Abbreviations and acronyms ABS Australian Bureau of Statistics AEM Airborne Electromagnetic AGSO Australian Geological Survey Organisation ANRA Australian Natural Resource Atlas AHD Australian Height Datum AOI Area of Interest APT Aquifer Parameter Table BRS Bureau of Rural Sciences CD Collector District CSA Case Study Area CVI Coastal Vulnerability Index Commonwealth Scientific and Industrial Research Organisation Australian Department of Climate Change and Energy Efficiency DEM Digital Elevation EC Electrical Conductivity FAO United Nations Food and Agriculture Organisation GA Geoscience Australia GIS Geographic Information System GH Ghyben-Herzberg GMU Groundwater Management Unit IPCC Intergovernmental Panel on Climate Change ISDR International Strategy for Disaster Reduction KMM Knowledge Monitoring and Management MSL Mean Sea NAMS National Agricultural Monitoring System NCGRT National Centre for Groundwater Research and Training NRM Natural Resource Management NT Northern Territory NTC National Centre NSW New South Wales NWC National Commission NWI National Water Initiative 2004 PSC Project Steering Committee PWA Prescribed Area QDNRM Queensland Department of Natural Resources and Mines Qld Queensland RNWS Raising National Water Standards SA South Australia SRTM Shuttle Radar Topographic Mission SWI Seawater Intrusion TDS Total Dissolved Solids TWOH Tidal watertable over-height VFA Vulnerability Factor Analysis Vic Victoria WA Western Australia
Table 1 Summary of a GIS-based analysis of irrigation areas and coastal elevation, after Werner et al. (2008). State irrigation area (ha) Major Land-use Area at 0–5 mAHD (ha) Area at 0–10 mAHD (ha) NSW 867 516 Cropping 7663 10 198 NT 29 899 Tree fruits 136 402 Qld 1 080 787 Sugar cane 15 706 84 749 SA 271 319 Sown grasses 9481 16 839 TAS 128 795 Cropping 2922 6837 Vic 837 886 Modified pasture 9624 23 018 WA 55 789 Vine fruits 528 2814 Total 3 271 991 Cropping 46 060 144 858 Figure 5 Irrigation areas vulnerable to SWI based on the lowest minimum groundwater level (m AHD) recorded for each bore. Note: data not available for the Northern Territory (after Nation et al., 2008). A summary of Australian sites where the threat of SWI has been recognised is shown below in Figure 6 and also listed in Table 2. Further details on these areas follows in Chapter 3.2. Figure 6 Locations where the threat of SWI has been identified. Table 2 Distribution of previous Australian studies that identify the threat of SWI. Location SWI Incidence Reported SWI Monitoring Degree of SWI assessment1 South Australia Eyre Peninsula Yes Yes, but not SWI interface specific Moderate Le Fevre Peninsula (Adelaide) Yes Yes, but not SWI interface specific Low Adelaide Metropolitan Yes Yes, but not SWI interface specific Moderate Port MacDonnell No No Moderate Willunga, SA Yes Yes, but not SWI interface specific Low Victoria Werribee Yes Yes, but not SWI interface specific Moderate Gippsland (Sale and Orbost regions) No No None to Very Low Point Nepean* No No Low Koowerup* No No None to Very Low Moorabbin* No No None to Very Low
Table 3 Summary of literature for areas identified as being vulnerable, or potentially vulnerable, to SWI in Tasmania. Location References Aquifer lithology SWI occurrence reported Driving factors Investigations SWI monitoring SWI management Level of assessment Land / groundwater use Woolnorth (Cradle Coast NRM Committee, 2005) Tertiary limestone Yes (e.g. Cradle Coast NRM Committee, 2005) Groundwater extractions; “saline coastal influences” Limited data No No None to Very Low Not reported King Island (Ezzy, 2003) Quaternary dune sands No Groundwater extractions Limited data No No None to Very Low Town water supply King Island, Grassy scheelite mine site (Dyson, 2006) Proterozoic fractured metasediments No Faults intersected by mining operations at depths below sea level Limited data No No None to Very Low Mine de-watering Duck River Catchment (Mella /Smithton Syncline GAA)* Unknown Alluvium over fractured to karstic Proterozoic dolostone No Groundwater extractions Unknown No No None to Very Low Agricultural irrigation Montagu River Catchment (Togari/Smithton Syncline GAA)* Unknown Alluvium over fractured Proterozoic sediments No Groundwater extractions Unknown No No None to Very Low Agricultural irrigation Welcome River Catchment (Smithton Syncline)* Unknown Alluvium over Cainozoic sediments and volcanics No Unknown Unknown No No None to Very Low Agricultural irrigation * areas were highlighted by stakeholders as potentially vulnerable to SWI, although there may be little to no SWI references/information available
