• 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

2014 Vol. 25, No. 6

Display Method:
Assessing the applicability of GLDAS monthly precipitation data in China
WANG Wen, WANG Xiaoju, WANG Peng
2014, 25(6): 769-778.
Abstract:
Global Land Data Assimilation System (GLDAS) is an important data source for global change and water cycle research. GLDAS-1 and GLDAS-2 monthly precipitation data during 1979—2012 are compared with Chinese ground-based observations for evaluating their capabilities to detect spatial and temporal changes, and evaluating data quality in terms of correlation coefficient, mean bias error, relative absolute error and root mean square error. The results show that: The quality of GLDAS-1 data sets has a problem of discontinuity, especially serious anomalies in 1996 and poor quality in 2000; the qualities of both GLDAS-1 data and GLDAS-2 data decline during the period from 1979 to 2012 according to their fitness with the observed precipitation data; GLDAS data sets show better quality in eastern China wet areas than in western China arid areas; in terms of correlation and error measures, GLDAS-1 precipitation data are slightly better than GLDAS-2 data (mostly in the period before 1995), but GLDAS-2 data are significantly superior to GLDAS-1 data in the temporal consistency, seasonal stability and their capability to describe temporal variations.
Annual streamflow of Jinghe River basin in northern slope of Tianshan Mountains recorded by tree-ring during 1615—2007
SHANG Huaming, YIN Zifeng, CHEN Zhijun, WEI Wenshou, YUAN Yujiang, CHEN Rongyi
2014, 25(6): 779-788.
Abstract:
Tree-ring width from northern slopes of Tianshan Mountains is of great potential for hydroclimate reconstruction. Tree-ring width data of Picea schrenkiana from two sites which are located at Jinghe River basin were collected and developed into tree-ring width chronologies. Correlation analysis between tree-ring width index and hydrometeorological factors indicates the potential of tree ring width for streamflow reconstruction, and the coefficient between tree-ring width standard chronology and streamflow from last September to current August in Jinghe River hydrological station is 0.612. A linear transfer function is established to reconstruct the annual streamflow during 1615—2007. There are 7 flood years and 11 drought years, and 13 consistent periods and 10 consistent periods during 1615—2007. Multi-taper method (MTM) spectral analysis revealed the cycles of 56.8 a, 6.9 a, 3.8 a, 3.4 a, 2.0—2.1 a above the 99% confidence level. The cycle of 6.9 a, which is accordant with ENSO, indicated the possible influence of large scale ocean-atmosphere pattern on the regional hydroclimate. Furthermore, the significant negative association (P<0.05) between Souther Oscillation Index (SOI) and reconstructed hydrological series also proved this teleconnection pattern. The drought and flood period in Jinghe River is well corresponding with that in Manasi River and Urumqi River, and the wet and dry period in Tianshan Mountains area and Yili region, which indicated the consistency of large-scale circulation background and driving climatic factors of hydroclimate change in northern slopes of Tianshan Mountains.
Runoff error proportionality coefficient correction method based on system response
ZHANG Xiaoqin, LIU Kexin, BAO Weimin, LI Jiajia, LAI Shanzheng
2014, 25(6): 789-796.
Abstract:
To improve the accuracy and stability of the real-time flood forecasting, a new error correction method is introduced. The new method is based on another named runoff error correction based on dynamic system response curve(DSRC). And it is named as runoff error proportionality coefficient correction method based on system response (REPC). In this method, calculated runoff series is divided into some shorter ones according to certain principle. System errors are assumed to occur in each series, and the errors can be expressed by a proportionality coefficient. The proportionality coefficient can be estimated by choosing the appropriate parameters of the model derived from the system response. REPC method, as well as DSRC method, is applied in Tankeng basin. The results indicate that both methods can improve the accuracy of the real-time flood forecasting, but REPC method performs better results with regard to the accuracy, the stability and the range. With the sound physical laws and the long forecasting, the method introduced in this paper is well worthy of further applications.
