The River Niger exhibits a unique hydrological regime featuring a vast inland delta (the Macina) in Mali, where severe transmission losses occur due to high evapotranspiration and seepage in the semi-arid Sahel. Which of the following hydrological factors is primarily responsible for sustaining its downstream volume as it flows through Niger Republic and into Nigeria?
- The seasonal flood surge generated by heavy summer monsoon rains in its humid headwaters in the Fouta Djallon highlands, augmented by the influx of the Bani River.Cevap
- BSubterranean seepage and direct overflow discharging westward from the Lake Chad endorheic basin into the upper Benue River.
- CHigh-altitude snowmelt and torrential upper-course tributaries originating from the Ahaggar and Tibesti mountain massifs.
- DContinuous subterranean inflow from the Nile River catchment moving westward across the Sudanian zone into the Niger basin.
Cevap
The River Niger's flow into its middle and lower courses is sustained by the seasonal flood surge originating from heavy summer monsoon rainfall in the Fouta Djallon highlands of Guinea, combined with significant tributary inflow from the Bani River.
The upper River Niger originates in the high-rainfall Fouta Djallon plateau of Guinea, receiving heavy monsoonal precipitation. This generates a massive seasonal flood wave. As the river enters Mali, the Bani River contributes critical additional volume before the main flow enters the Macina inland delta, allowing sufficient water to survive extreme evaporative losses and sustain the middle and lower river courses.
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Anahtar Kavram
Hydrological regimes and discharge characteristics of major African rivers