• 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

2009 Vol. 20, No. 6

Display Method:
Application of statistical weight matrix method in estimation of regional rainfall
SHAO Yue-hong, ZHANG Wan-chang
2009, 20(6): 755-762.
Abstract:
In terms of the Doppler radar rainfall estimation algorithms, such as the Z-Rrelation, the average calibration, the Kalman filter, the optimum interpolation, the variation, the optimum Kalman filter and the variation Kalman, the regional rainfall are estimated and compared with those interpolated from the observations in the automatic precipitation observatories. The results suggest that the performance of each algorithms mentioned above is not very satisfied. The statistical analyses are applied to the estimated results, and the statistical weight matrix approach is employed to improve the accuracy of the regional rainfall estimations. The results reveal that the precision of the regional rainfall estimation from the average calibration, the Kalman filter, the optimum interpolation, the variation, the optimum Kalman filter and the variation Kalman are evidently superior to those from the Z-Rrelation, and the regional rainfall estimation from the Z-Rrelation shows the evident underestimation. What's more, the results further show that the accuracy of the estimated regional rainfall derived from the statistical weight matrix approach by integrating all individual algorithm mentioned above is evidently higher than that obtained by any individual ones. The quantitative rainfall estimations with the statistical weight matrix approach are very close to the automatic rain-gage network observed either in the spatial distribution or in the location of the intense precipitation centers. The regional precipitation estimation of the statistic weight matrix approach can truly reflect the precipitation status over the ground surface and might be served as a promising conventional method for estimation of the regional rainfall for the studied region.
Characteristics of GPS-retrieved precipitable water vapor in different precipitation types
GUO Jie, LI Guo-ping, HUANG Wen-shi, CHEN Jiao-na, HAO Li-ping, YANG Dong
2009, 20(6): 763-768.
Abstract:
The precipitable water vapor (PWV) data are retrieved from the ground-based Global Positioning System (GPS) observational network together with the automatic weather stations in Chengdu region during the period of August 21, 2007 to November 30, 2008. The GPS-retrieved PWV data are analyzed for diurnal cycle characteristics as well as for different precipitation types including the summer heavy rainfall, the autumn continuous rain and the winter snow-rainfall. The result shows that storms occurred in different seasons correspond the distinct PWV. For example, the summer storms are associated with the change of PWV values from peaks to troughs. The opposite PWV change characteristic to the summer heavy rainfall is found at the end of summers. The result suggests that the change ratio of PWV values before a rainfall event may well indicate the intensity of subsequent heavy rainfalls. Significant variations in PWV ratios during the autumn continuous rain can potentially predicate the beginning or the ending of a rainfall event. The real-time consecutive GPS-retrieved PWV data can thus be used in operational precipitation forecasting.
Analysis of artificial precipitation interception over two meadow species on Qinghai-Tibet Plateau
LI Chun-jie, REN Dong-xing, WANG Gen-xu, HU Hong-chang, LI Tai-bing, LIU Guang-sheng
2009, 20(6): 769-774.
Abstract:
This study examines the interception characteristics during the artificial precipitation experiments over alpine and swamp meadows in a small-sized permafrost catchment Fenghuoshan located in the Qinghai-Tibet Plateau. The interception data under different rainfall intensity conditions were collected during the experiments. The data were analyzed using the statistical methods. The result shows that the canopy interception for alpine meadow can reach a high value of 0.61 mm, while only 0.18 mm is found for swamp meadow. The maximum rates of canopy interceptions for alpine and swamp are 12.4% and 3.8%, respectively. The relationship between the canopy interception and rainfall amount for alpine meadow can be represented by a power function; while a quadratic polynomial relationship is derived for swamp meadow. Such relationship becomes a power function for both meadows if rainfall amount is replaced by rainfall intensity. A linear relationship between the canopy interception and the density of vegetation coverage is also found for both meadows.
