• 全国中文核心期刊
  • 中国科技核心期刊
  • 美国工程索引(EI)收录期刊

2008 Vol. 19, No. 6

Display Method:
Regionality and persistence of extreme precipitation events in China
MIN Shen, QIAN Yong-fu
2008, 19(6): 765-771.
Abstract:
Based on daily rainfall dataset of 542 stations in China between 1960-2003,the regionality and persistence characters of extreme precipitation(EP) are briefly studied in this paper.The results indicate that the persistence of EP in the west of Yunnan and the east of Tibet is higher,while the regionality is lower in these areas.In summer,both the two characters in the south of the Yangtze River are evidently larger,which can induce the regional floods easily.In winter,both the twa characters in the southeast coastal areas are better which might lead to regional stmng rainfall events lasting for three or more days.Both the two characters in Middle-and Low-reaches of the Yellow River are also good in autumn,so that the flood may happen quiet possibly in these areas in the season.The two characters of EP in rmst northern areas of China,except Xmjiang, are qmte poor.
An integrated assessment of climate change impacts on China’s water resources
REN Guo-yu, JIANG Tong, LI Wei-jing, ZHAI Pan-mao, LUO Yong, MA Zhu-guo
2008, 19(6): 772-779.
Abstract:
The newly advances in the climate change and China's water resources are given in this paper.The results and findings show that the current water resource issue in China is related not only to the rapid growth of population and economic, but also to the obvious climate change and variability over the past 50 years.Future change in climate will probably lead to further shortage of water resources in some river basins and more severe floods in others, threatening the sustainable development of the catchments.The authors recommend that more attention be given to the issue of climate change and variability in planning and managing major river basins' water resources in the future.
Experimental study on the fractionation mechanism of hydrogen and oxygen stable isotopes in evaporation from water surface of evaporation pans
BAO Wei-min, HU Hai-ying, WANG Tao, QU Si-min
2008, 19(6): 780-785.
Abstract:
There is a close relationship between meteorological factors and evaporation.In this paper, the relationship between evaporation fractionation factor of stable isotopes and meteorological factors is analyzed through the water evaporation experiments under different meteorological conditions.The results indicate that the residual water is gradually enriched in heavy isotopes along with the evaporation In the outdoor evaporation experiment, isotopic stratification phenomenon takes place in different water layers of the evaporation pans where the isotopic ratios of surface water are more concentrated than that of deeper water due to the discrepancy of the sunlight radiation, heat convection and wind speed.It is also shown that the fractionation factor of stable isotopes is inversely proportional to the evaporation temperature.Moreover, the evaporation line of outdoor experiment obviously deviates from the local meteoric water line, which demonstrates that the evaporation action of the surface water is strong in course of the experiment Therefore, the research provides credible experimental data for revealing the evaporation fractionation mechanism further.
Changes of pan evaporations and its impact factors over northern Tibet in 1971-2006
DU Jun, BIAN Duo, BAO Jian-hua, LA Ba, LU Hong-ya
2008, 19(6): 786-791.
Abstract:
With the data of mthly 20cm pan evaporation and its impact climatic facts at 6 meteorological status over northern Tibet form 1971 to 2006, the trend is analyzed through the linear trend analysis.The main results are as follaus:(1) Significant negative trend of annual pan evaporation is detected at all stations of northern Tibet, and the mean rate of decrease is 6117 mm per 10-year (99% confidence level),especially in summer(-2018 mm per 10-year, 99% confidence level).The spatial distribution of the change rate shows that the decrease of annual pan evaporation mainly occurs in mid-western of northern Tibet, the decreasing rate declines with the increase of longitude and rises with the elevation of altitude.(2) Significant decrease trends of annual sunshine duration and wind speed are found over northern Tibet.Significant positive trends of annual mean relative humidity and precipitation are detected. So is significant increase trend of annual mean temperature, with its increase is 0.34 e per 10-year.While the increase trend of annual mean minimum temperature(0.54 e per 10-year) is bigger than that of annual mean maximum temperature(0.17 e per 10-year), and the trend of daily temperature range decrease significantly(-0.37 e per 10-year).And (3) it is thus obvious that the decrease of the pan evaporation is mainly caused by the significant decrease of the daily temperature range and sunshine duration as well as the obviously increase of the mean relative humidity.Precipitation and wind speed may also play an important role in the unknown mechanism.
