Relation between sandbar mode and vegetation expansion in sand-bed river

The expansion of riparian vegetation on floodplain has been reported in many Japanese rivers, and it is necessary for river engineers to understand vegetation dynamics for both flood control and ecosystem conservation. In this study, a numerical simulation model was proposed to clarify the relation between bar mode (alternate bar or multiple bar) and vegetation dynamics. The results of the simulation have revealed that the annual maximum discharge of flood is a key factor determining the trend of expansion and destruction of vegetation, and the bar mode influences the expansion rates of vegetation coverage and the degree of tree type vegetation. It is also found that the overgrowth of vegetation yields the morphological change of river such as increase of relative height and immobilization of sand bar.