No abstract

Poyang Lake in Jiangxi Province is the largest freshwater lake in China and is historically a region of significant floods. Annual events of peak lake stage and of severe floods have increased dramatically during the past few decades. This trend is related primarily to levee construction at the periphery of the lake and along the middle of the Changjiang (Yangtze River), which protects a large rural population. These levees reduce the area formerly available for floodwater storage resulting in higher lake stages during the summer flood season and catastrophic levee failures. The most severe floods in the Poyang Lake since 1950, and ranked in descending order of severity, occurred in 1998, 1995, 1954, 1983, 1992, 1973, and 1977. All of these floods occurred during or immediately following El Niño events, which are directly linked to rainfall in central China. The 2-year recurrence interval for maximum annual lake stage during El Niño years is 1.2 m higher than during non-El Niño years. The 10-year recurrence interval is 1.4 m higher during El Niño years than during non-El Niño years.

No abstract

Jiangxi Province in southeastern China contains Poyang Lake, the largest freshwater lake in China. Poyang Lake and the lower sections of the major Jiangxi rivers flowing into the lake often flood during the early summer months. Floodwater can be several meters above the surrounding lowlands during the most severe flood events. Levees at the margins of Poyang Lake and along the Jiangxi rivers provide flood protection for about 10 million people. The number of severe floods in this region has increased rapidly during the past few decades, resulting in catastrophic levee failures. The three factors likely responsible for the increasing frequency of severe floods are (1) land reclamation and levee construction and (2) lake sedimentation, both of which reduce lake volume, and (3) increasing Changjiang water level, which slows Poyang Lake drainage.