Analysis of the precipitation stability and variety trend in the desert region of northern China
XU Li-gang, ZHOU Hong-fei, LI Yan, LI Hui, TANG Ying
2008, 19(6): 792-799.
Abstract:
With the run theory,the displacement and extremum deviation theory,the stability of precipitation are analyzed by the rmnthly precipitation data from 35 sites in the desert region of northern China during 1951-2005.Based on the MannKendall rank statistic method and 2-parameterrainfall concentration index and interannual rainfall variability,the characteristics of precipitation in the temporal and spatial variety are analyzed.Results indicate that:(1) In every where,the probability of high-flow year alone is higher than that of low-flow year alone,and the probability of low-flow year in succession is higher than that of high-flow year in succession,and (2) in extreme arid regions and arid regions,such as Xmjiang,Qinhai and Gansu,the probability of precipitation increase 83% and 70% respectively.On the contrary,in semi-arid regions,like Inn Mongolia,the probability of precipitation decreases by 58%.
Hierarchical comparison of alternatives in water transfer project
LIU Jian-chang, WANG Li-min, ZHANG Wei, MU Cong-ru, FAN Xiu-ying
2008, 19(6): 800-806.
Abstract:
Alternative comparison in water transfer project plays an important role in the project feasibility research and the environmental impact assessment.The hierarchical comparison of alternatives, a new technology for project assessment, is developed based on the features of water transfer.The shallow lake, Baiyangdian, is selected as a case study to make a hierarchical comparison of alternatives in water transfer from two upstream reservoirs.Results indicate that the hierarchical comparison of alternatives is proved to be useful in assessing the effectiveness of all alternatives in comparison with convent ional methods, can availably avoid pretermission of alternatives, and compare the analytic alternatives scientifically.
Full implicit numerical method for two-dimensional shallow flows in orbicular river cell
XIANG Xiao-hua, SU Chang-cheng, WU Xiao-ling, WANG Chuan-hai
2008, 19(6): 807-813.
Abstract:
Based on the generic 2D river-network model, a generic numerical model for 2D orbicular river cell is presented by applying the full implicit matrix chase-after method.Accoreding to the modeling method for 1D river-network, the model estabilishes the equations of water level nodes which can be easily used to realize the 2D river-network and 1D-2D coupling rivernetwork by a implicit way.With the numerical results about Yangtze Rive branch of BAGUA island in NANJING, it can be indicated that the model is effective and valuable.
Relationship between abutment dimension and the downstream recirculation length
JIA Dong-dong, WANG Bo, ZHOU Gang, SHAO Xue-jun
2008, 19(6): 814-820.
Abstract:
The relationship between the longitudinal dunension of an abutment and the recirculation length behind it is established based on the expennental data and the numerical results using a 3D model.The law of wall and the large coefficient method are used in the 3D model.The results show that the length of recirculation decxeases with rise in the ratio of longitudinal dunension(b) to lateral dunerrsion(D).The recirculation length is sensitive to changes in b/D when b/D is small, and becomes a constant when b/D is larger than 4, at which the results are equivalent to the solutions to sudden expansion prolr lens.A formula is proposed to calculate the length of recirculation for longitudinal dunension of an alxztment.
Study on the precision of second order algorithm for smoothed particle hydrodynamics
ZHENG Xing, DUAN Wen-yang
2008, 19(6): 821-827.
