DELAWARE RIVER MODEL STUDY. DIKE REHABILITATION. HYDRAULIC MODEL INVESTIGATION.

The existing comprehensive fixed-bed model of the Delaware Estuary was used to determine the necessity for rehabilitating the Reedy Island and Pea Patch Island training dikes. These dikes, located adjacent to the navigation channel in the lower reaches of the Delaware River, are about 50 and 30 years old, respectively, and certain sections have deteriorated to such an extent that the cost of raising the dikes above mean high water is estimated to be about 10 million dollars. Model tests were conducted to determine the effects of various degrees of dike rehabilitation and destruction on hydraulic conditions throughout the affected area of the estuary. The test results consist primarily of current velocity measurements and time-exposure photographs of surface-current patterns. From this information it was concluded that rehabilitation of the dikes was not justified either by benefits to navigation or by decreased maintenance dredging in the navigation channel. (Author)