Fig 1.
A thermal regime model fit to observed data.
This example uses data from USGS site 11390500 (Sacramento River below Wilkins Slough near Grimes, CA). Cluster analysis is based on annual mean, amplitude, and phase metrics for each thermal regime model. Amplitude and phase are analogous to annual maximum and day of annual maximum metrics. Figure adapted with permission from Maheu et al. [31]: Fig 1.
Fig 2.
Histograms of residual standard error, grouped by thermal class.
Fig 3.
Results of the clustering analysis.
a) California’s thermal regimes were grouped into five clusters, with the centroid of each cluster marked by relatively larger symbols designated for each cluster. The inflection points at k = 5 in the b) elbow and c) silhouette analyses further support the selected groupings.
Fig 4.
Thermal regime models and metrics.
a) Classified models and box plots of b) annual mean, c) day of annual maximum, and d) annual amplitude; based on Maheu et al. [31]: Fig 3, with permission. Thermal regimes were characterized based on their mean annual maximum (warm, cool, or cold) and relative annual variability. The number of members for each class (n) is as follows: Stable warm (n = 1), variable warm (n = 30), variable cool (n = 12), stable cool (n = 32), stable cold (n = 2).
Table 1.
A summary of thermal regime classes.
Thermal regime class summaries include the number of members (n); average annual maximum and mean water temperatures; and day of annual maximum.
Fig 5.
Map of classified thermal regimes and dams located upstream of study sites in California.
Dotted lines show the borders of California’s hydrologic regions as defined by the state Department of Water Resources.
Fig 6.
Panels of thermal regimes below a) Shasta, b) Lewiston, c) New Melones, d) Friant, and e) Success dams. See Fig 5 for location of each inset map in the study area.
Table 2.
Thermal regimes in each hydrologic region.
Hydrologic regions are defined the California Department of Water Resources; the Central Coast, South Coast, and Colorado River are not included as no study sites were located in those regions.
Fig 7.
Histogram of thermal regime location relative to nearest upstream dam.