A Social-Hydrological Framework for Assessing Irrigation Demand in Malawi: Linking Rainfall Variability and Poverty Dynamics

Abstract

Malawi is an agrarian country highly dependent on rain-fed agriculture located in the Sub-Saharan Africa region which is characterized by a highly variable climate. This study presents a novel quantitative framework for assessing irrigation demand in Malawi by integrating climatic variability with socio-economic vulnerability over the period 2002 to Recognizing that irrigation needs stem not only from rainfall deficits but also from their socio-economic impacts we analyze annual segments capturing environmental and social conditions. Using normalized rainfall and poverty data we establish baselines representing optimal hydrological conditions and minimal social stress (using poverty as a proxy). We define hydrological stress as deviations from maximum rainfall and social stress as deviations from minimum poverty. These deviation metrics are combined into an irrigation need index which captures the compounded impact of water scarcity and poverty. The core of the methodology is an irrigation need index that integrates these stresses amplifying demand during years marked by significant rainfall shortfalls and elevated poverty. To capture temporal dynamics more effectively we interpolate the discrete index into a continuous function enabling the calculation of cumulative irrigation burden and average annual demand. The framework also identifies periods where irrigation need exceeds a critical threshold highlighting years of intensified stress. Key findings reveal an increase in irrigation need between 2020 and 2022 aligning with observed climate and poverty trends. This socially grounded data-driven approach provides a dynamic and policy-relevant tool for diagnosing irrigation urgency supporting more targeted equitable and timely water resource management strategies in Malawi.