• 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

2015 Vol. 26, No. 5

Display Method:
Analysis of the dominant causes for runoff reduction in five major basins over China during 1960—2010
ZHANG Shulei, YANG Dawen, YANG Hanbo, LEI Huimin
2015, 26(5): 605-613. doi: 10.14042/j.cnki.32.1309.2015.05.001
Abstract:
A sharp reduction of annual runoff has been observed during the past 50 years in five major river basins of China, namely Songhuajiang River, Liaohe River, Haihe River, Yellow River and Hanjiang River. In this study, changes of catchment runoff and their causes were investigated in 107 small catchments with relatively small artificial water uses from the 5 basins. The coupled energy-water balance equation based on the Budyko hypothesis is employed to estimate climate elasticity and landscape elasticity of runoff, which were then used for attribution analysis of runoff decrease in these 107 catchments. The results show that the catchment annual runoff is relatively less sensitive to climate and landscape changes in relatively humid regions while it is more sensitive to climate and landscape changes in relatively arid regions. By the attribution analysis, it is found that the change in potential evapotranspiration has little impact on runoff in most of the 107 catchments while the dominant factors leading to runoff reduction are the changes in precipitation and catchment landscape. It is also seen that the landscape change induced catchment runoff reductions have significantly intensified in the recent 10 years. Based on the analysis of NDVI (Normalized Difference Vegetation Index) during the recent 30 years, vegetation increase appears to be the dominant change in landscape. This implies that the soil and water conservation project carried out in China has achieved a notable ecological effect although it is also one of the major causes of runoff reduction.
Estimation of potential evapotranspiration and its variability in the upper and middle reaches of the Heihe River basin
ZHAO Jie, XU Zongxue, ZUO Depeng
2015, 26(5): 614-623. doi: 10.14042/j.cnki.32.1309.2015.05.002
Abstract:
On the basis of the MODIS LAI remote sensing products, China Meteorological Forcing Dataset and other multi-source datasets, the Shuttleworth-Wallace (S-W) model, which considers the temporal variation of leaf area index (LAI), was applied to estimate potential evapotranspiration (ETP) during the period of 2000—2010 in the upstream and midstream areas of the Heihe River basin. To investigate the temporal and spatial variability of ETP, sensitivity of ETP to meteorological parameters and LAI was calculated for each land cover type. To compare ETP and ET0 values for runoff simulation, a conceptual hydrologic model with precipitation and ETP or ET0 was developed in the upstream area of the Heihe River basin. Results showed that: ① S-W model, based on high-resolution remote sensing datasets, was able to accurately estimate annual and seasonal ETP in large river basins with complex underlying surfaces as well as in ungauged basins. The values of ETP in summer contributed more to the annual value than those of other seasons. ETP in areas with different land cover types varied greatly. Generally speaking, ETP decreased with the development of vegetation. ② In the study area, ETP was most sensitive to relative humidity. The sensitivity of ETP to LAI was as great as that to net solar radiation. The sensitivity of ETP to meteorological parameters and LAI became greater with the decline of vegetation. ③ Compared with hydrologic model with ET0 calculated by P-M model, the model with ETP better simulated the depth of runoff at Yingluoxia hydrologic station. Hence, ETP calculated by S-W model was more suitable for the simulation of runoff in the present study.
Effects of DEM source and resolution on the HEC-HMS hydrological simulation
GAO Yufang, CHEN Yaodeng, JIANG Yifang, PENG Tao
2015, 26(5): 624-630. doi: 10.14042/j.cnki.32.1309.2015.05.003
Abstract:
Hydrological simulations are affected by the parameters derived from DEM, which describes the water- shed features. Xitiaoxi River basin was selected to simulate two runoff processes in Jun and Aug to Sep 2011 using the HEC-HMS model with ASTER 30 m DEM、 SRTM 90 m DEM and DEM resample data as input for HEC-geoHMS to derive the basin characteristics. The results showed that, the simulated and observed flood were fitting well and the efficiency coefficients of the model were all larger than 0.82, Uni-modal flood showed a better performance in runoff simulation than multi-modal flood. The efficiency coefficients of model based on SRTM 90 m was larger than based on ASTER 30 m DEM and resampled 90 m DEM. The efficiency coefficients of model based on resampled DEM had nonlinear relationship with DEM resolution. The relative error of HEC-HMS simulations based on ASTER 30 m DEM and SRTM 90 m DEM had a difference of 3%—5%. The relative error of simulations based on the SRTM 90 m DEM and the resampled 90 m DEM had a difference of 2%—4%.The maximum difference between the relative error of HEC-HMS simulations based on the resampled 90 m DEM was 11%.
