Periodic forcing of surface water-groundwater interaction: modelling in vertical section

摘要: Sinusoidal variations in recharge can induce cyclical flows surface water and groundwater. In this thesis, such time-dependent are explored a coupled lakeaquifer system. The modelling extends previous steady state results introduces new flow-visualisation techniques. Local responses 2D vertical section illustrated for lakes within 1D regional groundwater mound. theory employs complex variables to decouple the periodic into separate fluctuating components. The time dependent behaviour causes lake-aquifer flow change between flowthrough, discharge regimes. Corresponding fluctuations inflow outflow across lakebed allow interchange of lake with aquifer (recycling recapture). This also gives rise sinuous flowpaths that result apparent dispersion; number size waves, cusps loops is characterised by nondimensional waviness ratio. Streakline plots introduced provide an intuitive impression motion. Such enhanced animation illustrate potentially dispersive nature flows. Interplay determines type strength regime transition. Importantly, there inverse relationship head response. dimensionless response time; function geometry, hydraulic properties period fluctuation. During fast response, propagates mainly as fluctuation flow, small phase lags; particle trajectories form elliptical paths visualised flows. With slower variation manifest mostly level; perturbations nearly state. position setting, lake, ratio important Flow-through regimes occur throughout but dominate when lower system greater. Discharge higher system, large magnitude.