Characterization and Mapping of Flood and Marine Submersion Risk in the Cap-Haïtien Urban Area (PROReV), Final Report

The CIAT commissioned this study because Cap-Haïtien, Haiti's second city, had no map of its exposure to flooding although it floods often and has spread since the 1980s into floodplain, lagoon and mangrove areas. The work, done with the CNIGS, follows a hydrogeomorphological approach in two parts: a historical, rainfall, land-use and field analysis of the causes of flooding, delivered in November 2014, and a hazard mapping with no-build zones and recommendations. The body of the report runs to 70 pages and the annexes to 61.

The rainfall records show that the November 2012 floods followed truly exceptional rain, while the November 2014 floods followed a cumulative rainfall close to the annual average. Field surveys found that in many cases the hazard is created by people: building on hillsides and in ravine beds, filling ravines and rivers with waste and rubble, extending the city onto the estuary banks and mangroves, and drainage works that are undersized, badly designed or unmaintained.

The study produces a hydrogeomorphological map from 1978 aerial photographs, a comparison of land use in 1978 and 2013 showing the city's spread into the bed of the Haut-du-Cap river and around the lagoon, a flood and runoff danger map, and a map of three types of no-build zone, usable at 1:25,000 to 1:10,000. The provisional LIDAR terrain model covered only part of the city. Recommendations cover hazard knowledge, governance and regulation, clearing the Haut-du-Cap river, estuary and ravines, removing settlements from banks and shores, reducing building vulnerability, the design of public works and the MTPTC's capacity, and land-use planning that takes hazards into account. Marine submersion is estimated only briefly, because a UNDP and UNESCO program was to model it in 2015.