Title: Reconstruction of Spatially Continuous Water Levels in the Columbia River Estuary: The Method of Empirical Orthogonal Function Revisited

Journal: Estuarine, Coastal and Shelf Science, 22: 81-90.

Authors: PAN H. -D., and X. -Q. Lv*

Abstract: Accurate water level measurements in tidal rivers are vital and essential for water resources management, coastal engineering and hydrodynamic research. However, the number of tide gauging stations in tidal rivers is far from adequate. In this paper, we revisit the method of Empirical Orthogonal Function (EOF) which is widely used in geophysics for spatial-temporal data. Different from previous studies which used EOF as a data analysis method, here, EOF is used as a data interpolation method to reconstruct spatially continuous water levels in the fluvial estuary. The EOF interpolation (EOFI) decomposes spatial-temporal water levels into spatial patterns and temporal patterns, and then, EOFI spatially integrates tidal heights using the interpolated spatial patterns between the stations. EOFI is simple to understand and easy to implement while its results are highly accurate. Moreover, different from numerical modeling which needs the bathymetry, river shorelines, and river flow data, EOFI only needs the water level data. In summary, although EOFI has some limitations, it has the potential to be widely used in reconstructing water levels and other spatial-temporal parameters.