The Hydrography of Barnstable Harbor, Massachusetts1

Barnstable Harbor, on the north shore of Cape Cod, Massachusetts, originated from the growth of an offshore barrier bar across an indentation of the coastline. In common with many other East Coast tidal embayments of similar origin it has: 1) low runoff, carried by a few small streams, which together with direct rainfall and groundwater seepage provides a total freshwater acquisition that is small compared to the tidal prism volume; 2) essentially marine internal aquatic environments; and 3) extensive salt marshes drained by tidal creek systems. The hydrography of the harbor is largely determined by the internal arrangement of its shoals and channels. The shoals and channels act as dams and weirs, distorting the tides until they approximate those found in typical river estuaries. The tidal distortion results in a time asymmetry of the maximum currents which in turn produces a net up‐harbor transport of sediments, despite the fact that the ebb currents are of the greater velocity. The hydrography of the harbor in spring, summer, and fall is described. Parameters discussed include salinity, temperature, transparency, water masses, tidal currents, sediment analyses, the salinity relations of intertidal flats, and some aspects of the annual temperature regime.