Computer Assisted Decision Support System for High Level Infrastructure Master Planning: Case of the City of Portland Supply and Transmission Model (STM)

Quantitative techniques and computer-based models were first introduced into the water resources discipline in the early 1960s. Since then models developed for and applied to various aspects of managing water resources have evolved from "black box" paradigms to complex and comprehensive user-friendly interactive computer models. These efforts have been motivated by the apparent and increasing demand for more effective planning and policy making, and to aid in operating complex and often multi-objective and multi-purpose water resources systems. The success and effectiveness of water resources computer models in public agencies is impacted by the institutional framework in which the model was developed, the existence of an effective interface mechanism that can link modeler-model-user interactions, and the model's contribution to facilitate and support the decision making process. The "Supply and Transmission Model" (STM) was developed to support a large infrastructure master plan designed to explore a wide variety of water supply, water management and water transmission options for the Portland Water Bureau (PWB). The model is a highly interactive evaluation tool, allowing PWB staff to create a shared understanding of the model's assumptions and encourage the Water Bureau staff to explore how various future expansion and conservation alternatives will allow them to meet their water supply and natural resources management goals. The model has been created in the STELLA Research 5.1.1 simulation environment. One of the purposes of this paper is to discuss the critical factors that have contributed to the acceptance of STM as a planning decision support tool for the PWB.