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Characterization of Mixing Processes in the Confluence Zone between the Three Gorges Reservoir Mainstream and the Daning River Using Stable Isotope Analysis
journal contribution
posted on 2015-08-30, 00:00 authored by Yunyun Zhao, Binghui Zheng, Lijing Wang, Yanwen Qin, Hong Li, Wei CaoUnderstanding the interaction processes
between the mainstream
and its tributaries and detailing the rates of contribution of water
and nutrients from two different waterbodies in the confluence zone
are essential for water management in the Three Gorges Reservoir (TGR).
The stable isotope ratios of hydrogen (δD) and oxygen (δ18O) were applied to explore the interactions between the TGR
mainstream and a typical tributary, the Daning River. The results
of the model calculations showed that approximately 78.9% of the water
and 88% of the nitrate in the confluence zone were from the TGR mainstream.
The dynamic vertical distributions of the mixing ratios, major ion
contributions, and flow velocities indicated that the water mass from
the Yangtze River mainstream flowed backward from the confluence zone
up to the tributary along the surface and upper-middle layers, whereas
water from the tributary flowed into the mainstream through the lower-middle
and bottom layers. This study demonstrates the value of hydrogen and
oxygen isotope tracers in accurately describing water mass mixing
processes and estimating the rates of contribution of different nutrient
sources in the confluence zone, which will provide valuable information
for controlling algal blooms in the future.