• 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

2017 Vol. 28, No. 3

Display Method:
Water-sediment movement mechanism in the trough interactive region of compound channels
JI Zuwen, HU Chunhong
2017, 28(3): 321-328. doi: 10.14042/j.cnki.32.1309.2017.03.001
Abstract:
Trough-based compound channels are not only the most common morphology of alluvial rivers, they are also the most important content of river dynamics research. In this paper, based on the generalization experimental data of compound channel and regional characteristics of water-sediment movement, and in combination with four regions of trough-based compound sections, i. e. the main channel equilibrium region, trough interactive region, floodplain equilibrium region and side wall region, the trough interactive region with the most complicated river flow morphology is further divided into two parts, i. e. the logarithmic velocity zone (inner zone) and non-logarithmic velocity zone (external zone). The S-shaped curve describing the animal and plant growth process is introduced so as to propose the determination method of the inner-external zone boundary. Based on the lateral distributional formula of the trough interactive region through linear assumption and integral transform, the calculation equations of sectional average velocity and sediment content in the trough interactive region are given in order to perform comparative analysis on the differences in the velocity and sediment content in different regions. In this paper, the proposed trough region boundary and calculation method of water-sediment distribution will provide technical support for trough planning and governing of compound channels.
Research on bed-load transport formula in the Cheng-Han Reach of the middle Yangtze River
YAO Shiming, WANG Hongyang, MAO Beiping
2017, 28(3): 329-337. doi: 10.14042/j.cnki.32.1309.2017.03.002
Abstract:
After the impoundment of Three Gorges Reservoir, the sediment transport in the reach from Chenglingji to Wuhan of the middle Yangtze River is dominated by the bed load which plays important roles in bed morphological changes, and correspondingly the suspended load discharge is reduced significantly. In this paper, the formula of calculating the bed load transport rate in the above-mentioned reach has been studied. Based on the measured data of Luoshan and Hankou hydrology station, an exponential relationship between sediment discharge of bedload and flow discharge was established, and the transport rates of bedload at these two hydrology stations were calculated by this new relationship day by day. The result shows that the transport rates of bedload at Luoshan and Hankou hydrology station are proportional to the flow discharge with the power of 0.912 78. The multi-annual mean sediment discharges of bedload are 137×104 t and 152×104 t, respectively, which is focused in flood season. Finally, the modified Engelund, Einstein and Yalin formula based on the new relationship according to the measured data were examined. It is shown that the accuracy of each formula has been obviously improved after modification. The modified Yalin formula has the best performances; and then the modified Engelund formula; while the predictions of the modified Einstein formula were not as good as the former two. It is concluded that the modified Yalin formula is the most suitable for calculating the transport rate of bedload of Chenglingji-Wuhan reach, and can be used for the fluvial process analysis and numerical simulation of this reach.
Effect of bed load transport on the energy dissipation of step-pool system
LI Wenzhe, LI Zhiwei, WANG Zhaoyin
2017, 28(3): 338-345. doi: 10.14042/j.cnki.32.1309.2017.03.003
Abstract:
Step-pool system is a typical bed micro-morphology in high gradient mountain rivers, which creates extremely high turbulence intensity and thus dissipates a majority the flow energy. The increase of the bed load transport intensity changed the flow field and reshaped the bedform, thus the energy dissipation effect of the step-pool system changed. A physical model of artificial step-pool system was constructed in a locally regular channel of the upper Wenxia River, a tributary of Han River in the middle Yangtze River. Experiments were conducted to study the flow field and energy dissipation in different flow discharges and bed load transport rates. Experimental results illustrated that the increase of bed load transport intensity significantly changed local flow field in the step and pool. The turbulence intensity on the step increased and the turbulence intensity in the pool decreased sharply. The increase of bed load transport intensity leaded to variation of the energy dissipation distribution. The energy dissipated by bed load transport increased, thus the energy dissipation effect of the bed structure of step-pool system decreased and the pool of the step-pool system was filled up.
