Q: Could you assess the causes of landslides and flash floods in the northern mountainous provinces over the past few days

Dr. Nguyen Quoc Khanh: Most recent landslides in provinces like Cao Bang, Yen Bai, Lao Cai, and Bac Kan occurred in areas previously identified as high-risk in the state-funded landslide project (SFLP) for 'Investigation, assessment, and warning zonation for landslide in moutainous regions of Vietnam’. This project was handed over to local authorities by the Viet Nam Institute of Geosciences and Mineral Resources. 

Dr. Nguyen Quoc Khanh (left), Director of the Center for Remote Sensing and Geological Disasters, under the Vietnam Institute of Geosciences and Mineral Resources, speaking with the reporter from the Resource and Environment Magazine.

The causes of landslides and flash floods include geological, tectonic, topographic, and hydrometeorological factors, as well as human activities like deforestation, mining, and construction on mountain slopes. While rainfall remains the main natural trigger, human activities are increasingly adding to the risk. Climate change, particularly changes in rainfall patterns, is making landslides and flash floods more frequent, complex, and unpredictable, with greater destructive power, thereby significantly affecting the socio-economic landscape.

The state-funded landslide project (SFLP) for 'Investigation, assessment, and warning zonation for landslide in moutainous regions of Vietnam’, approved for implementation from 2012 to 2020, covers 37 provinces and cities, including Lai Chau, Dien Bien, Son La, Lao Cai, Yen Bai, Ha Giang, Lang Son, Cao Bang, Tuyen Quang, Bac Kan, Bac Giang, Quang Ninh, Hoa Binh, Thanh Hoa, Nghe An, Ha Tinh, Quang Binh, Quang Tri, Thua Thien Hue, Phu Tho, Vinh Phuc, Thai Nguyen, Da Nang, Quang Nam, Quang Ngai, Kon Tum, Gia Lai, Binh Dinh, Phu Yen, Khanh Hoa, Ninh Thuan, Binh Thuan, Dak Lak, Dak Nong, Lam Dong, Binh Phuoc, and Dong Nai, covering a total area of 261,789 square kilometers, with 104,500 square kilometers surveyed and 123,000 square kilometers mapped.

Q: Is it possible to have an early warning system for landslides and flash floods?

Dr. Nguyen Quoc Khanh: With advancements in science, technology, and information, early warnings for landslides and flash floods are entirely feasible. Globally, disaster early warning systems often involve multiple components, and early warning systems for landslides and flash floods are no different.

According to the United Nations International Strategy for Disaster Reduction, an effective early warning system consists of four key components: understanding disaster risk, monitoring and forecasting, disseminating information, and responding to landslide and flash flood disasters. Countries such as Japan, the United States, China, Taiwan, Hong Kong, and Thailand have already developed comprehensive systems incorporating these components.

In Vietnam, early warning technologies have made notable progress in certain agencies and localities. However, significant work remains to be done to bridge gaps in technology, information, and particularly communication and community education.

The state-funded landslide project (SFLP) for 'Investigation, assessment, and warning zonation for landslide in moutainous regions of Vietnam’ was approved for implementation over two phases: Phase I (2012-2015) focused on surveying and mapping at a scale of 1:50,000 for all 37 mountainous provinces, providing a foundation for more detailed surveys in Phase II. Phase II (2016-2020) included detailed surveys at larger scales in key areas identified in Phase I, with the installation of 10 pilot monitoring stations in key areas.

Q: As someone involved in the project, can you foresee the possibility of issuing landslide warnings for specific villages and key areas?

Dr. Nguyen Quoc Khanh: The state-funded landslide project (SFLP) for 'Investigation, assessment, and warning zonation for landslide in moutainous regions of Vietnam’ is a major undertaking, led by the Vietnam Institute of Geosciences and Mineral Resources. It was directed by Dr. Le Quoc Hung (2012-2017) and Dr. Trinh Xuan Hoa (2017-2021).

