• 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. 1

Display Method:
Effects on flow and sediment in the upper Yellow River by operation of Longyangxia Reservior and Liujiaxia Reservoir
YAO Wenyi, HOU Suzhen, DING Yun
2017, 28(1): 1-13. doi: 10.14042/j.cnki.32.1309.2017.01.001
Abstract:
The regulation mechanism of Longyangxia and Liujiaxia Reservoir on runoff and sediment process is one of the key scientific problems to recognize flow and sediment variation in the Yellow River and optimize the reservoir operation modes. According to the located-observation data of water and sediment in Longyangxia and Liujiaxia Reservoirs, this paper analyzes the regulation and effect of reservoir to runoff and sediment process and reveals the controlling mechanism for the relationship between water and sediment. The main understandings achieved are:① The regulation of large reservoir operation on runoff sediment is related to the operation mode of the reservoir. The pluriennial regulation of Longyangxia Reservoir results in the linear regulation of runoff and nonlinear regulation of sediment transport. The incomplete annual regulation of Liujiaxia Reservoir results in both linear regulation of runoff and sediment; ② Reservoir operation on the Regulation of runoff and sediment has a strong disturbance to the downstream water and sediment relation. It broke the sediment law under natural conditions of the river formed by long-term automatically adjustment and changed the constitutive relation of runoff sediment; ③ The effects of large reservoir operation on the dynamic mechanism for the relationship of water and sediment regulation mainly reflect in adjusting the dynamic equilibrium conditions of sediment-laden flow in which the shear stress decreased in the process of flood propagation. It makes the critical Froude number increase, resulting in the sediment-laden flow by siltation to increase gradient ratio to meet the critical water shear stress requirements of the Froude number state and reach the steady state of sediment-laden flow to stress the relationship between water and sediment change accordingly.
Generalized water efficiency and strategic implications for food security and water management: a case study of grain production in China
CAO Xinchun, SHAO Guangcheng, WANG Xiaojun, WANG Zhenchang, HE Xin, YANG Chenyu
2017, 28(1): 14-21. doi: 10.14042/j.cnki.32.1309.2017.01.002
Abstract:
An index, generalized water efficiency (Eg), for the effective utilization rate of blue-green water evaluation was established in this paper. Eg in grain production for 31 provinces of China during 1998-2010 were calculated. Then temporal-spatial patterns and attribution analysis of Eg in China were explored and conducted by using spatial autocorrelation and path analysis methods, respectively. The results show that, national value of Eg was estimated to be 0.588 in 1998-2010 and the index increased slightly in most of the provinces. Spatial autocorrelation analysis results shows, provinces with resemble Eg value shown significant aggregation. Regions with high Eg values are gathered in Western China while ones with lower Eg distributed in Southeast China; and the global and local spatial aggregation showed decreasing trends over time. Eg was affected strongly by regional agricultural production management level, while the climate and economic conditions had less influence on the effective rate of blue-green water resources. Making a general survey of provincial Eg, water productivity (Pw), water stress index (WSI) and grain production ability, southwest provinces may expand grain production scale in order to play the advantage of high Eg, and major grain producing areas of Northeast China should take measures to raise Eg to ensure food security and sustainable utilization of water resources. The results of this report can provide reference for the development of national water efficiency in agriculture and food production and water resources management strategy.
Dynamic patterns of change in marshes in the Sanjiang Plain and their influential factors
LIU Jiping, DU Baojia, SHENG Lianxi, TIAN Xuezhi
2017, 28(1): 22-31. doi: 10.14042/j.cnki.32.1309.2017.01.003
Abstract:
To explore patterns of dynamic change in a region in which severe changes to wetlands have occurred, we studied patterns of change among marshes in the Sanjiang Plain between 1954 and 2010 using remote sensing and GIS combined with Geo-information Tupu and spatial autocorrelation methods. Marsh area within the Sanjiang Plain gradually decreased between 1954 and 2010, losing around 88.7% of its total area. The number of wetland patches within the plain increased at first and then decreased slightly. The spatial clustering of marshes in the region also decreased gradually from concentrated to sporadic distribution. Additionally, analysis of the results determined that less rainfall, higher temperatures, and a decrease in runoff were main contributors to the decrease in the Sanjiang Plain marsh area. Geography and elevation also affected the degree of marsh area loss; marshes at an elevation of 20-80 m above sea level experienced the most dramatic decline. Decreases in marsh area in the Sanjiang plain also appear to be affected by agricultural development, settlement construction, wetland protection policies and the construction of reserves as well as encroaching residential areas. The degree of marsh area loss appears to increase exponentially according to distance from protected areas:the closer the marsh area is to a protected area, the greater the loss will be.
