KATHMANDU, Sept 10: The flood that entered the Trishuli River from Tibet through the Bhotekoshi River on August 26 swept away 41 bridges and damaged three others. Of the 63 bridges along the flood-affected stretch from Rasuwagadhi to Muglin, only 19 survived.
The flood swept away even permanent bridges built with modern designs. Some have disappeared completely. The Department of Roads has prepared a preliminary report on the damage.
The flood reached heights and flow speeds far beyond what the bridges were designed to withstand. Experts say the unusually high and fast flow swept away some bridges in a single blow. The flood carried not only water but also huge rocks, gravel and mud, making it easier to destroy bridge structures.
“Only bridges built well above the roads along the river survived. Bridges that stood only slightly above the river level were all swept away,” said Dr Bijay Jaisi, director general of the Department of Roads. “Future bridges will have to be built much higher above the river level.”
Experts say bridge designs must now be revised, particularly for risky locations and streams in mountainous areas.
Where bridges survived and where they collapsed
According to the Department of Roads’ field technical report, 41 of the 63 bridges across the Bhotekoshi and Trishuli river areas were swept away, while three suffered structural damage. Nineteen survived. The report says the flood devastated the national highway, regarded as a major trade lifeline with China, as well as local feeder roads.
The road connecting Betrawati in Rasuwa through Mailung, Syafrubesi and Rasuwagadhi has been completely damaged. Around 40 kilometres of road in Rasuwa alone have been destroyed. The strategic section had 63 bridges: 53 under the Department of Roads and 10 built by private hydropower projects and local governments.
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Of the 53 bridges under the department, 32 were swept away, three were damaged and 18 survived. Of the 10 bridges built by hydropower projects and other agencies, nine were completely swept away, and one survived. Rasuwa was the worst affected district, with 22 of its 27 bridges washed away.
The Miteri Bridge at Rasuwagadhi, which links Nepal and China, was completely swept away, leaving cross-border trade through the northern route uncertain. Both the Timure 1 and Timure 2 Bailey bridges in Rasuwa’s Timure area were also washed away.
The 40-metre Ghatte Khola, 30-metre Phenlung and 20-metre Kulong permanent bridges along the national highway were swept away by the powerful current. The Bhotekoshi permanent bridge at Chilime and the 100-metre Runga Khola bridge at Chilime were also destroyed.
The Bailey bridge serving a hydropower project at Syabrubesi and the 86-metre permanent Syafrubesi bridge, a key link for local transport, were also swept away, completely cutting off access to upper areas.
Flooding also damaged access structures built by private companies and hydropower projects. The Bailey bridge at Audit 1 of the 216 MW Trishuli project, both Bailey bridges at Haku 1 and Haku 2, the Bailey bridge of the Upper Trishuli Hydropower Project and the Bailey bridge at Mailung Bazaar were swept away.
The 35-metre Haku Khola bridge, the 40-metre Bimli Khola bridge, the 10-metre Crossing 0+700 bridge, 60-metre Mailung Chipleti steel arch bridge, and two bridges at the Trishuli 3A dam and the 25-metre Bahubali Jharana bridge, all under the Department of Roads, were also swept away.
The condition of five surviving bridges in Rasuwa was confirmed through aerial inspection because inspectors could not reach them by road.
The aerial inspection found the 20-metre Sano Bharkhu RCC bridge, 15-metre Thulo Bharkhu RCC bridge, 20-metre Trishuli Khola prestressed bridge and 35-metre Thade Khola prestressed bridge intact. The 10-metre Thado Khola bridge at Chainage 50+300 also survived.
Of the 22 bridges in the Rasuwa-Nuwakot border area and Nuwakot district, 15 were swept away, one was damaged after being buried and six survived.
The 50-metre New Steel Arch Bridge at Khalte, linking the two districts, was swept away. Both the 70-metre old and new permanent bridges at Betrawati collapsed under the force of the flood.
In the Nuwakot section, the 100-metre Trishuli River bridge at Tupche, both the old and new 60-metre permanent bridges at Trishuli Bazaar, and the 100-metre Trishuli bridge at Simchaur were completely swept away.
The Trishuli River bridge near Devighat along the Mid Hill Highway, both the old and new 55-metre Tandi Khola bridges at Devighat, and the suspension bridge near the Water Resources and Irrigation Division office at Devighat were also swept away.
Other bridges destroyed in Nuwakot included the 180-metre Trishuli bridge along the Khadg Bhanjyang Shrikhali road, the 140-metre Buddhasinghat bridge, the 150-metre Ratmate bridge and the Trishuli River bridge at Kewrini Phosretar.
The 20-metre Thulo Khola prestressed bridge at chainage 13+260 was buried by the flood. RCC and prestressed bridges over Sukhaure Khola, Dhobi Khola, Gundre Khola, Bire Khola, Gerukhu Khola and Jhangar Khola in this section survived.
Of the 11 bridges in Dhading, five were swept away, two were damaged and four survived. The 150-metre bridge linking Baireni Syaltar road below Galchhi, the 120-metre Jarebagaincha bridge, the 200-metre Ghatbesi bridge and the 118-metre Furke Khola Trishuli bridge at Malekhu were swept away.
Both the old and new bridges over Kolpu Khola in Dhading were damaged. In particular, the new 40-metre prestressed bridge at chainage 2+520 was shifted downstream from its original foundation by the force of the flood.
Although its foundation has shifted, the bridge is still operating under risky conditions.
The Trishuli bridge along the Bhimdhunga Lamidanda road, the Mahesh Khola bridge, the Mastar Trishuli bridge, Benighat bridge and the bridge linking Fisling and Gorkha in Dhading survived.
Bridges downstream in Chitwan were spared. All three bridges in the Chitwan section remain safe. The Bailey bridge at the Trishuli Hydropower Project in Chumlingtar, the 160-metre modern Muglin Arch Bridge and the old Muglin suspension bridge were not affected.
By bridge type, Bailey bridges proved the most vulnerable. Of the 10 Bailey bridges listed in the report, nine were swept away, with only the one at Chumlingtar in Chitwan surviving.
The modern steel arch bridges at Mailung Chipleti and Khalte, built to cross the river, also collapsed under the force of the flood. Small RCC and prestressed bridges over tributary streams survived, but the flood swept away long-span permanent bridges over the main rivers.
The complete disruption of the northern trade route through Rasuwagadhi, combined with the destruction of the Galchhi Syafrubesi road, has dealt a major blow to supplies, daily life and the hydropower sector.
