Download Global Drivers of Change

UK – China Workshop, July 2008
Global Change and Water
Dr Richard Harding
Centre for Ecology & Hydrology
Wallingford UK [email protected]
Coordinator of the FP 6 WATCH – Water
and Global Change Integrated Project
Global Drivers of Change
•
Increasing population
•
Increasing water consumption
•
Land cover/use change
•
Increasing greenhouse gases
Global Drivers of Change:
interactions
rainfall
GHGs
Land cover
Climate
Water
Resources
food
fuel
GHGs
Population,
Increasing
consumption
Water Consumption
- after Shiklomanov 2000
3000
Assessment
Consumption, km 3/year
2500
2000
Agriculture
Forecast
Industry
1500
Municipal
needs
Reservoir
1000
Total
500
0
1900
1920
1940
1960
1980
2000
2020
2040
Regional Water Scarcity
• One Indicator is the ratio of Water Consumption to Water
Availability
– World: 1995: 8,4 %
2025: 12,2 %
• But:
– South America:
2025: 1 – 2 %
– Asia:
1995: 40 – 80 %
2025: 60 – 85%
– North Africa: 1995: 95 %
2025: 130 %
– In some countries already more than 100% of the yearly
water supply is consumed. This is unsustainable!
Impacts of Climate Change
Regional Rainfall Changes
FIGURE SPM-6. Relative changes in precipitation (in percent) for the period 2090–2099,
relative to1980–1999. Values are multi-model averages based on the SRES A1B scenario
for December to February (left) and June to August (right). White areas are where less
than 66% of the models agree in the sign of the change and stippled areas are where
more than 90% of the models agree in the sign of the change.
Areas of physical and economic
water scarcity (IWMI, 2006)
Precipitation/Runoff
transform curves
Precipitation
Discharge
‚hard rock‘ catchment
Groundwater
catchment
Time
Hydrological modelling systems
Grid-to-Grid
Evaporation,
E
Precipitation, P
Topographic
gradient, g
Surface flowrouting
Smax
River
Saturation-excess
surface runoff
S
River
flow
Return
flow
Drainage,
D = KdS3
Subsurface
flow-routing
Runoff production at each grid-cell. Kinematic wave routing from grid
to grid.
UK application of prototype model: using the
UK Hadley Centre 25km RCM output
Precipitation,
Percentage
change in
flood peaks at
a 20-year
return period
(from 1970s
to 2080s)
Evaporation,
E
P
Topographic
gradient, g
Surface flow routing
S max
River
Saturation -excess
surface runoff
S
River
flow
Return
flow
Drainage,
3
D = KdS
Subsurface
flow -routing
Grid to Grid
Climate Impacts Uncertainty in
flood estimation
River Beult in
South East
England (Kent)
Natural variability:
Emissions:
Global Climate Model structure:
GCM initial conditions:
Downscaling:
RCM structure:
Hydro’ model structure:
Hydro’ model parameters:
-34
-14
-13
-25
-22
-5
-45
+1
to
to
to
to
to
to
to
to
+17
-9
+41
-5
-8
+8
- 22
+7
Recurrence interval (years)
Kay, A.L., Davies, H.N., Bell, V.A. & Jones, R.A. Comparison of uncertainty sources for climate change impacts: flood frequency in the UK. Submitted: Climatic Change.
