• 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

2016 Vol. 27, No. 1

Display Method:
A conceptual model of deposition and erosion of mid-channel bar head zone in anabranching river
LI Zhiwei, LI Yanfu, WANG Zhaoyin, HU Shixiong
2016, 27(1): 1-10. doi: 10.14042/j.cnki.32.1309.2016.01.001
Abstract:
Head zone of mid-channel bar is a dynamic shoal of water-sediment diversion and alternative erosion-deposition in anabranching river. Erosion-deposition process in bar head relates to water-sediment supply and local topographic condition. Through the geometric generalization of the mid-channel bar head(i.e. longitudinal upslope and lateral downslope), a conceptual model of bedload transport on the bar head is derived using the concept of upslope facilitating deposition and lateral downslope dividing sediment, meanwhile to obtain a critical discharge formula of the erosion-deposition transition. Along with increasing upstream discharge, the deposition rate in bar head increases first up to the maximum value and then gradually decreases, until approaching the critical discharge, and eventually occurring erosion. The deposition rate in the bar head is proportional to the longitudinal channel gradient and bed sediment diameter, inversely proportional to lateral gradient, upslope and downslope. If other conditions are the same, the shape of bar head is more asymmetric with smaller sediment load supply, more beneficial to the erosion. The critical discharge in the Tianxingzhou Island head of Wuhan reach in the middle Yangtze River predicted by this model is roughly in agreement with the hydrological observation. Nevertheless, the Tianxingzhou Island head still occurs to the deposition when the flood discharge surpasses the critical discharge. To this particularity, this study presents a new explanation that the regulation project(i.e. revetment) in the Tianxingzhou Island head plays a pivotal role on resisting the erosion and facilitating the sedimentation in the higher discharge condition.
Runoff spatial difference of small-scale in Huangnan, Qinghai province and its cause
DUAN Shuiqiang
2016, 27(1): 11-21. doi: 10.14042/j.cnki.32.1309.2016.01.002
Abstract:
Meso-and large-scale hydrological measurements cannot indicate the spatial difference of small watershed. For exploring the spatial difference of small-scale runoff, the fifty rivers in Huangnan, Qinghai with the sampled area in 10-100 km2 are measured on August 14 to 23, 2013. Moreover, the temporal upscaling are also conducted. The results show that the differences of daily discharge modulus could be 20 times higher. It could be more than 4 times even for the regions with similar precipitation. We find the runoff synchronicity in normal season for 3 stations with meso-scale measurements. Based on this character, the daily runoff properity can be deduced to annual time scale. The precipitation and slope could play a dominant role in the spatial difference of small-scale runoff. The reconstructed precipitation, precipitation loss and slope runoff model in this study can provide a useful tool in spatial scale conversion and accuracy improvement of hydrological analysis.
Cross-section characteristics and hydraulic geometry of different erosion gullies on slopes
ZHAO Chunhong, GAO Jian'en
2016, 27(1): 22-30. doi: 10.14042/j.cnki.32.1309.2016.01.003
Abstract:
Gully erosion is one important cause of soil and water loss on slopes, and research on gully morphology is very necessary for understanding principles governing gully erosion and estimating sediment transport. The cross-section characteristics and hydraulic geometry of different erosion gullies on bare sloping land with loamy soil were studied through the collation and analysis of approximate 35 field data sets in China and abroad, and the criteria used to distinguish the erosion gullies were also given. Results showed that the width to depth ratio(ζ) gradually decreased with the development of erosion gullies, and the suitable range of ζ for rills, ephemeral gullies, gullies and streams were 5-17, 2-5, 0.4-1.8 and 0.1-0.6, respectively. The types of loamy soil also affected the ζ value for the same erosion form, and ζ increased as soil particle size increased. Different erosion gullies had different hydraulic geometry indices, and the exponents β1, β2 and β3 were 0.3, 0.4 and 0.3 for rills, respectively; and correspondingly 0.4, 0.4 and 0.2 for ephemeral gullies and gullies; and 0.5, 0.4 and 0.1 for stream. Preliminary validation of the criteria indicated that they could be used to distinguish the different erosion gullies.
