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Building reservoirs leads to increases in long-term water use, resulting in prolonged periods of droughts and water shortages in downstream regions. This is concluded by a multidisciplinary team of ten drought scientists, including scientists from Utrecht ľ�ϸ���Ӱ��, in an article in Nature Sustainability. They recommend to put more effort into water conservation measures rather than in increased water supply.

The research team, including hydrologist Niko Wanders of Utrecht ľ�ϸ���Ӱ��, shows that the construction of dams and reservoirs is one of the most common approaches in coping with drought and water shortage. Even though this provides a solution for these problems, it can also have negative side-effects, explains Wanders. “An increasing water supply leads to higher water demand, which can quickly offset the initial benefits of reservoirs. This can result in a vicious cycle: a new water shortage can be addressed by further expansion of reservoir storage to increase water availability, which enables more water consumption, until the next shortage.”

The reservoir effect

The scientists call this vicious circle the ‘reservoir effect’, describing in which cases over-reliance on reservoirs increases the potential damage caused by drought and water shortage. The expansion of reservoirs often reduces incentives for preparedness and adaptive actions, thus increasing the negative impacts of water shortage.

Large-scale reservoir development over the last 100 years.

Water conservation measures

Attempts to increase water supply to cope with growing water demand, which is fueled by the increase in supply, is therefore unsustainable. Hence, the researchers recommend less reliance on large water infrastructure, such as dams and reservoirs, and more efforts to conserve water and reduce water consumption such as efficient drip irrigation. This reduces the local water consumption and thus the need for more reservoir storage in times of drought

Water use in the Netherlands

In the Netherlands per capita water use is high. The research findings suggest that building reservoirs in Germany and Switzerland to cope with drought in the Rhine, like this summer, is not a sustainable solution on the longer term. Wanders: “To really tackle the challenges of a changing climate with more droughts and water shortage we need to have structural measures to reduce Dutch water consumption.”

Publication

Di Baldassarre, G., Wanders, N., AghaKouchak, A., Kuil, L., Rangecroft, S., Veldkamp, T.I.E., Garcia, M., Van Oel, P.R., Breinl, K., and Van Loon A.F. (2018). . Nature Sustainability