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Health and the Global Water Supply. Dennis P. Lettenmaier Department of Civil and Environmental Engineering University of Washington Seattle, WA for presentation at Lecture Series on Global Health Issues confronting the World Community University of Washington Extension Service
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Health and the Global Water Supply Dennis P. Lettenmaier Department of Civil and Environmental Engineering University of Washington Seattle, WA for presentation at Lecture Series on Global Health Issues confronting the World Community University of Washington Extension Service November 8, 2004
Outline of this talk • The global (and regional) water and energy cycles • Human needs for potable water • Water and food • Water development • Water and climate • Water quality and health • Conclusions – the path forward
Column water balance (e.g. of a region) Source: Kooiti Masuda, 2002
Water balance of major global rivers Source: Kooiti Masuda, 2002
Water balance of major global rivers Source: Kooiti Masuda, 2002
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)
Blue and Green water (after Falkenmark) • Green Water is rainfall that is stored in the soil and available to plants. Globally, it makes up some 65 per cent of fresh water resources. It is the basis of rain-fed farming and all terrestrial ecosystems. • Runoff, stream base flow and groundwater constitute blue water. Green water may be used only in situ: whereas blue water may be transported and used elsewhere – for irrigation, urban and industrial use, and as environmental flow in streams. Courtesy Wageningen University
Figure courtesy of world soil information, Wageningen University
Figure courtesy of world soil information, Wageningen University
Notes • Rain-fed agriculture contributes most of the world’s farm production: 95 per cent in Sub-Saharan Africa where it makes use of only 15-30 per cent of rainfall, the rest is lost, mostly as destructive runoff; • The partitioning of rainwater is a dynamic process (governed by rainfall intensity, terrain, land cover and soil) that may be controlled by management of land cover, micro topography and soil conditions; • Soils process several times more water than they retain; while soil erosion by runoff and bank erosion by peak flows contribute nearly all the sediment load of streams, leading to the siltation of reservoirs and water courses. This means that management of green water is also management of blue water; • Finally, agricultural demand for water is in competition or, even, conflict with the needs of industry, urban populations and the environment. Courtesy Wageningen University
Global Runoff & Water use (http://hydro.iis.u-tokyo.ac.jp/GW/result)
50< 15~20 30~50 1~5 5~10 10~15 20~30 An Adaptation Strategy to Cope with Scarcity? “Virtual Water” flow in 2000 (cereals only) 78.5 USSR Middle East Western Europe 33.5 NorthAmerica East &South East Asia 38.8 57.5 North West Africa South Asia Caribbean Central America West Africa 36.4 South America 46.2 Oceania Importer based, over 5 km3/y km3/y (Based on Statistics from FAO etc., for 2000) (Oki, et. al, 2002, IHE-UNESCO)
Global Reservoir Database Location (lat./lon.), Storage capacity, Area of water surface, Purpose of dam, Year of construction, … 13,382dams,
