Growing population and water demand have increased pressure on water resources in various parts of the globe, including many transboundary river basins. While the impacts of upstream water use on downstream water availability have been analysed in many of these international river basins, this has not been systematically done at the global scale using coherent and comparable datasets. In this study, we aim to assess the change in downstream water stress due to upstream water use in the world's transboundary river basins. Water stress was first calculated considering only local water use of each sub-basin based on country-basin mesh, then compared with the situation when upstream water use was subtracted from downstream water availability. We found that water stress was generally already high when considering only local water use, affecting 0.95–1.44 billion people or 33%–51% of the population in transboundary river basins. After accounting for upstream water use, stress level increased by at least 1 percentage-point for 30–65 sub-basins, affecting 0.29–1.13 billion people. Altogether 288 out of 298 middle-stream and downstream sub-basin areas experienced some change in stress level. Further, we assessed whether there is a link between increased water stress due to upstream water use and the number of conflictive and cooperative events in the transboundary river basins, as captured by two prominent databases. No direct relationship was found. This supports the argument that conflicts and cooperation events originate from a combination of different drivers, among which upstream-induced water stress may play a role. Our findings contribute to better understanding of upstream–downstream dynamics in water stress to help address water allocation problems.
Water and Development Research Group, Aalto University, Tietotie 1E, Espoo FI-02150, Finland;Water and Development Research Group, Aalto University, Tietotie 1E, Espoo FI-02150, Finland;Department of Geography, King’s College London, Strand, London WC2R 2LS, UK;Water and Development Research Group, Aalto University, Tietotie 1E, Espoo FI-02150, Finland;NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, USA;Center for Climate Systems Research, Columbia University, 2880 Broadway, New York, NY 10025, USA;Department of Physical Geography, Faculty of Geosciences, Utrecht University, Heidelberglaan 2, 3584 CS Utrecht, The Netherlands;Water and Development Research Group, Aalto University, Tietotie 1E, Espoo FI-02150, Finland
Recommended Citation:
H Munia,J H A Guillaume,N Mirumachi,et al. Water stress in global transboundary river basins: significance of upstream water use on downstream stress[J]. Environmental Research Letters,2016-01-01,11(1)