[Global Times Report Reporters Chen Zishuai and Shen Sheng] The rescue and rescue work for debris flow disasters in China and Nepal is still ongoing in an intense and orderly manner. The "8·26" debris flow disaster emergency rescue headquarters in Jilong County, Tibet Autonomous Region reported that as of 18:00 on September 5, the disaster had killed 43 people and left 519 people missing. According to news released by Nepal on the 7th, the bodies of 1,355 victims have been found in areas affected by mudslides in the country. "From what we learned on site, this disaster has very obvious characteristics of cross-border and chain disasters." Li Xin, deputy director of the Tibetan Plateau Institute of the Chinese Academy of Sciences, told the Global Times reporter that we cannot simply say which side of the disaster was "more severe." "To be more precise, the same cross-border disaster showed different disaster patterns under different terrains and different infrastructure conditions." A number of authoritative experts from China and Nepal were interviewed by a reporter from the Global Times on the 7th. They made a detailed analysis of the differences between the disaster situations in China and Nepal and the difficulties in rescue. They also put forward suggestions on how the two sides should strengthen disaster warning and strengthen response measures in the future. Basanta Raj Adhikari, an expert at Nepal's Tribhuvan University, said that a regional platform called the "Himalayan Monitoring Center" can be established, in which China, Nepal, Pakistan, India, Bhutan and other countries should participate.
How are disasters different?
On the morning of August 26, a glacier on the north slope of Langtanglirang Peak in Nepal broke off at an altitude of about 5,200 meters and caused an ice and rock avalanche. The high altitude quickly fell to about 4,000 meters, scouring the mountain and forming a giant mudslide. After impacting for about 22 kilometers, it reached my country's Geelong Port at an altitude of about 1,800 meters, causing about 0.7 square kilometers, 27 buildings and corresponding ancillary facilities in the area to be razed to the ground, and all roads, communications, and electricity leading to the Geelong Port were damaged and interrupted.
At the T-shaped intersection of the two river valleys of Gyirong Tsangpo and Donglin Tsangbo, the disaster fluid carrying boulders and sediment is split into two parts by virtue of its huge inertia: one countercurrent pours into the Gyirong Tsangbo Valley in China and rushes upward for nearly 3 kilometers along the G216 National Highway; the other flows along Donglin Zangbo and continues to rush towards the lower valley of Nepal, stretching for dozens of kilometers.
"The disaster was initially caused by the collapse of high-level glaciers in Nepal. The ice avalanche material quickly released, entraining a large amount of moraine, silt and rocks, and gradually evolved into high-speed debris flow and debris flow, and spread downstream along the river valley, ultimately causing serious impact on both sides of China and Nepal." Li Xin told the Global Times reporter on the 7th.
Li Xin further said that the disaster patterns in China and Nepal are different. The disaster on the Chinese side was relatively concentrated in the Jilong Port and its surrounding river valleys. It was characterized by a very sudden disaster and a very strong impact. Port facilities, roads, communications, electricity and other infrastructure were severely damaged. The Geelong Port itself is located in a high mountain canyon area, so the disaster caused a very strong impact in a relatively narrow space. On the Nepal side, it is more of a regional disaster that spreads downstream along the river valley. In addition to border areas, some villages and towns, markets, roads, bridges and hydropower projects have also been affected. In particular, after some hydropower stations and tunnels were hit by disasters, the tasks of personnel search and rescue and infrastructure repairs are more prominent.
Basantha Raj Adhikari, director of the Disaster Research Center of the College of Engineering of Tribhuvan University in Nepal, told the Global Times reporter on the 7th that the Chinese side, namely Gyirong, was severely affected and was relatively concentrated in areas close to the source and border crossings, "where the initial ice rock avalanches and mudslides had very high energy."
Rasuwa and Nuwakot districts are the hardest-hit areas in Nepal. Adhikari said that for Rasuwa County, the debris flow entered a steep and narrow valley. This terrain allows the debris flow to maintain a high flow rate and intensify the erosion of the river channel, while entraining sediment, boulders and debris in the river channel. The addition of these materials increases the size and destructive power of debris flows. As for Nuwakot district, as the valley widened, the flow velocity decreased, but the inundation and sedimentation spread over a larger area, affecting settlements, farmland and infrastructure.
What are the difficulties in rescue?
What are the difficulties in rescue at the Geelong Port? Mohan Bahadur Chand, a Himalayan glaciologist and assistant professor at Kathmandu University in Nepal, told the Global Times reporter that the narrow river valley and the buried infrastructure around the Gyirong Port made it very difficult to enter the relevant areas, carry out excavation work and confirm the identities of the victims. In addition, the slope is in an unstable state, which may cause secondary disasters to continue to occur.
Adhikari also believes that the destructive energy of the debris flow is concentrated in the narrow and steep Geelong Valley, and that search and rescue operations are very difficult due to unstable slopes, deep accumulations, rockfalls, and limited access conditions at the Geelong Port.
