This year, unlike in the past, the Government of Nepal’s prudence was evident when the Department of Hydrology and Meteorology (DHM) issued heavy rainfall warnings. The National Disaster Risk Reduction and Management Authority (NDRRMA) issued a four-day travel advisory for October 3–6, which prohibited long-distance vehicle operations and limited travel in susceptible areas. Citizens were urged to refrain from avoidable travel with early warnings of landslides and swelling rivers in the provinces of Koshi, Bagmati, Gandaki and Lumbini. Even public holidays were issued for two days, prompting the residents to stay safely at home.
With swift evacuations and well-coordinated communication, these preventative measures helped prevent significant losses during the monsoon. A slight improvement in Nepal’s disaster management was visible this year, evident with better early warning systems, institutional coordination and a maturing public response mechanism. Yet, early preparedness and rapid post-disaster recovery can no longer remain the only answer: infrastructures built for a gentler historical climate remain worryingly defenseless to the “new normal” of intensifying future extremes.
The flood that rewrote the map
The September 2024 floods were a sobering lesson. A rare cyclonic circulation and mid-tropospheric westerly trough triggered 60 hours of continuous rainfall across central and eastern Nepal. According to the Department of Hydrology and Meteorology, over 183 weather stations recorded more than 50 mm, while 25 broke 24-hour records, some exceeding 400 mm. The streams of the Bagmati, Koshi, and Narayani basins surpassed their historic highs, causing landslides, debris flows, and flash floods that affected 2.6m people, claimed 249 lives, and caused economic losses exceeding Rs 46bn, over one percent of GDP.
Among the worst hit was the Banepa–Bardibas (BP) Highway, a lifeline connecting Kathmandu with the eastern Tarai. Field assessments along the Roshi Khola corridor, from Bhakunde Besi to the Sunkoshi confluence, revealed widespread destruction, with dozens of landslides and slope failures damaging approximately 80 km of the highway, and 26 km were severely impacted. Collapsed retaining walls and eroded embankments were anything but sparse. In one particularly devastated stretch of the Kavrepalanchok district, the river eroded an 8-km segment of the roadway, rendering it impassable.
Our study found that the Roshi basin received an average of 267 mm of rainfall in 24 hours, equivalent to a once-in-773-year event, based on 60 years of rainfall records. The unprecedented precipitation turned the river into a force that the infrastructure was never built to face, with a discharge significantly higher than the design capacity.
A year later, the same story
The susceptibility was exposed again this year. Temporary repairs failed, embankments slumped and diversions were washed out. The BP Highway’s recurring damage reveals a systemic flaw: Nepal’s highways, particularly along river corridors, are no longer safe, acutely exposed to the whims of climate extremities.
Lessons from collapse
First, our engineering standards must evolve. The flood magnitudes adopted by the NRS 2070 assume a 50-year return period for first-class roads and a 100-year for bridges. While a 10 percent increase in design discharge is mandated to account for climate change, DOR’s Guidelines on Hydrologic and Hydraulic Analysis and River Training Works for Bridge Design no longer suffices in the face of rapidly shortening return periods.
There should be no delay in increasing the design return period to 100 and 200 years for major roads and bridges, respectively. Moving beyond reliance on historical data-based frequency analysis, all major road retrofitting, bridge reconstruction and new construction projects must be checked against the contemporary climate projections for the design period.
Second, planning must be risk-informed and data-driven. Integrating climate-informed vulnerability mapping to identify at-risk zones before the construction or repair is imperative. This helps to avoid the high-risk zones from the get-go and minimizes the likelihood of recurring future damage.
In flood-prone river corridors, vulnerability mapping determines where infrastructure elevation is necessary versus where an early warning system might suffice (reducing consequence through evacuation and traffic management). This systematic approach should be an indispensable first step before deploying costly engineering solutions.
And most importantly, resilience cannot rely on concrete alone. Structural adaptations like increased freeboard of bridges and strategic elevation of roadways should be complemented with nature-based and hybrid solutions, vegetative slope stabilization and bioengineering. In Nepal, steep slopes could benefit particularly from hybrid approaches such as vegetative bioengineering combined with check dams. Also, land-use planning, like establishing conservation buffer zones adjacent to floodplains to regulate development, prevents encroachments that heighten flood levels or exacerbate erosion.
Reaction to resilience
To break free from the disaster and repair loop, Nepal must embed “climate logic” into its development DNA. “Fund Resilience, Not Disasters,” the theme from the recent International Day for Disaster Risk Reduction, captures this urgency: invest now, or pay exponentially later.
Short-term restoration of strategically important corridors like the BP Highway must go concurrently with long-term resilience planning. Roads should be realigned away from unstable river bends where possible, with major corridors upgraded for at least 100-year floods, and slope protection integrated with river training works such as spurs and check structures.
Design standards must evolve beyond the historical averages to incorporate the plausible future scenarios. Climate risk screening and cost-benefit justification for resilience measures should be mandatory for detailed project reports. Increasing hydrometeorological networks and interleaving vulnerability mapping into road asset management will help prioritize investment where it matters most.
While these reforms seem costly, prevention is the cheapest insurance. Global evidence shows that every dollar spent on resilience saves at least four are saved in recovery. For Nepal, with annual road repair costs already exceeding Rs 3 billion, the choice is obvious.
The road ahead
While decisive early action can be effective in minimizing risks, it cannot substitute for durable infrastructure. Preparedness can save lives, but only resilience saves livelihoods.
The BP Highway disaster is more than just a damaged road; it serves as a warning. The next storm is imminent. Safeguarding every trip, whether to school, the market, or home, requires investing in resilience now, not in repairs later.
(Rajan KC is a civil/geotechnical engineer working on disaster mitigation and resilient infrastructure.)