Temporal and spatial variation law of reference crop evapotranspiration in Tibet
YANG Yong-hong, ZHANG Zhan-yu, RUAN Xin-jian
2009, 20(6): 775-781.
Abstract:
Based on the meteorological observation data collected by the 38 weather stations in Tibet for several decades before 2006, the daily values of the reference crop evapotranspiration (ET0) are calculated by FAO-56 standard Penman-Monteith formula, and the daily and monthly change law of ET0 over the seven stations is analyzed. The tendency test is conducted on the data of the monthly and annual ET0 using the Mann-Kendall method. The contour maps of the average annual ET0 in Tibet are obtained using the Golden Software Surfer 8.0. The spatial distribution of the average annual ET0 in Tibet is analyzed with the function of spatial analysis. The results indicate that:the daily ET0 curves of Changdou, Linzhi and Naqu are approximately the same, showing a single peak parabolic shape; and the daily ET0 curves of Lhasa, Rikaze and Zedang are also approximately the same. The curves from June to September quickly take on the downward trend; ET0 of the Shiquanhe presents individual change trend. As for all the observation sites, the maximum monthly ET0 is found in June,and the minimum is in December. In Rikaze, ET0 mainly shows the decreasing trend each month and in wet and dry seasons very significantly, followed by Zedang. While ET0 mainly shows the increasing trend in Linzhi. The Mann-Kendall test also indicates that the decreasing in annual ET0 appears to be the dominate trend in most stations of Tibet. The spatial distribution of average annual ET0 reveals that the ET0 values are higher in the eastern and central-southern regions than those in the west and north as well as in the south-eastern fringe in Tibet.
Estimation of regional surface evapotranspiration using MODIS Products
LIU Chao-shun, GAO Wei, GAO Zhi-qiang
2009, 20(6): 782-788.
Abstract:
The idea of the spatial local similarity is introduced to improve the thermal enhance method for fully using the advantages of the temporal and spatial resolutions of MODIS data. Based on the modified Surface Energy Balance Algorithm for Land (SEBAL) model and MODIS products, the retrieval and the verification of the regional surface evapotranspiration(ET0) in Shandong Province show that the simulation results of the remote sensing model are in good agreement with those in situ observation, and the mean daily relative errors are about -11.34%. The monthly changes of ET0 in different land use and land cover (LULC) types in 2005 and 2006 are analyzed. It is found that the monthly average ET0 is highest in water areas, followed by paddy fields. A similar ET0 variation is found over woodlands, dry lands and grasslands. The ET0 minimum is obtained on urban lands.
Runoff-yield model based on statistical theory
LIANG Zhong-min, SHI Ye, LI Bin-quan, YU Zhong-bo
2009, 20(6): 789-793.
Abstract:
Based on statistical theory, a runoff-yield model, considering the spatial variations of rainfall, soil infiltration capacity and water storage capacity, is proposed in this paper. It is supposed that the spatial variations of a rainfall event could be described using a Probability Density Function(PDF) or a Cumulative Distribution Function(CDF), and the specific PDF or CDF at every time step of the rainfall event is estimated by adopting the goodness-of-fit approach to match the curve with the real rainfall data. The parabolic types of mathematical functions are used to represent the spatial distributions of soil infiltration capacity and water storage capacity. According to the joint probability distribution of rainfall and soil infiltration capacity, the distribution of surface runoff is deduced from the infiltration excess mechanism, and the further analytical solution to surface runoff is obtained. Infiltration supplements soil moisture, and when infiltration reaches the field capacity, it yields the groundwater flow which is calculated with the amounts of infiltration and the distribution of the water storage capacity. For instance, the proposed model is applied to Dongwan Basin, a semi-humid region located at the middle reach of Yellow River. Results are also compared with those obtained by the Xinanjiang model. It turns out that the statistically-based runoff-yield model could achieve the promising results with acceptable accuracy for flood events' simulation and forecast.