Table 4 Summary of literature for areas identified as being vulnerable, or potentially vulnerable, to SWI in New South Wales. Location References Aquifer lithology SWI occurrence reported Driving factors Investigations SWI monitoring SWI management of assessment Land / groundwater use Hat Head (Ecoseal, 2011; Woolley et al., 2011) Quaternary sands No Groundwater extractions;, below average rainfall/droughts Water levels; salinity; water chemistry; SEAWAT (combines MODFLOW code with MT3DMS Yes (loggers installed July 2008) No Moderate Domestic Stuarts Point (DNR, 2006; Government NSW., 2004; O'Shea, 2005) Quaternary sands and alluvium associated with Macleay River Yes (DNR, 2006) Groundwater extractions; below average rainfall/droughts Limited hydrochemical and piezometer data No No Low Domestic Stockton (SKM, 2011; Wooley et al., 1995; Woolley et al., 2011) Quaternary sands No Groundwater extractions; average rainfall/droughts Water levels; salinity; water chemistry; 3D MODFLOW groundwater flow model; four 2D FEFLOW models No No Low Stock, domestic, mine & mineral processing, small-scale irrigation, industry Botany Sands, Sydney (Benker et al., 2007; Bish et al., 2000; Merrick and Knight, 1997; Timms et al., 2008) Quaternary sands Yes, 1960’s; shut down and usage moved inland (e.g. Timms et al., 2008) Groundwater extractions; below average rainfall/droughts Limited; No SWI specific studies No No None to Very Low Industry, chemical manufacturing, recreation Clarence River Floodplain (Johnston et al., 2005) Quaternary alluvium associated with Clarence River; estuarine deposits Yes, minor local Drains Limited hydrochemical and piezometer data No No None to Very Low Sugarcane
6 Summary of literature for areas identified as being vulnerable, or potentially vulnerable, to SWI in South Australia Location References Aquifer lithology SWI occurrence reported Driving factors Investigations SWI monitoring SWI management of assessment Land / groundwater use Adelaide Metropolitan (Gerges, 1996; Gerges, 2006; Gerges, 2000; Hodgkin, 2004; Jeuken, 2005; Lamontagne et al., 2005; Osei-Bonsu and Barnett, 2008; Zulfic et al., 2008) Tertiary aquifers comprising sandstones, limestone (minor sands) No Groundwater extractions; groundwater mining; urbanisation Water level; salinity; flownets; MODFLOW No No Moderate Urban, residential; parks and gardens; on occasions used to supplement Adelaide water supply Eyre Peninsula (Coffin Bay/Uley) (Alcoe, 2009; Auken et al., 2009; Brown and Harrington, 2003; Eyre Peninsula Natural Resources Management Board, 2006; Harrington and Brown, 2002; Harrington et al., 2006; Seidel, 2008; Zulfic et al., 2006) Quaternary karst limestone overlying Tertiary sands No in Uley South, Yes in Robinson’s Basin Groundwater extractions; below average rainfall/droughts Water level; salinity; CFCs; geophysical (AEM and surface); lumped parameter model for Uley South Basin Yes (but not SWI interface specific); infrequent No – exploring trigger level management Moderate Town supply; irrigation, industry Port MacDonnell (Barnett, 1976; King and Dodds, 2002; Stadter and Yan, 2000) Tertiary limestone No Groundwater extractions EM; limited salinity; numerical No No Moderate Irrigated agriculture; improved pasture; stock; domestic; industrial; groundwater dependant ecosystems Le Fevre Peninsula/ Adelaide (Lamontagne et al., 2005; Russell, 1996) Quaternary dune sands overlying Tertiary sands, sandstones, limestone Yes (e.g. (Gerges, 2006) Groundwater extractions; from underlying saline aquifer Water level; salinity; flownets; No No Low Residential; urban parks and gardens Herzberg,
Bunbury (Commander, 1981; Commander, 1982; Deeney, 1988) Cenozoic superficial sand sediments overlying multi-layered Jurassic sandstone aquifers separated by clay aquitards Yes, interface reported as extending up to 3 km inland Groundwater extractions; below average rainfall/droughts Water level, salinity monitoring, geophysical logging Yes No Low Urban and rural; irrigation Broome 2009c; Department of Water, 2008; Groundwater Consulting Services Pty Ltd., 2008; Laws, 1984; Laws, 1985; Laws, 1991; Water Authority of Western Australia, 1992a) Jurassic to Cretaceous Sandstone Yes (Laws, 1991; Water Authority of Western Australia, 1992a) Groundwater extractions; average rainfall/droughts Basic hydrogeological characterisation No No Low Town supply; horticulture; industry Derby (CSIRO, 2009c; Groundwater Consulting Services Pty Ltd, 2008; Laws and Smith, 1988; Smith, 1992; Water Authority of Western Australia, 1992c) Jurassic to Cretaceous Sandstone Yes (Groundwater Consulting Services Pty Ltd, 2008) Groundwater extractions hydrogeological characterisation No No Low Town supply; gardens; stock; domestic Cape (EPA, 1999; Lee, 2004; Martin, 1990; and Rivers Commission, 1999; Water Corporation, 1997) Tertiary karst limestone Yes (Lee, 2004) Groundwater extractions; below average rainfall/droughts Water levels; salinity: SUTRA No No Low Domestic; dependant aquatic cave fauna
