Geomorphology report on coastal erosion at the Detention River estuary, Hellyer, North-West Tasmania.

摘要

The western bank of the Detention River estuary has in the last few years suffereduderosion owing to the active estuarine channel meandering to the west. The mainudestuarine channel was located in the centre of the estuary from 1971 to 1997 at least,udand has moved west after 2004 following increased sand deposition in the mouth.udHuman activity in the area is further exacerbating the erosion problem, and fallenudtrees also contribute to sediment erosion. Erosion at this site is not primarily causedudby rise in sea-level, though it exemplifies the types of impacts that widespreadudcoastal areas in Tasmania will experience in coming decades.udRecommendations to mitigate this erosion problem must be agreed by stakeholdersudinvolved, and options include restriction of public access, further removal of largeudwoody debris at the base of the erosion scarp, increasing the sheer strength of theuderosion bank by control of runoff and revegetation, and boat wake restriction in theudestuary. These actions would all decrease erosive forces at the site. Subject to EIAudapproval and supervision by a hydraulic engineer this geomorphologists’ report canudalso support the option of reconstruction of the central estuary main channel at itsudposition around 1988 to 1997, to relieve flow at the erosion site. This might includeudthe option of subsequent beach replenishment of the erosion site, though involvingudno hard structures. Further investigation particularly including GIS analysis and siteudmonitoring should also be carried out.