TIL BDR GHALLEY | Thimphu
Climate change, unstable terrain and development activities have heightened flood and landslide risks in Phuentsholing, with the recent disaster along the Amochhu River caused primarily by a massive natural landslide that discharged large volumes of debris rather than floodwater.
Minister for Infrastructure and Transport Chandra Bahadur Gurung said increasingly intense and frequent rainfall, driven by climate change, has significantly heightened the risk of floods and landslides in Phuentsholing, particularly along the Amochhu (Toorsa) River.
He said climate change remains the primary driver of the recent disasters, while development activities have contributed to localized flooding in some areas.
“The recent flooding in Phuentsholing has been attributed to both natural and manmade factors. The primary cause is climate-induced changes, particularly the increased intensity and frequency of rainfall, which have resulted in unprecedented landslides and significantly higher surface runoff.”
According to the minister, the recent disaster in the Amochhu area was caused mainly by a massive natural landslide rather than river flooding.
He said the event generated enormous volumes of debris, making it different from a conventional flood.
“The recent incident in the Amochhu area was predominantly caused by a massive landslide, resulting primarily in the discharge of large volumes of debris rather than floodwater.”
Preliminary investigations found no evidence that the landslide was triggered by human activities. Initial assessments also indicate that sediment deposits are exceptionally large and could continue to increase.
The minister said geotechnical studies show that much of Phuentsholing is highly susceptible to landslides. Studies on the Chamkuna hillside, next to the Amochhu Local Area Plan (LAP), found that about 80 percent of the area consists of inactive landslides that could be reactivated by even minor disturbances.
He added that although the Amochhu River has historically been prone to flooding, the risks have increased because of heavier rainfall in the upstream catchment.
As a result, the government is focusing on strengthening disaster preparedness while pursuing long-term mitigation measures.
River protection works completed under the Phuentsholing Township Development Project (PTDP) Zone A successfully reduced damage during the October floods last year, the minister said. However, he noted that PTDP Zone B remains inadequately protected and was severely affected during the same flooding.
The Department of Geology and Mines (DGM) has since begun river diversion through dredging and implemented emergency flood protection measures in the affected areas.
Meanwhile, local authorities are working with the National Centre for Hydrology and Meteorology (NCHM) to continuously monitor river levels and strengthen early warning systems for downstream communities.
The minister also identified Open Outfall 1, Outfall 3 and Outfall 5 as the three highest-risk locations among the 13 outfalls along the Amochhu and Chamkuna areas.
He said these sites have been included in a comprehensive risk and hazard assessment being carried out since 2025 under the Asian Development Bank-supported Building Adaptation and Resilience in the Hindu Kush Himalayas – Bhutan and Nepal project.
As part of long-term interventions, the ministry plans to strengthen regulations governing hillside development, particularly upstream construction activities that could increase landslide and flood risks.
“There is a need to strengthen policy and regulatory measures governing hillside development within the Dungkhag area, particularly by regulating upstream development activities to minimize landslide and flooding risks.”
The government is also considering establishing urban buffer zones along vulnerable hillsides above the Amochhu area.
To address recurring sediment accumulation, especially at the high-risk outfalls, the DGM is preparing a dedicated sediment management plan. While annual dredging has been effective in handling routine sediment deposits, the minister said the recent landslide has created an unprecedented volume of debris requiring a separate large-scale removal strategy after the monsoon.
The minister also said the existing bridge at Open Outfall 1 is no longer adequate for current conditions.
“The existing bridge was not designed to accommodate the magnitude of landslide-generated debris and flooding currently being experienced.”
He said a new bridge along the Phuentsholing–Samtse Highway would require a comprehensive catchment assessment to ensure it does not obstruct the natural flow of sediment during future disasters.
Looking ahead, the minister said future construction in vulnerable areas should adopt flood-resilient designs, including buildings with stilt floors and unoccupied ground levels, to reduce risks to life and property during extreme weather events.
