• 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

2011 Vol. 22, No. 5

Display Method:
Regional “four-water” transformation based on distributed hydrological model
ZHANG Jun-e, LU Chui-yu, QIN Da-yong, LIU Miao
2011, 22(5): 595-604.
Abstract:
Analysis of "four-water" transformation lays the foundation of the study of water resources problems such as water resources assessment and water cycle changes. In this study, a modified version of the MODCYCLE distributed hydrological model is established in accordance with the local specifications of Tianjin, and then used to analyze the regularity of "four-water" transformation in Tianjin. The original MODCYCLE model was developed by the Department of Water Resources in China Institute of Water Resources and Hydropower Research, and is able to account for the influence of intense human activity, especially when dealing with complex agricultural systems. The analysis result shows that the process of "four-water" transformation in Tianjin is largely influenced by the artificial collateral water cycle, which can be characterized as the reduction in surface runoff, the increase in soil water content, the overexploitation of groundwater, as well as the efficient use of inflow water and transferred water. The quantity of surface water in Tianjin could hardly meet the local demand for water. Although, the current shortfall in water provision is resolved by using upstream inflow and transferred water from other regions, and the issue of future water shortages could be ensured by the South-to-North Water Diversion Project. However, a strict water resources management system should be implemented to gradually reduce the groundwater consumption and to increase the freshwater discharge into the sea.
Prediction of extreme floods in Huaihe River basin under climate change
HAO Zhen-chun, JU Qin, WANG Lu, WANG Hui-min, JIANG Wei-juan
2011, 22(5): 605-614.
Abstract:
Predictions of extreme floods from 2010-2099 are made for the Huaihe River Basin using the projected future temperature and precipitation from 22 global climate models under A1B, A2 and B1 emission scenarios in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4) and the Xin'anjiang monthly distributed hydrological model. The model is calibrated and validated with the satisfied results. The ensemble method is applied in the model prediction. The result shows that the A2 scenario would most likely result in a highest number of extreme flood events, and then followed by the A1B scenario and the B1 scenario, respectively. Under A1B, there would be an increased possibility of extreme flooding in the latter half of the 21st century; while for the A2 scenario, the extreme floods could be concentrated on the period 2035-2065 as well as after 2085. Under B1, the frequent extreme floods would most likely occur around 2070s. By integrating the diverse definitions of extreme events, we classify the extreme events into three groups based on the flood magnitudes. In the first magnitude group, the extreme flood events predicted under the A2 scenario would be the most with the largest average flood volume; while those under B1 would be the least with the minimum value of flood magnitude in the third group. There could be an increased occurrence of the extreme flood events in the first magnitude group among all three scenarios. The highest increase might be found under the A2 scenario and followed by A1B and B1. The proportion of extreme flood events in each of the three magnitude groups would also vary under different scenarios. The extreme flood events of the second magnitude group could be more frequently encountered under A1B and A2; while B1 could result in more third group extreme flooding. Nevertheless, there would only a small proportion of extreme flood events with the flood magnitude exceeding the great flood of 1954 in the first magnitude group.
Influence of spatial resolution in a regional climate model on summer precipitation simulation
LIU Xiang-pei, WANG Han-jie, LIU Jin-bo
2011, 22(5): 615-623.
Abstract:
This paper utilizes the latest version of Regional Climate Model (RegCM4) with three different horizontal and vertical resolutions to simulate the regional climate in China during June to August, 2001-2003. The simulated precipitation is compared to the GPCP (Global Precipitation Climatology Project) precipitation at daily, monthly and seasonal time scales in an effort to study the influence of spatial resolution on summer precipitation simulation. The main conclusions to come out of this study are the following. The new version of RegCM4 is able to better simulate the distribution pattern of precipitation. Simulated precipitation amounts tend to decrease from southeast to northwest, and the amount decreases with the increase of both horizontal and vertical resolutions. Precipitation simulated with horizontal grid spacing of 30 km and 14 vertical levels will have the least bias among the all experiments. The sensitivity of simulated precipitation to the model resolution varies differently over different regions and at different times of the year. The spatial resolution will have more influence on precipitation simulation in higher altitudes. The simulated peak value of daily precipitation decreases with the increase of spatial resolutions. The resolution will have more profound impacts on the low-frequency bias and the 24-day period component in the daily precipitation series. Thus, the system error can be reduced effectively by adjusting the model spatial resolutions.
Hydrological processes in different landscapes on Mafengou River basin
YANG Yong-gang, XIAO Hong-lang, ZHAO Liang-ju, ZOU Song-bing, YIN Zhen-liang
2011, 22(5): 624-630.