Analyzing the influence of geomorphologic structure factors on runoff characteristics of catchments
LIU Jintao, WANG Aihua, WEI Yu, CHENG Bingfeng, HAN Xiaole
2015, 26(5): 631-638. doi: 10.14042/j.cnki.32.1309.2015.05.004
Abstract:
Geomorphologic structure factors significantly affect hydrological processes. In this study, eleven catchments which located in the main storm center in the Huaihe River basin were adopted as study areas. We analyzed the influence of geomorphologic structural factors (the characteristic values of hypsometric curve, et al.) on the hydrological characteristics. The hydrological characteristics include annual mean runoff coefficient and the slope of the flow duration curve in its upper and lower portions(Sfh and Sfl). The results show that the characters of hypsometric curve (integral value, slope) have greater influence on runoff characteristics than other factors. For example, the coefficient of determination between annual mean runoff coefficient, Sfh and the slope of hypsometric curve is 0.77 and 0.67, respectively, and the coefficient of determination between Sfl and the integral of hypsometric curve is 0.65. They indicate that, the larger the slope of hypsometric curve, the steeper terrain of a catchment, in which it is prone to flash flood and the annual mean runoff coefficient would be larger. On the contrary, the smaller the integral value of hypsometric curve, the flater terrain of a catchment, in which its flood hydrograph tends to become smoother and it has a higher storage capacity.
Characteristics of fractionation of hydrogen and oxygen isotopes in evaporating water in the typical region of the North China Plain
MA Bin, LIANG Xing, JIN Menggui, LI Jing, NIU Hong
2015, 26(5): 639-648. doi: 10.14042/j.cnki.32.1309.2015.05.005
Abstract:
To study the characteristics of fractionation of hydrogen and oxygen isotopes in evaporating water in Hengshui, a typical region of the North China Plain, two sets of outdoor water evaporation experiments with different salinities were conducted under local meteorological conditions. Water was collected from deep fresh water (TDS=0.61 g/L) and shallow saline water (TDS=7.97g/L), respectively. The experimental results showed an exponential relationship between δD and δ18O in residual water and f (the volume ratio between the residual water and the initial water), which was in agreement with Rayleigh fractionation model results. The slopes between δD and δ18O in the residual surface water were 4.78 and 4.69 for the fresh water and saline water, respectively. It was also shown that the average degrees of enrichment of the hydrogen isotope D were 4.82 and 4.76 times those of the oxygen isotope18O in the fresh water and saline water, respectively. The ratios between the δD and δ18O variations of the residual surface water and the evaporation were 2.68‰/cm and 0.56‰/cm, respectively, for the fresh water; and were 2.78‰/cm and 0.61‰/cm for the saline water during the experiment period. Nevertheless, the ratios at different evaporating times had no significant correlations with each other. Isotopic statification was rarely observed in different water layers due to the diffusion effect of water molecules. Moreover, the salt effect on the stable isotopic fractionation during the pan evaporation experiment under the typical climatic conditions was negligible, probably due to the low salt concentration in the saline water.
State-space prediction of soil water content on a hillslope in the gully region of the Loess Plateau, China
DUAN Liangxia, HUANG Mingbin, ZHANG Luodan, SUO Lizhu, ZHANG Yongkun
2015, 26(5): 649-659. doi: 10.14042/j.cnki.32.1309.2015.05.006
Abstract:
Soil water content is one of the key factors affecting plant growth and eco-environment reconstruction on the Loess Plateau of China. To assess the spatial heterogeneity of soil water content and its potential influencing factors on a hillslope in the gully region of the Loess Plateau, the state-space approach and a classical linear regression approach were applied in order to identify and quantify the significant relationships between soil water content and elevation, contents of clay, silt, and sand, median soil grain size, and fractal dimension. The results showed that the soil water contents in different soil layers exhibited moderate variation, and were significantly influenced by the elevation, the contents of clay, silt, and sand, and by the fractal dimension. Autocorrelation for the six potential influencing factors were conducted, and cross-correlation functions indicated strong spatial dependences between the soil water content and the elevation, the contents of clay, silt, and sand, and the fractal dimension. The state-space approach simulated the soil water content much better than any equivalent linear regression method. The best state-space model included the elevation, the sand content, and the fractal dimension, which could explain 99% of the variation in the soil water contents; the model accurately predicted the soil water contents along two transects. Consequently, the state-space analysis was verified to be an effective tool for estimating soil water contents in different soil layers on a hillslope on the Loess Plateau.
