Vegetation is an important feature of many rivers. Vegetation along rivers produces high resistance to flow and, as a result, has a large impact on water levels in rivers and lakes. The effects of instream-unsubmerged vegetat ion (such as the reed-similar Kalmus) on flow resistance and velocity distribut ions is studied in the paper. Artificial vegetation is used in the experimental study to simulate the Acorus Calmus L. As shown in experimental tests the re sist ance depends strongly on vegetation density and the Manning resistance coef ficient varies with the depth of flow. A simplified model based on concepts of d rag is developed to evaluate the roughness coefficient (Manning’s n) for no n-submerged vegetation. In vegetated channels the overall flow resistance is in fluenced significantly by the distribution pattern of the vegetated beds. Within vegetation, vertical variation in velocity is different from that in the non-v egetated bed, which reflects the variation in vegetation density. Vertical turbu lent transport of momentum is negligible as demonstrated by experiments. Vegetation is an important feature of many rivers. Vegetation along rivers produces high resistance to flow and, as a result, has a large impact on water levels in rivers and lakes. The effects of instream-unsubmerged vegetat ion (such as the reed-similar Kalmus) on flow resistance and velocity foliage is studied in the paper. Artificial vegetation is used in the experimental study to simulate the Acorus Calmus L. As shown in experimental tests the re sist ance depends strongly on vegetation density and the Manning resistance coef ficient varies with the depth of flow. A simplified model based on concepts of rag is developed to evaluate the roughness coefficient (Manning’s n) for no n-submerged vegetation. In vegetated channels the overall flow resistance is in fluenced significantly by the distribution pattern of the vegetated beds. Within vegetation, vertical variation in velocity is different from that in the non-v egetated bed, which reflects the variation in vegetation density. Vertical turbu lent transport of momentum is negligible as demonstrated by experiments.