Comments on the role of a surface water mission in the context of global water

issuesDennis P. Lettenmaier

Department of Civil and Environmental EngineeringUniversity of Washington

Seattle, WA

CNES/NASA Surface Water Working Group Meeting

Toulouse

November 16, 2004

• 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)

Table courtesy Peter Gleick

Table courtesy Peter Gleick

Figure courtesy of world soil information, Wageningen University

Figure courtesy of world soil information, Wageningen University

(Oki, et. al, 2002, IHE-UNESCO)

CaribbeanCaribbean

NorthNorth AmericaAmerica

Central Central AmericaAmerica

South South AmericaAmerica

WestWest

AfricaAfrica

OceaniaOceania

East &East &South East AsiaSouth East Asia

SouthSouth

AsiaAsia

USSRUSSR

North WestNorth WestAfricaAfrica

WesternWesternEuropeEurope

MiddleMiddle

EastEast

1~5 5~10 10~15 15~20 20~30 30~50 50<

Importer based, over 5 km3/y

km3/y

(Based on Statistics from FAO etc., for 2000)

78.5

33.5

46.2

57.538.8

36.4

An Adaptation Strategy to Cope with Scarcity? “Virtual Water” flow in 2000 (cereals only)

Global Reservoir DatabaseGlobal Reservoir DatabaseLocation (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 modificationof hydrological systems

Regulated Flow

Historic Naturalized Flow

Estimated Range of Naturalized FlowWith 2040’s Warming

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.

0

100

200

300

400

500

600

700

800

Up to1900

1901-1910

1911-1920

1921-1930

1931-1940

1941-1950

1951-1960

1961-1970

1971-1980

1981-1990

1990-1998

Nu

mb

er

of

Re

se

rvo

irs

.

Australia/New Zealand

Africa

Asia

Europe

Central and South America

North America

Reservoir construction has slowed.

All reservoirs larger than 0.1 km3

Visual from Palmieri, NAS Sackler symposium, 2004

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.

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.

Gleick 2001

The link between water use and economic growth can be broken

0

1000

2000

3000

4000

5000

6000

7000

8000

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

$199

6 U

.S. G

NP

0

100

200

300

400

500

600

700

800

900

1000

Wat

er W

ithd

raw

als

(km3 /y

r)

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(and we are changing the structure of our economy…)

•Agricultural water use can drop and yields can increase with better irrigation technology.

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!)