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Thawing permafrost reduces river runoff, say Chinese researches

16.01.2012

Researchers at the Chengdu-based Institute of Mountain Hazards and Environment, part of the Chinese Academy of Sciences, have revealed that the amount of water entering the Yangtze River near its source on the Tibetan plateau has fallen by 15 percent over the past four decades, despite a 15 percent increase in glacial melt and increased rainfall over the same period. The research highlighted the complexity of permafrost hydrology and its importance as a headwater source. Researchers found that runoff increased if the 'active' ground layer — the part that freezes and thaws every year — was less than 60 centimetres deep, but decreased if the thaw went deeper. In degraded wetland with more of the permafrost thawed, runoff was up to 40 percent less than in healthy wetland.

Photo (c) Marshall Segal / Flickr