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RIVER INPUTS TO OCEANS AND GLOBAL CHANGE Michel Meybeck Sisyphe, CNRS/Université Paris 6 Charles Vörösmarty, Water Analy

RIVER INPUTS TO OCEANS AND GLOBAL CHANGE Michel Meybeck Sisyphe, CNRS/Université Paris 6 Charles Vörösmarty, Water Analysis Group, Univ. New Hampshire. Why and How to establish river fluxes at global scales ? Where are the highest fluxes ?

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RIVER INPUTS TO OCEANS AND GLOBAL CHANGE Michel Meybeck Sisyphe, CNRS/Université Paris 6 Charles Vörösmarty, Water Analy

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  1. RIVER INPUTS TO OCEANS AND GLOBAL CHANGEMichel Meybeck Sisyphe, CNRS/Université Paris 6Charles Vörösmarty, Water Analysis Group, Univ. New Hampshire • Why and How to establish river fluxes at global scales ? • Where are the highest fluxes ? • When fluxes reacted or will react to global change ? • Who is responsible for riverine changes ? • Future evolution evolutions and new track ASLO-HAWAI 2004

  2. WHY SET UP RIVER FLUXES AT GLOBAL SCALES ? QUESTIONS PRECURSORS • Global river we thering rates Clarke 1924, Alekin 1950s, Livingstone 1963 • Origins of Sedimentary rocks Garrels and Mackenzie, 1971 • Biogeochemical cycles: carbon, Garrels, Mackenzie, Hunt, 1973 Nitrogen, Sulfur, silica • Global denudation Fourier 1960, Janssen and Painter, 1974 • Coastal geomorphology/Sedimentology Milliman 70’s • Pollutants Inputs to oceans Goldberg 70’s • Earth System and Global change IGPB 80’s ASLO-HAWAI 2004

  3. HOW TO CONSTRUCT GLOBAL RIVER FLUXES ? • Some problems encountered • How to deal with extreme variations of conc. & yields over 2 or 3 orders of magnitude (e.g. hot spots ?) • Amazon in or out ? (15% of water fluxes) • Are yields influenced by sized (e.g. Sediment Milliman & Syvitski) • How to filter human impacts for assessing past natural fluxes • How to take into account all human impacts for future evolution (e.g. sources vs sinks; scenarios) • How to identify key controls/drivers in both natural and present day conditions • Space resolution ? Gobal to local river input • Time resolution. Average fluxes vs seas onal

  4. DEVELOPING TOOLS • River data sets • Large rivers Livingstone, 63 Meybeck, 1979, 1982 GEMS-Water, 1978 Milliman/Meade/Syvitski, 80’s, 90’s... Meybeck, ragu (GEMS-GLORI) 1995 • small pristine rivers LTER 70’s Meybeck, 80’s • Global data sets on geosphere • runoff vegetation • relief soil • Lithology • GIS tool 90’s • Global human pressures 90’s • population • Urbanisation • Land use • Fertilizers • (Industries) • (minings) • Global scenarios 00’s • Climate chnage • economic • Demographic • Land se • water use • Water policy

  5. 99,5 99 90 75 50 25 10 1 0,5 10 100 0,5 1 10 50 100 PRISTINE RIVER CHEMISTRY PRISRI : GLOBAL DISTRIBUTION OF DIC MEDIUM-SIZED BASINS3 500 - 200 000 km2, rheic basins (n = 480) • DIC CONCENTRATION % • DIC EXPORT % HCO3- / - RARE UNCOMMON COMMON VERY COMMON COMMON UNCOMMON 50 1 10 0,1 RARE g C.m-2.y-1 DIC mg/L In 50% of basins HCO3- exceed 80% of anions DIC concentration ranges over 2 orders of magnitude DIC export ranges over 3 orders of magnitude

  6. GLOBAL BUDGETS ARE REACHING THEIR LIMITS EXAMPLE : DISSOLVED SILICA

  7. Global figures Classification of 15 relief patterns at global scale combining a relief roughness indicator and mean altitude at 30’ resolution, re-aggregated into 7 relief super-classes Relief Typology (Meybeck et al., 2001)

  8. Global river fluxes Mean annual Surface runoff at the 0.5° resolution Database : Fekete et al. 1999, 2001 • The rheic-arheic limit is here set at 3 mm/y on the long term (typically 1 flood every 10 years) • The dry belts may be found in cold (NE Siberia), temperate (Central Asia, Patagonia, Australia) or warm regions (Sahara / Arabia ; Kalahari) • The heterogeneity of the runoff mosaic depends on the resolution

  9. Global figures Organisation of the continental surfaces by water into major units Total area 133 M km2 Exo(%) Endo(%) Σ 25,7 9,0 34,8 Arheic 60,1 5,2 65,2 Rheic Σ 85,8 14,2 100% River network River network : Vörösmarty et al. 2000 a & b, modified and adapted - The arheic areas are below 3 mm/yr annual runoff - Due to uncertainty on the water balance ‘arheic’ areas may occur in non-desertic regions, as NE Siberia, Mackenzie basin, Missouri basin, Patagonia etc. ...

