Affiliations: [a] W.R.S. Division, National Institute of Hydrology, Roorkee, Uttarakhand, India | [b] School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India
Abstract: On 12 June 2018, the Tirisha village in Nubra valley, Ladakh experienced a flash flood from a cloudburst that occurred over the mountain ridge. This event was captured in a Sentinel 2B satellite image at the time of its occurrence. The image also provided unique visual evidence of the constrained area of a cloudburst for the first time. Field survey of impact area at the Tirisha village was carried out on 13 June 2018. It was followed by assessment of the impact at the place of occurrence and further downstream using satellite data taken on, before and subsequent days. Satellite data show small area where cloudburst impact (< 1km2) from a cumulonimbus (Cb) cell of ~2.97 km2 of cloud top area. Rest of the flood catchment remained cloud-free during the event and floodwater in the stream is clearly visible in the imagery. The flash flood entered the Tirisha village situated at the Nubra valley foothills, which destroyed a stretch of 100 m road. Previous studies have suggested inherent atmospheric instability over the arid Ladakh region with an extremely high-temperature lapse rate of >9.8 K/km during 40-70 days during summer months. The extremely constrained nature of this event highlights the challenges involved in monitoring, forecasting and managing such events in the Himalayan region.
