RMA 2/11 Model
RMA Finite Element Model description
This proposal leverages a mature modeling system that is extensively calibrated and validated against all available velocity/flow and salinity data. The RMA 2/11 finite element model is a full-featured hydrodynamics/water quality modeling system of the full Bay-Delta estuary. The model is capable of solving the shallow water equations in one, two, or three dimensions. It includes the following features:
- Calibration and validation: The model has been extensively calibrated, validated and applied to CALFED funded studies including Suisun Marsh levee breaches [CALFED, 2001], Flooded Island Restoration Feasibility (Franks Tract) [CALFED, 2004], and Levee Risk Analysis [RMA, 2004]. The model was the subject of a two-day CALFED Science workshop expert panel that reviewed the models' fitness for levee breach modeling (June 2002). The DWR Suisun Marsh Branch is using the Suisun Marsh Pilot Study collected over three months of continuous velocity/flow data that to further improve RMA model calibration in the Marsh.
- Full Bay-Delta estuary modeling domain: Previous modeling analyses have shown that relatively small geometry changes (like levee breaches) can have hydrodynamics and scalar transport impacts on a large time and space scale [ref]. The RMA 2/11 models are calibrated and verified on a grid that includes the full Bay-Delta Estuary with downstream boundary at the Golden Gate, and upstream flow boundaries at the limit of tidal propagation (approximately Sacramento and Vernalis).
- Sediment transport estimation: Conceptual models of methyl mercury transport and fate suggest a useful correlation of MeHg with TSS concentration. The suspended sediment transport modules of the RMA model will be validated/calibrated against continuous TSS data collected in situ during three-month monitoring periods. We will develop a model of MeHg transport based on TSS transport and MeHg t ransformation process analysis to elucidate Suisun Marsh production and transport of MeHg to the Estuary.
- Wetting and drying boundary: Inter-tidal areas are "wetted and dried" twice each day by tidal action. The RMA 2/11 modeling system uses a "marsh element" approach to isolate finite elements from the grid when water levels approach the channel bottom. This is a key capability that a ssures proper tidal prism accounting especially in areas restored to tidal action through levee breaches.
- Geographical grid reference: Accurate computational "grids" can be constructed and modified based on geographically referenced ortho-quadrangles. All computational point within the models are automatically geo-referenced.
- Process analysis: RMA model output can be processed through a suite of filters to elucidate spatial residence time, Eulerian and Lagrangian tidal excursion, wave characteristics, tidal datum, and tidally averaged current and transport. Static and animation displays are seamlessly integrated. These features are essential for spatial and temporal integration and transport process understanding.