Detecting and Ranking Urban Flood Risks in Developing Countries: Case of N’Djamena, Chad

Keywords: Developing country, Abidjan, Cote d'Ivoire, Ivory Coast, Ghana, Accra, Spatial Analysis, Urban flooding, Flood, Hazard, Risk, Watershed analysis, Khartoum, Sudan, Ndjamena, Chad, Africa
Abstract Type: Paper Abstract

Abstract

An increasing number of urban communities are taken by surprise with unprecedented flooding episodes resulting in loss of lives and property damage. Most urban areas in developed countries have access to numerous tools to assist victims during and after the events. In contrast, most developing countries face much greater challenges associated with similar events. In the most economically challenged countries, some common issues are inadequacy of the storm drainage systems, lack of warning systems, vulnerability of the citizens, and lack of support programs during and after catastrophic events. In such countries, coping with flood hazards requires approaches that are adapted to the specificities of the local cultural, social, and financial situation. Since these developing countries are often lacking accurate forecast and evacuation systems, it appears that solving the recurring issue of urban flooding must start with the identification of risk areas, and then the evaluation and adoption of approaches to reduce the severity and extent of flood incidents and related damages.
This study presents a low cost and replicable process to systematically identify flood risk zones of any urban area with a precarious storm drainage system. The solution combines spatial analyses tools and data gathered from open source web sites, digitizing and remote sensing techniques. In essence, the study utilizes a watershed and overlay analysis-based model to integrate hydrological and structural features in order to reveal the impediments to storm water paths in selected large cities of developing countries (Abidjan, Côte d'Ivoire, and Accra, Ghana, Khartoum, Sudan and N’Djamena, Chad).