DESIGNING A TERRITORIAL EARLY WARNING SYSTEM FOR RAINFALL-INDUCED LANDSLIDES: THE CASE OF BLANTYRE CITY, MALAWI.

Landslides triggered by heavy rainfall pose a significant threat to Blantyre City. Climate change is expected to further increase frequency and intensity of these events. The overall goal of this study was to design a Territorial Early Warning System that provides sufficient lead time. For this goal, the study involved comprehensive review of relevant literature (including published and unpublished sources) to identify relevant components that constitute the EWS. Additionally, a susceptibility analysis using the Frequency Ratio (FR) Model was conducted with historical landslide data (from 2022 to 20223) and Causative Factors (including 2023 annual rainfall as trigger) to create landslide susceptibility map for Blantyre City. The susceptibility map revealed areas surrounding hills and mountains such as Soche, Chigumula, Bangwe, Bangwe Mthandizi, Mpingwe, Nyambadwe, Michiru and Ndirande to be highly susceptible to rainfall-induced landslides. The proposed EWS consists of a network of sensors; rain gauges for monitoring rainfall, extensometers for measuring slope movement, and piezometers for monitoring pore pressure. These sensors will collect and transmit data (rainfall amounts, pore pressure, and slope movement) to an administrative analysis and forecasting center. The center will analyze the data and trigger phased warnings (gradually escalating warnings based on the severity of the threat) to all key stakeholders through various communication channels, especially media outlets. It has been emphasized that the proposed system should be managed by relevant government institutions in collaboration with other key departments and stakeholders due to the multidisciplinary nature of Rainfall-Induced landslides forecasts.