Climate Change, Extreme Rainfall and Increasing Landslide Hazard in the Himalayas
DOI:
https://doi.org/10.31305/rrijm.2026.v11.n07.026Keywords:
climate change, extreme rainfall, landslide hazard, cloudburst, rainfall threshold, Uttarakhand, HimalayaAbstract
This paper assesses the impact of changing rainfall characteristics and extreme precipitation on changing landslide hazards in the Uttarakhand Himalaya using secondary, quantitative synthesis of recent, validated studies. Long term analysis of rainfall in Nainital (2000–2021) shows increasing rainfall, though this trend is not statistically significant, with a Sen's slope of +4.558 mm yr⁻¹, and a significant increase in the number of wet days. The event in October 2021 recorded about 270 mm of rainfall on 18-19 October and caused widespread flooding and landslides. In 2020-2021, across Uttarakhand, thirty significant cloudburst events were recorded, seventeen of them in 2021. Independent field evidence along the NH-7 corridor of Rishikesh–Joshimath following the extreme 2022 rainfall documented 309 landslides along the 247 km road section, or at a rate of 1.25 km landslides/km. Of these, about 80% occurred after January 2022 and approximately 30% of this group were reactivated landslides. A Bayesian point process model yielded an AUC of 0.79 (95% bootstrap CI of 0.76 – 0.82) and identified rainfall, slope, lithology and road widening as credible controls. The research from Garhwal even further supports this, stating that about 0.45 – 0.50 mm/hr sustained over a period of 48 hours and about 80 mm of rainfall over a period of 15 days can lead to shallow failures. The available data shows increasing hydro-meteorological stress, but a simple attribution of landslides to climate is not justified. Landslide hazard is caused by extreme rainfall, fragile geology, wet antecedent conditions, slope, and construction.
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