Our reporter Zhang Hailei and Gao Jianjun
At about 3:50 am on August 21, affected by the recent continuous heavy rainfall, a landslide occurred in Group 6 of Zhonghai Village, Fuquan Town, Hanyuan County, Ya'an City, Sichuan Province. The total volume was about 800,000 cubic meters, resulting in Provincial Highway 435. Traffic is interrupted. Seven people have died, and two missing persons are in search and rescue.
A mudslide occurred in Diaolinggou, Gokou Town, Maoxian County, Aba Prefecture on July 25, and houses on both sides of the ditch were washed away (photographed on August 5). Xinhua News Agency reporter Zhang Hailei
Located in the upper reaches of the Yangtze and Yellow Rivers, Sichuan is known as the "province of a thousand rivers". In the past month, several rounds of heavy rainfall have caused many rivers in Sichuan to be over-protected. The local government initiated Level I flood control emergency response on the 18th, the first time in records. Severe flood control situation coupled with unique topography and landforms, Sichuan mountain torrents and debris flow disasters occur frequently.
Due to the wide range of hidden danger points and large capital investment, in Sichuan, mountain torrent disasters face huge engineering management needs. Experts suggest that the level of technical defense should be improved, the relationship between flood control and ecological restoration should be coordinated, coordination between departments should be strengthened, and the defense system should be improved.
"After the evacuation was completed at 5:30, the debris flow came down at 5:40."
In front of the town government of Gokou Town, Maoxian County, Aba Tibetan and Qiang Autonomous Prefecture, Diaolingou flows to the Minjiang River, and the water is turbulent. The cordon raised reminds pedestrians of the thrilling scene that happened here not long ago.
"Thank you for ten minutes! All 80 households and 225 people were safely transferred." On the afternoon of July 24, Xu Maoqiao, a propagator from Gokou Town, received the weather warning information from the county and hurriedly gave it to the monitors in 7 villages in the jurisdiction. Make a phone call and send the information to the town and village cadres, and then send it to the villagers through the SMS platform to remind everyone to pay attention.
The rain kept falling that night. On the 25th, just after the day was polished, Xu Maoqiao went out to check, "The rain is getting heavier and louder, and there is a rumbling sound from the ditch." Realizing that it may be a mudslide, she and other personnel on duty divided into several routes, knocking on the gong, Shout the horn to let the villagers near Diaolingou move quickly.
"The evacuation was completed at 5:30, and the debris flow was down at 5:40." Xu Maoqiao recalled that the swift flood, with sand, rocks and other debris kept rushing down, the revetment was also eroded by the flood. , Washed out.
Due to the timely transfer, except for 8 houses and part of the river that were destroyed, none of the villagers in Changan Village near Diaolingou were injured or killed.
Sichuan is one of the provinces with the most severe flash flood disasters in the country. There are 3,172 rivers with flood control tasks in the province, and 28,156 flash flood hazard areas. Of the 480,000 square kilometers of land area, 380,000 square kilometers are flash flood prevention and control areas; out of 183 county-level administrative regions, 175 have flash flood prevention and control tasks.
Tan Xiaoping, deputy commander of the Sichuan Flood Control and Drought Relief Headquarters and deputy director of the Sichuan Provincial Water Resources Department, introduced that after the May 12 earthquake, the Ya’an earthquake, and the Jiuzhaigou earthquake, many mountains were shaken loose, and there were abundant sources in the ditch. Heavy rainfall, flash floods and mudslides often occur simultaneously.
"In addition to the heavy rainfall during the flood season, the floods are violent, with steep ups and downs. The time from rainfall to flash flood disaster formation is short and the disaster occurs quickly." Tan Xiaoping told reporters.
When the reporter traveled along National Highway 213, he repeatedly saw gravel washed down by rain and traffic jams caused by it. In some sections of the road, the reporter got out of the car and broke the stones with his hands, and the sand immediately rolled off. As of August 15 this year, Aba Prefecture alone has had 132 large and small landslides.
