Using GIS in a Modeling Workflow

GIS itself is an incredibly valuable tool for spatial analysis and modeling, but there are a lot of models out there designed for highly specific purposes that are not yet and maybe never will be fully implemented in a GIS framework.  However, the spatial display, analysis, and data management capabilities of GIS can be used to greatly streamline the modeling workflow.  The diagram below shows an example of how GIS can act as the cornerstone of a highway noise modeling workflow. 

Integrating Highway Noise Models with GIS

What is The Geographic Approach?

ESRI has been using the phrase “The Geographic Approach” for some time, in several different contexts. Jack Dangermond has used it to describe his high-level vision for the application of geospatial technology, perhaps best illustrated at the 2007 International User Conference which employed the theme “GIS—The Geographic Approach.”

“Geography, the science of our world, coupled with GIS is helping us understand the Earth and apply geographic knowledge to a host of human activities.

“The outcome is the emergence of ‘The Geographic Approach’—a new way of thinking and problem solving that integrates geographic information into how we understand and manage our planet. This approach allows us to create geographic knowledge by measuring the Earth, organizing this data, and analyzing/modeling various processes and their relationships. The Geographic Approach also allows us to apply this knowledge to the way we design, plan, and change our world.

“The Geographic Approach is not a new idea. It is how geographers study and analyze our world. It was perhaps best articulated by Ian L. McHarg in his book Design with Nature, where he lays out a philosophical context for why and how humans should manage these activities within natural and cultural landscapes.”

—Jack Dangermond, “GIS—The Geographic Approach,” ArcNews, Fall 2007

“The Geographic Approach” has also been used by ESRI in the context of applying GIS technology to problem solving in various industries. For example, in 2008 ESRI put together a very successful worldwide seminar series focused on Public Works professionals, the core of which was improving operational awareness and efficiency by using The Geographic Approach. And the 2008 ESRI Federal User Conference, with its vision of how state and local governments can support a framework for a national GIS data model, has been promoted using the phrase “The Geographic Approach for the Nation.”

So at a higher level, The Geographic Approach is a useful framework for communicating the value of using GIS. Another, more hands-on view of The Geographic Approach is as a method for spatial problem solving and decision making. The earliest reference I found for this GIS methodology is on page 11 of The ESRI Guide to GIS Analysis, Volume 1: Geographic Patterns & Relationships by Andy Mitchell (ESRI Press, 1999), but in reality people have been using these methods since before maps were put in to computers.

The Geographic Approach as a methodology consists of a five-step inquiry process: Ask, Acquire, Examine, Analyze, and Act. You might even think of it as sort of like The Scientific Method for GIS professionals.


The first step to approaching a problem geographically involves framing the question from a location-based perspective. What is the problem you are trying to solve or analyze with this project and where is it located? Being as specific as possible about the question you’re trying to answer will help you with the later stages of The Geographic Approach such as how to structure the analysis, which analytical methods to use, how to present the results, and who will use the results.


After clearly defining the problem you wish to solve, it is necessary to determine the data needed to complete your analysis and then ascertain where that data can be found. The type of data and coverage or map features needed for your project will help direct your methods of data collection and analysis. Conversely, if the method of analysis requires detailed and/or high level information, it may be necessary to create or calculate the data used.


You will not know for certain if the data you have acquired is appropriate for your study until you actually examine it. The data ultimately selected for your analysis depends on your original question or questions as well as the results that you are seeking and how those results will be used. This in turn is dependent on how precise the data must be to answer the original questions. The acquisition of unique data can sometimes be both expensive and time consuming. More detailed data can be more expensive and require greater processing, but can also provide more precise results.


In this step the data is processed and analyzed based on the method of examination or analysis you have chosen, which is dependent on the results you hope to achieve. An understanding of the effects of parameters you have established for the analysis is critical, as well as the algorithms being implemented so that you can correctly interpret the results. Do not underestimate the power of ‘eyeballing’ the data. Looking at the results can help you decide whether the information is valid or useful, or whether you should rerun the analysis using different parameters or even a different method. GIS makes it relatively easy to make these iterative changes and create new output.


The results and presentation of the analysis is an important part of The Geographic Approach. The results can be shared through reports, maps, tables, charts, or on the web. You need to decide the best method to present your analysis. You can also compare the results from different analyses and see which method presents the information most accurately.

Using a methodology such as The Geographic Approach formalizes the analytic process with GIS, which allows a clearer understanding of the results and promotes a supportable response. By applying The Geographic Approach to help us solve complex problems, we can make better decisions, conserve resources, and improve the way we work.

“Clearly, our world needs a new approach, an approach that changes how we see and do things, an approach that allows us to get more knowledge about and awareness of all of the problems we are facing,” Dangermond said at the 2008 ESRI Federal User Conference in Washington, D.C, in reference to worldwide challenges such as growing population, global warming, and resource shortages. “We need a new approach that allows us to apply what we know to all the decisions we are collectively going to carry out, and so the notion of a Geographic Approach is emerging.”