In October 2018, the Yarlung Zangpo River was blocked at Sedongpu Valley (N 29°44'54.29", E 94°56'17.71"). A barrier lake quickly formed and expanded, with floods ravaging nearby villages, farmlands and bridges.
An exploratory team of scientists led by Prof. YAO Tandong, TPE co-chair, arrived at the spot by helicopter, and found evidence of recent erosion and sliding at the nearby glacier as well as in the debris downstream. The team of scientists concluded that the blockage was triggered by an ice collapse in the upper part of the glacier. With immense force and speed, the ice collapse dragged debris down with it, all the way to the Yarlung Zangpo River. The debris then blocked the river.
After reviewing earlier records and satellite imagery of the area, the scientists found that a similar incident at the same spot occurred as early as 1984. In recent years, such incidents have become ever more frequent and devastating. The Yarlung Zangpo was also blocked in 2014 and 2017. The scientists believe that the general warmer and moister climate at the Third Pole has played a role in intensifying this type of disaster.
In response to this problem, Prof. YAO Tandong, who also leads the Second Tibetan Plateau Scientific Expedition and Research (STEP), proposed setting up an early warning system at the location. After discussion, a team of scientists decided to build a system that can monitor changes in the glacier, debris, water level and meteorological indices all in real time.
In November 2019, the first phase of the early warning system was put into operation. A monitoring tower was built at the Sedongpu Valley. The system takes pictures of the spot every three hours from various angles with cameras using infrared-enhanced vision that can see through darkness, fog, rain and even snow. Two radar water-level sensors and four weather stations are also installed in the vicinity to record water level and meteorological conditions in the area. The real-time data are transmitted via satellite to the STEP office for analysis, which enables scientists to warn of potential disaster at least three hours in advance. In fact, the system already sounded alerts for Sedongpu ice collapses in 2019.
The scientists are also planning to expand the monitoring program with a focus on disaster-prone sites within 20 km upstream as well as downstream. “This will allow us a fuller picture of the area for targeted early warning efforts and tailored policy-making,” said Prof. YAO. “With standardization, this can also be replicated in other disaster-prone areas.”