Abstract:
The smoothed particle hydrodynamics(SPH) is one of mesh-free methods and has been widely developed during these years.This numerical method has many advantages for free surface problems and large deformation problems,because of its mesh-free andLagrangian characters.But this method still exists some disadvantages at present,like low accuracy of calculation,rmre computational expense.According to the shortcomings of onginal SPH method,this paper focuses on the impnwement of precision.Fnrstly,the foundation theory of onginal SPH method is introduced in brief,according to the precision analysis,the ream of low precision for the traditional method is pointed out,and second order SPH method is introduced.Then though the verification and analysis of accuracy,it is concluded that the precision of this new method achieves second order.Rnally,based on the twa dimension numerical tests,the error distributions of the function values,first order and second order derivatives are given by the original and modified method,when the particles are arranged at two ways,uniform distribution and non-uniform distribution.The results demonstrate that the second order method can overcome some shortcoming of the traditional method,and the precision can be improved effectively.
Effect of bed discordance on helix flow at Y shaped junction
WANG Xiao-gang, YAN Zhong-min, ZHANG Xing-nong
2008, 19(6): 828-834.
Abstract:
The structure of flow is very complex at Y shaped junction where there are multiform helix flows.This paper analyzes the effect of bed discordance (the ratio of bed discordant height between mainstream and tributary channel to the tailwater depth) on helix flow at Y shaped junction through the three-dimensional numerical simulation.The flow is dominated by two helical cells, usually back-to-back at Y shaped junction The bed discordance will decrease the intensity of helix flow at the side of mainstream channel and increase it at the side of tributary.When the intensity of helix flow is very strong at the side of tributary, the helix flow will be destroyed at the side of mainstream channel.
Analysis of the saltwater intrusion in the Changjiang estuary during the flood season in extreme drought year
DAI Zhi-jun, LI Wei-hua, LI Jiu-fa, CHEN Ji-yu
2008, 19(6): 835-840.
Abstract:
Based on the hourly discharge records at the Datong station and the measured data of hydrology and salinity in the Chan自fang estuary during the flood season in the extreme drought 2006 coinciding with the operation of the large hydropower engineering,the characteristics of the saltwater intrusion and the changes of the freshwater caused by the saltwater intrusion are discussed.The results show that:① During the extreme drought year,the intensity of both the saltwater intrusion in the north branch and the inverse intrusion into the Ruth Branch is strengthened in the period of the spring tide,especially in Oct.2006,which resins from the absence of the freshwater in the river segments of Chenghang reserwir and Baogang resemvir;② The main way of inversed intrusion of the saltwater in the north branch goes clearly via the north channel of Baimaosha into the south branch,and the diluted water in the Chan自fang River evidently from the south channel of Baimaosha to the south branch.The flowing water from these different ways meets in the back of the Baimaosha and extends over the region of the Wusong inlet;And ③ because the region of the Wusong inlet is affected by the action of the saltwater intrusion from the north passage and the south passage,freshwater resource can be found there.I}wever,the seaward segment of the Wusong inlet is covered by the high saltwater body.
Application of SPH to numerical simulation of discharge through crest orifice on dam
LI Da-ming, LIU Jiang-chuan, XU Ya-nan
2008, 19(6): 841-845.
Abstract:
The paper studies the smooth particle hydrodynamics(SPH) method and establishes rmdel of discharge through crest orifice on dam.The author applies the SPH model to the flow of liquid with free surface on Laxiwa dam,simulates the process of the discharge of the surface outlet.The water recharge boundary is used in the rmdel.The paper gives the an analysis of the numerical pressure and the experimental pressure.The results indicate that it is possible to simulate and research high-speed flow using the smooth particle hydrodynamics method.
Parallel computation for 2D flow model
ZUO Yi-ming, CUI Guang-bai
2008, 19(6): 846-850.
Abstract:
This article develops a parallel depth-averaged 2D flow model.Since the message passing interface has not implemented the process transference function,the article researches message parallel platform for the model.The platform adopts ant algorithm to schedule tasks and constitutes message protocol to pass message.After its applying it to changjiang river of neijiang,the results indicate that if machines count is less than the oriental count,the consumed time increases along with the adding machine count and vice versa.
3D turbulence model for the flow and sediment transport with aquatic vegetation
LIU Cheng, SHEN Yong-ming
2008, 19(6): 851-856.
