鄱阳湖水龄时空特征和影响因素分析

换水能力是表征湖泊水动力和污染物输移扩散的关键指标,鄱阳湖水文情势波动显著,换水能力时空特征和影响因素复杂。本文选取水龄描述鄱阳湖换水能力,建立鄱阳湖水龄模型,研究了鄱阳湖水龄的时空特征和影响因素,分析了水龄对鄱阳湖江湖关系演变的响应规律。结果表明:(1)鄱阳湖水龄具有显著的时空异质性。夏季和秋季水龄明显大于冬季和春季,碟形湖和湖湾区域水龄明显大于主河道和滩地。(2)湖口水位和流域入流是影响鄱阳湖水龄的主要因素。湖口水位对鄱阳湖水龄的影响大于流域入流;湖口水位越高则鄱阳湖水龄越大,流域入流与之相反;鄱阳湖水龄年内显著波动的主要原因是湖口水位的年内显著变化。(3)2003年后,随着江湖关系的演变,鄱阳湖水龄有所减小,其中秋季减小最为明显。研究成果能为鄱阳湖水资源保护提供科学支撑,也可为其他大型湖泊换水能力研究提供参考。

Spatial and temporal characteristics and influencing factors of water age in Poyang Lake

Water exchange capacity is a key index to characterize the hydrodynamic and pollutant transport and diffusion of lakes. The hydrological regime of Poyang Lake fluctuates violently,and the spatial and temporal characteristics and influencing factors of water exchange capacity are complex. In this paper, water age is selected to describe the water exchange capacity of Poyang Lake, and the water age model of Poyang Lake is established. The temporal and spatial characteristics and influencing factors of water age are studied,and the response law of water age to the evolution of River-Lake relationship is analyzed. The results show that:(1) the water age of Poyang Lake has significant temporal and spatial heterogeneity. The water age in summer and autumn is significantly longer than that in winter and spring, and the water age in inner lake and bay area is significantly longer than that in main river channel and beach. (2) The water level at Hukou and the inflow of the basin are the main factors affecting the water age of Poyang Lake. The influence of the water level at Hukou on the water age of Poyang Lake is greater than that of the basin inflow; the higher the water level at Hukou, the longer the water age of Poyang Lake, while the inflow of the basin is the opposite; the main reason for the drastic fluctuation of the water age of Poyang Lake is the drastic change of the water level at Hukou. (3) After 2003, with the evolution of the River-Lake relationship, the water age of Poyang Lake decreases, especially in autumn. The research results can provide scientific support for the protection of water resources of Poyang Lake, and also provide reference for the study of water exchange capacity of other large lakes.