Open Collections

Abstract

Along Wreck Beach the existing headland cliffs are eroding and receding under attack from terrestrial and marine agents. Valuable property is being lost and nearby structures endangered. Remedial measures were undertaken in the summer of 1974 to halt wave erosion along the cliff base. A rock groin and sand—gravel protective beach scheme was only partially success ful during the following year. To design an adequate protection system for the cliffs wind and wave effects need to be deter mined to fully understand the resulting sand movement patterns. Understanding the processes affecting Wreck Beach is the first step in controlling them. Methods used to investigate sand movement included field coverage of the study area in photographic form as well as instrument cross—sectioning over a two year period. These data were correlated with historical wind records and predictions from wave refraction diagrams to determine seasonal movement onto and off the beach face and the cyclic progression of sandbars in the longshore current direction. Annual sand trans port volumes, sand supply sources and amounts contributed are outlined. In designing a protection scheme in which longshore trans port requirements must be considered the information and calcu lations suggests that the Fraser River North Arm could amply provide the longshore transport supply requirements. However, some means in addition to the present natural processes must be available to bring this sand into a range where wind gen erated wave activity can incorporate it into the existing Wreck Beach system.