Integration with GIS of Large-Scale Water Quality Model Development and Display in the New York City Area

Gary Ostroff, P.E.  Sr. Project Manager
HydroQual, Inc.
www.hydroqual.com
gostroff@hydroqual.com

Entire Paper in MS Word Format

Keywords:  Model, GIS, Integration, Water Quality, Automation

In the course of our project work for the City of New York and other organizations, HydroQual has created many mathematical models of the region’s major water bodies.  These models generally link together our proprietary hydrodynamic and water quality models to produce a complete simulation of water movement and reaction kinetics within the subject area.  With the advent of desktop GIS, we moved quickly to fully integrate our modeling work into a GIS environment in order to realize tremendous gains in efficiency in setting up models, and to explore new ways of leveraging the value of model output by making it available in to GIS users.

All water quality modeling projects begin with the creation of a model framework or grid that defines ‘cells’, breaking up the subject area into volumes within which water quality and dynamics will be simulated.  These frameworks were developed through tedious process of digitizing points on a paper map, processing with a FORTRAN routine, and adjustment by engineers with the required experience in grid design.  By developing software, first in ARC/INFO, then ArcView, to allow engineers to perform this task within a GIS, the development time was cut by an order of magnitude.

Before this integration effort began, our modeling work was completely separate from our GIS work, and model output was displayed in black and white graphs or animations created with our UNIX based proprietary data post-processing system.  In either case, it was not possible to directly relate the model results to digital map data that is available to users of GIS.  HydroQual is now pursuing ways to animate model output within the GIS environment using specialize programs or available extensions.  The investigations required for this work returned us to the consideration of may interesting and fundamental questions about the representation of multi-variable data in maps, digital or traditional.