Assessment of landslide hazards induced by extreme rainfall event in Jammu and Kashmir Himalaya, northwest India

• Published in: Geomorphology (Amsterdam, Netherlands) Vol. 284; pp. 72 - 87
• Main Authors: Kumar, Amit, Asthana, AKL, Priyanka, Rao Singh, Jayangondaperumal, R., Gupta, Anil K, Bhakuni, SS
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2017
• Subjects: Extreme rainfall; Indian Summer Monsoon; Landslide hazards; Orography; Orography; Landslide hazards; Extreme rainfall; Indian Summer Monsoon
• ISSN: 0169-555X; 1872-695X
• DOI: 10.1016/j.geomorph.2017.01.003

In the Indian Himalayan region (IHR), landslide-driven hazards have intensified over the past several decades primarily caused by the occurrence of heavy and extreme rainfall. However, little attention has been given to determining the cause of events triggered during pre- and post-Indian Summer Monsoon (ISM) seasons. In the present research, detailed geological, meteorological, and remote sensing investigations have been carried out on an extreme rainfall landslide event that occurred in Sadal village, Udhampur district, Jammu and Kashmir Himalaya, during September 2014. Toward the receding phase of the ISM (i.e., in the month of September 2014), an unusual rainfall event of ~488.2mm rainfall in 24h took place in Jammu and Kashmir Himalaya in contrast to the normal rainfall occurrence. Geological investigations suggest that a planar weakness in the affected region is caused by bedding planes that consist of an alternate sequence of hard, compact sandstone and weak claystone. During this extreme rainfall event, the Sadal village was completely buried under the rock slides, as failure occurred along the planar weakness that dips toward the valley slope. Rainfall data analysis from the Tropical Rainfall Measuring Mission (TRMM) for the preceding years homogeneous time series (July–September) indicates that the years 2005, 2009, 2011, 2012, and 2014 (i.e., closely spaced and clustering heavy rainfall events) received heavy rainfalls during the withdrawal of the ISM; whereas the heaviest rainfall was received in the years 2003 and 2013 at the onset of the ISM in the study region. This suggests that no characteristic cyclicity exists for extreme rainfall events. However, we observe that either toward the onset of the ISM or its retreat, the extreme rainfall facilitates landslides, rockfall, and slope failures in northwestern Himalaya. The spatiotemporal distribution of landslides caused by extreme rainfall events suggests its confinement toward the windward side of the Himalayan front. •Extreme rainfall events cause maximum number of landslides and flash floods in the Himalaya during peak monsoon season.•Orographic effect in rainfall distribution is the major contributing factor leading to landslide and flash floods.•Establishment of relationships between rainfall intensity threshold and landslides over the Indian Himalaya is possible.•No characteristic cyclicity exists in extreme events in the Indian Himalayan region.•In Himalaya, dense network of hydrometrological stations should be deployed.