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| Titel |
Using probabilistic climate information for UK water resource planning |
| VerfasserIn |
Jean-Philippe Vidal, Birgitte von Christierson, Steven D. Wade |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250050555
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| Zusammenfassung |
| Water companies in the United Kingdom have considered climate change in their water
resources plans for more than a decade. Over this period, UK Water Industry Research
(UKWIR) funded a series of studies that provided changes in UK hydrology and practical
methods for including climate change in water resources plans. Following the dissemination
of the probabilistic UK Climate Projections 2009 (UKCP09, Murphy et al., 2009), UKWIR
launched an initial study of the impacts of these new scenarios on future water resources
(Christierson et al., 2009). This paper presents an initial assessment of the impact of UKCP09
on river flows at a national scale for the 2020s and the implications for water resource
planning.
UKCP09 provide for the first time probabilistic projections, available as statistical
distributions of changes in climate variables under the A1B emissions scenario. The
probabilistic nature of UKCP09 represents an opportunity to move to a risk-based impact and
adaptation decision-making framework, but propagating such probabilistic information into
impact studies is particularly challenging. A practical approach has been developed here by
applying a Latin Hypercube Sampling to monthly distributions of changes over UK
river-basin regions and perturbing historical climate series. A hydrological modelling
framework developed for the previous national-scale assessment (Vidal & Wade, 2007) has
been applied here to 70 catchments across the UK. This framework is based on two model
structures widely used for climate change impact studies: PDM, a lumped conceptual model,
and Catchmod, a semi-distributed conceptual model. It also makes use of the Generalized
Likelihood Uncertainty Estimation (GLUE) methodology to provide information on model
parameter uncertainty.
River flow changes for the 2020s are presented in a probabilistic way, with maps of
quartile values as well as detailed distributions for two catchment case studies: the
Ribble at Arnford, a small mountainous catchment located in north-west England,
and the Thames at Kingston, a large catchment with high levels of abstractions
located in south-east England. Results show a decrease in mean annual flow over
most of the UK, with negative median values of all monthly changes except in
winter over the western and northern mountainous areas. Furthermore the results
indicate a high likelihood of a significant decline in summer flows. Finally, an analysis
of variance showed that the major part of the uncertainty in river flow changes
comes from the spread in climate projections, with only 10% due to the hydrological
modelling.
Results are found to be quite consistent with the previous assessment based on individual
projections from 6 GCMs under the A2 scenario (Vidal & Wade, 2007) in terms of
overall decrease of central estimates and geographical split. The reduction in summer
low-flows—critical for water resources, especially in south-east England—appears however
more limited with UKCP09. Although most expected changes are within natural variability,
UKCP09 suggest drier hydrological conditions overall, and the spread of results is greater
than in previous assessments. Studies at the water resource zone and regional scales will now
be needed to derive implications for Deployable Output and to check the robustness of water
resource plans.
Murphy et al. (2009) UK Climate Projections Science Report: Climate change
projections. Met Office Hadley Centre, Exeter. ISBN 978-1-906360-02-3
Vidal & Wade (2007) Guidelines for resource assessment and UKWIR06 scenarios.
UKWIR report 06/CL/04/8. ISBN 1-84057-431-3
Christierson et al. (2009) Assessment of the significance to water resource
management plans of the UK Climate Projections 2009. UKWIR report
09/CL/04/11. ISBN 1-84057-547-6 |
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