Infiltration MCQ with answer and solution

Concept

Understanding the fundamental components of the hydrological cycle, including infiltration modeling, loss indices, and evaporation measurement.

Formula

Horton's Equation: f = f_c + (f_o - f_c)e^-kt; Lake Evaporation = Cp × Pan Evaporation

Step-by-step solution

1. Evaluate Statement 1: Horton's equation (f = f_c + (f_o - f_c)e^-kt) specifically models how infiltration capacity decreases over time. (True) 2. Evaluate Statement 2: The Phi-index is defined as the constant rate of rainfall above which the rainfall volume equals the runoff volume; thus, it represents the average infiltration loss. (True) 3. Evaluate Statement 3: In arid regions, the potential evapotranspiration (PET) often exceeds the annual precipitation (P), leading to a water deficit. (True) 4. Evaluate Statement 4: Pan coefficients are empirical values that correct for the pan's metal boundaries, heat transfer through sides, and wind exposure compared to a large water body. (True) 5. Since all statements are correct, the answer is (D).

Explanation

Horton's equation is a standard empirical model for infiltration capacity over time. The Phi-index represents the average infiltration rate during a storm, effectively being the rainfall lost to the ground. Evapotranspiration can exceed precipitation in arid regions or during dry seasons where soil moisture or groundwater is available. The pan coefficient (Cp) is used to adjust observed pan evaporation to actual lake evaporation, accounting for differences in heat storage and wind effects.

Why the other options are wrong

A: Missing statement 3, which is a valid hydrological phenomenon in arid zones. B: Missing statement 1, which is the most fundamental infiltration equation. C: Missing statements 3 and 4, both of which are standard hydrological facts.