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Difficulty: MediumDrainage Patterns and River Basin Analysis

Match each drainage basin morphometric property listed on the left with its corresponding geomorphic or hydrological significance on the right.

  • High Drainage DensityReflects highly impermeable surface rocks, steep relief, and a fine surface drainage texture.
  • High Bifurcation RatioIndicates strong structural geological control (such as folding or faulting) distorting natural stream branching networks.
  • High Form FactorDescribes a circular basin shape leading to concentrated tributary runoff and sharp peak flood discharge.
  • Low Stream FrequencyCorresponds to permeable underlying rock, high infiltration capacity, and a coarse surface drainage texture.

Answer

High Drainage Density matches with highly impermeable surface rocks, steep relief, and fine drainage texture; High Bifurcation Ratio matches with strong structural geological control; High Form Factor matches with a circular basin shape leading to concentrated runoff and sharp peak floods; Low Stream Frequency matches with permeable underlying rock, high infiltration capacity, and coarse drainage texture.
High Drainage Density matches impermeable rocks and steep relief because runoff forms numerous channels. High Bifurcation Ratio indicates structural geological controls such as faulting. High Form Factor denotes a circular basin producing concentrated tributary runoff and sharp flood peaks. Low Stream Frequency corresponds to permeable rock where infiltration reduces stream channel generation.

Step-by-Step Solution

1
Examine the physical controls on Drainage Density (Dd=∑LAD_d = \frac{\sum L}{A}) and Stream Frequency (Fs=NAF_s = \frac{N}{A}).
High drainage density occurs when surface runoff is high and infiltration is low due to impermeable rock and steep slopes. Conversely, low stream frequency indicates high surface permeability where water infiltrates underground rather than forming channels.
Understanding surface runoff dynamics and bedrock permeability.
2
Analyze the geomorphic implication of the Bifurcation Ratio (Rb=NuNu+1R_b = \frac{N_u}{N_{u+1}}).
While values between 3 and 5 are typical in hydrogeologically uniform basins, values significantly higher than 5 reflect tectonic or structural geological distortion such as faulting.
Identifying structural controls in river network organization.
3
Relate Basin Form Factor (Ff=AL2F_f = \frac{A}{L^2}) to basin geometry and flood hydrographs.
Form factors approaching 1 describe circular basins where tributaries feed into the main trunk stream at similar travel times, yielding a sharp, high peak discharge.
Evaluating how basin shape governs runoff timing and flood risk.

Key Concept

Quantitative Morphometric Analysis of River Basins
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Topics

Drainage Patterns and River Basin Analysis

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