珠江流域下游1960—2019水沙异变诊断及其控制因素

为了阐明强人类活动下珠江流域下游水沙异变时间节点以及异变机制,通过对1960—2019年珠江流域下游主要水文控制站西江高要、北江石角、东江博罗,以及西江干流马口和北江干流三水站的长时序水沙数据,采用Mann-Kendall非参数秩次相关检验法、Pettitt检验法和双累积曲线,诊断了三江不同流域的水沙异变点,并阐明异变的主控因子。结果表明:(1)根据以上诊断方法,可以将水沙变化分为异变和显著变化两个层级;(2)对于流量来说,马口站流量在1986年发生显著变化,主要受气候控制; 三水站的流量在1991年发生异变,主要是由于人类挖沙导致三水剖面迅速下降,经过思贤滘的分水比增大引起了径流量异变。其他站位没有发生径流显著变化以及异变;(3)5个站位的输沙率只有石角站没有发生异变,但是在1999年发生了显著变化,主要受到上游水库的建设控制。其余4个站位的输沙率和输沙量都发生了异变,而每个站位的异变时间和原因并不相同。高要站和马口站输沙率在1999—2000年发生了异变,主控制因子为上游水库和大坝的建设。北江干流的三水站和东江博罗站输沙率分别在2003年、1988年发生异变,主要是由于上游水土保持造成的。综上,珠江流域下游的水沙异变主要受到人类活动控制,理解其异变机制对河口生态环境保护和可持续利用具有重要意义。

Abnormal Changes Diagnosis and Its Control Factors of Water and Sediment Discharge in the Lower Reaches of Pearl River Basin from 1960 to 2019

In order to clarify the time node and mechanism of water and sediment variability in the lower reaches of the Pearl River Basin under strong human activities, we diagnosed their variations using Mann-Kendall nonparametric rank correlation test, Pettitt test method and double cumulative curve methods based on the long-time series water and sediment discharge from 1960 to 2019 at Gaoyao, Shijiao, Boluo, Makou and Sanshui hydrological stations. The main control factors of the variation were also clarified. The results show that:(1)according to the three study methods, the variation of the water and sediment changes can be divided into two levels: abnormal and significant changes;(2)the water discharge of Makou station changed significantly in 1986, which was mainly controlled by climate change; it had the abnormal change in 1991 at the Sanshui station, which was caused by the rapid decline of its transect caused by human sand excavation, and the water discharge increased rapidly after the redistribution of diversion ratio of water discharges between Sanshui and Makou; there were no abnormal and significant changes of water discharge in other stations;(3)the sediment discharge only has significant change at the Shijiao station in 1999, which is controlled by the construction of the upstream reservoir. However, the sediments have the abnormal changes at the other four stations, and the change time and reason of each station are different. The sediment discharges of Gaoyao station and Makou station changed around 1999—2000, and the main control factor is the construction of upstream reservoirs and dams. The sediment discharges of Sanshui station in the main stream of the North River and Boluo station in the East River changed in 2003 and 1988 respectively, which is mainly caused by water and soil conservation in the upper reaches. In conclusion, the variation of water and sediment discharges in the lower reaches of the Pearl River Basin is mainly controlled by human activities. Understanding its variation mechanism is of great significance to the protection and sustainable utilization of the estuarine ecological environment.