Verification of the bi-directional stage routing model for a tidal river
BAO Wei-min, ZHANG Xiao-qin, QU Si-min, JIANG Peng, CHEN Bin
2009, 20(6): 794-799.
Abstract:
If it is assumed that the flood and tidal waves in a tidal river are independent of one another, river stages can be considered as the superposition of bi-directional propagation, namely flood waves from the upstream and tide waves from the downstream. Based on the assumption, a bi-directional stage routing model (BSM) for a tidal river is developed according to the basic stage routing equation derived from the storage equation and the water balance equation. In order to prove the feasibility of the separation of flood and tidal waves, three tests are conducted by using the approaches of the ideal models to analyze the assumption, stability, rationality and validity of the BSM. The results show that the structure of the BSM is reasonable, and its performance is satisfactory.
Impacts of tourism on water storage and regulation of meadow soil in Napahai lakeshore wetlands
ZHANG Kun, TIAN Kun, LU Xian-guo, LUO Shan, LI Ji-yu, LI Ning-yun
2009, 20(6): 800-805.
Abstract:
The impact of the tourist disturbances on the water storage and regulation of the meadow soil is analyzed based on the field investigation and the laboratory analysis. The results show that tourist activities destroy the upper layer of the meadow soil badly. With the rise of the disturbance intensity, the soil bulk density increases in the upper 0~20 cm, the soil porosity and water holding capacity declines rapidly, and the saturated water content decreases by 10%, 48% and 75% in the slight, moderate and severe disturbance intensity, respectively. It indicates that the water storage of the meadow soil degrades badly. In the non-disturbance meadow soil, the hydrological spaces, the non-capillary porosity, the initial infiltration rate and steady infiltration rate are 1 897g/kg, 44%, 3.14 mm/min and 1.92mm/min, while in strong disturbance area they decrease by 77%, 43%, 94% and 96%, therefore, the water storage and the regulation of meadow soil degrades badly by the tourist disturbances in Napahai lakeshore.
Distributed hydrological model and eco-hydrological effect of vegetation in Karst watershed
ZHANG Zhi-cai, CHEN Xi, SHI Peng, WEI Ling-na
2009, 20(6): 806-811.
Abstract:
On the basis of the characteristics of the porous and fissure water flow in the karst watershed, a mixed runoff routing method integrating interactions of the Darcy flow, fissure flow and channel storage routing, is developed and used to improve the Distributed Hydrology-Soil-Vegetation Model (DHSVM). The improved model is applied in a small watershed of Chenqi with in the Puding Karst Ecohydrological Observation Station, Guizhou province. The model is calibrated and validated based on the observation data of the stream flow, the vegetation interception, the evapotranspiration and the soil moisture. The results show that this improved DHSVM is able to simulate the observed hydrograph with sharply raised and recessed flow characteristics, as well as evapotranspiration and soil moisture. The improved DHSVM is also able to simulate soil moisture content and evapotranspiration as well as their interactions with precipitation,karst fracture and vegetation cover. This study is very useful for analyzing the eco-hydrological processes and the eco-environmental effects with the changing land cover and land use in the Karst region Southern China.
Experimental study of the effect of hydrodynamic conditions on fish growth
LIU Wen, ZHUGE Yi-si, OUYANG Li, YU Wei, LIU De-fu
2009, 20(6): 812-817.
