Abstract
<jats:p>Before Cyclone Senyar made landfall on Sumatra in November 2025 it drew moisture from across the South China Sea, Gulf of Thailand and Indian Ocean. The substantial damage its heavy rainfall caused on the NE and W coasts of Sumatra urges us to rethink the relationships between climate, forests, hydrology, land use, human presence, and vulnerability; the simple ‘deforestation causes floods’ narrative is no longer adequate to guide a building-back-better strategy for the areas affected. We reviewed key concepts and framing of the links between ocean temperature, atmospheric moisture transport (‘rivers in the sky’), rainfall extremes, saturation of the existing buffers, river flow and flooding as they account for the space-time pattern of Senyar effects with its multiple landfalls. Atmospheric roughness (slowing down sky rivers and unloading precipitation), surface infiltration and water retention in the soil profile, and mid- and downstream flow delays due to water retention depend on land cover beyond what a simple forest—nonforest terminology can represent. Rather than indiscriminate tree planting efforts, future adaptation and disaster avoidance efforts should balance the reduction of human exposure through effective land use planning and efforts to reduce hazard by restoring and managing vegetation cover and drainage systems.</jats:p>