Movement characteristics and transport laws of the bimodal bed load
SUN Dongpo, LIU Mingxiao, WANG Pengtao, LI Guodong, ZHAO Yafei, DONG Mingjia
2015, 26(5): 660-667. doi: 10.14042/j.cnki.32.1309.2015.05.007
Abstract:
The non-uniform bed load transport is a complicated coherent physical process of the fluid and solid in river. The research into the motion characteristics, transport laws as well as the action mechanism of influencing factors can help to not only complement the fundamental theories in river dynamics, and but also solve the urgent requirements from the practical engineering sediment. A series of flume experiments was carried out using the techniques of image recognition and instant monitoring for bed load. By introducing the comprehensive flow intensity Ψb which reflects the thickness ratio of the bed η, properties of the viscous sublayer, the characteristic Froude number Frb, the transport characteristics of the non-uniform bed load with a bimodal distribution were investigated under several conditions such as different flow intensities and various compositions of bed material, with the effect of particle non-uniformity on transport rate of bed load being especially considered. By means of key factor identification and dimensional analysis, the transport mode of the non-uniform bimodal bed load was proposed. A formula for calculating the transport intensity of bed load was developed, which is expressed as a dimensionless function of the transport intensity Φ' and comprehensive flow intensity Ψb based on characteristic factors near the bed. An analysis of the transport mechanism of the bimodal bed load indicates that the ratio of coarse to fine particles in the composition properties of the non-uniform sediment is an important parameter affecting the value Φ'. It is found that the collapsing effect of fine particles on coarse particles has an important influence on the movement of coarse particles, and therefore, the transport rates of bimodal bed load present a hump curve with the variation in the degrees of particle non-uniformity, wit the corresponding ηc of about 3∶7 for the peak rate.
Experimental study on overflow breaching of embankments constructed with silty clay
WEI Hongyan, YU Minghui, LI Yitian, WU Songbai
2015, 26(5): 668-675. doi: 10.14042/j.cnki.32.1309.2015.05.008
Abstract:
The purpose of this study is aims to investigate overflow breaching process of embankments constructed with silty clay and their as well as its response to flow and soil characteristics. Nine groups of experiments were conducted on the overflow breaching of cohesive embankments were conducted in a bend flume. Factors considered included inflow discharge, water content, and porosity of the embankment materials. Results showed: It has been found that the breach process can be categorized into a vertical erosion stage and lateral widening stage, with headcut retreat as the main form of erosion form during the vertical erosion stage. The soil water content and porosity not only affected the breach development rate, but also determined the final breach type. The inflow discharge, however, only affected has impact on the breach widening rate. The flow velocities and water level close to the breach were both restricted by the breach height. The relationship between the soil water content, soil porosity, and soil cohesion force was fitted using by the experiment data. A formula expressed by the soil cohesion force and flow parameters for computing the headcut retreat rate was proposed and was proved to be reasonable.
Sedimentation characteristics in the Three Gorges Reservoir during the initial operation stage
LI Wenjie, YANG Shengfa, FU Xuhui, XIAO Yi
2015, 26(5): 676-685. doi: 10.14042/j.cnki.32.1309.2015.05.009
Abstract:
The sedimentation characteristics in the Three Gorges Reservoir (TGR) are studied by analyzing measured sediment load and cross section data. Results indicate that the total deposition amount and effective sediment export ratio from 2003 to 2013 are 1.531 billion tons and 24.5%, respectively, and both are less than those estimated during design. The sediment is primarily deposited in the wide and curved reaches in the permanent backwater region. It distributes evenly over the cross sections in the wide reaches and on the side of the sections with low velocity in the curved reaches. No deposition occurs in gorges. The deposition rates near the dam tend to decrease, while those of the upper reaches are increasing. The longitudinal particle size variation is not obvious, and the median particle diameters of the deposition in the permanent backwater region are mostly less than 0.01 mm. The thalweg of the gorge reaches have no changes, and the deposition delta is not found. The deposition in the backwater zone and the associated increasing of the tail water level are less than previous estimations. These suggest that the gorge reaches play a role of a local erosion base level due to their sufficient sediment carrying capacities, and it is unlikely that a unified equilibrium bed slope will be developed in the TGR.
