IMPACTS OF DENSITY-DRIVEN FLUCTUATIONS ON GROUNDWATER CAUSED BY SALTWATER INTRUSION

Abstract

Engineering knowledge on soil and water is crucial for sustainable water resources management.
Saltwater intrusion due to such as storm surges or high tide, often causes damage to crops or farmlands. Salt is
leached by freshwater to prevent losses; however, this activity might create a density-driven flow of salinity into
the groundwater, and finally cause saltwater to spread widely downstream. This study analyzed the impact of
saltwater intrusion on groundwater flow through laboratory experiments. The oscillatory phenomena of vertically
intruding saltwater into horizontally flowing groundwater were investigated. To determine the qualitative
differences of saltwater intrusion under various conditions, a laboratory-scale aquifer flow model was set up. An
oscillatory flow was estimated through the proposed Rayleigh number, obtained for factors such as different
saltwater concentrations, basal groundwater flow rate and so on. The photography results indicated that oscillatory
flow occurred, the variation of which could be evaluated by the Rayleigh number. Furthermore, an increase of the
basal groundwater flow rate tends to reduce the negative effects of salinity intrusion.