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Yan B.,Huazhong University of Science and Technology | Guo S.,Wuhan University | Yu W.,Changjiang Water Resources Commission Changjiang Institute of Survey
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2013

Coincidence of flood hydrograph can be generalized as mathematical constraints of date interval and magnitude for flood occurrence. A multivariate hydrological analysis model was developed to estimate the flood coincidence risk between the Yangtze and the Qing River. In this model, the mixed von Mises distribution was introduced to describe the interval, and a Copula function was adopted to establish a trivariate distribution of the 15-days flood volume and its interval for each river. By this model, a coincidence risk of 21. 9% was evaluated, the risk characteristics for different combinations of flood frequencies of the two rivers were analyzed. The results would provide a technical support to the united compensational operation of reservoirs on the Yangtze and the Qing River. Source

Wang J.,Hohai University | Li J.N.,Changjiang Water Resources Commission Changjiang Institute of Survey | Zhu S.,Hohai University
Advanced Materials Research | Year: 2014

This paper discussed the mechanism of dilatancy in coarse grained soils. Large-scale triaxial tests were also conducted to study the dilatancy law of coarse grained soils. Based on the results of the previous studies, it is found that plastic potential function proposed by Lade can fit the test results well. Lade's dilatancy rule was then applied to a practical two-yield-surface model. Elastoplastic formula of the two-yield-surface model was also deduced in detail. The new model was verified with several groups of different materials. Results showed that this model could predict the behaviors of coarse grained soils well. © (2014) Trans Tech Publications, Switzerland. Source

Zhang C.,North China Electrical Power University | Li Q.,YELLOW AND CO | Qian J.,Changjiang Water Resources Commission Changjiang Institute of Survey
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2014

Effective scheduling is crucial to the operation of a large water transfer channel. To reduce the scope of negative influences by channel regulation, we developed a new concept called partition schedule. In this work, the South-to-North Water Transfer Project (SNWTP) was taken as a case study. We adopted a downstream control method and developed a 1-D unsteady flow model to study two partition schedules: a sequential schedule and an alternative schedule under certain maximum amplitude of water level. This paper presents the simulation results and determines the key factors of great influence on the system's safety and stability. Results show that partition schedule is effective for operation and control of large transfer channel and it reduces wave influencing scope and number of control gates required. Optimal partition schedules are also presented. © Copyright. Source

Liu Y.Y.,Changjiang Water Resources Commission Changjiang Institute of Survey | Liu B.J.,Hubei Provincial Water Resources and Hydropower Planning Survey and Design Institute
Applied Mechanics and Materials | Year: 2014

Hydrologic responses to climate change have become a great challenge and attracted widespread attention of the researchers. The mountainous Qingyi River watershed in the southwest, China, had experienced significant climate change in the past three decades. It is necessary to investigate the hydrologic responses to these changes. Therefore, the effect of climate change on evapotranspiration (ET), surface runoff, baseflow and streamflow were assessed using Variable Infiltration Capacity (VIC) hydrologic model. The Mann-Kendall test analysis was first used to identify the long-term change in precipitation and temperature over the period of 1980-2010. It revealed that there is a significant change in annual temperature particularly in February, March, July and September, whereas an insignificant change in annual precipitation was founded. Hydrologic simulations show that hydrologic responses to climate change were varied from region to region. Surface runoff was more sensitive than ET and baseflow. Monthly variation of the hydrologic processes, especially the change in surface runoff, was mainly attributed to seasonal variation in precipitation. The results of this research can be a useful source of information for the decision making in water resources management and protection. © (2014) Trans Tech Publications, Switzerland. Source

Chen Y.,CAS Research Center for Eco Environmental Sciences | Wang X.,CAS Research Center for Eco Environmental Sciences | Jiang B.,Changjiang Water Resources Commission Changjiang Institute of Survey | Yang N.,CAS Research Center for Eco Environmental Sciences | Li L.,CAS Research Center for Eco Environmental Sciences
Urban Forestry and Urban Greening | Year: 2016

Urban greening is becoming increasingly popular in cities around the world, which is leading to the planting of more and more trees in paved areas in urban environments. However scientifically it is not well understood how pavement may impact tree greening efforts. In this paper, we investigated plant responses to pavement in the suburb of Changping District, Beijing, China. We planted the popular deciduous ash tree (Fraxinus chinensis) in three different pavements: pervious bricks; impervious bricks; and no pavement (i.e., control) at three densities (0.5 m × 0.5 m, 1.0 m × 1.0 m, and 2.0 m × 2.0 m apart). We investigated the influence of pavement type on plant phenology by monitoring soil temperature and moisture as well as leaf budburst rate from January to April in 2014. Our results show that pavement can significantly increase soil temperature, and decreased soil moisture except pervious pavement at the 1.0 m × 1.0 m density. The significant relationship between the leaf budburst rate and accumulated soil temperature implies that pavement induced soil warming can accelerate leaf budburst, suggesting that pavement contributes to tree leaf budburst acceleration by probably both increasing soil and air temperatures in urban environments. © 2016 Elsevier GmbH. Source

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