Landslides in Bhutan
Investigating the major at-risk roads in the Land of the Thunder Dragon in order to inform and provide insight through GIS
"Life is a highway... [and sometimes you CANNOT ride it all night long, or all day for that matter]." - Bhutanese Rascal Flatts
Before the 1960's, Bhutan's main method of transportation between villages and Dzongkhags consisted of foot travel and pack animal. However, the introduction of road networks have revolutionized the country's connectivity through rapid modernization. With these change of the times, this rural Kingdom in the Himalayas faces great challenges and risks from natural disasters closing roads and posing a threat to the wellbeing of the traveled.
Gross National Happiness
Our project falls primarily under the pillar of Good Governance. As Bhutan grows into a more developed country, Bhutan is making an effort to ensure that their growth is sustained and properly done for the good of all its citizens. Good Governance is cumulative effort of all four pillars and nine domains combined and if one section is lacking then it affects the society at large. Good Governance ensures that the government is doing its jobs to properly rule and help its citizens, including building and maintaining basic infrastructure such as the connecting roads linking the country as one. With basic upkeep and proper response protocols, landslides in Bhutan can become a more structured issue in line with GNH principles and Good Governance.
Landslides
Landslides have been and are prominent and devastating natural disasters in Bhutan due to its landscape and intense rainfall. The damage caused by landslides can be catastrophic causing significant loss of lives, damage to infrastructure, and loss of agricultural land. A study of a global database of landslide occurrences between 2004–2016 showed that 75% of landslides occurred in Asia, with significant occurrences in the Himalayan arc. The study also showed that the majority of the landslides are shallow landslides which are triggered by rainfall (4).
dzongkhags at risk of landslides
Top Six Landslides caught live on camera in Bhutan
Risks Factors for Landslides in Bhutan
Climate Change
Rising mean temperatures caused by climate change is the main cause for glacier retreat. The result is that glaciers in Bhutan are receding at a rate of almost 30-60 meters per decade. The melting ice from these receding glaciers is increasing the volume of water in glacial lakes, and the melting of ice-cored dams is destabilizing them, pushing the hazard risk for GLOFs to critical levels (1).
Earthquakes
The roar and shake of earthquakes throughout the Himalayas threaten the livelihood of all living in Bhutan due to the developments in valleys and high mountain passes.
Due to the effect of landslides, villages, cities, and roads can be easily destroyed, but not easily repaired. Without proper governance and materials, landslide clearnings can take up to weeks
Bhutan sits at the edge of the Indian and Eurasian continental plates leading to high risks of seismic activity inducing large landslides. The threat of a major earthquake poses a large risks to the management of roads and the transportation of all citizens in Bhutan.
Forest Fires
According to thinkhazard.org model there is greater than a 50% chance of weather that can support a significant wildfire that is likely to result in both life and property loss in any given year (2).
According to Kuensel a total of 16,214 acres of state forest reserve was lost in the year 2017-18 with 37 forest fire incidences in 12 dzongkhags. Of about 16,000 acres of forest lost last year, 10,000 acres of Blue Pine forest were lost to forest fires, followed by more than 6,000 Chir Pine forest (3).
Severe wildfires damage the forest canopy, as well as the soil which can result in increased runoff and major landslides.
River Flooding
Bhutan is also at risk from summer monsoons typically last from late June through to late September, at times causing flash floods and landslides; monsoons generate approximately 70 per cent of the annual rainfall in Bhutan (2).
Due to the high risk of flooding across all Dzongkhags, our analysis began with a focus on roads that have a close proximity in areas the tend to have the most rainfall each year.
Bhutan ranges in altitudes as high as 7000m in the Northern regions simulating an arctic climate and as low as 2500m in valleys which provide a rich tropical climate prime for monsoons (4). With this in consideration, we have focused on ranking our road risk priority from Southern roads to Northern Roads.
Slope Instability
As we all know from our awesome ride through the Trongsa roads, the slope of the roads in Bhutan can be quite extreme...
When looking at the stability of materials on slopes, 35 degrees to the normal allows for most materials to form a stable slope, yet anything greater with the addition of water results in a increase in downward movement (3).
Road Risk Analysis
In order to prepare a well thought out report of roads across Bhutan that are at risk from major landslides, criteria were placed to consider most "at-risk" roads during the analysis.
Criteria Considerations
- Major and minor roads
- Minor roads more prone due to less development
- Proximity to rivers = more slope
- Rainfall in Bhutan is much higher in South Bhutan
- Rank South to North for river flood risk
- Rank Dzongkhag risk for prioritization of infrastructure resources
GIS Steps Used to Find "At–Risk" Roads
- River buffer (100m)
- Intersect of Minor and Major Roads with River Buffer = Road segments near rivers
- Buffer of New Road Segments (50m)
- Reclassified slope data to give raster of points higher than 45 deg slope
- Raster to Polygon tool in prep of intersect
- Intersect slope polygons with road buffer to find risky roads
- Add geometry attributes using central point to get XY coordinates for each road segment
- Rank from smallest latitude to highest based on rainfall trends (higher in the south)
Results
Landslides in Bhutan
Conclusions
From our drawn analysis, we were able to spatially represent the most at-risk roads in Bhutan that are both close to rivers and on a sloped terrain greater 45 degrees. With the data given, these results are useful for identifying regions that are at a higher risk for potential landslides which can be used by the government to initiate routine check-ups on these "hot" locations. However, with extra data such as traffic density, travel statistics, and better rainfall data, this project can have the potential to provide accurate up-to-date road risk information to not just the government, but to those citizens that may be planning a road trip across Bhutan.
Useful Data to Have
- Travel statistics
- Traffic data
- Better rainfall data
- More detailed description of road types
- Emepheral road data
- Better Forest type data
- Earthquake risk data
Sources
(1) Islam, Faisal, and Hilary Hove. “Bhutan.” UNDP Climate Change Adaptation, 2011, www.adaptation-undp.org/explore/bhutan.
(2). “Landslide.” Think Hazard - Bhutan - Landslide, thinkhazard.org/en/report/31-bhutan/LS.
(3) kuensel1. “Fire Destroyed about 16,000 Acres of Forest Reserve in 2017-18.” KuenselOnline, KuenselOnline, 8 Aug. 2018, www.kuenselonline.com/fire-destroyed-about-16000-acres-of-forest-reserve-in-2017-18/.
(4) Bouali, El Hachemi. (2018). ANALYZING THE LIFE-CYCLE OF UNSTABLE SLOPES USING APPLIED REMOTE SENSING WITHIN AN ASSET MANAGEMENT FRAMEWORK.
(5) Oliver Sandoval
A huge thank you to the amazing people in this program and the fantastic RTC staff.
You all are the best.
Thanks for listening!