Experimental study of development and erosion of gravel mid-channel bar
LI Zhiwei, WANG Zhaoyin, LI Wenzhe, ZHANG Chendi, LYU Liqun
2014, 25(6): 797-805.
Abstract:
Mid-channel bars occur in anabranching rivers. Fluvial processes of a mid-channel bar following variation of flow and sediment transportation are studied experimentally, which influences the equilibrium of flow and sediment transport in anabranching channel. The processes of development and erosion of a mid-channel bar were observed and measured under different flow discharges, sediment feeding rates, and with different grain sizes. A simplified model of bar head growth is established to analyze the rate of bar development. Results show that gravel deposition occurred along bar head from the branching point, and the left and right channels became sediment transport channels. There was little sediment deposition at the bar tail. In high flow discharge and low or no incoming sediment load experiments the bar head was firstly scoured and thence, extending scour occurred along the bar body. The sediment removed from the bar head was transported to downstream along the left and right channels, not deposited on the bar tail. Bar head deposition is a dominant process for gravel mid-channel bar growth. The growth rate is a function of sediment load, grain size, bed slope and branching angle.
Distribution and simulation of saturated soil hydraulic conductivity at a slope of northern Loess Plateau
ZHAO Chunlei, SHAO Ming'an, JIA Xiaoxu
2014, 25(6): 806-815.
Abstract:
To provide a theoretical basis for simulating soil hydraulic processes, classical statistics and geo-statistics were used to characterize the spatial distribution of saturated soil hydraulic conductivity (Ks) at a slope scale in the northern Loess Plateau. Furthermore, the first order autoregressive state-space model was applied to simulate the distribution of Ks. The magnitude of Ks variability was moderate according to the coefficient of variation. The degree of spatial dependence was moderate with range of 42 m. Bulk density, sand content, silt content, and clay content were auto-correlated. Cross-correlation existed between Ks and other factors at different lag distance. Bulk density and soil particles were the key factors to affect the spatial distribution of Ks on the sloping land. A combination of bulk density and soil particles was the best to explain the spatial variation of Ks(R2>0.9). The first order autoregressive state-space model is suitable for simulating the Ks distribution at a slope scale.
Micro drip irrigation district environmental impact on soil water and salt transport
ZHOU Heping, WANG Shaoli, WU Xuchun
2014, 25(6): 816-824.
Abstract:
Drip irrigation under mulch is an efficient and water-saving irrigation practice implemented in the arid agricultural areas of China. Based on the micro environments specific to drip irrigation, i.e. "middle of the film", "between the film", "edge of the film" and "outside the film", as well as the 5 960 data collected during 2011—2013 by field contrast test, the relationships between soil level environment, irrigation quota, soil moisture, temperature, evaporation and water-salt movement were established through the Cobb-Douglas model. The results showed that, in arid irrigation areas with strong evaporation and under the combination of plastic film mulching and drip irrigation, soil water and salt migrate horizontally from the "middle of the film" towards the exposed "edge of the film", and vertically from the lower to the upper soil layers, tending to accumulate in the boundary at the "edge of the film". The interaction between temperature and evaporation, especially, drives the movement of soil water and salt at mulching spaces and in bare soils. The research further revealed the directional migration of soil water and salt in the context of drip irrigation under mulch, and can provide a basis for the application of water-salt surface discharge method in soils.
Hydraulic characteristic of overland flow under different vegetation coverage
ZHANG Kuandi, WANG Guangqian, SUN Xiaomin, WANG Junjie
2014, 25(6): 825-834.
