THE Himalaya is the youngest mountain system on the planet and is still rising. Four major tectonic junctures—the Trans Himadri Thrust, the Main Central Thrust (MCT), the Main Boundary Thrust (MBT), and the Main Frontal Thrust—run parallel to the Himalaya from the west to east, dividing the range into four major tectonically active domains from north to south. Besides, a large number of major and minor faults criss-cross the whole mountain range, intensifying the tectonic instability of the region. The Himalayan mountains are rising by more than 1 cm a year as the Indian Plate continues to move northwards.
This movement is continuously pushing the mountains and increasing their seismic vulnerability and height. Given this, many of the Himalayan ranges are located in Zone IV and Zone V of the Seismic Zonation Map and have witnessed several devastating earthquakes in recent years. These tectonic traits render the entire Himalayan region geologically unstable, tectonically alive, and environmentally fragile even without human interference of the scale now seen.
As a result, land mass movement, such as creeping, upliftment, subsidence, faulting, fracturing, slope failures, and landslides, is commonly observed in the region. The construction of hydropower projects, the widening of roads, tunnelling and blasting, and the phenomenal increase in roads and buildings on the fragile slopes severely trigger the inbuilt tectonic instability of the mountain ecosystem.
Rapid urban growth
The Himalaya is considered the most densely populated and most rapidly urbanising mountain ecosystem in the world and Uttarakhand is the most rapidly urbanising Himalayan State, both in terms of urban population and number of towns. According to the 2011 Census, more than 30 per cent of Uttarakhand’s population lives in urban areas as against the 25 per cent average urban population of all Himalayan States. Increasing trends of rural outmigration, improved road connectivity, rural markets, and the phenomenal growth in tourism are the significant drivers of this rapid urbanisation.
In recent years, even comparatively inaccessible areas are urbanising rapidly because of the growth of domestic tourism, marketing, and the clamour for new tourist destinations. This has meant a tremendous increase in the size, area, number, and complexity of urban settlements in Uttarakhand, which has been accompanied by enormous expansion of urban infrastructure both in towns and in their hinterlands.
Besides the fact that climate change and climate change-induced natural disasters are compelling people to migrate from rural areas to urban settlements in all hill regions, people are also moving in search of jobs and better civic amenities.
Uttarakhand’s urban population increased from 16.36 per cent of the total in 1971 to 20.7 per cent in 1981, 22.97 per cent in 1991, 25.59 per cent in 2001, and 30 per cent in 2011. Worse, the absence of an urban land-use policy has pushed urbanisation from the geologically more stable mid-slopes and ridges to the environmentally sensitive higher elevations and right down to the floodplains. Unfortunately, this whole process of urbanisation is unplanned, unregulated, and unsystematic. The absence of any urban development planning policies is glaring. The mountain ranges located between the MCT in the north and the MBT in the south constitute the most densely populated tract of the Himalaya. More than 95 per cent of the fast-growing townships, most of the densely populated rural areas, and most of the agricultural land and infrastructure are located in this belt.
Important towns such as Joshimath, Almora, Nainital, Mussoorie, Rishikesh, Dehradun, Uttarkashi, Tehri, Srinagar, Bageshwar, Munsiari, Gopeshwar, Gangotri, Badrinath, and Kedarnath are located either along the MCT and the MBT or in their proximity. Moreover, large parts of Nainital, Mussoorie, Pauri, Joshimath, and Munsiari have come up on tectonic scarps, landslide scars, landslide fans, debris cones, moraine deposits, and chronic landslide zones. The most densely populated towns are situated in tectonically active domains and are, therefore, susceptible to slope failure and landslides. The natural risks of unplanned urban growth are clearly discernible in urban centres such as Joshimath, Nainital, Mussoorie, and Almora.
Nainital, located close to the MBT, has experienced devastating landslides since its evolution. The cities of Srinagar and Bageshwar lie sprawled out on the floodplains of the mighty Himalayan rivers. Such concentrated urbanisation has been accompanied by intensive and reckless modifications of the fragile slopes and riparian areas, which invariably trigger land mass movement, landslides, and flooding.
Even as the built-up area in these mountainous towns has increased by almost 33 per cent in the past two decades, in the absence of any official policy, more than 60 per cent of this construction has been concentrated in environmentally unsafe zones, particularly landslide and flood-prone areas.
