Penobscot River Hydraulics

3D Hydraulics of the Penobscot River and its Aquatic Habitat

Following the 2013 removal of the Veazie Dam in the lower Penobscot River, the reappearance of remnant logging structures (“boom islands”) in the former dam impoundment raises questions about what should be done, if anything, with the derelict structures. Knowledge about the impacts of the boom islands on federally-protected diadromous fish species will help to inform decision-making efforts about dam removal projects involving remnant infrastructure. Detailed knowledge of the water flow velocity conditions around boom islands is central to assessing the impact of logging industry infrastructure on fish habitat, but there are challenges associated with direct measurements and numerical approaches to predicting their hydraulic effects. While detailed velocity measurements are possible with Acoustic Doppler Velocimetry, collecting measurements over a range of flow conditions in large rivers reaches is impractical. Traditional approaches to numerical modeling of river hydraulics are able to perform 1D and 2D simulations in reach-scale domains, but they are unable to capture the effects of the boom islands due to constraints on dimensionality and resolution. Three-dimensional (3D) computational fluid dynamics (CFD) solutions accelerated by High-Performance Computing make it possible to capture the 3D effects of the boom islands on river velocity at the scale of the boom island structures. By using 3D velocity measurements with an Acoustic Doppler Current Profiler (ADCP) to augment and constrain 3D CFD solutions calculated using Smoothed Particle Hydrodynamics (SPH), we will capture detailed information about flow kinematics in the Penobscot River to inform decision-making efforts related to aquatic habitat restoration.