Assessing the recharge process and importance of montane water to adjacent tectonic valley-plain groundwater using a ternary end-member mixing analysis based on isotopic and chemical tracers
- National Chung Hsing University, Department of Soil and Environmental Sciences (China)
- Industrial Technology Research Institute (China)
- Council of Agriculture, Eastern Region Branch, Agriculture and Food Agency (China)
- Taiwan Agricultural Research Institute, Agricultural Chemistry Division (China)
- Ministry of Economic Affairs, Central Geological Survey (China)
A study in eastern Taiwan evaluated the importance of montane water contribution (MC) to adjacent valley-plain groundwater (VPG) in a tectonic suture zone. The evaluation used a ternary natural-tracer-based end-member mixing analysis (EMMA). With this purpose, VPG and three end-member water samples of plain precipitation (PP), mountain-front recharge (MFR), and mountain-block recharge (MBR) were collected and analyzed for stable isotopic compositions (δ{sup 2}H and δ{sup 18}O) and chemical concentrations (electrical conductivity (EC) and Cl{sup −}). After evaluation, Cl{sup −} is deemed unsuitable for EMMA in this study, and the contribution fractions of respective end members derived by the δ{sup 18}O–EC pair are similar to those derived by the δ{sup 2}H–EC pair. EMMA results indicate that the MC, including MFR and MBR, contributes at least 70% (679 × 10{sup 6} m{sup 3} water volume) of the VPG, significantly greater than the approximately 30% of PP contribution, and greater than the 20–50% in equivalent humid regions worldwide. The large MC is attributable to highly fractured strata and the steep topography of studied catchments caused by active tectonism. Furthermore, the contribution fractions derived by EMMA reflect the unique hydrogeological conditions in the respective study sub-regions. A region with a large MBR fraction is indicative of active lateral groundwater flow as a result of highly fractured strata in montane catchments. On the other hand, a region characterized by a large MFR fraction may possess high-permeability stream beds or high stream gradients. Those hydrogeological implications are helpful for water resource management and protection authorities of the studied regions.
- OSTI ID:
- 22780854
- Journal Information:
- Hydrogeology Journal, Vol. 26, Issue 6; Other Information: Copyright (c) 2018 Springer-Verlag GmbH Germany, part of Springer Nature; Country of input: International Atomic Energy Agency (IAEA); ISSN 1431-2174
- Country of Publication:
- United States
- Language:
- English
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