Instrumentation and monitoring of Mahawewa landslide off Walapane

Abstract

The instability of the slope area at Mahawewa, Walapane has been identified as a major threat to the people and properties of the vicinity since 1986. Therefore, National Building Research Organization has started a project of monitoring and stabilization of the slope, cooperating with the Japan International Cooperation Agency in 2010. Main involvement of this study was to do the monitoring part. It is mainly based on analysis of un-stabilization parameters of the area which measured using five instruments. That is horizontal movement at sub surface using Inclinometer, fluctuation of ground water level using Piezometers, characteristics of slip surfaces using Strain Gauges, movement of the surface using Extensometers and rainfall using Rain Gauges. In addition drill log data of the site, visual information of cracks generated and springs available were also used. Global Positioning System survey was carried out for preparation of a map in this particular area. Finally, according to the results and conclusions gained from monitoring of the landslide, a suitable mitigation method was proposed.