Flood Routing MCQ with answer and solution

Concept

Hydraulic Routing

Formula

Yes, hydraulic routing is governed by the 1D Saint-Venant equations: Continuity Equation: ∂A/∂t + ∂Q/∂x = q Momentum Equation: ∂Q/∂t + ∂(Q²/A)/∂x + gA(∂y/∂x - S₀ + S\_f) = 0 where A is cross-sectional area, Q is discharge, y is flow depth, S₀ is bed slope, S_f is friction slope, q is lateral inflow, g is gravitational acceleration, t is time, and x is distance.

Step-by-step solution

1. Identify that flood routing based on both the continuity equation and conservation of momentum (Saint-Venant equations) is defined as hydraulic routing. 2. Match this definition directly with Option B.

Explanation

Hydraulic routing method uses both the continuity equation (conservation of mass) and the momentum equation (Newton's second law) to track how a flood wave moves along a river channel. Because it considers physical forces like gravity, friction, and pressure along with flow volume, it accurately predicts changes in water flow, depth, and speed over time and distance.

Shortcut

Remember "Hydraulic = Hydrodynamics" (uses both Continuity/Mass and Momentum/Forces), whereas "Hydrologic = Storage only" (uses only Continuity).

Common mistake

A common mistake is confusing hydraulic routing with hydrologic routing. Many students forget that hydrologic routing relies only on the continuity equation, whereas hydraulic routing uses both the continuity and momentum equations. Additionally, some students select "Flood routing method" simply because it repeats the term used in the question.