California Water and Environmental Models and Data

Model category descriptions from "Central Valley Project Improvement Act Programmatic Environmental Impact Statement, Phase II, Analytical Tools Report", April 1, 1994, USBR.

Reservoir Operations/Stream Flow: For this inventory, surface water analytical tools are defined as tools that can simulate reservoir operations, stream flows, surface water diversion, and canal flows.


Water Balance: Water balance analytical tools are tools that simulate mass balance of the hydrologic system. These tools are reviewed under Groundwater.


Groundwater: Groundwater analytical tools are defined as tools that can simulate groundwater conditions, such as groundwater levels, subsidence, recharge, and groundwater quality.


Hydrodynamic/Transport: Hydrodynamic and Transport tools are defined as tools that can simulate the flow and quality of water in a river, delta, or bay environment and may include such factors as tidal influences. The focus is the Sacramento-San Joaquin Delta.


Water Temperature: Water temperature tools are defined as tools that can simulate the temperature of water in a reservoir, river, or estuarine environment.


Water Quality: Water quality tools are defined as tools that can simulate the quality of surface or drainage waters.


Power: Power tools are defined as tools that can either simulate power generation from hydropower facilities or the power demand for pumping facilities and other demands.


Economics: Regional economics tools are defined as tools that can assess impacts on total economic activity, personal income, and employment from changes in agricultural production, water availability changes or other changes.  Agricultural production economics tools provide assessment of changes in crop and income production due to policy changes or water price changes. Specific impacts assessed may include cropping pattern changes, land fallowing, or water purchases.  Municipal and Industrial (M&I) economic tools are used to assess the value of changes in water supply to urban areas that may result from implementation of the CVPIA. This includes changes to existing CVP M&I contractors and to potential purchasers of transferred water.  Recreation economics tools are defined as tools that assess impacts on the various types of recreation, including stream and river recreation, reservoir recreation, delta recreation, and ocean recreation. Fisheries economics tools are defined as tools that assess impacts on various types of sport and commercial fishing activities.


Vegetation and Wildlife: Habitat wildlife and vegetation tools provide evaluation of quality changes that may be influenced by changes in water availability or quality.


Fisheries: Fisheries population tools simulate the survival of certain species based on water flow, temperature, or other factors.


San Joaquin River Fall-Run Chinook Salmon Population Model

Report, California DFG, November 2005 (.pdf, 0.8 MB)

Model, California DFG, November 2005 (.xls,  7.1 MB)

            For more information regarding this model, please contact Dean Marston at


FDM-Based Models

The first group includes the Fischer Delta Model (FDM) and the DWR-DSM model. Both of these models are based on similar numerical schemes; they are externally coupled models of flow and salt transport.

Fischer Delta Model. The Fischer Delta Model (FDM) is a deterministic hydrodynamic and salt transport model developed for the Sacramento-San Joaquin Delta. This model simulates flow and salinity variations due to changes in channel geometry, hydrologic variability, and operation of control structures in an estuarial environment.

The FDM simulates hydrodynamics by solving the one-dimensional flow equation by the method of characteristics. The convective dispersive transport equations are solved by a Lagrangian method. Flow and water quality are simulated in a sequential manner; tidally averaged velocities computed by the flow module are stored for each time step and are used as input to the salinity model. The flow domain is discretized into a number of smaller channel segments (called links), which are joined by common points (called junctions).

There are several versions of the FDM, with each version developed to meet special needs of different projects. The model area covered is also different in each version. Version 7.0 includes Sacramento River downstream of the City of Sacramento, San Joaquin river downstream of Vernalis, and Sacramento-San Joaquin Delta east of Benicia Bridge to Eckley (in the Carquinez Strait). Versions 8.0 and higher do not require input of the downstream boundary salinity, instead it is calculated. This effectively extends the boundary to the Golden Gate. Version 9.0, used by Contra Costa Water District (CCWD), has incorporated improved numerical methods to eliminate numerical dispersion. A consulting firm, Flow Science, is currently working on Version 10.0, which will revise the channel geometries of the original model to incorporate information from new field surveys. DWR-DSM. The Department of Water Resources Delta Simulation Model (DWR-DSM) is a deterministic hydrodynamic and salt transport model developed by the California Department of Water Resources (DWR) for Sacramento-San Joaquin Delta. This model is an improved version of the FDM with the following revisions: (1) a spatially finer description of the Delta geometry; (2) additional simulation capabilities of hydraulic structure operation; (3) detailed accounting for agricultural diversions and return flows; (4) correction for leak-plug algorithm of FDM; and (5) procedures for modeling gate operation, hourly variable pumping, and earth tides. The model area in the Delta includes Sacramento river downstream of the City of Sacramento, San Joaquin river downstream of Vernalis, and Sacramento-San Joaquin Delta east of the Benicia Bridge.

The DWR-DSM consists of (1) a flow module DWRFLO, which computes stage, velocity, and flow circulation, and (2) a transport module DWRSAL. These two modules are not coupled, but are sequentially linked, as in the FDM. The Sacramento-San Joaquin Delta is currently represented in DWR-DSM as a network of 500 interconnected channels, 420 junctions, 13 open water areas, and approximately 20 tide gates.


DSM2 is a publicly available one-dimensional hydrodynamic, water quality, and particle-tracking model. DSM2 can calculate stages, flows, velocities; many mass transport processes, including salts, multiple non-conservative constituents, temperature, THM formation potential and individual particles. The model has primarily been used in the Sacramento-San Joaquin Delta but has currently been extended to the upper San Joaquin River and the California Aqueduct and Delta Mendota Canal.


