Transcript RIVER INPUTS TO OCEANS AND GLOBAL CHANGE Michel …

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 ?
 When fluxes reacted or will react to global change ?
 Who is responsible for riverine changes ?
 Future evolution evolutions and new track
ASLO-HAWAI 2004
WHY SET UP RIVER FLUXES AT
GLOBAL SCALES ?
QUESTIONS
 Global river we thering rates
PRECURSORS
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
HOW TO CONSTRUCT GLOBAL RIVER FLUXES ?
River Set
Global present figures
Global reconstructs
 small & representative
 flux
 past
 big (concentrations &
yields)
 mapping
 future
 controls
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
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
PRISTINE RIVER CHEMISTRY
PRISRI : GLOBAL DISTRIBUTION OF DIC
MEDIUM-SIZED BASINS
3 500 - 200 000 km2, rheic basins (n = 480)
%
DIC CONCENTRATION
% HCO3- / -
DIC EXPORT
RARE
99,5
99
UNCOMMON
90
COMMON
75
VERY COMMON
50
25
COMMON
10
UNCOMMON
1
0,5
0,1
RARE
1
10
DIC mg/L
10
50
100
In 50% of basins
HCO3- exceed 80% of
anions
0,5
1
10
DIC concentration ranges
over 2 orders of
magnitude
50
g C.m-2.y-1
100
DIC export ranges over
3 orders of magnitude
GLOBAL BUDGETS ARE REACHING THEIR LIMITS
EXAMPLE : 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 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)
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
Global figures
Organisation of the continental surfaces by water
into major units
Total area 133 M km2
Exo(%)
25,7
Endo(%) Σ
9,0
34,8
Arheic
60,1
5,2
65,2
85,8
14,2
100%
Rheic
Σ
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. ...
Global figures
Relative Water towers of the World
as defined for major Köppen climate zones
Exorheic
Endorheic
Water towers =
>2x
mean runoff in
the climate zone
& mountains
World average runoff in Köppen climate zone:
(exorheic parts)
All climate zones combined:
-
Polar
Cold
Temperate
Dry
Tropical
Endorheic
H. Dürr 2003
332 mm/yr
251 mm/yr
415 mm/yr
18 mm/yr
708 mm/yr
54 mm/yr
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]
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
Coastal zone segmentation
World distribution of runoff and water fluxes
in exorheic basins
(115 M km2, n=160, global runoff 358 mm/yr)
Discharge (% of global)
per classes of
river runoff
Area in each class (% of global)
per classes of
river runoff
7,1
6,0
0.01
3.6
18,4
8,7
0.1
36
0.2
72
41,2
0.5
180
18,2
2
716
0,34
5
1790
10 q / q
q(mm/yr)
0,01
0.01
3.6
0,31
0.1
36
1,1
36,2
6,1
0.2
72
0.5
180
2
716
54,6
1,8
5
1790
10 q / q
q(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
Coastal zone segmentation
World distribution of population in exorheic basins
(115 M km2, n=160, global average density 45 p/km2)
Population (% of global
per classes of
population density
Ar e a in e ach clas s (% of global)
pe r clas s e s of
population de ns ity
6,7
17,6
0.01
0.5
0.1
4.5
11,5
0.2
9
17,3
0.5
22
2
90
31,0
5
225
10
450
11,7
4,2
d/d
d(p/km 2)
0,02
0.01
0.5
1,7
1,0
0.1
4.5
5,8
0.2
9
36,8
28,3
0.5
22
2
90
26,5
5
225
10 d / d
450 d(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
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)
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).
