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Climate change impacts on basin-scale water resources


Impact of climate change on freshwater resources: an inter-basin comparison using a consistent set of scenarios; Uncertainty in the estimation of PET associated with climate change

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.

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

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


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

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