Experimental study of inorganic solute transport under different hydraulic gradients and various groundwater stresses

Abstract

Abstract In this study, a laboratory-scale model representing a phreatic aquifer with a horizontal base was designed to examine the effects of horizontal hydraulic gradient, artificial recharge, and groundwater pumping on solute transport processes aquifers. Three different scenarios included injection of sodium chloride solution, artificial recharge with fresh water, and groundwater pumping, were examined in a sand tank. One hundred eight samples for nine tracers (sodium chloride) experiments were collected from two different monitoring well’s depths. The measured concentrations were plotted against time (180 min) for each experiment. The results showed that through a higher horizontal hydraulic gradient, sodium chloride movement was enhanced, specifically in the same direction in which groundwater flows. When a constant artificial recharge was applied, the sodium chloride plume spread, and the solute concentration was decreased. Moreover, groundwater pumping speeds up the movement of sodium chloride plume in the direction of the pumping well. Such impacts of groundwater pumping and artificial recharge can be noticed more prominently when a higher hydraulic gradient is applied.