Porosity Of Soil Given Infiltration Capacity From Green-Ampt Equation Calculator

Green-Ampt Equation:

\[ \text{Porosity} = \left( \frac{\text{Infiltration Capacity at Any Time t}}{\text{Darcy's Hydraulic Conductivity}} - 1 \right) \times \frac{\text{Cumulative Infiltration Capacity}}{\text{Capillary Suction at Wetting Front}} \] \[ \eta = \left( \frac{f_p}{K} - 1 \right) \times \frac{F_p}{S_c} \]

Infiltration Capacity at Any Time t (f_p):

cm/h

Darcy's Hydraulic Conductivity (K):

cm/h

Cumulative Infiltration Capacity (F_p):

cm/h

Capillary Suction at Wetting Front (S_c):

Porosity (η):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the Green-Ampt Equation?

The Green-Ampt equation is a simplified model for estimating infiltration into soils. It provides a physical basis for understanding water movement in unsaturated soils and is widely used in hydrology and soil science.

2. How Does the Calculator Work?

The calculator uses the Green-Ampt equation:

\[ \eta = \left( \frac{f_p}{K} - 1 \right) \times \frac{F_p}{S_c} \]

Where:

\( \eta \) — Porosity (dimensionless)
\( f_p \) — Infiltration Capacity at Any Time t (cm/h)
\( K \) — Darcy's Hydraulic Conductivity (cm/h)
\( F_p \) — Cumulative Infiltration Capacity (cm/h)
\( S_c \) — Capillary Suction at Wetting Front (cm)

Explanation: The equation calculates soil porosity based on infiltration characteristics, hydraulic conductivity, and capillary forces in the soil.

3. Importance of Porosity Calculation

Details: Porosity is a fundamental property of soils that affects water storage, drainage, aeration, and root growth. Accurate porosity estimation is crucial for agricultural planning, groundwater studies, and environmental engineering.

4. Using the Calculator

Tips: Enter all values in the specified units. Infiltration capacity, hydraulic conductivity, and cumulative infiltration capacity should be in cm/h. Capillary suction should be in cm. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range of porosity values for different soil types?
A: Porosity typically ranges from 0.25-0.45 for sandy soils, 0.40-0.60 for loamy soils, and 0.45-0.70 for clayey soils.

Q2: How does porosity affect water movement in soil?
A: Higher porosity generally allows for greater water storage and movement, while lower porosity restricts water flow and increases runoff potential.

Q3: When is the Green-Ampt equation most accurate?
A: The equation works best for uniform soils with clearly defined wetting fronts and under constant rainfall or ponding conditions.

Q4: What are the limitations of this equation?
A: The model assumes homogeneous soil properties, constant hydraulic conductivity, and may not accurately represent layered or structured soils.

Q5: How does capillary suction vary with soil texture?
A: Capillary suction is larger for fine-grained soils (clays) due to smaller pore sizes and smaller for coarse-grained soils (sands) with larger pores.