but
above the reach of
oceanic saltwater
Mid to high
latitude, in
regions with
a broad
coastal plain
Area with adequate
rain or river flow,
with a flat gradient
near coastline
High plant diversity
including algae,
macrophytes, and
grasses
Highly productive,
many bird species;
often close to urban
communities and
susceptible to human
impacts
Mangrove
Tropical and
subtropical,
coastal, forested
wetland
25° north to
25° south
worldwide
Forms in areas
protected from
wave action
including bays,
estuaries, leeward
sides of islands, and
peninsulas
Halophytic trees,
shrubs and other
plants; generally
sparse understory
Exports organic
matter to coastal food
chains, physically
stabilizes coastlines;
may serve as a
nutrient sink
Type
Description
Distribution
Geomorphology
Vegetation
Ecosystem
Importance
Freshwater
marsh
A diverse group of
inland wetlands
dominated by grasses,
sedges, and other
emergent
hydrophytes; includes
important types such
as prairie potholes,
playas, and the
Everglades
Worldwide
Widely varied
Reeds such as Typha
and Phragmites; other
grasses such as
Panicum and Cladium,
sedges (e.g., Cyperus
and Carex); broadleaved monocots
(Sagittaria spp.); and
floating aquatic plants
Wildlife habitat, can
serve as nutrient sink
Northern
wetland
Bogs and peatlands
characterized by low
pH and peat
accumulation
Cold
temperate
climates of
high humidity,
generally in
Northern
Hemisphere
Forms in moist areas
where lakes become
filled in or where bay
vegetation spreads
and blankets; often a
terrestrial ecosystem
Acidophilic vegetation,
particularly mosses, but
also sedges, grasses,
and reeds
Low productivity
system
Deepwater
swamp
Fresh water most or
all of the season,
forested
Southeast
United States
Varied
Bald cypress-tupelo or
pond cypress- black
gum
Can be low nutrient or
high nutrient; can serve
as a nutrient sink
Riparian
wetland
Wetland adjacent to
rivers
Worldwide
In floodplains of
rivers in regions with
high water table
High diversity of
terrestrial plants
Can provide key
wildlife habitat and
productivity
particularly in more
arid regions; can act as
an essential nutrient
filter
Ecosystem Functions Based on
Hydrodynamic Characterization
Primary water
source
Climate
Geomorpological
aspects
Important quantitative
attributes
Functions that can relate to
ecological properties
Significance of function or
maintenance of characteristic
Precipitation
Humid
Poor drainage
Precipitation exceeds
evapotranspiration
during most times of
year so soils
waterlogged
Soil constantly waterlogged
leading to peat formation and
sediment anoxia
Low plant productivity related to
anoxic sediment keeping plants
from soil sources of nutrients,
plants rely upon nutrients in
precipitation only
Surface flow
from flooding
river
Mesichumid
Floods occur at
least annually
Frequency and height of
floods and position of
wetland an index of
connectivity to river
Overbank flow creates influx of
nutrients and moves sediments
(changes physical structure)
Allows continued high production
and high habitat heterogeneity.
Groundwater
influx
Mesic
Groundwater
springs and seeps
often at bottom of
slopes or stream
margins, some
sediments must be
permeable to allow
influx
Aquifer permanence,
yield of springs and
seeps dominates
hydrologic throughput
Groundwater supplies nutrients
and flushes habitat, habitat often
very stable
High plant production, stable plant
community
Classification of Subhabitats in Two Wetland Types
Managing Hydrology
of Everglades
• Everglades once had a sheet of water that flowed
across the lower 1/4th of Florida
• Was drained for agriculture and development
• Billions of dollars being spent on restoring more
natural flows
• 700 km of canals, 9 large pump stations, 18 gated
culverts, and 16 spillways make controlling
hydrology difficult
• Additional problems include nutrient pollution,
mercury pollution, and endangered species
C.W. McVoy, W.P. Said, J. Obeysekera, J.A. VanArman, T.W. Dreschel Landscapes and Hydrology of
the Predrainage Everglades University Press of Florida, Gainesville, FL (2011)
(http://www.evergladesplan.org/facts_info/maps.cfm).
