Storing water has long been a cornerstone of socio-economic development, particularly for societies exposed to large climatic variability. Nature has always supplied the bulk of water storage on earth, but built storage has increased significantly, particularly over the 20th century. Today, numerous countries suffer from water storage gaps and increasingly variable precipitation, exacerbated by climate change. This is threatening to create greater barriers to sustainable development and even social stability. The need to develop more storage of all types (natural and built) – or at least manage current storage better – for resilient development is growing. At the same time, the policy, engineering, and scientific worlds may not fully recognize the extent of these storage gaps and how best to manage them. The costs and benefits of different types of storage can be both large and uncertain, and storage development can be risky and controversial. While the last decade has seen increasing consensus about the fundamental complementarity of built and natural storage, this has yet to translate into a pragmatic agenda to guide future water storage development.
Photos Credit: © IWMI
Today, there are numerous data gaps pertaining to water storage, as well as a need for greater clarity on some key concepts. It is important to recognize water storage as a service rather than only a facility. More than volumes of water stored behind a dam or in a watershed, what ultimately matters is the ability to provide different services at a particular time and place with a given level of assurance. In this way, integrated storage systems (drawing upon the strengths of different storage types – both surface water and groundwater) should be developed and managed to deliver targeted service standards. Such an integrated service perspective would reduce the costs – both direct and indirect - of new storage development, as well as make the benefits more sustainable.