ASSESSMENT OF THE LANDSLIDE SUSCIPTIBILITY AT MIDIMA HILL IN MIKOLOGWE AREA, CHIRADZULU, SOUTHERN REGION.

The devastating landslides triggered by Cyclone Freddy in March 13–15, 2023 on Midima Hill in Mikolongwe, Chiradzulu District, caused significant damage to crops, farmland, livestock, and infrastructure, highlighting the significant need for landslide risk assessment in the region. Despite the evident threats, no any studies have been conducted to examine landslide triggers or mapped susceptibility zones in this area. This research aimed to fill that gap by assessing key factors influencing landslide occurrence such as lithology, slope gradient, slope aspects, elevation, and land use to create a detailed landslide susceptibility map. This study used GIS to map landslide risks in Midima Hill. Data on slope steepness, lithology, elevation, slope direction, and land use were collected from geological survey of Malawi, satellite images, soil databases, and field surveys. These factors were analyzed in ArcGIS, where each was ranked based on its influence on landslides using a method called AHP (Analytic Hierarchy Process). Finally, a landslide risk map was created by combining all factors, showing areas from very low to very high risk. Findings revealed that weak, foliated rocks like gneiss and fractured rock like migmatite were highly prone to failure, especially on steep slopes at angles greater than 22°, east- and southeast-facing slopes, which receive heavy rainfall. And it also High elevation zones (>900m) accounted for 70% of landslides due to gravitational forces and slope instability. Land use also played a significant influence on landslide occurrence: bare ground and farmland on slopes were vulnerable because they support erosion and weathering processes, while vegetation provided stability through their roots that anchor the soil and rocks to avoid erosion. The final susceptibility map classified 20.3% of the area as high risk and 13.6% as very high risk, with field validation confirming the model’s accuracy through GPS-mapped landslide scars and inventory data. Recommendations to mitigate the risks include avoiding construction in high-risk zones, implementing agroforestry in farms to stabilize slopes, enhancing drainage systems in weak rock areas, and adopting terraced farming to mitigate erosion. These measures aim to reduce future landslide impacts, safeguarding communities and infrastructure.

The devastating landslides triggered by Cyclone Freddy in March 13–15, 2023 on Midima Hill in Mikolongwe, Chiradzulu District, caused significant damage to crops, farmland, livestock, and infrastructure, highlighting the significant need for landslide risk assessment in the region. This research aimed to fill that gap by assessing key factors influencing landslide occurrence such as lithology, slope gradient, slope aspects, elevation, and land use to create a detailed landslide susceptibility map. Findings revealed that weak, foliated rocks like gneiss and fractured rock like migmatite were highly prone to failure, especially on steep slopes at angles greater than 22°, east- and southeast-facing slopes, which receive heavy rainfall. Land use also played a significant influence on landslide occurrence: bare ground and farmland on slopes were vulnerable because they support erosion and weathering processes, while vegetation provided stability through their roots that anchor the soil and rocks to avoid erosion.

The study was carried out at Midima hill in Mikolongwe veterinary college, T/A Nkalo Chiradzulu district, southern region of Malawi. The area is part of Phalombe-Thuchira plain which is found to the East side of the district. The area is extended between latitudes -15521.2 and longitudes 351324.27 and is approximately 500meters from MUST turnoff. Geologically, chiradzuru District is underlain by the Basement Complex rocks of the Mozambique Belt, which are composed of gneisses, migmatites, granites, and greenstones (Evans, 1965). The Basement Complex rocks are overlain by younger sedimentary rocks, mainly sandstones, shales, and conglomerates of the Karoo Supergroup, which were deposited during the Permian and Triassic periods (Evans, 1965). Understanding the geology of an area is very important, as it can provide information on the types of rocks and their properties, which influence landslides occurrence (Gariano & Guzzetti, 2016). The area experiences a warm tropical climate with mean temperatures ranging from 16C to 28C and in exceptional temperatures rise as high as 32C (State climate of Malawi, 2023). The lowest temperatures experienced in June and July while the highest temperatures are registered between the months of October and November (State climate of Malawi, 2023).

Traditional authority: TA Likoswe

District: Chiradzulu

Coordinates: -15.8038, 35.1596