Assessment On Long-term Fluctuations Of Runoff And Its Climate Driving Factors

Abstract

The Jing River is the largest tributary of the Wei River in northwestern China. Studying the long-term characteristics of its runoff is of significance to water resources planning and management as well as the design of hydraulic engineering activities at the local and Wei River basin scales in the present and future. Several methods were utilized in this study to investigate the long-term fluctuations in runoff for the Jing River, including continuous wavelet analysis, the Hilbert Huang transform and correlational analysis. Furthermore, the responses of runoff to various climatic and meteorological factors including precipitation, evaporation, solar activity and the El Nino-Southern Oscillation (ENSO) phenomenon were also studied. The results indicate that the river's annual runoff exhibits multi-timescale fluctuation characteristics with a cycle of 2-4, 6-8 and 22-24 years, where the 22-24 year cycle oscillation being the first main period. The primary drivers of runoff fluctuations are climate changes, with precipitation the main driver of the 2-4 year's fluctuation and solar activity & ENSO dominant for the 22-24 year period. Though runoff exhibits a significant response to the ENSO phenomenon, it lags behind ENSO by 5 years. This delay may occur as a result of Pacific-Asian atmospheric teleconnection transmitting some information on ENSO to Asia.