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Open AccessArticle

Streamflow variability over the Period of 1990–2014 in Mahaweli River basin, Sri Lanka and Its Possible Mechanisms

by Sherly Shelton 1,2 and Zhaohui Lin 1,2,3,*
1
International Center for Climate and Environment Sciences, Institute of Atmospheric Physics, Chinese Academy of Sciences, P.O. Box 9804, Beijing 100029, China
2
University of Chinese Academy of Sciences, Beijing 100049, China
3
Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing 210044, China
*
Author to whom correspondence should be addressed.
Water 2019, 11(12), 2485; https://doi.org/10.3390/w11122485
Received: 7 October 2019 / Revised: 15 November 2019 / Accepted: 19 November 2019 / Published: 25 November 2019
(This article belongs to the Section Hydrology)
This study investigates the variation of seasonal streamflow and streamflow extremes in five catchments of the Mahaweli River Basin (MRB) Sri Lanka from 1990 to 2014, and the relationship between streamflow and seasonal rainfall in each catchment is then examined. Furthermore, the influence of Indian Ocean Dipole (IOD) and El Nino and Southern Oscillation (ENSO) on the seasonal rainfall and streamflow in the upper (UMRB) and lower reaches (LMRB) of MRB are explored. It’s found that the rainfall amount in southwest monsoon (SWM) season contributes 29.7% out of annual total rainfall in the UMRB, while the LMRB records 41% of the total rainfall during the northeast monsoon (NEM) season. The maximum streamflow of upper (lower) Mahaweli catchments is observed in the SWM (NEM) season. Catchments in the UMRB (LMRB) recorded strong interannual variability of seasonal overall flow (Q50), Maximum 10-day, and 30-day flows during the SWM (NEM) season. It’s further revealed that the catchment streamflow in the UMRB is closely correlated with the SWM rainfall in the interannual time scale, while streamflow of catchments in the LMRB is closely associated with the NEM rainfall. The effects of ENSO and IOD on streamflow are consistent with their impacts on rainfall for all catchments in MRB, with strong seasonal dependent. These suggested that the sea surface temperature anomalies in the both Indian Ocean and tropical Pacific Ocean are important factors affecting the streamflow variability in the MRB, especially during the SWM season.
Keywords: Streamflow variability; Hydrological extreme; seasonal rainfall, Mahaweli River Basin; ENSO; Indian Ocean Dipole Streamflow variability; Hydrological extreme; seasonal rainfall, Mahaweli River Basin; ENSO; Indian Ocean Dipole
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MDPI and ACS Style

Shelton, S.; Lin, Z. Streamflow variability over the Period of 1990–2014 in Mahaweli River basin, Sri Lanka and Its Possible Mechanisms. Water 2019, 11, 2485.

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