Flood risk assessment along the River Niger
Description
The dataset used to build a novel Flood Risk Assessment (FRA) for semi-arid rural areas is provided here. Our FRA aims to address the recurring shortcomings in multi-hazard, participation, and risk reduction in the FRA for semi-arid rural regions published over the last decade. We hypothesise that assessing flood risk by integrating high-resolution geoinformation and local knowledge in a participatory process enables the identification of risk reduction measures, thereby contributing to flood risk assessment in risk management. Data show the flood-prone area of the River Niger upstream of the city of Niamey during local and Guinean floods, each with three probabilities of occurrence (return periods of 10, 30, and 100 years). Moreover, the data include the basin of the Karma Wadi (the largest tributary of the Niger River, which is reported to flood crops along the River Niger) and the highlands requiring treatment. Further information in the dataset includes assets exposed to each flood, expected damage, risk levels for each of the five municipalities along the river, potential risk-reduction measures, and their cost-benefit analyses. The main findings of the FRA are: 1) River flooding during the dry season causes more damage than during the wet season 2) Expected damage to irrigated crops is greater than damage to buildings 3) High-resolution geoinformation and local knowledge identify a feasible risk reduction 4) Raising the levees of rice fields, hygiene, and sanitation are priorities 5) High land prices hinder resettlement and redirect land development The data consists of an Excel file reporting (i) crops, settlements, buildings (footprint and number) exposed to 6 flood scenarios organised by municipality; (ii) expected damage, (iii) SWOT analysis on measures; (iv) Measures priority; (v) Risk reduction; (vi) Cost-benefit analysis. Moreover, five folders contain shape files of flood-prone areas, categorised by six scenarios (two types of floods and three probabilities of occurrence each), water depth, and assets (crops and buildings). Finally, two figures in PNG format localise each flood-prone settlement mentioned in the tables. Data were gathered from daily river discharge data provided by the Ministry of Hydraulics and Sanitation of Niger, a digital elevation model extracted from Planet satellite images and land cover Google Earth images of February 2024, the Information System on Rural Markets (SIMA), field inspections on February 2025, and focus groups conducted with the municipalities of Gothèye, Karma, Kourteye, and Namaro in 2024 and 2025. The dataset can be used for flood rescue and recovery, an impact-based flood early warning system, local risk reduction planning, and local emergency planning.
Files
Steps to reproduce
The flood-prone area due to river flooding was determined using daily river discharge data (1971-2024) from the Kakassi (River Dargol), Garbey Kourou (River Sirba), and Niamey (River Niger) stations, a digital elevation model with 4 m horizontal and 3 m vertical resolution, specifically created from 50 PlanetScope images captured in 2019-2021, and the BASEMENT 2D hydraulic model. The flood-prone area due to tributaries' flooding (Karma Wadi) was determined using daily precipitation data (1994-2025) from the Karma station. Floodplain accuracy was assessed by overlaying the predicted inundated area with the observed inundated area captured by Sentinel-2 on August 20, 2024 and February 16, 2025, processed using the Modified Normalised Difference Water Index. Assets were identified from visual interpretation of Google Earth Pro images in February 2024 and field inspections in February 2025. The asset value was obtained from crop prices reported in the Niger Information System on Rural Markets (SIMA) in August 2024 and February 2025, and from compensation for buildings recognised in recent public works in Niger. Risk was a function of hazard and expected monetary damages. Risk reduction measures were identified with a participatory SWOT analysis and prioritised in focus groups with the municipalities of Gothèye, Karma, Kourteye, and Namaro. The benefit-to-cost ratio for risk treatment was determined through a cost-benefit analysis. A 10-years horizon (limited to 4 years for half-moon measures) was adopted. Each measure was considered to be implementable within one year. The net present value was therefore calculated using the 5.5% legal discount rate established by the Central Bank of West African States for Niger.
Institutions
- Politecnico di Torino
Categories
Funders
- Italian Agency for Development CooperationGrant ID: AID 012487