Abstract:
Determining hydraulic characteristics of overland flow under the condition of vegetation coverage is a theoretical foundation of studying flow retardation and sand fixation by vegetation. By a simulated vegetation experiment, the variations of hydraulic parameters of overland flow were systematically investigated at ten flow discharges, six slope gradients and five vegetation coverage degrees so as to expect to disclose the inherent law of resistance of vegetation cover for overland flow. Results showed that under the experimental condition, the flow-state indicators increased as the vegetation cover increase; under the same vegetation cover, the slope under the experiment had no apparent influence on it, and the flow regimes mainly ranged from "virtual laminar flow" to transition states, not reaching turbulent state. The overland flow developed from subcritical flow to supercritical flow with increasing slope gradient, but extended in opposite direction with increasing vegetation coverage. Under the condition of vegetation cover, the change law of overland flow resistance and Reynolds number was not the one of monotonical increase or decrease, but was highly related to the vegetation coverage. As Reynolds number increased, the resistance coefficient decreased at low vegetation coverage and however showed a linearly increasing trend at high vegetation coverage. The study is of scientific significance in understanding the mechanisms of regulating slope runoff and sediment yields by vegetation and may provide a scientific basis for the implementation of ecological restoration projects.
Experimental study of bedform-driven hyporheic exchange
CHEN Xiaobing, ZHAO Jian, LI Yingyu, CHEN Li
2014, 25(6): 835-841.
Abstract:
In order to test the bedform impacts on the hyporheic exchange behavior, the tracer NaCl is used to test the hyporheic exchanges under four groups of bedforms in a water-circling flume. Based on the diffusion theory, the impacts of hydrodynamics of water column and permeability of underlying sediments on the hyporheic flow are analyzed. Results show that the hyporheic exchanges can occur on a flat bedform. The exchange rate can be intensified under a more uneven bedform and a higher Reynolds number. Compared to the factor of water depth, the hyporheic exchange rate is much more sensitive to the velocity of the surface water. In addition, the effective diffusion coefficient is proportional to the square of characteristic grain diameter, and has a linear relationship with the streambed hydraulic conductivity. Also, the exchange depth in the flume is found to be proportional to the Re1/2.
A robust data-assimilation model for river network system
CHEN Yifan, CHENG Weiping, XU Qinghua, WAN Xiaoli
2014, 25(6): 842-847.
Abstract:
For improving the accuracy of river network numerical model, this paper developed a data assimilation model based on the theory of least-squares method, which specified real-time observed hydrological data as internal boundary conditions of flood routing model. In order to effectively control correction degrees of state variables and to avoid destroying overly the water balance relationship, a correction weight matrix was introduced, which could control and counterpoise the correction degrees of all measurable state variables. In a simulation example and an application to a real one, it systematically examined and analyzed the real-time correction capability of the present model. The results reveal that the present model is able to carry out data assimilation of river network system efficaciously, improving the accuracy of flood simulation and forecasting.
A 1D-2D coupled mathematical model for numerical simulating of flood routine in flood protected zone
CHEN Wenlong, SONG Lixiang, XING Linghang, ZHANG Wenming, ZHOU Jianzhong
2014, 25(6): 848-855.
Abstract:
A 1D-2D coupled hydrodynamic model is developed by using a lateral linkage for numerical simulating of flood routine in flood protected zone with complex geometries and hydraulic interactions between river and flood protected zone. A Riemann problem based model coupling method is proposed to resolve the problem of no momentum exchange and the uncertainty of discharge coefficient from the traditional coupling method based on the weir equation. Besides, an adaptive time-stepping method is used for the 2D model to trace the time line of the 1D model. Numerical results show that the proposed model can effectively simulate the flood due to dyke-overtopping and dyke-break in the coupled system of river and flood protected zone, thus has bright application prospects.
Hydrology, hydrodynamics, water quality model for impounded rivers: II: Application
CHEN Liangang, SHI Yong, QIAN Xin, JIN Qiu, LAI Xiaozhen, WANG Shuai
2014, 25(6): 856-863.
Abstract:
In order to improve the ability of water environment pre-warning and emergency response on the Huaihe River basin, the Hydrology, Hydrodynamics, and Water Quality Model (DHQM) is developed for the Huaihe Middle River network. The Huaihe DHQM comprises three 1-D parts (Huaihe River stem, Shaying River, and Guohe River) and two 2-D parts (Lutaizi Reach and Bengbuzha Reach). The water quantity and quality series during 2004 and 2008 were used to calibrate and validate the model, respectively. A typical virtual accident scenario was assumed based on the pollution characteristics of the Huaihe River basin. The Huaihe DHQM was applied to analyze the effects of pollution mass on downstream across different combinations of regulation scheme and flow from the Huaihe River stem. After comparing the modeling results of different regulation schemes, the slow release of water from several installments under a low discharge was identified as the optimal emergency scheme that could secure the water quality of Bengbu and minimize the influence of pollution mass on downstream.
