Subtopic: Power efficiencies and measurement, engine performance curves
Question Statement:
The incorrect statement from the following is
Options:
(A) The peak runoff from an agricultural watershed is generally less than that from an urban watershed of the same area
(B) The horizontal hydraulic conductivity of soil is less than its vertical hydraulic conductivity
(C) The magnitude of a 75-year flood is less than that of a 100-year flood
(D) The rating curve due to an unsteady flood event forms a loop
Official Answer Key:
B
Step-by-Step Solution & Explanation
(A) is a true statement — impervious urban surfaces produce faster, higher peak runoff than vegetated agricultural land for the same rainfall and area. (C) is true — a larger return period (100-year) corresponds to a rarer, larger-magnitude flood than a 75-year flood. (D) is true — unsteady (looped) rating curves are a well-known hydraulic phenomenon during flood rise/recession (higher stage for the same discharge on the rising limb). Statement (B), however, is incorrect: due to the layered, anisotropic nature of natural soils (stratification), the horizontal hydraulic conductivity is typically greater than, not less than, the vertical hydraulic conductivity. Hence (B) is the incorrect statement, and is the correct choice for this question.
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