Modeling and predicting intertidal variations of the salinity field in the Bay/Delta

San Francisco Bay and the Sacramento/San Joaquin Delta have challenged estuarine modelers for some years.  Accurate, broad-scale models of this estuary have been in demand by those concerned with its ecological health and the development of sound management policies.  A description and better understanding of the dynamics that govern the bay/delta are complicated by the system's complexity, requiring models that are sophisticated enough to capture the subtle physical processes involved.

One approach to simulating daily to monthly variability in the bay is the development of intertidal model using tidally-averaged equations and a time step on the order of the day.  An intertidal numerical model of the bay's physics, capable of portraying seasonal and inter-annual variability, would have several uses.  Observations are limited in time and space, so simulation could help fill the gaps.  Also, the ability to simulate multi-year episodes (eg, an extended drought) could provide insight into the response of the ecosystem to such events.  Finally, such a model could be used in a forecast mode wherein predicted delta flow is used as model input, and predicted salinity distribution is output with estimates days and months in advance.  This note briefly introduces such a tidally-averaged model (Uncles and Peterson, in press) and a corresponding predictive scheme for baywide forecasting.