Warnaars, Tanya A.

English

NERC Open Research Archive

How the world’s water is changing from the 20th - 21st CDr. Tanya A. WarnaarsIntroduction Too often the knowledge of research scientists are underexploited because the culture and language used by research scientists arealien and often confusing to stakeholders.Data AvailabilityDrought and Climate Change: Are we seeing an increase in the frequency and severity of drought? If so what can we attribute it to? A key stop is to improve our process understanding of extreme events (Droughts and Floods). Basins in Europe have been selected which experience different climate and catchment control. - A near-natural dataset developed for examining trends in low flows and water   availability- Drying in the south and the summer; wetter in the north and the winter. - Models did capture broad patterns of temporal changeEnsemble mean for whole of EuropeObserved pattern from 426 catchments WATCH aimed to clarify the vulnerability of global water resources to climate change.  Its  data rich legacy that is publically available. Assessed for the first time the global water cycle on a daily timeframe for the 20th and 21st C. 20th C WATCH Forcing Data : 1901 – 2000 (a global 50 x 50 km grid)21st C WATCH Driving Data : 2001– 2100 (2scenarios, 3GCMs)Model output data for 20th and 21st CThe 20th C WATCH Forcing Data: 8 variables at the daily time-step for 1901-Water Model Intercomparison Project13 models used to generate global water balance estimates for the end of the 20th CResults show large variations in estimated global mean annual runoff values, with a range of nearly 30,000 km3 year-1, which will influence any impact study based on model simulation resultsA multi-model ensemble was compared to independent runoff observations from 426 small catchments in Europe1962-200420th C data(Griddedobservations)Simulated discharge/runoff time series (gridded)Global hydrological modelGCM 21st C runs(Griddedsimulations)Simulated discharge/runoff time series (gridded)Global hydrological modelData analyses (e.g. RDI)How well do large-scale models reproduce regional hydrological extremes in Europe?2001Conclusion: There is an urgent need to bring resent research findings to industry, stakeholders and other operations. Drought and Flood atlases corroborated for the 20th C are useful tool for understanding future change in length and severity of drought and flood events.The consequences  of changes to processes of precipitation and evaporation is higher localised rainfall (floods) or failure (droughts). These are 2 extremes of a range of expected changes, but frequency and location of these events are also dependent on feedbacks between climate and hydrological processes.Water scarcity is an issue facing many end-users and the tools for prediction and management need to be based on the most recent and relevant science available.The large spread contrasted by overall good performance of the ensemble meanChange in available water resources; comparison of end 20th C to end 21st C over selected large-scale catchments projected by an ensemble averaged for all 3 GCMsUp to 30% decrease forecast  for EuropeFuture Water Availability Proportion of area under drought:Days along bottom, years up side & colour-coded according to intensity:white = no drought in region purple = highly spatially coherent droughtCan immediately see very different drought  characteristics, between neighbouring regions or different models1988 - 9220052000199519901985198019751970196520052000199519901985198019751970196520052000199519901985198019751970196519842005200019951990198519801975197019651975 - 7620032004 - 06Jan     Mar   May   Jul      Sep     Nov Jan     Mar   May   Jul      Sep     NovSW Great BritainSE Great BritainGroundwater dominated

How the world’s water is changing from the 20th - 21st C

http://nora.nerc.ac.uk/18007/1/N018007PO.pdf

How the world’s water is changing from the 20th - 21st C

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