(A) Wetlands, (B) Intermittent rivers, (C) Perennial rivers, (D) Intermittent Lakes, (E)
Perennial lakes
Physiography of
Flowing Water
• Characterization of streams
• Stream flow and geology
• Movements of materials by rivers and
streams
• Chapter 6
Characterization of Streams
•
•
•
•
•
Watershed (catchement) size
Stream order
Discharge
Flow regime
Vegetation
Strahler Ordering and Dendriditic,
Rectangular, and Parallel Drainage Basins
1
1
1
1
1
A
2 2
2
3
3
4
3
1
1
2
1
32
2
2 1
1
2
2
1
B
1
1
1
1
C
Length (km)
There are more small than large streams
A
101
100
10-1
Number
10-2
106
105
B
104
103
Total length (km)
102
C
104
103
102
0
1
2
3
4
5
Stream order
6
7
Discharge is not Velocity
•
•
•
•
Discharge is volume per unit time
Velocity is how fast water is going
Flow can mean discharge or velocity
Hydrographs are a plot of discharge over
time
101
101
A
B
0
100
10
10-1
10-1
10-2
10-2
3/25/1960
100
3/8/1971
1/27/1990
2/18/1982
C
-1
-1
10
10
10-2
10-2
10-3
10-3
3/29/1986
5/7/1990
8/15/1990 11/23/1990
5/7/1990
8/15/1990 11/23/1990
100
12/23/1988
8/11/1987
Discharge (m3 s-1)
Discharge
(m3 s-1 + 0.001)
Discharge (m3 s-1)
Contrasting Hydrographs, Niobrara,
Kings Creek, Slatey River
9/19/1991
D
1/27/1990
5/7/1990
5
10
E
104
103
102
7/4/19968/13/19969/22/199611/1/199612/11/1996
Date
A
The Effect of Dams on Missouri River Flow
1000000
A
100000
10000
1930
1945
1960
1975
1990
Discharge (m3 d-1)
800000
600000
B
400000
200000
0
1/1/1930
4/2/1930
800000
600000
7/2/1930
12/31/1930
10/1/1930
C
400000
200000
0
1/1/1980
7/1/1980
4/1/1980
12/31/1980
9/30/1980
Date
Method of Classifying Streams by
Discharge Patterns (Poff and Ward)
Drying frequency
Often
Flood and discharge
frequency/predictability
Rare-frequent
Harsh intermittent
Strong
Low
Frequent
Intermittent flashy
Strong
Low
Infrequent
Intermittent runoff
Strong
Rare
Frequent unpredictable floods,
low discharge predictability
Perennial flashy
Strong
Rare
Frequent predictable floods, low
discharge predictability
Infrequent floods, low discharge
predictability
Infrequent floods, high
discharge predictability
Infrequent predictable floods,
high discharge predictability
Infrequent predictable floods,
high discharge predictability
Snow and rain
Strong-intermediate
Perennial runoff
Strong- intermediate
Mesic groundwater
Weak
Winter rain
Seasonally strong
Snowmelt
Seasonally strong
Rare
Rare
Rare
Rare
Stream type
Effect on biota
Rainfall, Discharge
B
Undisturbed
Urbanized
Discharge
Floods
Discharge
Rain
A
Time (h)
Watershed Alteration changes
Flood Characteristics
Discharge (m3 s-1)
8
7
6
5
4
1931-1960 Pre-urbanization
1961-1991 Post-urbanization
3
2
102
8
7
6
5
4
3
3 4 5 67
100
2
3
4 5 6 78
101
Recurrence Interval (y)
2
3
4 5
Meandering, Riffles, and Pools
Pool
Riffle
a
Side View
Pool
a’
Pool
Riffle
Pool
Downstream
Top View
Thalweg,
fastest
velocity
Riffle
b
Riffle
a’
b’
Pool
a
a’
a
Velocity contour,
Current rotation
cross sectional at bend, at bend
maximum to outside
b’
b
Velocity contour,
cross sectional at crossover,
maximum in center
Riffles and Pools
Direction of
flow
Riffle
Pool
Water surface
Porous bedrock
Gravel
Fine sediments
Heterogeneity in the
Flood Plain
An Example of Channel Modification
from Oregon
A
B
1
2
0
0
0
1
1
0
0
0
1
0
0
0
0
9
0
0
0
8
0
0
0
7
0
0
0
6
0
0
0
5
0
0
0
4
0
0
0
Snagsdtremoved(numbr)
3
0
0
0
2
0
0
0
1
0
0
0
0
1
8
7
0
1
8
8
0
1
8
9
0
1
9
0
0
1
9
1
0
1
9
2
0
1
9
3
0
1
9
4
0
1
9
5
0
Y
e
a
r
Materials Dissolved in River Water
Attribute
Natural
concentration
13.4
Pollution
% increase
Ca2+
Current
concentration
14.7
1.3
9%
Mg2+
3.7
3.4
0.3
8%
Na+
7.2
5.2
1.3
28%
K+
1.4
1.3
0.1
7%
Cl-
8.3
5.8
2.5
30%
SO42-
11.5
6.6
4.9
43%
HCO3-
53.0
52.0
1.0
2%
SiO2
10.4
10.4
0.0
0%
110.1
99.6
10.5
11%
21.5
14.5
7.0
32%
2.0
1.0
1.0
50%
Total dissolved solids
Dissolved nitrogen
Dissolved phosphorus
Chloride concentration (mg L-1)
Movement of Dissolved
Materials in Streams
8
0m
6
100 m
4
2
0
0
10
20
30
40
50
Time (min)
60
70
80
90
WaterVlociy(ms -1) Clay
Silt
