A Note on Conservative Mixing: Implications for Selecting Salinity-Transport Model Constituents in the San Francisco Estuary

The deviation of specific electrical conductance (EC) from conservative mixing behavior is well-established in the scientific literature. This principle based on observation that, as salt concentration a water sample increases, mobility individual ions decreases, and thus their ability to conduct electricity decreases. Despite this fact, some commonly used models for salinity transport San Francisco Estuary (estuary) utilize EC primary simulation constituent, treating it quantity. Such modeling approach has likely been followed exploit wide availability data model calibration validation, obviate need translate between domain characterized by multiple source waters with varying ionic make-ups. Arguably, provides reasonable trade-off translation error error. In paper, we critically evaluate approach, employing an extensive set that includes measurements major ion concentrations estuary. We demonstrate quantify steady-state, behavior; review three bulk measures (practical salinity, strength, limiting equivalent conductance); source-dependent correlations find conductance—a value assumes uninhibited among sample—to be attractive alternative addition being quantity, consistently correlated estuary’s dominant waters, addresses concerns related data-translation conclude paper discussing pros cons adopting various salinity-transport constituents.