1. What is Philip's Equation?

Philip's Equation is a widely used formula in soil physics and hydrology that describes the cumulative infiltration capacity of water into soil over time. It accounts for both the sorptive and conductive properties of the soil.

2. How Does the Calculator Work?

The calculator uses Philip's Equation:

Where:

• \( F_p \) — Cumulative Infiltration Capacity (Centimeter per Hour)
• \( s \) — Sorptivity (-)
• \( t \) — Time (Hour)
• \( k \) — Hydraulic Conductivity (Centimeter per Hour)

Explanation: The equation accounts for both the initial rapid infiltration due to capillary action (sorptivity term) and the steady-state infiltration due to gravity (hydraulic conductivity term).

3. Importance of Cumulative Infiltration Capacity Calculation

Details: Accurate calculation of cumulative infiltration capacity is crucial for understanding water movement in soils, designing irrigation systems, predicting runoff, and managing water resources in agricultural and environmental applications.

4. Using the Calculator

Tips: Enter sorptivity, time in hours, and hydraulic conductivity in centimeter per hour. All values must be valid (non-negative, with time > 0).

5. Frequently Asked Questions (FAQ)

Q1: What is sorptivity in soil physics?
A: Sorptivity is a measure of the capacity of a porous medium to absorb or desorb liquid by capillary action. It depends on soil properties and initial moisture content.

Q2: How does hydraulic conductivity affect infiltration?
A: Hydraulic conductivity determines the rate at which water can move through soil under saturated conditions. Higher conductivity values result in greater steady-state infiltration rates.

Q3: What are typical values for sorptivity and hydraulic conductivity?
A: These values vary significantly by soil type. Sandy soils typically have higher hydraulic conductivity but lower sorptivity, while clay soils have lower conductivity but higher sorptivity.

Q4: When is Philip's Equation most applicable?
A: Philip's Equation is particularly useful for short to medium duration infiltration events and provides good estimates for many practical applications in hydrology and agriculture.

Q5: Are there limitations to Philip's Equation?
A: The equation assumes homogeneous soil properties and may not accurately represent infiltration in layered soils or under extreme conditions such as very dry initial conditions or prolonged infiltration events.