Numerical gauge approach to water-level datum determination

In the United States, water-level datums are computed by applying National Ocean Service algorithms to records obtained at fixed gauges. These physical gauges are expensive to install and maintain, and they suffer certain practical limitations such as requiring a storm-resistant platform and convenient access. As a supplement to physical gauges, in this paper a modeling approach is explored whereby physical gauges at boundaries drive a calibrated numerical model from which the calculated time series of water level at any internal grid point may be considered as a "numerical" gauge. A proof-of-concept study for the upper Laguna Madre, Texas, is described that compares monthly and annual tidal datums and range determined from a co-located numerical gauge and physical gauge. The favorable comparison indicates the viability of the numerical gauge concept.