Dhurva Prasad Koirala, who lives in Belaka Municipality's Bhagalpur village near the spot where the river Kosi burst its banks, was expecting a knock on his door in the early hours of the morning, instructing him to evacuate his home.

"We were aware that flood was coming. So due to that, we got a chance to prepare ourselves," said the 33-year-old, who volunteers with the local disaster committee.

"The municipality themselves were alerting the people on social media. Even the army went into the community and spread the message that the flood is coming."

How does it work?

For days before the disaster, the army and local police force were on high alert, watching the embankment for signs of danger after high water flow was detected by river-level sensors and hydro-meteorological stations upstream.

Real-time data was published on a government online portal and disseminated to the local community via radio, SMS messages and social media.

"Around 20,000 people were evacuated during that time. It was only possible because they had lots of time before the flood came to that place — otherwise they would have lost human lives," said Deepak Chapagain, president of the NGO Volunteer Corps Nepal which assisted with the flood response.

The manner in which the community responded demonstrates how early warning systems can help reduce or eliminate death tolls from such severe weather events.

Why is Nepal at risk?

Nepal's topography and network of river systems make it highly susceptible to disasters, a situation that is likely to be exacerbated by climate change.

The number of disasters per year is projected to increase globally from 2015 by 40% by 2030, according to a UN Office for Disaster Risk Reduction (UNDRR) report published earlier this year.

Poorly planned development projects in the fragile Himalayan region are also putting the country at increasing risk, according to Dharam Uprety from NGO Practical Action Nepal.

"Our infrastructure is not designed in a way that considers the impact of the increasing climate crisis, the impact of climate change," he said.

Strengthening early-warning systems

Nepal's Department of Hydrology and Meteorology has been working with NGOs to develop disaster management systems — including river-level monitoring equipment, a community-based system where volunteers upstream alert those downstream about dangerous water levels, and a comprehensive network of hydro-meteorological stations.

The data is collated on the official government online portal, and automatic alerts are sent out via SMS and radio broadcasts to affected areas.

Whilst data collection is important, ensuring that the information reaches the people who need it — and understand how to respond appropriately — is also an essential component of an effective early warning system, according to Marco Toscano-Rivalta, who heads the regional UNDRR office for Asia and the Pacific.

"It's not only about monitoring the hazard, but also reaching the communities that actually need to act on those on those warnings," Toscano-Rivalta explained, emphasising the importance of building early warnings systems with consideration to local knowledge and specific cultural and socio-economic contexts.

"They need to be to be built with and for the people that use them."

In particular, he said, including women — who are often disproportionately affected by sudden-onset disasters — in decision-making processes and volunteer committees is vital for an inclusive disaster response.

Is there room for improvement?

Nepal's community-based Disaster Committee volunteers, like Koirala, are an integral component of its early warning systems, helping to disseminate warnings to those who may not have access to a mobile phone or social media, or are confined to their homes.

Toscano-Rivalta pointed out that while Nepal has made huge strides in strengthening its early warning coverage to reduce death tolls, there are still improvements needed in remote mountain regions.

"There is still a challenge in terms of having warnings that capture the floods in smaller rivers, or flash floods," he said.

Uprety said that in addition to flash floods, there is no early warning system for landslides, which in fragile mountainous regions often occur amid sudden heavy downpours during the monsoon season.

"If we see the casualties in the last 10 years there is a decreasing trend, but an increasing trend of casualties through landslide," he pointed out.

Early warning systems can save lives and prepare residents for disasters — but they cannot fully mitigate the long-term damage caused to property and livelihoods.

"When the flood came we couldn't remove all of our household things. We were just thinking about how to be safe," said Koirala, whose farmland was also inundated, destroying rice crops which would usually feed his family of five for a year.

Still, he is grateful that the early warning system in place allowed him to evacuate in time with his wife and two small children. "We didn't imagine the disaster would be so big," he said.

"If they hadn't given us any warning, the situation could have been much worse."

Edited by: Keith Walker