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

Abstract

Brackish to saline groundwater in arid environments encourages the development and sustainability of inland freshwater lenses (IFLs). While these freshwater resources supply much-needed drinking water throughout the Arabian Peninsula and other drylands, little is understood about their sustainability. This study presents a numerical model using the SEAWAT programming code (i.e., MODFLOW and the Modular Three-Dimensional Multispecies Transport Model (MT3DMS)) to simulate IFL transient evolution. The numerical model is based on a physical laboratory model and calibrated using results from simulations conducted in a previous study of the Raudhatain IFL in northern Kuwait. Data from three previously conducted physical model simulations were evaluated against the corresponding numerical model simulations. The hydraulic conductivities in the horizontal and vertical directions were successfully optimized to minimize the objective function of the numerical model simulations. The numerical model matched observed IFL water levels at four locations through time, as well as IFL thicknesses and lengths (R2 = 0.89, 0.94, 0.85). Predicted lens degradation times corresponded to the observed lenses, which demonstrated the utility of numerical models and physical models to assess IFL geometry and position. Improved understanding of IFL dynamics provides water-resource exploration and development opportunities in drylands throughout the Arabian Peninsula and elsewhere with similar environmental settings.

Effects of River Partial Penetration on the Occurrence of Riparian Freshwater Lenses: Experimental Investigation

“…Laboratory‐scale physical models, similar to those proposed for the current study, are commonly employed to investigate variable‐density flow phenomena, which are often challenging to characterize under field conditions. Examples include laboratory sand‐tank experiments of riparian lenses (Werner et al., 2016; Wu et al., 2020), inland freshwater lenses (Rotz & Milewski, 2019; Rotz et al., 2020), lenses within oceanic islands (Lu et al., 2019; Stoeckl et al., 2016), saltwater upconing (Werner et al., 2009), and seawater intrusion (Badaruddin et al., 2015; Mehdizadeh et al., 2014). In addition, physical models can be used to develop useful benchmarks for model testing (Dose et al., 2014), which is particularly important for models that incorporate buoyancy and/or dispersive processes given the complex flow patterns that often arise from the combination of these factors.…”

The Zonality of Underground Water Supply Sources for Pastures in the West Kazakhstan Region

“…Such lenses serve as alternative sources of freshwater for drinking, animal husbandry, and micro-oasis agriculture in several arid and semiarid regions. Small freshwater lenses in these areas are sufficient for a short period [Rotz, 2020]. In low-water and waterless territories, one of the ways to supply animals with water is to collect meltwater and rainwater from the surrounding area [Moritz et al, 2013].…”