Jill Singer, Patrick McLaren
Monday 29 june 2015
15:05 - 15:20h at Oceania (level 0)
Themes: (T) Sediment management and morphodynamics, (ST) River morphodynamics
Parallel session: 2B. Sediment - River
Due to environmental problems, including contaminated sediment, both the Buffalo and Fox Rivers have been identified as Great Lakes Areas of Concern. Both rivers also are currently undergoing environmental restoration, a major component of which involves the removal of contaminated sediment. Our work focuses on STA, a kinematic model that differs from the dynamic approach in that the former is based on observations (the grain-size distributions of the sediments), whereas the latter requires assumptions of the probable processes responsible for sediment erosion, transport and deposition. STA examines the relative changes in the grain-size distributions of the substrate from which the sediment transport patterns and depositional behavior can be obtained. In the Buffalo River, the derived patterns of sediment transport revealed the importance of Lake Erie wind-driven surges that elevate lake level at the east (Buffalo) end of the lake. Surges can propagate in the direction opposite to the river's flow direction and are capable of transporting sediment upriver, a process recognized, but not taken into account in river management decision-making. In applying STA to assess cleanup litigation issues in Green Bay it was discovered that wind-driven surges are also important, but had largely been overlooked as an important process capable of reversing the flow direction of the Fox River. In both rivers, STA successfully delineated sediment transport pathways and revealed complex patterns of sediment transport. The findings were also used to assess the validity of dynamic models illustrating the value of kinematic modeling and its place in river restoration decision-making.