GEOGRAPHICAL RESEARCH ›› 2011, Vol. 30 ›› Issue (9): 1702-1712.doi: 10.11821/yj2011090014

• Hydrology and Water Resources • Previous Articles     Next Articles

Changing properties of low streamflow: Possible causes and implications

SUN Peng, ZHANG Qiang, CHEN Xiao-hong   

  1. Department of Water Resources and Environment, Sun Yat-sen University, Guangzhou 510275, China; Key Laboratory of Water Cycle and Water Security in Southern China, Guangdong High Education Institute, Sun Yat-sen University, Guangzhou 510275, China
  • Received:2010-11-21 Revised:2011-04-12 Online:2011-09-20 Published:2011-09-20

Abstract: In this study, 11 probability distribution functions are adopted to systematically analyze the probability behaviors of the 7-day low flow regimes (the minimum average flow for the consecutive 7 days) at six hydrological stations located in the "Five Rivers" in the Poyang Lake Basin. The L-moment technique is used to estimate the parameters of the probability functions and the Kolmogorov-Smirnov method (K-S) is accepted to evaluate the goodness-of-fit of the probability functions. Trends within the 7-day low flow series are tested using the Mann-Kendall (M-K) method. The results show that: (1) Wake distribution is the candidate distribution function with the highest goodness-of-fit in the study of the extreme flow regimes over the Poyang Lake basin; (2) The 7-day low flow is in significant decrease at Lijiadu station. The frequency of the 7-day low flow regimes tends to increase after the 1970s; The 7-day low flow at the other five stations is in an increasing trend and the probability of dry episodes is decreasing. The 7-day low flow at Hushan and Wanjiabu stations is in significant increase in the mid-1980s; Moreover, variability of the 7-day low flow at Waizhou station is the smallest, and that at Lijiadu station is the largest; (3) Precipitation changes are one of the major factors influencing the 7-day low flow changes. Hydraulic facilities are helpful to the decrease of the streamflow magnitude. Besides, forestation can flatten the variability of the 7-day low flow changes. The results of this study could be of scientific and practical merits in terms of good understanding of extreme flow changes under the influences of climate changes and human activities.

Key words: frequency analysis, probability distribution functions, extreme streamflow, Poyang Lake Basin