Dr Richard Harding

Centre for Ecology & HydrologyWallingford UK rjh@ceh.ac.uk

Coordinator of the FP 6 WATCH – Water and Global Change Integrated Project

Global Change and Water

Global Drivers of Change:interactions

Land cover

Population,Increasing

consumption

Climate

rainfallGHGs

foodfuel

GHGs

WaterResources

Impacts of Climate Change

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.

Regional Rainfall Changes

‘ The Integrated Project (WATCH) which will bring together the hydrological, water resources and climate communities to analyse, quantify and predict the components of the current and future global water cycles and related water resources states, evaluate their uncertainties and clarify the overall vulnerability of global water resources related to the main societal and economic sectors.’

WATCHWB7

Assessing the vulnerability of water resources

WB6

Past, present and future population, LUCC and

water demandWB2

Extremes and scales of

hydrological events

WB4

Feedbacks in the climate hydrological

system

WB5

21st Century Global water cycle

20th Century Global water cycle

WB3

WB1

Management, training anddissemination

WATCHWB7

Assessing the vulnerability of water resources

WB6

Past, present and future population, LUCC and

water demandWB2

Extremes and scales of

hydrological events

WB4

Feedbacks in the climate hydrological

system

WB5

21st Century Global water cycle

20th Century Global water cycle

WB3

WB1

Management, training anddissemination

WB7WB7

Assessing the vulnerability of water resources

WB6Assessing the vulnerability of water resources

WB6

Past, present and future population, LUCC and

water demandWB2

Past, present and future population, LUCC and

water demandWB2

Extremes and scales of

hydrological events

WB4

Extremes and scales of

hydrological events

WB4

Feedbacks in the climate hydrological

system

WB5

Feedbacks in the climate hydrological

system

WB5

21st Century Global water cycle

20th Century Global water cycle

WB3

WB1

21st Century Global water cycle21st Century Global water cycle

20th Century Global water cycle20th Century Global water cycle

WB3

WB1

Management, training anddissemination

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

The WATCH Integrated Project

New data products (to enable the full range of hydrological models to be run and evaluated):

1. Global forcing data – half degree forcing data, daily and sub-daily for 20th C

2. 21st C bias corrected forcing data

3. Regional forcing data sets 0.1o

4. Land cover for 20th and 21st C

5. Population and water use for 20th and 21st C

population

soils

WATCH Forcing Data

• Based on ERA40 Reanalysis.

• 0.5o x 0.5o (inc. elevationcorrection).

• Tair monthly bias corrected viaCRU-TS2.1-PIK (discontinuitiesremoved).

• SWdown corrected for decadalchanges in aerosol loading.

• Precipitation bias corrected using GPCCv4 and CRU-TS2.1 as analternative.

• Precipitation corrected for averagegauge undercatch (Rainf & Snowfseparately).

• 1958-2001 completed July 20091901-1957 completion in 2010

0.01 0.1 1 10 100 1000 100001900

1910

1920

1930

1940

1950

1960

1970

1980

1990

2000

2010

Yea

r

1 hour1 day1 month1 year10 years100 years

Time-steps per year

Micro-met observs.

ERA40

CRU TS2.1GPPC v4

GHM

Global Hydrological Models:High resolutionGood representation of processes and anthropogenic interventions

(dams, landuse, abstractions etc)Good links to water requirementsQuick to run/modify

LSHMLand Surface Hydrology Models

Realistic representation of energy and evaporationLimited calibrationInclude many feedbacks (CO2, snow etc)Poor on anthropogenic river modificationComplex to run and modify (need diurnal forcing etc)

RBHMRiver Basin Hydrological Models

Realistic – particularly flow processes, quality etcGood on floods etcOften rely on calibration to particular basins

Characteristics of models

Global hydrologymodels

Land surface hydrology models

Vegetation models

WaterMIP: Land Surface Hydrology Model/ Global Hydrology Model Intercomparison

HBVWATBAL

BilanFRIER

River basin Models

Mean annual water fluxes:Comparison to Biemans (2008)

Courtesy of Hester Biemans

River basins

MacKenzieMississippiAmazonParana

RhineDanubeVolga

NigerNileCongoOranje

LenaIndusGanges-B.MekongHuangHeChang Jiang

Murray-Darling

Mean annual water fluxes

T

1 gwava

2 h07

3 jules

4 lpj

5 macpdm

6 matsiro

7 mpi−hm

10 vic

11 watergap

12 wbmplus

0

440

880

1320

1760

0 440 880 1320 1760

Amazon1 gwava

2 h07

3 jules

4 lpj

5 macpdm

6 matsiro

7 mpi−hm

10 vic

11 watergap

12 wbmplus

0

440

880

1320

1760

0 440 880 1320 1760

Lena

1 gwava

2 h07

3 jules

4 lpj

5 macpdm

6 matsiro

7 mpi−hm

10 vic

11 watergap

12 wbmplus

0

440

880

1320

1760

0 440 880 1320 1760

Changjiang

1 gwava

2 h07

3 jules

4 lpj

5 macpdm

6 matsiro

7 mpi−hm

10 vic

11 watergap

12 wbmplus

0

440

880

1320

1760

0 440 880 1320 1760

Ganges−Brahm.

1 gwava

2 h07

3 jules

4 lpj

5 macpdm

6 matsiro

7 mpi−hm

10 vic

11 watergap

12 wbmplus

0

440

880

1320

1760

0 440 880 1320 1760

Oranje

1 gwava

2 h07

3 jules

4 lpj

5 macpdm

6 matsiro

7 mpi−hm

10 vic

11 watergap

12 wbmplus

0

440

880

1320

1760

0 440 880 1320 1760

Danube

Runoff (mm year-1)

Eva

potra

nspi

ratio

n(m

m y

ear-1

)

R Niger – monthly Evaporation

Simulations from 8 models for the Ganges basin (1985-1999)

ResultsGlobal 0.25 degree evaporation product in mm per year

Diego Miralles1, Thomas Holmes1,2, Richard de Jeu1, John Gash1, Han Dolman11VU University Amsterdam, 2USDA Beltsville USA

Supported by WATCH EU 6th framework

Input: •Radiation (NASA/GEWEX Surface Radiation Budget (SRB) V3 )•Surface temperature (based on microwave observations, Holmes et al., 2009)•Continuous vegetation field (modis; forest, herbaceous and bare soil fraction)•SRTM DEM for the estimation of air pressure

Issues

There is still considerable uncertainty in most components of the water cycle globally

Future projections are quite uncertain – particularly regionally

Changes in Extremes – floods and droughts may be more important

Feedbacks between the hydrological state and atmosphere will be important regionally

We need to improve our land surface and large scale hydrological models

We need to find better ways of quantifying and communicating uncertainty

‘ The Integrated Project (WATCH) which will bring together the hydrological, water resources and climate communities to analyse, quantify and predict the components of the current and future global water cycles and related water resources states, evaluate their uncertainties and clarify the overall vulnerability of global water resources related to the main societal and economic sectors.’