广东省主要河流最低通航水位变异分析

近些年剧烈的气候变化和高强度的人类活动,使得基于一致性的传统最低通航水位设计方法不再满足航运设计需求。本文选取广东省东江、西江、北江、韩江四个主要河流为研究对象,采用水文变异诊断系统对其年平均水位序列进行诊断分析,发现四大河流的控制出口站年平均水位序列均发生了中变异或强变异。针对变化环境下的水位资料,用综合历时曲线法对变异前后和整体的日水位序列进行分段计算,比较各站整体与变异后段序列设计水位值,结果显示潮安站偏大超过30%,其他站偏小超过30%;对保证率频率法中的年通航特征水位序列进行变异诊断,发现其也发生了不同形式和不同程度的变异,从而揭示了这两种传统计算方法在"非一致性"水位序列下存在的问题。

Variation analysis of lowest navigable water levels in major rivers in Guangdong province

Due to intense interference from climate change and human activities in recent years, the traditional consistent design methods for calculation of design lowest navigable water level no longer meet the demands. In this study, a hydrological variation diagnosis system has been applied to analysis of annual mean water level series for four major rivers in Guangdong: East River, West River, North River, and Hanjiang River. Results show that moderate or strong variations in river level have been detected at the outlet control stations of these rivers. Then, we applied a synthetic duration curve method to the series of river level under the changing environments, using two separate daily water level sub-series segmented at the change point, and compared the calculations of design lowest navigable water level based on the pro- and post-changepoint sub-series and the whole series. The results indicate that climate change has caused an increase of more than 30% in navigation depth at the Chaoan station while a decrease of more than 30% at other stations. A frequency guarantee rate method was also adopted to diagnose the annual series of characteristic navigation levels, and this revealed change points of different forms and degrees in these series corresponding to different guarantee rates. Thus, our results show the existing problems with the two traditional methods in calculation of inconsistent water level series.