Flow and wake characteristics associated with riparian vegetation patches: Results from field?scale experiments

Riparian vegetation patches growing on river banks and floodplains influence in-channel overbank hydromorphological processes. The current knowledge patch-scale hydrodynamics is largely based laboratory flume experiments with simplified vegetation. aim of this study to provide new understanding the flow wake characteristics for real riparian field-scale natural willows, in order inform ecological modelling. focus was placed effects foliage as main driver seasonal changes flexibility-induced reconfiguration around patches. patch drag, defined by its blockage factor, increased 3.0–4.4 times presence decreased up 60% because streamlining increasing velocity. Such large drag altered characteristics, affecting onset a vortex street. Seasonality flexibility modified sheltering effect, that is, magnitude velocity, turbulent kinetic energy, bed shear stress reduction wake, relative background level. In foliage, mean velocity were reduced average ~50% ~70%, respectively. effect lower leafless conditions than foliated conditions. For cases, spatial extents over-depth near-bed sheltered region 1.5 1.8 larger corresponding Overall, mechanisms identified key controls associated vegetation, major implications developing models predicting processes potential preserve create habitats.