Spatial variability of permafrost soil-moisture on the slope of the Qinghai-Tibet Plateau
CAO Wei, SHENG Yu, WU Jichun, LI Jing, WANG Shengting
2017, 28(1): 32-40. doi: 10.14042/j.cnki.32.1309.2017.01.004
Abstract:
Permafrost degradation and its freezing-thawing process affect the physical, chemical and biological processes of ecological and hydrological systems in cold regions. In particular, the movement of water in frozen soil is the most important carrier or the main form of migration-transformation of matter and energy in each surface layer in cold regions. Thus, the movement of water in frozen soil is one of the primary forces driving water-resources deterioration and ecological-function degradation. One of the key problems is to reveal the spatial and temporal variability of soil moisture movement and its main controlling factors in permafrost regions. In the Qinghai-Tibet Plateau, the occurrence of permafrost is complex due to different terrain features. Therefore, the spatial variability of the permafrost soil-moisture is more significant. Thus, we explore the spatial variability and its main controlling factors of permafrost soil-moisture on the northern-slope of the Bayan Har Mountains in the Qinghai-Tibet Plateau. The method of classification and regression tree (CART) is adopted to identify the main controlling factors influencing the soil moisture movement. Additionally, the relationships between soil moisture and environmental factors are revealed by the use of canonical correspondence analysis (CCA). The results show the following:① This greatly enhances the horizontal flow in the freezing period due to the terrain slope and the freezing-thawing process. Vertical migration is the main form of soil moisture movement, and it causes the soil-moisture content in the up-slope to be higher than that in the down-slope. In contrast, the soil-moisture content in the up-slope is lower than that in the down-slope during the melting period. ② The main environmental factors that affect the slope-permafrost soil-moisture are elevation, soil texture, soil temperature and vegetation coverage. However, there are differences in the impact factors of the soil moisture in different freezing-thawing stages. The main factors are elevation, soil texture and soil temperature in the freezing stage, with relative contribution rates of 19.97%, 19.45% and 9.56%, respectively. In the melting stage, the main factors are elevation, vegetation coverage and soil texture, with relative contribution rates of 37.4%, 14.9% and 10.7%, respectively. ③ The main factors that affect the slope-permafrost soil-moisture at the shallow depth of 0-20 cm are slope, elevation and vegetation coverage, with correlation coefficients of 0.941 2, 0.903 9 and 0.563 1, respectively. At the middle and lower depths, the main factors influencing the soil moisture are complex.
Spatial distribution of riparian soil phosphorus and its response to hydrologic process
QIAN Jin, SHEN Mengmeng, WANG Peifang, WANG Chao, HOU Jun, LI Kun, LIU Jingjing
2017, 28(1): 41-48. doi: 10.14042/j.cnki.32.1309.2017.01.005
Abstract:
The contents of total phosphorus (TP) and dissolved phosphorus (DTP) in soil sections of Wuxidang Riparian zone (a typical agricultural riparian zone of Taihu Area), rainfall, river water level and groundwater level were monitored and spatial distributions of TP and DTP and the influences of hydrological processes on it at high flow year (2014) were discussed. Experimental results indicated:① Soil TP and DTP firstly increased and then decreased from far-shore to near-shore in the horizontal direction and soil TP and DTP decreased with the increase of the soil depth in the vertical direction. ② River water levels in different months were all lower than the groundwater levels and river water recharged ground water. The temporal charge rules of river water level and groundwater level were similar to that of rainfall, but with rear stagnation. ③ Rainfall is the main driving force of soil water movement. Rainfall, river level and groundwater level had significantly different influences on the spatial distribution of phosphorus in the soil of riparian zone.
