Biological aspects of porous-dike intake structures

Current knowledge is reviewed on the potential for both adult and larval exclusion with a porous dike. It is shown that exclusion is possible, given small enough filter material. In addition, limited observations show that some adult and larval fish will avoid a porous-dike intake, thereby suggesting that dikes can also act as behavioral barriers. Information on fouling and clogging of porous dikes is reviewed, and proposed anti-fouling techniques are discussed. Data are too limited for prediction of flow restrictions due to fouling; however, it is shown that fouling is not a problem when large filter material is used in the dike. To determine the feasibility of a porous-dike intake, a pilot-scale field experiment is proposed. The proposed in-situ test facility, to be installed in Mount Hope Bay, Mass., is described. Plans to assess the exclusion capability and fouling rates of several dike materials are presented. A parallel laboratory program of larval behavioral studies is described. Results of this study are expected in 1981