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Li Y.Y.,Chinese Ministry of Water Resources | Cao J.T.,Chinese Ministry of Water Resources | Shen F.X.,Chinese Ministry of Water Resources | Xia J.,State Key Laboratory of Water Resources and Hydropower Engineering Science | Xia J.,Chinese Academy of Sciences
Science China Earth Sciences | Year: 2014

Water is a critical natural resource upon which all social and economic activities and ecosystem functions depend. With a surprising social and economic development in the past decades, water has become an important constraint for China's sustainable development, and a matter concerning economic security, ecological security and national security of the country. Understanding the changes of water resources is greatly helpful in analyzing the impacts of climatic change, formulating plans for utilization and protection of water resources, and making water resource decisions. Based on China's national water resources assessment, the Mann-Kendall's test, and Morlet wavelet, we analyzed the changing trends and periods of China's renewable water resources during 1956-2010. The results as following: (1) There is no significant change trend of water resources on the countrywide scale during the period 1956-2010, the total water resources show a slight increasing trend, and the national annual average water resources during the period 1991-2010 increased by 1% relative to that of the period 1961-1990. (2) The changes of water resources in different level-I water resource regions vary significantly. Annual average water resources of the Haihe River and Yellow River regions in the northern China decreased 19% and 17% respectively in the past 20 years. Water resource increased in Southern and Northwestern rivers regions, particularly in the Northwest rivers region, with the increasing amplitude by nearly 10% in the past 20 years. (3) The inter-annual variation of national water resource became larger in the past 20 years, as compared with that of the period 1961-1990. The coefficients of water resource variation increased in Northwestern and Southwestern rivers regions, while the inter-annual variation tended to decrease in the Haihe and the Yellow River regions where significant decline of water resources happened. (4) A 14-year quasi-periodicity of the national water resource variation was detected, overlapping with various periodicities of water resources of different level-I water resource regions. Remarkable uniformity exists between the first or secondary primary periodicity of water resource variation in adjacent level-I water resource regions. © 2014 Science China Press and Springer-Verlag Berlin Heidelberg. Source

Jin Z.,Wuhan University | Hu T.,State Key Laboratory of Water Resources and Hydropower Engineering Science
Wuhan Ligong Daxue Xuebao (Jiaotong Kexue Yu Gongcheng Ban)/Journal of Wuhan University of Technology (Transportation Science and Engineering) | Year: 2012

Pivoting Algorithms is a method for solving linear inequalities and linear programming problems, however, it is different from traditional simplex method in that the algorithm is based on the row processing and you needn't add any slack, surplus or artificial variables. In addition, by combination of tables, the method can also solve similar problems such as Linear multilevel programming and linear bilevel multi-follower programming with dependent followers (stackelberg-nash equilibrium), and so on. If using "top-down" approach to solving price control problem, you can do so by cutting plane method to obtain global optimization. Finally, an example of price control problem shows the method is effective and efficient. Source

Chen Z.,State Key Laboratory of Water Resources and Hydropower Engineering Science | Chen Z.,Wuhan University of Technology | Cui Y.,State Key Laboratory of Water Resources and Hydropower Engineering Science | Liu F.,Jiang Xi Province Irrigation Experiment Station
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2013

Farmland soil is often in alternating wet and dry state, which seriously affected the change of soil composition and properties, and thus changed soil hydraulic properties. During the course of alternation of wetting and drying, along with the change of water content, soil bulk density would change accordingly. The experimental investigations of this paper were carried out in irrigation field of Jiangxi province irrigation experiment station. The rice planting field trials were launched by employing experimental treatment with two irrigation modes including flooding, intermittent irrigation and four fertilization mode including no nitrogen fertilizer, nitrogen-containing compound fertilizer, controlled-release nitrogen fertilizer, organic and inorganic nitrogen fertilizer. Through analyzing change of soil specific volume with water content of all the tested soil undisturbed soil, the method of statistical analysis was used to fit the soil quality index curve model of water content and soil specific volume relationship. And main influence factors of soil wetting expansion and drying shrinkage were obtained by gray correlation analysis. The results showed that the index model can be used to describe the soil expansion process and shrinkage process under different irrigation and fertilization modes. a (dry soil, reciprocal of dry soil volume mass) and b (the natural logarithm unit value of soil specific volume change when unit water content change) values in soil shrinkage characteristics curve index models of different irrigation and fertilization mode were not the same with responding expansion curve index models. Soil shrinkage curve and expansion curve were two mutually non-coincident curves, b values and their differences in two curves were also different and lag phenomenon was existed. Soil wet expansion and dry shrinkage characteristics were affected by a variety of soil properties, which was mainly reflected through the effect of pore structure in soil and water holding properties. Source

Fu L.,Hunan Electrical Science Research Institute | Kou P.G.,Hunan Electrical Science Research Institute | Cheng Y.G.,State Key Laboratory of Water Resources and Hydropower Engineering Science
Advances in Power and Energy Engineering - Proceedings of the 8th Asia-Pacific Power and Energy Engineering Conference, APPEEC 2016 | Year: 2016

The hydraulic turbine vibration is the most important factor influencing the safe operation of hydropower station. Because of the relatively wide vibration area, the regulating capacity of the Francis turbine has been greatly limited in the grid. In order to analyze the mechanisms of inducing vibration of the Francis turbine, the 3-D CFD model of Francis turbine has been established and analyzed using numerical simulation in this paper. And the results of CFD numerical simulation are compared with the data of field testing. Through the numerical simulation, the mechanisms of inducing vibration and the variation of the pressure fluctuation have been identified. And in this paper, the pressure fluctuation contours of Francis turbine has been drawn out by the calculation in 25 conditions and the study can guarantee the hydropower station’s safe and stable operation. © 2016 Taylor & Francis Group, London. Source

Wu H.,Hunan University | Zeng G.,Hunan University | Liang J.,Hunan University | Guo S.,Hunan University | And 9 more authors.
Ecological Indicators | Year: 2015

In this study, we used the soil microbial biomass (SMB) and the bacterial community structure as indicators to determine the potential ecological responses of the Dongting Lake wetland (China) to the early dry season that has been induced by the Three Gorges Dam (TGD), the largest hydroelectric project in the world. We measured the soil properties, SMB and bacterial community structure for samples E0, E20 and E40 (for which the dry season arrived early by 0, 20 and 40 days, respectively). The results indicated a significant increase in SMB as the dry season occurred increasingly earlier. The microbial biomass carbon (MBC) was used as a representative for the SMB and increased for the samples in the following order: E0 < E20 < E40. The bacterial 16S rDNA gene copy number changed similarly to the MBC. Significant changes were also observed in the soil bacterial community structure. The bacterial community structure of E40 was more diverse than that of E20, which was similar to that of E0. The relationship between the bacterial community composition and the soil properties was evaluated by redundancy analysis (RDA). The results indicated that the lead time of the dry season was the controlling influence on the soil bacterial community structure. © 2015 Elsevier Ltd. All rights reserved. Source

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