Abstract:
There is less research about integrated hydrological processes in alpine cold regions at present. This paper aims to explore the hydrological processes in different landscapes on the Mafengou River basin of an alpine cold region. This is done through the identification of the composition of alpine runoff of different origins including glacier, snow, frozen soil, surface water, groundwater, and precipitation using isotope and hydrochemical methods. A mixing model is employed for hydrograph separation. The result shows that the groundwater from the alpine cold desert zone and shrub zone contributes about 52% of river discharge in the Mafengou River during the wet seasons. The recharge of groundwater is achieved by transforming thawed frozen soil water into river channels, and infiltrating glacier snow melt water and precipitation on the land surface. Other contributions include 11% melt water directly coming from the glacier snow zone, 20% surface runoff on the alpine cold desert zone and alpine shrub meadow zone, 9% thawed frozen soil water from the alpine grassland zone, and 8% precipitation water. The study suggests that the direct runoff generated from precipitation events rarely occurs over the whole basin. Much precipitation will infiltrate into the soil either becoming interflow or recharging groundwater, and then drain into river channels.
River sinuosity in tidal plain and its response to rapid urbanization
ZHAO Jun, SHAN Fu-zheng, YANG Kai, WU E-nuo
2011, 22(5): 631-637.
Abstract:
River sinuosity is an important indicator of channel planform. The city of Shanghai is a typical tidal plain and chosen as the study area in this paper. Sinuosity values in the 1950 were studied for the city centre region with dense river networks. The impacts of rapid urbanization on river sinuosity are diagnosed for the period after 1960. The result shows that the density of river networks in the city centre region has been reduced by 67.22% due to intense human activities since 1950, which resulted in Horton laws of drainage composition no longer holds. The tidal plain is seen as a representation of developing regions on straight rivers. The latter can account for 85.4% of the total number of rivers in the city centre region in the 1950. A further analysis of sinuosity reveals that those straight rivers with sinuosity values less than 1.1 can be as high as 70.57% at the time. The number of destroyed straight rivers in the city centre region was 12 times more than those with higher sinuosity in the past 60 years. We thus propose the adaptation of the index of weighted average river sinuosity for the study of the influence of river network shrinking on river sinuosity. Finally, it is found that in the practice of the comprehensive treatment of Shanghai river system, the tendency is to use engineering-oriented measures rather than replying to natural meandering channels as the curving cut-off measure has been applied to 60.9% river projects.
Statistical analysis of the geometrical form of natural rivers meanders
LI Zhi-wei, QIN Xiao-hua, FANG Chun-ming
2011, 22(5): 638-644.
Abstract:
The river meander is an important geomorphologic component of meandering rivers. Study of the evolution of geometrical form and channel migration of river meanders possesses high academic values. Using an integrated platform of Google Earth satellite images and AutoCAD software, a total of 136 mountain meanders and 325 alluvial meanders in eight rivers from different areas are chosen as statistical samples to define and measure geomorphologic parameters of the samples. The statistical result shows that the meander radius of curvatures in mountainous rivers is in the interval [1.7, 14.8], and the value of the curvature radius for alluvial rivers is [1.6, 38.5]. Statistically, the mean value and standard deviation of the curvature radius in alluvial rivers are much greater than those in mountainous rivers. There is not obvious skew angle tendency at bend apex in mountainous rivers, showing almost equal opportunity for both upstream and downstream development of bend apex. The number of meanders with 85 degree skew angle and greater in alluvial rivers can account for 65.5% of the total river meanders, indicating a tendency for bend apexes to grow in the upstream direction. There is a good liner relationship between the average width and the width of bend apex in alluvial rivers. A certain extent of positive correlation is found between the average river width and the meander neck width. The relationship between the relative transverse skewness and the curvature appears is also linear. These characters manifest the consistency of the shape of a planer cure in river meanders.
Mechanism of outer delta evolution of the Laolonggou tidal inlet in Caofeidian sea area on China’s Bohai Bay
JI Rong-yao, LU Yong-jun, ZUO Li-qin
2011, 22(5): 645-652.
Abstract:
A lagoon-type tidal inlet system with a larger outer delta, namely Laolonggou, is located in the Caofeidian sea area of China's Bohai Bay. With the decrease of the sediment supply in last decades, the seabed was eroded obviously on the sea-side area of the Dongkengtuo barrier island, and the isobathic lines retreated toward the coast. The deep channel of the West branch was also in an erosion state, and the change of erosion-deposition in the outer delta was mainly affected by the Dongkengtuo island. The obvious erosion in the eastern channel is mainly caused by the extension of the Dongkengtuo head land, leading to the increase of the current velocity. The western channel narrows and moves toward the west, due to the extruding of the eastern channel. In recent years, the eastern channel development has been slowing done together with decreasing in the western channel swing amplitude, which is also due to insufficient sediment supply.
