The existence of grasses increases the resistance of the ground, and thus decreases the flow velocity and produces energy loss. In this study, the governing equations of flow were nondimensionalized,based on the Biot’s poro-elasticity theory. These equations were solved analytically.The flow region was divided into three layers--homogenous water, vegetation and permeable soil.The velocity distribution and the shear stress distribution were analytically derived and were discussed for understanding of the flow mechanism. The shear stress distribution showed that when the dimensionless coefficientδ2 approximately equals 9.5 with equivalent depths of water layer and vegetation layer, the shear stresses at the interface between the water layer and vegetation layer and at the ground surface are equal and reach a maximum.
Key Words : Pore fluid, flow velocity distribution, shear stress distribution.