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
GLOBAL MAPPING
GLOBAL IMPACT OF LARGE RESERVOIRS :
SEDIMENT TRAPPING EFFICIENCY
• 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
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
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 NO348 % of NH4+
54 % of PO43- fluxes
Regional Analysis : Europe
- Continents can be disaggregated into coastal segments and their basins for which the space
distribution of Human Pressures is established
Regional Analysis : Europe
- Coastal basins are very explicit for global fluxes comparisons
(database : Green et al. 2004 Biogeochemistry)
Regional Analysis : Europe
Relative weights of European Regional Seas basins
(Meybeck and Dürr in preparation)
North Atlantic /
North Sea
Baltic
Arctic
N. Black Sea
N. Mediterranean
Europe
Total
Area
%
23.4
19.7
19.9
25.5
11.5
100
Water
Volume
%
30.7
16.5
23.7
13.9
15.2
100
Population
%
40.7
12.7
1.7
26.4
18.3
100
Suspended
Sediment
%
25.5
3.1
12.0
16.2
43.1
100
Total
Nitrogen
%
48.0
11.2
8.3
15.8
16.7
100
EUTROPHICATION
A SUCCESS STORY : NUTRIENTS CONTROL IN THE
RHINE R.
mg P /L
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
NATURAL SOURCES/SINKS IN RIVER COAST PATHWAYS
ATMOSPHERIC
FALLOUT
16
HYDROLOGIST
SOIL
SCIENTIST
GEOCHEMIST
NATURAL SOIL
WEATHERING
LEACHING/EROSION
GROUNDWATER
RIVER BED
INCISION
2
1
15 b
15 a
15 c
14
3
4
SLOPES
UPPER COURSE
5
13
6
LAKES
7
ALLUVIAL
PLAINS
8
9
RIVER
BED
10
11
DELTAIC
SEDIMENT
MIDDLE/LOWER COURSE
12
COASTAL
SEDIMENT
COAST
ESTUARY/DELTA
HYDROLOGIST/LIMNOLOGIST
ESTUARINE
SCIENTIST
COASTAL
SCIENTIST
MATERIAL TRANSFER WITHIN THE GEOSPHERE/ANTHROPOSPHERE SYSTEM
P
ECONOMY/POLICY
R
ATMOS. POLLUTION
ORES
M
O
K
V
Q
H
J
W
B1
EXPORTED
PRODUCTS
N
I
L
ANTHROPOSPHERE
FLUXES
CITIES & INDUSTRIES
MINING
ATMOSPHERIC
FALLOUT
16
IMPORTED
PRODUCTS
BUILDINGS
B3
URBAN / INDUS. SOILS
B2
U
G2
TAILINGS
Z GROUNDWATER
IMPACTED
PRISTINE
LAND SURFACE
H
E
CONTAMINATION
SURFICIAL
FILTERS
LANDSURFACE
1
F1
G1
F2
T
B2
J3
A
DUMPS PARTICULATE
MATERIAL DEPOSITORIES
14
15 b
15 a
13
3
4
5
C
D
6
7
8
9
10
11
RIVERINE
TRANSFERS
12
RESERVOIRS
SLOPES
WETLANDS
LAKES
UPPER COURSE
ALLUVIAL
PLAINS
AQUIFERS
Surveys of economic material fluxes
DELTAIC
SEDIMENT
ESTUARY/DELTA
MIDDLE/LOWER COURSE
Surveys of anthroposphere leaks
RIVER
BED
COASTAL
SEDIMENT
COAST
SINKS &
EXCHANGES
MAN AND RIVER RELATIONS
EVOLUTION OF CONTINENTAL AQUATIC
SYSTEMS FROM HOLOCENE TO ANTHROPOCENE
STATE INDICATOR
MODELS SCENAR IOSŹ/Ź
PROJEC TIONS
DIRECT SU RVEY S
ARCH EOLOGI CALŹ/ŹHISTORICALŹDATA
EN VIRONMENTAL ARCH IVES
100Ź000
10Ź000
1Ź000
1Ź800
1Ź950
2Ź000
2Ź050
TIME
RESPONSES OF CONTINEN TAL AQUATIC SYSTEMS TO CLIMATE
VARIABILITY, LAN D COVER CHA NGE & DIREC T HUMAN PRE SSURES
STATE INDICATOR
RESPONSES OF C.A.S. TO WATER US ES & LAND USE
A
QM
HM
B
C
P
Hm
Qm
100Ź000
10Ź000
1Ź000
BP
BP
AD
1Ź800
1Ź950
2Ź000
2Ź050
HOLOCENE
ANTHROPOCENE
TIME
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
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...).
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