Modeling Dune Roughness in a Large Sand-bedded River – Year two

Dunes are common bed features in large sand-bedded rivers and are significant sources of in-channel roughness. Reliably estimating roughness is crucial for the prediction of flood flows, but roughness is crudely represented in hydraulic models widely used by environmental consultants and engineers. Roughness is treated as a calibration knob in these models, adjusted to force predicted water levels to match observations. This makes water level predictions during floods difficult, especially for flows beyond the range of previous observations. The proposed project will examine the physical basis for dune-related roughness in rivers. Previous bed surveys from the sand-bedded Fraser River will be compiled and dune characteristics (height, length, lee angle) will be extracted. Roughness from model calibrations will be compared to observed dune dimensions. Recently proposed relations for predicting dune dimensions, developed separately, will be refined using the field observations and validated with some new field observations. Modules for existing hydrodynamic and morphodynamic models will be developed that incorporate the new predictive relations for roughness. The project will reduce reliance on time-consuming roughness calibration exercises.

Faculty Supervisor:

Jeremy Venditti

Student:

Ryan Bradley

Partner:

Northwest Hydraulic Consultants Ltd.

Discipline:

Geography / Geology / Earth science

Sector:

Professional, scientific and technical services

University:

Simon Fraser University