More than half of the rivers on the planet dry up at least once a year

The new study is the first-ever empirically based attempt to quantify the global

distribution of intermittent rivers and streams.The map of intermittent freshwater sources resulting from this work, the first of its kind, also provides important baseline information for assessing future changes in streamflow intermittency. And to identify and monitor the role of these rivers and streams in global water and biochemical systems.

Rivers and streams that don't flow all year roundfound in all climates and on all continents, be it the snow-covered streams of the Himalayas, the wadi Sahara, which only occasionally fill with water, rivers a kilometer wide in the Indian subcontinent or small wooded streams of British Columbia. Credit: McGill University.

Continuous rivers and streams are very valuableecosystems because they are home to many different species that are adapted to the cycles of water presence and absence. In addition, these rivers are vital as sources of fresh, clean water and food for people. The authors of the study note that the problem is that more often than not, these resources are mismanaged or completely excluded as irrelevant when it comes to conservation laws.

Given the ongoing global climate and land use change, an increasingly significant portion of the global river network is expected to stop seasonal flow in the coming decades.

The study showed that many previously rivers andPerennial streams have dried up at least once a year over the past 50 years due to climate change, land use transitions, or temporary or permanent withdrawal of water for human and agricultural use. 

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