Solution to prevent a repeat disaster in Nu Village

The information was shared by the research team of the University of Transport, University of Water Resources and University of Natural Sciences at the conference “Lup Village Disaster – causes and solutions”, held on January 2. 10, in Hanoi.

Associate Professor, Dr. Nguyen Lan Chau, University of Transport and Communications, said that his research team has surveyed and found many causes leading to the Lang Nu disaster and key areas in Lao Cai province. The main cause is the phenomenon of mud and rock floods – a type of combined flood including water, mud and rocks, capable of causing great destruction to construction works and causing important changes in the terrain. The characteristics of this phenomenon are the rapid conversion speed and large volume, often occurring after prolonged heavy rains in steep terrain

The research team also pointed out that the accumulated rainfall in the three days before Typhoon Yagi was too large, causing landslides of rocks and soil, which then accumulated into the narrow section, creating a temporary dam and breaking, leading to a massive flow of mud and rock. poured into Nu Village in the early morning of September 10, leveling 33 rooftops, killing 52 people. In addition to heavy rain, the shale geology is strongly weathered, the intensity is not high and the thick weather layer also increases the risk of landslides when exposed to rain.

“Rain water is the main factor causing landslides on terrain with weak geology,” Associate Professor Chau said. It is necessary to base on the rain threshold warning to assess the risk of landslides. If the rainfall is greater than 40 mm and the accumulated rainfall is > 250 mm, it can cause mud and rock floods.

He recommends that areas where cracks have formed should be covered with tarpaulin or plastic, and stapled down with steel to prevent water from continuing to seep into the cracks. At the same time, build a drainage system on high peaks and across slopes to prevent water from seeping directly into cracked areas.

Professor Do Minh Duc, Head of the Department of Geotechnics and Infrastructure Development, Faculty of Geology, University of Natural Sciences, Hanoi National University, and the research team proposed to build a detailed database. and establish a mapping system to identify high-risk areas. At the same time, establish a database of objects subject to natural and human-made impacts to assess the level of risk. Based on this database, build risk maps and scenarios, support management and control, and ensure safety against natural disaster risks on sloping lands.

Building an early warning system combined with regular monitoring of geological fluctuations is considered “very necessary” by scientists to minimize damage caused by mud and rock. Medium and long-term solutions include: prioritizing safety for concentrated population areas; Control negative impacts of rainwater and surface water; protect and develop forest resources; Building a comprehensive development plan for sloping lands… are also recommendations mentioned at the workshop.

Previously shared with VnExpressexperts also proposed many solutions to limit damage caused by natural disasters. MSc. Thai Ba Ngoc, expert in environmental geology, Ho Chi Minh City National University, said that preventing various types of geological disasters such as flash floods and landslides is a difficult problem, because of the topography of the areas. This area is very large with steep hills and mountains, making it impossible to build enough structures to cope.

Accordingly, in mountainous areas, it is necessary to localize and identify places with high risk of flash floods and landslides. With the geology industry, localities must determine the focus in a province, where the risk is high to monitor and warn people. It is necessary to research, analyze and determine the spatial distribution of terrain types, slope classification and geomorphological processes to clearly identify the main causes of each type of hazard, thereby serving as a basis for Zoning predicts the potential for stroke.

Mr. Ngoc proposed that in the coming time, it is necessary to build a monitoring system sufficient to cover points to warn of flash floods and landslides as well as a system of dams to prevent mud and rocks and auxiliary works. To implement monitoring solutions, pre-feasibility studies are needed such as carefully surveying the characteristics of geological structures, hydrogeology, and structures, clarifying whether there are active faults or not, and modeling and forecasting. Report areas at high risk of landslides. For projects in areas with high risk of landslides, it is necessary to cut drainage ditches on water sources flowing from the foot of the mountain to the road. At the same time, create many steps along the slopes and slopes of the road for appropriate design.

In the long term, Associate Professor Tran Le Luu, coordinator of the Master’s Program in Technology, Reuse and Water Management (Viet Duc University) believes that authorities need to do a good job in planning halfway houses. mountains and valleys. Do not build houses close to mountain slopes to prevent the risk of flash floods and landslides. It is necessary to plant forests to cover bare hills and mountains. Install gabions and iron mesh halfway up the mountain to prevent landslides and soil washing away. Before each stormy season, specialized agencies need to survey and assess the possibility of flash floods in the area they are in and have a plan to prepare for drills and evacuations when necessary.