Streamflow Permanence Class (SPC) rasters (PROSPER)

Streamflow Permanence Class (SPC) rasters represent the classification of the raw streamflow permanence probabilities produced by the PRObability of Streamflow PERmanence (PROSPER) model into categorical wet and dry classes, annually for years 2004 through 2016, and overall mean. Raw probabilities were classified into a -5 (dry) to +5 (wet) scale based on the spatially variable threshold (i.e., value that predicts the wet/dry break point) and confidence interval rasters. In general, the farther a raw probability value is from the threshold value for a given pixel, the farther the categorical value is from zero for that pixel. For example, a raw probability that is less than the threshold value minus the critical value for the 95-percent confidence interval for a given pixel would be assigned an SPC value of -5. Conversely, if a raw probability is greater than the threshold value plus the critical value associated with the 95-percent confidence interval for a given pixel, it would be assigned an SPC value of 5. The PROSPER model is a GIS raster-based empirical model of probabilistic predictions of a stream channel having year-round flow for any unregulated and minimally-impaired stream channel in the Pacific Northwest region, U.S. The model provides predictions of annual streamflow permanence probabilities at a 30-m spatial resolution based on monthly or annually updated values of climatic conditions and static physiographic variables associated with the upstream basin. Predictions correspond to pixels on the channel network consistent with the medium resolution National Hydrography Dataset channel network stream grid.