TRIM/UnTRIM

Criterion

Explanation

General Description

TRIM and UnTRIM models are a series of numerical models developed by Prof. Vincenzo Casulli of Trento University. 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 called UnTRIM which preserves the same basic numerical properties and modeling philosophy, only the computations are carried out over an unstructured orthogonal grid.

Model Domain

The UnTRIM Bay–Delta model was the first 3-D model applied to the Bay–Delta system that spanned the entire estuary from the Pacific Ocean through the Sacramento River and the San Joaquin River.

Developer

Prof. Vincenzo Casulli of Trento University, Italy

Hardware computing requirements

None specified.

Code language

FORTRAN

Original application

San Francisco Bay

Public/proprietary and cost

The model is proprietary and not available to the public.

Physically or empirically based

Physically based

Mathematical methods used

TRIM is a semi-implicit finite difference (volume) model based on the three-dimensional shallow water equations as well as on the three-dimensional transport equation for salt, heat, dissolved matter and suspended sediments. unTRIM is the unstructured grid version of TRIM.

Input data requirements

The TRIM/unTRIM model is well parameterized for the Bay-Delta. Input data includes:

• Domain (grid parameters, bathymetry)
• Initial conditions (water level, salinity, water temperature, pollutant and sediment concentrations)
• Boundary conditions (inflows, outflows, water level, salinity, water temperature, pollutant and sediment concentrations)
• Physical parameters (describing constants, viscosity, heat flux, sediment, tidal forces)
• Environmental parameters (precipitation, evaporation, wind speed and direction)

Outputs

Model output includes water level elevation at the free surface, current velocity, tracer concentration (e.g. salinity, temperature, suspended sediments), hydrodynamic pressure.

Pre-processing and post-processing tools

Unknown.

Representation of uncertainty

Uncertainty analysis is not integrated into the modeling framework.

Prevalence

There are many applications of unTRIM to the Bay-Delta in the peer reviewed literature. Other hydrodynamic models, such as RMA 3D, are based on the unTRIM computational engine.

Ease of use for public entities

Because the model is proprietary and not available to the public, it can only be used by the model developers and their consultants.

Ease of obtaining information and availability of technical support

The model is not supported for public use.

Source code availability

The model is proprietary.

Status of model development

Challenges in integration

Because the model is proprietary and not available to the public, it can only be used by the model developers and their consultants.