River–lake water exchange reflects hydrological connectivity and the dynamic relationship between the river and the lake. The water exchange is crucial for lake level variation, downstream river discharge and the ecosystem. To figure out the water exchange between the Yangtze River and Poyang Lake, a data‐driven model was established based on the support vector regression and genetic algorithm technique. Nine scenarios were set with different river–lake hydrological conditions, divided into two categories: single‐element change scenarios, where only the river conditions or only the lake conditions changed, and combined scenarios, where both elements changed simultaneously. The model could accurately simulate the river–lake water exchange variations. Scenario simulation results show that increasing the river flow or lowering the lake level could cause a decrease in the lake outflow. Conversely, decreasing river flow or raising the lake level could cause an increase in lake outflow. Changing lake conditions have a stronger impact on the water exchange variation than changing river conditions if the change percentages of the situation indicator values are the same. Similarly, lake level increase has a stronger impact on the water exchange variation than lake level decrease. The combined scenarios indicate the additive effect of the corresponding single‐element change scenarios, with a clear linear relationship between their lake outflow changes. This study provides an efficient model for simulating complex hydrological flow relationships in river–lake systems, and supports the management of the Yangtze River and Poyang Lake by providing the characteristics and causes of the river–lake water exchange.

中文翻译：

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大型河湖系统中的水交换：模型，特征和原因

河湖水交换反映了水文连通性和河流与湖泊之间的动态关系。换水对于湖泊水位变化，下游河流排放和生态系统至关重要。为了弄清长江与Po阳湖之间的水交换，基于支持向量回归和遗传算法技术建立了数据驱动模型。设定了九种情景，其中河湖水文条件不同，分为两类：单要素变化情景，其中仅河流条件或湖泊条件发生变化；组合情景，其中两个要素同时变化。该模型可以准确模拟河湖水交换变化。方案模拟结果表明，增加河流流量或降低湖泊水位可能会导致湖泊流出量的减少。相反，减少河流流量或提高湖泊水位可能导致湖泊流出量增加。如果情况指标值的变化百分比相同，则变化的湖泊条件对变化的影响比变化的河流条件更强烈。同样，湖泊水位增加对水交换变化的影响要大于湖泊水位减少的影响。组合方案表明了相应的单元素变化方案的累加效应，其湖泊出水量变化之间具有明确的线性关系。这项研究为模拟河湖系统中复杂的水文流动关系提供了有效的模型，