Modeling and design on joint distribution of precipitation and tide in the coastal city
TU Xinjun, DU Yiliang, CHEN Xiaohong, CHAI Yuanyuan, QING ying
2017, 28(1): 49-58. doi: 10.14042/j.cnki.32.1309.2017.01.006
Abstract:
Instream flood in a coastal city usually occurs under the influence of heavy rain and high tidal level. Thus, modeling and design of joint distribution of precipitation and tide require increased attention. With Xixianghe River basin of Shenzhen city, Southern China, used as a case, 24-hour data of heavy rain and comparative daily high tidal level are used for two sampling methods, namely, annual maximum (AM) and peaks over threshold (POT). The joint distribution model of precipitation and tide is established by using Copula functions. In this model, the difference between the traditional and second return periods of joint distribution of precipitation and tide is analyzed. The pair values of precipitation and tide are investigated according to two optimally designed methods, namely, equalized frequency method and most-likely weight function. Results show that the generalized normal distribution (GNO) is optimally selected to model the marginal distribution of precipitation and tide, but the differences of model parameters in precipitation are remarkable. Although precipitation and tide exhibit a weak positive dependence, Archimedean Copulas can well model their joint distribution, and the Gumbel-Hougaard Copula is selected as the optimal bivariate model. According to the equalized frequency method, the pair values of precipitation and tide designed by the second return period are greater than those designed by the traditional return period, and those designed by the POT series are greater than those designed by the AM series. However, the designed values of tide level are greater when associated with lower precipitation on the basis of the most-likely weight function. Provided that the sampling method, the joint distribution model, and the type of joint return period are confirmed, a reciprocal situation for a pair of designed values of precipitation and tide is manifested for given joint return periods, that is, a greater designed value of precipitation corresponds to a smaller designed value of tide, and vice versa. In ensuring a secure engineering design against flood disasters due to heavy rain and high tidal level in the coastal city, the sampling of POT and the bivariable design of the second return period are safer than those of AM and the traditional return period, respectively.
Interpolated variance estimator for uncertainty of discharge measurement
BAI Zhixu, HUANG Yan, XU Yueping
2017, 28(1): 59-66. doi: 10.14042/j.cnki.32.1309.2017.01.007
Abstract:
Uncertainty of discharge measurement is often estimated by error tests or empirical and laboratory studies. However, those methods have limitations such as heavy workload and inaccuracy. A method named interpolated variance estimator, which is based on statistical techniques and on-site observations to estimate uncertainty in discharge measurement, is introduced and testified. Measured data at three stations namely Baihe, Xiangyang and Shayang along Hanjiang are analyzed. Besides, Monte Carlo test at Baihe Station is developed to investigate the difference between real error and uncertainty calculated by interpolated variance estimator. The results show that interpolated variance estimator can indicate very well the relationship between uncertainty in discharge measurement and water level. The correlation coefficient of uncertainty and real error derived in the Monte Carlo test is 0.64, and Spearman coefficient of uncertainty and water level is 0.79. Also, uncertainty for high and middle water levels is credible but is overestimated for low water level. These results illustrate that interpolated variance estimator, as a sound statistical method, can be recommended for use in broad applications.
Effect of upward seepage on hydrodynamic characteristics around uniform coarse grains
JIANG Changbo, LIU Yang, DENG Bin, LIU Yizhuang, CHEN Jiayuan
2017, 28(1): 67-75. doi: 10.14042/j.cnki.32.1309.2017.01.008
Abstract:
In order to study the influence of upward seepage on the flow characteristics around uniform coarse grains, we experimentally measured the flow structures around uniform coarse grains under the impact of upward seepage by the technique of Particle Image Velocimetry (PIV), we subsequently analyzed the two-dimensional vertical flow structure around the particle group with different relative upward seepage intensities. The results show that upward seepage decreases the velocity along the mainstream direction and increases the vertical upward velocity around the particle group. With the relative upward seepage intensity increases, both of them become more affected. We also proposed an empirical formula for the longitudinal current velocity distribution under the impact of upward seepage based on the measurements. We finally found that the upward seepage could enhance the turbulence intensity and energy dissipation around the particle group, and the value of vorticity around uniform coarse grains decreases with the increase of relative upward seepage intensity.
