Meander belt width definition: In river engineering, the width of a meander belt is the transverse distance between which two characteristic points of successive bends?
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AApex point of one bend and apex point of the reverse bend
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BApex point and the nearest crossing point
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CThe two banks of the meandering river at one cross-section
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DNone of these
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EMidpoints of alternate crossings
Answer
Correct Answer: Apex point of one bend and apex point of the reverse bend
Explanation
Introduction / Context:Meander geometry is described using wavelength, amplitude, belt width, and radius of curvature. These descriptors help to set river corridor widths and plan levee alignments.
Given Data / Assumptions:
- Planform of a free meandering river.
- “Apex” refers to the outermost point of a bend.
Concept / Approach:The meander belt width quantifies the lateral sweep of the river pathway. It is commonly taken as the transverse distance between the apices of two successive bends in opposite directions (a bend and its reverse bend).
Step-by-Step Solution:Identify two consecutive alternate bends (left and right).Locate their outward apices (maximum lateral excursions).Measure the transverse separation between these apices → meander belt width.
Verification / Alternative check:Textbook sketches show belt width as twice the meander amplitude for symmetrical planforms; apex-to-apex distance aligns with this definition.
Why Other Options Are Wrong:
- Apex-to-crossing: Measures along-meander shift, not belt width.
- Two banks at one section: That is just the river width, not belt width.
- Midpoints of crossings: Not a standard definition.
Common Pitfalls:Confusing bankfull channel width with meander belt; measuring along the thalweg instead of transverse to valley axis.
Final Answer:Apex point of one bend and apex point of the reverse bend