6) Water at 20°C flows through a vertical sand column (grain diameter = 0.5 mm) of length 120 cm and cross section area A = 200 cm². The difference between water levels at the inflow and the outflow reservoirs is 120 cm. The porosity of the sand is n = 0.36. The hydraulic conductivity is k=20 m/day. Kinematic viscosity of water at 20°C is 1.3 x 106 m2/sec. Estimate: 1) Is Darcy's law applicable for this system? 2) What is the total discharge Q? 3) What is the Darcy flux or specific discharge q? 4) What is the average transport velocity in this column? 5) What is the hydraulic gradient along this column?