Lower Charles River bathymetry : 108 years of fresh water

Abstract

The Lower Charles River has been a heavily utilized urban river that runs between Cambridge and Boston in Massachusetts. The recreational usage of the river is dependent on adequate water depths and there have been no definitive prior studies on the sedimentation rate of the Lower Charles River. The river transitioned from tidal to a freshwater basin in 1908 and the study area for historical comparisons was from the old Charles River Dam to the Boston University Bridge. This study surveyed the river, digitized three prior surveys that spanned 114 years, calculated volumes and depth distributions for each survey, and estimated sedimentation rates from fits to the volumes over time. The average sedimentation rate is estimated as 5-10 mm/year, which implies 1.8-3.5 feet sedimentation since 1908. Sedimentation rates and distributions are necessary to develop comprehensive management plans for the river.