Laterally averaged two-dimensional modeling of thermal structure in river-type reservoirs
Dai Lingquan1,2, Dai Huichao1,2, Mao Jingqiao2, Jiang Dingguo1
1.College of Hydraulic and Environmental Engineering, China Three Gorges University, Yichang, Hubei 443002, China; 2.College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing, Jiangsu 210098, China
Abstract：The impoundment of the reservoirs has a strong influence on the hydrologic regime of the natural river course, and the water thermal structure characteristics maybe change at the same time. In this work, a laterally averaged two-dimensional model for river-type reservoirs to simulate water temperature is developed. Taking the Three Gorges Reservoir(TGR)show as an example, the thermal structure after the operation of the TGR is predicted based on a normal year and an extreme dry year. Results show that the temperature has marked difference in the longitudinal direction in Spring and Summer, the commonly used one-dimensional model is difficult to reflect the real vertical temperature distribution near far from the dam; the reservoir has no stable thermal stratification during the whole year in different typical years, but in Spring, a transient and weak stratification may arise, the maximum temperature difference in the vertical direction in a normal year is 8.14 ℃,while it is 8.82 ℃ in an extreme dry year. The regions of the large temperature gradient(<100.0 m)are located below the elevation of the power plant intake(130.0 m).The water in the region with the large temperature gradient does not affect the discharged flow from the Three Gorges Reserovir in Spring.Therefore, the results can provide a scientific basis for management of the ecological environment in the Three Gorges Reservoir.
[1]Jung S W, Kwon O Y, Yun S M, et al. Impacts of dam discharge on river environments and phytoplankton communities in a regulated river system, the lower Han Ri-ver of South Korea[J]. Journal of Ecology and Environment, 2014,37(1): 1-11.[2]Dembski S, Masson G, Monnier D, et al. Consequences of elevated temperatures on life-history traits of an introduced fish, pumpkinseed Lepomis gibbosus[J]. Journal of Fish Biology, 2006,69(2): 331-346.[3]Garcia Alex, Jorde Klaus, Habit Evelyn, et al. Downstream environmental effects of dam operations: Changes in habitat quality for native fish species[J]. River Research and Applications, 2011,27(3): 312-327.[4]Reinfelds Ivars, Marcus Lincoln Smith, Haeusler Tim, et al. Hydraulic assessment of environmental flow regimes to facilitate fish passage through natural riffles:Shoalhaven river below tallowa dam, new south wales, Australia[J]. River Research and Applications, 2010,26(5): 589-604.[5]Gao Xin, Lin Pengcheng, Li Mingzheng, et al. Effects of water temperature and discharge on natural reproduction time of the chinese sturgeon, acipenser sinensis, in the Yangtze River, China and impacts of the impoundment of the Three Gorges Reservoir[J]. Zoological Science, 2014,31(5): 274-278.[6]Li Ran, Li Jia, Li Kefeng, et al. Prediction for supersaturated total dissolved gas in high-dam hydropower projects[J]. Science in China Series E-Technological Sciences, 2009,52(12): 3661-3667.[7]Politano Marcela, Haque Mdm, Weber Larryj. A numerical study of the temperature dynamics at McNary Dam[J]. Ecological Modelling, 2008,212(3/4): 408-421.[8]Caudill C C, Keefer M L, Clabough T S, et al. Indirect effects of impoundment on migrating fish: Temperature gradients in fish ladders slow dam passage by adult chinook salmon and steelhead[J]. Plos One, 2013,8(12): 1-13.[9]Ferreira Danielimara, Cunha Cynara. Numerical simulation of the temperature dynamics at Rio Verde Reservoir[J]. Engenharia Sanitaria E Ambiental, 2013,18(1): 83-93.[10]脱友才, 刘志国, 邓云, 等. 丰满水库水温的原型观测及分析[J]. 水科学进展, 2014,25(5): 731-738. Tuo Youcai, Liu Zhiguo, Deng Yun, et al. Water temperature of the Fengman reservoir with seasonal ice cover [J]. Advances in Water Science, 2014,25(5): 731-738.(in Chinese)[11]Becker V, Huszar V L M, Naselli F L, et al. Phytoplankton equilibrium phases during thermal stratification in a deep subtropical reservoir[J]. Freshwater Biology, 2008,53(5): 952-963.[12]Gooseff M N, Strzepek K, Chapra S. Modelling the potential effects of climate change on water temperature downstream of a shallow reservoir, Lower Madison Ri-ver, MT[J]. Climatic Change, 2005,68(3): 331-353.[13]熊伟, 李克锋, 邓云, 等. 一二维耦合温度模型在三峡水库水温中的应用研究[J]. 四川大学学报:工程科学版, 2005,37(2): 22-27. Xiong Wei, Li Kefeng, Deng Yun, et al. Application of 1D and 2D coupling temperature model in the Three-Gorge Reservoir[J]. Journal of Sichuan University:Engineering Science Edition, 2005,37(2): 22-27.(in Chinese)[14]马方凯, 江春波, 李凯. 三峡水库近坝区三维流场及温度场的数值模拟[J]. 水利水电科技进展, 2007,27(3): 17-20. Ma Fangkai, Jiang Chunbo, Li Kai. Numerical simulation of 3D flow field and temperature field near dam area of Three-Gorges Reservoir[J]. Advances in Science and Technology of Water Resources, 2007,27(3): 17-20.(in Chinese)[15]Besma Zouabi-Aloui, Moncef Gueddari. Two-dimensional modelling of hydrodynamics and water quality of a stratified dam reservoir in the southern side of the Mediterranean Sea[J]. Environmental Earth Sciences, 2014,72(8): 3037-3051.[16]Wang Xixi, Yang Wanhong. Modelling potential impacts of coalbed methane development on stream water quality in an American watershed[J]. Hydrological Processes, 2008,22(1): 87-103.
