Generation of Boat Traffic Data: Techniques for Temporal and Spatial Extrapolation

Boat wave induced erosion can be a major concern in rivers and other navigable waterways. When they reach the banks, boat-generated waves can produce velocities and shear stresses near the water surface much larger than those generated from streamflow. This is mainly due to the high level of turbulence produced by wave breaking. Recurrent wave action along cohesive banks due to boat traffic may cause undercutting and eventual failure. Estimation of the relative contribution of boat waves to stream bank erosion requires the knowledge of the spatial and temporal distribution of instances of boat passage in addition to the boat wave properties. Despite of the substantial contribution of boat-induced waves to the bank erosion, the availability of historic boat-wave data for hydraulic modeling purposes is extremely limited. In this study, a partially deterministic method for generating long-term boat-traffic data from a field campaign is presented. Boat-generated wave data (water depth, wave height and wave period) was collected for four months between May, 2015 and September 2015 at three sites along a reach of the Connecticut River, MA. The collected data was then used to predict 15-year boat traffic and boat-wave properties at 25 sites along the same reach of the river, by combining measured daily and weekly variations of boat traffic, together with information on seasonal variations, boat ownership statistics and historic rainfall data obtained form various sources.