This article is not intended to demonise landslides, but to understand their complex role in shaping the Himalayan landscape and its communities, particularly their habitation pattern.
Landslides, while destructive, have paradoxically been instrumental in facilitating human habitation in these challenging terrains.
Water: The Lifeline of Mountain Communities
Water scarcity is a perennial issue in the Himalayas, despite abundant rainfall and glacier-fed rivers. Steep slopes lead to rapid runoff, while groundwater distribution is uneven, and glacial meltwater is often unsuitable for consumption.
Landslides play a crucial role in water conservation. The porous landslide debris acts as a sponge, retaining rainwater and gradually releasing it. Erosion, redistribution and deposition of finer sediments often creates impervious layers within the landslide debris, forms perched water bodies that serve as vital sources for mountain communities.
Soil: The Foundation of Agriculture
Agriculture, essential for sustenance, depends on availability of fertile soil. Landslides, through physical and biological weathering processes, accelerate soil formation. This explains why most agricultural terraces in the Himalayas are built upon old stabilized landslide deposits.
The Traditional Wisdom of Himalayan Communities
Mountain communities traditionally understood the inherent instability of landslide-prone areas as also old landslide material over which they developed agricultural fields. While they utilized the water and fertile soil, they wisely chose higher, firmer ground for their dwellings. This minimized their exposure to floods, landslides, and even earthquakes, as firmer ground experiences less seismic amplification.
They at the same time didn’t build bunds on far flung and hard to manage agricultural terraces as stagnation of water could induce instability. The slope of these fields was designed to promote quick disposal of rainwater.
Furthermore, traditional practices like seasonal migration to higher elevations during monsoons helped mitigate landslide risks. The absence of permanent structures over landslide debris and a conscious limit on population density based on available resources also contributed to their resilience.
Modern Challenges and the Joshimath Crisis
The recent Joshimath crisis serves as a stark reminder of the consequences of disregarding traditional wisdom. Overcrowding, disregard for carrying capacity, and inadequate drainage measures led to excessive water infiltration and accelerated subsidence due to the piping of fines.
The construction of heavy structures on unconsolidated landslide deposits with no consideration of the bearing capacity only exacerbated the problem.
Lessons Learned and the Way Forward
Joshimath is a wake-up call. Unchecked development, overpopulation, and disregard for geological realities can have catastrophic consequences. To avoid similar crises, we must:
1. Respect Carrying Capacity
Limit population density and construction in landslide-prone areas based on the land’s sustainable capacity.
2. Prioritise Drainage
Implement robust drainage systems to minimise piping of fines and reduce the risk of subsidence.
3. Build Responsibly
Construct lighter, more resilient structures suitable for the geological conditions.
4. Embrace Traditional Wisdom
Learn from the sustainable practices of mountain communities who have coexisted with landslides for centuries.
5. Invest in Early Warning Systems
Develop and deploy advanced monitoring and early warning systems to detect signs of instability and evacuate communities in time.
Conclusion
Landslides are an undeniable force of nature in the Himalayas. Yet, their relationship with human habitation is a complex one, marked by both opportunities and challenges. By acknowledging the delicate balance between human needs and geological realities, we can strive for a more sustainable and resilient future in these awe-inspiring mountains.
Excellently explained. Keep it up.