DOGAMI Open-File Report Series

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Open-File Report O-11-14, Stream channels of the Central Willamette Valley, Benton, Linn, Marion, and Polk Counties, Oregon, scale 1:36,000, by Daniel E. Coe.

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Lidar-based map; actual size 60 x 72 inches, scale 1:36,000.

Also see northern Willamette Valley stream channels and Tualatin Valley stream channels maps.

map view of DOGAMI Open-File Report O-11-05: Stream channels of the northern Willamette Valley, Clackamas, Marion, Polk, Washington, and Yamhill counties, Oregon

This map depicts the Willamette River as it flows north past Corvallis toward Salem. This region, known as the Central Willamette Valley, is bound to the north by the Salem Hills, to the east by the Cascade Range foothills, and to the west by the Coast Range. Cities in this region include Corvallis, Albany, Lebanon, Stayton, and Monmouth-Independence. This area encompasses fertile farmlands in the lowlands, productive vineyards in the western hills, and dense forest in the Cascade Range. Much of the region's fertility is a result of sediments left behind by ice age floods, known as the Missoula Floods, that occurred between 15,000 and 12,700 years ago.

To show the complex history of channel formation and migration that occurred in the Central Willamette Valley after the floods ended, a blue gradient was applied to the floodplains. This gradient shows the relative elevation of the floodplain above the adjacent channels.

The lidar data used to create this map were collected from a light aircraft carrying a highly accurate laser scanner. The scanner makes over 100,000 measurements each second to build up a three-dimensional "point cloud" model of the surface of the earth and the vegetation and structures on it. A computer sorts the points, separating those that measure the ground from those that measure other objects such as trees or buildings. Images derived from these sets of points are then merged with other forms of digital data to create this map.