3-D GIS System Throws Public Discourse in Relief
- By Meg Misenti
- Oct 31, 1997
A few months ago, Jason Kornoff was in a tough spot, facing a room of citizens attending a public meeting about groundwater contamination in their east Los Angeles community. As geographic information systems (GIS) coordinator for the San Gabriel Basin Water Quality Authority, Kornoff was charged with describing groundwater contamination and how contaminants travel below the ground's surface, enter the groundwater and spread by natural movement within the basin.
"It took me about 10 minutes to explain it, and after I finished, I still didn't feel they understood," said Kornoff, recalling the public meeting last spring. At the time, Kornoff was using 2-D maps of the basin, which painted a static picture of the runoff, but they were misleading, especially in terms of the depth of the contamination.
The problem with 2-D maps is that most people cannot make the leap to the 3-D world when looking at a 2-D surface. "People are visual animals. It's easier to explain to someone through visual objects than through graphs and tables of mounds of data," Kornoff said. To do that, he turned to Environmental Systems Research Institute Inc. (ESRI) and its extension tool ArcView 3D Analyst, which brings an interactive 3-D perspective to the desktop.
"Now my demonstration speaks for itself," Kornoff said. "People can see the characteristics of the contamination without any explanation on my part."
"It was an incredibly powerful presentation tool," said George Lujan, an environmental consultant who sits on the City Council of South El Monte, which sits in one of four areas identified as hazardous waste sites and is targeted for cleanup. "Looking at the computer-generated maps really gives you a sense of how much water in the area is contaminated. People who wouldn't normally look at site maps are immediately drawn to critical features illustrated by 3-D imaging," said Lujan, who ran on an environmental cleanup platform and thinks such tools are ideal for public presentations, such as town hall and city council meetings.
In 1993 the California state legislature established the San Gabriel Basin Water Quality Authority (WQA) to start groundwater treatment programs in the area, which had been exposed to contamination from cleaning solvents and degreasing agents during and following World War II. The WQA is spearheading the efforts of roughly 15 agencies and community groups working to ensure the safety of the water and to prevent the contamination from spreading to nearby water supplies.
Ken Manning, who served two terms as president and is now treasurer of the board that oversees the WQA, said with the advent of the GIS tools, efforts to disseminate information to the public about the problem have been more effective. "People are getting a continuous flow of information and building on what they already know," he said. "Elected officials and policy-makers in the valley very well understand the issues relevant to water, much more so than before this tool was used."
A key benefit of the GIS tool has been that the public has been able to see a clear picture of where contamination has occurred and also where it has not.
For example, when people look at 2-D maps, they might think all the water within an area is contaminated, but that's not necessarily true. Parts of the basin are a few thousand feet deep, and contamination is often relatively close to the surface, perhaps only 200 feet to 400 feet down. The water under and around the contamination plume may be clean.
"So we actually have a large portion of the aquifer that's not polluted," said Manning, who added that the 3-D visualization "has helped us characterize it in its proper perspective. The biggest impact this has had is to help people understand the magnitude of the pollution."
The 3-D tool also makes it clear how contamination may have spread from a point of origin.
"If you can imagine smoke coming off a smoke stack, and how it starts at one point and disperses through the air and then if you flip it upside-down, that's what a contamination plume looks like," Kornoff said. "Often, it looks like it is pointing directly at the site that dumped the chemicals."
Communicating in 3-D
The advent of a 3-D visualization tool for the desktop means public-sector users, who might have been priced out of the market for earlier versions of such software, have a powerful public-policy tool at their disposal.
"You're getting true 3-D geographic data at a desktop price," said Rich Turner, product manager of ArcView at ESRI. "For a very large majority of geographic data users, this is the first time in the desktop world there's been an affordable mechanism for viewing data from a 3-D perspective."
ArcView's 3D Analyst extension tool runs on Microsoft Corp.'s Windows 95/NT and select Unix platforms.
The software allows users to rotate and "fly through" scenes, offering a link between 3-D visualization and GIS data. "That, in and of itself, is a huge thing," Turner said. The software also gives users 3-D specific tools for line-of-sight and volumetric calculations as well as for creating data modules to represent surface features and contours.
3D Analyst "will take desktop mapping to the next level," Turner said. "It's like going from black-and-white to color [TV].
-- Meg Misenti is the editorial assistant for civic.com. She can be reached at firstname.lastname@example.org.