Participatory approach for flood risk assessment: the case of Yeumbeul Nord (YN), Dakar, Senegal

Abstract

Flooding has emerged lately as a major threat for poor people in the suburban area of Dakar (Senegal), a densely populated area. In this region, flood events are mainly controlled by rainfall intensity and groundwater level fluctuations.To assess flood risk at a neighbourhood level, accurate data on flood extent, exposure and vulnerability is required. The objective of the present study is to obtain these data combining remote sensing data and local knowledge. Field work data were collected through interviews with inhabitants. About 500 respondents were surveyed with the support of a local association and very detailed mapping was carried out to clearly identify elements at risk. Information collected at the household level concerns: 1) socio-economic data, 2) information on the property, 3) flooded houses and 4) strategies of risk reduction.This research demonstrates that local knowledge is an important tool to obtain accurate data useful for understanding flood hazard and vulnerability patterns. It provides quantitative data at the household level that can be used to complement conventional GIS and remote sensing data.

Reconstituting past flood events: the contribution of citizen science

“…It is one of the most populated districts of Senegal, with 168 379 inhabitants (ANDS, 2015) and a population density of approximately 18 700 inhabitants km −2 . YN is characterised by lowlands with elevation less than 20 m above sea level and is highly urbanised with more than 80 % of its territory covered with buildings, critical facilities and roads (Sy et al, 2016). It is one of the suburbs most affected by flooding.…”

“…Information on the magnitude and intensity of flood events, as well as on processes controlling the flood, is at the core of flood hazard assessment and zoning (EXCIMAP, 2007). This fundamental information is scarcely available in the region (GFDRR, 2014;Sy et al, 2016). The absence of an organised data acquisition system during floods has led to the absence of a comprehen-sive catalogue on past flood events and consequently on flood hazard maps.…”

Flood hazard assessment and the role of citizen science

“…These recommendations highlighted the use of survey protocols and training for volunteers, statistical approaches to collect and treat the data as well as defining a clear structure for the project. When applied to flood hazard, some researchers (Sy et al, ) made provision training prior to data acquisition to ensure that the requested information on flood extent and water level would be surveyed as accurately as possible.…”

“…Several research projects have already involved citizens in that direction. P-mapping and P-GIS have been used in order to map potential or flooded areas (De Andrade & Sy et al (2016) : could be applied for flood analyses; -: not mentioned. Szlafsztein, 2015;Padawangi et al, 2016;Peters Guarin, 2008).…”

“…Various tools are used to involve citizens, which can be classified into two main categories, direct and online. The first category implies observation or mapping activities through active survey (Sy et al, ), participatory mapping (P‐mapping) or participatory Geographic Information System (P‐GIS) (Chingombe, Pedzisai, Manatsa, Mukwada, & Taru, ; De Andrade & Szlafsztein, ; Kienberger, ). The second category involves citizen's participation via the use of Web platforms (Dorn, Vetter, & Höfle, ; See et al, ) or social networks.…”