Hydraulics analysis of filling and emptying system for evaluating the impact of water level variation on downstream of ship locks
YANG Yuanping, CAO Ying, YANG Li, LI Zhejiang
2017, 28(1): 76-85. doi: 10.14042/j.cnki.32.1309.2017.01.009
Abstract:
To improve hydraulic analysis of filling and emptying system of ship locks that are located in strong tidal areas, a new hydraulic calculation method was developed. This method is based on the theoretical principles of ship lock's filling and emptying, considering the significant variation of water levels downstream of ship locks. This new hydraulic calculation method was used to analyze the Sanbao ship lock in Zhejiang province China, and evaluated the sensitivity of three factors:chamber area, initial water head, descending rate of downstream water level. The results showed that, when comparing to the analysis on constant water levels, the new calculation method revealed shorter filling time, lower peak flow and energy ratio. This study indicates that the new method can provide an appropriate evaluation of filling and emptying system on the impact of water level variation on downstream of ship locks. Findings from this study can be used to support technical design and operation of ship locks in strong tidal sea and estuary.
Mechanisms underlying the dynamic evolution of an open-coast tidal flat-creek system: I: physical model design and tidal creek morphology
GONG Zheng, LYU Tingyu, GENG Liang, ZHOU Zeng, XU Beibei, ZHANG Changkuan
2017, 28(1): 86-95. doi: 10.14042/j.cnki.32.1309.2017.01.010
Abstract:
To deepen the understanding of the dynamics underlying tidal creek evolution, a reduced-scale physical model was established based on the prototype of muddy silt tidal flat-creek system on the central Jiangsu coast. Driven by tidal currents, the evolution of tidal creeks was simulated starting from initial uniform bed level to a dynamic equilibrium state, and the morphology of tidal creeks was analyzed. The results showed that the tidal creek system developed with a sharp and later a smooth increasing rate. Finally, the tidal creek system achieved a dynamic equilibrium state. The development stages of the tidal creek system could be evaluated with two methods. The first index was the ratio between the total length of the tidal creek system in different experimental stages and the total length at the dynamic equilibrium state. The other was the comparison between the elevation-changing rate of tidal creeks and its adjacent tidal flat at each experimental stage. When the dynamic equilibrium state was reached, the number of ordered tidal creeks kept a substantially constant proportion in comparison to the total number of tidal creeks. The width, depth and the width-to-depth ratio of tidal creeks were in line with a lognormal distribution. It showed a power function exists between the width and the width-to-depth ratio, as well as the depth and the width-to-depth ratio.
A numerical model for landslide-generated waves based on two-dimensional shallow water equations
FANG Kezhao, YIN Jing, SUN Jiawen, JIAO Zifeng
2017, 28(1): 96-105. doi: 10.14042/j.cnki.32.1309.2017.01.011
Abstract:
Based on the finite-volume method and a structured mesh system, a numerical model for simulating landslide-generated waves is developed. The governing equations are the two-dimensional nonlinear shallow water (NLSW) equations with the consideration of a dynamic seabed. The central upwind scheme is used to compute the numerical interface flux. The second-order MUSCL method for variables reconstruction, local bed modification and implicit treatment to bottom friction are used to ensure the properties of well-balanced, conservative and non-negative water depth, as well as the ability to deal with the moving shoreline. The second-order Runge-Kutta method with Strong Stability Preserving (SSP) is adopted to perform the time marching. A series of benchmark cases are simulated and the numerical results are compared with the analytical solution, experimental data and numerical results from other models. It is found the present model can simulate the generation, propagation and runup of the landslide-generated waves for the considered cases with reasonable accuracy.