Experimental study on velocity profile and turbulence characteristics in open channel contractions
WU Yongyan, CHEN Yongcan, LIU Zhaowei
2017, 28(3): 346-355. doi: 10.14042/j.cnki.32.1309.2017.03.004
Abstract:
Channel contractions are widely used in water diversion projects due to topographical and geological limitations. Short transitions would lead to water surface fluctuations and higher turbulence. To investigate the velocity and turbulence characteristics along transitions of different length, laboratory experiments were carried out using a two-dimensional electromagnetic current meter ACM2-RS. Results show that the longitudinal mean velocity increases along the centerline of the contraction while the longitudinal turbulence intensity decreases, which can be explained by vortex stretching mechanism and linear distortion theory. Influenced by secondary currents, the maximum velocity occurs below the surface. The stronger secondary circulation is, the lower the maximum velocity is located. Contractions of different length affect the velocity profiles and turbulence intensities downstream differently. Shorter contractions lead to higher magnitude of turbulence intensity downstream, while its vertical distribution remains the same in the region away from the bed, which decreases first and then increases with the vertical position going up.
Experimental study on the behavior of coarse particles in two phases flow during water hammer
CAO Bin, ZOU Yi, XIA Jianxin
2017, 28(3): 356-363. doi: 10.14042/j.cnki.32.1309.2017.03.005
Abstract:
Water hammer phenomena within solid-liquid two phases flow may cause serious damage to pipeline and transportation system, the motion characteristics of such unsteady flow are important values for calculating maximum pressure of water hammer. In this research paper, under water hummer condition, with various average flow rate and particle sizes in vertical pipe section, Particle Image Velocimetry (PIV) technique is utilized to study variation law of the velocity distribution of fluid medium and coarse particles as well as variation law of coarse particles followability. The following results are obtained: ① At the different moments of water hammer, the flow rate of coarse particles in the pipe flow is shown as irregular parabolic distribution in the cross section of the pipeline, mainly presented as the velocity of the particles near the bottom of the pipe wall is slightly less than the velocity near the top of the pipe, when the particle size is greater than 1.5 mm and the average flow rate is less than 2.5 m/s, coarse particles exhibit significant sedimentation characteristics; ② The followability of coarse particles is closely related to the force on particles, the change of particle velocity and fluid velocity are important parameters that affect the force on particles; ③ Based on the experimental data, the empirical formula of coarse particle followability coefficient k is obtained under water hammer, and the effects of different parameters such as particle size, pipe diameter, average flow velocity of two-phase flow and time of water hammer on the coherence coefficient of coarse particles were analyzed. The error between the calculated value and the measured value is less than 5%.
Monitoring and analysis of snowline on Tianshan Mountains based on remotely sensed data from 2001 to 2015
LI Shuai, HOU Xiaogang, ZHENG Zhaojun, ZHANG Liancheng, MUZHAPAER Muhtar, XU Zhide
2017, 28(3): 364-372. doi: 10.14042/j.cnki.32.1309.2017.03.006
Abstract:
We monitored the seasonal snowline elevation on Tianshan Mountains and analyzed its changing characteristics and impact factors by adopting the snow cover duration ratio method, based on MOD10A1/MYD10A1, MOD13Q1 and related meteorological data from 2001 to 2015. The results show that: ① The overall snowline on Tianshan Mountains have been on the rise significantly in the recent 15 years, with average elevation of about 3 680 meters, wherein the stability of the snow lines on the northern slope of Tianshan Mountains, Yili River Valley and the southern slope of Tianshan Mountains has weakened successively, the average elevations of which are 3 620, 3 390 and 3 820 meters respectively; the snowline elevation in space shows the latitudinal zonality distribution characteristics of being high in the south and low in the north and high in the east and low in the west. ② On the interannual scale, temperature is the main controlling factor which influences the snowline elevation of Tianshan Mountains, with significant positive correlation, so are the case on the south and north slopes of the Tianshan Mountains, while in Yili River Valley, precipitation is the main controlling factor that influences its change, with significant negative correlation; on the seasonal scale, the temperature in summer and the precipitation in winter are the main controlling factors which influence the snowline elevation, precipitation assumes negative correlation with it, while in areas with higher temperature, the precipitation in summer and autumn can facilitate snow melting, which makes the snowline elevation rise; on the monthly scale, the temperature in July and the precipitation in January are most obvious in affecting it, and there exists a certain lag in response. ③ The snowline elevation of Tianshan Mountains is about 800 meters lower than the zero degree layer, the two have a good positive correlation; snowline elevation shows negative correlation with NDVI, in areas with good vegetation cover, NDVI and snowline elevation in the same year have a good correlation, while in areas with poor vegetation cover, NDVI in the previous year has a good correlation with it.
