Climate change seems to be causing glaciers to retreat in Gansu province, bringing floods to local residents (Image: Chi-yuen Wang) As ice melts from glaciers in the region, lower lying land like that along the Silk Road floods (Image: Chi-yuen Wang)

The Chinese gateway to the ancient Silk Road is being flooded – and the culprit, researchers say, is climate change. Melting glaciers sitting above the Hexi corridor in Gansu province, once an important trading and military route into Central Asia, are fuelling dramatic regional floods.


The finding illustrates a major problem for the coming century: around the world, arid regions that sit next to glaciers will suffer a spate of floods, then dry up completely when the glaciers melt away.

Once the eastern gateway to the Silk road, the Hexi corridor is sandwiched between the Qilian mountains to the southwest, and lower mountains bordering the Gobi desert to the northeast.

“This is an extremely arid area, with an average annual precipitation of about 125 millimetres,” says Chi-Yuen Wang, a geologist and hydrologist at the University of California at Berkeley.

Frequent floods

Water scarcity has been less of a problem in recent years. Although irrigation pulled the region’s water table down during the 20th century, it unexpectedly began to rise again in 2003, and floods have been frequent since 2005.

By looking at the isotope composition of water in local springs, Wang and colleague Jian Sheng Chen of the hydrology lab of Hohai University in Nanjing, China, determined that most of this additional water seems to be coming from glaciers perched up in the surrounding mountains. This mixes with cyclic rainfall that largely stems from evaporation of the region’s irrigation water.

The fact that precipitation at high altitude has not increased significantly in recent years, means it is very likely that the extra water in the Hexi corridor has come from increased glacier melt, Wang told New Scientist.

Melting resource

Temperatures in Qilian mountains have risen by 0.04 °C per year on average since the 1980s and the glaciers have been creeping back up the mountain slopes, sometimes by as much as 7 metres in a single year. Melting permafrost makes it easier for the glacier water to seep into the water table and eventually make its way into the springs.

These springs have been supplying oases and the cities that were set up around them for millennia. The irrigation water they provide for agriculture has turned the Hexi corridor into a regional breadbasket. Some 26 million people live along the corridor and rely on the springs for water.

When the springs flood, they can wreak havoc on the unprepared region. The cities of Zhangye and Jiuquan have flooded repeatedly in the past few years, most severely in the winter, when irrigation stops and the water table rises. According to the researchers, the swelling springs have forced about 1000 families to evacuate.

The team says the situation is unlikely to improve. Most of the glaciers along the Hexi corridor are predicted to disappear by 2050, and, like other arid regions at the foot of melting glaciers, the area is in desperate need of creative new ways of managing its water supply (see Melting glaciers will trigger food shortages).

Journal reference: Geology (DOI: 10.1130/G25472A.1)