Modelling of hyperconcentrated floods in the lower Yellow River using a coupled approach
XIA Junqiang, ZHANG Xiaolei, DENG Shanshan, LI Jie
2015, 26(5): 686-697. doi: 10.14042/j.cnki.32.1309.2015.05.010
Abstract:
Hyperconcentrated sediment-laden floods usually occur in the Lower Yellow River (LYR) during rainy seasons. During these floods, extreme high water levels and strong channel scour in local reaches often occur, which may cause the damage to the safety of flood control engineering. Therefore, it is necessary to adopt one-dimensional (1-D) morphodynamic models to simulate hyperconcentrated floods and corresponding channel evolution in the LYR. In the current study, a 1-D coupled morphodynamic model has been developed to simulate hyperconcentrated floods. In this model, the standard Saint-Venant equations are modified, and the sediment concentration and bed evolution terms are directly included in the modified equations. These equations are used together with the non-equilibrium transport equation for graded sediments and the equation of bed evolution. Since the governing equations are solved jointly, the hydrodynamic, sediment transport and morphological parameters are obtained simultaneously. The model was first applied to simulate a hyperconcentrated flood event occurring in 1977 in the LYR, with the field measured data of discharge, total and graded sediment concentrations at hydrometric sections being used to calibrate the model. It was then used to predict the discharge and sediment concentration hydrographs in the 2004 flood event, again using the field measured data to verify the model. Close agreement was obtained between the model predictions based on the coupled solution and the observed data.
Imaging-based measurement of pickup probability for sediment entrainment
MIAO Wei, CHEN Qigang, LI Danxun, ZHONG Qiang
2015, 26(5): 698-706. doi: 10.14042/j.cnki.32.1309.2015.05.011
Abstract:
We present a novel, high-speed imaging method for measuring the pickup probability for sediment entrainment under flowing water. The pickup probability is defined as the proportion of sediment particles entrained from a given bed region during a turbulent bursting period, so the measurement necessitates a least sampling frequency corresponding to the intermediate range of sediment motion. Moving particles are identified by examining the gray difference between two successive images, and the probability for sediment motion is determined by counting the number of particles in motion. The pickup probability equals the probability for sediment motion times the interval between two consecutive images divided by the intermediate temporal range. The method has been successfully applied to the measurement of bed-load transport in closed channel flows. Preliminary results show that the measured pickup probability for sediment entrainment at critical conditions remains at 2.27%, similar to previous results in the literature.
Studying on dividing and connecting of the hydrology standard between river and sea navigation engineering
ZHANG Xingnong, CHEN Changying, LIU Hui
2015, 26(5): 707-713. doi: 10.14042/j.cnki.32.1309.2015.05.012
Abstract:
Aiming at problems existing in hydrology standard for navigation engineering of tidal reach, especially difference and junction of confirmation of the design water level and research of flow and sediment for seaport and inland navigation engineering, studying on demarcation and connection of hydrology standard of tidal reach was performed. Through expounding the basic features of the tidal reach, hydrology factors of all kinds of navigation engineering were analyzed. Then, the ratio of two characteristic values that are annual average of in-year variation amplitude of monthly average water level and annual average of tidal range, was presented as a dividing index of different sections in the tidal reach. By means of case study and calculation, demarcation and connection of the hydrology standard of two kinds of engineering was demonstrated. The result shows that the ratio reflects the influence of runoff and tide to hydrology condition in different sections. The hydrology standard of two kinds of engineering in tidal reach can be divided and connected preferably according to its different value.
Hydrodynamic dispersion and hyporheic exchange in a small urban stream
YU Jing, ZHANG Hua
2015, 26(5): 714-721. doi: 10.14042/j.cnki.32.1309.2015.05.013
Abstract:
To reveal the physical transport processes in a small urban stream and analyze exchange processes between water column and transient storage zone under base flow, field experiment using LiBr as conservative tracer and numerical simulation using One-dimensional Transport with Inflow and Storage model (OTIS) were carried out to quantitatively characterize hyporheic exchange. The longitudinal dispersion coefficient (D) reach-scale transient storage area (AS), main channel cross section area (A), and the hyporheic exchange coefficient (α) were estimated along a 1 300 m stream reach. Transient storage metrics DaI and ERMS values showed an excellent fit of the model. The results of four stations (A, B, C and D) downstream the location of tracer injection demonstrated that hydrological parameters D, AS, A, α varied with hydrological conditions. The hyporheic exchange of upper reaches (0—600 m) was weak and convection and dispersion were dominant processes. The middle reaches of the river (600—1 300 m) had stronger transient storage and longer hydraulic retention time. The exchange coefficient of segment BC (600—1 000 m) and CD (1 000—1 300 m) were (3.42×10-6±0.65×10-6) s-1 and (2.87×10-6±0.81×10-6) s-1, respectively. A lateral flow of 2.2×10-5 m3/(s·m) contributed to BC. In general, stream channelization and lack of sediment on the streambed reduced the capacity of hyporheic exchange in urban streams.
