Thursday 2 july 2015
17:51 - 17:54h at Asia (level 0)
Themes: (T) Hydro-environment, (ST) Impacts of pollutants on the water environment, Poster pitches
Parallel session: Poster pitches: 13G. Environment - Impact
The contaminants will release from streambed to river body after the streambed is polluted due to accidents, leakage of mine, or point and non-point source pollution. The contaminants release from streambed may pollute again the overlying water in the river. Using laboratory experiments and numerical simulations, we investigated that variable density solute release from periodic bed forms. The convection induced by bed forms drives the solute releases from the upper streambed. However the variable density prevents the solute release from lower streambed and has longer tail due to the circulating flow induced by density gradients. Density-driven flow modified the pore water flow patterns and form the circulating flow in the lower streambed. There could be four circulating flows. The low circulating flow makes the bottom of the streambed better mix. It makes the hyporheic zone deeper and bigger. The magnitudes of the density gradients and horizontal pressure gradients induced by river slope have great effects on the circulating flow. The circulating flow may change physical, chemical and biological characteristics.