Mapping groundwater renewability using age data in the Baiyang alluvial fan, NW China

Huang, Tianming; Pang, Zhonghe; Li, Jie; Xiang, Yong; Zhao, Zhijiang

Mapping groundwater renewability using age data in the Baiyang alluvial fan, NW China | Cartographie du renouvellement des eaux souterraines au moyen de données d’âge dans le cône alluvial de Baiyang, NW de la Chine Mapeo de la renovabilidad del agua subterránea utilizando datos de edad en el abanico aluvial de Baiyang, NW de China 基于年龄数据评价白杨河地区地下水可更新能力 Mapeando a renovação das águas subterrâneas utilizando dados de datação no leque aluvial de Baiyang, NO China

2017

Huang, Tianming | Pang, Zhonghe | Li, Jie | Xiang, Yong | Zhao, Zhijiang

Groundwater age has been used to map renewability of water resources within four groups: strong, partial, and rare renewability, and non-renewable. The Baiyang alluvial fan in NW China is a representative area for examining groundwater recharge from river infiltration and for mapping groundwater renewability, and it has been investigated using multiple isotopes and water chemistry. Systematic sampling included 52 samples for ²H and ¹⁸O analysis and 32 samples for ³H, ¹³C and ¹⁴C analysis. The δ¹³C compositions remain nearly constant throughout the basin (median −12.7‰) and indicate that carbonate dissolution does not alter ¹⁴C age. The initial ¹⁴C activity of 80 pmC, obtained by plotting ³H and ¹⁴C activity, was used to correct groundwater ¹⁴C age. The results show that areas closer to the river consist of younger groundwater ages; this suggests that river infiltration is the main recharge source to the shallow groundwater system. However, at distances far away from the river, groundwater ages become older, i.e., from modern water (less than 60 year) to pre-modern water (from 60 to 1,000 years) and paleowater (more than 1,000 yeas). The four classifications of groundwater renewability have been associated with different age ranges. The area of shallow groundwater with strong renewability accounts for 74% of the total study area. Because recharge condition (river infiltration) controls overall renewability, a groundwater renewability map is of significant importance to the management of groundwater exploitation of this area as well as other arid groundwater basins.

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