Norfolk Harbor and Channels Deepening Study. Report 1. Physical Model Results. Chesapeake Bay Hydraulic Model Investigation

摘要

This report presents the findings of physical model tests of deepening the approach channels to Norfolk and Newport News, Virginia. The tests included a steady-state portion for the determination of the tide and current velocity effects of channel deepening as well as dynamic portion where variable tide and freshwater inputs were used to study salinity redistributions. The steady-state tests showed that tides would remain unaffected by channel deepening while the velocity studies indicated some subtle changes caused by the deepening. An overall decrease in velocity amplitude of 0.13 fps was noticed in the deepened condition. This decrease, however, was barely detectable by model instrumentation. Slight increases in flood predominance were noticed under average inflow conditions indicating that salinity intrusion may move upstream in the study area. Results of the tests indicate salinity changes to the estuary which can be attributed to channel deepening. On the average, the changes are small, normally less than 2 ppt, in an extremely dynamic portion of the estuary where natural salinity fluctuations due to variations in tides and freshwater input can cause weekly variations an order of magnitude greater.