Abstract:
To find out the appropriate hydrodynamic conditions for fish growth is an important issue in present eco-hydraulic research. The experimental study presented here is to investigate the effect of the hydrodynamic conditions on fish growth. Especially, the Carassius auratus is chosen here for the case study through taking segmentation experiments in the graded ring shape flume. The detailed hydrodynamic characteristics of flumes which are relevant to fish growth are obtained through the 3D numerical simulation of the flume's flow field. Compared with the simulation results and the on-site measurements, the simulation is shown to be reliable. Combining the relative daily growth rate of Carassius auratus with the flow detail characteristics which are quantized by three hydrodynamic characteristic variables including flow velocity, velocity gradient and kinetic energy gradient, the quantitative relationship is established between the fish growth and the hydrodynamic characteristic variables. There is a short-term effect of flow velocity stress on the growth of Carassius auratus, and 0.2m/s is a very feasible velocity for the growth of Carassius auratus. A negative correlation is found between the relative daily growth rate and the kinetic energy gradient with the relative daily growth rate decreasing with the increase of kinetic energy. The threshold of kinetic energy gradient of the growth of Carassius auratus is 0.009J/(kg·m).The quantification of the hydrodynamic conditions of fish growth can provide the quantitative basis for the ecological water conservancy planning.
Artificial resistance of Eulerian-Lagrangian method in 3D numerical model
HU De-chao, ZHAO Wei-yang, ZHONG De-yu, ZHANG Hong-wu
2009, 20(6): 818-823.
Abstract:
The artificial resistance of the Eulerian-Lagrangian Method (ELM) in a 3D hydrodynamic model is observed and characterized by a rising free-surface elevation when the time step decreases. The phenomenon is illustrated and investigated by combining the numerical experiments and the formal analysis. The analysis indicates that the abnormality results from the linear interpolation of the ELM which does not match the nonlinear distribution of the velocity. Based on the analysis, the phenomena are explained. Moreover, the computations by a 3D hydrodynamic model using the sigma-coordinate indicate that the artificial resistance of the ELM is universal, but the grid which follows the topography and free surface better will alleviate its negative influence.
Flow characteristics in a circular-section bend of high head spillway tunnel
SHA Hai-fei, WU Shi-qiang, ZHOU Hui
2009, 20(6): 824-829.
Abstract:
Large-scale physical model experiments (1:38) combined with three-dimensional (3D) Reynolds stress question model(RSM) numerical modeling are used in this study to explore the hydraulic characteristics in a circular-section bend of high-head spillway tunnel. The 3D RSM is used to simulate the incoming velocities under different pre-designed bend radius and angle conditions, as well as the pressure and velocity distributions in the bend. The simulations compare well with the experimental data. Both occurrence and development of the secondary circulation in the bend are successfully simulated by RSM. An expression for optimizing the minimum bend pressure is derived. The expression establishes the relation between the bend pressure and velocity, and the pre-designed bend radius and angle conditions. The result of using the expression shows that the bend radius is the premier parameter to be considered when designing a circular-section bend of high-head spillway tunnel.
A coupled seepage-horizontal well flow model and numerical experiments
DONG Gui-ming, SHU Long-cang, WANG Mao-mei, LU Cheng-peng, LIU Li-hong
2009, 20(6): 830-837.
Abstract:
The coupled mathematical model of seepage and the horizontal well flow is established based on the motion and continuity equations of the horizontal well flow with the lateral inflow and outflow, and used to calculate numerically the mixed head loss of two flows. The effect of the frequent modified method of friction coefficient on the calculation results is analyzed. The results show that there exists little effect on calculation results as for the laminar or smooth turbulent flow, but great effect as for rough turbulent flow. Furthermore, for the laminar or smooth turbulent flow, a new method for determining the demarcation point of flow pattern is proposed to judge the pattern of the horizontal well flow. And the calculation results show that this method is reliable and reasonable.
Analysis of water movement in landfill cover soils using information theory measures
ZHANG Wen-xian, ZHANG Zhan-yu, WANG Kang
2009, 20(6): 838-844.