The simplified algorithm for the pollution mixing zone in rivers in consideration of the boundary reflection
WU Zhouhu
2014, 25(6): 864-872.
Abstract:
Mathematical deductions proved that the pollutant concentration at location P(x, y) in the bank discharge situation is equal to the one at location Q(x/4,±y/2) in the central discharge (the origin of both is at the discharge point). According to our numerical experiments and curve regression of the results, this paper gives the parameters of the pollutant mixing zone including the coordinates of the maximum length and width and its area, the practical formula for concentration distribution along the river's center line and bank, and the approximate outer boundary curve equation of the pollution mixing zone. The results have great practical value in the calculation of the pollution mixing zone in medium-width rivers and the estimation of the concentration at environmentally sensitive locations. It also provides an accurate, convenient, fast and practical method for engineers.
Water containment risk estimation during interim flooding for high rock-fill dams
ZHANG Chao, HU Zhigen
2014, 25(6): 873-879.
Abstract:
In this paper, a mathematical model is designed to estimate the water containment risk for high rock-fill dams during interim seasonal flooding based on the condition that the water must not flow over the top of the dam, and other stochastic factors such as the level of the floodwater in front of the dam and the high water level during flooding. The characteristics of rock-fill dam construction systems, the number of days each month when the dam is under maintenance, and the stochasticity of the average speed of the increase in water level per day are considered for designing a model to calculate the simulated height for flood prevention during interim flooding. Based on the Monte Carlo method, the created risk model is solved by linking stochastic elements from hydrology, hydropower, and construction. Further, the influence of the controllable construction indicator, which is the minimum average daily rising speed, on the risk rate is researched. The feasibility and effectiveness of the risk model and the calculation method are demonstrated through the analysis of Changheba hydropower station in the Dadu River basin in Sichuan, China.
Surface elevation variation of the Jiangsu mudflats: Field observation
GONG Zheng, JIN Chuang, ZHANG Changkuan, LI Huan, XIN Pei
2014, 25(6): 880-887.
Abstract:
To investigate the characteristics of double-convex cross-shore mudflat profiles, ten benchmarks were set on the intertidal flats in the south of Chuandong River (Yanchen, Jiangsu). The surface elevation of the intertidal flats was monthly measured from September 2012 to November, 2013. Two convex points are found close to the mean high and low tidal levels. The upper intertidal flats are less affected by tidal currents and relatively stable. The elevations of the mudflats located between the mean high and low tidal levels vary considerably during different seasons and appear to be erosive at a year-long scale. The lower intertidal flats are subjected to severe erosion and the associated seaward slope becomes steeper. From the upper to lower mudflat, the cross-shore profile shows a ‘stable—accretional—stable—accretional—erosional’ characteristic with two siltation peaks.
Optimal approaches of integrated flood management and sustainable development in China's flood retention areas
SONG Yuqin, ZHANG Xiaolei
2014, 25(6): 888-896.
Abstract:
The designed floodwater storage frequency and storage pattern are main thresholds for flood management and regional social-economic development in flood retention areas of China's river basins. Under the backgrounds of "Integrated Flood Management" and "Sustainable development", this paper focused on the optimal developing approaches in China's flood retention areas. Based on different designed floodwater storage frequencies in detention areas, 3 development scenarios, as status quo, proportionally wetland restoration and proportionally reservoir-shaping, were first established within 35 years. Meanwhile, multi-objective evaluation index system was built consisting of flood mitigation, social-economic development and ecological benefits. Finally, according to Data Envelopment Analysis (DEA), the optimal approaches for different flood retention areas were identified and discussed. DEA model results indicated that proportionally wetland restoration was the optimal approach for 70% flood retention areas in China and "flood period 50" of designed frequency for floodwater storage was the boundary of various flood retention areas-if the designed floodwater storage frequency of a flood retention area was lower than "flood period 50", proportionally wetland restoration was its optimal developing way, while, if higher than "flood period 50", maintaining its status quo was the optimal way. The research findings could provide valuable suggestions and decision-making support for flood management and sustainable development in flood retention areas.
