Observations on Characteristics of Washed Away of Young Salicaceae by Flash Flow From Satsunaigawa Dam

Abstract

Vegetation in rivers causes serious problems such as increases in flood risk due to water level rise during flood. Salicaceae trees are dominant on flood plains and sand bars of rivers in cold and snowy Hokkaido. Therefore, it is crucially important to inhibit the growth of salicaceae trees for river management. While there is a problem that salicaceae trees are flourishing in the Satsunai River, one plant species in the family salicaceae, chosenia arbutifolia, is losing its habitat. Chosenia arbutifolia is registered in the red data book of Japan. Hokkaido Development Bureau, the management authority, is performing field experiments to sweep away young salicaceae, and to form fluvial bars covered with gravel by artificial flash flood with the use of snow melting water released from Satsunaigawa Dam. Authors studied the habitat situations of young salicaceae and chosenia arbutifolia before and after an artificial flash flood, and relations between hydraulic conditions and habitat of the plants.

The role of riparian vegetation flexibility in a bio‐hydro‐morphodynamic simulation

“…Sediment diameter within the river reach was set to 4 mm (Takebayashi & Egashira, 2001). Grain size varies even in rivers with similar characteristics (e.g., slope and width), and differences in bed material mobility may affect the survivability of vegetation (Yanagiya et al, 2014). To clarify the impact of grain size, finer (down to 1 mm) and larger (up to 10 mm) simulations were also conducted.…”