More information about DSM2 including documentation, program executable, user group and calibration can be found at

RMA-Based Models

The RMA-based models include the Link-Node Model and the RMA Multidimensional Models. These models are coupled flow and salt transport models.

Link-Node Model. The Link-Node model is a one-dimensional hydrodynamic model developed by Resource Management Associates (RMA) for the San Francisco Bay-Delta system. This model also has several versions. The Delta version of the model includes Sacramento River downstream of the City of Sacramento, San Joaquin River downstream of Vernalis, and Sacramento-San Joaquin Delta east of the Benicia Bridge. Other versions of the model extend the boundary to include San Francisco Bay and areas within Golden Gate Bridge.

Two water quality modules are linked to RMA Link Node model: (1) AQUAL, which considers tidally averaged transport velocities to determine long-term trends in water quality; and (2) DQUAL, which considers diurnal variations in tidal hydrodynamics to simulate diurnal fluctuations in water quality. The flow domain is discretized into channel links connected by nodes; one node may be connected to several nodes, resulting in pseudo-two-dimensional description of open water areas. The one-dimensional equation of motion is written for the links and the continuity equation is applied at the nodes. Recent software additions include animation capability and an improved solution scheme. The new Eulerian-Lagrangian algorithm allows the coupling of flow and salt transport solution within each time step.

RMA Multidimensional Models. RMA developed a two-multidimensional model for estuarine hydrodynamics and salt transport. Dr. Ian King of University of California, Davis, maintains the models. The Resource Management Associates (2)-Dimensional Vertically averaged hydrodynamic model (RMA-2V) was originally developed for the U.S. Army Corps of Engineers (COE). This model forms the main hydrodynamic components of the "TABS-2" system used by the COE and U.S. Environmental Protection Agency (EPA). Nonlinear two-dimensional vertically averaged shallow flow equations are solved by the finite element method. Phenomenological terms include wind stress, Coriollis effect, and bottom stress. The model assumes constant density, so that baroclinic effects are not considered. Recent modifications of the RMA-2V model include the option to transition from one-dimensional to two-dimensional elements, and an improved algorithm for handling wetting and drying shallow areas along the margins of the estuary.

RMA-2V is linked with two-dimensional water quality model Resource Management Associates Version 4 Model (RMA-4). RMA-4 is an advection-diffusion model that simulates simple conservative constituents, and constituents that follow first order growth and decay kinetics.

Resource Management Associates Version 10 Model (RMA-10) is a multidimensional finite element model for simulating estuary hydrodynamics that allows for three-dimensional formulation of the flow domain. The model solves three dimensional shallow water equations, including baroclinic effects. The system of equations includes the horizontal momentum equations in two directions, the vertically integrated continuity equation, the salinity transport equation, and an equation of state. The model is used by COE as the national Standard Estuary model.

Semi-Implicit-3D Model (SI-3D) is a three-dimensional numerical model developed by Dr. Peter E. Smith at U.S. Geological Survey in the 1990s to simulate the density-driven gravitational circulation in the deepwater channels of the San Francisco Bay and, more recently, the Sacramento River in the vicinity of the Delta Cross Channel. The model uses a three-time-level, leapfrog-trapezoidal numerical scheme that is second-order accurate in the spatial and temporal numerical approximations. The three-time-level scheme is preferred over a two-time-level scheme for problems with strong nonlinearities. The stability of the semi-implicit scheme is free from any time-step limitation related to the terms describing vertical diffusion and the propagation of the surface gravity waves. A key feature of the scheme is that it does not rely on any form of vertical/horizontal mode splitting to treat the vertical diffusion implicitly. The model is programmed in Fortran 95 and is designed for parallel processing on shared memory computers. A Java-based, 3-D particle-tracking model and interactive visualization toolkit are available for use with the model.

TRIM and UnTRIM models are a series of numerical models developed by Prof. Vincenzo Casulli of Trento University. A characteristic analysis of the shallow water equations points out that the numerical instability is controlled by the gravity wave terms in the momentum equations and by the transport terms in the continuity equation. A semi-implicit finite-difference scheme has been formulated so that these terms and the vertical diffusion terms are treated implicitly and the remaining terms explicitly to control the numerical stability and the computations are carried out over a uniform finite-difference computational mesh without invoking horizontal or vertical coordinate transformations. TRIM stands for Tidal, Residual, Intertidal Mudflat Model, which was named in the paper by Cheng, Casulli, and Gartner, 1993. Further implementations and applications of TRIM models in studies of the San Francisco Bay and the Delta took place at the U. S. Geological Survey and at Stanford University. An unstructured grid version of TRIM model family is introduced, or UnTRIM (pronounces as “you trim”), which preserves these basic numerical properties and modeling philosophy, only the computations are carried out over an unstructured orthogonal grid. The unstructured grid offers the flexibilities in representing complex study areas so that fine grid resolution can be placed in regions of interest, and coarse grids are used to cover the remaining domain. Thus, the computational efforts are concentrated in areas of importance, and an overall computational saving can be achieved because the total number of grid-points is dramatically reduced. To use this modeling approach, an unstructured grid mesh must be generated to properly reflect the properties of the domain of the investigation. The new modeling flexibility in grid structure is accompanied by new challenges associated with issues of grid generation. To take full advantage of this new model flexibility, the model grid generation should be guided by insights into the physics of the problems; and the insights needed may require a higher degree of modeling skill. Please refer to the web page for detailed information.

Cheng, R. T., V. Casulli, and J. W. Gartner, 1993, Tidal, residual, intertidal mudflat (TRIM) model and its applications to San Francisco Bay, California, Estuarine, Coastal, and Shelf Science, Vol. 36, p. 235-280.