Chen, H.

Holbach, A.

Hu, W.

Norra, S.

Schleicher, N.

Wang, L.

Zheng, B.

KITopen

Geophysical Research AbstractsVol. 14, EGU2012-11782-3, 2012EGU General Assembly 2012© Author(s) 2012Impact factors on water quality in the confluence zone of the DaningRiver and the Yangtze River at different hydrological conditions in theThree Gorges ReservoirA. Holbach (1), L. Wang (2), H. Chen (2), W. Hu (1), N. Schleicher (1), B. Zheng (2), S. Norra (1,3)(1) Institute of Mineralogy and Geochemistry (IMG), Karlsruhe Institute of Technology (KIT), Adenauerring 20b, 76131Karlsruhe, Germany, (2) Chinese Research Academy of Environmental Sciences (CRAES), No.8, Dayangfang, AnwaiBeiyuan, Chaoyang District, Beijing, China, 100012, (3) Institute of Geography and Geoecology (IfGG), Karlsruhe Instituteof Technology (KIT), Reinhard-Baumeister-Platz 1, 76128 Karlsruhe, GermanyWater quality of the Three Gorges Reservoir (TGR) in the Yangtze River became a major concern since the firstclosure of the dam in 2003. Increasing eutrophication and algal bloom events, especially in confluence bays andbackwater areas are observed. Substance transport, water exchange and interaction between water masses in con-fluence areas of tributaries and the Yangtze main stream are of special interest and mainly driven by large scalewater level fluctuations and temporal discharge variations in the reservoir. The Daning River, one tributary of theTGR also adjoins to Dachang city and Wushan city which are by backwater of the TGR.In the frame of the Sino-German “Yangtze-Project” [1] water quality data and samples were collected in the Dan-ing River and its confluence zone with the Yangtze River during two fieldtrips in August and December, 2011.Remarkable hydrological changes during the sampling time were present in August whereas conditions in Decem-ber were rather stable.Water quality data was recorded in-situ and on-line in varying depths with a towed underwater sensor system.The monitored data comprise seven important physico-chemical water parameters (temperature, electrical conduc-tivity, turbidity, dissolved oxygen, oxygen saturation, pH, chlorophyll a) coupled with a 3D positioning system.Geostatistical evaluation and interpolation of the physico-chemical water parameter data was conducted to get 3Ddistribution models for the parameters in the water bodies. Selective water samples for analysis of inorganic com-ponents (anions, cations, nutrients) in the dissolved and particulate phases were taken from different depths by afree flow sampler.Results reveal that pollutant plumes in the water above the thermocline surround the urban areas during the stableconditions of December. In August the degree of mixing of Yangtze main stream water with the Daning Riverwater was the main driving force for the water chemistry. Contrarily, water quality was mainly controlled by thedevelopment and the collapse of a separated temperature layered water body in the confluence bay at Wushan.Main algal growth was limited to the confluence areas in the vicinity of the cities during both sampling periods.Consequently, water chemistry and water quality of the confluence zone are both strongly dependent on the hydro-logical and seasonal weather conditions but are not necessarily related to each other.Future work will focus on this and other study areas in the TGR covering different seasonal and hydrological con-ditions. Results will also be used as input data for the numerical modeling in the Yangtze-Project [1]. Importantknowledge for the understanding of long-term pollutant dynamics and water quality tendency in the TGR and otherreservoirs can be achieved.AcknowledgmentsThe Yangtze-Project is funded by the Federal Ministry of Education and Research (BMBF grant no. 02WT1131)of Germany and the International Science and Technology Cooperation Program of China (NO. 2007DFA90510).Many thanks to the Environmental Monitoring Station in Wushan, Chongqing, China for great administrative andinfrastructural support.References[1] Bergmann A, et al. (2011) The Yangtze-Hydro Project: a Chinese–German environmental program. Environ-mental Science and Pollution Research. Doi: 10.1007/s11356-011-0645-7

Impact factors on water quality in the confluence zone of the Daning River and the Yangtze River

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Impact factors on water quality in the confluence zone of the Daning River and the Yangtze River

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