Decision Analysis for Flood Risk Management in Riverine Communities of Delta State

Communities in the Niger Delta region of Nigeria face recurrent flooding that disrupts livelihoods, damages infrastructure, and displaces thousands of residents annually. This study employs decision analysis techniques, including decision trees and expected value criteria, to evaluate alternative flood risk management strategies for selected riverine communities in Delta State, South South Nigeria. Three strategic alternatives are assessed: the construction of earthen embankments, the deployment of early warning systems, and a managed relocation programme. Using hydrometeorological data from the Nigerian Meteorological Agency and community vulnerability surveys administered to 200 households across five communities, probability estimates for flood occurrence under three severity levels are derived. Expected monetary values (EMV) are computed for each alternative under both risk-neutral and risk-averse decision criteria. Results indicate that the early warning system offers the highest EMV under baseline flood probability assumptions, while embankment construction becomes optimal under scenarios of intensifying flood frequency. Sensitivity analysis demonstrates that the optimal choice is highly responsive to changes in the probability of severe flooding events. The study incorporates the minimax regret criterion as an additional decision rule, yielding consistent results. Findings are presented as actionable guidance for Delta State Emergency Management Agency policymakers. This research contributes a structured, quantitative framework for disaster risk management decision-making in Nigeria's most flood-vulnerable geopolitical zone. Keywords: decision analysis, flood risk management, Delta State, decision trees, expected monetary value