New diagrams explain how humans affect water cycle

Representations of the Earth's water cycle used in textbooks throughout the world need to be updated, say scientists who have drawn up a new set of diagrams to include effects of human interference.

Leaving humans out of the picture contributes to a basic lack of awareness of how humans relate to water on Earth and a false sense of security about future availability of this essential and scarce resource, according to the study published in the journal Nature Geoscience.

The team from the University of Birmingham in the UK, Brigham Young University and Michigan State University in the US has drawn up a new set of diagrams to promote better understanding of how our water cycle works in the 21st century. These new diagrams show human interference in nearly all parts of the cycle. In a sample of more than 450 water cycle diagrams in textbooks, scientific literature and online, 85 per cent showed no human interaction at all with the water cycle, and only two per cent of the images made any attempt to connect the cycle with climate change or water pollution.

In addition, nearly all the examples studied depicted verdant landscapes, with mild climates and abundant freshwater usually with only a single river basin. The researchers argue there is an urgent need to challenge this misrepresentation and promote a more accurate and sophisticated understanding of the cycle and how it works in the 21st century

. This is crucial if society is to be able to achieve global solutions to the world's water crisis. "The water cycle diagram is a central icon of hydro science, but misrepresenting the ways in which humans have influenced this cycle diminishes our awareness of the looming global water crisis," said David Hannah, UNESCO Chair in Water Sciences at the University of Birmingham.