Identifying the groundwater flow systems in a condensed river-network interfluve between the Han River and Yangtze River (China) using hydrogeochemical indicators

Zhang, Jingwei; Liang, Xing; Jin, Menggui; Ma, Teng; Deng, Yamin; Ma, Bin

Identifying the groundwater flow systems in a condensed river-network interfluve between the Han River and Yangtze River (China) using hydrogeochemical indicators | Identification des systèmes d’écoulement des eaux souterraines dans l’interfluve d’un réseau de rivières dense entre la rivière Han et le fleuve Yangtzé (Chine), à l’aide d’indicateurs hydrogéologiques Identificación de los sistemas de flujo de agua subterránea en una red de drenaje entre el Río Han y el Río Yangtze (China) utilizando indicadores hidrogeoquímicos. 利用水文地球化学指标识别汉江与长江之间河网密布地块中的地下水流系统分布 Identificando os sistemas de fluxo de águas subterrâneas em um interflúvio de rede fluvial condensada entre o Rio Han e o Rio Yangtze (China) utilizando indicadores hidrogeoquimicos

2019

Hydrogeochemistry and environmental isotopes were used to gain insight into the recharge processes, water–rock interactions, and groundwater residence time, and to identify groundwater flow systems (GFSs) in an interfluve between the Han River and Yangtze River in the eastern Jianghan Plain (China), an alluvial-lacustrine plain in the middle reaches of the Yangtze River. Because of carbonate mineral weathering, groundwater in the plain is predominantly HCO₃-Ca or HCO₃-Ca-Mg type. The decrease in typical ions and isotopic depletion with increasing depth indicates that the GFSs were divided into local and regional GFSs with an approximate depth limitation of 20 m. The consistent variations are attributable to complex anthropogenic activities, water–rock interactions and groundwater flow patterns. The multiple independent local GFSs exhibited a pattern in which groundwater was discharged into surface waters during the non-flood season. Groundwater age of local GFSs is modern according to the ³H concentrations, so the hydrodynamic circulation is active. Furthermore, the regional GFS pattern is controlled by slow lateral flow from west or northwest to east, eventually discharging into the Yangtze and Han rivers. The distribution of δ¹⁸O indicated three zones in regional GFSs that are likely dominated by the altitude effect of recharge areas. The groundwater age of regional GFSs varied from hundreds of years to 5000 years, estimated by ¹⁴C isotope data, revealing that the hydrodynamic circulation of regional GFSs is slow to relatively stagnant. The hydrodynamic characteristics and hydrochemical distributions corroborated the mixing zones of differently hierarchical GFSs in the discharge area of the Jianghan Plain.

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