WHY SET UP RIVER FLUXES AT GLOBAL SCALES ?

QUESTIONS PRECURSORS

Global river weathering 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

ATMOSPHERE

ANTHROPOSPHERE

TERRESTRIAL VEGETATION, SOIL

GROUNDWATERS

RESERVOIRS LAKES

CONTINENTAL SEDIMENTS

SURFICIAL LITHOSPHERE

COASTALZONE

OPEN

OCEAN

WETLANDS

RIVERS

COASTALSEDIMENT

OCEANSEDI-MENT

8 9

10

13 14

21

16 SILTING15

UPLIFT

11

CH4 CO2 WATER

17

WATER CH4 CO2

5

EROSION

WEATHERING

43, 5

CH4 CO2 NO2

CH4 N2OWATER DUST

CH4 CO2 N2O6

12

CO2

ENERGY

WATER

SEDIME NTS

CARBON

NUTRIENT S

additional fluxes or reservoirs due to human activities

2 0

18

7 19

7, 1222 22

CONTINENTAL AQUATIC SYSTEMS AT THE ANTHROPOCENE

Relief Typology (Meybeck et al., 2001)

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

Combining lithology and relief typology

OCCURRENCE OF CONTINENTAL AREA EXPOSED TO WATER WEATHERING (RHEIC REALM) AND TO RIVER

FLUXES TO THE OCEANS (EXORHEIC REALM)

• 10.7% of the present land is glaciated

• 33.7% is arheic (less than 3 mm/y runoff)

• 90% of weathering fluxes is related to 30% of the continents area

A% land

area

B% weath.

flux

C% flux to

oceanGlaciated16 Mkm2 10.7 0.1 ? 0.1 ?

Total land149 Mkm2 EndorheicArheic

50,2 Mkm2

Exorheic33.7 0 0

Nonglaciated133 Mkm2

Endorheic 3.4 1 0Oligorheic

Exorheic 21 7 7Rheic82,8 Mkm2

Endorheic 1.1 2 0Mesorheic

Exorheic 27.3 53 55

Hyperheic Exorheic 2.75 37 38

GLOBAL MAPPING OF RIVER FLUXESGLOBAL MAPPING OF RIVER FLUXES

Organisation of the continental surfaces by water into major units

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

Global figures

- 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. ...

Total area 133 M km2

PLAINSHILLS

PLATEAUXMOUNTAINS

PLATEAUXHILLS PLAINS

EXORHEIC ENDORHEIC

37 200 km3 y-1 940 km3 y-1

Area [M km2]

62.7 11.1 14.3 27.6 5.75 2.5 0.4 8.7

Runoff [mm y-1]

293 445 153 424 86 37.5 102 35

Population density [p km2]

46.5 67 26.5 46 35 11 36 16

Global average river runoff and population density for major relief classes

(after Meybeck et al. 2000).

FLUVIAL NETWORK (POTENTIAL) AT THE LATE GLACIAL FLUVIAL NETWORK (POTENTIAL) AT THE LATE GLACIAL MAXIMUM (18 000 BP)MAXIMUM (18 000 BP)

• Most of North America and of Europe was glaciated

• Due to lower sea level (-120m) an extended area of continental platform was exposed to river transport (e.g. West Siberia and Bering sea, South China

and Aragura seas, Patagonia)

HOLOCENE/ANTHROPOCENE EVOLUTIONHOLOCENE/ANTHROPOCENE EVOLUTION

H. Dürr,Sisyphe

BASALT OUTCROPS FOR SIX CLASSES OF RIVER RUNOFFBASALT OUTCROPS FOR SIX CLASSES OF RIVER RUNOFF

• Basalts of various ages are found at various positions on all continents

• They are exposed to temperature ranging from -10°C to +30°C

• Hower the main weathering control is probably the river runoff ranging over 2 orders of magnitude, even at the regional scale (e.g. african rift

valley and Deccan)

