Developing a Flash Flood Early Warning Protocol for Downstream Communities Along the Kaduna River

Flash flooding along the Kaduna River represents a recurrent humanitarian and economic threat to communities in Kaduna State, demanding professionally structured early warning protocols that connect meteorological monitoring to community response. This study develops and evaluates a flash flood early warning protocol for downstream communities in Chikun, Igabi, and Birnin Gwari LGAs. The protocol integrates upstream catchment rainfall threshold analysis using intensity-duration-frequency curves derived from NiMet records, hydrological routing models calibrated for the Kaduna River basin, and community vulnerability mapping. Stakeholder consultations involving 60 community flood wardens, Kaduna State SEMA officials, and NiMet Kaduna staff informed the design of the alert dissemination chain. The resulting protocol specifies three alert levels: Watch (24-hour rainfall forecast exceeding 50 millimetres), Warning (observed upstream gauge level above 4.5 metres), and Emergency (inundation imminent within two hours). Simulation of the protocol against historical flood events from 2019 to 2023 shows that it would have successfully triggered timely Warning alerts for all four major flood events, with lead times of two to six hours. Community feedback reveals that SMS alerts are preferred by 78 percent of respondents over sirens or radio announcements. Recommendations include formalization of the protocol within Kaduna State's Disaster Risk Reduction Strategy. Keywords: flash flood, early warning, Kaduna River, protocol, community response.