The contribution of fine-grained exposure to flood risk assessment along the Niger River

Description

The dataset contains information used for flood risk assessment (FRA) along 58 km of the Niger River upstream of the city of Niamey. We hypothesised that a more detailed definition of assets exposed to flooding than that provided by standard flood risk assessments (FRA) developed in low- and medium-income economies would facilitate risk management. The dataset comprises five shapefiles, two data tables, and two tables of information related to the reference FRAs in low- and middle-income economies, published between 2016 and 2025. The shape files contain: (i) Crops, (ii) Buildings, (iii) Guinean floodplain with 2, 5, 10, 30, 100 years of return period, and (iv) Local floodplain with 2, 5, 10, 30, 100 years of return period. The data tables concern: (i) Sixty-three flood-prone settlements according to the return period and floodable buildings, and (ii) flood risk in monetary terms (EUR) according to the probability of occurrence. The information tables concern: (i) forty river FRAs in low- to middle-income economies, 2016-2025, and (ii) risk mapping implications based on forty river FRAs in low- to middle-income economies, 2016-2025.

Steps to reproduce

The shape files were obtained through hydraulic modelling of the Niger River and its right-bank tributaries, Dargol and Sirba, using BASEMENT (ETH Zurich). The historical series of daily flows recorded at the stations of Kakassi (Dargol), Garbey Kourou (Sirba) and Niamey (Niger) were used. We used the SRTM DEM. The floodplain was validated by comparing it with Sentinel-2 images, from which the floodplain was derived using the MNDWI. Assets exposed to local and Guinean floods with return periods of 2, 5, 10, 30, and 100 years were identified through visual photo interpretation of very high-resolution satellite images from February 2024 and 2014, available on Google Earth. Land cover was verified through field inspections of 24 samples, which enabled the determination of land use (type of building, construction materials used, and kind of crop at the time of the Guinean and local floods), as well as the water depth-damage function. The value of the crops is taken from the SIMA-Information System on Agricultural Markets, Ministry of Commece and Industry of Niger. The value of the buildings is based on the average of recent compensation recognised for public works.

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