CHEMICAL FLUXES CONTROLSCHEMICAL FLUXES CONTROLS

Runoff : UNH Litho : H. Dürr, Sisyphe

VARIABILITY OF NATURAL RIVER VARIABILITY OF NATURAL RIVER CHEMISTRY AND LITHOLOGYCHEMISTRY AND LITHOLOGY

Sum of cations (µeq/L) Dominant ions Example

50 Ca2+, Cl- Rio Negro * (Amazonia) quartz sands

70 Na+, HCO3- Rio Tefe * (Amazonia) quartz sands

500 Mg2+, Ca2+, HCO3- Basaltic basins

600 Mg2+, HCO3- Peridotite basins

4 000 Ca2+, HCO3- Carbonated basins

5 000 Mg2+, SO42- Coal schists

9 000 Na+, SO42- Semliki R. Rift Valley

20 000 Na+, SO42- Bituminous Shale (Montana)

50 000 Na+, Cl- Urubamba tributary (Amazonia)

* Rain and vegetation control

There is no mean river water that can be used as a global or even regional reference

PRISTINE RIVER CHEMISTRYPRISTINE RIVER CHEMISTRY

GLOBAL OCCURENCE (% of area) OF WATER TYPES GLOBAL OCCURENCE (% of area) OF WATER TYPES AND THEIR ORIGINS (Pristine rivers model)AND THEIR ORIGINS (Pristine rivers model)

• Ionic types in pristine rivers are more diverse than originally thought by Gibbs (1972)

• CaCo3 is dominating in 77% of rivers (area weighted)• Rain and vegetation recycling is dominating over 2.6% of the

continents area and the evaporation over 8.2% (rheic realm only, runoff > 3 mm)

• Rock weathering control extends over 89% of the continents area

• Evaporated waters may result in many chemical types

Origin Rock dominated

Type% Total

Raindominated Silicate Carbonate Pyrite Evaporites

Evaporated

Na2SO4 3,2

NaCl 6,8

Na2CO3 3,6

MgCO3 2,4

MgSO4 2,0

MgCl2 0,1

CaSO4 5,2

CaCO3 76,9

Total 100 2,6 35,4 45,1 5,2 3,6 8,2

PRISTINE RIVER CHEMISTRYPRISTINE RIVER CHEMISTRY

PRISRI : GLOBAL DISTRIBUTION OF DIC PRISRI : GLOBAL DISTRIBUTION OF DIC MEDIUM-SIZED BASINSMEDIUM-SIZED BASINS

3 500 - 200 000 km3 500 - 200 000 km22, rheic basins (n = 480) , rheic basins (n = 480)

% HCO3- / - DIC CONCENTRATION DIC EXPORT

99,599

90

75

50

25

10

10,5

RARE

UNCOMMON

COMMON

VERY COMMON

COMMON

UNCOMMON

RARE

10 50 1000,5 1 10 100

DIC mg/L

0,1 1 10 50

g C.m-2.y-1

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

%

PRISTINE RIVER CHEMISTRYPRISTINE RIVER CHEMISTRY

Natural Space Variability of River Suspended Fluxes

A. TSS Weighted means mg/L 

Very low Low Medium High Very highExtremely

high

5 - 20 20 - 100 100 - 500500 - 2 00

02 000 - 10 

000> 10 000

Annapolis (NS)

St. Lawrence

Sacramento (CA)

Red Deer (Alb)

Stikine (BC)

Eel (CA)

Matanuska 

(AL)

Mississippi

Rio Grande (TX

)

Colorado (AZ)

Little Colorado 

(AZ)

Control factors : relief, lakes, lithology, runoff.Ref : Meybeck, Laroche, Dürr, Syvitski, 2003. Glob.Planet.Change

Natural Space Variability of River Suspended Fluxes

B. Daily TSS Yields kg.km-2.d-1

Very low Low Medium High Very highExtremely

high

< 10 10 - 50 50 - 200200 - 1 00

01 000 - 5 0

00> 5 000

Lacustrine Rhone (CH)

St. Lawrence

Chaudière (PQ)

Sacramento (CA)

Mississippi

Colorado (AZ)

Eel (CA)

Alpine Rhine (CH)

Control factors : relief, lakes, runoff, river regime, lithology. Ref : Meybeck, Laroche, Dürr, Syvitski, 2003. Glob.Planet.Change

Natural Space Variability of River Suspended Fluxes

C. % of time needed to carry 50% of TSS flux

Very long Long Medium Short Very shortExtremely

short

> 16% 16 - 8% 8 - 3,4% 3,4 - 1,4% 1,4 - 0,4% < 0,4%

Mississippi

St. Lawrence

Fraser (BC)Sacrament

o (CA)

Red Deer (Alb)

Stikine (BC)

Eel (CA)Walla-

Walla (OR)

Control factors : basin size, river regime.  Ref : Meybeck, Laroche, Dürr, Syvitski, 2003. Glob.Planet.Change

GLOBAL BUDGETS ARE REACHING THEIR LIMITS GLOBAL BUDGETS ARE REACHING THEIR LIMITS EXAMPLE : DISSOLVED SILICAEXAMPLE : DISSOLVED SILICA

Global average (mg/L) Approach

Clarke, 1924 8,3 Few, big temperate rivers

Livingstone, 1963 13,1 d.o.