Regional spatial and seasonal characteristics of soil desiccation on the Loess Plateau
YI Xiaobo, JIA Xiaoxu, SHAO Ming'an, ZHAO Chunlei
2017, 28(3): 373-381. doi: 10.14042/j.cnki.32.1309.2017.03.007
Abstract:
This study was to understand the spatial distribution characteristics of soil desiccation and quantitatively evaluate the soil desiccation conditions within different seasons on the Chinese Loess Plateau. For this purpose, soil water contents of the 0—5 m profile were measured before and after the rainy season in 2013, respectively, along a regional transect (N=86) established from the south to the north. The spatial distribution and variation characteristics of soil desiccation index (ISD) were analyzed using the geostatistical method. Results showed that the spatial pattern of soil desiccation had an obvious latitudinal zonality in the region. The spatial variability of ISD before rainy season was higher than that after rainy season. Dried soil layers were recovered to some extent after supplementation of precipitation after the rainy season. The degree of the recovery was higher in the central part of the region than that of the south and north areas. Furthermore, the difference of ISD distribution characteristics along the soil profiles mainly occurred in the top 0—2.3 m soil layers. This difference was mainly attributed to the limited recharge from rainfall in the shallow layers.
Design storm for mixed level-1 and level-2 urban drainage standards based on the secondary return period
CHEN Zisheng, GAO Shiyou, LI Honghao
2017, 28(3): 382-389. doi: 10.14042/j.cnki.32.1309.2017.03.008
Abstract:
In this paper, we estimated the design storm for mixed level-1 and level-2 urban drain standards according to data of the combination of 1-hour rainstorm and 6-hour rainstorm (R1h-R6h), the combination of 1-hour rainstorm and 12-hour rainstorm(R1h-R12h), and the combination of 1-hour rainstorm and 24-hour rainstorm(R1h-R24h) in Zhuhai city between 1984 and 2015. First, the models of joint probability distribution about different combinations were built using the Archimedean extreme value Copula and the Kendall distribution function. Then, the occurrence probability, "OR" return period, "AND" return period and the secondary return period for each combination were analyzed, and the design storms for each combination were estimated by the method with the maximum occurrence probability. The results are as follows: the cumulative frequency corresponding the secondary return period more accurately represents the risk probabilities of rainstorms of different combinations with specific design frequency; the estimated design storm quantiles of the secondary return period based on return periods with 2-year, 3-year, 5-year, 10-year, 20-year, 50-year and 100-year are between the design storm quantiles of the "OR" return period and these of the "AND" return period, and less than these of the marginal distribution return period, respectively. Compared with the case of design storm quantiles of the marginal distribution return period, the relative error of the R1h-R6h is between 3.1% and 7.1%; that of the combination of R1h-R12h is between 3.3% and 9.3%; that of R1h-R24h is between 3.95% and 12.0%. These provide optimization criterion and guide for the risk management of waterlogging project and the design of drainage pipe, respectively.
Derived moment approach for analyzing the annual runoff frequency and its application
XIONG Lihua, KUANG Yunqi, YU Kunxia, WEN Tianfu
2017, 28(3): 390-397. doi: 10.14042/j.cnki.32.1309.2017.03.009
Abstract:
The current work confirms that the derived moment approach is a suitable replacement for the curve fitting method when runoff data are not readily available. Specifically, annual runoff frequency was estimated using climate variables associated with hydrological processes. The difficulties involved in assessing the annual runoff frequency in the ungauged basins and the solutions to these problems are discussed. Here, 20 basins in Jiangxi Province were examined using the two annual rainfall—runoff models established based on the Schreiber equation and Fu-Zhang equation. Three relevant conclusions were drawn. First, the frequency distributions of annual runoff estimated using the derived moment approach fit the empirically observed frequency of the annual runoff perfectly. Second, the Fu-Zhang model was found to perform better than the Schreiber model when the basins' interannual changes in soil moisture content were not known. Finally, the parameter ω in the Fu-Zhang model was estimated using the inverse distance weight interpolation method through the calibrated value ω of neighboring basins whose runoff data were available.
