鄱阳湖出湖流量时序变化特征与驱动因子分析

长江中游与鄱阳湖及五河构成复杂的“江-湖”系统，研究阐明鄱阳湖出湖流量的时序变化特征与驱动因子，是调控改善江湖关系的关键所在。本文在初步选取12个潜在的出湖流量驱动因子基础上，有机结合相关系数判别和主成分分析方法，揭示了不同潜在驱动因子间的多重共线性；进而通过构建出湖流量数学模型，量化了不同潜在驱动因子对出湖流量的相对重要性排序及其影响程度。研究结果表明：（1）赣江、抚河、饶河、修水的入湖流量，湖区星子站水位，三峡出库流量等6个驱动因子间不存在多重共线性，可完整表征五河来流、湖区水位、长江干流的多重驱动作用；（2）运用基于随机森林回归方法的出湖流量数学模型，揭示了湖区水位、长江干流来流、赣江入湖流量是最为重要的驱动因子，并且其对出湖流量的影响呈现复杂的非线性特征。研究表明：影响出湖流量的众多驱动因子之间关系复杂但影响程度有所差异。这为科学调控典型通江湖泊江湖关系提供了重要参考依据。

Characteristics of time-series variations and driving factors of Poyang Lake outflows

The middle Yangtze River, Poyang Lake, and its five tributaries form a complex "river-lake" system, and understanding the time-series variation characteristics of the lake outflow and its driving factors is key to regulation and improvement of the river-lake relationship. This paper first selects 12 potential drivers of the outflow and illustrates the multi-collinearity among these drivers by combining the correlation coefficient evaluation criterion method and principal component analysis. Then, we construct a mathematical model of the lake outflow based on the random forest regression method, and use it to quantify the relative importance and effects of different potential drivers on the outflow. The results show that 1) no multi-collinearity has been observed among six driving factors－outflows from the Ganjiang, Fuhe, Raohe and Xiushui tributaries, lake stage at Xingzi, and outflow from the Three Gorges reservoir, which can fully characterize the multiple driving effects of the tributaries, lake water stage, and Yangtze mainstream. 2) We reveal that the top three effects come from lake stage, Yangtze mainstream discharge, and Ganjiang River outflow; the influence of the main driving factors is complicated and nonlinear. And relationships among all these six factors are also complicated and their influences are different. This study would deepen our understanding of the relationship underlying this river-lake system and be useful for river-lake regulation.