Watersheds

Ripple

Description:NCED researchers have worked in close collaboration with Stillwater Sciences to produce a geomorphically based fish population model for salmon. Dubbed “Ripple,” the digital terrain-based model provides estimations of fish populations throughout a watershed channel network. Ripple was released to the public in July 2008 with Coho Salmon as the modeled species. Since then, the model has been downloaded by graduate student classes and provides a rapid, spatially explicit assessment of possible factors limiting salmon populations from a minimum of data.  In the last year, NCED and Stillwater have added Spring run Chinook to the modeled species. NCED partner Stillwater Sciences has applied Ripple to investigate the effects of stream temperature and large woody debris on Coho populations in Rock Creek, Oregon. Stillwater Sciences has also used Ripple in Lagunitas Creek and Pescadero Creek, California, and in the Tonsina River of Alaska to guide field investigations.  NCED is now migrating the model to the web, which will  greatly increase its accessibility and free the model from requiring a license for ArcGIS.  
Dowload: Ripple software and documentation available here

Geonet

Geomorphologically Relevant Image Processing: Today’s high resolution topography data presents new opportunities for geomorphologic research in the area of environmental prediction and hazard assessment. To use this data for such research, NCED scientists created a new computational tool: GeoNet. GeoNet extracts channels and channel networks from high resolution digital elevation data. During the extraction process, GeoNet incorporates nonlinear filtering, for the initial preprocessing of data, and energy minimization principles, for feature extraction. The use of nonlinear filtering, with a variable diffusion coefficient, achieves noise removal (in low gradient areas) and edge enhancement (in high gradient areas, ie, feature boundaries). After this preprocessing, GeoNet extracts channels as geodesics—lines that minimize a cost function, which is based on the fundamental geomorphologic characteristics of channels, such as flow accumulation and curvature. Right now, GeoNet performs only channel extractions. However, by varying the cost function, future versions of GeoNet will allow users to select other geomorphic features of interest, such as landslides, service roads, terraces, etc. GeoNet, another tool for NCED’s toolbox, represents an example of successful, interdisciplinary collaboration among geomorphologists, mathematicians, and image processing experts.
Primary tool author: Paola Passalacqua
Resources:
Visit the GeoNet 2.0 Website for downloads, documentationa and licenseing information.