Modeling California's Water Resource Systems with CALSIM

Abstract

Simulation of large-scale water resource systems for planning studies requires a flexible and efficient modeling tool to assist in the evaluation of rapidly changing alternatives. The California Department of Water Resources (DWR) has developed a general-purpos e river basin simulation model, CALSIM, that empowers users to quickly develop system representations and easily specify or modify operational criteria. CALSIM represents a fundamental change in the modeling approach used to simulate the operation of California's water resource systems, particularly the coordinated operation of the Federal Central Valley Project (CVP) and the California State Water Project (SWP). Model users now specify the system objectives and constraints as input, rather than embedding the simulation goals and logic in thousands of lines of procedural code as is common in traditional simulation models. A new modeling language, Water Resources Engineering Simulation Language (WRESL), has been developed to serve as an interface between the user and the linear programming/mixed integer linear programming solver, time-series database, and relational database. The physical description of a water resource system and related operating criteria are entirely expressed in WRESL. The WRESL expressions can be compartmentalized to provide for a highly organized arrangement of logical units and to serve as self-document ing modules. A number of built-in features are currently available in WRESL, but the use of advanced computer science tools such as Java and JavaCC in the development of WRESL allow for rapid inclusion of additional functions and syntax. CALSIM is intended to replace the California Department of Water Resources' existing simulation model, DWRSIM, as well as PROSIM, another simulation model of the SWP/CVP system extensively used by the U.S. Bureau of Reclamation. However, the structure of the CALSIM engine is highly generic, such that the model can be applied to many other water resource systems.