ABSTRACT
Sediment pulses delivered to a river affect downstream reaches of the river network. The movement of sediment depends on the flow, grain size distribution, interactions among grain sizes, bed morphology, as well as the geometry of the channel and the network. This study serves as essential validation for a model of the space-time evolution of sediment pulses and the physical disturbances to downstream reaches of a channel network. The 1D model builds on a previous Lagrangian, bed-material sediment transport model, which is applied to a 27-kilometer reach of the mainstem Nisqually River (WA) draining Mt. Rainier and terminating in Alder Lake. We utilize measured flow and grain size as inputs, and measurements of bed-elevation change and sediment accumulation rates in Alder Lake to validate the model. This study is important because it allows us to better characterize the fluvial geomorphic response of river networks to variations in sediment supply.