After seven days and nights of continuous repairs, the 3-kilometer rescue channel leading to the core area of the Geelong Port was basically opened on September 2. Relevant sources said that the construction area on site is extremely narrow, large machinery cannot operate at multiple points, in steps, and continuously, and there is insufficient space for equipment dispatch and turning and avoidance. "When the emergency repairs were the most difficult, they only advanced less than 5 meters in two hours."
What are the difficulties in rescue on the Nepal side? Chand said that in Nepal, the area affected by the disaster is larger. "This brings another series of problems. A large number of damaged bridges, roads, settlements and water and electricity facilities are distributed over dozens of kilometers. Therefore, rescue, tunnel operations, helicopters entering the disaster area and restoring transportation links need to be carried out simultaneously."
Adhikari said that in Rasuwa County, steep terrain and damaged roads and bridges may isolate some settlements and hydropower stations from the outside world, so rescues will need to rely on helicopters, local rescue teams and other means. In Nuwakot district, wider valleys spread floodwaters and debris over a wider area, resulting in a wider search area and more dispersed damage.
After the landslide disaster occurred, Chinese experts and rescue workers rushed to the aid of Nepal and worked closely with the Nepali side. According to relevant experts, residential buildings and engineering facilities along the river in Nigeria were seriously damaged, and on-site search and rescue work faced many challenges.
How can the two countries strengthen disaster early warning and response?
In the context of global warming, the internal structural stability of glaciers has declined and freeze-thaw cycles have intensified. Scientists generally believe that the frequency of ice collapses may further increase in the future. How can China and Nigeria strengthen disaster early warning and response in the future?
"It is essential to establish a formal network that directly connects various agencies engaged in disaster management and response work." Prakash Pokhrel, a geologist at Nepal's National Disaster Risk Reduction Administration, said in an interview with a reporter from the Global Times on the 7th that in order to reduce the growing risk of disasters as much as possible, Nepal's National Disaster Risk Reduction Administration is planning to establish a comprehensive early warning system and install various sensor facilities in areas prone to disaster events.
"Nepal and China should establish a real-time cross-border mountain disaster monitoring and data sharing system, which should include monitoring using satellites and drones, deploying seismic and ground sensors, monitoring glacial lake and river water levels, and automatically detecting major ice and rock mass instability." Chande told the Global Times reporter that the two countries should transmit early warning information across the border in a timely manner and conduct regular cross-border emergency drills.
"It is especially important that early warning systems must be able to cover rapid 'cascading disaster' events that only take a few minutes to form," Chand said. "Cascading disasters" refer to a disaster process that is triggered by one disaster and triggers a series of causally related disasters, forming a chain transmission and amplifying step by step.
Adhikari said that a regional platform called "Himalayan Monitoring Center" can be established. China, Nepal, India, Bhutan, Pakistan and other countries can jointly use seismic sensors, satellites, global navigation satellite systems and hydrometeorological monitoring networks to jointly monitor glaciers, unstable slopes, high-altitude lakes and river systems. "The center should realize cross-border real-time data sharing, establish unified risk thresholds and a rapid warning mechanism, so that ice and rock avalanches and cascading floods can be detected promptly by countries when they occur at the source, and evacuation and emergency response can be initiated before destructive mudslides reach downstream communities."
Su Pengcheng, a researcher at the Chengdu Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, said at a meeting with Chinese and foreign media held on the 6th that based on the actual situation of the Jilong Port, it is recommended that the following aspects of work can be strengthened in the future: First, strengthen the research on the disaster mechanism of cryosphere composite disaster chains such as cross-border ice and rock avalanches and debris flows in the Himalayas, and deepen the research, judgment and identification of early warning signals of disaster chains. Second, build an integrated air-space-ground non-contact monitoring system across the Himalayas to reduce reliance on field stations in extremely high-altitude source areas. Third, promote the construction of cross-border scientific research cooperation and early warning coordination mechanisms.
"China and Nepal should strengthen cross-border river basin joint disaster investigation, assessment, monitoring, and early warning, and establish an information and data sharing mechanism." Kang Shichang, director of the Chengdu Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, told a reporter from the Global Times on the 7th.
In an interview with a reporter from the Global Times, Li Xin said that in terms of data cooperation and sharing, China and Nepal have continued to cooperate since the early cataloging of glaciers and lakes in the Himalayas. "In the past few years, the National Tibetan Plateau Scientific Data Center and the International Comprehensive Mountain Development Center headquartered in Kathmandu, Nepal, have shared and interoperated some regional databases of the International Comprehensive Mountain Development Center. In future disaster relief, if there can be faster and more comprehensive data sharing, it should be beneficial to disaster prevention and reduction." In terms of disaster monitoring, Li Xin said: "In addition to jointly building a monitoring system, both parties should also establish a cross-border drone flight mechanism. Drones are a very important means in quickly responding to disasters."
Source: Global Times
