Climate Variability And Changes In Streamflow And Precipitation Extremes

Ramesh Teegavarapu

Thursday 2 july 2015

8:50 - 9:10h at Europe 1 (level 0)

Themes: (T) Special session, (ST) Adaptation to global changes in water resources management

Parallel session: 10J. Special session - Adaptation to Global Changes in Water Resources Management

Evaluation of the influences of coupled oceanic-atmospheric oscillations affecting streamflow and precipitation extremes and characteristics at a regional scale is the focus of this study. Two oscillations considered in this study and they are: Atlantic multidecadal oscillation (AMO), El Nino southern oscillation (ENSO). The study area is the South-Atlantic Gulf region of the U.S. Several standard low flow indices, streamflow deficit durations, temporal occurrences of these deficits and other characteristics of low flow extremes during two different phases of these oscillations are evaluated. Higher end streamflow and precipitation extremes are also evaluated using several extreme indices. Variability of streamflows and precipitation extremes are evaluated using a joint probability approach. Long-term precipitation and streamflow data from 45 Hydro-Climatic Data Network (HCDN) basins that are least distributed by anthropogenic influences are used for evaluation. Parametric hypothesis tests are used to evaluate statistically significant changes in the characteristics of low and high flows and precipitation extremes. Inferences about influences of oscillations on droughts/floods from the results of statistical analysis and possible physical basis explanations are expected outcomes of this study. Evaluation and understanding of changes in frequency and intensity (severity) of droughts as well as floods conditioned on precipitation extremes and their links to climate variability are critical for basin scale water resources management. Spatially varying (uniform and non-uniform influences of oscillations on streamflow and precipitation extremes are noted. Regional climatology defines the extent of these influences in the region.