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THE USE OF NTM DATA FOR THE ACCURACY ASSESSMENT OF LANDSAT DERIVED LAND USE/LAND COVER MAPS
Citation:
Jennings, D B. THE USE OF NTM DATA FOR THE ACCURACY ASSESSMENT OF LANDSAT DERIVED LAND USE/LAND COVER MAPS. Presented at National Technical Means Conference, Denver, CO, July 24-26, 2001.
Impact/Purpose:
Overarching Objectives and Links to Multi-year Planning
This research directly supports long-term goals established in ORD's multi-year research plans related to GPRA Goal 2 (Water Quality) and Long Term Goal WQ-2 Assessment of aquatic systems impairment. Relative to the GRPA Goal 2 Water Quality multi-year plan, this research will "provide tools to assess and diagnose impairment in aquatic systems and the sources of associated stressors" and "provide the tools to restore and protect aquatic ecosystems and to forecast the ecological, economic, and human health outcomes of alternative solutions" (Water Quality Long Term Research Goals 2 and 3).
Subtask 1 - Impervious Surface Evaluation
This subtask addresses the development of impervious surfaces estimators for local to regional scale assessments of watersheds and their landscape relationship to stream ecology. The amount of impervious surface area in a watershed is a key indicator of landscape change. As a single variable, it serves to integrate a number of concurrent interactions that directly influence a watershed's hydrology, stream chemical quality, and in-stream habitat. It is our working hypothesis that impervious surface area within a watershed, as an independently mapped predictor variable, can be used to generally track a range of watershed ecological parameters (e.g., NPS pollution, biological integrity, TMDLs) that are of concern to local, state and federal environmental managers. The specific objectives of this research are: 1) to quantitatively evaluate the varying remote sensing methods used in mapping impervious surfaces at multiple scales (local to regional), and 2) to relate the varying levels of impervious surface area in watersheds to the environmental condition of multiple water resource endpoints such as streamflow, temperature, and biota.
Subtask 2 -- Landscape Assessments and Evaluations of Best Management Practices: Watershed Demonstrations
Best Management Practices (BMP) encompass a range of strategies to reduce water pollution related to urban and agricultural activities. EPA, through Section 319(h) of the Clean Water Act [PL 92-500], provides grants to states to implement BMPs in areas with suspected or known water-quality problems. Grants for implementation of BMPs have not been tracked or monitored to document their effectiveness. Although effectiveness can be measured in many different ways, one straightforward but important measure is existence. Implementation of BMPs is a voluntary process and actual implementation is not always executed (Nowak 1992). The primary objective of this project is to assess the feasibility of using high-resolution aerial photography and other remotely sensed data to identify the existence of BMPs that were planned under the 319 program. An additional objective is to evaluate the effectives of BMPs implemented by examining monitoring data from about 5 sites in the OW National NPS monitoring system.
There are several potential benefits to determining the feasibility of using the aerial photography for identifying BMPs: 1) since BMP implementation is voluntary and some may not be implemented due to a variety of social and economic factors (Nowak 1992), remote detection of BMPs can provide data to estimate the ratio of BMPs implemented to BMPs planned; 2) remote detection of BMPs provides validation data that can be input into EPA's Grants Reporting and Tracking System (GRTS), and 3) remote monitoring of BMPs over time could be used to develop data on BMP lifespans, providing important data related to social- and cost-effectiveness.
Subtask 3 -- TMDL Non-point Source Assessment Tool
This subtask involves the development of a software tool to assess the potential risks of water bodies to exceed TMDL threshold values established by States. When completed, the tool will allow the user to evaluate watersheds over entire regions. The too
Description:
National Technical Means (NTM) data were utilized to validate the accuracy of a series of LANDSAT derived Land Use / Land Cover (LU/LC) maps for the time frames mid- I 970s, early- I 990s and mid- I 990s. The area-of-interest for these maps is a 2000 square mile portion of the Delaware River watershed located in the Catskills mountain area of New York State. The maps were produced as part of a scientific study investigating the relationship of landscape pattern and change on water quality. Scientifically validating the accuracy of the LU/LC maps was integral to quantifying the relationship. NTM data provided an alternative to aerial photographic methods that are traditionally utilized in these types of assessments. The size of the watershed and the need for multiple historical coverages were factors that prohibited the acquisition of complete aerial photographic coverage. Results of the assessment ranged from 88% for the mid- I 970s maps to 90% for the early- I 990s maps to 95% for the mid- I 990s maps. This is the first accuracy assessment utilizing NTM data by USEPA scientists and it's successful completion points to NTM as an alternative data source when the acquisition of aerial photography is problematic. NTM is classified national asset data and the source attribution for open-science publishing was limited to "independent high resolution imagery" only. This limit on attribution may impact peer review processes and as such should be taken into consideration in advance of any open-science research proposal.