Earth Science Frontiers ›› 2025, Vol. 32 ›› Issue (2): 445-455.DOI: 10.13745/j.esf.sf.2024.7.56

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Interaction between the river and groundwater in the Dongting Lake during extreme climate: Taking the Zijiang River segment in the Dongting Lake as an example

CHEN Hongwei1,2,3(), ZHU Zhichao1, LI Zhengzui4, YU Weihou4, ZHOU Hui4, YU Shasha4, PENG Xiangxun1,2,3   

  1. 1. School of Hydraulic and Environmental Engineering, Changsha University of Science & Technology, Changsha 410114, China
    2. Key Laboratory of Water-Sediment Sciences and Water Disaster Prevention of Hunan Province, Changsha University of Science & Technology, Changsha 410114, China
    3. Key Laboratory of Dongting Lake Aquatic Eco-Environmental Control and Restoration of Hunan Province, Changsha University of Science & Technology, Changsha 410114, China
    4. Hunan Hydrology and Water Resources Survey Center, Changsha 410005, China
  • Received:2024-05-30 Revised:2024-06-19 Online:2025-03-25 Published:2025-03-25

Abstract:

Setting 2022 as the time background, and the Zijiang River segment in Dongting Lake as the study area, hydrochemistry and Rn isotope tracing were adopted to study the river-groundwater interaction in the Dongting Lake, and to reveal the abnormal change of the water exchange along rivers under the extreme climate condition. In January and August, the hydrochemistry type of the river water was HCO3-Ca, and that of the groundwater was HCO3-Ca and HCO3-Ca to HCO3 ·SO4-Ca, respectively. The rock leaching are the main controlling factor of the river water and groundwater, and river water and groundwater may have experienced mixing. The 222Rn concentration in the groundwater in January and August was 21 and 23 times that of the river water, respectively, and 222Rn in the river and groundwater in January were higher than that in August. In January and August, TDS and Cl- in the river fluctuated slightly along the river, while those in the groundwater increased and decreased in great degree with similar overall trend to the river water. 222Rn in the river and groundwater fluctuated greatly and increased first and then decreased along the river in January, while that in the two types of water bodies changed with opposite tendency along the upper part of the river, and with similar characteristics along the lower part of the river in August. The hydrochemistry and Rn isotope characteristics indicated that the groundwater discharge into the river along the upper and lower part of the study river segment, and the discharge weakened along the middle part in January and August. The discharge rate and flux along the study river segment in January and August was 0.39×10-4 and 0.44×10-4 m3/(s·m) and 1.24 and 1.39 m3/s, respectively. The extreme climate resulted in the abnormal change of river-groundwater interaction in Dongting basin. Along the study river segment, the groundwater discharge intensity increased in January, and the recharge model changed from river-into-groundwater to groundwater-into-river in August. The extreme climate not only influenced the model and intensity of the water exchange along rivers in the Dongting Basin, but probably caused the abnormal change of matter cycle and energy flow in the river ecosystem.

Key words: hydrochemistry, Rn isotope, river water, groundwater, interaction, extreme climate, Dongting Lake

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