1 Water is ponded at a constant depth of 25 cm on a silt loam soil that had an initial water content of 015 cm3 cm-3 The water content of the wetted soil above the wetting front is 049 cm3 cm-3 and th

To answer these questions, we can use the Green-Ampt model for ponded infiltration. The Green-Ampt equation is given by:

I = (K * (Ψf - Ψi)) / (t + (K * h))

Where: I = Infiltration rate (cm/h) K = Hydraulic conductivity of the wetted soil (cm/h) Ψf = Pressure head at the wetting front (cm) Ψi = Initial pressure head (cm) t = Time (h) h = Depth of ponded water (cm)

a. To calculate the infiltration rate when the wetting front reaches a depth of 30 cm, we need to substitute the values into the Green-Ampt equation:

I = (0.65 * (-17 - 0.15)) / (t + (0.65 * 2.5))

We need to solve for t when the wetting front reaches 30 cm. Rearranging the equation, we get:

t + (0.65 * 2.5) = (0.65 * (-17 - 0.15)) / I

Substituting the values, we have:

t + 1.625 = (-11.05) / I

Now, when the wetting front reaches 30 cm, t will be the time it took to reach that depth. This can be calculated by substituting the values into the equation and solving for t:

t + 1.625 = (-11.05) / I t = (-11.05) / I - 1.625

b. To calculate the total amount of water infiltrated by that time, we can multiply the infiltration rate (I) by the time (t):

Total water infiltrated = I * t

c. To calculate the time it took for the wetting front to reach a depth of 30 cm, we can use the equation derived in part a:

t = (-11.05) / I - 1.625

Now, let's substitute the given values and solve the equations:

a. Infiltration rate (I) when the wetting front reaches 30 cm: I = (0.65 * (-17 - 0.15)) / (t + (0.65 * 2.5))

b. Total water infiltrated by that time: Total water infiltrated = I * t

c. Time it took for the wetting front to reach 30 cm: t = (-11.05) / I - 1.62