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Track: Water Resources
Chuching Wang
Metropolitan Water District of Southern California
350 S Grand Ave
Los Angeles, CA 90071
Telephone: 213-217-6188
Fax: 213-217-6949
E-mail: cwang@mwd.dst.ca.us
Kevin Reagan
Application of GIS on Bay-Delta Hydrodynamic and Salinity Modeling
Defining Issue: California's Bay-Delta estuary is an important habitat for many fish and wildlife species. It is also critical to California's economy, supplying drinking water for 20 million Californians and irrigation water for 200 crops including 45 per cent of the nation's production. The Bay-Delta ecosystem is in a declining state due to decades of competing or conflicting interest on water among various stakeholders. CALFED, a federal and State agency Consortium, in collaboration with stakeholders is currently in an effort to identify the long-term solutions to ensure reliable water supplies and a healthy ecosystem in the Bay-Delta. Metropolitan Water District of Southern California (MWD) has been developing and applying a delta simulation model (DSM) to evaluate the potential short-term and long-term hydrodynamic and salinity impacts due to potential CALFED solution alternatives. The model is a one-dimensional link and node configuration representing the complex network of waterways in the Bay-Delta.
Operation of the model is resources intensive. It requires long CPU hours to run. It requires a lot of input data. It also produces 800 MB worth of information (time series of various parameters for every link and node of the model) for every single year real tides run. How to digest that output information in a timely and efficient manner and how to present the information in a compact and effective way so they can be incorporated in the decision making process become a challenging task. GIS Solution: A View application has been developed that imports output files from a post-processing program of the hydrodynamic and salinity model and creates production-ready layouts that graphically communicate the complicated model results. Graphical visualization of summarized time series results obtained from the model, by symbolizing a schematic link representation of the model grid, has not been possible until now. Methodology: Custom buttons are provided in an ArcView project that automatically import four model
output files, create fifty-four different symbolized views based on key hydraulic/salinity variables posted to the link schematic, and generate fifteen summary layouts that completely characterize the results associated with one model run. The process is easily repeated for numerous model runs, performing in minutes steps that conducted manually in ArcView had taken many hours or days of tedious repetition. The application utilizes "data-driven" programming concepts, where the program flow, view legend symbolization, and layout titling are controlled by the contents of ArcView tables that can be edited for each specific model run, rather than having to modify "hard-coded," case-specific Avenue scripts. The ability to rapidly generate graphics that visually portray conditions in every one of the 600+ model links, instead of the traditional practice of examining model results from a limited set of (assumed) critical, "representative" model points, has led to important new insights into the behavior of the model
and its application. Software: 1. The application is written using Avenue, in ArcView Version 2.1. 2. The MWD DSM is written in FORTRAN, and is a derivation of the California Water Resources' Delta Simulation Model, Suisan Marsh version (DWRDSM-SM). 3. The postprocessing program is written in FORTRAN.
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