Climate change impacts on basin-scale water resources

QUEST-GSI (global-scale impacts of climate change) seeks to better quantify the impacts of climate change in a consistent way across the entire globe.

• 2014: QUEST-GSI Basin-scale studies cited in IPCC AR5 WGII Chapter 3 (Figure 3-5).
• 2010: Basin-scale studies from 5 continents published in a special issue of Hydrology and Earth System Sciences
• 2009: Uncertainty in the estimation of PET associated with climate change published in Geophysical Research Letters
• 2009: QUEST-GSI Water Resources Workshop at UCL - programme, presentations & outcomes

• 2009: QUEST-GSI presentations at 2009 General Assembly of the European Geophysical Union

Project rationale and key aims

QUEST-GSI (global-scale impacts of climate change) seeks to better quantify the impacts of climate change in a consistent way across the entire globe, and for a range of sectors including water resources, flooding, crops and human health. The QUEST-GSI research consortium is led by Professor Nigel Arnell of the Walker Institute (University of Reading) and is funded by NERC (UK) under the QUEST: Quantifying and Understanding the Earth System programme.

Climate change impact studies on freshwater resources commonly employ a wide range of socio-economic and climate scenarios. Such variability complicates comparisons of the impacts for different socio-economic and climate futures and prevents a systematic understanding of the effects of proposed policy measures to reduce greenhouse gas emissions. Using a common suite of a climate and socio-economic scenarios and working with partner institutions around the world, UCL-led research assesses the impacts of climate change and future development on freshwater resources at the basin scale and quantifies uncertainty in these predictions.

Basin-scale water resources

Mitigation and adaptation to climate change and accelerated development will normally be conducted at the basin scale. Hydrological models at the basin scale allow for more explicit representations of available freshwater resources (e.g. soil water, groundwater) and demand than is permitted by global macro-scale models, and aid the evaluation of freshwater availability predicted by these macro-scale hydrological models. Basin-scale studies also provide an excellent forum to assess indicator metrics of adaptation, risk and vulnerability defined at the global scale.

High-resolution (0.5º x 0.5º) future climate predictions based on a GCM pattern-scaling approach (ClimGen) will be used to drive basin-scale hydrological models. Pattern scaling which draws from 7 GCMs in the IPCC 2007 AR4 report (CCCMA, CSIRO, IPSL, ECHAM5, NCAR-CCSM3, HadCM3, HadGEM), allows us to evaluate uncertainty among GCMs, SRES scenarios and the magnitudes of mean global air temperature change (at increments of 0.5ºC to 6.0ºC). The latter point is of fundamental importance to policy as it enables a determination of the impact of a given increase in global mean temperature including the so-called 2ºC threshold for 'dangerous climate change'.

Climate and development scenarios will be applied to basin-scale models that cover a broad range of spatial scales and climatic, environmental and developmental conditions (Table 1). Parameter uncertainty in basin-scale hydrological models will be evaluated through the use of ensembles.

Basin	Collaborator	Institution
River Nile tributary (River Mitano)	Daniel Kingston	UCL
River Mekong	Daniel Kingston / Geoff Kite	UCL / Hydro-Logic Solutions
River Okavango	Denis Hughes	Rhodes University, South Africa
River Yangtze tributary (River Xiangxi)	Hongmei Xu	National Climate Centre, China
River Yellow tributary (River Huangfuchuan)	Hongmei Xu	National Climate Centre, China
River Parana tributary (Rio Grande)	Walter Collischonn / Marcio Nobrega	Universidade Federal do Rio Grande do Sul, Brazil
River Mackenzie tributary (River Liard)	Robin Thorne / Ming-ko Woo	McMaster University, Canada

Table 1. QUEST-GSI basin-scale studies and collaborators

QUEST-GSI Water Resources Workshop

The QUEST-GSI Water Resources Workshop, organised by UCL Geography and funded by the NERC QUEST Programme, provided an opportunity for collaborating scientists from China, South Africa, Brazil and Canada to present and discuss latest research findings on the impacts of scaled increases in global mean air temperature (1.0ºC to 6.0ºC in 1.0ºC increments) as well as defined climate and socio-economic scenarios (IPCC SRES A1b, A2, B1, B2) on freshwater resources at the basin scale in the Americas, Africa and Asia. Basin-scale results were also compared with outputs from global hydrological model run at the Walker Institute, University of Reading (UK).

Critically, the workshop also enabled scientists to engage in roundtable discussions of these latest research outputs and their policy implications with stakeholders from WaterAid, World Wildlife Fund, UNESCO-IHP (FRIEND, HELP, GRAPHIC programmes), Global Water System Project, and UK government departments (DECC, DFID, DEFRA). Links to key presentations and messages emanating from the workshop are provided below.

Workshop Key Messages (13 April 2009)

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Presentations

QUEST-GSI Basin-scale water resources

• Richard Taylor, Martin Todd & Julian Thompson, UCL Geography, UK

Projected hydrological change in the Americas

• River Liard Basin, Robin Thorne, Department of Geography, McMaster University, Canada
• Rio Grande Basin, Walter Collischonn & Marcio Nobrega, Universidade Federal do Rio Grande do Sul, Brazil

Projected hydrological change in Africa

• River Okavango Basin, Denis Hughes, IWR, Rhodes University, South Africa
• Tributary of the Upper Nile Basin, Daniel Kingston, UCL Geography, UK

Projected hydrological change in Asia

• River Changjiang (Yangtze) Basin, Yan Huang & Yang Wenfa, Changjiang Water Resources Commission, China
• River Mekong Basin, Daniel Kingston, UCL Geography, UK
• Tributaries of the Yellow and Yangtze Rivers, Hongmei Xu, National Climate Centre, China

Projected global hydrological change

• Global Water Resources, Nigel Arnell, Simon Gosling & Matt Charlton, Walker Institute, University of Reading, UK
• Global - Basin Model Comparison, Simon Gosling & Nigel Arnell, Walker Institute, University of Reading, UK

For further information, please contact Professor Richard Taylor, UCL Geography.