Hyper-resolution hydrological modelling to assess water and food security in Malawi

Agriculture is a key sector in fighting hunger in Sub Saharan Africa. Almost 95% of the agriculture in Africa is rain-fed and smallholder farmers play a crucial role as they produce most of the food consumed by local populations. These characteristics make the SSA agricultural landscape very diverse and particularly vulnerable to weather extremes. The ability of forecasting hydrological variability has increased in recent years due to advancements in the understanding of hydro-climatic processes, growing availability of high-resolution remote sensing datasets, and the increase of computational power, which has promoted the development of high-quality computer-based hydrological models. When adopted in data scarce regions, these models provide new insight into the hydrological budget and in characterizing the hydrological variability of these areas. In this work, we combine the hyper-resolution hydrological model HydroBlocks and the river routing model RAPID to simulate the spatial and temporal heterogeneity of the land surface processes in Malawi at 30 m resolution. The model simulations show high variability of the hydrological variables, particularly soil moisture, across the country. We use these results to further analyse water and food security indicators in the transboundary catchment of Lake Chilwa shared between Malawi and Mozambique. The start and duration of the maize cropping season and the lake level show a large interannual variability which allow us to quantify the weather-related vulnerability of the local smallholder farming system. This work is part of the research activities of the UKRI-GCRF funded project “Building research capacity for sustainable water and food security in drylands of sub-Saharan Africa” (BRECcIA - http://www.gcrf-breccia.com/).