Himalayan Geology, Vol. 38 (2), 2017, pp. 193-205, Printed in India
Landslide inventory and damage assessment in the Bhagirathi Valley, Uttarakhand, during June 2013 flood
RAKESH BHAMBRI1*, MANISH MEHTA2, SHWETA SINGH2, R. JAYANGONDAPERUMAL2, ANIL KUMAR GUPTA2, 3, PRADEEP SRIVASTAVA2
1Centre for Glaciology, Wadia Institute of Himalayan Geology, Dehradun 248001, India
2Wadia Institute of Himalayan Geology, Dehradun 248001, India
3Indian Institute of Technology, Kharagpur 721302, India
*Email(Corresponding author): rakeshbhambri@gmail.com
Abstract: Extreme rainfall event of June 2013 in Uttarakhand Himalaya has been considered as one of the most life-threatening hydro-meteorological hazards of the state during the last decade. To analyse impact of this event on slope movements, we produced a comprehensive landslide inventory and identified new, reactivated, old and inactive landslides in the Bhagirathi valley using pre-event and post-event high resolution Resourcesat 2 Linear Imaging Self-Scanning sensor (LISS) IV satellite images (cell size 5.8 m). Detailed field work was also conducted in the Bhagirathi valley under the multi-institutional initiative to collect ground observations of landscape damage using mobile applications.
A total of 2,772 landslides (15.91 km2) were mapped. Out of these, 1,434 have been classified as new landslides (5.20 km2) and 533 as reactivated (6.16 km2) and 451 as old landslides (3.33 km2). We also identified 354 (1.21 km2) landslides in the pre-event satellite images that are not present in the post-event 2013 LISS IV images. This suggests that older landslides settled with time and were not reactivated in the June 2013 event. About 56% of new landslides occurred on south facing slopes (including southwest and southeast) whereas north (including northwest and northeast), east and west facing slopes account for only 15%, 17% and 11% of total new landslides respectively. The south facing slopes receives more solar radiation than the north slopes that leads to more freeze/thaw cycles or wet/dry cycles on south facing slopes which reduces the strength of the soil and makes the area more susceptible to landslides. We collected field data at 2,339 points on damages that include landslides related damages (756 counts), damaged bridges and culverts (37 counts), eroded land cover and natural resource (92 counts), river bank erosion (160 counts), damaged roads (395 counts), buildings (667 counts) and other infrastructures (232 counts). The database generated in the present research will facilitate to other disciplines (e.g. settlements planning) for long-term reconstruction work in the affected areas of the Bhagirathi valley.
Key words: Himalaya, Bhagirathi valley, extreme rainfall event, landslides, Kedarnath tragedy.
