Physical modeling of inland freshwater lens formation and evolution in drylands

A visual approach to demonstrate groundwater flow processes

“…Therefore, simple visual displays in the laboratory can be very useful for showing how water and solutes move through porous media, how flow changes under different gradients, and what happens when physical and chemical changes are forced through access tubes at the surface. Sandtank set‐ups have long been recognized as an accepted method for elucidating key concepts in hydrogeology (Rau, Andersen, & Acworth, ; Rotz & Milewski, ; Silliman, Konikow, & Voss, ). Using this medium, the goal of this project was to develop a simple sandtank display to show industry (including energy producers, mining, and primary industry) representatives how the movement of heat and solutes can be monitored with in‐line sensors for a variety of environmental conditions and over long time scales.…”

Transient Evolution of Inland Freshwater Lenses: Comparison of Numerical and Physical Experiments

“…While saline groundwater systems in semi-arid and arid environments are generally considered a problem for water resource managers, the occurrence of shallow (<100 m) brackish to saline groundwater promotes the development of localized accumulations of subsurface freshwater referred to as inland freshwater lenses (IFLs) [1][2][3]. IFLs serve as alternative freshwater resources for drinking water, livestock management, and micro-oasis agriculture in several arid and semi-arid regions including the Middle East (e.g., Kuwait, Oman, United Arab Emirates (UAE), Saudi Arabia), Australia (e.g., Murray Basin, Queensland), Central South America (e.g., Paraguay), Central Asia (e.g., Turkmenistan), Africa (e.g., Zambia, Namibia), and elsewhere with similar environmental settings [2][3][4][5][6][7][8][9][10].…”

“…The resultant variable-density condition forms a boundary surface or freshwater-saltwater interface, above which a freshwater lens forms [15] (Figure 1). Unlike coastal and oceanic island freshwater lenses, which are stabilized by bounding seawater on [1].…”

“…Physical models [27], analytical solutions [23,24,28], and numerical models have demonstrated the relationships between recharge rate, hydraulic conductivity, differences in fluid densities, and coastal freshwater lens geometry. IFL investigations using geophysical techniques [5,7], analytical methods [8,14,29], and physical laboratory models [1] highlight IFL relationships between the physical and chemical properties (i.e., salinity, age) and geometry. However, none of these studies address the transient nature of IFLs over varying temporal and spatial scales.…”

“…Research into the geometry of IFLs is needed to adequately predict the position and sustainability of exploitable freshwater resources. The purpose of this research is to presents a variable-density, finite-difference numerical model that considers geometry (i.e., thickness, length) calibrated by and compared with shared results from physical model observations by Rotz and Milewski [1].…”