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 waterbodies data used in the resistance surface. To see actual resistance values assigned to the waterbody classes in this raster when the resistance surface is compiled, see the associated spreadsheet of resistance surface data sources and resistance values.

The waterbodies resistance layer was developed from the USGS’ National Hydrography Dataset (NHD) (USGS 2013), which maps the surface waters of the United States. Our model operates under the assumption that large waterbodies are significant impediments that are not readily utilized by martens moving across the landscape. As such, waterbodies in the NHDWaterbody feature dataset with the classification of LakePond and Reservoir are all assigned a restrictive resistance value of 500 per pixel in our derived ResistanceData_Waterbodies raster.

Development Process

To develop our waterbodies data layer, we used an NHD feature dataset available in the OR and CA NHD geodatabases called NHDWaterbody, which contains features representing areal NHD hydrographic waterbody features in the NHD model. Waterbody features from this dataset with the feature types LakePond, Reservoir, Estuary, and SwampMarsh were extracted from each state dataset. These datasets were then converted to rasters, mosaicked, and "clipped" to our Modeling Extent using Raster Calculator.

We included the Estuary and SwampMarsh feature types in this dataset to maintain flexibility as our model was being conceptualized early in the project. Ultimately, the SwampMarsh and Estuary feature types were not included in the final resistance surface. For clarity, estuaries are handled in a separate, manually developed raster (ResistanceData_BaysEstuaries) that perfectly integrates with the forested and non-forested land cover datasets that were derived from the GNN Structure forest model.

Additional context and information on the development of this data layer can be found by reviewing the resistance surface data and accompanying metadata, as well as the corresponding spreadsheet of resistance surface data sources and resistance values. For additional information on our broader connectivity analysis, please see the report developed for this project, especially the sections titled Data Layers and Mapping Landscape Resistance to Movement, which describe the process and logic used in developing these data layers, compiling them into a resistance surface, and determining resistance values.