Abstract:
The water movement in landfill cover soils is studied using the information theory measures. The volumetric soil water contents beneath landfill obtained from the field experiments, and the simulations using the Active Region Model (ARM) and the continuum soil model are used in this study. ARM performs better than the continuum soil model compared to the observations. The time series of simulated soil moisture contents is encoded into a binary form with ‘zero' and ‘one' respectively representing the situations of below and above the mean soil moisture content. The information content is evaluated using the information entropy and the mean information gain. The complexity of flow patterns is quantified using the effective complexity value and the fluctuating complexity value. The result shows that the information theory measure appears to be a versatile tool of discriminating the soil moisture models. The time series of soil moisture contents simulated by ARM retains more information contents and complexities compared to those simulated by the continuum soil model.
Model for estimating technical parameters of sand furrow irrigation
ZHAO Wei-xia, ZHANG Zhen-hua, CAI Huan-jie, SHAN Zhi-jie
2009, 20(6): 845-850.
Abstract:
Based on the analysis of the soil infiltration rule of the Sand Furrow Irrigation (SFI), a model for estimating the technical parameters for SFI is established according to the water-balance principle. These technical parameters are the ditch width and height, the permeable boundary height, and the emitter discharge rate. The experiments about the constant-head well infiltration and the Philip model are used to estimate the soil infiltration capacity. Based on the technical parameters calculated by this model, the experiments about the SFI are carried out to verify the model's feasibility. The factors affecting the model's accuracy are also analyzed. The results indicate that the model has the high precision to design the technical parameters for the SFI.The soil water sorption and soil water transmissivity are the function of the time in the two-dimensional constant-head well infiltration. The changing water depth and wetted perimeter are other factors affecting the model's accuracy.
Scheme of impounding in advance for the Three Gorges Reservoir by considering the comprehensive utilization benefits
LIU Xin-yuan, GUO Sheng-lian, LIU Pan, LI Xiang
2009, 20(6): 851-856.
Abstract:
Considering the flood control, the power generation, navigation and the impounding ratios, a multi-objective scheme of impounding in advance is developed. An optimization-simulation-test algorithm is proposed, and the optimal impounding schemes for the Three Gorges Reservoir (TGR) are derived using the multi-objective genetic algorithms. The results show that under the condition of ensuring flood safety, the optimal schemes can generate 17% extra hydropower energy, save 44% flood water resources and also improve the fullness storage and navigation guarantee ratios greatly. To maximize comprehensive utilization benefits on the premise of the flood control safety, the design flood routing method is well combined with the optimization method by scientifically dividing flood storage capacity into two parts and optimizing the reservoir impounding schemes, which provides a new way for studying the reservoir impounding.
Decision-making on reservoir flood control level and its control manner in post-flooding seasons for Biliuhe Reservoir
ZHOU Hui-cheng, WANG Fu-xing, LIANG Guo-hua
2009, 20(6): 857-862.
Abstract:
Due to the characteristics of flood in regions in North China, it is difficult to determine the flood prevention standard after dividing the whole flood season into sub-seasons. This study develops alternatives for the reservoir's limited water level in post-flood seasons through optimization based on the three angles:the flood prevention, flood utilization and the balance between them. A multilayer fuzzy optimal selection model is established by coordinating the complex relationship among the multi-objectives. The proposed method is applied to Biliuhe reservoir and raises the limited water level in post-flood seasons without decreasing the flood prevention standard. The results show that it can provide technical support for the decision-making and be applied to those reservoirs in the water shortage regions in North China.
Optimization model for reservoir sediment regulation
GAN Fu-wan, LI Yi-tian, DENG Jin-yun, CHEN Jian
2009, 20(6): 863-868.
Abstract:
The optimizing sediment regulation will safeguard long-term reservoir operations and maximize the reservoir effectiveness. In this study, an optimization model for reservoir sediment regulation is developed based on the principle of efficiently removing sediment. The reservoir sedimentation is calculated using a one-dimensional water-sediment transport model, the back-propagation neural network is adopted in the model training processes, and a genetic algorithm is used to ensure the high performance in the model calibration. The model is applied to the Three Gorges Reservoir. The result shows that the model is capable of finding the balanced optimized solution for the reservoir sediment regulation and maximizing the reservoir power generation.
