Rivers (resistance surface component) - A landscape connectivity analysis for the coastal marten (Martes caurina humboldtensis)

The resistance surface that formed the basis of our coastal marten connectivity model is comprised of several data layers that represent forested and non-forested land cover, waterbodies, rivers, roads, and serpentine soils.

This dataset contains the rivers data used in the resistance surface. To see actual resistance values assigned to the river classes in this raster when the resistance surface is compiled, see the associated spreadsheet of resistance surface data sources and resistance values.

The rivers resistance layer was developed from the USGS’ National Hydrography Dataset (NHD) (USGS 2013), which maps the surface waters of the United States. The NHD within our modeling extent included a derived attribute called Strahler Stream Order (Strahler 1952) , which is a hierarchical classification of streams moving from the headwaters to the ocean (for a succinct explanation of this attribute, see: https://usgs-mrs.cr.usgs.gov/NHDHelp/WebHelp/NHD_Help/Introduction_to_the_NHD/Feature_Attribution/Stream_Order.htm). Using these stream orders allows us to identify and apply relative weights to the major rivers and their corresponding reaches across the landscape (e.g. Klamath, Rogue, Coquille, and Umpqua Rivers as 9th order streams, and the Eel, Smith, Siuslaw, and Alsea Rivers as 8th order streams). Based on marten dispersal observations and our estimation of how challenging these rivers and creeks may be for martens to cross, we created a resistance layer incorporating all stream lines between stream order 4 (e.g. Redwood Creek) and 10 (the Columbia River), with increasing resistance as the order increases.

Rivers and roads were represented as linear features a single pixel 30m wide. Because many of these features were modeled as representing significant barriers to movement by martens, we took care to minimize the occurrence of any breaks in these linear features that would encourage LCPs to pass through them. In many instances, roads and rivers are in fact wider than 30m, and in these cases the pixels were classified by the relevant surrounding land cover type (OGSI or ESLF).

To develop our rivers data layer, we used an NHD feature dataset available in the OR and CA NHD geodatabases called NHDFlowline, which is the fundamental flow network of the NHD model, consisting predominantly of stream/river and artificial path vector features. The NHD geodatabases that house this feature dataset also contain a complementary table of additional attributes that are derived from NHDFlowline data. This "Value Added Attributes" table is called NHDFlowlineVAA, and it contains an attribute called StreamOrder which provides the Strahler stream order number for each feature (Strahler stream order is referenced in the preceding paragraphs).

This is an abbreviated and incomplete description of the dataset. Please refer to the spatial metadata for a more thorough description of the methods used to produce this dataset, and a discussion of any assumptions or caveats that should be taken into consideration.