title: Modeling Coastal Salinity in Quasi 2D and 3D Using a DUALEM-421 and Inversion Software.
abstract: Rising sea levels, owing to climate change, are a threat to fresh water coastal aquifers. This is because saline intrusions are caused by increases and intensification of medium-large scale influences including sea level rise, wave climate, tidal cycles, and shifts in beach morphology. Methods are therefore required to understand the dynamics of these interactions. While traditional borehole and galvanic contact resistivity (GCR) techniques have been successful they are time-consuming. Alternatively, frequency-domain electromagnetic (FEM) induction is potentially useful as physical contact with the ground is not required. A DUALEM-421 and EM4Soil inversion software package are used to develop a quasi two- (2D) and quasi three-dimensional (3D) electromagnetic conductivity images (EMCI) across Long Reef Beach located north of Sydney Harbour, New South Wales, Australia. The quasi 2D models discern: the dry sand (<10 mS/m) associated with the incipient dune; sand with fresh water (10 to 20 mS/m); mixing of fresh and saline water (20 to 500 mS/m), and; saline sand of varying moisture (more than 500 mS/m). The quasi 3D EMCIs generated for low and high tides suggest that daily tidal cycles do not have a significant effect on local groundwater salinity. Instead, the saline intrusion is most likely influenced by medium-large scale drivers including local wave climate and morphology along this wave-dominated beach. Further research is required to elucidate the influence of spring-neap tidal cycles, contrasting beach morphological states and sea level rise.
authors: School of Biological, Earth and Environmental Science, The University of New South Wales, Sydney, NSW 2052, Australia.
authors: Gareth
authors: G
authors: Davies
authors: Jingyi
authors: J
authors: Huang
authors: Fernando Acacio
authors: FA
authors: Monteiro Santos
authors: John
authors: J
authors: Triantafilis
mesh_terms: D003198:Computer Simulation; D055590:Electromagnetic Phenomena; D004784:Environmental Monitoring / Q000379:methods*; D005618:Fresh Water; D060587:Groundwater / Q000737:chemistry*; D009517:New South Wales; D054712:Salinity; D012623:Seawater; D012984:Software; D055871:Tidal Waves