Bed morphology adjustment under the impact of a near-bank emergent model vegetation patch

This paper investigated spatial characteristics of bed morphology around a near-bank emergent vegetation patch. Experimental results showed that patch length and density impacted the spatial scale, orientation and type of pool-bar morphology around the patch. Adjacent to the patch, the pool onset lowest location tended to move upstream as patch length and density increased, quantitatively described by a power function involving the two factors; the transverse bed topography along the pool was described by a two-zone scaling model, providing prediction models for the pool morphology, particularly for narrow urban channels. Moreover, we identified, in the patch wake, two types of bars formed meditated by patch length. Short-point and elongated bars formed under short and long patches, respectively, attributed to different mechanisms of flow–sediment-patch interaction, offering new insights into wake depositional trends and streamwise vegetation succession during different vegetation growth stages. The gained knowledge is useful for vegetation-based urban channel restoration.