The role of technology in global water
problems: The proposed Water Elevation
Recovery mission
Dennis P. Lettenmaier
Department of Civil and Environmental Engineering
University of Washington
presented at
Water as a Source of Conflict and Cooperation:
Exploring the Potential
February 26-27, 2005
Tufts University
Medford, Massachusetts
Outline
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Basic facts on global water usage
Reservoir Impoundments
TransBoundary Issues
How a surface water mission would help
A thumbnail sketch of global water issues
 Approximately 25,000 people die each year due to floods
 Drought losses globally have exceeded $300B over the last decade
 More than 1.2 billion have inadequate drinking water (poor quality,
insufficient quantity)
 Twice that many (2.5 billion) lack adequate sanitation facilities.
 Approximately 10% of the annual discharge of the world’s rivers is
used consumptively, and several major continental rivers (e.g.,
Colorado, Nile, Yellow) are dry for at least part of the year
 The quality of many of the world’s rivers has been seriously
degraded by a combination of pollution, land cover change, dams,
and other factors
 Many, if not most, of these problems are not amenable to
technological solutions – but some are
 One such example is the acquisition of data about river discharge,
and the storage of water in reservoirs, lakes, and wetlands
Why do we care about streamflow?
• Rivers are the earth’s arteries
• Rivers are a primary source of water for human
consumption, food production, transportation,
and many other uses
• Riparian corridors (including wetlands) are
extraordinarily productive and diverse
biologically
• Much of the world’s population lives in flood
plains
• Rivers also pose major hazards to human life
and well being (due to both floods and droughts)
• Domestic consumptive use (U.S.) is ~200-250
liters/day
• Compare with drinking water requirement (about
5 l/day). U.S. domestic consumption has
declined slightly over the last two decades.
Much of difference between potable water
requirement and use is sanitation, laundry, etc.
• Industrial requirement in developed world is of
same order as domestic
• Total water withdrawals are about 6000 km3/yr
• Compare with global (land) precip ~150,000
km3/yr (or global runoff ~0.4 x runoff)
The Global Picture
● Water resource issues will have large effects on many
of the world’s major decisions in the next 50 years.
● 1 billion people live on less than $1/day.
● More than 1.2 billion have inadequate drinking water
(poor quality, insufficient quantity, but still priced
beyond the means of the poorest), and twice that
many (2.5 billion) lack sanitation facilities.
● Poorly handled: could result in wars and will result
in premature deaths, poor quality of life for many,
and widespread degradation of aquatic ecosystems.
● Well handled: opportunities for scientific and political
creativity, international collaboration, promoting
cooperation rather than discord.
Widespread efficiency improvements
are possible, in all sectors
• 1930s: 200 tons of water per ton of steel
• 1980s: 20-30 tons of water per ton of steel
• 2002: 2-3 tons of water per ton of steel
• Agricultural water use can drop and yields can
increase with better irrigation technology.
• Essentially, industrialized nations have improved
their water usage, but what about developing
nations?
• And population growth is a water management
problem… next 3 slides
Unmet Basic Human Needs for Water
• 1.1 billion people lack access to adequate
drinking water (mostly in Africa and Asia).
• 2.4 billion people lack access to adequate
sanitation services.
• 2.2 to 5 million die annually from
preventable water-related diseases.
– What are the implications for
global water management and
assessment?
For 2025, Relative to 1985
• Ability to globally forecast
freshwater availability is critical for
population sustainability.
• Water use changes due to
population are more significant than
climate change impacts.
• Predictions also demonstrate the
complications to simple runoff
predictions that ignore human water
usage (e.g., irrigation).
Vörösmarty, C.J., P. Green, J. Salisbury, and R.B. Lammers, Global water resources: Vulnerability from climate change and
population growth, Science, 289, 284-288, 2000.
Global Reservoir Database
Location (lat./lon.), Storage capacity, Area of water surface,
Purpose of dam, Year of construction, …
13,382dams,
Global Water System Project
IGBP – IHDP – WCRP - Diversitas
Global Water System Project
IGBP – IHDP – WCRP - Diversitas
Human modification
of hydrological systems
Historic Naturalized Flow
Estimated Range of
Naturalized Flow
With 2040’s Warming
Regulated Flow
Figure 1: mean seasonal hydrographs of the Columbia River prior to (blue) and after the completion of reservoirs
that now have storage capacity equal to about one-third of the river’s mean annual flow (red), and the projected
range of impacts on naturalized flows predicted to result from a range of global warming scenarios over the next
century. Climate change scenarios IPCC Data and Distribution Center, hydrologic simulations courtesy of A.
Hamlet, University of Washington.
Reservoir construction has slowed.
800
.
700
Number of Reservoirs
600
500
Australia/New Zealand
Africa
Asia
Europe
Central and South America
North America
400
300
200
100
0
Up to 1901- 1911- 1921- 1931- 1941- 1951- 1961- 1971- 1981- 19901900 1910 1920 1930 1940 1950 1960 1970 1980 1990 1998
All reservoirs larger than 0.1 km3
Case study – Ganges – Brahmaputra River flood forecasting
Source: Jorgensen and Host-Madsen, 1997
Brahmaputra River 25-day lead forecasts using
experimental ECMWF long-lead precipitation forecasts
Visual courtesy Tony Hollingsworth, ECMWF
• Question: why not just use discharge at
upstream gauges in India?
• Answer: Because India won’t release the
data (at least in anything close to realtime)
Flooding Issues
• Flooding imposes clear dangers,
but the lack of water heights and
inundation mapping during the
passage of the flood wave limit
important hydraulic modeling that
would otherwise predict the zones
of impact.
• Essentially, can we predict flooding
hazards which could be used to
understand the consequences of
land use, land cover, and climatic
changes for a number of globallysignificant, inhabited floodplains?
Prague
Estimated Costs: $1.9 Billion
Over 100 dead in Europe, alone
Black Sea
Kentucky
China
These are the floods
from 2002, alone!
India
From the standpoint of global water issues,
what would be the impact of the proposed
WatER mission?
• Freely available data on water storage for water
bodies larger than ~1 km
• Capability to produce river discharge estimates
for many rivers with width > ~50-100 m
• Major implications for the ability to predict floods
and droughts globally
• Elimination of “competive advantage” of
upstream countries in trans-boundary rivers
• Implications for global markets (especially food)
Possible role and implications of a
global surface water mission
• Free and open exchange of global
hydrologic data (which presently does not
exist)
• Understanding how reservoirs are
operated (presently there is no coherent
data base for reservoir storage)
• Water and human health (2 billion
incidences of waterborne diseases per
year globally!)