Contrasting hydrological controls and multisectoral vulnerability in the Kafue and Jonkershoek catchments of Southern Africa

Southern African water insecurity is often described at regional scale, yet management decisions are made within catchments whose dominant controls, observation systems and vulnerable sectors differ substantially. This review aims to develop a comparative hydrological control-regime framework using two deliberately contrasting cases: the large, tropical and strongly regulated Kafue River system in Zambia, and the small, Mediterranean-climate Jonkershoek experimental catchments in South Africa. A structured critical evidence synthesis was undertaken using verified peer-reviewed studies and authoritative institutional sources, with evidence coded according to external forcing, catchment modifier, hydrological mediator, sectoral receptor, management response, and uncertainty. The comparison shows that Kafue vulnerability is primarily infrastructure-mediated: reservoir operations and multi-sector demand reshape the flood pulse, redistribute water through time, and create trade-offs among hydropower, irrigation, floodplain livelihoods and biodiversity. Jonkershoek vulnerability is primarily vegetation-mediated: plantation forestry, wildfire and recovery alter evapotranspiration, quick flow, baseflow and downstream water yield. Published observations indicate that channel overflow supplies about 45% of seasonal water inputs to the Kafue Flats, while baseflow contributes 38–86% of annual streamflow across three Jonkershoek headwaters. These quantities are not directly comparable; their value lies in identifying different transmission mechanisms. The novel contribution is therefore mechanism-based rather than metric-based: catchment vulnerability emerges from the interaction between climatic forcing, a dominant human or landscape modifier, the hydrological process through which change is transmitted, and the sectors exposed. The framework identifies distinct management leverage points: coordinated operating rules and environmental-flow protection in Kafue, and plantation, invasive-plant and fire-recovery management in Jonkershoek. It also provides a reproducible basis for future scenario modelling and decision support. Contrasts infrastructure-mediated and vegetation-mediated water vulnerability. Introduces a control-regime framework linking drivers, flows and sectoral receptors. Shows why absolute water-stress metrics cannot be transferred uncritically across scales. Identifies environmental flows and vegetation management as distinct leverage points. Defines a reproducible agenda for comparative monitoring and predictive modelling.