New Jersey Water Science Center
Great Falls of the Passaic River at Paterson, N.J.
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Passaic River Basin Flow Model
Project Title: NJ193 - Passaic River Basin Flow Model
The overall objective of this project is to develop the hydrologic framework that will support future TMDL water-quality modeling efforts in the Passaic River system. The specific study objectives are as follows:
Statement of Problem
The Passaic River basin includes three of the twenty watershed management areas designated by the New Jersey Department of Environmental Protection (NJDEP) for detailed water resource studies and management planning. As part of the watershed management process, NJDEP provides a framework for interested citizens to play a key role in the process through the establishment of watershed advisory committees. The membership of these committees includes interested citizens, representatives of related industries, consulting firms, environmental groups, as well as federal, state, and local agencies. NJDEP, in cooperation with the Passaic TMDL Work Group, has determined that riverine water quality modeling of phosphorus and nitrogen in the Passaic River basin will be required to support several TMDL efforts underway. Water quality in the Passaic River basin is affected by complex river system hydraulics, groundwater-surface water interactions, non-point source runoff from mixed land uses and geologic provinces, and water quality processes in the wetlands of the Passaic River System. Because of the transient nature of the stream flows, loadings and water quality processes that need to be modeled, dynamic flow and water quality models will be required. To varying degrees, the flow and water quality models may need to simulate all of these processes or work synergistically with other models to adequately account for all significant processes. Any and all of the water quality modeling efforts in the Passaic River basin will require a transient flow model to be developed, calibrated, and validated.
Strategy and Approach
The flow model proposed for supporting planned TMDL modeling of nutrients is a USGS transient streamflow model developed by Dr. Harvey Jobson. This unsteady flow model uses a simplification of the full dynamic wave equation (Saint-Venant equation) known as the diffusion analogy or non-inertial wave equation. In addition, it uses geomorphologic principles combined with a lagranian solution scheme to provide a stable and accurate upland river flow model. This model, known as the Diffusion Analogy Flow Model (DAFLOW), can be calibrated and validated using existing stream-gage data and has been designed to work in synergy with a Branched Lagranian water-quality Transport Model (BLTM) and the Modular Finite-Difference Groundwater Flow Model (MODFLOW). The USGS and others have used the DAFLOW model to successfully model a large number of stream reaches throughout the country.