Fluvial flood risk assessment in rural settlements along the Sirba River in Niger
Description
This dataset contains the key information to estimate the fluvial flood risk in the 4 main settlements along the River Sirba, Niger. The hypothesis is that fluvial flood hazard has increased in recent years and that many exposed assets remain in the riparian communities. The data concern: 1) the maximum annual discharge between 1956 and 2020 as measured at the Garbey Kourou hydrometer 2) the location of Garbey Kourou, Larba Birno, Tallé, and Touré 3) the flood hazard map showing three flood probability scenarios with return periods of 10, 30, and 100 years and the River Niger backwater flood zones with return period of 20 years 4) the detailed list of all assets in the three flood zones (houses, barns, latrines, boreholes, wells) with their geographic coordinates and the fenced fields as surveyed in 2018-19 5) the replacement value of exposed assets by settlement and exposed zone 6) the risk level by settlement and zone. These data confirm that catastrophic fluvial flood hazard has greatly increased in the last decade and that several exposed assets persist, despite repeated flooding. This dataset can be used to monitor the dynamics of fluvial flood risk along the Sirba River and to inspire other assessments in similar contexts.
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Steps to reproduce
Risk (R) is conceived here as the product of Hazard (H) and potential Damages (D): R = H x D. Risk assessment uthe the terminology and the steps defined by ISO 31010 international standard. The data were collected from the daily registrations at the Garbey Kourou hydrograph, from the visual photo interpretation of very high resolution satellite images (Garbey Kourou and Tallé) completed by ground survey, and by Unmanned Aerial Vehicle (Larba Birno and Touré). The flood-prone zones are detrerminated by 1D hydraulic modeling using HEC-RAS 5.0.6. The geometry of the Sirba River was determined by GNSS topographical survey of 147 river cross sections along the 108 terminal km of the Sirba River before its confluence with the Niger River. The survey was realized with RTK and PPP. Images of Larba Birno and Touré were taken by UAV used a Sony ILCE -5100 camera and an experimental sensor to generate RGBN and RGB ortho-photos of 6 cm/px and 4 cm/px respectively. Google earth freely available satellite images were used in Garbey Kourou and Tallé. The replacement values of the exposed assets are derived from discussion with the 4 communities of interest (cost of reconstruction of houses, barns, latrines, disinfection of flooded wells, etc.) and statistics from the Ministry of Agriculture and Livestock and the Departmental Service of Agriculture as observed on the Gotheye market (agricultural yields per hectare and prices).