Meybeck, 1979 10,4 Biomes typology, 60 rivers, Amazon included

Probst, 1992 8,9 Multiregression (Meybeck’s data)

Meybeck and Ragu, 1996 7,7 250 rivers no typology

Meybeck, 1999 (unpubl.) 9,2 d.o. + 9 morphotectonic tpes (lytho. Control)

Treguet et al., 1995 9,0 (Meybeck + Ragu data)

Meybeck (unpubl.) 8,75 43 pristine rivers and tribs (exorheic + endorheic)

GLOBAL SEDIMENT YIELD MAPGLOBAL SEDIMENT YIELD MAP

Sediment yields reflect land erosion : they are maximum in South East Asia where heavy rainfall, active tectonics and erodible rocks are found

Ludwig et al, 1998

GLOBAL MAPPING OF RIVER FLUXESGLOBAL MAPPING OF RIVER FLUXES

GLOBAL DISTRIBUTION OF RIVERS RANKED PER INCREASING TOTAL DISSOLVED SOLIDS (∑+ cation sum)

(pristine rivers model, n = 1 329 basins)

• The most commonly found ionic content (∑+) at the continents surface is between 375 and

6000 µeq/L

• The most commonly found ionic content (∑+) in one liter of water is

between 375 and 1500 µeq/L

• The ionic fluxes are essentially related to medium-mineralized

waters, between 750 and 6000 µeq/L

% AREA

%  WATERFLUXES

% IONICFLUXES

0

5

10

15

20

25

30

1 2 3 4 5 6 7 8 9

0

5

10

15

20

25

30

1 2 3 4 5 6 7 8 9

0

5

10

15

20

25

30

1 2 3 4 5 6 7 8 9

+(µeq/L)

PRISTINE RIVER CHEMISTRYPRISTINE RIVER CHEMISTRY

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)

GLOBAL SYNDROMES OF RIVERINE GLOBAL SYNDROMES OF RIVERINE CHANGESCHANGES

SOME GLOBAL CHANGES AFFECTING RIVER FLUXESSOME 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).

RIVER FLUXES TRENDS AFTER DAMMING RIVER FLUXES TRENDS AFTER DAMMING THE COLORADO EXAMPLE (1910-1960)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

NEOARHEISMNEOARHEISM

• Coastal zone now gets 30% less sediment• 700% increase in water held in rivers• Tripling of river runoff travel times

UNH

Vörösmarty et al. 2003

Sediment starving is a growing issue in some coastal zone

GLOBAL MAPPINGGLOBAL MAPPING

GLOBAL IMPACT OF LARGE RESERVOIRS : SEDIMENT TRAPPING EFFICIENCY

Global nitrogen fluxes through rivers : preindustrial vs contemporary

UNHGreen et al. 2003

• 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

NUTRIENTS FLUXES HETEROGENEITYNUTRIENTS FLUXES HETEROGENEITY(From GEMS-GLORI analysis)(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-PO4

3- 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-PO4

3- 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 PO4

3- fluxes

Conclusions- Coastal basins morphology is highly variable from narrow strips

(Peru-Chile) to very deep basins (Mississippi-Amazon) - Mean runoff in coastal basins range over 3 orders of magnitude as

for other river fluxes (sediments, carbon, nutrients) - Population pressure within coastal basins varies over more than 2 orders of magnitude from 0.3 inhab/km2 for the Laptev Sea or the Gulf of Carpentaria to more than 300 inhab/km2 in

South and East Asia

- Direct inputs to open oceans are actually limited by extended mediterranean type seas (Mediterranean proper, Black Sea, Gulf of Mexico / Caribbean, …) and by other regional seas (Persian Gulf, Adaman)

- Our segmentation allows for determination of first order inputs to Oceans (e.g. North Atlantic) as well as second order inputs for about 30 regional seas