Astronomical Tide and Storm Surge Signals Observed in an Isolated Inland Maar Lake Near the Coast

Aimed at the explanation of clear tidal signal and storm surge signals in a closed inland lake near coast (the Huguangyan Lake), this work uses combined approach with observations model experiments. Lake is freshwater coneless volcanic crater tropical southern China, less than 5 km from an estuary. It has diameter about 1.5 relatively deep water up to 20 m. Bottom pressure was measured acoustic Doppler current profiler (ADCP) for 10 days September 2018 January 2019. The encompass period Typhoon Mangkhut, which passed region when it made its landfall. time series demonstrate subtidal signals. remains even if we exclude barometric effect. Interestingly, no surface connection ocean. astronomical tide amplitude 2 cm. major include principal solar semidiurnal (S2) lunisolar (K1) constituents. During passage level variability inside increased by order magnitude (>0.3 m). To examine whether change due natural oscillations (or seiche), numerical wind-driven hydrodynamics designed using 3-D Finite Volume Community Ocean Model (FVCOM). results show that small first-order seiche can be generated, but only scale minutes much smaller observed elevation changes. This excludes any measurable cannot wind-driven. Moreover, tides are not generated potential, as too having locally tide. main result our study therefore excluded local tidal-generating force, seiche, effect, possible causes oscillation variation least one greater caused weather-induced overall coastal ocean transmitted into through groundwater connection. All these lead conclusion connected groundwater.