2.5 Metric Evaluation
We evaluated the use of geochemical (σg) and microbial (σm) connectivity strength metrics using several approaches. First, we compared σg and σmagainst the conservative tracer (NaCl) injection results including a binary assessment of arrival or no response of the injected tracer. At sites with arrival, we calculated Pearson correlation coefficients between σg and σm and time to peak of the tracer breakthrough curve (i.e., advective time). To compare connectivity strength metrics against the relative stage dataset, we calculated durations of connectivity between source and each target site. For relative stage, connectivity duration was defined as the percent of the study period when Inflow stage was above the determined inflection point in source-target stage relationships as described in section 2.4. For σg and σm, connectivity duration was defined as the percent of the study period in which σg and σm were above 0.5. Pearson correlation coefficients were calculated to compare whether metrics performed similarly across all sites. To explore the sensitivity of results to a chosen connectivity strength threshold, we also calculated the daily number of connected sites using thresholds ranging from the 10th to 90th percentile of σm (0.24 to 0.79).