鄱阳湖五河入湖水沙通量及典型断面形态变化特性分析

五河入湖水沙通量及河道形态变化对五河尾闾演变、湖区低枯水位、江湖关系等研究有重要意义。以1956—2018年实测资料为基础,利用Mann-Kendall 检验法和河道特征对五河入湖水沙通量、典型断面形态变化特性及其影响因素进行了研究。结果表明:①五河入湖径流量总体呈小幅度减小态势,2003—2018年五河入湖平均径流量较1956—2002年减小5.3%;②除饶河外,入湖泥沙通量均有不同幅度的减小,其中赣江和信江大幅度减小,2003年后分别减少约72.3%和52.6%;③五河典型断面形态2014年前变化较大,断面多呈锯齿状;随后逐渐恢复正常;④水利枢纽工程、水土保持工程和人工采砂是影响五河入湖泥沙通量和河道形态的主要人为因素。

Changes of Water and Sediment Flux and Typical Sectional Shape of Five Rivers Flowing into the Poyang Lake

The change of water and sediment flux and channel morphology of five rivers into the Poyang Lake is of great significance to the study of river tail evolution, low and dry water levels in the lake area, as well as river-lake relations. According to measured data from 1956 to 2018, the changes in water and sediment flux and typical sectional morphology are examined using Mann-Kendall test method. Factors affecting such changes were also investigated. Results reveal that: (1) The water inflow of the five rivers decreased in a small extent. Compared with that from 1956 to 2002, the average runoff of the five rivers into the Poyang Lake decreased by 5.3% from 2003 to 2018. (2) Except from Raohe River, the sediment flux into the lake decreased by different ranges. In particular, the sediment flux in Ganjiang River and Xinjiang River declined by large margins, about 72.3% and 52.6% respectively after 2003. (3) The typical sectional shape of the five rivers changed markedly before 2014, and the cross sections were mostly zigzag. Afterwards, the cross sectional shape gradually returned to normal. (4) Water conservancy project, soil and water conservation project, as well as artificial sand mining are major human factors that affect the sediment flux and channel morphology of the five rivers into the Poyang Lake.