Fig. 5: Climate model (CESM2-LE) evaluation for non-stationarity in peakflow.

Our climate model generally captured the observed trends and non-stationarity at the reference stations in 12 of the HUC-2 regions, whereas it failed to capture observations at the non-reference stations in 15 of the HUC-2 regions. The trends (Panel a) and KPSS non-stationarity test (Panel b) were evaluated using 90-member ensemble CESM2-LE data; and their spread, including the 5^th, 25^th, 50^th, 75^th, and 95^th percentiles are represented here using a box plot. Additionally, only the results from the first ensemble are also shown. The reference stations include both the HCDN and GAGES-II reference stations, and the non-reference stations include the GAGES-II non-reference and other USGS stations (c.f., Table 1, and Fig. 1a). The CESM2-LE data were analyzed for the 1950 to 2014 period (65 years, historical simulation). See Supplementary Fig. 11 comparing the USGS observation for the same period.