Feasibility of applying intermittent irrigation on solute leaching
PENG Zhenyang, WU Jingwei, HUANG Jiesheng
2016, 27(1): 31-39. doi: 10.14042/j.cnki.32.1309.2016.01.004
Abstract:
In order to compare leaching efficiencies of continuous and intermittent irrigations, the HYDRUS-1D dual-porosity model was applied to simulate water and salt movement in soils under difference schemes of irrigation. Results showed that there was a critical depth above which intermittent irrigation would result in higher salt leaching efficiency. Simulations of sandy soils showed that when total irrigation amount was 20 cm, critical depth would decline from more than 60 cm to 0 cm as potential evaporation rate increased from 0 mm/d to 6 mm/d; but it would rise from 20 cm to almost 80 cm as total irrigation amount increased from 10 cm to 40 cm when potential evaporation rate was fixed to be 2 mm/d. Generally, soils with higher water conductivity, higher porosity of micro-pores and lower exchange rate of water and solute between micro and macro pores held higher critical depth, and simulations of sandy, loamy sandy, loamy, clayey loamy and clayey soils indicated that sandy soils were more likely to hold higher critical depth. When total irrigation amount was 30 cm and potential evaporation rate was 2 mm/d, critical depth of clay and sandy soil were 56 cm and more than 100 cm, respectively. In conclusion, there is no universal answer on whether intermittent irrigation would promote leaching efficiency, but critical depth could explain former contradict conclusions on this problem.
Effects of soil additive on soil-water characteristic curve and soil shrinkage
XING Xuguang, LIU Ye, MA Xiaoyi
2016, 27(1): 40-48. doi: 10.14042/j.cnki.32.1309.2016.01.005
Abstract:
To explore the effects of additives on water retention and soil shrinkage characteristics, the experimental soil was mixed with the three types of additives(wheat strew, wheat husk and plant dreg), respectively. The soil water characteristic curves were measured by a centrifuge method, with water retention and soil shrinkage characteristic quantitatively evaluated. The results indicated there were few differences in the types of soil water characteristic curves of all treatments, and van Genuchten model was suitable for the curve fitting. Besides to increasing soil density and soil moisture, the three additives could strengthen water-retaining capacity, ranking in the order that plant dreg >wheat straw >wheat husk >pure soil. Furthermore, axial shrinkage occurred during dehydration, with the three-line model suitable for soil shrinkage curve fitting. A logarithmic function and a Logistic function were found in the relationship between suction and soil moisture, and soil linear ratio, respectively. Finally, the soil shrinkage was ranked in the order that wheat husk
Experimental study on the characteristics of longitudinal oscillating grid turbulence
LI Wenjie, LIU Hua, YANG Shengfa, WANG Tao, ZHANG Peng
2016, 27(1): 49-56. doi: 10.14042/j.cnki.32.1309.2016.01.006
Abstract:
Oscillating grid turbulence is an efficient way of studying complex turbulence and mass transport, while the turbulence generated by the existing vertical oscillating grid systems is quite different from the natural turbulence. A large scale grid turbulence experiment system is established, the grids conduct longitudinal oscillating rather than the traditional vertical oscillating, and the Particle Image Velocimetry is used to measure the flow fields. Tests of the instantaneous flow velocities show that the turbulence generated by this system has strong randomness and statistical regularity. All the longitudinal and vertical root mean square velocities vary rapidly near the grids, and tend to be stable at the middle of the grids. The longitudinal root mean square velocities are larger than the vertical values, and the ratio is about 1.5-2.0, which is close to the natural open channel flow. The fluctuation of the Reynolds stress near the grids is relatively large and decreases with the increasing distance from the grid, the Reynolds stress is about zero at the middle of the grids. The integral time and length scales near the grids are the smallest and increase linearly with the increasing distance from the grids, reaching the maximum at the middle of the grids. The flow velocity spectra obeys the Kolmogorov-5/3 theory. The statistical characteristics of the turbulence generated by this system are consistent with the traditional vertical oscillating grid turbulence, but the longitudinal and vertical turbulent intensities are more close to the natural open channel flow, laying the foundation for the studies of sediment and pollutant transports.
