The support for this project was provided in part by a Miller Foundation grant to the Institute of Sustainability and Systems at Portland State University and a Portland State Research enhancement grant. D.A. Jay and S.A. Talke were supported in part by the National Science Foundation (NSF) grant: Secular Changes in Pacific Tides, OCE-0929055. S.A. Talke was supported in part by two additional NSF grants: 19th Century US West Coast Sea Level and Tidal Properties, OCE-1155610 and Career: Modeling 19th-century estuaries to address 21st century problems, award 1455350.
Journal of Geophysical Research: Oceans
Tidal currents -- Flow estimation -- Mathematical models, Oceanography -- Columbia River Estuary (Or. and Wash.) -- Mathematical models, Columbia River Estuary (Or. and Wash.)
Reliable estimation of freshwater inflow to the ocean from large tidal rivers is vital for water resources management and climate analyses. Discharge gauging stations are typically located beyond the tidal intrusion reach, such that inputs and losses occurring closer to the ocean are not included. Here, we develop a method of estimating river discharge using multiple gauges and time-dependent tidal statistics determined via wavelet analysis. The Multiple-gauge Tidal Discharge Estimate (MTDE) method is developed using data from the Columbia River and Fraser River estuaries and calibrated against river discharge. Next, we evaluate the general applicability of MTDE by testing an idealized two-dimensional numerical model, with a convergent cross-sectional profile, for eighty-one cases in which nondimensional numbers for friction, river flow, and convergence length scale are varied. The simulations suggest that MTDE is applicable to a variety of tidal systems. Model results and data analyses together suggest that MTDE works best with at least three gauges: a reference station near the river mouth, and two upstream gauges that respond strongly to distinct portions of the observed range of flow. The balance between tidal damping and amplifying factors determines the favorable location of the gauges. Compared to previous studies, the MTDE method improves the time resolution of estimates (from 2.5 to < 1 week) and is applicable to systems with mixed diurnal/semidiurnal tides. However, model results suggest that tide-induced residual flows such as the Stokes drift may still affect the accuracy of MTDE at seaward locations during periods of low river discharge.
Moftakhari, H. R., D. A. Jay, and S. A. Talke (2016), Estimating river discharge using multiple-tide gauges distributed along a channel, J. Geophys. Res. Oceans, 121, 2078–2097.