NEPAL – Hazards in the Himalaya do not queue up politely to occur one at a time. More often, they occur together and, when they do, their cumulative effect is greater than the sum of their parts.
When floods and landslides happen at once, for instance, the impact of each is intensified by the other. Still, it remains common to approach risk reduction for each hazard individually. In Nepal, and the wider Himalayan region, the coincidence of multiple hazards necessitates a multi-hazard approach to disaster risk reduction.
At best, considering one hazard at a time is wishful thinking. At worst, single-hazard approaches reduce the risk of one hazard only to increase the risk from others. To avoid these tradeoffs, a multi-hazard approach manages the connections between hazards to reduce overall risk.
Shifting perspective from single- to multi-hazard risk may appear subtle, but our recent research shows the stakes are high. Our team studied three dominant hazards — floods, landslides, and wildfires — and found that many Himalayan residents live in areas highly susceptible to more than one of them.
If other hazards (like drought, heat stress, or earthquakes) were added to our study, it is likely that the population exposed to multi-hazards would be even higher. The predictions made by hazard models can vary considerably and their results depend especially on which set of previous hazards they consider, but the message emerging from this research is clear:Since many people in the Himalaya live in multi-hazard environments, managing one hazard at a time could have disastrous consequences.
Importantly, adopting a multi-hazard approach does not mean making things more complicated. Instead, it can identify synergies to address them together, while providing a basis for collaboration for aligning single hazard management and governance practices that could otherwise conflict.
A multi-hazard approach is relatively new, but multi-hazards themselves are already here. They can take many forms. Sometimes, one hazard causes another: In 2015, the Mw 7.8 Gorkha earthquake caused thousands of landslides and claimed thousands of lives.
Or, in February of this year, a rockslide triggered massive flooding in the Chamoli district of Uttarakhand, claiming over 70 lives and damaging multiple hydropower projects. Other times, hazards happen together. For example, this year’s monsoon season caused destructive flooding and landslides in many districts in Nepal (the effects of which were exacerbated by the ongoing pandemic).
Other threats loom on the horizon. The latest report by the UN Intergovernmental Panel on Climate Change (IPCC) makes it clear that climate-related multi-hazards will become more common and more intense in the future. Glacial lakes at risk of outburst flooding are growing due to climate change, while changing precipitation patterns could make both seasonal flooding and forest fires more frequent and destructive. These changes interact in complex ways, raising the overall threat from multi-hazards.
As climate change intensifies multi-hazards, current patterns of urbanisation will continue to put more people in harm’s way. Our research shows a high level of settlement in areas also prone to multi-hazards; people may be unaware of multi-hazard risk, or immediate concerns for their livelihood overrule potential future risk from catastrophic multi-hazards.
In either case, people settle in multi-hazard-prone areas to access economic, healthcare, or educational opportunities. Thus, an important component of reducing risk is in providing sustainable livelihoods in less risky areas. Impoverished people in multi-hazard areas may not have the resources necessary to recover from disaster or to settle in safer areas if those areas have lower levels of access.
Gender disparities increase risks to women, and religious minorities may not have equal access to disaster preparedness resources in some places. Multi-hazards are natural events with human effects. Thus, beside technical and governance issues, a multi-hazard approach should consider how multi-hazards multiply the risks faced by already vulnerable populations.
With a multi-hazard approach, synergies are possible. For instance, soil bioengineering is an established set of techniques in Nepal that focuses on conditions — vegetation, drainage, and sediment — that contribute to multiple hazards. By focusing on the conditions where hazards intersect, practices like bioengineering could be more suitable for a multi-hazard environment than those that focus on reducing the risk of a specific hazard alone.
Without a multi-hazard approach, reducing the risk from one hazard could increase the risk of another. In the wake of this year’s fire season, for example, unvegetated buffers around developed areas may seem like a good option for preventing fire damage to structures. But these areas more easily erode, potentially contributing to landslides or mudflows. Similarly, slope stabilisation to prevent landslides, especially around road cuts, can increase surface runoff and exacerbate flooding.
Engineering approaches are important, but multi-hazard risk reduction is not just a technical problem. Governance issues are at the root of both major opportunities and challenges for mitigating multi-hazard risk. A significant obstacle to adopting a multi-hazard approach is existing mandates for governing bodies to manage single hazards in isolation.
For example, federalisation in Nepal gave the Ministry of Home Affairs the mandate to manage forest fire risk, but the mitigation of floods and landslides, which interact with forest fires, often remains at the municipal level. These divisions can lead to conflicts between agencies, while a multi-hazard approach can align mandates otherwise focused on single hazards. Nepal’s Disaster Risk Reduction Strategic Action Plan is already taking steps in this direction.
In addition to managing connections between hazards, governance practices aimed at reducing multi-hazard risk can facilitate two other forms of collaboration: across borders, and between people, residents and otherwise, with different forms of expertise.
First, current collaboration across borders in the Himalaya should be expanded and strengthened. Both hazards and people cross borders, so multi-hazard mitigation must do the same. This last summer, for instance, a landslide-dammed lake in the Rongxer basin in China threatened Nepali settlements downstream along the Tama Kosi River with flooding.
Further along the same river, sedimentation in Nepal is one of many factors contributing to downstream flooding in Bihar, India. The establishment of cross-border early warning agreements is an important way to reduce these risks and is a first step toward connecting upstream and downstream risk reduction through a multi-hazard approach.
Second, the collaboration between people with different types of knowledge about hazard risk — including technical, development, and local experts — is essential for ensuring the success of risk reduction programs. An inspiring precedent for this kind of collaboration is the development of jholmal natural fertiliser and pesticide.
The development of jholmal required combining local practices with the work of technical specialists and efforts to reduce chemical runoff and farming costs to create a cost-effective formula easily communicated to and replicated by the region’s residents and other local experts. This collaborative and multi-pronged approach can serve as model for mitigating multi-hazard risk.
A focus on multi-hazards does not contradict the need to reduce the risk associated with individual hazards; instead, a multi-hazard approach is an opportunity to align risk reduction measures to avoid tradeoffs and find synergies.
Adopting a multi-hazard approach may present technical or governance challenges but the opportunity is clear: in the face of ongoing climate change and urbanisation, effective disaster risk reduction in environments such as Nepal, the Himalaya, and other mountainous regions necessitates a multi-hazard approach.
Jack Rusk is a member of the Urban Himalaya research team. Urban Himalaya is an international, interdisciplinary, collaborative research partnership that seeks to understand urbanization and vulnerability in the Himalaya. Our recent research on multi-hazards was published in the journal Science of the Total Environment.