Validation of a three-dimensional numerical model using field measurements in a large scale river reach

A three-dimensional numerical model is developed to resolve the flow in natural rivers, in particular in the vicinity of hydraulic structures. The model solves the Reynolds Averaged Navier Stokes (RANS) equations in generalized curvilinear coordinates. It is currently being applied to a river reach approximately seven kilometers (four and half miles) long in Columbia River, WA, immediately upstream of Wanapum Dam. The model has been calibrated against field measurements for two flow discharges. The higher discharge (5390 m3s) is split between the powerhouse and the spillway, while the lower discharge (2559 m3s) is released only through the powerhouse. The field measurements are collected at six cross sections. At each vertical velocity-station, three velocity components were measured at 0.2, 0.4, and 0.8 of the flow depth. A comparison between the numerical solutions and the field data is presented, and a good agreement is observed. The obtained level of agreement indicates that the numerical model produces results that are quite satisfactory for practical purposes.