APIPA Flood Alert System for the Antananarivo Plain

When the Sisaony passed 4.15 m against its 3.5 m red mark in February 2025, boats were evacuating Ampitatafika the same day. Antananarivo's flood authority turns river gauges into alerts — people do the rest.

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The Autorité pour la Protection contre les Inondations de la Plaine d'Antananarivo (APIPA) defends the low-lying capital with dikes, storm basins and six pumping stations led by Ambodimita — and runs the flood announcement system that turns river gauges into formal alerts. During storms it issues dated bulletins reading levels of the Ikopa, Sisaony and Mamba against fixed thresholds — on the Sisaony at Ampitatafika, yellow at 3.0 m and red at 3.5 m; on the Ikopa at Ambohimanambola, yellow at 3.5 m. When the Sisaony passed 4.15 m at Ampitatafika on 15 February 2025, civil-protection and BNGRC crews evacuated residents by boat the same day, and bulletins were still driving commune-level alerts in February 2026. It is a warning-and-crews system, not an automated one: pumps, road closures and evacuations all run on people acting on the readings, and whether the gauges transmit automatically or are read by observers is not documented in the sources APIPA makes accessible.