Engineering Characteristics of Artificial Benthic Reefs at three Sites off Southwestern Coast of Taiwan

摘要

This investigation, which incorporated the knowledge and practices ofrnmarine geotechnical engineering and marine geoacoustical surveying,rncould be split into two phases, i.e., reef subsidence prediction and reefrnstatus observation. The total amount of subsidence for reefs at Yung-An,rnLin-Yang, and Fang-Liau site was predicted to be about 2m, 2.lm, andrn0.65m. The amount of subsidence deduced from side-scan sonarrnobservations was more or less comparable with the predicted value. Inrnaddition, sicouring is the major factor which induced the burial ofrnartificial reefs. The effect of scouring is closely correlated with grainrnsize distribution of sediment. For a reef site with coarse grained,rncohesionless sediment (i.e., Lin-Yang site), burial of artificial reefs wasrnrecognized. Whereas, limited influence of scouring could be observedrnfor a reef site with fine grained, cohesive sediment (i.e., Fang-Liau site).rnFor a site with composite grain size distribution (i.e., Yung-An site), arnprominent topographic depression of about 1.5m was noticed.