INVESTIGATING THE DRIVERS OF THUCHILA RIVER COURSE ALTERATION IN GROUP VILLAGE HEAD NOGWE, TRADITIONAL AUTHORITY NKANDA, MULANJE DISTRICT, MALAWI

This research investigates the physical and spatial impacts of the Thuchila River’s course alteration on flood patterns and extent in Group Village Head (GVH) Nogwe, Mulanje District, Malawi. While local flooding is often broadly attributed to extreme weather such as the legacy of Cyclone Freddy and a 129 mm daily rainfall peak in 2025 this study addresses a critical gap in documenting the underlying geomorphological and spatial drivers. Using a quantitative geospatial and hydrodynamic approach, the research integrated Two-Dimensional (2D) HEC-RAS modelling, Remote Sensing, and GIS analysis (p. 20). Longitudinal Land Use and Land Cover (LULC) analysis between 2013 and 2025 revealed a dramatic landscape transformation: settlement areas expanded from 7% (26.1 ) to 54% (198.7 ), largely through the conversion of 174.6 of bare land (pp. 31, 33, 36). This aggressive anthropogenic encroachment degraded natural riparian buffers, fundamentally amplifying the region's hazard profile. Hydrological estimations using the Rational Method derived a peak discharge of 191.74 for the 2025 extreme rainfall event was calculated. The 2D hydraulic simulations physically validated the river's avulsion mechanics, mapping new inundation zones with water depths reaching a maximum of 6.39 meters. These modelled outputs, corroborated by field transect walks, demonstrate that the redirected floodwaters now inundate previously safe zones, threatening agricultural livelihoods and causing family displacement. The study concludes that evidence-based land-use planning and community-led resilience strategies are essential to mitigate the heightened flood risks engineered by catchment degradation and climatic variability.

This research investigates the physical and spatial impacts of the Thuchila River’s course alteration on flood patterns and extent in Group Village Head (GVH) Nogwe, Mulanje District, Malawi. While local flooding is often broadly attributed to extreme weather such as the legacy of Cyclone Freddy and a 129 mm daily rainfall peak in 2025 this study addresses a critical gap in documenting the underlying geomorphological and spatial drivers. Longitudinal Land Use and Land Cover (LULC) analysis between 2013 and 2025 revealed a dramatic landscape transformation: settlement areas expanded from 7% (26.1 ) to 54% (198.7 ), largely through the conversion of 174.6 of bare land (pp. The study concludes that evidence-based land-use planning and community-led resilience strategies are essential to mitigate the heightened flood risks engineered by catchment degradation and climatic variability.

The study is localized in Group Village Head (GVH) Nogwe, within Traditional
Authority (T/A) Nkanda in Malawi’s Mulanje District, focusing specifically on the 366.9
square-kilometer Thuchila River catchment. Topographically, the river descends from
the steep, high-altitude terrain of the Mulanje Massif into the flat, low-lying floodplain
of GVH Nogwe. This abrupt transition from high to low gradients rapidly decreases
flow velocity, driving heavy sediment deposition. Consequently, the natural
geomorphology makes the local riverbanks highly susceptible to lateral erosion,
meandering, and the avulsion events central to this research.
Climatically, the region experiences a tropical savanna climate driven by the Inter
Tropical Convergence Zone and cyclonic systems. These torrential rains generate
massive runoff from the massif, periodically overwhelming channel capacities.
Compounding this physical vulnerability is the area's socio-economic reliance on rural
agriculture. Over the 12-year study period (2013-2025), aggressive anthropogenic
encroachment systematically converted bare land into settlements and agricultural
plots. This rapid expansion severely degraded the protective riparian buffer,
fundamentally amplifying the spatial hazard profile of the GVH Nogwe community

Traditional authority: TA Nkanda

District: Mulanje

Coordinates: -15.8476, 35.4729