(b) Two different porous materials are packed in a column with square cross-section 0.2 m × 0.2 m. The hydraulic conductivities of the materials are K1 = 1 × 10^-4 m/s and K2 = 2.5 × 10^-4 m/s and their porosities are φ1 = 0.3 and φ2 = 0.25, respectively. The packed column is fully saturated with water. A layer of water of depth 0.1 m is maintained at the top of the column. Water flows down the column at a constant volumetric flow rate of 4 cm3/s.

(i) What is the Darcy velocity at the top of the column (z = 0.4 m), the interface between the two materials (z = 0.2m), and at the bottom of the column (z = 0) in units of m/s?

(ii) Calculate the hydraulic heads at the top of the column (z = 0.4m), the interface between the two materials (z = 0.2m), and at the bottom of the column (z = 0).