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.