Dynamic mechanism of freshwater extension from the north channel to the north branch in the Changjiang Estuary in dry seasons
LI Lu, ZHU Jianrong
2016, 27(1): 57-69. doi: 10.14042/j.cnki.32.1309.2016.01.007
Abstract:
According to the field data collected in the Changjiang Estuary in December 2011 and January 2012, there was a freshwater extension from the North Channel(NC) to the mouth and lower reaches of the North Branch(NB) where the water salinity was decreased during spring and the subsequent middle tides. However, the phenomenon was absent during the neap tides and subsequent middle tides. To reveal the origin of the freshwater in the lower reaches of the NB, We employed the well validated 3-D numerical model to reproduce the observed phenomenon. The numerical experiments were conducted and the freshwater flux decomposing method was used to investigate the underlying dynamic mechanism of the freshwater extension. We found that the freshwater in the NC extends to the NB mainly through its northern outlet(NONC) and neighboring shoals during spring and the subsequent middle tides due to the Lagrangian transports. Deepening of NONC facilitated the freshwater extension, and hindered the saltwater intrusion into the NB. In the contrast, the high-speed northerly winds would restrict the freshwater extension, while assist the saltwater intrusion into the NB.
Analysis of errors in finite analytic numerical simulation of flow in unsaturated zone
ZHANG Zaiyong, WANG Wenke, CHEN Li, WANG Zhoufeng, DUAN Lei, AN Kedong
2016, 27(1): 70-80. doi: 10.14042/j.cnki.32.1309.2016.01.008
Abstract:
Numerical methods are often used to solve Richards' equation due to the nonlinearity of the equation. Since Finite Analytic Method(FAM) can better keep the original physical properties of the Richards' equation, it has been widely used in the field of environmental and agricultural engineering in recent years. Based on different principles, there are two kinds of Finite Analytic Methods, namely local linearization FAM and Kirchhoff transform FAM, to simulate moisture movement in unsaturated zone. To explore the differences of numerical performances between the two kinds of FAMs, we have carried out the following researches:first, an existing analytical solution is used to preliminarily validate the two kinds of FAMs. After that, two numerical experiments are conducted to compare the accuracy of two methods. Finally, observed data are used to validate the Kirchhoff transform FAM. Compared to the local linearization FAM, Kirchhoff transform FAM can better control the calculated error and obtain higher accuracy of numerical solutions. Therefore, this study has important significance to improve the theory of FAM, which is applied to simulate unsaturated flow.
Single alternating density currents during initial impoundment of estuarine reservoirs
GAO Zengwen, XUE Qingmei, LI Yuhao, SUI Yuzhu
2016, 27(1): 81-87. doi: 10.14042/j.cnki.32.1309.2016.01.009
Abstract:
To explore the occurrence and effects of single alternating density currents during initial impoundment of estuarine reservoirs, we conducted flume experiments to simulate the exchange of salts between sloped sediments and water. We monitored the conductivity profiles of sediment porewater and the water overlying the sediments. Thereby, we analyzed the spatio-temporal distribution of salts, and computed the total salt mass per unit area(SPA) of the benthic boundary layer(BBL) in different zones. The results show that the inflows infiltrate and flow through the surface sediment in the shallow zone. The salt concentration of sediment porewater in the shallow zone was significantly lower than that of water in the middle and profundal zones at the same depth. The SPA in the BBL and salt concentration of water near the sediment-water interface in the profundal zone at the zero hour were both the highest among the three zones. These evidences indicate that density currents moving down sloped sediments are generated and then may have resulted in the accumulation of salts in the profundal zone. After the flume is filled with water, SPA in the BBL and salt concentration near the sediment-water interface in the profundal zone rapidly decrease. Salts reach equilibrium quickly between the water in the profundal zone and the porewater of surface sediment in the shallow zone. These facts indicate that the currents originate in the profundal zone and flow into the sediments of the shallow zone. The salts so released from the sediments in the shallow zone eventually go back into the same sediments. To prevent the salts from going back into the sediments and continuing to affect the salinization of the reservoir, the accumulated salty water in the profundal zone should be discharged regularly after the estuarine reservoir is impounded.