The zoning map for landslide risk warning shows dark red indicating very high risk and pink indicating high risk in Bao Yen district, Lao Cai province

Among the project's outputs are maps depicting landslide activity at scales of 1:50,000, 1:25,000, and 1:10,000, providing a clear picture of the current state of landslides and the factors contributing to their occurrence. There are also landslide hazard zoning maps at a scale of 1:50,000 (covering 15 provinces), presented on A0-sized sheets, accurate to the district (1:50,000 scale) and village level (key communes, 1:10,000 scale). Most of the recent landslide points in provinces like Cao Bang, Yen Bai, Lao Cai, and Bac Kan are listed as high-risk zones on these maps.

The zoning map for landslide risk warning shows dark red indicating very high risk and pink indicating high risk in Bac Ha and Si Ma Cai districts, Lao Cai province

Initially, the project was approved for 10 years, but due to various challenges, it was not extended and has now transitioned to the second phase ("Early warning of landslides and flash floods in Vietnam’s mountainous and mid-land regions"). After 10 years, only half of the original workload was completed. For instance, instead of mapping landslide activity at a scale of 1:50,000 for 37 provinces, only 25 provinces were mapped for current landslide activity, and 15 provinces for hazard zoning. The components related to risk, monitoring, early warning, and response have yet to be addressed.

However, the project's existing outputs are highly valuable, providing local authorities with a comprehensive view of landslide activity in their areas. The maps offer detailed information on individual locations where landslides have occurred and outline high-risk zones based on survey results.

The zoning map for landslide risk warning shows dark red indicating very high risk and pink indicating high risk in Yên Bai city, Yen Bai province

Local authorities and relevant agencies can use these maps as a preliminary warning tool, helping them assess the likelihood of recurring landslides in areas previously affected. The maps also serve as an early warning tool for new landslide occurrences in sensitive areas with similar natural and environmental conditions. Based on this information, localities can prepare appropriate response measures for each location, depending on the scale and risk of landslide occurrence during storm seasons.

Q: What solutions are needed to effectively warn of landslides and flash floods to minimize loss of life?

Dr. Nguyen Quoc Khanh: In recent years, research, surveying, evaluation, and proposing solutions to prevent landslides and flash floods have been carried out at various levels. Research institutes, universities, and specialized departments, such as the Department of Geology and Minerals, the Department of Meteorology and Hydrology, the Department of Climate Change, and the Department of Water Resources, have all contributed. The state-funded landslide project (SFLP) for 'Investigation, assessment, and warning zonation for landslide in moutainous regions of Vietnam’ is one such effort.

This project has provided important information, such as identifying high-risk areas and proposing suitable measures for prevention and risk mitigation. It has also suggested safe locations for emergency evacuations and resettlement sites, and delineated areas with different levels of landslide risk (very high, high, medium, low, very low).

Each year, the project's outputs are delivered to localities and relevant agencies, such as the General Department of Meteorology and Hydrology, the Department of Geology of Vietnam, the General Department of Disaster Prevention, and provincial disaster prevention and search and rescue committees. These contributions assist in forecasting, warning, and mitigating the impact of landslides and flash floods in Vietnam’s mountainous areas.

The zoning map for landslide risk warning shows dark red indicating very high risk and pink indicating high risk in Nguyen Binh district, Cao Bang province

However, to ensure effective warnings, an early warning system for landslides and flash floods must have all four components. Components 1 and 2 largely involve research and investigative agencies, while component 4 focuses on management agencies, local authorities, and communities. Component 3 requires coordination between these entities. Without any of these components, the system will fail. For instance, accurate warnings are useless if the public is unprepared or if the warnings are not effectively communicated by the relevant agencies.

Survey results have identified 12,099 potential landslide locations from remote sensing analysis and 14,726 confirmed landslide sites from field surveys in the 25 northern and central mountainous provinces. The provinces of Sơn La (1,791 points), Nghe An (1,347 points), Thanh Hoa (1,194 points), and Ha Giang (1,161 points) have the most confirmed landslide sites. However, the highest density of landslide sites relative to natural area is found in Hà Giang (0.146 points/km²), Thanh Hoa (0.145 points/km²), and Son La (0.127 points/km²).

Do Hung