Runoff and Hydrographs MCQ with answer and solution

Concept

The SCS-CN method relates precipitation to direct runoff using empirical equations dependent on the hydrologic soil group and land cover.

Formula

Q = (P - I_a)² / (P - I_a + S)

Step-by-step solution

1. Identify the purpose of the SCS method, which is to compute the rainfall-runoff relationship. 2. Recall that it uses cumulative rainfall (P) and curve numbers to estimate direct surface runoff (Q). 3. Match with the correct option.

Explanation

The Soil Conservation Service (SCS) curve number method is a conceptual model used in hydrology to estimate direct runoff volume from rainfall excess based on soil type, land use, and antecedent moisture condition.

Why the other options are wrong

A: Peak discharge is estimated by methods like the Rational Formula or unit hydrograph peak. C: Baseflow recession is modeled using depletion curves. D: Flood frequency analysis uses statistical methods on historical flood data.

Shortcut

Remember SCS = Soil Conservation Service Curve Number method for Rainfall-Runoff estimation.

Common mistake

Confusing it with peak discharge estimation methods like the Rational formula.