Until recently, the U.S. Border Patrol, San Diego Sector, was an underfunded, understaffed operation with inadequate resources. But over the last five years, the federal government has transformed it into a well-equipped security operation with over 2,000 agents. Before the Clinton Administration initiated Operation Gatekeeper in 1994, apprehensions of illegal migrants in the area ran well over a half million annually. Since then, the numbers have dropped by 75 percent.

Operation Gatekeeper provided extensive funding and resources to restore integrity and safety to the San Diego Sector. In addition to major increases in personnel, resources andinfrastructure, the sector recently acquired geospatial and IT systems to assist in covert detection and speedy identification of smugglers and migrant traffic. These applications have already advanced the sectors intelligence and surveillance capabilities well beyond what they were in the mid-1990s.

At that time, the 66 miles from Imperial Beach, Calif., to the Anza Borrego Desert in the east -- officially designated the San Diego Sector -- was the most vulnerable portion of the U.S. southern international boundary, accounting for nearly one-fourth of all illegal border crossings throughout the Southwest. As illegal traffic climbed to tens of thousands annually, crime rates and property damage in border communities soared, and the quality of life in neighborhoods deteriorated.

But soon after Attorney General Janet Reno visited the area in 1993 and saw the situation first hand, funding and resources poured in. By the end of the decade, wire fencing through urban and beach areas of the border were replaced with a wall and lit with powerful lighting. Today, a fleet of helicopters with forward-looking infrared systems provides continual aerial coverage, and Zodiac boat teams patrol the river and ocean approaches. Special units with vans, bicycles and ATVs and on horseback cover the sector from the heavily populated urban coast to the remote eastern terrain.

Tracking with Technology

To further counter the movement of illegal traffic, San Diegos technical division began developing applications using GIS to integrate and analyze data from GPS, remote sensing, false infrared aerial imagery, night-vision scopes, seismic and infrared detectors and digitally scanned fingerprints.

One of the first applications was a GIS-based network of seismic and infrared sensors placed in strategic locations to expand surveillance and detection capabilities. Persons or vehicles passing over, through or nearby these devices trigger signals that are picked up and relayed by repeaters to the dispatch center and to each of the sectors nine stations. The time and the coordinates of the alerting sensor are displayed on a 3-D map of the area, enabling the dispatcher to estimate the migrants rate of travel.

Supervisory Border Patrol Agent John Block said the technical division is also entering the GPS survey coordinates of U.S. roads and migrant foot trails in the sector into ArcView. "Were looking at how the trail networks are changing and at how our operations are impacting movements along the border," Block said. "An increase in the number of trails helps us gauge the effectiveness of our operations. It also tells us if the traffic is moving elsewhere along the border or out of our area."

Vegetation stress analysis is also being field-tested. The sector is evaluating the ability of ERDAS Imagine software to analyze modified infrared aerial photography for chromatic differences between healthy vegetation and vegetation stressed by the passage of people and the waste they leave behind. Patrol Agent Daniel Isenberg explained that stressed vegetation shows up as a different color in the infrared spectrum than that of healthy vegetation. "The difference in color may tell us where migrants and smugglers are forming new routes, where they are laying up during the day and something about the amount of traffic along that path. From that we can change our response patterns accordingly."

Isenberg said the orthographically corrected,