Climate change will probably cause landslides, said experts at a recent seminar on surveying, assessing and warning landslide dangers in Vietnam's mountainous regions.
Dr. Le Quoc Hung, the director of the Institute for Geological and Mineral Sciences, said that climate change is not something new, but a matter that has been directly affecting the environment and socioeconomic development of all nations worldwide, including Vietnam.
The fourth report of the Intergovernmental Panel on Climate Change (IPCC) emphasizes that climate change will lead to changes that increase extreme meteorological phenomena in terms of frequency, space and time. Research into climate change scenarios for Vietnam show that annual rain fall will increase in the late 21st century and it is expected to increase in the rainy season and decrease in the dry season, especially in southern regions.
According to the average scenario, rainfall in the late 21st century in Vietnam in general will be five percent more than in 1980-1999. According to the Ministry of Natural Resources and Environment's 2009 scenario on climate change and sea level rises in Vietnam, increase in rainfall in northern regions will be higher than that in southern regions. This indicates that climate change will probably increase the frequency of landslides and related risks.
Landslides are rather common in Vietnam's mountainous regions especially those located along newly constructed roads and roads that are being expanded or straightened. Landslides could leave roads buried under rock, threatening lives of people living along them and at the foot of the slopes.
There are many reasons for landslides, with the major causes being rain, soil and stone structure, and depleted forest coverage. Vietnam has a tropical monsoon climate that is associated with a high rainfall, floods and landslides. Many landslides in Vietnam are related to large rainfalls. In 1999, major rains and floods caused landslides in Quang Tri, Thua Thien Hue, Quang Nam, Quang Ngai and Binh Dinh provinces. Almost 40 people were buried under soil and stones, while hundreds of households had to move to other places. Quang Ngai Province alone had 3,400 hectares of cultivated land buried under stones and soil due to landslide. In June 2005, rains caused landslides along inter-district and inter-commune roads in Cao Bang Province. The landslide in Muong Vi in Bat Xat District in Lao Cai Province in 2010 killed one person, injured six others and swept away many houses and cereal crops.
Although there have been many projects researching landslide dangers in Vietnam's mountainous regions, landslides continue to happen without warning. A major reason for the lack of warning is the comprehensive lack of research on establishing a landslide warning system and maps of areas that are in a danger of being attacked by landslide.
Researching factors that could cause landslides, such as hydrometeorology in the context of climate change is also necessary. Resettlement is the optimal solution to avoid human casualties and loss of property. Developing a landslide prevention solution is vital after people living in the related area are removed because landslides can harm road users and farmers. Forecasting landslides remains important, and success in this regard depends much on considering the relation between hydrometeorology and other relevant factors in the concerned area.
Dr. Le Quoc Hung said that it is necessary to construct a consistent approach to landslide research, assessment and surveillance, apply appropriate, advanced methodology to evaluate the actual situation, find out reasons and give timely warnings about potential landslides to cater for planning activities and natural disaster control in the context of climate change.
Other seminar participants suggested analyzing conditions and factors that augur landslide in mountainous areas based on hydrometeorology surveillance data and landslides that have already happened in Vietnam.
It is important to construct detailed climate scenarios for each researched area and assess the impact of climate change on potential landslides in Vietnam's mountainous regions based on a future climate forecast model. Construction of a rain forecast model to assist landslide forecast is also important.