||New England Electric System, Westborough, MA. ;Marine Research, Inc., Falmouth, MA.;Environmental Protection Agency, Research Triangle Park, NC. Air and Energy Engineering Research Lab.
The report gives results of an evaluation of a porous dike intake. A small-scale test facility was constructed and continuously operated for 2 years under field conditions. Two stone dikes of gabion construction were tested: one consisted of 7.5 cm stones; and the other, 20 cm stones. Approach velocity was set at 3 cm/sec. Using a test flume, laboratory studies were also conducted on the avoidance response of fish to a porous dike intake. Flow through a porous dike, induced by a hydraulic head of about 61 cm, depended on the cross-sectional area (tidal height). Throughout the experiment, flow resistance changed, depending on the fouling. Increases in flow resistance resulted in lower flow rates at constant hydraulic head. Flow rates could be increased by backflushing the stone dike. Throughout the experiment, the porous dike showed a steady accumulation of silt and organic matter, but the flow rates tended not to decrease with time.