• Energy Research

Significance Our paper challenges the long-held view that the fall of Central Asia’s river civilizations was determined by warfare and the destruction of irrigation infrastructure during the Mongol invasion. An integration of radiometric dating of long-term river dynamics in the region with irrigation canal abandonment shows that periods of cultural decline correlate with drier conditions during multicentennial length periods when the North Atlantic Oscillation had mostly positive index values. There is no evidence that large-scale destruction of irrigation systems occurred during the Arab or Mongol invasion specifically. A more nuanced interpretation identifies chronic environmental challenges to floodwater farming over the last two millennia, punctuated by multicentennial-length periods with favorable hydromorphic and hydroclimatological conditions that enabled irrigation agriculturists to flourish.

Significance Our paper challenges the long-held view that the fall of Central Asia’s river civilizations was determined by warfare and the destruction of irrigation infrastructure during the Mongol invasion. An integration of radiometric dating of long-term river dynamics in the region with irrigation canal abandonment shows that periods of cultural decline correlate with drier conditions during multicentennial length periods when the North Atlantic Oscillation had mostly positive index values. There is no evidence that large-scale destruction of irrigation systems occurred during the Arab or Mongol invasion specifically. A more nuanced interpretation identifies chronic environmental challenges to floodwater farming over the last two millennia, punctuated by multicentennial-length periods with favorable hydromorphic and hydroclimatological conditions that enabled irrigation agriculturists to flourish.

Global warming-induced melting and thawing of the cryosphere are severely altering the volume and timing of water supplied from High Mountain Asia, adversely affecting downstream food and energy systems that are relied on by billions of people. The construction of more reservoirs designed to regulate streamflow and produce hydropower is a critical part of strategies for adapting to these changes. However, these projects are vulnerable to a complex set of interacting processes that are destabilizing landscapes throughout the region. Ranging in severity and the pace of change, these processes include glacial retreat and detachments, permafrost thaw and associated landslides, rock–ice avalanches, debris flows and outburst floods from glacial lakes and landslide-dammed lakes. The result is large amounts of sediment being mobilized that can fill up reservoirs, cause dam failure and degrade power turbines. Here we recommend forward-looking design and maintenance measures and sustainable sediment management solutions that can help transition towards climate change-resilient dams and reservoirs in High Mountain Asia, in large part based on improved monitoring and prediction of compound and cascading hazards.

Global warming-induced melting and thawing of the cryosphere are severely altering the volume and timing of water supplied from High Mountain Asia, adversely affecting downstream food and energy systems that are relied on by billions of people. The construction of more reservoirs designed to regulate streamflow and produce hydropower is a critical part of strategies for adapting to these changes. However, these projects are vulnerable to a complex set of interacting processes that are destabilizing landscapes throughout the region. Ranging in severity and the pace of change, these processes include glacial retreat and detachments, permafrost thaw and associated landslides, rock–ice avalanches, debris flows and outburst floods from glacial lakes and landslide-dammed lakes. The result is large amounts of sediment being mobilized that can fill up reservoirs, cause dam failure and degrade power turbines. Here we recommend forward-looking design and maintenance measures and sustainable sediment management solutions that can help transition towards climate change-resilient dams and reservoirs in High Mountain Asia, in large part based on improved monitoring and prediction of compound and cascading hazards.