Characteristics of waves in coastal waters of northeast Zhoushan Island during typhoons
YANG Bin, SHI Weiyong, YE Qin, ZHANG Zili, YANG Wankang, SONG Zekun
2017, 28(1): 106-115. doi: 10.14042/j.cnki.32.1309.2017.01.012
Abstract:
To understand the characteristics of waves during the occurrence of typhoons, statistics and spectral variations of waves were investigated through a statistical analysis, and the reason for the variations was determined on the basis of wave data collected at two stations (in deep and shallow waters) in coastal waters of northeast Zhoushan Island during six typhoon occurrences:typhoons Chan-hom, Phanfone, Vongfong, Goni, Soudelor, and Dujuan. The results show that:① The maximum wave height recorded at the two stations during the Chan-hom are higher than that during the other five typhoons. ② The mean wave directions are mainly east and east-south-east in deep waters, and east, east-north-east and northeast in shallow waters during most of typhoons; underwater topography plays a major role in changing wave direction. ③ The paths of typhoons significantly affected the spectra obtained at the two stations; most wave spectra estimated during the Chan-hom, Phanfone, Vongfong, and Goni are double-peaked. During the Soudelor and Dujuan, more unimodal spectral waves were observed at the deep water station, while more multimodal spectral waves were observed at the shallow water station. The research results will be important as reference in the design of coastal structures as well as for disaster prevention and mitigation.
Sea-ice growth and decay model of Bohai Sea based on thermodynamic process
WANG Kun, LIU Pan, JIN Sheng, WANG Nianbin, YU Zhe
2017, 28(1): 116-123. doi: 10.14042/j.cnki.32.1309.2017.01.013
Abstract:
In order to preferably simulate the growth and decay of the ice in the Bohai Sea, based on three-dimensional (3-D) Euler-Lagrangian mode with free water surface vertically-stratified dynamic mesh, the 3-D shallow water equation set was discretized applying unstructured finite volume method with Vertex-Centered pattern. Further, the moving process of water current in the Bohai Sea was simulated. In the background of the above mentioned water dynamic field, the effect of detailed thermodynamic process was introduced, then the freezing process of the Bohai Sea in winter was stimulated, and finally the growth and decay model of ice in this sea area was established. The thermodynamic parameters mainly atmospheric temperature, relative humidity, wind field features, solar radiation, sensible heat flux, and latent heat flux coefficients were systematically investigated. Considering the ice-growth process in the Bohai Sea during 2011/2012-normal ice year as an example, the influence of each thermodynamic parameter on the ice condition and multiple parameters sensitivity were analyzed, and finally model was verified. The results showed that sensible heat and latent heat flux coefficients were the most sensitive parameters affecting the ice condition, i. e., the maximum thickness of sea ice decreased by 15 cm after sensible heat and latent heat flux coefficients were reduced only by 0.000 2. Finally, based on the continuously measured hydrodynamic data and the typical disaster process of sea ice happened during the winter of 2009/2010, the model was verified again, which completely illustrated the higher accuracy, stability, and practicality.
Comparative analysis of water-heat exchange characteristics of the riparian zone downstream of dam in different seasons
LIU Dongsheng, ZHAO Jian, LYU Hui
2017, 28(1): 124-132. doi: 10.14042/j.cnki.32.1309.2017.01.014
Abstract:
To compare hyporheic exchange characteristics and temperature field distributions of the riparian zone following dam release in different seasons, we monitored and analysed the water level and temperature of surface water and groundwater downstream of Xin'anjiang Dam using Darcy's law. Results revealed that lateral exchange flux and river water level were in a counterclockwise "rosette" relationship regardless winter or summer, and the exchange intensity was smaller away from the river. Hyporheic exchange intensity and supply way were distinctly different between winter and summer, where the total exchange volume per unit width near the bank was 55.23 m3(week)and 75.08 m3(week), respectively. In addition, longer lateral exchange length and shorter exchange time were observed in the summer. The temperature field of the riparian zone was significantly affected by low temperature fluctuations, and the vertical direction was characterised as "warmer on the surface and cooler at the bottom" in the summer, while in the winter it was opposite. On the other hand, low temperature propagation distance was relatively larger in the horizontal direction and had obvious zonation in the summer. Therefore, in the process of river ecological management of reservoir downstream, the influence of different seasons should be appropriately considered.
