Rational method in stormwater design: The widely used rational formula for estimating peak drainage discharge (Q = C * i * A) was evolved by which engineer?

Introduction / Context:
The rational method is one of the oldest and most widely applied tools in urban drainage design for estimating peak runoff from small catchments. The question checks historical attribution, reinforcing foundational knowledge used in sewer and stormwater sizing.

Given Data / Assumptions:

• Peak discharge is estimated using Q = C * i * A (consistent units).
• Method is typically applied to small, relatively uniform urban catchments.
• Historical inquiry: who formally evolved and popularized the formula in modern practice?

Concept / Approach:
While early ideas about runoff predate the 19th century, Emil Kuichling (late 1800s) is credited with evolving and systematizing the rational formula for American practice, including guidance on selection of runoff coefficients and critical storm duration (time of concentration). Recognizing the name helps link design practice to its origins and literature.

Step-by-Step Solution:
Identify the formula: Q = C * i * A.Recall the historical figure associated with formalizing the method: Emil Kuichling (1889 era).Select the corresponding option.

Verification / Alternative check:
Standard hydrology texts cite Kuichling for the rational method’s evolution and adoption in urban drainage design, noting assumptions such as uniform rainfall intensity over the duration equal to time of concentration.

Why Other Options Are Wrong:
Lloyd-Davies: Associated with runoff coefficients and UK practice, but not the original evolution of the rational formula.Fruhling: Not credited with evolving the method.Mulvaney: An early contributor in runoff estimation history, but the rational method in current form is attributed to Kuichling.“All of these”: Historically inaccurate.

Common Pitfalls:

• Confusing early contributors with the engineer who evolved the method in modern design context.
• Assuming “All of these” when multiple familiar names appear.

Final Answer:
Kuichling