|
|||||
|
|
Impacts of El Niño–southern oscillation on global runoff: Characteristic signatures and potential mechanisms |
|
| Authors: | Yuanyuan You Jianyu Liu Yongqiang Zhang Hylke E Beck Xihui Gu Dongdong Kong |
| Institution: | 1. Laboratory of Critical Zone Evolution, School of Geography and Information Engineering, China University of Geosciences, Wuhan, China
State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan, China State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing Hydraulic Research Institute, Nanjing, China;2. Laboratory of Critical Zone Evolution, School of Geography and Information Engineering, China University of Geosciences, Wuhan, China;3. Key Lab of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China;4. Directorate-General Joint Research Centre, European Commission, Ispra (VA), Italy;5. Department of Atmospheric Science, School of Environmental Studies, China University of Geosciences, Wuhan, China |
| Abstract: | Runoff signatures, including low flow, high flow, mean flow and flow variability, have important implications on the environment and society, predominantly through drought, flooding and water resources. Yet, the response of runoff signatures has not been previously investigated at the global scale, and the influencing mechanisms are largely unclear. Hence, this study makes a global assessment of runoff signature responses to the El Niño and La Niña phases using daily streamflow observations from 8217 gauging stations during 1960–2015. Based on the Granger causality test, we found that ~15% of the hydrological stations of multiple runoff signatures show a significant causal relationship with El Niño–southern oscillation (ENSO). The quantiles of all runoff signatures were larger during the El Niño phase than during the La Niña phase, implying that the entire flow distribution tends to shift upward during El Niño and downward during La Niña. In addition, El Niño has different effects on low and high flows: it tends to increase the low and mean flow signatures but reduces the high flow and flow variability signatures. In contrast, La Niña generally reduces all runoff signatures. We highlight that the impacts of ENSO on streamflow signatures are manifested by its effects on precipitation (P), potential evaporation (PET) and leaf area index (LAI) through ENSO-induced atmospheric circulation changes. Overall, our study provides a comprehensive picture of runoff signature responses to ENSO, with valuable insights for water resources management and flood and drought disaster mitigation. |
| Keywords: | atmosphere circulation characteristic signatures El Niño–southern oscillation potential mechanisms runoff sensitivity analysis |