Abstract:
Aquatic vegetation plays an important role in the flow structure in open channels and thus changes the fate and transport of sediment.This paper proposes a 3D turbulence rmdel,introducing vegetation density and drag force to the control equations of water flow with vegetation.The impacts of submerged vegetation on the vertical profiles of horiwntal flow velocities,the changes of the depth-averaged flow velocities in a compound channel with emergent vegetation in the floodplain,and the bed surface topography changes around and in a vegetation island are calculated by the model.The calculated results show a good agreement the with experimental results.
Influence of sediment concentration on deposition of silt and runoff hydraulics on grassland
PAN Cheng-zhong, MA Lan, SHANGGUAN Zhou-ping
2008, 19(6): 857-862.
Abstract:
In order to reveal the performance of grass strips on silt-laden flow with high sediment concentration, the experiments were carried out on different sediment concentration of 0-350 kg/m3 in grassplots on the slope of 3° and 9° and discharge of 20 and 60 L/min, and the deposition of sediment and hydraulic characteristics of runoff were analyzed.The results show that the sediment mass deposited on grassplots increase with the concentration.There is a positive relationship between the deposition rate and the sediment concentration at 3°, but a negative relationship at 9°.Under the experimental conditions, the discharge plays a negligible role in the total mass of sediment deposition, but slope significantly affects the sediment deposition.The flow velocities at downslope are greater than that at upslope, and the sediment concentration has a minor influence on the velocity.On the same slope and discharge, the Reynolds number of silt laden flow decreases with the increase of sediment concentration Runoff resistance coeff icient (f) and Manning roughness (n) increase with sediment concentration at 3°, but there is no significant correlation between them at 9°.Therefore, sediment concentration should be considered in the estimation of hydrological processes in the region with severe soil erosion.
Experiment study on static yeild stress with hypoconcentration muddy water
QIN Yi, CAO Ru-xuan, ZHENG Xue-ping, CHEN Jie
2008, 19(6): 863-867.
Abstract:
By the means of experiment this paper probes into the shear stress of the static muddy water.The experiment indicates that the value of the static yield stress is larger than that measured from pressure capillary rheometer and increases with the resting time and the sediment content and is negatively proportion to the particle size.It is learned from the water channel conceptualized experiment that the a static shear stress produces the resistance of the hypoconcentrated laminar flow change with time, and this stress is the root of the globule siltation resulting in the cease of the whole hypoconcentrat ion muddy water flow near boundary of a channel and the root of natural barrier formtion.
Relationship between sediment transport with surface rainfall and runoff energies on sloping
LI Guang-lu, WU Fa-qi, PANG Xiao-ming, ZHAO Xiao-feng
2008, 19(6): 868-874.
Abstract:
From the view of rainfall and runoff energies resulting in soil erosion,this paper puts forward the conceptions of rainfall energy and runoff energy on the base of physics principle,and analyses the relationship between sediment transport with rainfall energy and runoff energy using the artificial rainfall.The results show that the rate of sediment detachment of sloping fallow overland flow increases with the rise of the slope gradient,rainfall energy and runoff energy,and the sediment detachment rates under raindrop impact are severe higher than under those without raindrop impact.The sediment concentration increases with the increase of the slope gradients and rainfall energies;when slope gradients and rainfall energy keep a constant,the sediment concentrations decrease with the increase of the runoff energies.Rainfall disturbed coefficients have a logarithm correlation with the rate of rainfall energy and runoff energy.On same slope gradient,when the rainfall energies keep a constant,the disturbed coefficient decreases as the runoff energies increases,when the runoff energies keep a constant,it increases as the rainfall energy increases.The rainfall energy is the essence to result in sediment detachment,and the runoff energy is the conveyer for erosion sediment.
Numerical simulation of fully nonlinear focused wave groups
NING De-zhi, TENG Bin, TAN Li, ZHOU Bin-zhen
2008, 19(6): 875-881.