FineSad
CoarseSnd
Gravel,Pbs
RuBboluelder
Movement of Solids in Streams as a Function of Velocity
1
0
0
0
E
r
o
s
i
o
n
1
0
0
1
0 T
r
a
n
s
p
o
r
t
1
S
e
d
i
m
e
n
t
a
t
i
o
n
0
3
2
1
0
1
2
3
1
0
1
0
1
0
1
0
1
0
1
0
1
0
S
i
z
e
(
m
m
)
Movement of Solids in Streams as a
Function of Size
2
5.82 m 3 s -1
25.6 m 3 s -1
Percent by Weight
101
7
6
5
4
3
2
100
6
5
4
3
2
1
10-1.0
2
3
4 5 5 6
100.0
2
3
Sediment Size (mm)
4 5 6 7
101.0
2
Scale and
Rivers
5
1
0
A
4
1
0
3
1
0
2
1
0
1
1
0
Spatilsce(m)
0
1
0
1
1
0
2
1
0
3
1
0
4
1
0
2
1
0
1
2
3
4
5
6
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
5
1
0
B
4
1
0
Ecosystem engineers
(beavers, alligators,
hippopotamus)
3
1
0
2
1
0
1
1
0
Spatilsce(m)
0
1
0
1
1
0
2
1
0
Detritus
(coarse and fine
organic material)
3
1
0
4
1
0
2
1
0
1
2
3
4
5
6
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
T
e
m
p
o
r
a
l
s
c
a
l
e
o
f
c
h
a
n
g
e
(
y
)
Physiography of Lakes
and Reservoirs:
•
•
•
•
Formation: Geological processes
Lake habitats and morphometry
Stratification
Water movement and currents in lakes
• Chapter 7
Formation: Geological
Processes
• Most lakes are small, a few lakes are huge
• Lakes most common in glaciated regions
• Global distribution of lakes
Ways that Lakes Form
Lake type
Formation process
Essential characteristics and
examples
Basin formed by movement of earth’s crust
Graben: a block slips down between two others,
Horst: diagonal slippage.
Formed when ice left from retreating glacier is
buried in till (solid material deposited by
glacier) and then melts.
Glacial activity deposits a dam of rock and
debris.
Can be very old and very deep.
Lake Baikal, Asia; Lake
Tanganyika, Africa
Small lakes/ wetlands, prairie
pothole region in Alberta and North
and South Dakota.
Narrow, fill valley
Earthslide
Movement of earth dams a stream or river.
Similar to reservoirs, Quake Lake,
Montana
Volcanic –
Caldera
Volcanic explosion causes hole that is filled with
water.
Often round and deep, Crater Lake,
Oregon
Dissolution
Lake
Limestone dissolves and lake forms.
Small, steep sides
Oxbow
River bend pinches off, leaves lake behind.
Shallow, narrow, may be seasonally
flooded
Tectonic
Pothole or
Kettle
Moraine
Tectonic
Glacial
Total surface area (10,000 km 2)
Numbers and Sizes of Lakes by Formation Type
40
30
20
10
0
Tectonic
10
102
100
Glacial
106
Glacial
104
20
10
102
0
100
6
Tectonic
4
40
30
106
Fluvial
106
4
104
2
102
0
100
Surface area range (km 2)
Fluvial
(A) Wetlands, (B) Intermittent rivers, (C) Perennial rivers, (D) Intermittent Lakes, (E)
Perennial lakes
Lake Habitats and
Morphometry
• Volume = area * depth
• Retention time = volume / discharge
• Shoreline development index
L
Dl 
2  A0
Bathymetric Maps
Stratification
• Layering based on differences in density
(temperature or salinity)
• Stratification alters biogeochemistry and
ecology
• Lake with all same temperature called
isothermal
• Three layers of lake that is thermally
stratified
A Thermally Stratified Lake
Temperature (0C)
0
0
2
4
6
8
10
12
14
16
Epilimnion
Depth (m)
5
Metalimnion
(thermocline)
10
15
Hypolimnion
20
25
18
Seasonal Stratification in a Temperate Lake
Even a Hurricane can’t Break Stratification
Temperature (oC)
0
6
8
10
12
14
16
18
3
Depth (m)
5
8
10
13
15
After hurricane
Before hurricane
20
Stratification Terminology
•
•
•
•
Monomictic- mixes once a year
Amictic- never mixes (e.g. saline lakes)
Polymictic- mixes several times a year
Dimictic- mixes twice a year
Water Movement and
Currents in Lakes
•
•
•
•
Wind
Fetch
Langmuir Cells
Seiches
Fetch
A
B
Wind direction
Fetch
Fetch
Wind direction
C
5
4
3
Maximuwvehgt(m)
2
1
0
0 1
02
03
04
05
0
F
e
t
c
h
(
k
m
)
Langmuir streaks at Quake Lake
Montana
American Society of Limnology and Oceanography image gallery
Seiches and Entrainment
Wind stops
A
Epilimnion
D
Hypolimnion
Hypolimnion begins to rock
Wind
E
B
Hypolimnion rocks to opposite extreme,
then returns to original position
Wind
C
F
Mixing zones
Seiche continues but slowly dissipates