Green-Ampt Infiltration Parameters: Difference between revisions
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== Green-Ampt Infiltration ==
The Green-Ampt approach varies the rate of infiltration over time based on the soil’s hydraulic conductivity, suction, porosity and initial moisture content. The method assumes that as water begins to infiltrate the soil, a line is developed differentiating between the ‘dry’ soil with moisture content θ<sub>i</sub> and the ‘wet’ soil (with moisture content equal to the porosity of the soil η). As the infiltrated water continues to move through the soil profile in a vertical direction, the soil moisture changes instantly from the initial content to a saturated state. This concept is shown schematically in Figure 1.<br>
Note: The Green-Ampt approach is appropriate for simulating single rainfall events where evapotranspiration and gravity-driven drainage are not significant. The 2023-03 release introduced functionality in TUFLOW HPC to allow for horizontal movement of soil water, enabling long-term simulations with multiple rainfall events. To support this, a change was implemented in the Green-Ampt equation to account for changing initial soil moisture and cumulative infiltration over time. For further details, see Section 7.3.7.1.1 Green-Ampt (GA) in the [https://docs.tuflow.com/classic-hpc/manual/2025.1/TwoD-Domains-1.html#GA-5 <u>TUFLOW Manual</u>].▼
[[File:Fig_1_GA_Model.png|300px|Figure 1 Green-Ampt Model Concept]]<br>
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:F(t) is the cumulative infiltration calculated from:<br>
[[File:Accumulative_infil.png|350px]]<br><br>
▲Note: The Green-Ampt approach is appropriate for simulating single rainfall events where evapotranspiration and gravity-driven drainage are not significant. The 2023-03 release introduced functionality in TUFLOW HPC to allow for horizontal movement of soil water, enabling long-term simulations with multiple rainfall events. To support this, a change was implemented in the Green-Ampt equation to account for changing initial soil moisture and cumulative infiltration over time. For further details, see Section 7.3.7.1.1 Green-Ampt (GA) in the [https://docs.tuflow.com/classic-hpc/manual/2025.1/TwoD-Domains-1.html#GA-5 TUFLOW Manual].
United States Department of Agriculture (USDA) soil types have been hardwired into TUFLOW and are presented in Table 1 along with the soil parameters. Alternatively, it is possible to define a customised soil type by specifying user defined values within the tsoilf.<br>
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