Estimation of design flood using equivalent reliability method under changing environment
LIANG Zhongmin, HU Yiming, WANG Jun, LI Binquan, YANG Jing
2017, 28(3): 398-405. doi: 10.14042/j.cnki.32.1309.2017.03.010
Abstract:
The intensified impact of climate change and anthropogenic activities has changed the stationary characteristics of the hydrological extreme series, thus posing a challenge on the Traditional Hydrological Frequency Analysis (THFA) method. Therefore, a new theory and approach is required for analyzing non-stationary hydrological frequency. In this paper, further discussions are conducted about the fundamental idea of Equivalent Reliability (ER) approach, and ER application for the design flood estimation under a changing environment has been expanded. The ER approach is expected to address two key issues: ① to estimate the design flood with a given design standard for a project yet to be constructed; ② to adjust the design flood for an already constructed project for its adaptation to the changing conditions. The 59 years of 15-day flood volume series from 1956 to 2014 is used to demonstrate the ER approach, and analysis is conducted for the impact of parameter uncertainty on design flood. The results show that the design flood with a given return period under non-stationary conditions varies with the engineering design lifetime, and the uncertainty of the design flood estimation increases when the engineering design lifetime extends.
Nonstationary hydrologic frequency analysis method considering local trends
WANG Yintang, LI Lingjie, HU Qingfang, LIU Yong, CUI Tingting, WANG Leizhi
2017, 28(3): 406-414. doi: 10.14042/j.cnki.32.1309.2017.03.011
Abstract:
The phenomenon that hydrological series often present nonstationary under changing environments brings huge challenges for the traditional frequency analysis methods based on the independent and identical distribution hypotheses. Thus, it is urgent to investigate new frequency analysis methods for the nonstationary hydrological series. In this paper, a nonstationary hydrological frequency analysis method considering local trend was proposed. The method consists of three main procedures. Firstly, a moving window trend analysis method with identifying capability both for local and global trend was employed. Secondly, time-varying distribution models were established and their parameters were estimated by generalized maximum likelihood method coupled with Bayesian theory. Finally, selecting the optimal model and then design values and confidence intervals were calculated according to the equal reliability principle. The proposed method was applied to the frequency analysis of the annual runoff series gauged at the Hongyashan Reservoir in the Shiyang River basin, Gansu province. Results show that from the perspective of design values and 95% confidence intervals, there are certain difference between the new method and the conventional stationary frequency analysis method, as well as the time-varying distribution method considering the overall trend. This paper reveals that the nonstationary hydrological frequency analysis on the basis of accurately identifying local or overall trend component of the sequence is conducive to estimating design values reasonably.
Groundwater level forecast based on principal component analysis and multivariate time series model
ZHANG Zhanyu, LIANG Zhenhua, FENG Baoping, HUANG Jiwen, WU Dong
2017, 28(3): 415-420. doi: 10.14042/j.cnki.32.1309.2017.03.012
Abstract:
Predication of groundwater level is an important basis for the management of regional water resources. Based on the high randomness and hysteresis characteristics of groundwater in time series, a groundwater level prediction model that is based on principal component analysis and multivariable time series CAR model is built and used for the predication of groundwater level at Dougou irrigation area of Ji'nan. According to the results, the determination coefficient R2 and the Nash-Suttcliffe coefficient Ens of the simulated value and the measured value all reached 0.90 and the above. By taking 2011 as the base year, when precipitation reduces 10%—20%, evaporation and domestic water consumption increases 10%—20% and 273 900—1 370 000 m3 surface water is diverted for agricultural irrigation, the groundwater level at the irrigation area will be maintained at 30.99—31.29 m in 2030, increasing 0.12—0.42 m than that of the base year. Under the background of regional water resources shortage, proper diverting surface water for irrigation and reducing groundwater exploitation can gradually increase the groundwater level at irrigation area and have great significance for the sustainable development of irrigation area and the reasonable utilization of regional water resources.
