More than half of the 63 million km of rivers and streams on Earth periodically become completely shallow or even completely dry up during for of the year. Scientists came to this conclusion after conducting a global survey of aquifers in different parts of the world.
Rivers, which dry up partially or completely for part of the year, are most often found in dry regions, where evaporation is greater than precipitation. However, as it turned out, such temporarily sites can be found in all climatic zones and on all continents - from the Himalayan snow-covered streams and Saharan wadis to rivers half a mile wide in the Indian subcontinent. The longest river in the world, the Nile, has stretches that stop flowing from time to time, just like the majestic Indus and the Colorado River, and even in the Arctic, where rivers sometimes freeze, the same happens.
'Given continued global climate and land use change, an increasingly large proportion of the global river network is expected to cease to flow seasonally over the coming decades,' said Bernhard Lehner, one of the study's authors and a professor at McGill University in Montreal, Canada.
About 51 to 60 per cent of the 39million miles of rivers and streams on Earth stop flowing periodically, or run dry for part of the year, the researchers said.
Scientists used this data to create a first-of-its-kind map of volatile rivers. They hope this will help track future changes in river flow discontinuity and how these rivers and streams support biodiversity.
The study has been published in the journal Nature.
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