6.5 Problem Set
- Water is ponded at a constant depth of 2.5 cm on a silt loam soil which had an initial water content of 0.15 cm3 cm-3. The water content of the wetted soil above the wetting front is 0.49 cm3 cm-3, and the wetting front has a pressure head of -17 cm. The hydraulic conductivity of the wetted soil is 0.65 cm h-1. Apply the Green-Ampt model for ponded infiltration to answer the following questions:
- What is the infiltration rate (cm h-1) when the wetting front reaches a depth of 30. cm?
- In total, how much water (cm) has infiltrated by that time?
- How long did it take (h) for the wetting front to reach that depth?
- For that same soil with the same initial condition, consider the infiltration process for rainfall at a constant rate of 1.5 cm h-1. Use the Mein and Larson modification of the Green-Ampt model to answer the following:
- How deep is the wetting front (cm) when ponding begins?
- In total, how much water (cm) has infiltrated by that time?
- How long did it take (h) before ponding occurred?
- Repeat problem 2 but this time use a hydraulic conductivity of 0.325 cm h-1, exactly half of the value used previously.
- How deep is the wetting front (cm) when ponding begins?
- In total, how much water (cm) has infiltrated by that time?
- How long did it take (h) before ponding occurred?