Transcript Slide 1
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 GHGs food fuel Population, Increasing consumption
Water Consumption
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after Shiklomanov 2000
3000 Assessment 2500 2000 Forecast 1500 1000 500 0 1900 1920 1940 1960 1980 2000 2020 2040 Agriculture Industry Municipal needs Reservoir Total
Regional Water Scarcity
• • One Indicator is the ratio of Water Consumption to Water Availability – World: 1995: 8,4 % 2025: 12,2 %
But:
– South America: – Asia: 1995: 40 – 80 % – North Africa: 1995: 95 % 2025: 1 – 2 % 2025: 60 – 85% 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
Discharge Precipitation ‚hard rock‘ catchment Groundwater catchment Time
Hydrological modelling systems
Precipitation,
P
Evaporation,
Grid-to-Grid
E
Topographic gradient,
g
Surface flow routing
S max
River Saturation-excess surface runoff
S
River flow Return flow Drainage,
D = K d S 3
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,
P
Saturation -excess surface runoff River flow Return flow River Grid to Grid Evaporation,
E
Surface flow routing Topographic gradient,
g S max S
Subsurface flow -routing Drainage,
D = K d 3
Percentage change in flood peaks at a 20-year return period (from 1970s to 2080s)
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 +17 to - 9 to +41 to - 5 to - 8 to +8 to - 22 to + 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 40 20 0
Temperature change 0 200 400
-20
600
-40
800 1000 Kilometers
-60 -80
Precipitation change
2
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
3 60 40 20 0 0 -20 4
%change in decadal mean flow for Ganges from regional climate model output (RCM2)
1 2 5 3 4 6 5 6 7 Uttarkashi Haridwar Kanpur Allahbad 7 Uttarkashi Haridwar Kanpur Allahbad
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
-40 -60 -80
Decade Decade 0 200 400 600 800 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 evaluate the
uncertainties
in the predictions develop a modelling and data framework to assess the future
vulnerability of water as a resource
20 th Century Global water cycle 21 st Management, training and dissemination
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 day 1 hour 2010 2000 1990 1980 1970 1960 1950 1940 1930 1920 1910 1900 0.01
0.1
1 CRU 2.1
10 100 ERA Interim Micro-met observs.
GSWP2 ERA40 NCEP-NCAR 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/
GHM LSHM RBHM
Characteristics of models
Global Hydrological Models:
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
Realistic representation of energy and evaporation Limited calibration Include many feedbacks (CO 2 , 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
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Land Cover
•
Climate
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Population
•
Income
•
Technology
•
Climate
WaterGAP 2 Model - Overview -
Global Hydrololgy
calibration
River discharge Water Availability
• Runoff • Groundwater recharge
River Basin Water Stress Global Water Use
Water Withdrawals Wastewater Loadings
Land Surface Hydrology Mode/ Global Hydrology Model Intercomparison
Global hydrology models Land surface hydrology models G2G River basin models
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 0.5
o century fields for 20 th and 21 st • 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