Simon Gosling and Nigel Arnell

QUEST-GSIImpacts of climate change on global

water resourcescomparison with catchment results

QUEST-GSI water resources workshopUCL March 2009

MacPDM performance

Tends to overestimate runoff in dry regions –evaporation of runoff and transmission loss

Mac-PDM validation (with GRDC data)

Tends to overestimate runoff in dry regions –evaporation of runoff and transmission loss:

Mac-PDM validation (with GRDC data)

Black=observed

Grey=simulated

No routing

Change in runoff: priority A1b emissions

Change in runoff: with increasing temp

Changes in magnitude and extent

2050s runoff change from present – A1B models

2050s runoff change from present – A1B models

2050s runoff change from present – A1B models

2050s runoff change from present – A1B models

2050s runoff change from present – A1B models

Agreement with catchment model for larger changes in magnitude but not for smaller changes

Implications for policy decision-making

2050s A1B Models

2050s A1B Models

PE Calculation Methods• Penman-Monteith vs. Priestley Taylor

– Baseline (CRU-TS3 1961-1990)

2050s A1B Models

‘Envelope’range varies by catchment

Tendency for similar sign of change

1-month lag from catchment model (routing)

Prescribed HadCM3

Agreement with catchment model – PE dominates at higher temperatures

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