Effects of River Discharge and Tide Driven Sea Level Variation on Saltwater Intrusion in Sumjin River Estuary: An Application of Finite-Volume Coastal Ocean Model

Abstract

Shaha, D. C.; Cho, Y.-K., and Kim, T.-W., 2013. Effects of river discharge and tide driven sea level variation on saltwater intrusion in Sumjin River estuary: An application of finite-volume coastal ocean model. Salinity intrusion is one of the major problems in the Sumjin River Estuary (SRE). An unstructured-grid finite-volume coastal ocean model (FVCOM) was used to investigate the influence of different river discharges and tide driven sea level variation on salinity intrusion in the SRE. The variation of salt intrusion was predicted according to the variation of sea level driven by tide along the open boundary and the river discharge upstream. The model simulation results are in qualitative agreement with the available field data. The model provided a skilled reproduction of the observed temporal and spatial variability in salinity. The ebb flow is seaward from upstream to the mouth of the SRE. The river discharge is a dominant factor affecting salinity intrusion in this estuarine system during the wet season. A power law function has been established between the distance of salt intrusion and river discharge. The salt intrusion length responding to constant river discharges generally follows a power law of −0.14. In contrast, the salt intrusion length shows a better relationship with intratidal sea level variation at low river discharge. This model result allows us to predict salt intrusion in an estuary according to the variation of sea level and river discharge with climate change.