Robust estimates of climate-induced hydrological change in a temperate mountainous region
- 1.3k Downloads
A sustainable water resources management depends on sound information about the impacts of climate change. This information is, however, not easily derived because natural runoff variability interferes with the climate change signal. This study presents a procedure that leads to robust estimates of magnitude and Time Of Emergence (TOE) of climate-induced hydrological change that also account for the natural variability contained in the time series. Firstly, natural variability of 189 mesoscale catchments in Switzerland is sampled for 10 ENSEMBLES scenarios for the control (1984–2005) and two scenario periods (near future: 2025–2046, far future: 2074–2095) applying a bootstrap procedure. Then, the sampling distributions of mean monthly runoff are tested for significant differences with the Wilcoxon-Mann–Whitney test and for effect size with Cliff’s delta d. Finally, the TOE of a climate change induced hydrological change is determined when at least eight out of the ten hydrological projections significantly differ from natural variability. The results show that the TOE occurs in the near future period except for high-elevated catchments in late summer. The significant hydrological projections in the near future correspond, however, to only minor runoff changes. In the far future, hydrological change is statistically significant and runoff changes are substantial. Temperature change is the most important factor determining hydrological change in this mountainous region. Therefore, hydrological change depends strongly on a catchment’s mean elevation. Considering that the hydrological changes are predicted to be robust in the near future highlights the importance of accounting for these changes in water resources planning.
KeywordsClimate Scenario Future Period Hydrological Change Climate Change Signal Runoff Change
This study was funded by the Swiss Federal Office for the Environment (FOEN). The authors would like to thank the FOEN, the Swiss Federal Statistical Office (SFSO) and the Federal Office for Meteorology and Climatology (MeteoSwiss) for providing the necessary input data. The delta change scenario data were distributed by the Center for Climate Systems Modeling (C2SM). The data were derived from regional climate simulations of the EU FP6 Integrated Project ENSEMBLES (Contract number 505539) whose support is gratefully acknowledged. The dataset has been prepared by Thomas Bosshard at ETH Zurich, partly funded by swisselectric/Swiss Federal Office of Energy (SFOE) and CCHydro/Swiss Federal Office for the Environment (FOEN). The authors would like to thank Frank Paul and Andreas Linsbauer, Institute of Geography, University of Zurich (GIUZ), for providing the scenarios of glacier retreat.
- CH2011 (2011) Swiss Climate Change Scenarios CH2011. C2SM, MeteoSwiss, ETH, NCCR Climate, and OcCC, Zürich, Switzerland. http://data.c2sm.ethz.ch/dataset/ch2011/report/CH2011report.pdf. Accessed 15 September 2013
- FOEN (2012) Effects of Climate Change on Water Resources and Waters. Synthesis report on “Climate Change and Hydrology in Switzerland” (CCHydro) project. Federal Office for the Environment, Bern. Umwelt-Wissen No 1217. http://www.bafu.admin.ch/publikationen/publikation/01670/index.html?lang=en. Accessed 15 September 2013
- Giorgi F, Bi X (2009) Time of emergence (TOE) of GHG-forced precipitation change hot-spots. Geophys Res Lett 36(6), L06709Google Scholar
- Hänggi P (2011) Auswirkungen der hydroklimatischen Variabilität auf die Wasserkraftnutzung in der Schweiz,PhD Thesis, Faculty of Science, University of Bern,Berne, Switzerland, 206 pp.Google Scholar
- Hawkins E, Sutton R (2012) Time of emergence of climate signals. Geophys Res Lett 39(1), L01702Google Scholar
- Hegerl G, Zwiers FW, Braconnot P, Gillett N, Luo Y, Marengo Orsini J, Nicholls N, Penner J, Stott P (eds) (2007) Understanding and Attributing Climate Change. Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, CambridgeGoogle Scholar
- IPCC (2000) Emissions scenarios: A special report of IPCC Working Group III. Intergovernmental Panel on Climate Change, GenevaGoogle Scholar
- Merz B, Maurer T, Kaiser K (2012) Wie gut können wir vergangene und zukünftige Veränderungen des Wasserhaushalts quantifizieren?: How well can we quantify past and future changes of the water cycle? Hydrol Wasserbewirtsch 56(5):244–256Google Scholar
- Storch H, Zwiers FW (2001) Statistical analysis in climate research, 1st edn. Cambridge University Press, CambridgeGoogle Scholar
- van der Linden P, Mitchell J (2009) ENSEMBLES: Climate Change and its Impacts: Summary of research and results from the ENSEMBLES project, FitzRoy Road, Exeter EX1 3PB, UK. http://www.ensembles-eu.org/. Accessed 15 September 2013