Analysis of riverbed form adjustment based on energy dissipation in the Inner Mongolia Reach of Yellow River
SUN Dong-po, YANG Zhen-zhen, ZHANG Li, LI Bin
2011, 22(5): 653-661.
Abstract:
In order to study the adjustment regulation of riverbed form, in view of river energy dissipation, the 50-year river data collected from the Inner Mongolia Reach of Yellow River is analyzed by introducing the targets such as river work, longitudinal and transverse energy slope. It is found that the operation of upstream reservoirs has a great impact on the hydraulic regime of the river reach, such as decreasing the frequency of overbank flooding, increasing the channel width/depth ratio, and enhancing the horizontal activity in the river reach. In the process of riverbed form adjustment under the influence of reservoir operation, there is a close relation between the incoming sediment coefficient and the fluvial facies coefficient, and also between the average swing speed and the characteristic value of water and sediment. The study on the section configuration change, horizontal swing and the energy dissipation reveals that the river flow can directly impact the evolution of channel cross-section. The correlation among characteristics of runoff and riverbed morphology is constrained by the distribution of river energy dissipation. In this studying reach, it is found that the total water energy can roughly balance the required energy dissipation during the various periods of the year.
Bivariate fractal interpolation for estimating rough channel bedform
ZHONG Liang, XU Guang-xiang
2011, 22(5): 662-667.
Abstract:
The rough bedform is estimated using the self-similar characteristics of bedforms together with the bivariate fractal interpolation method that is based upon the iterative function system. The interpolation fields Ak are determined using the Kriging interpolation method with a spherical variogram for Kriging. The vertical scaling factors sm,n are obtained through the use of the multi-variate statistical analysis of interpolated data. The results show that the similarity between the estimated bedforms and the initial bedforms can be improved with increasing the number of data items interpolation ic. In particular, when ic approaches to a very low value of the threshold (0.0625), a high level similarity in bedforms is reached. The estimated fractal dimension will be also close to its theoretical value. The bivariate fractal interpolation method can be used as an effective means of estimating irregular bedforms in rough channels with a high level similarity, where observed data are insufficient.
3D numerical simulation of round horizontal thermal jets in flow
ZHANG Jian, YANG Li, ZHANG Shi-cheng, LÜ Shi-gui
2011, 22(5): 668-673.
Abstract:
According to the computational fluid dynamics theory and the finite volume method, the governing equations of flow and heat transfer are solved for round horizontal thermal jets in flow. Using the Realizable k-ε turbulence model and the semi-implicit method for pressure linked equations-consistent algorithm and considering the buoyancy effect, a 3D numerical simulation of round horizontal thermal jets is achieved in this study. Both flow characteristics and temperature distributions in thermal jets are studied through the numerical experiments conducted under different conductions of velocity ratios and outlet temperatures, and the impact of these conductions on temperature distributions is analyzed. As a result, both velocity and temperature attenuation regularities of thermal jets are found. The study illustrates the practical value of numerical models for the examination of the discharge of thermal wastewater.
Centrifugal model test and numerical simulation of the breaching process of clay core dams due to overtopping
CHEN Sheng-shui, ZHONG Qi-ming, CAO Wei
2011, 22(5): 674-679.
Abstract:
The centrifugal model test system developed by the authors is employed to study the breaching process of a clay core dam due to overtopping. It is found that there are significant differences in failure mechanisms and the breaching processes between clay core dams and homogenous dams. With increasing erosion by overtopping flow downstream of the clay core dam, shear failure occurs and flood flow through the breach increases rapidly abruptly. Using the experimental result, a numerical model is developed to simulate the breaching process of clay core dams due to overtopping. The numerical solution of the model is discussed. In the model, an empirical formula derived from steep channel experiments with different soils is given. The formula can be used to calculate the erosion rate downstream of the clay core dam during the overtopping events. The mathematical relationship between the degree of erosion and shear damage is also obtained. The broad-crested weir formula is employed to calculate the dam-breaking flow. The proposed numerical model is validated by comparing the numerical simulation with the experimental data.
Mechanism of runoff generation on the sloped land of purple soil with different thicknesses in the Three Gorges Region
FU Zhi-yong, LI Zhao-xia, CAI Chong-fa, GUO Zhong-lu
2011, 22(5): 680-688.
