Trend, periodicity and abrupt change in streamflow of the East River, the Pearl River basin

Abstract

Abstract:The East River in the Pearl River basin, China, plays a vital role in the water supply for mega-cities within and in the vicinity of the Pearl River Delta. Knowledge of statistical variability of streamflow is therefore important for water resources management in the basin. This study analyzed streamflow from four hydrological stations on the East River for a period of 1951-2009, using ensemble empirical mode decomposition (EEMD), continuous wavelet transform (CWT) technique, scanning t and F tests. Results indicated increasing/ decreasing streamflow in the East River basin before/after the 1980s. After the early 1970s, the high/low flow components were decreasing/increasing. CWT-based analysis demonstrates a significant impact of water reservoirs on the periodicity of streamflow. Scanning t and F test indicates that significantly abrupt changes in streamflow are largely influenced by both water reservoirs construction and precipitation changes. Thus, changes of streamflow, which are reflected by variations of trend, periodicity and abrupt change, are due to both water reservoir construction and precipitation changes. Further, the changes of volume of streamflow in the East River are in good agreement with precipitation changes.

Evaluation of flood frequency under non-stationarity resulting from climate indices and reservoir indices in the East River basin, China

“…This phenomenon can be attributed to different distances between hydrological stations and water reservoirs. The influence of water reservoirs on flood regimes diminishes with the lengthening of the distances between water reservoirs and hydrological stations, which has been corroborated by previous researches (Zhou et al, 2012;Zhang et al, 2014).…”

“…3 that relations between annual maximum stream-flow and climate indices at these four stations are not statistically significant, which can be attributed to the regulations of water reservoirs on flood processes of the East River basin. The influence of reservoir-induced alterations of the hydrological processes has been well documented (Zhou et al, 2012;Zhang et al, 2014). The regulations of water reservoirs violated relations between annual maximum stream-flow changes and climate indices.…”

“…Besides, intensifying human activities, such as urbanization (Villarini et al, 2009) and construction of water reservoirs are also being observed (Zhang et al, 2009a(Zhang et al, , 2009b. Zhang et al (2014) found increasing/decreasing stream-flow in the East River basin before/after the 1980s. All these factors combine to alter hydrological processes and trigger non-stationarity of hydrological extremes, such as annual peak flood regimes (e.g.…”

Hydrological alterations from water infrastructure development in the Mekong floodplains

“…Dam effects on the main rivers in the United States, for instance, were well documented by Graf (2006) and Fitzhugh and Vogel (2010). Zhang et al (2014) carried out a historical data analysis to show the reservoir-induced hydrological alterations of flows in the East River (Pearl River basin, China). There are also other examples from around the world such as the Ebro River basin in Spain (Batalla et al, 2004), the Murray-Darling basin in Australia (Kingsford, 2000) or the Medjerda River basin in Tunisia (Zahar et al, 2008) which demonstrated the impacts of dam construction on water systems.…”

Intra-annual Distribution of Streamflow and Individual Impacts of Climate Change and Human Activities in the Dongijang River Basin, China

“…The method has been considered to be appropriate for climate change analysis and has been commonly used for analysis of hydrological time series Farahani and Khalili 2013;Zhang et al 2014). The Mann-Kendall statistic S is defined as:…”