Real-time control strategy for water conveyance of Middle Route Project of South-to-North Water Diversion in China
CAO Yusheng, CHANG Jianxia, HUANG Qiang, CHEN Xiaonan, HUANG Huiyong
2017, 28(1): 133-139. doi: 10.14042/j.cnki.32.1309.2017.01.015
Abstract:
Scientific and reasonable water conveyance control strategy is the basis for ensuring the safe and stable operation of long-distance water diversion projects. According to the control strategy, the goal of water supply plan to each sluice is realized. On the basis of summarizing the research results of the existing water conveyance dispatch control, combining with the actual operation of the dispatch, considering the robustness of target water level control, the constraint of water level drop and the co-ordination of upstream and downstream water regimes, the water conveyance control strategy is improved. The real-time dispatch control strategy based on water flow change and coupling water level-amplitude is put forward. According to the change of flow, the water balance analysis and macro-control are carried out, and the micro-regulation is implemented according to water level and its amplitude. The model is applied to the typical condition of water level adjustment in the channel section of Middle Route Project of South-to-North Water Diversion in China. The water level in front of the control sluice of Fenzhuang River is successfully reduced by 0.5 m according to the requirements through the long water conveyance dispatch of about 1 100 km between the channel headwork and the test section, and other channel sections keep running smoothly. Owing to that the traditional control strategy does not consider the upstream and downstream water regimes and water level drop limit, the water level in front of the control sluice of Fenzhuang River suddenly decreases, and its downstream water level greatly increases during the tests. The validity of the proposed model is verified through case studies.
Overview on research and practice of dam failure emergency evacuation
ZHANG Shichen, WANG Xiaohang, LI Dandan, JI Li
2017, 28(1): 140-148. doi: 10.14042/j.cnki.32.1309.2017.01.016
Abstract:
Technical theory of emergency evacuation during dam failure is crucial for making EPP (Emergency Preparation Plans) and guiding emergency evacuation. Currently, relevant researches mainly focus on analyzing dam failure evacuation factors, overlay analysis on flood, population and transfer paths and life loss statistics. However, due to insufficient basic data of evacuation, ambiguous crossfeed mechanism of ternary coupling of environments, surface features and people and superficial study on warning time, development of dam failure evacuation theory and its practice are quite limited. Through overview of the studies on technical theories of dam failure evacuation and corresponding practice in recent decades, summarizing practices of dam failure emergency evacuation at home and abroad as well as research results in influence factors, progress simulation and EPP evaluation and studying the concepts of warning time and critical warning time, future development of dam failure evacuation is analyzed. To sum up, efforts should be made in reproducing evacuation progress of typical dam failure cases and revealing dynamic characteristics of evacuation system during dam failure on the basis of studies on human behavior and social organization mechanism, thereby to explore quantitative relation between critical warning time and life losses in the case of dam failure and facilitate development and application of technical theories of dam failure evacuation.
Disconnected stream and groundwater interaction: a review
JIN Menggui, XIAN Yang, LIU Yanfeng
2017, 28(1): 149-160. doi: 10.14042/j.cnki.32.1309.2017.01.017
Abstract:
The phenomenon of a stream becoming disconnected from its underlying aquifer commonly occurs in arid and semiarid areas. The interaction between disconnected streams and aquifers is a popular research topic, and over the past few decades, new understanding and methods have emerged. In the present study, we first briefly analyzed the relationship between streams and aquifers. We then reviewed the physical processes and basic principles by which the stream-aquifer system changes from connected to transitional, and subsequently from transitional to fully disconnected, as well as the hydrogeological conditions required for disconnection to occur. For assessing the hydraulic connection between the stream and the aquifer, we synthesized field-based methods based on maximum infiltration rates, critical groundwater tables, or the fluctuations of stream water tables and groundwater tables. The advantages and disadvantages of these methods were analyzed. We also discussed the transient stream-aquifer exchange during disconnection and the effects of heterogeneity on disconnection. We conclude that the basic principles of disconnection are not fully understood. Convenient and reliable methods for assessing the connection status and the effects of heterogeneity on seepage from streams require further investigation in the future.