  10. Global figures Relative Water towers of the World as defined for major Köppen climate zones Exorheic Endorheic Water towers = > 2 x mean runoff in the climate zone & mountains H. Dürr 2003 - Polar 332 mm/yr - Cold 251 mm/yr World average runoff in Köppen climate zone: - Temperate 415 mm/yr (exorheic parts) - Dry 18 mm/yr - Tropical 708 mm/yr All climate zones combined: - Endorheic 54 mm/yr

  11. Coastal zone segmentation Average runoff per segment (mm/y) H. Dürr 2003 The upper and lower deciles of coastal basins runoff are >1200 mm/yr and <25 mm/yr (median <200 mm/yr) [endorheic basins not considered]

  12. GLOBAL MAPPING OF RIVER FLUXES COASTAL ZONE SEGMENTATION: TOTAL WATER DISCHARGE PER SEGMENT (km3/y) Most of the continents water is discharged through a limited number of coastal basins : South-East Asia, Congo, Siberia and Amazon-Orenoco

  13. Coastal zone segmentation World distribution of runoff and water fluxes in exorheic basins (115 M km2, n=160, global runoff 358 mm/yr) - 54,6 % of the discharge to ocean (22 800 km3/yr) originates from 18,2 % of exorheic area where annual runoff is between 2 – 5 times the world average - 1,4 % of the discharge (600 km3/yr) originate from 21,8 % of exorheic area where annual runoff is less than 1/5 of the world average H. Dürr 2003

  14. Coastal zone segmentation World distribution of population in exorheic basins (115 M km2, n=160, global average density 45 p/km2) - 26,5 % of the population linked to oceans (1 390 M people) live in 4,2 % of exorheic area where population density exceeds 5 times the world average - 2,8 % of the population (140 M people) live in 35,8 % of exorheic area where population density is less than 1/5 of the world average H. Dürr 2003

  15. GLOBAL SYNDROMES OF RIVERINE CHANGES GLOBAL SYNDROMES OF RIVERINE CHANGES • Flow regulation • River course fragmentation • River bed silting • Neoarheism • Salinization • Chemical contamination asphixiation, inorganic contamination, xenobiotics occurence • Acidification • Eutrophication • (Microbial contamination) • (Aquatic species introduction & invasion)

  16. SOME GLOBAL CHANGES AFFECTING RIVER FLUXES • 2,54 Mkm2 of irrigated land (in dry and semi arid and arid regions) • More than 5 % of global river runoff decrease (> 2000 km3/y) • Hundred of thousands of small to giant reservoirs • Total reservoir area >0,5 M km2 (Great Lakes + Caspian).

  17. NEOARHEISM RIVER FLUXES TRENDS AFTER DAMMING THE COLORADO EXAMPLE (1910-1960) A : annual water flow B : annual sediment flux • Colorado changes are some of the most dramatic change documented in a river system • This evolution was triggered by the construction of the Hoover Dam in 1936 TE17

  18. GLOBAL IMPACT OF LARGE RESERVOIRS : SEDIMENT TRAPPING EFFICIENCY GLOBAL MAPPING • Coastal zone now gets 30% less sediment • 700% increase in water held in rivers • Tripling of river runoff travel times Sediment starving is a growing issue in some coastal zone UNH Vörösmarty et al. 2003

  19. Global nitrogen fluxes through rivers : preindustrial vs contemporary • The global N fluxes (tot N) have increased more than 3 times • Regionally the fluxes have increased more than 10 times • Agriculture and urbanization are the two major N sources Green et al. 2003 UNH

  20. NUTRIENTS FLUXES HETEROGENEITY(From GEMS-GLORI analysis) • AREA CLUSTERS The impacted temperate zone (N. America, Europe, China...) corresponds to 27,5 % of lobal area but to 52 % of P-PO43- fluxes and to 6 % of DIN fluxes to oceans The dry and non- impacted wet tropics plus subarctic regions corresponds to 50,7% of global area and only to 30% of P-PO43- and 21,3 % of DIN fluxes • FLUXES RANKING The most polluted rivers that represent only 5 % of global water discharge would contribute to 32 % of NO3- 48 % of NH4+ 54 % of PO43- fluxes

