Using stable isotopes and hydrochemistry for interaction evaluation between surface water and groundwater in the South of Hanoi

Combination between δ¹⁸O and δ²H stable isotopes and hydrochemistry properties of water helps to understand the distribution and movement of wells from Holocene (qh) and Pleistocene (qp) aquifers in the south of Hanoi area. The results of the hydrochemistry analysis indicated that wells and surface water polluted by BOD₅, COD and NH₄ values over allowance of the Vietnam National Standards. The stable isotopes values of the surface water are range from -4.87‰ to -9.82‰ for δ¹⁸O values and from -41.8‰ to -64.05‰ for δ²H values. The δ¹⁸O and δ²H stable isotopes values of the groundwater are range from -2.03‰ to -14.83‰ and -26.11‰ to 97.12‰, respectively. Based on stable isotope characteristics, the results show that 100% of the groundwater is recharged from rivers in rainy season. In the dry season, groundwater is recharged from rivers and rainfall with different percentages. (author)