Numerical research on multidirectional waves progresses on the coupling model based on the potential theory and OpenFOAM
JI Xinran, LIU Shuxue, Bo T. PAULSEN, Harry B. BINGHAM
2016, 27(1): 88-99. doi: 10.14042/j.cnki.32.1309.2016.01.010
Abstract:
The numerical wave tank based on the potential theory simulates the wave progression and wave-structure interaction quickly, but it is based on the assumption of non-viscous. In reality, viscous effects are always considered at solid boundaries and wave-broken areas. For the viscous numerical wave basin based on solving the Navier-Stokes equation, however, it has the insufficient of large amount of calculation. Currently, the coupling method is used to simulate wave progression to reduce the amount of calculation and enhance the efficiency. In the outer domain, multidirectional irregular waves are generated from potential theory, and in the inner domain, the Navier-Stokes equation is solved in combination the VOF method to track the free surface.
Groundwater environment risk assessment based on stochastic theory
ZHANG Bo, LI Guoxiu, CHENG Pin, SUN Fasheng, WANG Hongyi
2016, 27(1): 100-106. doi: 10.14042/j.cnki.32.1309.2016.01.011
Abstract:
This paper proposed a methodology on the assessment of groundwater environmental risk based on stochastic theory. A rectangular domain was taken as an example, random field of hydraulic conductivity coefficient is produced by Monte Carlo method, and spatially heterogeneous distribution of aquifer parameters is simulated. Subsequently groundwater flow and transport model are established and the pollutants migration in groundwater is calculated. The statistical frequency of pollution events in a large number of random simulations is considered to be convergent to pollution probability in sufficient simulation numbers, that is to say, pollution risk is reflected by pollution probability. The proposed method assumes that model parameters are random variable meeting a certain distribution characteristic, which avoids the arbitrary assessment with deterministic method. The conclusions obtained in this study can provide useful insights for site selection of factory and water source.
Research on the flood for reservoirs engineering management
DING Jing, HE Qingyan, QIN Guanghua, LI Shenqi, ZHANG Zehui
2016, 27(1): 107-115. doi: 10.14042/j.cnki.32.1309.2016.01.012
Abstract:
The manage-flood, a new concept, is firstly proposed for reservoirs engineering management, and compared with the design-flood. The same and differences between the two kind floods have been analyzed in detail. Two standards for judging the rationality of the manage-flood has been proposed in this paper, one is about such conditions that are satisfied to some management demands, and the other is about flood control safety that is satisfied to the standards. This paper summarized two kinds of analysis methods about the manage-flood. One method is based on the maximum of seasonal flood, and the other based on the maximum of the annual flood. The two methods have respective advantages and disadvantages. The results of the former can't conform completely to the flood control standards while the former has lower requirements for observed data. The results of the later can conform the flood control standards but the later has higher requirements for observed data and no application experiences.
Single-multi-objective operation models and its application on the regulation of water and sediment by cascade reservoirs
BAI Tao, KAN Yanbin, CHANG Jianxia, YUAN Meng
2016, 27(1): 116-127. doi: 10.14042/j.cnki.32.1309.2016.01.013
Abstract:
The regulation of water and sediment in the Upper Yellow River is studied in this paper. To relieve the secondary suspended river that has formed in Inner Mongolia, desert valley reaches in the Upper Yellow River were studied and Longyangxia and Liujiaxia cascade reservoirs were chosen as subjects. Single objective models of sediment discharge maximization and generated energy maximization and a multi objective model were established, and solved by self-iteration simulation algorithm, successive approximation dynamic programming(DPSA), and an improved non-dominated sorting genetic algorithm(NSGA), respectively. Then initial schemes, routine schemes, optimization schemes, and joint optimization operation schemes were set. The results demonstrated that the total scouring sediment of joint optimization schemes was 38 million tons, and power generation of the cascade was 14.8 billion kW·h, with a small loss of power generation in exchange for a substantial increases in sediment. This indicated the great effort required for sediment regulation and the joint operation schemes was recommended as the best option. The results quantified the water and sediment regulation effects and transformation law between objectives are shown. Moreover, the achievements provide a basis for decisions regarding the regulation of water and sediment in the Upper Yellow River. They may have important applications and practical significance in this type of regulation.
