水文变异对水库汛期分期及汛限水位确定的影响

为科学探讨水文变异对水库汛期分期及汛限水位的影响,基于广西澄碧河水库53年径流数据,采用Mann-kendall、滑动T和Morlet小波等分析水文变异情况并确定突变年,应用集对分析法分别对变异前后的水库汛期进行分期,并结合调洪演算推求和比较水文变异前后的汛限水位。结果表明:径流序列呈现下降趋势,并存在19年的主周期,突变年为1990年。水文变异对水库汛期分期结果有一定影响,主要表现为缩短了前过渡期历时,延长主汛期历时。前汛期汛限水位可调控范围变异前为185~187 m,变异后为185~187.97 m,水文变异使前汛期汛限水位调控上限增加0.97 m,而后汛期变异前为185~188 m,变异后为185~187 m,水文变异使后汛期汛限水位调控上限减少1 m,可见水文变异主要影响着前后汛期汛限水位调控的上限,主汛期无明显变化。

Influence from hydrological variation on reservoir flood season division and determination of its flood-limited water level

In order to scientifically explore the influence from the hydrological variation on the reservoir flood season division and its flood-limited water level, the hydrological variation is analyzed, and then the mutation year is determined by means of MannKendall, Slide T and Morlet wavelet, etc. in accordance with the runoff data of 53 years from Chengbihe Reservoir in Guangxi. Moreover, the reservoir flood seasons before and after the variation are divided with the method of set pair analysis, while the flood-limited water levels before and after the variationare compared in combination with the sum derived the relevant flood routing as well. The result shows that the runoffseries presents a declined trend with a major cycle of 19 years and the mutation year of 1990. The hydrological variation has a certain influence on the result of the flood season division for the reservoir, of which the main expressions are shortening the duration of the pre-transition period and prolonging the duration of the main flood season. The regulable range of the pre-flood season flood-limited water level is 185 ~ 187 m before the variation, while it is 185 187. 97 m after the variation, thus the hydrological variation makes the regulable upper limit of the pre-flood season flood-limited water level increased by 0. 97 m. Moreover, the regulable range of the post-flood season flood-limited water level is 185 ~ 188 m before the variation, while it is 185 ~ 187 m after the variation, thus the hydrological variation makes the regulable upper limit of the post-flood season flood-limited water level decreased by 1. 0 m. It demonstrates that the hydrological variation mainly affects the regulable upper limits of both the pre-flood season flood-limited water level and the post-flood season flood-limited water level, thus no obvious changes are there during the main flood season.