3. (20%) (1) Show that the cumulative infiltration under ponded conditions by the Green-Ampt equation as: F= K(t-t)+F+A0 In VAB+ F AO+Fp (2) Determine the time (t) and infiltration rate (f) when the cumulative infiltration F-5 cm with a constant rainfall rate event (3 cm/hr for 3 hours) and a silt loam soil with an effective saturation 35% (effective porosity-0.486, wetting front soil suction head-16.68 cm, and hydraulic conductivity=0.65 cm/hr). (Hint: calculate the ponding time t, at first)