Study of real-time scheduling of reservoir group of supply and water diversion systems
SUN Wanguang, LI Chengzhen, JIANG Biao, LIU Yingfei
2016, 27(1): 128-138. doi: 10.14042/j.cnki.32.1309.2016.01.014
Abstract:
Based on the complex reservoir group of supply and water diversion systems in Dalian, the author advances the framework of a system of real-time scheduling and a coupling structure pattern. This paper considers "total amount of control, coupling nested, multidimensional decision-making, real-time correction" as the core of real-time scheduling process. In the aspect of runoff forecasting, this paper proposes the long-term inflow runoff forecast methods of reservoir group of supply and water diversion systems based on transcendental probability, combined with mid-GFS numerical prediction technology for rolling forecast incoming runoff during the different periods. In terms of a scheduling model, this paper uses the new method based on dynamic programming and conventional modeling to provide a reference for scheduling. A case study shows that this real-time scheduling system implements rolling forecast and a rolling scheduling, which proves that the system can be implemented in real time. In the real-time dispatching system, the macro total control is combined with the local adjustment of the scheduling objective and coupled with the scheduling decisions related to nested features with different time scales, thereby proving the applicability of the system. This result has important reference value for similar systems for real-time scheduling.
Satellite retrieval of important ocean hydrological parameters:an overview
WU Guiping, LIU Yuanbo
2016, 27(1): 139-151. doi: 10.14042/j.cnki.32.1309.2016.01.015
Abstract:
The ocean, which covers 71 percent of the Earth's surface, is a fundamental component of the global water cycle. Accurately monitoring the spatial and temporal dynamics of ocean hydro-physical parameters is important for comprehensive understanding of the global water cycle and the effective management of ocean water resources. Ocean remote sensing is a new and advanced space-based technique for estimating spatio-temporally distributed hydro-physical parameters. With five-decades of aerospace satellite sensors development, remote sensing approaches to retrieving ocean hydro-physical parameters appear mature. This paper briefly describes the principles of and retrieval algorithms for the main ocean hydro-physical parameters of Sea Surface Height(SSH), Sea Depth(SD), Sea Surface Current(SSC) and Water Volume Variation(WVV) using optical, passive-microwave and active-microwave remote sensing or combinations thereof. For each ocean hydro-physical parameter, the deficiencies of a single satellite sensor algorithm can be alleviated with the combined use of multi-sensors. Additionally, with the improvement of retrieval techniques, several regional and global hydro-physical parameter datasets have been generated. Hence, this paper also briefly describes the main datasets and their applications. Furthermore, to improve the retrieval accuracy of each hydro-physical parameter, the combination of observations from different sensors is a promising approach. As a result of international efforts, several new satellites are also scheduled to be launched into space, for example, the joint CNES-NASA satellite project SWOT(launch date in 2020) and China's second space lab, Tiangong-2(launch date in 2016). These satellites will greatly improve our ability to monitor the spatial and temporal dynamics of ocean hydro-physical parameters.
Discussion of the theory of computational river dynamics
HEI Pengfei, JIA Dongdong, YE Yuntao, ZHOU Gang, HU Dechao
2016, 27(1): 152-164. doi: 10.14042/j.cnki.32.1309.2016.01.016
Abstract:
Computational river dynamics(CRD) has been developing very fast after the use of the numerical model during the past 50 years. It is of great significance to systematically organize the theory system of the CRD. CRD is mainly used to study the spatial and time variation of the river dynamics. The computational fluid dynamics(CFD),the computational soil mechanics(CSM) and the traditional river mechanics(TRM) are creatively used in CRD. But this is not simple or direct use. The main problem comes from the complex interaction in the multiphase and the multi-scale of the river system. Many new river dynamics model and the numerical technics are created in the processes that the problem is solved. However, all these technics are not systematically organized and analyzed. In this paper, all these theories are systematically organized and analyzed based on CFD and CSM. It is easily to decide the correction, complexity, application feasibility of the different models, which is helpful to choose the model when used in practice and decide the direction of development of the model.