From the Return of Water to Composite Risk: Hazards, Damage and Vulnerability in the Southern Korama Valley (Zinder, Niger)
Saley Moussa Hassan *
Laboratoire Géoressources et Géosciences de l'Environnement (LGGE), Doctoral School ED-SSD, André Salifou University of Zinder, Zinder, Niger.
Ibrahim Mamadou
Laboratoire Géoressources et Géosciences de l'Environnement (LGGE), Doctoral School ED-SSD, André Salifou University of Zinder, Zinder, Niger.
Souleymane Issa Malam Salmanou
Faculty of Science and Technology, André Salifou University of Zinder, Zinder, Niger.
Luc Descroix
UMR PALOC (Local Heritage, Environment and Globalisation), IRD / MNHN / CNRS, 43 rue Buffon, 75005 Paris, France.
*Author to whom correspondence should be addressed.
Abstract
Background: The southern Korama Valley of Niger is an endorheic basin where the accumulation and persistence of surface water in interdunal depressions create challenges for rural communities. The interaction of groundwater rise, prolonged flooding and seasonal salt concentration poses potential risks to agricultural production, household infrastructure, vegetation and local livelihoods. Understanding these interconnected hazards is essential for assessing the spatial distribution of damage and socio-economic vulnerability in the affected communes.
Aims: To show that the return of rainfall in the endorheic southern Korama valley produces a composite risk of linked climate, hydrological and hydrochemical hazards acting on vulnerable households.
Study Design: Mixed-methods case study combining climate series, remote sensing, groundwater records, in situ water measurements, a household survey and focus groups.
Place and Duration of Study: Rural communes of Kwaya, Bandé and Dungass, Zinder Region, Niger; fieldwork from September 2024 to April 2026.
Methodology: We analysed rainfall (1950-2024) and temperature (1994-2024) records at Magaria using the Mann-Kendall, Sen and Pettitt tests; Landsat classifications (1975-2025); a Sentinel-1/2 inventory of cuvettes (2020-2025); groundwater records from 23 piezometers (2014-2023); electrical conductivity (EC) and pH measurements at 20 cuvettes in January and April 2026, summarised using a salinisation risk index mapped for each cuvette; a survey of 293 households; and a count of 504 woody plants. A socio-economic vulnerability index (SVI) was computed by commune.
Results: Annual rainfall showed no significant trend (P = .65), but six of the seven seasons from 2018 to 2024 were in surplus and minimum temperature rose by 0.63 °C per decade (P < .001). Water surfaces rose from 847 ha (2000) to 5,223 ha (2025). The water table was less than 2.6 m deep at 8 of 12 piezometers and rose at 4. Mean EC doubled between January and April (from 2.2 to 4.4 dS/m) and exceeded 5 dS/m in seven cuvettes, all in Bandé, while groundwater EC stayed at 0.12 dS/m. Overall, 95% of households reported at least one building collapse, 97% reported crop losses, and 15.5% had sold a field; 45% of woody plants were dead. Dungass had the highest SVI (0.61).
Conclusion: The risk works as a chain from rainfall to land loss. It is mainly perceived in Kwaya, contrasted and dynamic in Bandé and moderate in Dungass, calling for groundwater and water-quality monitoring and household-level measures.
Keywords: Composite risk, endorheic basin, interdunal depressions, groundwater rise, salinisation, flooding, vulnerability