Transcript Intro to Planetary Management

U6115: Climate & Water
Friday, June 20 2003
“Eagles may soar, but
weasels don't get
sucked into jet
engines”
“Hard work pays off in
the future. Laziness
pays off now”
Today: Water/Hydrology
•Systems and Cycles
• Flux, Source/Sink, Residence time, Feedback
mechanisms…
• Hydrological System
• Specific reservoirs, Residence time, variability
• Water for the world
• An introduction to management issues
Cycle Approach
 Some Definitions
 Transport and transformation processes within definite reservoirs: Carbon,
Rock, Water Cycles
 Reservoir: (box, compartment: M in mass units or moles) An amount of
material defined by certain physical, chemical, or biological characteristics
that can be considered homogeneous
– O2 in the atmosphere
– Carbon in living organic matter in the Ocean
– Water in the Ocean
 Flux: (F) The amount of material transferred from one reservoir to another
per unit time (M/s or M/s.L2)
– The rate of evaporation of water from the surface Ocean
– The rate of deposition of inorganic carbon (carbonates on marine
sediments
 Source: (I or Q) A flux of material into a reservoir
 Sink: (O or S) A flux of material out of a reservoir
More Definitions…
 Budget: A balance sheet of all sources and sinks of a reservoir.
If sources and sinks balance each other and do not change with
time, the reservoir is in steady-state (M does not change with
time). If steady-state prevails, then a flux that is unknown can
be estimated by its difference from the other fluxes.
for a control volume this means: dM/dt = I'-O'
 Turnover time: The ratio of the content (M) of the reservoir to
the sum of its sinks (O) or sources (I). The time it will take to
empty the reservoir if there aren’t any sources. It is also a
measure of the average time an atom/molecule spends in the
reservoir. Or:
0 = M/O (or M/I)
 Cycle: A system consisting of two or more connected
reservoir, where a large part of the material (energy) is
transferred through the system in a cyclic fashion
The Water (Hydrologic) Cycle
A Mighty Exchange
Atmosphere (0.0155)
Transport (0.036)
Evaporation
(0.071)
Precipitation
(0.107)
Precipitation
(0.398)
Evaporation
(0.434)
Runoff
(0.036)
Ice (43.4)
Lakes & Rivers (0.13)
Groundwater (15.3)
All reservoir values are in 106
km3 while all fluxes are in 106
km3/yr
Adapted from Berner & Berner (The
Global Water Cycle; Prentice Hall, 1987)
Oceans (1400)
The Water Cycle (in detail)
The volume (M) of water at the surface of the Earth is
enormous: 1.37 109 km3! (total reservoir) – The Oceans cover
71% of the Earth’s surface (29% for the continent masses above
sea level)
Reservoir
Biosphere
Volume (km3)
0.6 103
Rivers
Atmosphere
Lakes
Groundwater
Glacial and other land ice (?)
Oceanic water and sea ice
Total
% Total
0.00004
1.7 103
13 103
125 103
9500 103
29000 103
0.0001
0.001
0.01
0.68
2.05
1,370,000 103
97.25
1,408,640 103
Adapted from Berner & Berner (The Global Water Cycle; Prentice Hall, 1987)
100
Fluxes (F in 103 km3/yr)
 Of total yearly evaporation, 84% evaporates from the Oceans
and 16% from surface of continents.
 However, return to Earth via precipitation: 75% falls directly
on the Oceans and 25% on the continents.
 During the year, the atmosphere transports 9% of Oceans’
evaporation to the continents!
 This water is returned via surface streams and as groundwater
Errors!
 Precipitation and
evaporation are difficult
to measure precisely
over the oceans. They
are mostly estimated
from models and satellite
data.
 Groundwater reservoir
estimates bear a
inherent error in the
fact that they are
indirectly determined.
 Soil moisture and
evapotranspiration rates
depend on indirect
measurements and
average soil quality and
global/regional
respiration rates
Residence Time
(years – months – weeks)
The simplified residence time  turnover time
The time it would take to empty a reservoir if the sink (O)
remained constant while the sources were zero

0
= M/O (or M/I)
M = 0O
Residence time of water in the atmosphere
M = ?; S = ?; 0 = ?
M = 13 103 km3
S = 297(O) + 99(C) 103 km3/yr = 396 103 km3/yr

