Comment on the paper “An analytical solution for design of bi-level drainage systems” by A.K. Verma, S.K. Gupta, K.K. Singh, H.S. Chauhan

The hierarchy of models applicable to transient free surface problems of ground water flow to drains is discussed. The model choice is related to drain type and dewatering stage. Flow pattern is illustrated to vary with decrease of the water table. Simulation of drains and corresponding boundary conditions are discussed.