Investigation of Solute Transport Phenomena in Subsurface Dam Reservoir by Model Experiments

Abstract

Solute transport phenomena in subsurface dam reservoirs are affected by cut-off walls, the hydraulic conductivity of the aquifer, and saltwater intrusion. This study conducted solute transport experiments on four types of model aquifers with different hydraulic conductivity distributions. Solute transport behavior was then quantified using image analysis. As a result of quantifying the solute transport routes against both the storage and saltwater obstruction dams and evaluating the refraction of solute transport route crossing the boundaries of layers with different hydraulic conductivity based on centroid locations of solutes, it was revealed that the ratio of the hydraulic conductivity corresponds to the refractive angle of solute transport route. Calculating the spread of solute as the spread of a concentration distribution led to a conclusion that the spread of concentration distribution of solute close to the groundwater table increased with the transport distance regardless of the presence or absence of saltwater wedges. Meanwhile, the spread in horizontal direction of solute in the deep aquifer was limited due to the effect of a cut-off wall. In addition, it was revealed that entropy can be used as the indicator of spread of concentration distribution during short transport distances.