Experiences of construction of an experimental setup for saltwater intrusion around coastal aquifers

Aquifers, as the primary source of freshwater in coastal zones, are always threatened by saltwater intrusion, so assessment of groundwater behavior in response to the seawater has ever been of interest to researchers. Employing physical-laboratory models is one of the conventional methods in the study of groundwater dynamics in contact to saltwater. In this paper, the experiences of setting up a laboratory model of seawater intrusion issues are presented in detail. The model is 118 cm long, 12 cm wide and 60 cm high and uniform Glass beads are used as the porous medium in two different grain sizes. In this research, the challenges of construction, keeping the head and salinity constant in the side and main tanks as well as estimation of seepage flow rate have been studied. Results showed that the tests performed in coarse-grained medium reached a steady state in a shorter time than fine-grained one, with more accuracy which led to less salinity variation during the test. Furthermore, the conducted analysis on the dyes used as tracers of saltwater revealed that the amount of absorption of a dye seems independent from the grain size. Among all employed chemical and food dyes, Sunset-Yellow showed a very good match with saltwater movement in the medium. The findings of current research present a useful guideline for carrying relevant experiments out as well design of a successful setup.