The recent post about the Mississippi River change illustrated in the Fisk maps reminded me of this lovely lidar image of the Willamette River, which encompasses the region around Portland, Oregon and south. The image Willamette River Historical Stream Channels, Oregon, 17 x 38 inches, by Daniel E. Coe (via the State of Oregon Department of Geology and Mineral Industries – DOGAMI). From their site:
This lidar-derived digital elevation model of the Willamette River displays a 50-foot elevation range, from low elevations (displayed in white) fading to higher elevations (displayed in dark blue). This visually replaces the relatively flat landscape of the valley floor with vivid historical channels, showing the dynamic movements the river has made in recent millennia. This segment of the Willamette River flows past Albany near the bottom of the image northward to the communities of Monmouth and Independence at the top. Near the center, the Luckiamute River flows into the Willamette from the left, and the Santiam River flows in from the right. Lidar imagery by Daniel E. Coe.”
Via an article in the Oregonian, the utility of LIDAR in evaluating subtle changes that wouldn’t be visible via aerial photography is evident, and the “Lidar data is collected by low-, slow-flying aircraft with equipment that shoots millions of laser points to the ground. When the data is studied, an amazingly accurate model of the ground can be mapped. It is possible to strip buildings and vegetation from the images, so that only the ground is shown. In the Willamette River poster, the shades of white and blue show elevations. The purest white color is the baseline, (the zero point, at the lowest point near Independence on the upper part of the image). The darkest blue is 50 feet (or higher) than the baseline. The shades of white show changes in elevation, between 0 to 50 feet. This brings out the changes made by the river channel in the last 12,000 to 15,000 years, in the time since the landscape was basically swept clean by the Missoula floods.”
The evocative image that is fluid and abstracted, as mentioned in the Oregonian article by the mapmaker, Dan Coe:
“The different movements of the river make the image take a liquid shape, even almost like a cloud of smoke. This shows the magic of lidar.”
You can download high resolution PDF of this map (52.3 MB) from the site for printing. As an added bonus, their site offers a number of interesting Oregon maps for download, including this oblique view of the Willamette River in postcard and poster formats.