Mountain torrents and mudslides often cause huge economic losses. In Kekezhai Village, Fengyi Town, Mao County, the villager Liang Weikang’s home is more than 100 meters away from Kekezhai Gully. When a mudslide happened on July 25, the water instantly rose to his chest. Before he and his family could transfer the supplies, he hurried to the second floor. After the mud and rocks flowed, the first floor was completely flooded, "the silt is 80 cm thick".
The reporter saw that a large number of rocks were piled up at the mouth of the mountain flood ditch that runs through the village, including stones the size of an excavator. Part of the sand and gravel flowed into the Minjiang River, causing the river to narrow and the water level to rise. According to statistics, as many as 400,000 cubic meters of sand and gravel were washed away by the flash flood.
Deng Xiwu, secretary of the Party branch of Kekezhai Village, said that the flood disaster also destroyed more than 1,000 acres of land in the village, as well as several pig farms and fish farms. The running water system in the village was interrupted and the direct and indirect economic loss was 15 million yuan.
"Fortunately, a section of the embankment played a role, and the mudslide has not been diverted, otherwise the consequences will be disastrous." Deng Xiwu said that once it turns, more than 300 people in the 80 households below will face a huge threat.
The diversion of the river has brought painful experiences. On the evening of June 26, a torrential rain made Caoguhe a "nightmare" in Damawu Village, Yihai Town, Mianning County, Liangshan Prefecture-a steady stream of floods, mixed with rocks, sand, and branches, drove to the village. Rageous, a mess wherever he went.
There are more than 3000 mountain torrents and gullies in the province, of which only 88 have undergone engineering treatment
At present, the prevention and control of mountain torrent disasters are mainly non-engineering measures such as investigation and evaluation, monitoring and early warning, group monitoring and prevention, and engineering measures such as construction of dikes and bank protection.
In 2010, my country initiated the construction of county-level non-engineering measures for mountain flood disaster prevention and control, and gradually established a monitoring and early warning system and a mass monitoring and prevention system.
In Sichuan, there are rainfall stations, water level stations and other monitoring equipment located downstream of many mountain torrent ditches. The data they collect are automatically transmitted to the mountain torrent disaster early warning system of each county. Once the data is found to exceed the normal value, village and town cadres and monitors will notify and organize the transfer of the masses.
In Yinjia Village, Duoying Town, Yucheng District, Ya'an City, there are evacuation route indication arrows and transfer route signs hung in several prominent locations in the village. The sign indicates the scope of transfer, the person responsible and the contact number. Follow the arrow to walk to the Yinjia Village Committee.
"There is also a transfer and evacuation map on the walls of the villagers' homes. They are simple and clear. Everyone knows where to go." Yin Pingfu, deputy director of Yinjia Village, said.
However, mountain torrent geological disasters are concealed and sudden. In some places, rainfall reaches a critical value and then begins to shift, which may not be too late. Tan Xiaoping introduced that in extremely high-risk areas, Sichuan adopts the "forecast transfer" method. When the weather forecasts are released, personnel in these areas are required to move in advance. "Although the rain may not start at that time, it must be avoided by measures. Try to ensure the safety of personnel."
During the interview, grassroots water conservancy cadres and staff generally reported to reporters that the management of mountain torrents and mudslides and geological disasters requires the cooperation of non-engineering measures and engineering measures to achieve the greatest effect. "But the reality is that the construction of river banks and other engineering measures is relatively lacking. , So that the effect of disaster prevention and mitigation is greatly reduced."
Currently, the construction of engineering measures is facing a huge funding gap. It is understood that if the construction standard for the construction of a one-kilometer dike is a flood once every ten years, an investment of about 5 million yuan is required, and many places can only be constructed in stages. There are more than 3,000 mountain torrents in Sichuan, but in view of the funds obtained, only 88 of them have been treated.
According to reports, the provinces generally consider the severity of hidden dangers, the annual disaster situation, and the difficulty of governance to obtain and allocate funds for the projects reported by various cities and prefectures.
On August 20, 2019, affected by heavy rainfall, torrents and mudslides occurred in many places in Wenchuan County. After nearly a year, the reporter saw in Banzigou, Mianlou Town, that the rocks washed by the mudslide last year piled up like hills along the river. More than 700 acres of arable land and woodland are still uncultivated.