An exploration on the interoperability of the flood control capacities of cascade reservoir groups in the upper reaches of Yangtze River
ZHOU Xinchun, XU Yinshan, FENG Baofei
2017, 28(3): 421-428. doi: 10.14042/j.cnki.32.1309.2017.03.013
Abstract:
According to the Flood Control Plan of Yangtze River Basin, the total reserved flood control capacity is about 36 billion m3 for large regulating reservoirs with the flood control function, so it is necessary to research scientific and practical flood control and regulation methods. After defining the interoperability of flood control capacities, we explore the interoperability of flood control capacities among reservoir groups in the upper reaches of Yangtze River and propose the reservoir regulation method for flood control on this basis. Taking the cascade reservoirs in the lower reaches of Jinsha River and the Three Gorges Reservoir as an example, we make an analysis of the interoperability ratio of their flood control capacities. The research results show that, for floods in the three typical years, 1981, 1982 and 1998, the interoperability ratio of flood control capacities of Jinsha cascade reservoirs to the Three Gorges Reservoir is within 0.80 to 0.97 and affected by the impounded flood proportions and timing. In the real-time flood control forecast and regulation, the flood may be scientifically and effectively regulated in accordance with the conditions and flood control situations of the reservoir groups, based on the research results of interoperability of flood control capacities and with consideration to the hydrologic prediction and weather forecast.
Force behaviors of circular and square cylinder in internal solitary waves environment: Ⅰ: experimental investigation
WANG Lingling, WANG Yin, WEI Gang, LU Qianyi, XU Jin, TANG Hongwu
2017, 28(3): 429-437. doi: 10.14042/j.cnki.32.1309.2017.03.014
Abstract:
With the development of offshore engineering, increasing attention has been devoted to the safety of the underwater structures, such as the bottom-supported piles of offshore oil drilling platforms and offshore petroleum pipelines. For internal solitary waves (ISWs) exert a neglected influence on the safety of underwater structures, studying ISW forces acting on cylinders is highly significant. Only a few studies have been conducted on ISW forces acting on cylinders, and studies that compare the forces acting on circular and square cylinders in a stratified fluid environment are scarce. Experimental investigations of the forces exerted by ISWs on circular and square cylinders are performed in a stratified fluid tank using a new device to generate ISWs and a measurement system for ISWs loads. Comparisons of ISW force behaviors in the two cylinders are studied at various ISW amplitudes. Results show that the forces exerted on the circular and square cylinders increase with increasing wave amplitudes. At the same wave amplitude, the ISW forces on the square cylinder are larger than those on the circular cylinder. This study provides guidance for cylinder design and safety evaluation in a stratified fluid environment.
Wave breaking simulation by non-hydrostatic numerical model
ZHANG Jingxin
2017, 28(3): 438-444. doi: 10.14042/j.cnki.32.1309.2017.03.015
Abstract:
Wave breaking is one of the key hydrodynamic issues in coastal engineering, and the research on numerical simulations of wave breaking is in the ascendant. Based on the static pressure model, a completely non-hydrostatic model is proposed by introducing the dynamic pressure term and has been successfully applied to the simulation of dispersive water waves. Vertical coordinate transformation approach is adopted to capture the free water surface, which exhibits improved computationally efficiency as compared to the conventional VOF method. However, the vertical coordinate transformation approach cannot simulate large-curvature free surface deformation, i. e., the wave breaking process. Therefore, a model-splitting method is developed to simulate breaking waves, in which the model in the wave breaking zone is divided into a hydrostatic model and a non-hydrostatic model. That is, near the peaks of breaking waves the model is degraded to the hydrostatic model, which persists until the end of wave breaking and thereafter reverts to the dynamic pressure model. In this paper, the applicability of the model-splitting method and its accuracy for the simulation of wave breaking process are validated against canonical cases. Since this method has not introduced any new generalized model for wave breaking process, it has high computational efficiency and can be applied to the simulation of large-scale wave deformation, fragmentation and propagation in the coastal zone.