0
= 0.033 yr = 12 days!
Replacement ~30 times/year
Residence Time
(years – months – weeks)
The simplified residence time  turnover time
The time it would take to empty a reservoir if the sink
(O) remained constant while the sources were zero
0 = M/O (or M/I)
M = 0 O
Residence time of water in the atmosphere
M = ?; S = ?; 0 = ?
M = 1,370,000 103 km3
S = 334 103 km3/yr (evaporation)
0 = M/S = 4102 yrs!
2) Continental Distribution
Continental Mass Balance
• quantitative description  applying the principle of conservation of mass
• for any given control volume at steady state:
dV/dt = 0 = p + rsi + rgi - rso - rgo - et = 0 (all averaged)
• For continents as control volume this can be written as
dV/dt = p - rso - et = 0 (all averaged)
on average this means: p = rso + et
the water budget for all land areas of
the world is:
p=800mm, rs = 310mm, and et =
490mm
the global runoff ration (rs/p) is
~39% there are lots of local and
regional variations.
2) Continental Distribution
System Approach…
Feedback: All closed and open systems respond to inputs
and have outputs. A feedback is a specific output that
serves as an input to the system.
Negative Feedback (stabilizing): The system’s response is
in the opposite direction as that of the output. CLOUDS!
System Approach…
Positive Feedback (destabilizing): The system’s
response is in the same direction as that of the output.
Number of bacteria
"Bacteria in a bottle"
1.4E+18
1.2E+18
1.0E+18
8.0E+17
6.0E+17
4.0E+17
Bottle half full
2.0E+17
0.0E+00
0
10
20
30
40
Time (minutes)
50
59 min
60
System Approach…
Positive Feedback (destabilizing):
CLOUDS!
Source, use &
disposition of
water in the
US, (1990)
Modified from http://
water.usgs.gov/watuse/
wuto.html
Surface waters
BRF
Watershed, catchment, drainage basin
“A catchment (watershed, drainage basin) is an area of land
in which water flowing across the land surface drains into a
particular stream or river and ultimately flows through a
single point or outlet on that stream or river”
Measurement techniques
=> precipitation
=> evapotranspiration
Measurement techniques
 flow depth (stage)
 discharge
BRF
Colorado River
hydrograph
Questions:
• When does discharge peak and
why?
• The hydrographs were taken at
different locations of the river,
what is the difference in the
hydrographs and why is there
one?
Colorado River
hydrograph
• Hydrographs are
variable between years
• Discharge often peaks
in late winter or
spring, snowmelt
• Reservoirs smooth out
extremes
Canada del Oro hydrograph
 extended periods with no discharge at all!
http://water.usgs.gov
Groundwater
Groundwater flow is
controlled by
– differences in water table
(hydraulic head)
– hydraulic conductivity
(relation between specific
discharge – Vol/t – and
hydraulic gradient)
– Hydraulic conductivity
depends on both the nature
of the fluid (viscosity) and
the porosity of the material
Hornberger et al., 1998
Measurement techniques
 Hydraulic head, conductivity
Physical flow model
Water: Counting every drop…
“Access to safe water is a fundamental human need and,
therefore, a basic human right.
Contaminated water jeopardizes both the physical and
social health of all people. It is an affront to human dignity”
Kofi Annan – UN Secretary-General on World Water Day
“Making prediction is very difficult,
especially about the future” – Casey Stengel
Water scenarios: Projected and actual global withdrawals.
From Gleick (2000): The World’s Water, 2000-2001
“North America’s abundant water resources
represent 14% of the global renewable fresh water”
Annual Freshwater Withdrawals
Per Capita (m3/yr)
2000
1600
1200
Canada
Mexico
United States
North America
World
800
400
or
ld
W
Am
er
ica
s
or
th
N
U
ni
te
d
St
at
e
ico
M
ex
C
an
a
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0
From Commission for Environmental
Cooperation (2000): The North
Water: Our U.S. Budget
Main loss (66%)
Stream Flow (32%)
Humans (~2%)
“North America’s abundant water resources
represent 14% of the global renewable fresh water”
in many areas of the US more water is withdrawn than is renewed
*
global warming
*
floods, hurricanes
*
groundwater and surface water contamination
South Texas
Coastal Bend:
A Case Study
3 Major Basins providing
water to Corpus
Colorado
Nueces
Lavaca
“Making predictions…”
Aquifer
recharge
proposed
Mary
Rhodes
pipeline
Pass through needs
for estuaries
Water scenario: Regional
management model
The case for water quality!
“If I die, I will die, but I will not fetch water from another man’s house” –
Bangladeshi villager
The case for water quality!
“If I die, I will die, but I will not fetch water from another man’s house” –
Bangladeshi villager
The case for water quality!
“If I die, I will die, but I will not fetch water from another man’s house” –
Bangladeshi villager
• Arsenic is conservative (high during
drought intensive periods!)
• Desalination  expensive and exacerbate
hypersalinity of lagoons
• Groundwater  Bangladesh anyone?
Concluding Thought
•And after you’ve “heard” this story of great
misfortunes, you will no doubt dine well, blaming the
author for your own insensitivity, accusing him of wild
exaggeration and flights of fancy. But rest assured: this
tragedy is not a fiction. All is true”
•Honoré de Balzac