At the end of June 2018, I participated in a field visit 40–70 km east of Kathmandu, to the tributaries of the Sunkoshi River. One purpose of this visit was to collect data for a flash flood guidance system, which, among other things, meant measuring river cross sections and interviewing local people at the site about historical flooding events. Another purpose was to support capacity building and become familiar with the challenges faced in mountain areas.

Flash flood refers to flooding that occurs quickly when high intensity rainfall events make a river swell rapidly. This usually occurs in smaller rivers and catchments higher up in the bigger river basins. However, flash floods are not the only hazard that these mountain areas are subjected to. During the three-day trip, we heard stories about and saw the traces and remains of several historical natural disasters. We travelled through areas that had suffered from earthquakes, floods, glacial lake outburst floods, (GLOFs) and landslides. At some locations, it was possible to see traces left behind by events that happened a long time ago. There were big boulders on a field which might have been transported by a historical GLOF or landslide, and after which the river had changed course. In other locations, the traces was more apparent—destroyed houses and buildings were still visible. We saw one house that looked as if it was hanging over the riverbank after strong currents had eaten up the ground underneath. In another area, we saw a couple of houses on another riverbank that have been destroyed by floods and were partly buried in sediments transported by a GLOF.

These old and new traces of big natural disasters made it very apparent to me that the Hindu Kush Himalaya is, geological speaking, a young area, still undergoing very active geological processes. This was not news to me as I knew this from studying geology, but to see the effects with my own eyes was astonishing. What follows with a geologically young and active region is a truly multi-hazardous environment. Landslides, earthquakes, and floods are a natural part of the region, and have shaped it over thousands of years.

It is easy to see the need for knowledge and different aids to cope with the hazards and to mitigate the risks. The houses we saw that had been destroyed by floods were built close to the riverbank. But we also saw undamaged houses built close to rivers in other locations. These houses are subject to the same hazard and made us wonder why houses continue to be built at locations very vulnerable to disasters. The reason may be lack of knowledge, cheaper land prices near rivers, or perhaps something else.

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1. Houses built close to the river destroyed by floods and partly buried in sediment masses. 2. A tributary upstream of Sunkoshi, close to Barhabise, one of the survey sites on the field visit. 3. At Jhiku Khola, we met Prem Lama who shared his experiences of past floods.

What became apparent to me during the trip was the amazing force of these natural disasters, and how miniscule humans appear when these forces are in action. At several locations, barriers had been built to serve as protection from the flooding rivers. However, in order for structural measures to cope with the worst events, they must have great size, which, in most cases, makes them unfeasible to implement. Because of this, it is again important to have informed strategies to adequately prepare for disaster, and react and respond when a disaster hits. Functional warning systems are also important to mitigate the impact of disasters.

For these warning systems to function as intended, there is a need for rainfall and river discharge measurement data that can be used together with rainfall forecasts to assess upcoming flood risks. Stations to collect these data in remote areas present another great challenge in the region.

As I sit in my office writing this in the middle of August, I receive news that there has been heavy rainfall in Barhabise, which has caused flooding and triggered a landslide. A concrete bridge was destroyed but thankfully there were no reports of casualties. I remember walking over that bridge and greeting some playing children, and I find myself thinking about how much the people in these mountain villages and towns must experience during their lifetime.

When I now think about Barhabise, I not only think about the marks that disasters leave in nature and in people’s lives, but also about how life continues after a disaster. In some respects, nothing will have changed, yet nothing will ever be the same again. People will carry on with their daily lives, but the memories will remain.

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