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1. Modeling Dependence in Hydrological Frequency Analysis using Copula | |||
XU Yueping,TONG Yangbin,XU Xiao | |||
Hydraulic Engineering 29 December 2011 | |||
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Abstract:Although the importance of multivariate analysis has already been recognized, dependences among different variables are often ignored due to the complexity of problem. It is known that doing so may induce great modeling risk that potentially exist, and will jeopardize the successive hydrosystem analysis, design and management. In this paper, the copula approach is proposed to model the dependence among rainfall data of different durations. Several well-known copulas are chosen and compared, among which the Gaussian copula is found to be the best one. In the meanwhile, rainfall data is simulated using the copula approach and it is found out that the simulated rainfall data preserve quite well the statistical characteristics of actual data. | |||
TO cite this article:XU Yueping,TONG Yangbin,XU Xiao. Modeling Dependence in Hydrological Frequency Analysis using Copula[OL].[29 December 2011] http://en.paper.edu.cn/en_releasepaper/content/4457093 |
2. Uncertainty Analysis of Design Flood Estimation in Ungauged Basins | |||
TONG Yangbin,XU Yueping,XU Xiao | |||
Hydraulic Engineering 22 December 2011 | |||
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Abstract:This paper focused on analyzing different sources of uncertainties in design flood estimation. First, in the analysis of methodology uncertainty, Regional Synthetic Method (RSM) and L-moments Method (LMM) were used to calculate design rainfall depths, thus to estimate design flood. Also, three simple 24-hour-hyetographs were considered, with peak rainfalls at different times. Second, a Monte Carlo simulation based on Latin Hypercube Sampling (LHS) was employed to estimate the input and parameter uncertainty. A small ungauged basin in Zhejiang Province was used as an example. Results showed that for return periods more than 10 years, the peak flows derived through RSM were larger than that through LMM, indicating that RSM was more conservative and contained more uncertainties. Besides, small change of peak flows for different hyetographs could also be observed. With regard to input and parameter uncertainty, the model was run 1000 times and it was found that the peak flow distribution could be represented by the normal distribution. The statistical characters of simulated peak flow also presented that as the return periods increased, the coefficient of variation grew, slowly though, indicating increased uncertainty. | |||
TO cite this article:TONG Yangbin,XU Yueping,XU Xiao. Uncertainty Analysis of Design Flood Estimation in Ungauged Basins[OL].[22 December 2011] http://en.paper.edu.cn/en_releasepaper/content/4457090 |
3. Study of dams\ | |||
Zhangping Wei,Han Chang-hai | |||
Hydraulic Engineering 20 October 2009 | |||
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Abstract:The continuous ecosystems of natural rivers are altered by construction of dams, which has several negative impacts on fishes. Those mainly includes: (1) Barrier of fishes migration routes, (2) Changes of hydrological and hydraulic conditions for fishes spawning, (3) Reduction and destruction of habitats, (4) Influences of gas supersaturation, (5) Influences of discharged low-temperature water. This paper summarizes some research achievements home and abroad, and then it offers two kinds of solutions to those problems: One is engineering measure, such as installing environmentally friendly hydropower turbines and building ecological fish passages in hydraulic structures; the other is non-engineering measure, which includes Fishes Nature Reserves, ecological compensation and regulation, artificial propagation and stocking, etc. | |||
TO cite this article:Zhangping Wei,Han Chang-hai. Study of dams\[OL].[20 October 2009] http://en.paper.edu.cn/en_releasepaper/content/35937 |
4. Application of TOPMODEL in Streamflow Stimulation and Baseflow Separatio | |||
Wen Pei,Chen Xi,Chen Yongqin | |||
Hydraulic Engineering 20 March 2006 | |||
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Abstract:TOPMODEL is a widely used hydrological model which has been applied to study spatial variations of hydrologic processes and to distinguish hydrological components. In the original TOPMODEL structure, total runoff is divided into surface water and baseflow and no perched interflow is allowed. This would result in over-estimation of baseflow from the groundwater with a permanent table. A modified TOPMODEL by Scanlon et al. (2000) including storm flow within the subsurface is used to simulate streamflow and to separate subsurface storm flow from baseflow in the XingFeng catchment, one of the Dongjiang subasins in Zhujiang watershed. The topographic indices of the basin are calculated to represent the controlling factor of spatial variations of hydrology. They were calculated by the program of GRIDATB written by Keith Beven in 1983 using the digital elevation model (DEM) with spatial solution of a 25m grid. Daily observed precipitation amount from five rainfall observation stations, pen evaporation and stream discharge series in the period from 1982 to 1985 are used for model parameter calibration and those data from 1986 to 1987 are applied for model validation. The simulation results show the Nash and Sutcliffe efficiency coefficient (NSE) of daily streamflow is 0.79 in the calibration period and 0.72 in the verification period. Moreover, nine flood events were selected for hourly streamflow simulation. Mean NSE for the nine flood events is 0.85. Therefore, the model is capable of stimulating streamflow in the study catchment. The baseflow is separated from the total streamflow discharges on the basis of concept of the modified TOPMODEL runoff generation. Study results indicate that baseflow amount of the flood events is approximately 75 percent of total streamflow. | |||
TO cite this article:Wen Pei,Chen Xi,Chen Yongqin. Application of TOPMODEL in Streamflow Stimulation and Baseflow Separatio[OL].[20 March 2006] http://en.paper.edu.cn/en_releasepaper/content/5803 |
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