Cheap technology could predict Nepal’s flood risks

Nepal, a country dominated by the mighty Himalayas and its many rivers, is no stranger to natural disasters. The monsoon heralds the end of often arduous dry seasons and brings life-giving rains to a country reliant on agriculture. But it also brings dangerous floods, particularly for those living downstream in the country’s densely populated river valleys and plains. 

Bhopal Pandeya, an ESPA funded research fellow, explains how cheap hydrological sensors could provide communities with an early warning system for floods.

In August 2014 a devastating flood hit half a million residents of the Karnali River valley in western Nepal.  More rain fell in 24 hours than had ever been recorded. In the end the flood claimed 222 lives and affected over 100,000 who had to abandon their homes, or who suffered through damage to businesses and crucial infrastructure1. Unfortunately for Nepal this was far from an isolated incident.

Much of Nepal’s population is concentrated in just three major river valleys and the plains of the Terai region. Towns and villages have grown quickly on these fertile valleys and plains tempting many away from the challenges of agricultural life high in the mountains. Regular flooding during the monsoon is not unusual in these valleys, but increasingly the floods are becoming more severe and unpredictable.

Floods strike in as little as 30 minutes, sometimes in the middle of the night, and are the largest single cause of economic damage and loss of human life in Nepal3. Changing patterns of rainfall, melting glaciers, climate change and changes to land use upstream are all implicated as potential causes, but despite the increasing hazards little has been done to help vulnerable communities adapt. 

Lack of data

In this complex mountainous region understanding when and how changes in the river upstream cause floods in the downstream plains is crucial. The vast Karnali River valley has only one hydrological monitoring station at Chisapani. Although it feeds valuable data to an early warning system for communities living immediately downstream4, it cannot predict all potential flooding risks across the plains. Relying on a single monitoring station is also risky approach if the station stops working in the middle of the monsoon season. Extra monitoring sensors which can reliably transmit real-time data to flood early warning systems are sorely needed.

"Since the Karnali River frequently changes its course during the monsoon, which is further exacerbated by unsustainable development practices along the river channels mainly sand and gravel excavation in the dry season of every year, community-based water level monitoring activities would make local communities more aware of the unpredictable flood water level and may improve our capability to adapt with the future flood risk" - Local participant at a community workshop.

To tackle the issue ESPA-funded research is pioneering a new approach - providing innovative and affordable technology as well as developing local partnerships to protect vulnerable communities. Key institutions including Practical Action Nepal and the government’s Department of Hydrology and Meteorology are partnering with community groups to test new hydrological sensors which monitor changes in the Karnali river level. The approach, also referred to as Citizen Science, has the potential to be used across many of Nepal’s data-scarce remote regions.

Affordable Technology

Each device costs only $250-$300, a fraction of the $12,000 price tag of the existing Chisapani monitoring station. As well as being cheap, they are easy to use and install - which is useful in remote areas. Once the monitoring data is linked to community early warning systems, there is a good chance of improving local resilience and decision making about flood risks. If the river rises to dangerous levels a series of mobile phone alerts can be activated which warn authorities and communities to take action before the flood strikes.

"Additional hydrological monitoring stations enabled by citizen science based low-cost sensors could significantly improve flood resilience capabilities of local communities" - Gehendra Gurung, Head of Programme, Disaster Risk Reduction & Climate Change, Practical Action Nepal

Final testing of the newly installed sensors is underway in the Karnali River valley. If all goes well they will be ready for the start of the monsoon in June, a real test of their ability to provide an early warning system to communities across the valley. Those involved in the trial recognize that new technology alone won’t be enough.  Further research will be needed to check that the sensors offer a reliable alternative to existing decision making on flood risks.

Success will also depend on close collaboration between local partners, authorities and communities as well as providing training on using the sensors and interpreting the data. But if these hurdles can be overcome the technology and partnerships created could offer a major step forward in predicting and adapting to floods in the Karnali River valley and other vulnerable regions across Nepal.