Abstract:
Soil thickness is one of the most important factors determining the hydrological process on hillslopes. Using a portable rainfall simulator, file experiments were conducted on three sloped land sites along a hillslope to investigate the mechanism of runoff generation under artificial rainfall intensities of 60 mm/h. The sites contain purple soil with different depths (23 cm, 45 cm, and 76 cm). The results show that saturation excess runoff contributes a large portion of overland flow on the 23 cm soil site; it is in contrast with the domination of infiltration excess runoff generation found on other two sites. As for interflow, preferential flow is generated from the 23 cm soil site, while matrix flow dominates in the 76 cm soil site; two types of interflow zones are observed on the 45 cm soil site. And preferential flow is generated in upper soil horizon AC, while lower soil horizon A contains mainly matrix flow. The experiments reveal that the thickness of soil horizons and their hydrogeological properties play major roles in runoff generations.
Water-salt interactions factors and vegetation effects in the groundwater ecosystem in Yellow River Delta
AN Le-sheng, ZHAO Quan-sheng, YE Si-yuan, LIU Guan-qun, DING Xi-gui
2011, 22(5): 689-695.
Abstract:
To understand the function of the groundwater ecosystem in Yellow River Delta, some key aspects in the evaluation of terrestrial vegetation-groundwater interactions are examined using an integrated approach combining statistical, geostatistical, isotope, and 3S (GPS, GIS, RS) techniques. The examination focuses on the role of water-salt interactions and vegetation effects in the groundwater ecosystem. The results show that the shallow groundwater zone (1.0-3.0 m) in the study area is the main water source, indicating the crucial role of groundwater in the ecosystem. Both chloride ion concentration c(Cl-) and the total dissolved solids content (c(TDS))) in phreatic water present the characteristic of directional variability in space, or increasing along the direction of groundwater flow. The spatial distributions of c(Cl-) and c(TDS) are highly consistent with each other (R=0.999), showing that the quality of shallow groundwater is dominated by Cl-. The logistic relationship between Normalized Difference Vegetation Index (INDVI) and c(Cl-) in phreatic water reveals that the later is a curial control factor of groundwater in relation to the vegetation cover on land surface. It is therefore suggested that special attentions should be paid on the close relationship between vegetation and c(Cl-) in phreatic water in development of the Yellow River Delta High-efficiency Ecological Economic Zone, and the effective artificial regulation measures should be adopted to protect the ecosystem.
New calculation method for water-saving potential in agriculture based on water balance principle
LIU Lu-guang, CUI Yuan-lai, WANG Jian-peng
2011, 22(5): 696-702.
Abstract:
The water saving potential in agriculture plays an important role in scheme evaluation of water-saving performance, assessment of water use efficiency and optimal allocation of water resources. The evaluation indices and calculation methods are reviewed, and an innovative concept for water-saving potential in agriculture is proposed by taking into account water intake, water consumption and agriculture return water. The corresponding method for water-saving potential is given based on water balance principle. For different water-saving measures, the method can estimate the potential reductions in water intake and consumption, and the potential savings in agricultural return water. The new method is applied to the Liuyuankou Irrigation System (LIS) for a theoretical study on water-saving potential in agriculture. The result shows that the theoretical water saving in LIS could be as much as 4 636.59×104 m3. In which, the potential reduction in water consumption would be the largest, and followed by water intake and the potential savings in agricultural return water. The result provides a theoretical basis to the implementation for water-saving measures and effective utilization of water resources in LIS.
Dynamic simulation of nitrogen losses in surface runoff from farmlands using the DRAINMOD model
HONG Lin, LUO Wen-bing
2011, 22(5): 703-709.
Abstract:
In order to understand the mechanism and process of nitrogen losses from paddy field and upland field, field experiment was conducted in the Zhanghe Irrigation District, Hubei Province of China. The experiment was from June to September 2008, and a dynamic simulation of nitrogen losses in surface runoff from farmlands was carried out using the DRAINMOD model. Results show that both ammonium-nitrogen loss and nitrate-nitrogen loss in surface runoff from the paddy field are higher than those from the upland field. While the loss of ammonium-nitrogen from the paddy field will be higher than that of nitrate-nitrogen, and the opposite is true for the corn field (upland field). The simulated accumulations of nitrogen losses in surface runoff from both farmlands are in good agreement with the observations as revealed by low relative errors and high model efficiency coefficients. Over the paddy filed, the relative errors are respectively 8.35% and 10.99% for nitrate-nitrogen and ammonium-nitrogen; and the corresponding model efficiency coefficients are 0.961 and 0.974, respectively. These values are 5.45% and 14.11% for relative errors and 0.993 and 0.938 for model efficiency coefficients, respectively in the corn field. The study demonstrates that the DRAINMOD model is feasible and effective in the dynamic simulation of nitrogen losses in surface runoff from farmlands in this district.
