Event Title

Changes in Western US Streamflow and Climate Regimes during 1912 and 2010

Presenter Information

Margaret Matter

Location

ECC 216

Event Website

http://water.usu.edu/

Start Date

4-3-2012 3:30 PM

End Date

4-3-2012 3:35 PM

Description

We applied quantile regression to streamflow data from gages in relatively unimpaired river basins and indices for three major modes of climate variability in the Western US for 1912-2010. Our objectives were to determine where changes occurred in the distributions of streamflow and climate indices, and to associate the changes in streamflow and climate. Quantile regression results revealed significant changes during the period of record in mean annual streamflow and the index for and annual transition in standardized sea level pressure at Darwin, Australia. Streamflow changed significantly (p ? 0.05) at 57% of the gages. Upper quantiles of flow increased at gages in states along the West Coast and in the Great Basin, while lower quantiles of flow decreased at gages in states of the Colorado Plateau. During the same time period, the index for and annual transition in Darwin SLP (DSLP and t-DSLP, respectively) also changed significantly. In 77% of the cases where high flows increased, the flows correlated most frequently with DSLP and t-DSLP for June-August. In the remaining 23% of the cases, the quantiles of flow were not correlated with any of the climate indices used in this study. In all cases where the low flows decreased, the lower quantiles of flow correlated with DSLP for June-August as well as for June-October and DecemberFebruary, all of which changed significantly since 1912. The results show that significant changes in Western US streamflow, and DSLP and t-DSLP, the ENSO variables, occurred mainly in the upper and lower quantiles of the distributions between 1912 and 2010. Gages which exhibited increases in high flows were geographically distinct from those where low flows decreased. Eighty-two percent of quantiles of flow which changed significantly during the period of record were correlated with DSLP and/ or t-DSLP. The influence of changes in ENSO on streamflow, however, must be interpreted within the context of modulating effects of AMO, PDO, and time which were also correlated with flows that changed. While climate explains much of the variance in streamflow, factors in addition to the climate indices used in this study also contributed to changes in streamflow regime in the Western US since 1912.

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Apr 3rd, 3:30 PM Apr 3rd, 3:35 PM

Changes in Western US Streamflow and Climate Regimes during 1912 and 2010

ECC 216

We applied quantile regression to streamflow data from gages in relatively unimpaired river basins and indices for three major modes of climate variability in the Western US for 1912-2010. Our objectives were to determine where changes occurred in the distributions of streamflow and climate indices, and to associate the changes in streamflow and climate. Quantile regression results revealed significant changes during the period of record in mean annual streamflow and the index for and annual transition in standardized sea level pressure at Darwin, Australia. Streamflow changed significantly (p ? 0.05) at 57% of the gages. Upper quantiles of flow increased at gages in states along the West Coast and in the Great Basin, while lower quantiles of flow decreased at gages in states of the Colorado Plateau. During the same time period, the index for and annual transition in Darwin SLP (DSLP and t-DSLP, respectively) also changed significantly. In 77% of the cases where high flows increased, the flows correlated most frequently with DSLP and t-DSLP for June-August. In the remaining 23% of the cases, the quantiles of flow were not correlated with any of the climate indices used in this study. In all cases where the low flows decreased, the lower quantiles of flow correlated with DSLP for June-August as well as for June-October and DecemberFebruary, all of which changed significantly since 1912. The results show that significant changes in Western US streamflow, and DSLP and t-DSLP, the ENSO variables, occurred mainly in the upper and lower quantiles of the distributions between 1912 and 2010. Gages which exhibited increases in high flows were geographically distinct from those where low flows decreased. Eighty-two percent of quantiles of flow which changed significantly during the period of record were correlated with DSLP and/ or t-DSLP. The influence of changes in ENSO on streamflow, however, must be interpreted within the context of modulating effects of AMO, PDO, and time which were also correlated with flows that changed. While climate explains much of the variance in streamflow, factors in addition to the climate indices used in this study also contributed to changes in streamflow regime in the Western US since 1912.

https://digitalcommons.usu.edu/runoff/2012/Posters/30