Articles | Volume 20, issue 9
Hydrol. Earth Syst. Sci., 20, 3631–3650, 2016

Special issue: Panta Rhei: opinions and progress towards hydrology for a...

Hydrol. Earth Syst. Sci., 20, 3631–3650, 2016

Opinion article 08 Sep 2016

Opinion article | 08 Sep 2016

Drought in a human-modified world: reframing drought definitions, understanding, and analysis approaches

Anne F. Van Loon1, Kerstin Stahl2, Giuliano Di Baldassarre3, Julian Clark4, Sally Rangecroft1, Niko Wanders5, Tom Gleeson6, Albert I. J. M. Van Dijk7, Lena M. Tallaksen8, Jamie Hannaford9, Remko Uijlenhoet10, Adriaan J. Teuling10, David M. Hannah1, Justin Sheffield5, Mark Svoboda11, Boud Verbeiren12, Thorsten Wagener13,14, and Henny A. J. Van Lanen10 Anne F. Van Loon et al.
  • 1Water Science Research Group, School of Geography, Earth, and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
  • 2Hydrology Department, Faculty of Environment and Natural Resources, University of Freiburg, Freiburg, Germany
  • 3Department of Earth Sciences, Uppsala University, Uppsala, Sweden
  • 4Human Geography Research Group, School of Geography, Earth, and Environmental Sciences, University of Birmingham, Birmingham, UK
  • 5Civil and Environmental Engineering, Princeton University, Princeton, NJ, USA
  • 6Department of Civil Engineering, University of Victoria, Victoria, Canada
  • 7Fenner School of Environment & Society, the Australian National University, Canberra, Australia
  • 8Department of Geosciences, University of Oslo, Oslo, Norway
  • 9Centre for Ecology and Hydrology, Wallingford, UK
  • 10Hydrology and Quantitative Water Management group, Wageningen University, Wageningen, the Netherlands
  • 11National Drought Mitigation Center, University of Nebraska, Lincoln, NE, USA
  • 12Department of Hydrology and Hydraulic Engineering, Vrije Universiteit Brussel, Brussels, Belgium
  • 13Department of Civil Engineering, University of Bristol, Bristol, UK
  • 14Cabot Institute, University of Bristol, Bristol, UK

Abstract. In the current human-modified world, or Anthropocene, the state of water stores and fluxes has become dependent on human as well as natural processes. Water deficits (or droughts) are the result of a complex interaction between meteorological anomalies, land surface processes, and human inflows, outflows, and storage changes. Our current inability to adequately analyse and manage drought in many places points to gaps in our understanding and to inadequate data and tools. The Anthropocene requires a new framework for drought definitions and research. Drought definitions need to be revisited to explicitly include human processes driving and modifying soil moisture drought and hydrological drought development. We give recommendations for robust drought definitions to clarify timescales of drought and prevent confusion with related terms such as water scarcity and overexploitation. Additionally, our understanding and analysis of drought need to move from single driver to multiple drivers and from uni-directional to multi-directional. We identify research gaps and propose analysis approaches on (1) drivers, (2) modifiers, (3) impacts, (4) feedbacks, and (5) changing the baseline of drought in the Anthropocene. The most pressing research questions are related to the attribution of drought to its causes, to linking drought impacts to drought characteristics, and to societal adaptation and responses to drought. Example questions include

  • (i) What are the dominant drivers of drought in different parts of the world?

    (ii) How do human modifications of drought enhance or alleviate drought severity?

    (iii) How do impacts of drought depend on the physical characteristics of drought vs. the vulnerability of people or the environment?

    (iv) To what extent are physical and human drought processes coupled, and can feedback loops be identified and altered to lessen or mitigate drought?

    (v) How should we adapt our drought analysis to accommodate changes in the normal situation (i.e. what are considered normal or reference conditions) over time?

Answering these questions requires exploration of qualitative and quantitative data as well as mixed modelling approaches. The challenges related to drought research and management in the Anthropocene are not unique to drought, but do require urgent attention. We give recommendations drawn from the fields of flood research, ecology, water management, and water resources studies. The framework presented here provides a holistic view on drought in the Anthropocene, which will help improve management strategies for mitigating the severity and reducing the impacts of droughts in future.

Short summary
In the Anthropocene, drought cannot be viewed as a natural hazard independent of people. Drought can be alleviated or made worse by human activities and drought impacts are dependent on a myriad of factors. In this paper, we identify research gaps and suggest a framework that will allow us to adequately analyse and manage drought in the Anthropocene. We need to focus on attribution of drought to different drivers, linking drought to its impacts, and feedbacks between drought and society.