Geo-hydrological disasters in the Uttarakhand Himalaya: assessment and mapping

The Uttarakhand Himalaya is highly prone to geo-hydrological disasters—landslides, flash floods, cloudbursts, debris flows, rock falls, extreme weather, and land submergence. Cloudbursts and glacier bursts generally trigger these disasters, which are very active and frequent in the Uttarakhand Himalaya and occur mainly during the monsoon season. This study examines the geo-hydrological disasters in the Uttarakhand Himalaya, which occurred from 2020 to 2023 mainly during the three months of Monsoon season. Further, the study assesses the magnitude of the disaster and maps the disaster hotspot areas. Both qualitative and quantitative approaches were used to conduct this study. Data on geo-hydrological hazards that occurred from 2020 to 2023 in Uttarakhand were gathered from multiple sources such as the records of the State Disaster Management Department, Dehradun, various media reports—print and electronic, and personal observation of some affected areas through field visits. Further, an empirical study of the Bandal and Song River valleys was conducted. These valleys were severely hit by a cloudburst-triggered flash flood and debris flow. Household-level survey of the damage caused by huge flash floods and debris flows in three villages of Bandal Valley was carried out. The data were analyzed and mapped and the Uttarakhand Himalaya was divided into disaster hotspots and frequency zones. ArcGIS was used to construct maps and the Google Earth imagery and Sentinel 1-SAR were the major sources of maps. This study recommends that the construction of settlements, infrastructural facilities, and economic avenues should be banned in the most disaster-affected areas, along river valleys, and on fragile slopes. Eco-disaster risk reduction, such as conserving forests and wetlands, and plantation drives in the most degraded areas such as the river banks and fragile slopes, can help communities to prepare for disasters.