Term Project Outline
CE397 GIS in Water Resources
University of Texas at Austin

Using ArcView as a User Interface for naUTilus

By Cindy How
Spring 1997


Table of Contents

Note: This is a work in progress.

Goals and Objectives

The goal of this project is to work towards creating a user interface in ArcView through which the FORTRAN model naUTilus will be run. The results of the model will also be displayed.

To accomplish this, the programming language Avenue will be used. As an additional objective, I hope to gain some level of proficiency in using Avenue.

While making a complete interface between ArcView and naUTilus for the purpose of this term project may not be an achievable goal, the desired goal is to enable data output from the naUTilus model to be visually displayed in ArcView.

Work done towards creating an input interface will also be described.


With the passing of the Clean Air Amendments of 1990, industrial sewers have received more focus as a source of Hazardous Air Pollutants (HAPs). Of particular interest are emissions of volatile organic compouds (VOCs) in petroleum refining and organic chemical manufacturing. VOC emissions occur at drains or manhole covers within specific process units (referred to as ISBL or inside the battery limit) or from manhole covers or elevated vents in sewers which collect ISBL discharges (referred to as OSBL or outside the battery limit). In large and mid-sized refineries or chemical manufacturing facilities, emissions may be distributed over thousands of openings, making monitoring programs unfeasible. In the absence of monitoring, VOC emissions are predicted using emission factors or mathematical models. naUTilus was developed to address this issue, as an improved method over highly conservative models which tend to overestimate emissions.

However, present use of naUTilus requires familiarity the numbering scheme of network components and branch connectivity in order to create a lengthy input file. By creating a user interface in ArcView, this project makes naUTilus easier to use, increases the power of the model by facilitating it's application to larger facilities, and spatially represents the input and output.

Introduction to Industrial Sewer Networks

Industrial sewer networks can be classified into two sections. The several drains and pipes which are involved in a specific process unit is designated as "inside the battery limit" (ISBL). Several ISBL units will drain into a larger set of main lines categorized as "outside the battery limit" (OSBL).

Several features comprise a sewer network: reaches, nodes, drops, manholes, and drains. Liquid-to-air mass transfer occurs in the reaches (also referred to as branches) and at drop structures. Emissions occur at manholes, drains, and elevated vents by air exchange.

Introduction to naUTilus

naUTilus is a computer model written in FORTRAN which analyses the data from an industrial sewer network and predicts the emissions of volatile organic compounds (VOCs) from the network. It is the product of a great deal of research done by several individuals under the supervision of Dr. Richard Corsi at the University of Texas at Austin.

naUTilus applies mass transfer principles to estimate liquid/gas mass transfer in reaches and fluid mechanic and heat transfer principles to calculate air exchange rates between the sewer network and the ambient atmosphere. Several relationships used in naUTilus were experimentally derived. The inputs to naUTilus are the specifications of an industrial sewer network: flow rates, concentrations, temperatures, and sewer characteristics. naUTilus outputs the emissions and flow rates in that sewer network. The two sections of a sewer network (OSBL and ISBL) are handled by different sets of code in the naUTilus model

At present, a great deal of knowledge of the model is needed to successfully run the naUTilus program. The input consists of a text file; it is essentially a string of numbers representing the system it is to model in a very specific format. To see an example input file, click here. Similarly, the output is a text file listing the output. To see an example output file, click here. The example files were for a sewer network consisting of 110 branches and 83 nodes.

The input file describes flow and concentration inputs to the sewer network as well as the connectivity of the branches and nodes. Information on the chemical of interest, pipe diameters and slopes, drop heights and locations, opening size, temperature, and wind speed are also a part of the input file.

To facilitate the use of naUTilus, a graphic user interface (GUI) is desired. Input and output could then be directly associated with a visual (schematic) of the sewer network . The user will be prompted for input and sewer characteristics will be more easily modified. Results would also be output in a visual, easy to interpret display.

The naUTilusArcView Interface

The naUTilus/ArcView interface is created using a series of Avenue scripts. Avenue is an object oriented programming language specific to ArcView. Through Avenue, the digitized map entered to ArcView will be able manipulated to create the input file needed by naUTilus. The model will also be executed from within ArcView. In turn, ArcView will read the model output and, through Avenue scripts, display the data in the desired visual format.

Working with OSBL

To define a term project of reasonable scope, the selected goal was to enable ArcView to read and display naUTilus output for an OSBL system.

Completed Steps

The following steps were required to display naUTilus data in ArcView.


Shown below is an OSBL unit:
These results are shown on an actual industrial sewer network for the chemical Benzene. Hypothetical inputs for flow, temperature, and concentration values were used.

Further enhancements

Other works in progress to enhance the naUTilus/ArcView interface include:

Also, while the work done in this project was done on a schematic of an actual OSBL unit, that schematic was not to scale. The length of each branch had to be approximated and manually assigned. One goal is to get a to-scale map of a facility. Branch length could then be read directly from the digital file.

In Progress

Several steps have yet to be completed for the OSBL portion of the naUTilus code. Work is continuing on all steps.

Working with ISBL

Work similar to that done for OSBL is being done for ISBL, some in parallel with steps yet to be completed for OSBL. In particular, an input interface for both OSBL and ISBL is in the early stages of development.

Some of the work completed for ISBL includes:

ISBL unit showing flagged nodes:

These flagged nodes represent drains at which flow enters the system. The node on the far left is the terminal node in the system, where flow will be discharged to an OSBL system.


Several scripts were written to complete this project and have been mentioned previously in this document. They are not in their final format, as they will likely be modified before the entire research project is complete. However, for the purpose of this term project, they are functional. Each script must be run from the script with the view as the immediately underlying document.

Eventually, these scripts will all be run from the button or tool bar in ArcView.

Other possible uses of ArcView/naUTilus

In addition to providing a user friendly interface, the integration of naUTilus and ArcView allows for immediate "hot spot" analysis and the possibility of fenceline risk assessment and municipal sewer applications. "Hot spot" analysis consists of identification of problem areas where emissions may exceed tolerance levels. Fenceline risk assessment would consist of using dispersion models and naUTilus predictions to estimate contaminant levels at the boundaries of a plant. Being able to spatially orient the industrial sewer network would make fenceline risk assessment possible. Applying naUTilus to municipal sewers would further utilize the spatial capabilities of GIS. Emissions could be seen on a wide scale and in relation to other spatial data: streets, streams, land use, and various other data.

Data Sources and Human Resources

Data on some industrial sewer networks is being sought from Shell. This data will include a network schematic, branch lengths, branch diameters, drop structures, flow rates, concentrations, and temperatures.

Presently working on the naUTilus model is David Olson, one of Dr. Corsi's former students who now works for him as a Research Engineer.

On the GIS/ArcView side of this project, I am receiving help from members of Dr. Maidment's research group. Thanks to all who are contributing to this project!

I would also like to thank the Environmental Solutions Program (ESP) for funding this project.

Updated and Continuing Work

To see the work that has continued and been completed since the completion of CE397K-Spring 1997, see the document Research Project Update.


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Last edited: 4/23/97