4 Types of Density for Groundwater Flow

Groundwater density varies significantly with salinity and temperature as was shown in Figure 3 of Section 2. Where this is the case, there is the potential for variable-density flow to exist in many groundwater systems. Apart from coastal groundwater systems, which were mentioned in Section 1, density-driven flow can also be important in groundwater systems impacted by man, such as radioactive waste disposal sites (NEA, 1992), aquifer thermal energy storage systems (van Lopik et al., 2016), managed aquifer recharge schemes (Missimer et al., 2002; Ward et al., 2007), and finally waste disposal or contaminated sites (Zhang and Schwartz, 1995) where the contaminant plume is denser than the surrounding groundwater. Density-driven flow is also important on geological timescales in determining the development of ore deposits (Garcia-Fresca et al., 2012; Garven et al., 2003; Raffensperger and Garven, 1995), geochemical alteration of carbonate platforms (Garcia-Fresca et al., 2012; Jones et al., 2004; Wilson et al., 2001) and freshening and salinization of continental shelves due to global sea-level changes (Kooi et al., 2000a; Person et al., 2003). During the last decade or two, density-driven flow has also been studied extensively for the sequestration of carbon dioxide in subsurface reservoirs (Riaz et al., 2006; Ringrose et al., 2021).