The consolidation of quality satellite imagery and the ability to automate the analysis/classifications of land cover have resulted in new and cost-effective mapping capabilities. Cutting-edge image interpretation capabilities are being used by municipalities, arborists, academics and researchers. Specific information relative to everything from tree canopy to pervious and impervious surfaces and how they might affect stormwater conditions in a community can be extracted using this data.
For example, RFPMappingLLC, Crystal Lake, Ill., captured 4,000-square miles of custom, high-resolution satellite imagery in southern Wisconsin and the Chicago area. This vast set of imagery has been processed and analyzed by remote sensing/analysis provider NCDC Imaging of Colorado Springs, Colo., resulting in land cover data and imagery. The uses for such data are wide ranging.
“The scale, compatibility and immediate availability of the data support the needs of most communities and enable them to employ better stormwater
management and urban tree planning,” said Bill Peel, RFPMappingLLC.
The village of Bull Valley, a small municipality in McHenry County, Ill., will utilize the data set for an in-depth look at six classes of land cover, generated through a proprietary process called accelerated feature extraction (AFE). AFE, developed by NASA and the U.S. Department of Defense, is a process by which large tracts of imagery can be analyzed and features mapped. It is a time- and cost-efficient alternative to more conventional manual mapping procedures.
The same data analysis has also been used in the Tree by Tree — The Mile High Million tree planting initiative in Denver. The entire community was assessed for current tree canopy coverage. The results were combined with additional remotely sensed data to determine which sites throughout the city were best suited for additional tree plantings.
“The Denver project was a great demonstration of how land cover data can be used to convey information in an effective and easy-to-understand way while
supporting a multi-faceted project,” said Ian Hanou, NCDC Imaging. “The data was a big support component for planning and outreach throughout the development of the project.”
The concept of monitoring and assessing urban forestry is often associated with manual inventory and periodically hand-tracked or manipulated GIS interpretation of existing — but often antiquated — aerial mapping. In the case of satellite imagery acquisition, however, the resulting analysis gives details on tree canopy, impervious surface, irrigated turf, non-irrigated turf, bare soil and water features. This data is compatible with existing GIS systems and software and allows for the determination of new land statistics, as well as a baseline for future assessments.
Hyperspectral imaging analysis is a combination of imagery from fixed-wing aircraft and ground samples. As opposed to satellite imagery, which is typically comprised of four bands, hyperspectral imaging is the collection of 250 narrow bands. This high degree of “spectral resolution” is useful for identifying very specific classes of objects on the ground. For example, RFPMappingLLC, in concert with NCDC Imaging, completed a hyperspectral collection for the City of Milwaukee and Mequon, Wis., concentrating on the location of ash trees in those communities for the purposes of monitoring and indexing location. As the emerald ash borer created a dramatic presence in the Midwest, this was considered to be an opportunity to support the monitoring and aggressive attention that was being provided to the problem.
Through the Illinois Department of Natural Resources (IDNR), the cities of Evanston, Wilmette, Winnetka and Skokie were also incorporated into the hyperspectral collection to track and locate the existing ash tree base, as well as several other species such as oak and elm.
The ground collection process, which is completed by trained technicians using a sophisticated instrument called a spectrometer, was implemented on the same day that the fixed-wing aircraft was collecting images. These ground samples serve as a known value to which the imagery can be compared.
In addition to utilizing satellite imagery for urban tree management, municipalities can also utilize off-the-shelf satellite imagery to definitively define the relationship between pervious and impervious surfaces as it relates to the effect of municipal water management, aquifer and recharge elements, as well as the immediate ability to understand the effect of run-off and, ultimately, future water availability for communities.
GIS technology/mapping finds itself in the midst of so many arenas, including arbor management/urban forestry. Trying to manually keep up with planning demands from those with foresight or those simply trying to keep our earth green is no longer efficient or cost effective. For interested parties from government officials to local citizens, the environment and quality of life are significant issues. By taking advantage of cost-efficient, off-the shelf data analysis or other innovative technology tools, planning departments and arbor institutions can have a definitive effect on landscape utilization, tree planting and boost the general health of our earth.
Information provided by RFPMappingLLC and NCDC Imaging.