Isotopic Characterization of River Waters and Water Source Identification in an Inland River, Central Asia

Yuting Fan,Yaning Chen,Weihong Li,Qing He,Yun Wang

doi:10.3390/w8070286

Yuting Fan, Yaning Chen + Show 3 more

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https://doi.org/10.3390/w8070286

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Abstract

Understanding runoff generation and dynamics is the basis for water resource management, while water isotopic ratios are a potential tool for studying the mechanism on a large scale. In this paper, spatial variations of δ18O and δD of river water and their sources within a large region of the Tarim River were investigated. The results showed obvious spatial variations of both water isotope values along the river flow direction, and significant seasonal variation occurred within the river water isotopes. This indicated that different proportions of rain and melt water entering river water should lead to spatial variation, and for mid-stream and downstream regions, the transformation relationship between surface water and groundwater should consider less input of melt water. Furthermore, we quantitatively determine the ratio of different water sources using the stable isotope mass balance method and other stable tracer elements. Results showed the contribution of ice-snowmelt water varied from 14.97% to 40.85%, that of rain varied from 9.04% to 54.80%, and that of groundwater varied from 15.34% to 58.85%, and they also showed that baseflow is a factor connecting melt water and groundwater, which meant the Hotan River and the Yarkand River are melt water–dependent rivers, and seasonal precipitation is the main water supply source of baseflow in the Aksu River and the Kaidu River.

Highlights

Water demand consistently exceeds supply in many parts of the world, especially in the arid and semi-arid regions [1,2]
Through a review of published papers, we found there are still opportunities for improving the understanding of groundwater isotopes: (1) quite a few studies quantified the recharge proportion via kinetic fractionation of stable isotopes in the large inland rivers of Central Asia and (2) there are several shortcomings associated with the quantitative assessment of ice-snowmelt water and baseflow for mountain-plain areas
Studies have demonstrated that baseflow has a strong correlation with climate, so the baseflow index is an important factor linking ice-snowmelt water and groundwater recharge

Summary

Introduction

Water demand consistently exceeds supply in many parts of the world, especially in the arid and semi-arid regions [1,2]. The Tarim River Basin, with a size of 1.02 ˆ 106 km , is the largest inland river basin in Central Asia. The basin occupies about two-thirds of the total area of Xinjiang (the largest provincial administration unit of China). This northwestern arid inland region is situated far from the sea with a typical continental climate, lack of precipitation, intensive evaporation, and extremely fragile ecological environment. The Tarim is a typical braided river, forming a north-south alluvial plain with a width of more than 100 km [3]

Results

Discussion

Conclusion