Development of the multiple model broker, a system integrating stormwater and groundwater models of different spatial and temporal scales using embedded GIS functionality.

摘要

There has been increasing emphasis in recent years on studying water quality issues by evaluating watersheds as whole systems. Modeling is a common component of these studies, utilizing two or three separate models to achieve detailed examination of runoff, groundwater, and receiving water processes. Integration of the models is often through manual or semi-automated methods that perform simple reformatting of data files but do not enable the models to interact with each other as they run.; In this work, a system known as the Multiple Model Broker (MMB) was created that integrates the Stormwater Management Model (SWMM) and the MODFLOW groundwater model. Infiltration values calculated by SWMM are passed to MODFLOW as recharge, and water table elevations produced by MODFLOW are returned to SWMM. Both models run simultaneously in a synchronized fashion, exchanging data after each time increment. This enables each model to influence the other during the course of the model run.; The models communicate through an intermediate program (the Broker) using anonymous pipes, an interprocess communication capability provided by Microsoft Windows. Synchronization between the models is maintained internally within the Broker. The system is designed such that each model operates and communicates only within its own spatial and temporal domain; all conversions to reconcile differences in spatial discretization or temporal scale are handled in the Broker by embedded GIS functions. This approach ensures that additional models could readily be added to the system and activated or deactivated as needed, and represents a technique that could be used to integrate other types of models as well.; The system was tested on two New Jersey watersheds, West Milford Lake and Cranberry Lake, and found to produce satisfactory results if configured properly. However, performance is sensitive to the SWMM configuration. Subcatchments must be defined so that each is relatively uniform in elevation, because SWMM describes ground surface elevation and water table elevation with only a single value for each for the entire subcatchment. The reduction in infiltration caused by a high water table can only be accurately modeled if this simplification is reasonably accurate.