Renmin Zhujiang (Jan 2024)
Characteristics of Extreme Runoff in Beijiang River Basin during Dry Season from 1954 to 2020
Abstract
This paper utilized the daily average flow data from 1954 to 2020 at the Shijiao control station within the Beijiang River Basin. It also employed indicators of hydrological alteration (IHA), heuristic segmentation algorithms, Mann-Kendall trend test, and wavelet analysis to examine the distribution characteristics, trends, variability, and cycle of extreme runoff in the Beijiang River Basin during dry season across various time scales. The results are as follows: ① The extreme runoff in the Beijiang River Basin during dry season predominantly occurs in the middle and later stages of the dry season, with January and February of the following year having frequent occurrences of extreme runoff. If a short-term extreme runoff during dry season is observed, there is a high probability of exceeding 64% that a long-term extreme runoff during dry season will emerge. ② The variability of the three extreme indicators for the average flow, annual minimum 1-day average flow, and annual minimum 90-day average flow in the Beijiang River Basin during dry season is not significant. In contrast, the variability of the extreme indicators for the annual minimum 3-day average flow, annual minimum 7-day average flow, and annual minimum 30-day average flow is significant, with all significant change points occurring in 1970. ③ The extreme runoff indicators for the Beijiang River Basin during dry season are all trending upwards. Specifically, the annual minimum 7-day average flow, annual minimum 30-day average flow, and annual minimum 90-day average flow are increasing significantly at an annual rate of 1.12, 1.60, and 1.87 m3/s, respectively. ④ According to the variability and trend of extreme runoff indicators during dry season across different time scales, the construction of water conservancy projects has a significant impact on the mid-time scale runoff during dry season. ⑤ The extreme runoff indicators for the Beijiang River Basin during dry season exhibit 3–4 distinct oscillation cycles. These can be roughly divided into long oscillation cycles on a large scale of 22–34 years, middle oscillation cycles on a mid-scale of 16–20 years, and short oscillation cycles on a small scale of 7–11 years, with a high degree of similarity in their oscillation cycles.
