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Open-File Report O-12-07, Lidar data and landslide inventory maps of the North Fork Siuslaw River and Big Elk Creek watersheds, Lane, Lincoln, and Benton Counties, Oregon, by William J. Burns, Serin Duplantis, Cullen B. Jones, and John T. English. 15 p. PDF report plus four appendices, 2 PDF thematic map plates, two Esri ArcGIS v. 10 geodatabases.

Order publication CD-ROM, $15, from Nature of the Northwest.

Deliverables of this study include the following:

Executive Summary

In August 2011 the Oregon Department of Geology and Mineral Industries (DOGAMI) contracted with the United States Environmental Protection Agency (US EPA) (Order EP-11-7-000174) to collect lidar (light detection and ranging) data for seven watersheds in the Oregon Coast Range Mountains and to perform regional landslide inventory mapping of two of these watersheds.

The purpose of this study was to assist US EPA and the Oregon Department of Environmental Quality (DEQ) in understanding potential landslide sources and to improve ability of these agencies to identify other potential sources of stream sedimentation and warming by using high-resolution lidar data. Lidar collection and landslide mapping were undertaken because US EPA and DEQ are concerned about excessive sedimentation, turbid waters, and stream warming in watersheds in Coast Range. Some common sources for sedimentation and stream warming include landslides, unmaintained roads, lack of vegetation, and degraded stream banks. One major obstacle to correctly assigning sources is the lack of accurate topographic data and landslide maps. Recent studies have shown that the use of light detection and ranging (lidar) data to map landslides greatly improves the accuracy of the maps.

Two main tasks were required to accomplish the purpose: 1) lidar data acquisition, processing, quality control review, and data/report delivery and 2) landslide mapping and data delivery.

Task 1 included acquiring new lidar data and combining these data with existing lidar data to cover the seven watersheds. Examples of methods that can be used to identify both landslide and nonlandslide sources of sediment and stream warming are described in this report.

Task 2 included creating a landslide inventory geodatabase following the protocol of Burns and Madin (2009) (see Appendix A of this report) and providing map imagery. The data in this inventory are much more complete than those in previous inventories. For example, previous inventories, which include seven studies covering the North Fork Siuslaw and Big Elk Creek watersheds, locate a total of 261 landslide deposits, whereas the current study locates 2,840 landslide deposits in these same two watersheds.

Reference:
Burns, W. J., and Madin, I. P., 2009, Landslide protocol for inventory mapping of landslide deposits from light detection and ranging (lidar) imagery: Oregon Department of Geology and Mineral Industries Special Paper 42, 30 p., geodatabase template.

 

Plate 1. Lidar data and landslide inventory map of the North Fork Siuslaw River watershed, Lane County, Oregon

Plate 1, North Fork Siuslaw watershed

 

Plate 2. Lidar data and landslide inventory map of the Big Elk Creek watershed, Lincoln and Benton Counties, Oregon

Plate 2, Big Elk Creek watershed