Green and Ampt Infiltration Simulation: Sharp Wetting Front Movement


To simulate Green and Ampt infiltration with the movement of a sharp wetting front, you can follow the steps outlined below. This approach involves solving the Green and Ampt infiltration equation and simulating the movement of the wetting front through the soil profile using numerical methods.

1. **Green and Ampt Infiltration Equation**:
- The Green and Ampt model estimates the cumulative infiltration, F, over time for a given rainfall intensity, soil properties, and initial conditions. The model equation is given by:
\[ F = \phi_s + (K_s \cdot t) + \psi \cdot \log\left(\frac{F}{\phi_s} + 1\right) \]
where:
- \( F \) = cumulative infiltration (depth of water per unit area)
- \( \phi_s \) = sorptivity (infiltration rate at the wetting front)
- \( K_s \) = saturated hydraulic conductivity
- \( t \) = time
- \( \psi \) = soil suction head

2. **Wetting Front Movement**:
- Implement a numerical method, such as finite differences or finite elements, to solve the Richards equation or similar unsaturated flow equations. The Richards equation describes the movement of water in unsaturated soils and can be used to track the propagation of the wetting front over time.
- The sharp wetting front assumption can be incorporated by considering a discontinuity in moisture content and pressure head at the advancing front.

3. **Boundary Conditions**:
- Define the boundary conditions for the infiltration simulation, including the initial moisture content distribution, the infiltration rate at the soil surface, and the boundary conditions for the movement of the wetting front (e.g., initial and boundary pressure heads).

4. **Numerical Solution**:
- Utilize an appropriate numerical solver to discretize and solve the transient flow equation governing the movement of the wetting front. This involves updating the moisture content and pressure head profiles within the soil domain as the wetting front advances due to infiltration.

5. **Simulation Time Frame**:
- Define the simulation time frame and time steps for the transient simulation. The time steps should capture the evolution of the wetting front and the associated changes in moisture content and pressure head within the soil profile.

6. **Visualization and Analysis**:
- Visualize the simulated movement of the wetting front and the resulting changes in moisture content and pressure head over time. Analyze the spatial and temporal dynamics of the wetting front movement and its impact on infiltration and soil moisture distribution.

By following these steps, you can simulate Green and Ampt infiltration with the movement of a sharp wetting front, providing insights into the dynamics of unsaturated flow and the resulting changes in soil moisture content and groundwater dynamics.

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