Hahoe, a historical village, is famous for two large nonvegetated sandbars. These sandbars have become covered with vegetation after construction of the two upstream dams. To identify the contributing factors to vegetation recruitment, flow regime, soil moisture, flood intensity and climate conditions before and after two dams were investigated. The occurrence of drought caused flow change and significant encroachment of riparian vegetation in just 3 years after the second dam was in place. Numerical results show that the dimensionless shear stress was a useful factor for predicting vegetation recruitment. Decrease in peak flows and aggradation of the sandbars resulted in more of the sandbar area experiencing low shear stress, hence facilitating vegetation colonization. In conclusion, the development of optimal dam operation rule to increase the difference of peak release flows between germination and flood season may be required to manage the riparian vegetation sustainably and economically in the regulated river.