Nasser Chad (2) (1) Tana (3) (4) Turkana Kainji Victoria Volta dV(km3) Precipitation (mm) Malawi Tanganyka Mweru Cabora-Bassa Kariba (1) Chad Variation of Reservoir Storage (estimated by RS, 1992-2000) (2) Nasser (4) Volta (3) Turkana
Global Water System Project IGBP – IHDP – WCRP - Diversitas
Global Water System Project IGBP – IHDP – WCRP - Diversitas Human modification of hydrological systems
Reservoir construction has slowed. All reservoirs larger than 0.1 km3
-150 -120 -90 -60 -30 0 30 60 90 120 150 90 90 1 60 60 5 4 6 2 7 30 30 8 9 0 0 3 -30 -30 -60 -60 -90 -90 -150 -120 -90 -60 -30 0 30 60 90 120 150 1 MacKenzie 2 Mississippi 3 Amazon 4 Severnaya Dvina 5 Yenisei 6 Amur 7 Yellow 8 Xi 9 Mekong Global Climate Change Selected Basins
Selected Basins Basin Characteristics
40 Amazon Amur Mackenzie 30 20 10 0 -10 -20 -30 -40 40 Mekong Mississippi Severnaya Dvina 30 20 Change in precipitation (%) 10 0 -10 -20 -30 -40 40 Xi Yellow Yenisei 30 20 10 0 -10 -20 -30 -40 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8 9 Change in temperature (C) GFDL_CGCM HCCPR-CM2 HCCPR-CM3 MPI-ECHAM4 CCCMA-CGCM1 CCSR-CGCM CSIRO-CGCM DOE-PCM3 2025 2045 2095 GCM Predicted Climate Change Change in precipitation and temperature for selected basins
300 Amazon Amur MacKenzie 200 mm 100 0 50 50 50 25 25 25 % change 0 0 0 -25 -25 -25 300 -50 -50 -50 Mekong Mississippi Severnaya Dvina 200 mm 100 0 50 50 50 25 25 25 % change 0 0 0 -25 -25 -25 300 -50 -50 -50 Xi Yellow Yenisei 200 mm 100 50 0 50 50 25 25 25 % change 0 0 0 -25 -25 -25 -50 -50 -50 J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D HCCPR-CM2 HCCPR-CM3 MPI-ECHAM4 DOE-PCM3 Predicted Precipitation Changes 2045
40 Amazon Amur MacKenzie 20 °C 0 -20 8 -40 8 8 4 4 4 °C 0 0 0 -4 40 -4 -4 Mekong Mississippi Severnaya Dvina 20 °C 0 -20 -40 8 8 8 4 4 4 °C 0 0 0 40 -4 -4 -4 Yellow Xi Yenisei 20 °C 0 -20 -40 8 8 8 4 4 4 °C 0 0 0 -4 -4 -4 J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D HCCPR-CM2 HCCPR-CM3 MPI-ECHAM4 DOE-PCM3 Predicted Temperature Changes 2045
300000 25000 30000 Amazon Amur MacKenzie 20000 m3/s 200000 20000 15000 10000 100000 10000 5000 0 0 0 40000 50000 20000 Mekong Mississippi Severnaya Dvina 40000 30000 15000 m3/s 30000 10000 20000 20000 10000 5000 10000 0 0 0 15000 4000 100000 Xi Yellow Yenisei 3000 75000 10000 m3/s 2000 50000 5000 1000 25000 0 0 0 J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D Baseline HCCPR-CM2 HCCPR-CM3 MPI-ECHAM4 DOE-PCM3 Simulated Streamflow 2025
300000 25000 30000 MacKenzie Amazon Amur 20000 200000 20000 m3/s 15000 10000 100000 10000 5000 0 0 0 40000 50000 20000 Mekong Mississippi Severnaya Dvina 40000 15000 30000 30000 m3/s 20000 10000 20000 10000 5000 10000 0 0 0 15000 4000 100000 Xi Yellow Yenisei 3000 75000 10000 2000 50000 m3/s 5000 1000 25000 0 0 0 J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D Baseline HCCPR-CM2 HCCPR-CM3 MPI-ECHAM4 DOE-PCM3 Simulated Streamflow 2045
GCM grid mesh over western U.S. (NCAR/DOE Parallel Climate Model at ~ 2.8 degrees lat-long) Western U.S. regional study
BAU 3-run average historical (1950-99) control (2000-2048) PCM Business-as-Usual scenarios Columbia River Basin (Basin Averages)
PCM Business-As-Usual Mean Monthly Hydrographs Columbia River Basin @ The Dalles, OR 1 month 12 1 month 12
Annual Releases to the Lower Basin target release
Annual Releases to Mexico target release
Global Water System Project IGBP – IHDP – WCRP - Diversitas Global assessment of water scarcity Crisis of Global Water Resources in 2025: Climate or Population Growth Vörösmarty, 2000