Application of isotope techniques to study groundwater resources in the unconsolidated aquifers along the Ping River (Thailand)^*

ABSTRACT

Severe droughts during the dry season and floodings during the rainy season are among the major problems encountered in the valleys along the Ping River in Thailand. Improving our understanding of the groundwater resources in this agricultural area is an important issue for the sustainable development of the region. Hence, in order to gain understanding on the groundwater flow dynamics in the unconsolidated shallow aquifers along the Ping River, stable (¹³C, ¹⁸O, ²H, noble gases) and radioactive (³H, ¹⁴C) isotope techniques were combined with hydrogeochemical tools. The comprehensive interpretation of the chemical and isotope data consistently showed different origins for groundwater in the northern and southern areas of the investigated aquifers. Groundwaters in the northern part have younger ³H/³He ages, are less mineralized, and have suffered a stronger evaporation than groundwaters in the southern part of the aquifer. Overall, our results are consistent with the hydrogeological situation of the investigated area, namely shallow groundwaters and a spatially extended recharge. ³H/³He apparent ages indicated that young groundwater (<50 years) is present in all the investigated wells. Elevated concentrations of some pollutants (nitrate and phosphate) in parts of the aquifer evidenced a relatively high vulnerability of the aquifer to surface pollution.

KEYWORDS:

• Carbon-13
• carbon-14
• groundwater origin
• hydrogen-2
• hydrogen-3
• isotope hydrology
• noble gases
• oxygen-18
• Ping River
• Thailand
• shallow aquifer

Disclosure statement

No potential conflict of interest was reported by the author(s).

ORCID

Jose A. Corcho Alvarado http://orcid.org/0000-0002-4472-2756

Notes

* Originally presented at the IAEA Symposium on Isotope Hydrology 2019, Vienna, Austria, 20–24 May 2019.

Additional information

Funding

We thank the International Atomic Energy Agency for funding this study though the Technical Cooperation Project THA/7/005 ‘Applying Isotope Hydrology to the Study of Surface and Groundwater Mixing in the Unconsolidated Aquifer Along Lower Ping River’.