Flood hazard in Malawi

Abstract

This article presents the methodology and key findings of the first national study of flood hazard conducted across Malawi as part of the 2016–2021 GEMMAP programme. After outlining Malawi's geomorphological, climatic, and hydrographic features, we detail the approach used for flood hazard assessment and mapping. Ten flood types were identified, reflecting diverse morphological, geological, and climatic settings, resulting in flood hazard maps, which cover the entire country and highlight areas at risk based on flood type and magnitude. The total area exposed to flooding in Malawi is estimated at 16% of the country's surface area (around 15 000 km2). Flooding of plains along major rivers, such as the Shire River, which affects hundreds of thousands of people, accounts for approximately 37% (5100 km²) of Malawi's flood-prone areas. Flooding in dambo areas comprise 34% (4700 km²), and lake shores another 10% (1400 km²). Although debris flow flooding is restricted to around 4.2%, it nevertheless frequently causes significant casualties and damage. The remaining surface area corresponds to the narrow flood zones on either side of the secondary rivers. Specific flood contexts are analysed in detail, including the Shire River-Lake Malawi flood connection, debris flows in mountainous regions, and river mobility in lowland areas. The methodology has been designed to be simple and pragmatic, enabling easy adaptation and application in countries with similar geographical contexts and limited flood hazard knowledge.