ENSO-Related Variability of Monthly Mean Streamflow for the Jiulong River in Fujian Province, Southeast China

Several studies have shown significant relationships between the El Nino-Southern Oscillation (ENSO) and stream flows at global, regional and local scales. This paper presents an overview of the relationship between the ENSO and mean-monthly stream flows (1967-2008) of five hydrological stations in the Jiulong River in Fujian Province, Southeast China. Results show that in the 24-month life cycle of warm phase of ENSO (El Nino), it tends to have lower stream flows in the first spring (from March through May), and higher stream flows in the first winter (from December through February) and the second spring. During the period of cold phase of ENSO (La Nina), it tends to have lower stream flows in the first winter and the second spring. Meanwhile, a lag correlation between the mean-monthly stream flows and surface sea temperature anomalies is also examined. Results show that, during El Nino events, stream flows have strong lag correlations from zero to six months with surface sea temperature anomalies (r = 0.250-0.576 at the 99% level, the strongest ones are one to three months), and weak lag correlations from three to four months in the period of La Nina events (r = 0.238-0.289 at the 99%level) for the Jiulong River. The likely reason for the difference is that the typical El Nino events persist for some 18months, while a La Nina condition can last up to two years or more, so an further study finds that, during period of long LaNina events (longer than two years), the stream flow responses to SSTA lags by two to five months, with stronger correlations between 0.339-0.559 at the 99% level. These conclusions are invaluable for management of water resources, particularly in the dry seasons of the watershed.