This first-level tributary on the right bank of the upper reaches of the Minjiang River is more than 15 kilometers long with a drop of 3,730 meters. “Last year, mudslides caused the Minjiang River to be diverted and the highway was interrupted,” said Mao Xu, director of the Wenchuan County Water Affairs Bureau. “However, due to lack of funds, only the dredging of the river has been completed.”
In addition to Banzigou, there are Dengxigou, Caopogou, and Tuotougou in Mianluo Town. Last year's flash flood and mudslide disaster caused nearly 10,000 people in 17 villages in the town to be affected.
"After the disaster, we declared a flood control project worth nearly 100 million yuan to the province, and the final flood control project approved was only about 33 million yuan." Mao Xu said, "It is understandable that every county has mountain torrents to be harnessed. , But the big plate has so much funds, and the province must also be considered as a whole."
"Where is the hidden danger" and "When will it happen" are still two major problems
The grassroots water conservancy departments and experts said that in response to the characteristics of Sichuan floods and geological disasters, the level of technical prevention should be improved, and the coordination of water conservancy, natural resources, forestry and grass and other departments should be strengthened to improve the defense system.
In Sichuan, the disaster points of mountain torrents and debris flows are wide-ranging, concealed, difficult to identify, and the ability of monitoring and early warning personnel varies. In addition, most of the small mountain torrents upstream are in high mountain valleys. There is no signal, no electricity, and few monitoring equipment. In addition, many of the installed monitoring equipment is seriously aging, "Where is the hidden danger" and "When will it happen?" There are still two major problems.
Mao Xu and other grassroots cadres believe that in addition to strengthening "civil air defense", we should also improve technical and intelligent defense capabilities, such as strengthening the construction of intelligent rainfall monitoring stations in unmanned areas, introducing professional teams and technologies, and realizing dynamic changes on the surface of hidden danger points. Monitoring etc.
In the engineering measures for the treatment of mountain torrents and gullies, the barrier dam built by the natural resources department can intercept the trees, rocks and other solid materials that are washed away during the flash flood, and prevent the channel siltation and the blockage of bridges and culverts from affecting flood discharge. The dikes and bank revetments that the water conservancy department is responsible for can reduce the damage to the river course by floods and try to let the flood flow along the river course.
In the case of limited construction funds, how to cooperate with relevant departments to maximize the governance effect has become a key consideration.
Although there is no corresponding mechanism yet, the Wenchuan County Water Affairs Bureau and the Natural Resources Bureau have begun to explore this issue on the basis of daily flood information sharing.
Yanmengou in the county experienced several flash floods and mudslide disasters on July 10, 2013 and August 20, 2019. Last year, the water department did not apply for funds for the management of the mountain torrent ditch. After the construction of the dam, the Bureau of Natural Resources coordinated the repair of a dike of about 800 meters, which made up for the construction gap to a certain extent.
"Although they are different departments, the purpose is the same, they are disaster prevention and mitigation." said Chen Daijun, director of the Wenchuan County Natural Resources Bureau.
In addition, the grassroots personnel believe that effective management of mountain torrents must be constructed from the perspective of restoring mountain vegetation and preventing soil erosion.
After the Wenchuan earthquake, Sichuan initiated the "Forestry Management" Forest Vegetation Recovery Project after the earthquake through international cooperation. The project adopts the concept and model of “reinforce the mountain before afforestation” to comprehensively restore the fragile ecology, that is, to stabilize the mountain geological disasters through engineering measures to carry out “mountain control”, and to use engineering biological measures to control water and soil erosion to “fix soil”. The modern afforestation and vegetation restoration project has completed the "green planting", and the flood control and flood control projects have been built to conserve forest land to achieve "water conservation". After several years of development, these "forestry management" projects have withstood the test of mudslides and earthquakes.
Yan Wuxian, director of the Forestry Research Institute of the Sichuan Academy of Forestry, believes that for mountainous areas, a batch of comprehensive management projects that combine biological and engineering measures should be planned first, and secondly, a collaborative communication mechanism should be established to change the current industrialization and sectoralization of different departments. The status quo of modernization, "combination boxing."