中文摘要：

鄱阳湖近年低枯水位频繁发生，引起了人们广泛的关注．鄱阳湖作为吞吐型湖泊，通过狭长的湖口水道与长江自然相通，其水力特性直接影响着长江与鄱阳湖的相互作用关系．基于水力学方法，提出湖泊泄流能力的概念，并采用湖泊水文观测数据，研究了鄱阳湖的泄流能力特征及其近年的演变过程．结果表明，2000s之前鄱阳湖泄流能力基本维持不变，之后迅速提高，近年开始趋于稳定．泄流能力的显著提高改变了鄱阳湖与长江相互作用的水力特性，从而影响了鄱阳湖的水量平衡，加剧了近年枯水情势．研究表明，大规模采砂是鄱阳湖泄流能力变化的主因，应加强鄱阳湖采砂管理．

英文摘要：

The recently frequent low water level in Lake Poyang attracted wide public attention, As an open lake, Lake Poyang is naturally connected with the Yangtze River via the Hukou Waterway. The interactions between the Yangtze River and the Lake Poyang are directly affected by the flow characteristics of the Hukou Waterway. The discharge capacity is introduced to represent the ability to convey water away using the hydraulic approach. The discharge capacity and its change is investigated here. Results show that ： The discharge capacity was stable before 2000s and thereafter it rapidly increased. Its remarkable increase altered the interaction between the Yangtze River and Lake Poyang, leading to the recent severe drought regime. Largescale sand dredging in Lake Poyang is attributed to be the cause of this increase. The management for sand dredging should be strengthened for conserving the water resources in Lake Poyang.