Ground Based Wireless Instrumentation and Real Time Monitoring of Pakhi Landslide, Garhwal Himalayas, Uttarakhand (India)

Abstract

Despite our increasing knowledge on the subject, the damage tolls due to landslides are on rise during monsoon in Indian Himalayan terrain. Therefore, the installation of a real-time monitoring system is often a cost-effective risk mitigation measure. A Landslide Observatory with wireless instrumentation for real time monitoring of ground deformation and hydrologic parameters has been established at Pakhi Landslide in Garhwal Himalayas, India. The measurement sensors include in-place inclinometers (IPI), piezometers, wire-line extensometers and an automatic weather station (AWS). The real time data is being monitored to establish warning thresholds. The annual cumulative rainfall during 2015 was 1388 mm with cumulative monsoon period (June to September 2015) rainfall of 825 mm. At the crown of landslide beyond main scarp, there is negligible displacement being the stable part. Within the main body of the landslide, it could be inferred that the colluvium, greatly weathered bedrock and their interface experience somehow greater extent of movement at different depths in comparison to the interface between greatly weathered bedrock and unweathered bedrock. A correlation between higher intensity rainfall events and displacement pattern across the inclinometer sensors is also witnessed. However, these inferences can only be established with further data analysis of later periods.