Study on the migration of dense non-aqueous phase liquids in heterogeneous fractured media
DENG Yaping, ZHANG Ye, SHI Xiaoqing, WU Jichun
2015, 26(5): 722-730. doi: 10.14042/j.cnki.32.1309.2015.05.014
Abstract:
Due to the strong heterogeneity of fractured media, the migration behavior of Dense Non-Aqueous Phase Liquids (hereafter referred to as DNAPLs) in fractured media is more complicated than in pore media. Binary variables of fractured media are initially simulated using the indicator simulation and finally modified with simulated annealing algorithm to generate the stochastic permeability fields (SPF). By simulating the migration of DNAPLs in fractured media with the T2VOC, we can study the effects of correlation length, anisotropy ratio, inclination of asperity contacts and degree of heterogeneity on the migration and distribution of DNAPLs. Numerical analysis results suggest that a worse correlation among adjacent asperity contacts leads to a larger pollution scope of DNAPLs; a larger anisotropy ratio and inclination lead to more residual DNAPLs; with increasing correlation length and anisotropy ratio as well as decreasing inclination, the front surface migration rate of DNAPLs increases; and the increasing heterogeneity of permeability causes an increasing saturation of DNAPLs accumulated in local asperity contacts, and a decreasing migration rate.
Research on data-assimilation combined with roughness correction for dynamic river system
CHEN Yifan, CHENG Haiyang, WAN Xiaoli, FANG Huajian
2015, 26(5): 731-738. doi: 10.14042/j.cnki.32.1309.2015.05.015
Abstract:
In order to synchronously correct river roughness parameters and hydraulic state variables (including discharge, stage or water depth) of river network hydrodynamic model, extended Kalman filter method is used to develop a data assimilation model. This model takes roughness parameters and hydraulic state variables as model state variables for synchronization correction. In a simulation example, it systematically examined and analyzed the factors including roughness dynamic noise level, water level dynamic noise level, initial value of roughness and station number, which have important influence on model correction capability. The results reveal that the present model is able to carry out data assimilation of dynamic river system efficaciously. Corrected roughness values near stations tend to be true values, and those far away from stations tend to be initial values. By adjusting roughness dynamic noise level, it can effectively control roughness correction degree, avoiding calculating failure.
Advances in applied ecological models for estuarine management
SHEN Xia, B. Larry LI
2015, 26(5): 739-751. doi: 10.14042/j.cnki.32.1309.2015.05.016
Abstract:
Estuaries are transitional water zones as functional ecotones connecting rivers and oceans. Both of natural forces and human activities drive estuarine ecosystems variations. Ecological modeling plays a significant role in studying structure and function of ecosystem, simulating processes of ecosystem succession, and understanding response and feedback of biological processes on ecosystem. Hear we review different type of ecological models, and presents their features, strengths and weaknesses, as well as how apply these models to real world problems. Some critical technical questions are discussed, such as variables and functional types of model, model coupling and spatio-temporal scale, as well as parameter determination and uncertainty analysis. In particular, some instances are illustrated to demonstrate how to apply numerical models to serve estuarine integrated management schemes, including ecological engineering design, ecosystem restoration, ecosystem assessment, and system decision support. Although the ecological modeling research in China has made some processes including their applications, there is still a gap in some respects needed to be improved.
Understanding on research hotspot of hydraulic structure engineering professional in National Natural Science Foundation
LI Yanlong
2015, 26(5): 752-758. doi: 10.14042/j.cnki.32.1309.2015.05.017
Abstract:
Water conservancy science and ocean engineering discipline in China have achieved considerable development under the support of the National Natural Science Foundation. This article aims to further clarify the subject development and guide the study orientation of water scholars. Thus, this article analyses the recent research progress of structural engineering disciplines with water science research based on the '2014 hydraulic structures and hydraulic equipment strategy research and academic exchange for young scholars' under the auspices of the National Natural Science Fund Committee, as well as on the application materials related to water subjects and expert comments. We firstly determine the 'reservoir dam engineering full life-cycle performance evolution mechanism' of the major research projects in the hydraulic structure discipline during the 13th Five-Year Plan. Then, we consider eco-hydraulic engineering and water conservancy informatisation, digitalisation, and intelligentisation as priority supports for the interdisciplinary research field. Finally, we propose that the subject is one of the critical scientific issues of the discipline that most demand urgent attention. This paper studies was beneficial to condense key scientific issues and promote the development of water conservancy scientific research for scientific researchers.