Global hydrological droughts in the 21st century under a changing hydrological regime

Abstract. Climate change very likely impacts future hydrological drought characteristics across the world. Here, we quantify the impact of climate change on future low flows and associated hydrological drought characteristics on a global scale using an alternative drought identification approach that considers adaptation to future changes in hydrological regime. The global hydrological model PCR-GLOBWB was used to simulate daily discharge at 0.5° globally for 1971–2099. The model was forced with CMIP5 climate projections taken from five global circulation models (GCMs) and four emission scenarios (representative concentration pathways, RCPs), from the Inter-Sectoral Impact Model Intercomparison Project. Drought events occur when discharge is below a threshold. The conventional variable threshold (VTM) was calculated by deriving the threshold from the period 1971–2000. The transient variable threshold (VTMt) is a non-stationary approach, where the threshold is based on the discharge values of the previous 30 years implying the threshold to vary every year during the 21st century. The VTMt adjusts to gradual changes in the hydrological regime as response to climate change. Results show a significant negative trend in the low flow regime over the 21st century for large parts of South America, southern Africa, Australia and the Mediterranean. In 40–52% of the world reduced low flows are projected, while increased low flows are found in the snow-dominated climates. In 27% of the global area both the drought duration and the deficit volume are expected to increase when applying the VTMt. However, this area will significantly increase to 62% when the VTM is applied. The mean global area in drought, with the VTMt, remains rather constant (11.7 to 13.4%), compared to the substantial increase when the VTM is applied (11.7 to 20%). The study illustrates that an alternative drought identification that considers adaptation to an altered hydrological regime has a substantial influence on future hydrological drought characteristics.

[1]  Arnold Eucken,et al.  Zahlenwerte und Funktionen aus Physik, Chemie, Astronomie, Geophysik und Technik , 1950 .

[2]  D. P. Stone.  The Intergovernmental Panel on Climate Change (IPCC) , 2015 .

[3]  Henrik Madsen,et al.  On the definition and modelling of streamflow drought duration and deficit volume , 1997 .

[4]  E. Wood,et al.  Projected changes in drought occurrence under future global warming from multi-model, multi-scenario, IPCC AR4 simulations , 2008 .

[5]  F. Ludwig,et al.  Vulnerability of US and European electricity supply to climate change , 2012 .

[6]  R. Uijlenhoet,et al.  How climate seasonality modifies drought duration and deficit , 2014 .

[7]  M. Bierkens,et al.  Global modeling of withdrawal, allocation and consumptive use of surface water and groundwater resources , 2013 .

[8]  P. Döll,et al.  A global hydrological model for deriving water availability indicators: model tuning and validation , 2003 .

[9]  M. Bierkens,et al.  Global depletion of groundwater resources , 2010 .

[10]  F. Piontek,et al.  A trend-preserving bias correction – the ISI-MIP approach , 2013 .

[11]  L. Tallaksen,et al.  Hydrological drought across the world: impact of climate and physical catchment structure , 2012 .

[12]  L. V. Beek,et al.  Human water consumption intensifies hydrological drought worldwide , 2012 .

[13]  Donald A. Wilhite,et al.  Drought : a global assessment , 2000 .

[14]  E. Wood,et al.  Drought: Past Problems and Future Scenarios , 2011 .

[15]  F. Piontek,et al.  The Inter-Sectoral Impact Model Intercomparison Project (ISI–MIP): Project framework , 2013, Proceedings of the National Academy of Sciences.

[16]  E. Martin,et al.  Evolution of spatio-temporal drought characteristics: validation, projections and effect of adaptation scenarios , 2012 .

[17]  E. Wood,et al.  Little change in global drought over the past 60 years , 2012, Nature.

[18]  A. Thomson,et al.  The representative concentration pathways: an overview , 2011 .

[19]  M. Bierkens,et al.  Nonsustainable groundwater sustaining irrigation: A global assessment , 2012 .

[20]  L. Tallaksen,et al.  Hydrological drought : processes and estimation methods for streamflow and groundwater , 2004 .

[21]  D. Easterling,et al.  Changes in climate extremes and their impacts on the natural physical environment , 2012 .

[22]  C. Prudhomme,et al.  Examining the spatio-temporal evolution and characteristics of large-scale European droughts , 2010 .

[23]  A. Dai.  Increasing drought under global warming in observations and models , 2013 .

[24]  V. Singh,et al.  The HBV model. , 1995 .

[25]  K. Bourzac.  Water: The flow of technology , 2013, Nature.

[26]  S. Seneviratne,et al.  Elusive drought: uncertainty in observed trends and short- and long-term CMIP5 projections , 2012 .

[27]  S. Hagemann,et al.  Hydrological droughts in the 21st century, hotspots and uncertainties from a global multimodel ensemble experiment , 2013, Proceedings of the National Academy of Sciences.

[28]  T. McKee,et al.  THE RELATIONSHIP OF DROUGHT FREQUENCY AND DURATION TO TIME SCALES , 1993 .

[29]  Russell S. Vose,et al.  The Definition of the Standard WMO Climate Normal: The Key to Deriving Alternative Climate Normals , 2011 .

[30]  N. Wanders,et al.  Future discharge drought across climate regions around the world modelled with a synthetic hydrological modelling approach forced by three general circulation models , 2013 .

[31]  R. Uijlenhoet,et al.  Identification of changes in hydrological drought characteristics from a multi-GCM driven ensemble constrained by observed discharge , 2014 .

[32]  Stefan Hagemann,et al.  Improving a subgrid runoff parameterization scheme for climate models by the use of high resolution data derived from satellite observations , 2003 .

[33]  S. Demuth,et al.  A global evaluation of streamflow drought characteristics , 2005 .

[34]  H.A.J. van Lanen,et al.  A process-based typology of hydrological drought , 2011 .

[35]  P. Jones,et al.  Global warming and changes in drought , 2014 .

[36]  M. Bierkens,et al.  Global monthly water stress: 1. Water balance and water availability , 2011 .

[37]  J. L. van Genderen,et al.  Drought: past problems and future scenarios , 2012, Int. J. Digit. Earth.

[38]  N. Wanders,et al.  Human and climate impacts on the 21st century hydrological drought , 2015 .

[39]  D. V. D. Leur.  Some effects of the unsaturated zone on nonsteady free‐surface groundwater flow as studied in a scaled granular model , 1962 .

[40]  N. Christidis,et al.  Modeling the Recent Evolution of Global Drought and Projections for the Twenty-First Century with the Hadley Centre Climate Model , 2006 .

[41]  L. Feyen,et al.  Ensemble projections of future streamflow droughts in Europe , 2013 .

[42]  J. Romm.  Desertification: The next dust bowl , 2011, Nature.

[43]  J. Palutikof,et al.  Climate change 2007 : impacts, adaptation and vulnerability , 2001 .