  21. Regional Analysis : Europe - Continents can be disaggregated into coastal segments and their basins for which the space distribution of Human Pressures is established

  22. Regional Analysis : Europe - Coastal basins are very explicit for global fluxes comparisons (database : Green et al. 2004 Biogeochemistry)

  23. Regional Analysis : Europe Relative weights of European Regional Seas basins (Meybeck and Dürr in preparation)

  24. EUTROPHICATION A SUCCESS STORY : NUTRIENTS CONTROL IN THE RHINE R. mg P /L Van Dijk & Marteijn, 1993 • The major effort of sewage collection was between 1960 and 1975 : it resulted in particulate P abatment and NH4+ decrease • P-PO43- control then decrease was only achieved after the 1985 ban of P detergents and the dephosphatation in most treatment plants

  25. NATURAL SOURCES/SINKS IN RIVER COAST PATHWAYS ATMOSPHERIC FALLOUT 16 NATURAL SOIL WEATHERING LEACHING/EROSION GROUNDWATER HYDROLOGIST SOIL SCIENTIST GEOCHEMIST RIVER BED INCISION 2 1 15 b 15 c 15 a 14 13 3 4 5 6 7 8 9 10 11 12 ALLUVIAL PLAINS DELTAIC SEDIMENT SLOPES LAKES RIVER BED COASTAL SEDIMENT MIDDLE/LOWER COURSE COAST UPPER COURSE ESTUARY/DELTA ESTUARINE SCIENTIST COASTAL SCIENTIST HYDROLOGIST/LIMNOLOGIST

  26. 14 MATERIAL TRANSFER WITHIN THE GEOSPHERE/ANTHROPOSPHERE SYSTEM P ECONOMY/POLICY R ATMOS. POLLUTION BUILDINGS IMPORTED PRODUCTS K ORES M O V Q EXPORTED PRODUCTS H N I J W L B1 CITIES & INDUSTRIES ANTHROPOSPHERE FLUXES MINING ATMOSPHERIC FALLOUT B3 URBAN / INDUS. SOILS B2 TAILINGS G2 16 U DUMPS PARTICULATE MATERIAL DEPOSITORIES GROUNDWATER CONTAMINATION Z H IMPACTED LANDSURFACE E PRISTINE LAND SURFACE SURFICIAL FILTERS F1 G1 F2 T B2 1 J3 A 15 b 15 a RIVERINE TRANSFERS 13 C D 3 4 5 6 7 8 9 10 11 12 RESERVOIRS SLOPES WETLANDS DELTAIC SEDIMENT LAKES ALLUVIAL PLAINS AQUIFERS RIVER BED COASTAL SEDIMENT SINKS & EXCHANGES UPPER COURSE ESTUARY/DELTA COAST MIDDLE/LOWER COURSE Surveys of anthroposphere leaks Surveys of economic material fluxes

  27. MAN AND RIVER RELATIONS EVOLUTION OF CONTINENTAL AQUATIC SYSTEMS FROM HOLOCENE TO ANTHROPOCENE Possible scenarios A : stabilized level, major Earth System change, unmanageable for Human development (laissez-faire) B : stabilized level with maximal acceptable risk for Human development and marked Earth System change (suppression of most polluted sites) C : stabilized level : acceptable risk for Human development with minimal Earth System change (precaution principle) P : return to pre-anthropocene level

  28. DEVELOPMENT OF GLOBAL APPROACHES • Simple extrapolation (Clarke, Livingstone, Alekin, Martin- Meybeck) conc  Q or yields  A • Typologies (e.g. biomes) then extrapolation (Meybeck, 79,82,93; Schlesinger & Melack, 1981) • Multiple regressions with basin natural control factros (runoff, litho, relief) (Fourier, Janssen & Painter, ??) • Mutiple regression then application at fine resolution with global GIS (Probst et al, 90’s) • Mutiple regression with natural and human factors + GIS (Seitzinger, Caraco, 90’s) • Mutiple regression + some processing and routing (e.g. linked to residence time) (Vörösmarty et al., 90’s) Next generation of river inputs • processes  sources and sinks  GCM scenarios  regional • economy & policy scenarios (e.g. Seine, Rhine...).

  29. RECENT PUBLICATIONS • IGPB BAHC Synthesis, Kabat P. et al (2004). Vegetation, Water, Humans and the climate, Springer. • Gobal Sediment fluxes (BAHC-LOICZ-IGPB): Global Planet. Change (2003), 39, 1-2, 1-200. • Global Change and Water (WCRP, IGPB IHDP): Aquatic sciences, 64, 4, 300-400, (2002) • Global change and water vulnerabillity. Phil. Trans. Royal. Soc. B., 58, 1917-2065

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