The Geomark datasets are spatial reference files that describe the feature, its location and its name. Examples of the types of features included in these datasets are: rivers, water bodies, railway lines, parks, airports, hospitals, education centres, emergency facilities, sport facilities, mountains, transport infrastructure, power facilities and community venues (but not road names). The data contained within the individual Geomark datasets has been sourced from Vicmap Elevation, Vicmap Hydro, Vicmap Features of Interest and Vicmap Transport. The difference between the features in these Vicmap datasets and Geomark is that the Geomark features have been combined to create one piece of geometry based on its name and type. GEOMARK_POINT : A statewide point dataset containing information for “named” or “could be named” features. Points represent relatively small area features that have been generalised or larger features where the spatial source is a coordinate or an address. Examples of small area point entities include wind turbines, snow poles, and emergency markers. GEOMARK_LINE : A statewide line dataset containing information for “named” or “could be named” features. Linear features include rivers, power lines, chairlifts and pipelines among others. GEOMARK_POLYGON : A statewide polygon dataset containing information for “named” or “could be named” features. Polygons represent larger area features that have been captured in more detail. Examples include lakes, sports grounds, gardens, parks and shopping precincts. GEOMARK_INDEX_CENTROID : A statewide centroid dataset holding one centroid record for each feature (unique feature id) held within the Geomark Index Extent table. GEOMARK_INDEX_EXTENT : A statewide polygon dataset holding one polygon or multi part polygon record for each feature (unique feature id) held within the Geomark Point, Line and Polygon tables. Note: point and line features are represented as polygons.

## **Abstract** This dataset and its metadata statement were supplied to the Bioregional Assessment Programme by a third party and are presented here as originally supplied. DEPI originally engaged GHD to develop seamless 3D aquifer surfaces for the Victorian Aquifer Framework (VAF). The seamless mapping of aquifers across the state provides the fundamental framework for groundwater resource management, underpins development of a revised management structure for Victoria (the Secure Allocation Future Entitlement project funded by the National Water Commission) and contributes to the data needs of the Bureau of Meteorology National Groundwater Information System (NGIS). The original dataset was produced by GHD in 2012 using (in part) data provided by Southern Rural Water Corporation and Goulburn-Murray Water Corporation. It has been subsequently amended by Hocking et al and SKM in 2013. ## **Dataset History** A number of key input datasets were sourced as part of the process to derive the 3D aquifer surfaces. These datasets included: The DEPI State-wide Stratigraphic Database (SSD); The National Groundwater Information System (NGIS) database containing groundwater borehole location information as well as lithological and stratigraphic information; Raster layers previously produced for Southern Rural Water (SRW) by SKM and GHD in 2009; The crystalline basement surface provided by the former Department of Primary Industries (DPI); Outcrop 1:250,000 scale geological mapping compiled by the former Geological Survey of Victoria, DPI; A state-wide 100m Digital Elevation Model (DEM) based on the DEPI 20m DEM. This was used to represent the natural surface; Data generated using DEPI's state-wide ecoMarkets groundwater modelling package to assist with the definition of key layers of the major Cainozoic aquifers; Latrobe Valley Coal Model which was used to provide a framework for the hydro-stratigraphy of the wet Gippsland Basin; Rasters of the top elevation of the major aquifer systems covering the Kiewa, Ovens, Goulburn-Broken and Loddon and Campaspe catchments; Data extracted from the Basin in a Box, the Murray Basin Hydrological Map Series and the Murray-Darling Basin Groundwater Status 1990-2000: Summary Report; Airborne magnetic data publicly available from raster data published by the former Geological Survey of Victoria, DPI. Once the input data had been compiled, the VAF 3D surfaces were developed by lfollowing a number of key steps, summarised below: (1) Contours as polylines and aquifer extents as polygons were extracted from previous mapping surfaces; (2) Outcrop points attributed with values from the DEM were created; (3) Based on the state-wide stratigraphic database, the contours and extents were refined or created; (4) A top elevation raster was interpolated using contours, outcrop points and bore data then replacing outcrop areas with the DEM; (5) The aquifer thickness was then checked in GIS by comparing layers against each other and assessing for cross-overs and negative thickness; (6) The input data was then revised and bore data, contours, and aquifer extents modified as required due to errors in the thickness; (7) If there were subsequent issues identified such as overlaps between aquifers, mismatches between bores and resulting layers, then the process was revised by returning to Step (3); (8) If the layers were matching well, then extent points were created to smooth layers at the edges; (9) A top elevation raster was generated again using contours, outcrop points, extent points and bore data; (10) The aquifer thickness was checked again, and if significant issues were identified, then the process returned back to Step (3) for further iteration; (11) Further modifications were applied to remove negative thicknesses and to provide minimum thickness of overburden; (12) Top and bottom elevation rasters were then generated at 100m pixel resolution to form the final dataset. In generating each of the layers, a number