Simulation of black bloom in Moon Bay of Lake Taihu and physical and chemical responses of water and sediment
SHEN Qiu-shi, SHAO Shi-guang, WANG Zhao-de, FAN Cheng-xin
2011, 22(5): 710-719.
Abstract:
Black bloom in Lake Taihu has become a matter of considerable concern in recent years. However, it is difficult to monitor the bloom timely and effectively, because the bloom may move from place to place and from time to time. The algae-originated black bloom in the Moon Bay of Lake Taihu was reproduced under indoor laboratory conditions in this study. The experiment used a Y-shape apparatus to simulate the sediment resuspension process. Quantitative changes in primary parameters both in overlying water and surface sediments were monitored during black bloom. The experimental data were analyzed. The result shows that the overlying water has undergone an oxic-hypoxic-anoxic period during the bloom. The dissolved oxygen (DO) level decreases from >6 mg/L at the beginning of the experiment to <0.5 mg/L after the black bloom. The water continues to darken until turned into black accompanying with a sudden burst of black bloom. The nutrient concentration in overlying water also increases steadily, which causes a heavy nitrogen and phosphorous pollution. Reduction of ferric iron (Fe(Ⅲ)) to ferrous iron (Fe(Ⅱ)) in surface sediments is greatly affected by the redox environment of water bloom, which creates a reducing environment (Fe(Ⅲ)/ Fe(Ⅱ) < 1) on the surface. At the same time, a sharp increase in acid volatile sulfides (AVS) in surface sediments is observable, and the maximum value of AVS (135.80 μmol/g) is found on the surface.
Experimental study on the simulation of freezing processes in calm waters and thermal changes on reservoir ice cover
TENG Hui, DENG Yun, HUANG Feng-bin, TUO You-cai
2011, 22(5): 720-726.
Abstract:
To study the freezing process and thermal changes on reservoir ice cover, icing tests were conducted with different air temperature and water depth conditions in the reservoir placed in a constant-temperature laboratory. The freezing time, the vertical distribution of temperature and the thickness of ice cover were measured during the tests to study the effect of different air and water depth conditions on freezing processes, thermal changes on reservoir ice cover, water temperature, and temperature distribution in the ice cover. The results show that temperature is a major influential factor on the ice cover regime. The ice thickness is linearly proportional to the accumulated hours under negative temperatures. The water depth has an impact on the onset of the freezing process, but its effect on thermal changes on reservoir ice cover is marginal. During ice growth, a linear temperature gradient can be observed in reservoir ice cover. The slope of ice temperature increases with the decrease of air temperature. The distribution of water temperature under reservoir ice cover remains unchanged during the melting period.
Application prospects of multi-model approach for modeling non-point source pollution
WANG Hui-liang, LI Xu-yong, XIE Ying
2011, 22(5): 727-732.
Abstract:
The problem of non-point source pollution has become an emerging issue associated with the implementation of effective control of point source pollution. The use of nonpoint pollution source models as an effective means of controlling pollution can provide valuable insight into the process of formation of point source pollution, and the subsequent migration and transformation, as well as pollutant loadings. However, the major challenge in single model approach to a catchment is the problem of uncertainty in pollution modeling. The multi-model approach has been successfully applied to hydrological modeling for dealing with uncertainty. Based on the analysis of similarity between hydrological models and non-point source pollution models, a multi-model approach for modeling non-point source pollution is proposed. The basic idea, key obstacles and challenges in the approach are also discussed.
Temperature as a groundwater tracer:Advances in theory and methodology
WU Zhi-wei, SONG Han-zhou
2011, 22(5): 733-740.
Abstract:
The theory and methodology of temperature as agroundwater tracer are reviewed. The focus is placed on related research about the temperature field and seepage field coupled modeling, the numerical simulation and the parameters inversion. A series of its applications are also presented from exchange between surface water and groundwater to groundwater leakage detection (taking dam as an example). The focus and difficult point of previous research is about fractured medium, unsaturated region, complex boundary, and non-Darcy seepage. In the future research, it is necessary to improve the models and the numerical solution techniques for enabling the models to meet the complex medium, complex hydrodynamic conditions and complex thermal environment. For the application of temperature as a tracer, it is more effectively to determine groundwater velocity by mathematical statistics method. And further quantify research on how to detect the position and feature of leakage by temperature should be done.