Table 9 Summary of literature for areas identified as being vulnerable, or potentially vulnerable, to SWI in Queensland. Location References Aquifer lithology SWI occurrence reported Driving factors Investigations SWI monitoring SWI management of assessment Land/water use Burdekin River Delta (Arunakumaren et al., 2000; Fass et al., 2007; Lawrie et al., 2004; Lawrie et al., 2006; McMahon, 2004; McMahon et al., 2000; McMahon et al., 2002; McMahon et al., 2011; Narayan et al., 2007; NRMW, 2006; O'Shea, 1967; Qureshi et al., 2008; SKM, 2009; Wang et al., 2012; Werner, Quaternary alluvial delta Yes (ANRA, 2002; McMahon, 2004; NRMW, 2006) Groundwater extractions; average rainfall/droughts Water levels; salinity; theoretical inland extent of SWI using Ghyben-Herzberg; geophysical (resistivity and gamma); geomorphic and sedimentary facies analysis; hydrochemistry (major and minor ion; isotopes); 2D SUTRA; MODFLOW 2000 Yes Yes; artificial recharge; Lower Burdekin Groundwater Science Plan High Sugarcane; wetlands; adjacent Great Barrier Reef Pioneer Valley (Bedford, 1978; Carey et al., 2009; Cresswell, 2008b; Murphy et al., 2005a; Sundaram et al., 2001b; Werner, 2010b; Werner and Gallagher, 2006) Quaternary alluvium; in bedrock Yes (Bedford, 1978; Murphy et al., 2005a) Groundwater extractions; below average rainfall/droughts; flat topography; large tides (6 m in spring) and estuaries/tidal streams 16.5 km inland Water levels; salinity; hydrochemistry (major and minor ions; isotopes); mapping of 1000 µS/cm boundary between 1997 and 2000; 3D MODHMS; 2D SUTRA Yes Yes; rules based on trigger points for groundwater level and quality within the SWI area; pumping restricted where water levels drop below 1m AHD; cease pumping at 3000 µS/cm; artifical recharge explored High Sugarcane; industry (sugar mill) stock, residential domestic
National and state data review Data required An important component of the project is to review and collate the existing national and state baseline datasets that are of relevance to a national-scale vulnerability assessment of SWI. This can be and resource-intensive, as data requirements are comprehensive and need to be sourced from multiple agencies. Typical datasets and their sources have been provided in Table 10 as an initial starting point to investigate the datasets required for the project. After a comprehensive data review, much data appropriate for the project was found to be available. An outline of all datasets available and their sources follows in the subsections below, and is summarised in Appendix 1. Table 10 Typical datasets and sources. Hydrologic Climate (e.g. rainfall, evapotranspiration, Groundwater elevation Tidal information Groundwater quality (e.g. salinity and major ion chemistry) Groundwater recharge/discharge Groundwater extraction and sustainable yield information Climate databases Groundwater monitoring databases Coastal and climate databases Water quality databases Scientific literature, unpublished reports Unpublished reports and other publically available resources Hydrogeologic Bore survey (e.g. location, elevation, construction, intake screen depth, stratigraphic logs, aquifer extent and thickness) Aquifer properties (e.g. hydraulic conductivity, saturated aquifer thickness, porosity) Geology Geophysics (airborne radiometrics, magnetics, gravity, downhole conductivity and gamma logs, AEM) State agency groundwater databases Hydrogeological maps, scientific literature, unpublished reports Geological maps Reports, state agency databases Physiographic Geomorphology Soils Beach slope Topography/ bathymetry Surface water features Land use and infrastructure Vegetation maps (e.g. mangroves) Ecosystem maps Coastal geomorphic maps Soil maps Coastal mapping (OzCoasts) Topographic maps, Spot heights, DEM’s, LiDAR Drainage, streams and waterbody datasets Land use and topographic maps, remote sensing, agency databases, catchment authorities, unpublished reports Stage agencies, consultant reports Stage agencies, consultant reports
