Green Ampt Equation Calculator

Green Ampt Equation:

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

Darcy's Hydraulic Conductivity (K):

cm/h

Porosity (η):

Capillary Suction at Wetting Front (Sc):

Cumulative Infiltration Capacity (Fp):

cm/h

Infiltration Capacity at Any Time t (fp):

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1. What is the Green Ampt Equation?

The Green Ampt equation is a simplified physical model for estimating infiltration capacity in soils. It provides a mathematical representation of water infiltration into unsaturated soils based on soil properties and initial conditions.

2. How Does the Calculator Work?

The calculator uses the Green Ampt equation:

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

Where:

\( f_p \) — Infiltration capacity at any time t (cm/h)
\( K \) — Darcy's hydraulic conductivity (cm/h)
\( \eta \) — Porosity (dimensionless)
\( S_c \) — Capillary suction at wetting front
\( F_p \) — Cumulative infiltration capacity (cm/h)

Explanation: The equation accounts for the effect of soil properties and moisture conditions on the rate at which water infiltrates into the soil.

3. Importance of Infiltration Capacity Calculation

Details: Accurate infiltration capacity estimation is crucial for hydrologic modeling, irrigation planning, flood prediction, and understanding groundwater recharge processes.

4. Using the Calculator

Tips: Enter Darcy's hydraulic conductivity in cm/h, porosity (between 0-1), capillary suction, and cumulative infiltration capacity in cm/h. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is Darcy's hydraulic conductivity?
A: Darcy's hydraulic conductivity measures soil's ability to transmit water, which is vital in understanding groundwater flow and environmental processes.

Q2: How does porosity affect infiltration?
A: Higher porosity generally allows for greater water storage and potentially higher infiltration rates, depending on pore connectivity.

Q3: What is capillary suction at wetting front?
A: Capillary suction at wetting front is due to capillary attraction in soil voids and is large for fine-grained soils such as clays and small for sandy soils.

Q4: When is the Green Ampt equation most applicable?
A: The equation works best for uniform soils with clearly defined wetting fronts and under constant rainfall intensity conditions.

Q5: What are typical values for these parameters?
A: Hydraulic conductivity varies widely (0.01-10 cm/h for most soils), porosity typically ranges 0.3-0.6, and capillary suction ranges from 5-50 cm depending on soil texture.