| 摘要: |
| 流域河流新水比例和滞留时间是表征径流过程以及污染物、营养物质运输的重要参数。确定水的来源及其在流域内的滞留时间,对于理解流域水文过程和功能至关重要。为了定量解析鄱阳湖流域河流的新水比例和滞留时间,本文通过对鄱阳湖流域高频率的降水及河水(赣江、修河、信江、抚河、饶河,以下简称“五河”)稳定同位素(δ18O和δD)的监测与分析,利用正弦拟合方法分析了降水和河水δ18O和δD值变化。结果表明：(1)“五河”河水及降水氢氧同位素表现出相似的季节变化特征,雨季(5~7月)较为贫化,旱季(12月~次年2月)较为富集,河水同位素变化与局地降水同位素、地下水同位素密切相关,说明流域内不同水体之间存在良好的水文连通性；(2)“五河”流域内小于3个月的新水占比范围为3 %~42 %,流域内滞留时间范围为124天~2497天,其中赣江平均滞留时间最长、新水比例最低,乐安河和昌江的新水比例最高、平均滞留时间最短；(3)流域面积和单位面积上干流长度是“五河”流域新水比例的主要控制因素,坡度与新水比例存在负相关关系,但其负相关性被单位面积上干流长度与新水比例的正相关性所掩盖；(4)修河、赣江流域较其他流域显著受到蒸发分馏的影响；(5)鄱阳湖湖水同位素值明显高于河水,且在湖口站点湖水同位素值较都昌站点偏低,这表明湖口站湖水受长江来水和蒸发分馏的影响。该研究结果有助于对鄱阳湖流域水文联系和水文过程解析,可为流域污染物的输移模拟及其机制阐释等方面提供科学参考。 |
| 关键词: 鄱阳湖流域 新水比例 平均滞留时间 氢氧同位素 水文过程 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金项目（42071145; 42201105）；江西省自然科学基金（20232BAB213053） |
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| Quantifying the young water fraction and residence time of the |
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likaiwen1, fanhongxiang2, wuhuawu2, leiruiyu2, dingmengyao2, fucongsheng2, lijing3, xinwei4, zhangcicheng1
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1.Hunan Normal University, School of Geographical Sciences;2.Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences;3.Chuzhou University, School of Geographic Information and Tourism;4.Institute of Hydrobiology, Chinese Academy or Sciences
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| Abstract: |
| Young water fraction and mean residence time of rivers in a watershed are crucial parameters for describing the runoff process, as well as the transport of pollutants and nutrients. They help determine the source of water and its residence time within the watershed, playing a pivotal role in understanding watershed behavior and functionality. In order to quantitatively analyze the young water fraction and mean residence time of rivers in the Poyang Lake catchment, this study conducted high-frequency monitoring and analysis of stable isotopes (δ18O and δD) in precipitation and river water (including the Gan River, Xiu River, Xin River, Fu River, and Rao River, hereafter referred to as the "Five Rivers"). The study utilized a sine fitting method to analyze the variations in δ18O and δD values in precipitation and river water. The results indicate: (1) the hydrogen and oxygen isotopes in the "Five Rivers" water and precipitation exhibit similar characteristics. They show depletion during the rainy season (May to July) and enrichment during the dry season (December to February of the following year). The study suggests a close correlation between river water isotopic variations and local precipitation isotopes as well as groundwater isotopes, indicating good hydrological connectivity among different water bodies in the watershed; (2) the young water fraction in the "Five Rivers" catchment, with the age less than 2 months, ranges from 3% to 42%, and the mean residence time varies from 124 days to 2497 days. Among them, the Gan River has the longest mean residence time and the lowest young water fraction, while the Le"an River and Chang River exhibit the highest young water fraction and the shortest mean residence time; (3) catchment area and the length of the main stream per unit area are identified as the primary controlling factors for the young water fraction in the "Five Rivers" catchment. Slope is negatively correlated with the young water fraction, but this negative correlation is overshadowed by the positive correlation between the length of the main stream per unit area and the young water fraction; (4) the Xiu River and Gan River catchment are significantly influenced by evaporative fractionation compared to other catchment; (5) the isotopic values of Poyang Lake water are significantly higher than those of river water, and the isotopic values at the Hukou station are lower than those at the Duchang station. This indicates a significant influence of Yangtze River and evaporative fractionation on Poyang Lake water. The results of this study contribute to the understanding of hydrological connections and processes in the Poyang Lake catchment, providing a scientific reference for the simulation of pollutant transport and the interpretation of mechanisms. |
| Key words: Poyang basin young water fraction mean residence time hydrogen and oxygen isotopes hydrological processes |