Table 14 Summary of key aquifer characteristics in different coastal depositional environments Depositional environment Dominant physical processes Coastline type Aquifer material Aquifer architecture Aquifer characteristics Examples Other Classic River Prograding Mud-rich with narrow sand bodies Narrow, radial sand bodies surrounded by muddy delta plain & lagoon deposits; some shore-parallel sand bodies Unconfined at surface but confined at depth; can contain multiple stacked aquifers Gilbert (QLD), King (TAS) Influenced by wave and tide energy Fan delta River Prograding Sand dominant, can contain gravel; minor mud units Radial channels; some shore-parallel units Unconfined to semi-confined; high connectivity; can contain multiple stacked aquifers Burdekin (QLD) Influenced by wave and tide energy estuary Wave Transgressive Barrier consists of well sorted medium to coarse topped by fine-grained sands Shore-parallel sand bar normal to estuarine funnel Unconfined aquifers associated with sand barrier (main) and tributary channels intervening beds form aquitards Port Sorell (TAS) Higher wave energy forms a lagoon & barrier system Coastal lagoon Wave Transgressive Well sorted medium to coarse sands topped by fine grained sands (barrier); fine-grained (lagoon) Sand barrier parallel to coast with lagoon trapped behind Unconfined aquifers associated with barrier complex (main) and sandy channels of lagoon (secondary) of River Murray (SA), Tomakin beach, Merimbula (NSW) Evolve into strandplain with sufficient sediment supply for coastal progradation Strandplain Wave Prograding Well sorted medium to coarse sands topped by fine-grained sands; underlain by marine sediments Large shore-parallel strands Unconfined but may be laterally compartmentalised by inter-strand fine-grained sediments; high permeability along length of strands and lower between strands; good permeability in underlying marine aquifer Massacre Inlet (QLD), Swan Coastal Plain (WA), Robbins Island (TAS)
flat/creek Wave Prograding Thin beds of silt, sand and mud; carbonate sediments Tidal channels oriented shore-normal and branching inland, forming a dendritic pattern Semi-confined where sand and mud are interbedded; thin and laterally extensive; high permeability basal marine sediments King Sound, Joseph Bonaparte Gulf (WA), Van Diemen Gulf, Victoria River (NT), Shark Bay (WA), Spencer Gulf, Gulf of St Vincent (SA), Corner Inlet (VIC) estuary Tidal Transgressive Sands at mouth; marginal sediments are fine muds & silts; sands & gravel along estuary axis Sand bars parallel to axis of estuarine funnel; dendritic tributary pattern Unconfined aquifers associated with the tidal channel (main) and tributary channel (secondary); intervening fine-grained sediments form aquitards; older aquifers may be semi-confined Ord River (WA) 15 Summary of key aquifer characteristics of coastal aquifers in older rocks and other settings Depositional environment Dominant physical processes Coastline type Aquifer material Aquifer architecture Aquifer characteristics Examples
sedimentary coasts Erosion Depositional or erosional Variable; can from fluvial to deeper marine deposits; dominated by sands to coarse silts, with fine silts and mudrocks acting as aquitards Sedimentary basin aquifers tend to be thick, hydraulically continuous over large areas, and contain multiple stacked aquifer systems that are confined May be highly structured with channelised sediments or laterally continuous and sheet-like Sydney Basin (NSW); Darwin area (NT); Perth Basin (WA) Basin margin sediments may be broken up by basement highs and locally deepened by the presence of incised palaeovalleys Karstic coasts Dissolution Erosional Limestone, dolomite or gypsum that has been affected by dissolution High anisotropic aquifer structures Confined or unconfined; characterised by sinkholes, caves and underground drainage; prone to clogging by fine grained deposits Cape (WA); Eyre Peninsula (SA) Patterns of dissolution and vary above/below watertable & with fresh/saline water Fractured bedrock Erosional Aquifers occur in fractures in fully lithified rocks (non-porous sedimentary, igneous or metamorphic) High anisotropic aquifer structures Variable characteristics as a function of rock type and fracture structure. The groundwater flow systems relate to climate and topography. aquifers tend to be unconfined.
Typically occur in elevated hinterlands thus hydraulic heads are often comparatively high. Southwest WA and eastern seaboard complex Varying compositions comprising several depositional environments Multiple and interconnected aquifers at a range of scales Varying characteristics Esperance (WA) Anthropogenic Human alteration through engineering works Sand, mud, crushed building materials) deposited on top of, or excavated into a sedimentary substrate Extensively modified by human activity, mostly by drainage or infill Deposits of strongly contrasting hydrological properties Hobart waterfront; Stanley wharf and esplanade (TAS)