Assessment method for extreme flood disaster losses and its application
QIU Lei, WANG Hui-min, MA Shu-jian
2009, 20(6): 869-875.
Abstract:
Extreme flood is characterized with low frequency but large affecting area and huge economic loss. The natural and social attributions of extreme flood disaster were analyzed in the paper. The current assessment methods are mainly used for common frequently-occurred flood, but not suitable for extreme flood.The spatial information grid of hydrological characteristics and social economic attribution for extreme flood were constructed through referencing the spatial information technology. In further, the spatial information grid model of extreme flood losses was established with the spatial topological relationship of different grid information. The model can not only reflect the spatial characteristics of extreme flood, but also assess the losses of extreme flood through combining relevant database. The model was employed to assess the direct economic loss in main city district north to Songhuajiang River in Harbin City, which indicates the model is feasible in practice for extreme flood disaster losses assessment.
A review of research and application of AGNPS model
SUN Jin-hua, ZHU Qian-de, YAN Zhi-jun, LU Hai-ming, WANG Hui-rong
2009, 20(6): 876-884.
Abstract:
The Agricultural Non-Point Source(AGNPS) pollution is widespread, random, and difficult to monitor and treat. It has been the focusing issue that models can be used to describe the transportation process, to calculate the pollutant load and to assess mitigation measures for AGNPS pollution in the field of the water environmental protection and treatment. This paper reviewed the research and application of the AGNPS model both at home and abroad, and describes the structure and mechanism. The results show that AGNPS model is acceptable. The simulation results in the hydrological years are better than those in the rainfall-runoff events. The simulation accuracies in runoff, sediment erosion, nitrogen and phosphorus load are different in the different research zones. It is realistic to assess the effect of the management measures and judge the critical zone. The grid-cell division, the sensitivity analysis and the parameters adjustment affect the model's accuracy to a larger extent. In view of the feature and the research status of AGNPS, the expectation and modification is put forward.
Advance in inverse problems of environmental hydraulics
LIU Xiao-dong, YAO Qi, XUE Hong-qin, CHU Ke-jian, HU Jin
2009, 20(6): 885-893.
Abstract:
The inverse problems exist widely in the field of the environmental hydraulics. The flow and pollutants transportation, coupled with flow, can be identified and controlled by the study of the environmental hydraulics, which benefits the continual utilization of water resources. Based on the idea of the inverse problem, the connotation of the inverse problems of the environmental hydraulics is expounded. The inverse problems of the environmental hydraulics are sorted according to the various points of view. And its importance in research is emphasized. In this paper, the present study methods and results are analyzed from the aspects of the inverse problems on the parameter, source, boundary condition, initial condition and shape in the environmental hydraulics. Some unresolved issues and future research perspectives are also addressed.
Theoretical analysis frame based on general entropy and intelligence integration methodology for flood disaster risk management
JIN Ju-liang, WANG Yin-tang, WEI Yi-ming, WANG Zong-zhi, LIU Ke-lin
2009, 20(6): 894-900.
Abstract:
Based on the background analysis of flood disaster risk management research, the theories of general distribution function and its entropy can be used to effectively describe and analyze the uncertainty information of flood disaster risk management system. Based on the mechanism of producing flood disaster risk and the integration methodology of risk management theory, water conservancy science, information science and intelligence science theories, the theoretical frame and its main contents of the comprehensive analysis theory based on general entropy and intelligence integration methodology for flood disaster risk management are presented, which consists of flood hazard analysis based on the general entropy and intelligence integration methodology, flood disaster vulnerability analysis based on the general entropy and intelligence integration methodology, flood disaster loss analysis and evaluation based on general entropy and intelligence integration methodology, and flood disaster risk decision-making analysis based on the general entropy and the intelligence integration methodology. The frame can also be applied to risk management of other disasters.