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HOW FAR TO THE NEAREST ROAD?
Citation:
Wickham, J D. AND K. H. Riitters. HOW FAR TO THE NEAREST ROAD? Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Impact/Purpose:
The primary objectives of this research are to:
Develop methodologies so that landscape indicator values generated from different sensors on different dates (but in the same areas) are comparable; differences in metric values result from landscape changes and not differences in the sensors;
Quantify relationships between landscape metrics generated from wall-to-wall spatial data and (1) specific parameters related to water resource conditions in different environmental settings across the US, including but not limited to nutrients, sediment, and benthic communities, and (2) multi-species habitat suitability;
Develop and validate multivariate models based on quantification studies;
Develop GIS/model assessment protocols and tools to characterize risk of nutrient and sediment TMDL exceedence;
Complete an initial draft (potentially web based) of a national landscape condition assessment.
This research directly supports long-term goals established in ORDs multiyear plans related to GPRA Goal 2 (Water) and GPRA Goal 4 (Healthy Communities and Ecosystems), although funding for this task comes from Goal 4. Relative to the GRPA Goal 2 multiyear plan, this research is intended to "provide tools to assess and diagnose impairment in aquatic systems and the sources of associated stressors." Relative to the Goal 4 Multiyear Plan this research is intended to (1) provide states and tribes with an ability to assess the condition of waterbodies in a scientifically defensible and representative way, while allowing for aggregation and assessment of trends at multiple scales, (2) assist Federal, State and Local managers in diagnosing the probable cause and forecasting future conditions in a scientifically defensible manner to protect and restore ecosystems, and (3) provide Federal, State and Local managers with a scientifically defensible way to assess current and future ecological conditions, and probable causes of impairments, and a way to evaluate alternative future management scenarios.
Description:
Increases in impervious surface area lead to declines in chemical and biological indicators of water quality .Roads are an important aspect of impervious surface, and distance to roads is an indicator of the potential threat to aquatic and terrestrial ecosystems. Although roads are expected to be common in urban settings, the pervasiveness of roads in rural ecosystems is not well appreciated. We combined national land..cover (MRLC/NLCD) and road maps to measure the proportion of land area that was located within nine distances of the nearest road of any type, and summarized the results for 2,108 watersheds nationwide. Overall, 20% of the total land area was within 127 meters of the nearest road, and the proportion increased rapidly with distance such that 83% was within 1,061 meters of a road. Geographic regions with more than 60% of total land area within 127 meters of a road may be at greatest risk of cumulative ecological impacts from roads. Those regions include nearly all coastal zones as well as substantial portions of the southeast Piedmont, the southeast coastal plain, and the Ohio, Brazos, Colorado, San Joaquin, and Sacramento River basins. This research demonstrates how an interagency approach based on principles of landscape ecology and consistent national databases can be used to identify regions of the country at highest risk to road-mediate adverse impacts on aquatic and terrestrial ecosystems.