1989
2000
SAGARMATHA: Snow and Glacier Aspects of
Water Resources Management in the Himalaya
60
Basin boundary
Country boundary
DCW Glaciers
RCM T Change
0 - 1 deg C
1 - 2 deg C
2 - 3 deg C
3 - 4 deg C
4 - 5 deg C
5 - 6 deg C
No Data
40
20
%change in decadal mean
flow for Ganges from
regional climate model
output (RCM2)
Temperature
change
0
1
0
200
Uttarkashi
2
3
4
40
5
6
Allahbad
-20
400
600
800
1000 Kilometers
Basin boundary
Country boundary
DCW Glaciers
RCM P Change (%)
-100 - -50
-50 - 0
0 - 50
50 - 100
100 - 150
150 - 200
200 - 400
400+
No Data
-60
0
Uttarkashi
0
1
2
3
4
400
600
800
6
7
Haridwar
Allahbad
-40
-60
-80
-80
Precipitation change
5
Kanpur
-20
Decade
200
Haridwar
Kanpur
-40
0
7
20
% change
% change
60
0
Decade
1000 Kilometers
http://www.nwl.ac.uk/ih/www/research/SAGARMATHA/
The WATCH Integrated Project
analyse and describe the current
global water cycle
evaluate how the global water
cycle and its extremes respond to
future drivers of global change
evaluate feedbacks in the
coupled system as they affect the
global water cycle
Feedbacks in
the climate
hydrological
system
Past, present
and future
population,
LUCC and
water demand
Extremes and
scales of
hydrological
events
WB5
WB2
WB4
20th Century Global water cycle
WB1
21st Century Global water cycle
WB3
Assessing the vulnerability of water resources
evaluate the uncertainties in the
predictions
develop a modelling and data
framework to assess the future
vulnerability of water as a
resource
WB6
Management, training and
dissemination
WB7
WATCH
New data products:
1. forcing data
Time v time-scale coverage for reanalysis products and observations
100 years
10 years
1 year
1 month
1 hour
1 day
2010
ERA Interim
2000
1990
Micro-met
observs.
GSWP2
1980
Year
1970
ERA40
1960
NCEP-NCAR
1950
1940
1930
1920
1910
CRU 2.1
1900
0.01
0.1
1
10
100
1000
10000
Time-steps per year
New data products:
2. global fields -soil
30” degree resolution
Combines data from ESB, USDA, SOTER, FAO, CHINA for
the best soil dataset available.
New data products:
3. global fields – population past and future
0.5 degree resolution
10 year time steps
IPCC SRES A2r, B1, B2 scenarios
International Institute for Applied System Analysis (IIASA) GGI Scenario Database,
2007. Available at: http://www.iiasa.ac.at/Research/GGI/DB/
Characteristics of models
Global Hydrological Models:
GHM
High resolution
Good representation of processes and anthropogenic interventions
(dams, landuse, abstractions etc)
Good links to water requirements
Quick to run/modify
Land Surface Hydrology Models
LSHM
RBHM
Realistic representation of energy and evaporation
Limited calibration
Include many feedbacks (CO2, snow etc)
Poor on anthropogenic river modification
Complex to run and modify (need diurnal forcing etc)
River Basin Hydrological Models
Realistic – particularly flow processes, quality etc
Good on floods etc
Often rely on calibration to particular basins
WaterGAP 2 Model
- Overview •Land Cover
•Climate
Global
Hydrololgy
Water Availability
• Runoff
• Groundwater recharge
calibration
River discharge
•Population
•Income
•Technology
•Climate
Global Water
Use
River Basin
Water Stress
Water
Withdrawals
Wastewater
Loadings
Model Intercomparison
Land
surface
hydrology
models
Global hydrology
models
River basin models
G2G
WATCH
– some deliverables
•
Improving hydrological components of global hydrology
models: groundwater, routing (incl. dams etc), irrigation,
inundation, ice ....
•
New validation – runoff, evaporation ..
•
Improved driving fields – global 0.5o fields for 20th and 21st
century
•
Regional reanalyses
•
Improved land cover/land use fields
•
Model intercomparison with GHMs and LSHMs
•
Uncertainty analyses of current and future runoff
WATCH / MAIRS / UKRC
China Science Workshop:
24-28 November 2008 (tentative)
Beijing, China
Climate Change & Global Water Cycle
The workshop will explore:
•our current state of knowledge of components
of the water cycle, globally and regionally.
•recent advances in large scale climate and
hydrological modeling in China and Europe.
•research interests in China and Europe.
•possibilities for joint research
Thank you