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| DOI：10.13522/j.cnki.ggps.2022247 |
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| Runoff Variation and Its Effect on Statistical Characteristics and Frequency of Runoff in the Upper Reaches of Heihe River Basin |
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XI Haichao, XIE Yangyang, LIU Saiyan, HUANG Chengjian, SHEN Teng, ZHANG Qin
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1. College of Hydraulic Science and Engineering, Yangzhou University, Yangzhou 225009, China;
2. Modern Rural Water Conservancy Research Institute, Yangzhou University, Yangzhou 225009, China
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| Abstract: |
| 【Objective】Statistical characteristics and frequency of runoff is crucial for water resources planning and water resource project construction, especially when runoff in watersheds shows significant variation due to environmental changes. Taking upper reach of the Heihe River basin as an example, this paper examines the impact of runoff variation on statistical characteristics and frequency of the runoff analysis.【Method】Annual runoff and annual maximum flooding flow measured from the reach were used in our study. Two types of analysis windows, the fixed-point variable-width window (Type A window) and the variable-point fixed-width window (Type B window), were used to extract the runoff sequences (window sequences) for analysis. The P-Ш type curves were utilized to analyze the statistical characteristics of the window series, from which we calculated the runoff design values. The trends and discontinuity in the window series were identified using the linear trend analysis, MMK trend test, and heuristic segmentation method.【Result】① The estimated annual runoff parameters (Ex) showed a significant increasing trend and abrupt changes in both Type A and Type B window analyses. The coefficient of variation (Cv) showed a significant increasing trend in Type A window analysis and abrupt changes in Type B window analysis. The coefficient of skewness (Cs) showed abrupt changes in Type B window analysis. Design values for different frequencies of the annual runoff showed a significant increasing trend and abrupt changes in both types of windows. ② The estimated parameters in the annual maximum showed abrupt changes in Type A window analysis, while the Ex showed abrupt changes in Type B window analysis. Cs showed a significant increasing trend and abrupt changes in Type B window analysis. Design values for different frequencies of the annual maximum flooding did not identify any significant increasing trend in Type A window analysis but showed sudden changes. In Type B window analysis, there was a significant increasing trend and abrupt changes.【Conclusion】 Analyzing runoff processes should use long sequences to capture the whole spectrum of the runoff pattern. Using long runoff series can mitigate the influence of extreme runoffs on statistical characteristics and frequency of runoff analysis. |
| Key words: time-varying characteristics; frequency analysis; trend test; heuristic segmentation method; Heihe River Basin |
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