VCMP Sites - Shorelines

VCMP Sites - ShorelinesThe Shorelines dataset features short-term and long-term shorelines across sites monitored by the Victorian Coastal Monitoring Program (VCMP) along Victoria's coastline, spatially represented as polyline data.The VCMP drone survey short-term outputs include shorelines for each survey, taking the ‘shoreline’ as the +1 m AHD contour for Open Coast sites, and +0.5 m AHD contour for large bay sites.Output products include 1m Digital Surface Models (DSM) and Orthophotos (vegetation is included in UAV data).- Vertical uncertainty for the output digital surface model (DSM) is estimated at 0.1 m. - The shoreline proxy is defined as the point at which each transect first intersect a given contour (m, AHD): 1.0 m AHD for open coasts and 0.5 m AHD for bay sites - Intersection points are joined alongshore to create a shoreline, noting the alongshore spacing (30-m) may be too low to define complex, small-scale features. - Assuming a beach face slope of 1-in-10, a 0.1 m vertical uncertainty in the survey DSM equates to cross-shore uncertainty of 1 m in shoreline position.Digital Earth Australia (DEA) coastlinesA mean annual mid-tide shoreline is extracted from satellite imagery using sub-pixel identification methods, for the period 1988 to 2021, at 30-m alongshore spacing (Bishop-Taylor et al., 2021). - DEA shorelines have an estimated uncertainty of 1-3 m, with a precision limit on shoreline trends of 0.31 m/yr, i.e., trends below this threshold are insignificant. - DEA have known issues around cliffed areas, leading to higher (unconstrained) uncertainty in some cliffed areas. DEA outputs in such areas should be treated with caution.Aerial Imagery ShorelinesAerial images are hosted and geo-rectified by DEECA's Coordinated Imagery Program. Based on control point checks by VCMP, newer images (approx. post-2000) are estimated to have horizontal uncertainty of 3-m or less. Older images (pre-2000) can have greater uncertainty, estimated at up to 10-m. Older images (