Abstract:
The propagation of transientwave groups, focused on a point in time and space to produce waves with steepness, is simulated by resolving Laplace,duation using the higer-order boundary element method in the tune domain, in which the fully nonlinear boundary conditions and serni-mixed EulerLagrange method are used to track free surfazee.The fourtlrorder Runga Kutta method is used to comput the wave elevation and velocity potential on the free surface at each tune step.The 2nd-order Stokes analyical velocity is given at the incident boundary to generate the input wave.The unage Green function is applied in the present study so that the integration on the lateral surfaces and bottom are exduded.The experunental study on the focused wave groups with different wave slopes is carried out in awave flume.And the numerical solutions are compared with the ex perunental results.The characters of the nonlinear focused wave groups are studied here.
Characteristics of ice regime in the lower Yellow River
DONG Xue-na, LI Xue-mei, LIN Yin-ping, YAO Hui-ming
2008, 19(6): 882-887.
Abstract:
The characters of ice regime in the lower Yellow River are as follows:the reach is completely freezing in winter for some years,and freezing-free for some others;in the reach,the freeze-up date is earlier,the break-up date later;and the freeze-up period is longer,and the ice-cover is thicker and solider than that of the upstream;the ice flood is characteristics of the small flow,high water level and increase from the upriver channel to downriver channel.In recent 20 years,the ice regime has changed with the discharge decreasing at large scale,the sustaining high temperature and the reserwirs, control,so that the dates of the freeze-up and break-up are brought forward;the river length and ice volume of the freeze-up,the channel storage and the times of ice dam and ice jam are shorted;and the frequency of frozen-free years increases.
Analysis of benefit of water diversion from Yangtze River to Taihu lake:Case study in Huzhou city
WU Hao-yun, DIAO Xun-di, ZENG Sai-xing
2008, 19(6): 888-892.
Abstract:
This paper is focused on the project of water diversion from Yangtze River to Taihu basin (WDYRTB) which significantly improves water environment in Huzhou city and brings the region huge economic benefits.Firstly, water supply effects on industries and residents' living are analyzed by useing the partition coeff icient method.Then, a grey relat ion technique is adopted to show the relationship between water use and industrial development in Huzhou, which proves the rationality of partition coefficient method.The results indicate that the effect of WOYRTB on the economic efficiency of the tertiary industry of Huzhou city is the highest, while that on its industry is the lowest.
Progress in study of glacier hydrological model
QING Wen-wu, CHEN Ren-sheng, LIU Shi-yin
2008, 19(6): 893-902.
Abstract:
The evaluation of the effects of glacier meltwater to Arid Area/regional water resources management,sea-level rising and glaciers natural disaster prevention are very important in the wake of global warming.This paper reviews the processes in glacier hydrological model in term of runoff generation model and runoff concentration rmdel,analyaes the runoff generation mode from two rmst widely ablation model (the meteorological factors statistical rmdel and the energy balance model),and enlarges on the runoff concentration model from three sub-models:the surface routing sub-model,the englacial hydrology submodel and the sub-glacial hydrology sub-rmdel.It is shown that the ablation model has become mature relatively,whereas the runoff concentration model is still at the exploration stage.The last part of this paper suggests the further research on constructing the distributed glacier hydrological physical models which suit to different scale and styles of glaciers and contain glacier movement information.
Development in embankment dam break simulation and water flow simulation
CHEN Sheng-shui, ZHONG Qi-ming, TAO Jian-ji
2008, 19(6): 903-910.
Abstract:
This article summarizes and evaluates the updated research on the breaching simulation technology of embankment dams,and puts forward Mme proposals for future research in this regard,including the analysis and evaluation approaches to the possibility of dam breach of various dam types,the undertaking of the centrifugal rmdel experiments on the dam breach of different types,the focus on the failure mechanism and the process of breach development due to different hazard factors,and the experimental studies carried out on the piping development process so as to open out changing flow transition from orifice to weir.Since the streamline curvature of the dam-breaching flow is steep,the flow is rmstly ultra-critically unsteady and the gradation range of the grain size of the dam building material is quite wide,etc.The large-scale hydraulic model experiments on dam breach should be conducted out,and for different dam types,the in-depth studies should be done alms on the breach outflow process,the sediment transport and the flood ewlvement at the downstream river course.