This hydrologic and hydraulic engineering study was commissioned by a United Nations agency to develop sustainable water management solutions for flood-prone agricultural areas in a Caribbean island nation. The project tackled flood risk management across four distinct agricultural watersheds, each presenting unique hydraulic challenges and infrastructure constraints that impact agricultural productivity during heavy rainfall events.
The work began with statistical hydrology analysis and derivation of the island’s Intensity-Duration-Frequency (IDF) curves, alongside assessment of climate change impacts on hydrologic parameters using CMIP6 ensemble models. Two-dimensional hydraulic modelling using HEC-RAS software formed the core of the technical analysis. This revealed that flooding in these agricultural watersheds stems primarily from infrastructure bottlenecks rather than natural processes. Road crossings, bridge structures, and uncontrolled embankments create hydraulic restrictions that trigger backwater flooding during rainfall events. Each watershed showed distinct characteristics, from well-developed drainage networks to steep elevation-based land use transitions in smaller systems, requiring tailored engineering approaches for effective flood management.
The recommended flood mitigation strategies blend Natural Flood Management principles with targeted infrastructure interventions. The design centres on vegetated swales with engineered stone check dams for controlled conveyance and sediment capture, working alongside lined retention ponds that serve dual purposes: flood attenuation and agricultural water storage. All proposed interventions account for saline groundwater contamination risks common in small island developing states (SIDS), prioritising above-ground water storage solutions with appropriate lining systems. This prevents infiltration whilst maintaining operational flexibility for both flood control and irrigation.
The study showcases practical hydraulic engineering through numerical modelling, field assessment, and solution development that tackles both immediate flood risks and long-term agricultural water security in challenging Caribbean conditions.
