NPS Stream Navigability Model

This code release fits a Bayesian logistic regression model to predict the probability that stream segments flowing through
National Park lands in Alaska are considered navigable, based on slope (drop in elevation / segment length) and
Strahler stream order, an ordinal metric with values ranging from 1-6. The model uses existing navigability determinations for
a subset of stream segments, which were assessed during site visits by Bureau of Land Management peronnel. It then generates
predicted navigability probabilities for all stream segments in the input dataset, including those without pre-existing determinations.
This code release implements the model, but does not assess model predictive performance, which will be addressed in a forthcoming
manuscript via cross-validation.