This has increased the vulnerability of most such areas to a variety of geohydrological hazards. Urban encroachment into forests has not been regulated, disruption of natural drainage has not been stopped, cutting and deep excavations on hill slopes to erect buildings and infrastructure have been allowed has catapulted the frequency of landslides to dramatic proportions in Uttarakhand. The encroachment, obstruction, and obliteration of natural drainage channels has increased the vulnerability of the slopes to geohydrological risks, putting most towns under the threat of repeated landslides and mass movements.
In principle, construction activities are not allowed in areas that have more than a 50 per cent slope, but in practice, building codes and by-laws are violated in almost all the Himalayan towns; building safety is not considered an important issue. The percentage of the urban population inhabiting landslide-prone zones, steep slopes, lower river terraces, and slums has increased respectively by 6, 8, 14, and 12 per cent in the State between 2011 and 2021.
The other face of this urban growth is intensive and rapid land use changes, with the consequent disruption of ecosystem services. These changes disrupt hydrological processes in the mountains. Studies have revealed that the amount of surface run-off from urban areas is much higher than that in other land use categories.
The increasing density of the urban built-up areas is thus causing significant damage to underground water resources by reducing groundwater recharge, which in turn means a decline in the water-generating capacity of springs and streams. It also triggers mass movement.
Most towns in Uttarakhand were meant for small permanent populations and a limited and seasonal influx of tourists. The urban amenities were suited for this. But the unplanned mushrooming of houses and hotels and the large number of tourist arrivals have far exceeded the carrying capacity of the towns. This has impacted roads, water supply, sanitation and drainage, garbage disposal, transportation, and more. With such expansion, social, economic, and environmental inequalities increase. The hills today see a large number of slums alongside drainage channels, fragile slopes, and water channels, and other environmentally unsafe developments.
The growth of slums in an area that is already ecologically sensitive has further increased the vulnerability of large populations of the impoverished and marginalised to climate change-induced risks. The proportion of the urban population living in environmentally unsafe areas, below the poverty line, without access to sanitation, without access to drinking water, and without access to roads has increased, respectively, by 20, 25, 10, 7, and 6 per cent in Uttarakhand over the past two decades.
The role of climate change
Climate change is responsible for triggering the severity of geohydrological disasters by increasing the frequency of high-intensity rainfall in Uttarakhand Himalaya over the past 15-20 years. Despite realising the increasing vulnerability of such areas to climate change-related risks, the Uttarakhand government has not evolved any specific climate change adaptation or disaster risk reduction plan for any of its cities. In recent decades, fluctuations in precipitation patterns brought about by climate change have posed a serious threat to the ecologically fragile, tectonically active, and densely populated urban ecosystems of the State.
Despite this, no detailed climate vulnerability risk assessment has been done from the viewpoint of natural disasters, particularly climate change-induced geohydrological risks for these townships. A series of ambitious and large urban development plans, funded by the Central and State governments, are currently being implemented in the Himalayan provinces. Neither the State Climate Change Action Plan for Uttarakhand nor city development plans include any adaptation measures or disaster risk reduction measures.
Prakash C. Tiwari is Senior Fellow, Indian Council of Social Science Research, and Professor Emeritus, Department of Geography, Kumaun University, Nainital.
- The Himalaya is the youngest mountain system in the world and is rising by more than 1 cm a year.
- Many of the Himalayan ranges are located in Zone IV and Zone V of the Seismic Zonation Map and have witnessed several devastating earthquakes in recent years. The entire Himalayan region is geologically unstable, tectonically alive, and environmentally fragile even without human interference.
- The region is prone to land mass movement, such as creeping, upliftment, subsidence, faulting, fracturing, slope failures, and landslides.
- The construction of hydropower projects, roads, and buildings; the widening of roads; and tunnelling and blasting increase the inbuilt tectonic instability of the mountain ecosystem.
- Despite this, the Himalaya is considered the most densely populated and most rapidly urbanising mountain ecosystem in the world and Uttarakhand is the most rapidly urbanising Himalayan State, both in terms of urban population and number of towns.
- Climate change and climate change-induced natural disasters are also compelling people to migrate from rural areas to urban settlements in all hill regions.
- The built-up area in the State’s mountainous towns has increased by almost 33 per cent in the past two decades, and without the benefit of an official urban planning policy.
- A series of ambitious and large urban development plans, funded by the Central and State governments, are currently being implemented in the Himalayan provinces but do not include any climate change adaptation measures or disaster risk reduction measures.