Abstract
In this study, geographic information system (GIS)-based hydrologic and hydraulic modeling was used to perform a flood risk assessment for Onaville, which is a fairly new, rapidly growing informal settlement that is exposed to dangerous flash-flood events. Since records of historic floods did not exist for the study area, design storms with a variety of significant average return intervals (ARIs) were derived from intensity-duration-frequency (IDF) curves and transformed into design floods via rainfall-runoff modeling in hydrologic engineering center’s hydrologic modeling system (HEC-HMS). The hydraulic modeling software hydrologic engineering center’s river analysis system (HEC-RAS) was used to perform one-dimensional, unsteady-flow simulations of the design floods in the Ravine Lan Couline, which is the major drainage channel of the area. Topographic data comprised a 12 m spatial resolution TanDEM-X digital elevation model (DEM) and a 30 cm spatial resolution DEM created with mapping drones. The flow simulations revealed that large areas of the settlement are currently exposed to flood hazard. The results of the hydrologic and hydraulic modeling were incorporated into a flood hazard map which formed the basis for flood risk management. We present a grassroots approach for preventive flood risk management on a community level, which comprises the elaboration of a neighborhood contingency plan and a flood risk awareness campaign together with representatives of the local community of Onaville.
Highlights
According to the World Disaster Report [1], seismic events killed the greatest number of people of all natural hazards in recent years, averaging 50,184 people per year from 2000 to 2008, whereas flood events affected the largest number of people, averaging 99 million people per year between 2000 and2008
Due to the limited data availability, hydrological (HEC-HMS) and hydraulic (HEC-RAS) modeling was applied in combination with a detailed analysis of the local hydro-geomorphology for the flood risk assessment (Figure 8)
This is in accordance with the fact that no significant discharges have been seen in the ravine since the beginning of urban development in the area in 2010 (Interviews with local residents by members of Technical University of Munich (TUM)-USO)
Summary
According to the World Disaster Report [1], seismic events killed the greatest number of people of all natural hazards in recent years, averaging 50,184 people per year from 2000 to 2008, whereas flood events affected the largest number of people, averaging 99 million people per year between 2000 and2008. In January 2010, a 7.0 magnitude earthquake struck Port-au-Prince, the capital of Haiti. It caused more than 300,000 deaths and left more than 1.5 million people homeless [2]. Due to the lack of disaster preparedness, the 2010 earthquake led to an extensive resettlement process in which an estimated 500,000 people spontaneously left the capital and sought refuge in other provinces [4]. This process led to the formation of numerous informal settlements in previously uninhabited areas
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