Experimental study of mean discharge of wave overtopping on vertical seawall under the condition of breaking waves
LI Xiaoliang
2017, 28(3): 445-451. doi: 10.14042/j.cnki.32.1309.2017.03.016
Abstract:
The comparisons show that there are significant differences between the existing research works in aspects of the estimation on the average overtopping discharge of breaking wave on vertical wall and the effect of the impact factors, that to make a reliable choice among the works for engineering application, checks based on the independent experiment become necessary. To this end, systematic checks on the results estimated by the representative works were carried out based on physical model tests of random wave, and the reasons which make the difference between the works were analyzed combined with the investigation to the regulation of the factor's effect. The experiment results that the treatment on the main impact factors, such as the period and the bottom slope ratio, is highly responsible for the marked difference between the works; EurOtop generally makes the significant overestimation, while Goda (2009) is most consistent with the conclusions of current experiment with regard to both the treatment of the impact factors and the results of estimation.
A reviews on irrigation water rebound effect
SONG Jianfeng, WANG Yubao, WU Pute
2017, 28(3): 452-461. doi: 10.14042/j.cnki.32.1309.2017.03.017
Abstract:
Technological methods for improving irrigation efficiency are widely regarded as effective for reducing water use. However, it has not achieved the expected water savings; water use in some areas even increased. This situation implies that the so-called rebound effect may occur, which means the expected water savings are offset by the additional water demand arising from agricultural output increasing. Research on irrigation efficiency improvement's effect on water savings has palpable benefits nowadays. Nevertheless, the literatures on the rebound effect of irrigation water not been reviewed systematically. This paper reviews these literatures from these aspects of the following: a definition of water rebound effect, scale effects of water savings, and the rebound mechanism and magnitude of the water rebound effect. The irrigation water rebound effect needs to be researched further, and cannot be studied with the framework and method for energy rebound effects, due to the measuring complexity of water use, savings and efficiency. Future research areas should focus on the following: ① providing a clarified definition of irrigation water rebound effect, as to distinguish the hydrological and economic rebound, water use and consumption rebounds, and the general rebound and the backfire effects; ② deeply study the mechanism of irrigation water rebound; ③ develop a reasonable method for calculating the irrigation water rebound effect.
Review on the influence of forest canopy on the process of snowfall interception
XIAO Yang, ZHANG Shulan, SONG Guohua
2017, 28(3): 462-471. doi: 10.14042/j.cnki.32.1309.2017.03.018
Abstract:
The processes of snowfall interception by forest canopy, the evaporation or sublimation, release, and melting drip of the intercepted snow significantly affect the hydrological cycle in the forest area of the north globe. Therefore, research is needed to understand the effects of forest canopy on the processes of snowfall interception. Such research would also be important for the understanding of climate change and the management of forests, forest fires, and vegetation succession in areas that experience seasonal snow cover. The mechanisms of snowfall interception and subsequent processes of snow transportation, and methods for measuring these processes, have been widely reviewed previously. However, there is lack of knowledge of the effects of forest stand scale and level process. Here, we propose to use remote sensing and other advanced research methods in studies on snowfall interception to complement the existing research. Key to this future research direction is the consideration of multi-scale, multi-process, and multi-factor interactions.
Analysis of National Key R&D Program of China “high-efficient development and utilization of water resource”
ZHOU Bin
2017, 28(3): 472-478. doi: 10.14042/j.cnki.32.1309.2017.03.019
Abstract:
National Key R&D Program of China "high-efficient development and utilization of water resource" is one of the first batch of programs launched in 2016 after reform of the national science and technology program management. Based on the practical situation of water resources in China and the advances of water science in domestic and overseas, improvement of scientifically supporting water resources security was targeted as the overall purposes of the program, the scientific issues and main tasks to be solved were formulated as well by innovatively designing and layout for whole chain elements. The general framework, scientific goals, main tasks, and the general information of projects application are discussed in the paper. The future advices aiming at the problems existing in the projects application in 2016 and 2017, the possible major tasks in further studies are addressed, which has an important guiding role to strengthen the program management and ensure that the overall objectives are achieved.