Impacts of El Nino/Southern Oscillation (ENSO) on streamflows in Nepal

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Authors

Shrestha, Archana

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University of Guelph

Abstract

This thesis investigates the impact of the El Nino/Southern Oscillation (ENSO) on mean monthly streamflows in Nepal using the Mann Whitney U test, harmonic analysis and correlation analysis. El Nino causes below-normal streamflows between July to December in western Nepal and between June and December in eastern Nepal in the El Nino years. La Nina causes above-normal streamflows in western Nepal between June and January. The multivariate ENSO index (MEI) can be used for streamflow prediction with lags of 1-2 months. El Nino has a stronger impact on streamflows than La Nina. A stronger ENSO impact in western Nepal than in eastern Nepal suggests an inverse relationship between El Nino impact and monsoon strength and a direct relationship between La Nina impact and monsoon strength. This study is the first step in understanding the ENSO-streamflow relationship in Nepal and provides important information on streamflow variability during ENSO events.

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Keywords

El Nino, Southern Oscillation, streamflows, Nepal, Mann Whitney U test

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