Stories From The Field

Analyzing Sedimentation Processes to Guide Conservation in Oregon

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Issue

The Wetlands Conservancy developed a conservation plan for the Yaquina Estuary in Lincoln County, Oregon (2011). Part of the analysis required understanding sedimentation processes and threats throughout the watershed. Clear-cut timber harvests have long been identified as a potentially significant contributor to excess sediment loads in streams, and eventually, to estuaries. However, timber harvest records on private lands are not centralized or available in GIS format, making it difficult to quantify this potential threat.

Process

The Wetlands Conservancy used NOAA’s land cover data to detect timber harvest activities over five-year intervals (1996-2001 and 2001-2006). This selection of land cover change data, which was combined into a single coverage, gave an approximation of clear-cut timber harvest areas. A comparison with pre- and post-dated aerial imagery confirmed the utility of the approach.

Impact

The land cover data provided a quick and reasonably accurate representation of clear-cuts. This information was analyzed along with impervious surface data (from the U.S. Geological Survey’s National Land Cover Database), allowing the Conservancy to better understand freshwater inputs from these features and their effects. This information, included in the Yaquina Estuary Conservation Plan, is guiding conservation efforts and promoting the selection of acquisition and restoration projects that address critical watershed and estuary restoration opportunities.

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NOAA Coastal Change Analysis Program data were used to analyze land cover in the Yaquina Basin, Oregon. View PDF version of this map. (Download Adobe Reader)
Wetlands Conservancy uses National Land Cover Database and C-CAP Regional Land Cover data to detect timber harvest activities in the Yaquina Estuary
USGS National Land Cover data and NOAA Coastal Change Analysis Program data were used to calculate impervious surface area in the Yaquina Basin. View PDF version of this map. (Download Adobe Reader)

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