A Better View from Above
Environmental research, mapping and land condition assessments of levees, runways and other critical infrastructure is getting much more specific thanks to improved aerial imaging technology.
By Steven Apfelbaum
What once required arduous on-the-ground testing and evaluation can now be done from high above. A new imaging technology acquired by Applied Ecological Services (AES), with Ayres Associates, allows mapping of environmental projects and conducting of aerial surveying—performing quick, cost-effective land condition assessments for design and engineering projects. The defense-grade, digital, multi-spectral aerial camera is being used to conduct imaging flights to map, measure and monitor a suite of land and aquatic-based features. Typical applications include mapping land cover change, impacts of storms on cities, crops and forests, and damage to infrastructure such as airport runways, highways and other critical structures.
The technology can be applicable to a variety of environmental and land-assessment projects, including military- and commercial-related. For one project for instance, a client was considering a renewal of a very expensive multi-year lease on a 31-mi long pipeline. Prior to signing the lease, both parties wanted to know the precise condition of the pipeline. An impasse resulted where neither the lessee nor the lessor knew exactly how to determine the pipeline’s condition. AES was retained to fly over and collect images of the pipeline route and used spectral enhancement and classification methods—utilizing the infrared band in particular but also the red, green and blue bands. The assessment located hundreds of leaks in the pipeline. This discovery resulted in a prompt cancellation to continue leasing the pipeline for fear of product losses through the leaks as well as liability concerns for damaging the environment with the leaking materials.
For AES, this new high-resolution imagery would have been very beneficial over the past decades of working on military lands and other properties. During its studies of track vehicle impacts to natural resources at military installations—including Fort Knox, Ky.; Fort Riley, Kan.; Fort Carson, Colo.; and Fort Irwin, Calif.—the firm could have used the technology to accurately map and measure the impacts. The benefit of the imagery is that it can help in monitoring compliance; and ultimately, it will help improve downstream water quality in lakes, streams and potable water supplies, and in erosion control and stabilization on track vehicle training lands.
Without such high-resolution aerial photos, the early studies AES conducted for the military required painstaking on-the-ground field measurements. If the 4-band multi-spectral imagery had been available, it could have been used to measure damages to soil such as where track vehicles turned and sheared vegetation, creating bare soil areas. Instead of weeks in the field measuring impacts, today just a few days of measuring and confirming impacts would be required.
MAPPING REAL-TIME EVENTS
AES also is mapping and measuring damages from extreme weather events that are causing stormwater runoff and the distribution of suspended solids, nutrients and contaminants from source areas. The imagery enables the firm to link source areas to growths of invasive aquatic plants, such as where Eurasian watermilfoil proliferates in many water bodies.
The key to using this technology is an ability to schedule flights in a “just-in-time” manner. For ecological projects, AES needs to shoot images during narrow windows of time—for instance, right after a storm event to map runoff conditions. Another just-in-time application is to collect imagery when an invasive plant is in bloom, for mapping its distribution.
The combination of the Leica RCD30 camera and Cessna single-engine plane allows researchers to fly low and slow, and more cost-effectively collect imagery as fine as 2-in resolution, which is not possible with faster, larger, less efficient aircraft.
AIDING REGULATORY PROCESSES
The imagery is not just saving considerable time in the field and helping to achieve a more accurate understanding about complex land and natural resources issues. The imagery also allows regulators, designers, landowners and other owners and end-users to share a common understanding of landscape issues, saving both time and money. With regulators, this builds trust, also saving time and cost.
For engineering, planning, and regulatory submittals, the ability to reference detailed, accurate aerial photography is essential. When regulators clearly see and understand what is being proposed, there is a better tendency for applications to rise to the top of the review pile, avoiding often lengthy review delays.
Use of this imagery for a major mining company on one of the largest Superfund projects in the country resulted in several years of some potentially very costly permitting issues being shaved off and a resolution being reached much earlier. The aerial photos accurately documented and communicated to all parties that reclamation had been successfully accomplished in some conspicuous locations and it indicated additional work was needed where plantings were not as well established.
Operations and maintenance of industrial lands, including the infrastructure of facilities and grounds, are supported with this imagery and the types of advanced analyses that can be conducted. If an owner is trying to optimize vegetation management in utility corridors the imagery will not only help determine which species need management, but also where the management is needed and what potential environmental concerns are likely with water quality, stormwater runoff, or poor soils.
Pavements and airport runways are another place where the imagery is being used for accurately mapping cracks and monitoring their expansion. Early detection of such problems, which are not detectable with on-the-ground inspections, can be provided with the infrared band. Often, underlying moisture or cavitation issues within the pavement can also be assessed.
In roadway embankments and levee inspections (which is a major program of the U.S. Army Corps of Engineers), the imagery and GIS analysis can deliver early detection of slope failure risks and provide a clear mapping record, with comprehensive statistics. Such statistics include location, extent, condition and potential area of impact associated with failing or degraded locations. And the imagery can detail existing conditions, to include measurement of vegetation cover and bare soil coverage, as well as exposed infrastructure such as pipes, culverts and control structure failures. The technology could be timely given that levees have been rated among the weakest national infrastructure by the American Society of Civil Engineers, receiving a “D-” in its 2009 Report Card.
For clients with large land holdings, some perhaps being leased for agricultural production and others being preserved for conservation purposes, the imagery can be used for myriad purposes. Monitoring agricultural drainage infrastructure—tiles, ditches or control structures—is very accurately and efficiently mapped. Monitoring crop acreage to determine cost sharing, and even crop yields, has been conducted for some crops.
The real allure of the new technology is the crystal clarity offered for land and water systems, as well as buildings and other infrastructure facilities that commercial and federal clients must ensure are working properly to ensure public safety.
AES was struck by the usefulness of the imagery when the plane happened to be flying the Mississippi River one winter afternoon between downtown Minneapolis and St. Paul, Minn. As it happened, the pilot and camera operator flew over the Metrodome, home to the National Football League’s Minnesota Vikings, and captured a striking image of the collapsed Metrodome stadium roof. The photographs taken were, in fact, “just-in-time,” and showed the locations and size of the failed roof.