Water resources demand hierarchy theory and preliminary practice
HOU Baodeng, GAO Erkun, WU Yongxiang, ZHAN Xuzhu, WANG Gaoxu, WU Kai
2014, 25(6): 897-906.
Abstract:
The accurate forecasting of water demand is highly crucial for both economic and social development planning and water supply planning and management. Any very large or small water demand forecasts that are a result of blind predictions will bring different degrees of misdirection to water conservancy planning and water supply project construction and lead to very serious consequences. Therefore, there is a need to predict the different levels of actual water demands from the perspective of the water user. This paper firstly analyzes the connotations and impact factors of water resources demand; then, Maslow's Hierarchy of Needs Theory is introduced and a preliminarily water resources demand hierarchy theory is established; then, the different levels of actual water demands are discussed from the perspectives of life, production and ecology; finally, taking Puer as an example, the demand for water is forecasted from different hierarchies. In 2020, under the water frequency of 50%, 75%, 90% and 95%, the total quantity of the water demand forecast outside a river under the development level is smaller by 28.2%, 22.6%, 22.6% and 18.1% respectively when compared with planning results; while that under the basic level is even smaller. Under the harmonious level, the forecast results are smaller by 1.8%—13.8%. Under the water frequency of 75%, water demands under the development level are overall smaller by about 0.8%—1.7%, almost the same as the forecast results obtained by using the method of integrated water consumption per capita. The results show that the forecast results under different frequencies and different levels are generally smaller than conventional ones, which makes up for the deficiency of the conventional forecasting that is always larger.
Research advances in nighttime transpiration and its eco-hydrological implications
SI Jianhua, FENG Qi, YU Tengfei, ZHAO Chunyan
2014, 25(6): 907-914.
Abstract:
It is generally assumed that transpiration does not occur at night because leaf stomata are opened during the day and closed at night. Nonetheless, there is increasing evidence that the stomata are opening in many species and in a range of habitats at night. Nighttime transpiration rates are typically 5%—15% of daytime rates. This proportion of nighttime transpiration is often highest (30%—60%) in arid desert systems. Control of nighttime transpiration may have considerable complexity, it relates to the different levels control variables. The magnitude of nighttime transpiration with plant genetic factors, it is also affected by abiotic factors, such as vapor pressure difference, wind speed, soil moisture, atmospheric CO2 concentration, soil temperature and so on. Study shows that water vapor pressure deficit is the most important environmental driving factors to nighttime transpiration. Nighttime transpiration has significant implications for water budgets as an inevitable process. It can reduce leaf water potential of plant, contribute to imbalance between predawn leaf water potential and soil water potential, reduce hydraulic redistribution, affect of ecological water balance, enhance nutrient availability, and affect the productivity and growth of plant.
Advances in research on turbulence structure in vegetated open channel flows
YAN Jing, DAI Kun, TANG Hongwu, CHENG Niansheng, CHEN Yang
2014, 25(6): 915-922.
Abstract:
Aquatic plants in natural rivers have important effects on turbulence structure. In the presence of vegetation, river flows become more intensely mixed and their turbulent structures are more complicated. Many studies have been conducted recently to examine turbulence characteristics of vegetated open channel flows, which directly affect the transport of sediment, pollutants and nutrients. This work provides a review of the previous studies in the context of time-average turbulent characteristics, coherent structure, flow regime and relevant factors that influence the turbulence structure in vegetated flows. It is suggested that a combined analysis of field and point information is applied to quantitatively describe the formation and development process of coherent structure, and to explore the turbulence mechanism of vegetated flows for the further study.