Stable isotope geochemistry of Oxygen and Hydrogen: A case study of the Satluj River Basin, India

Stable isotope analysis of hydrogen and oxygen is one of the important methods used to model the hydrological cycle. Oxygen and hydrogen isotopic investigation of river water, its tributaries, and groundwater of its catchment from the Satluj basin was undertaken to estimate the contributions of the main sources comprising discharge during major periods throughout a hydrologic year.

Estimation of the snow/glaciers melt contribution is also very important for tracing the sources and processes regulating the flow from the provenance and reservoirs in the context of global warming, for estimating flood flow, and for other water resource development activities in large parts of the Indian subcontinent. Water samples were collected during the non-monsoon season at increasing altitudes. In this work, in addition to stable isotopes, we also assessed the water quality using various physicochemical parameters and geochemistry of the water.

From isotopic analyses of river water samples, the mean value of the δ¹⁸O was found to be ~ -13‰, and the mean value of δD was found to be~ -85‰. For the samples from Satluj tributaries, the mean value of the δ¹⁸O was ~ -11‰, and the mean value of δD was ~ -69‰. A mean value of -8.4‰, was found based on the δ¹⁸O measurements of the groundwater samples, while the average δD value was found to be ~ -55‰.

For the mainstream and tributary, LWL, y = 8.2604x +20.208, and range of d-excess (>10‰) and y = 8.2079x + 22.182 and d-excess > 10‰ indicates a system recharged by sources of recycled moisture derived from continental sources in addition to monsoonal climates. For the groundwater data, the slope is 6.7, and d-excess ranges from 7‰ to 17‰. These observations are suggestive of the monsoonal source of Indian Ocean precipitation that has experienced significant evaporation during the non-monsoon season.

Our new data clearly shows that the surface water whether mainstream, tributary, and groundwater isotopes are homogenized from regional trends in precipitation, modified by evaporation, and are thus greatly influenced by latitude, elevation, and patterns of climate.