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Difficulty: HardRelief, Physical Regions, and Drainage Systems of Nigeria

The Sokoto Plains in northwestern Nigeria constitute a major physical region underlain predominantly by young sedimentary rocks. Which of the following best characterizes the drainage regime and valley landforms of the Rima River system traversing this region compared to rivers flowing across the adjacent crystalline Basement Complex?

  1. A
    The river system cuts deep, narrow V-shaped gorges through resistant metamorphic structures.
  2. The river system features broad, shallow floodplains with pronounced seasonal flow variations over gentle sedimentary terrain.Answer
  3. C
    The river system forms a radial drainage network that discharges northeastward into an inland basin.
  4. D
    The river system maintains a high-velocity perennial flow sustained by steep contour gradients and highland springs.

Answer

The river system features broad, shallow floodplains with pronounced seasonal flow variations over gentle sedimentary terrain.
The Sokoto Plains are underlain by relatively soft, flat-lying sedimentary rocks. Rivers traversing this region, notably the Rima River and its tributaries, carve broad and shallow valleys with extensive seasonally inundated floodplains (fadamas). Because of the seasonal rainfall regime of northwestern Nigeria and the low slope gradient, discharge fluctuates sharply between the wet and dry seasons.

Step-by-Step Solution

1
Analyze the rock structure of the Sokoto Plains region.
The Sokoto Plains are underlain by soft sedimentary rocks of the Sokoto Basin, contrasting with the crystalline Basement Complex of the High Plains of Hausaland.
Geological substrate determines valley shape and resistance to river erosion.
2
Evaluate the relief and slope profile of the region.
The region features low relief and gentle gradients sloping south-west toward the Niger valley.
Topography dictates flow velocity and valley width.
3
Determine the drainage pattern and river regime of the Rima River system.
Low gradient over soft strata produces broad, flat floodplains (locally called fadamas) with significant seasonal discharge fluctuations tied to savanna rainfall cycles.
Combines physical region characteristics with river hydrology to identify the correct drainage behavior.

Key Concept

Relief and Drainage Characteristics of the Sokoto Plains sedimentary basin
Estimated Time:2m 0s
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Topics

Relief, Physical Regions, and Drainage Systems of Nigeria

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