Modelling And Application Of One-Dimensional River Ecosystem Model.

---

Yoshihisa Akamatsu, Hiroyuki Nagano

Tuesday 30 june 2015

14:50 - 15:05h at Amazon (level 1)

Themes: (T) Hydro-environment, (ST) Ecohydraulics and ecohydrology

Parallel session: 6G. Environment - Ecosystem

---

In the river assessment, it is necessary to discuss the mass balance in the river ecosystem using river ecosystem model. The ecosystem model is developed to know the material balance in the river ecosystem, which consists of one-dimensional unsteady flow, one-dimensional calculation of bed variation, heat balance, water quality and biological model. Fish, aquatic animal and attached alga are taken into account in this ecological model. This model was applied to Saba River, in Japan, where water quality and biological environment have been observed at five points in the river basin in two month intervals over one year. The temporal variations of water level, water temperature, dissolved oxygen and the amount of attached algae obtained from this model in the ordinary flow show a good agreement with the observed results. In the flood, the observed riverbed deformation was a little smaller than the calculated. However, it is enough to evaluate the influence of sediment transport on the habitat of fish, aquatic animal and attached alga. These results reveal that this model is useful to predict the variation of material balance in the river ecosystem due to the climate change and the river crossing structure such as weir and dam.