Abstract

This study characterizes the hydrodynamics of the Dalcahue and Yal channels, key aquaculture areas within the Chiloé Inland Sea (CIS). It demonstrates the significant influence of bathymetric constrictions on local circulation patterns, tidal modulation, and biogeochemical variability. Dalcahue exhibits distinct bidirectional residual flows, characterized by intensified central inflows (NW-NE) and reinforced outflows (SE-SW) along the Quinchao coast, driven by channel curvature and bathymetry, with velocities reaching up to 70 cm/s in constrictions. In contrast, Yal shows a weak surface residual layer and persistent northwestward mid-depth flow, indicative of vertical tidal energy variations. Semidiurnal tidal forcing (M2, S2) predominantly drives current variability, explaining 50–75 % of observed fluctuations. A significant presence of the M4 overtide (up to 33 % in C2) highlights non-linear tidal interactions, crucial for understanding tidal asymmetry and net material transport. Weak correlations between sea level and dissolved oxygen suggest that strong tidal currents and mixing in constrictions counteract stratification, ventilating deeper layers. These findings enhance our understanding of physical oceanography in the context of the CIS, providing vital insights for environmental management and aquaculture planning by highlighting the role of constriction-induced hydrodynamics in estuarine systems worldwide. © 2025 Elsevier Ltd