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Difficulty: Very hardRelief, Physical Regions, and Drainage Systems of Nigeria

The Biu Plateau in northeastern Nigeria is a distinct physical region formed by Cenozoic volcanic activity, setting it apart from the surrounding Hawal Plains. How does this specific basaltic volcanic geology influence the local drainage pattern and hydrogeological characteristics of the plateau?

  1. The volcanic dome structure gives rise to a radial drainage pattern, while the permeable basaltic cap rocks promote groundwater infiltration and escarpment spring discharge.Answer
  2. B
    The folded metamorphic rock complex produces a trellis drainage pattern, resulting in deep subterranean karst dissolution channels.
  3. C
    The thick alluvial river deposits yield a dendritic drainage pattern characterized by extensive oxbow lakes across the plateau summit.
  4. D
    The horizontal sedimentary sandstone layers generate a parallel drainage network bounded by asymmetric cuesta escarpments.

Answer

The volcanic dome structure gives rise to a radial drainage pattern, while the permeable basaltic cap rocks promote groundwater infiltration and escarpment spring discharge.
The Biu Plateau is a highland volcanic feature in northeastern Nigeria composed of basaltic lava flows. Its elevated dome topography forces streams to flow outwards in all directions, creating a classic radial drainage network. Additionally, the weathered and jointed basaltic rock layer acts as a permeable cap that absorbs precipitation, storing groundwater which discharges as freshwater springs along the plateau's peripheral escarpments into surrounding river basins such as the Hawal River.

Step-by-Step Solution

1
Identify the geological composition and physical structure of the Biu Plateau.
The Biu Plateau consists of young basaltic lava flows forming a high volcanic dome landform over the older Basement Complex.
Geological origin dictates both surface topography and rock porosity/permeability.
2
Determine the resulting surface drainage pattern from a central high volcanic dome.
Streams originate near the central peak and flow outward in all compass directions, producing a radial drainage pattern.
Radial drainage naturally develops on conical or domed relief features like volcanoes and highland plateaus.
3
Analyze the hydrogeological behavior of basaltic lava rocks.
Jointed and porous basalt allows high water percolation, forming aquifers that emerge as natural springs along plateau escarpments.
Basaltic rocks retain fractured structures and vesicles that facilitate groundwater storage and discharge.

Key Concept

Influence of Basaltic Volcanic Relief on Drainage Patterns and Hydrogeology in Nigeria
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Topics

Relief, Physical Regions, and Drainage Systems of Nigeria

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