Simulating climate variability impacts on streamflow of the layawan river watershed using the swat model

Abstract

© 2020, Asian Association for Agricultural Engineering. All rights reserved. This study was conducted to simulate and assess the impact of climate variability on streamflow of a watershed in Southern Philippines using the Soil and Water Assessment Tool (SWAT) model. The SWAT model was calibrated and validated using monthly observed streamflow data of Layawan River. The SWAT model performed satisfactorily with R2=0.73, Nash-Sutcliffe efficiency (NSE)=0.59, RSR=0.64 and PBIAS=21.18% during calibration, and R2=0.60, NSE=0.56, RSR=0.66 and PBIAS=7.01% during validation. A total of 15 climate variability scenarios were formulated to mimic actual El Niño or La Niña occurrences based on observed weather station data nearest to the watershed. Extremely low and extremely high streamflow values were predicted under very strong El Niño and moderate La Niña scenarios, respectively. The decrease in streamflow under very strong El Niño reached 57.1% while the increase in streamflow under moderate La Niña went as high as 400% with respect to the baseline conditions. Results showed that rainfall had more influence on streamflow of the Layawan River watershed than temperature. The streamflow simulation results under climate variability scenarios also revealed that the after-effects of extreme El Niño events could last for two to three months after it has ceased and yet could continue to behave abnormally depending on the succeeding climatic condition. This study provided useful information for the development of extreme climate variability mitigation and adaptation strategies and water resources management for crop production in Layawan River basin and other regions in the Philippines.

Source or Periodical Title

International Agricultural Engineering Journal

ISSN

8582114

Page

2023-09-01

Document Type

Article

Subject

Climate variability, El Niño, La Niña, Streamflow simulation, SWAT model

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