Community-based rainfall observation for landslide monitoring in western Nepal

This paper discusses community-based approach applied for observing rainfall to monitor landslide probability in Bhanu village development committee (VDC), Tanahun District, Nepal. Vulnerable communities were supported with geological study to make them understand the causes of landslides. Participatory assessment was conducted to acquire information and perceptions regarding their risks, vulnerabilities, and capacity. Participatory assessment revealed that communities perceive rainfall as a major triggering factor for landslide. Literature were reviewed to reckon rainfall-based landslide probability. Historical landslide events were correlatedwith rainfall data to scrutinize the relationship between rainfall and landslides. Two types of rainfall measuring systems, automatic and manual, were installed in the community for rainfall observation. Both short duration-high intensity and long durationlowintensity rainfall can trigger landslide probability. Therefore, communities are monitoring rainfall for two periods: 1-h rainfall and 24-h rainfall. Based on the literature review, past landslides events and rainfall data, communities made agreement for disseminating alert message when rainfall amount surpasses either 50 mm in 1 h or 200 mm in 24 h. The rainfall data of two monsoons (2012 and 2013) showed that the rainfall amount never reached to the identified limits. Nonetheless, communities were alert and in frequent communications with rainfall monitor during the monsoon. This case study of Bhanu VDC concludes that localized rainfall observation by communities is not only important for exploring rainfallbased empirical thresholds for landslide probability but also to assess, analyse, and act to reduce the risk associated with landslide. This approach reckons the benefit that communities are empowered and self-reliant to take their own decisions. Support on scientific knowledge, however, could be the limitation after the withdrawal of external facilitation