• 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. 6

Display Method:
Method for river functional regionalization and a case study
WU Yong-xiang, WANG Gao-xu, WU Yong-nian, FENG Hua-li, SHEN Fu-xin, LEI Si-hua, SHI Rui
2011, 22(6): 741-749.
Abstract:
River functional regionalization services as the precondition for exploiting the functionality in various rivers.In accordance with the characteristics of river functionalities and the requirements of basin management in China, the theoretical basis and principles for river functional regionalization are studied.As a result,a 4-layer classification system for river functional regionalization including the attribute-layer,the zone-layer,the index-layer and the man-agement-layer is established.The corresponding method and classification procedures are also presented.A case study is conducted on the Taipu River using the proposed method.The resulting river functional regionalization is presented and discussed together with the management objectives and strategies of the river.The result shows that the proposed method is sound and feasible,providing a new approach to the practice of river management.
Variational analysis of the relationship between wind and pressure of tropical cyclones in Northwest Pacific
ZHOU Guo-liang, ZHANG Jian-yun, LIU Jiu-fu, HUANG Chang-xing, LIAO Ai-min, DU Hong-juan
2011, 22(6): 750-755.
Abstract:
Using 60 years historical tropical cyclone (TC)data from 1949 through 2008,the relationship between the minimum TC central pressure and the maximum TC mean wind speed is analyzed in this study.As a result,a phase variation in TC characteristics is found.Further quantitative analysis on the variation is conducted.The result shows that an apparent inconsistency may exist in the wind-pressure relationship in the compilation of the 60 years TC data set,or the phenomenon of sequential variations.Specifically,two change points are found in 1971/1972 and 1974/1975,and the former is more pronounced than the later.Finally we recommend that it is better to use the lowest central pressure as the strength index for the study of TC historical variation.
Spatial interpolation of precipitation using the PER-Kriging method
WANG Shu, YAN Deng-hua, QIN Tian-ling, LIU Ru-hai
2011, 22(6): 756-763.
Abstract:
Based on the parameter-elevation regressions on independent slopes model (PRISM),a PER-Kriging in-terpolation method is developed to consider the effect of elevations on precipitation interpolation.The method can comprehensively consider the complex relationships between grid points and observational sites in locations,horizontal distances and elevations.The method uses a reference elevation in precipitation interpolation in order to practise easily. The performance of the method is enhanced through nonlinear refitting of the elevation-precipitation relationship obtained by linear fitting scheme.Both PER-Kriging and Ordinary Kriging methods are tested on the Lancangjiang basin for precipitation interpolation and results are compared with each other.The result shows that PER-Kriging can effectively eliminate the errors introduced by the large geographic differences and the smoothing processes.Compared to Ordinary Krijing,the PER-Kriging method can reduce the mean error of interpolated precipitation by 20 mm,and the relative errors in different types of curve fitting are less than 12%.
Comparisons of hydrological variations and environmental effects between Aral Sea and Lake Balkhash
GUO Li-dan, XIA Zi-qiang, WANG Zhi-jian
2011, 22(6): 764-770.
Abstract:
Abstract:Using both qualitative and quantitative methods this paper investigates the similarities and differences of the Aral Sea and Lake Balkhash through analyzing the hydrological characteristics,runoff features of the main inflow rivers,human activities in the catchments,related eco-environmental issues and the future trends.The results show that,the water level in the Aral Sea decreased sharply since 1960,until a nearly single trend of water level variations.The entire water body of Aral Sea was splitted into four areas by 2009.On the other hand,the water level fluctuations in the Lake Balkhash followed a cyclical pattern over the long term,especially,the water level had been dropping since 1970 and reached a minimum value in 1987.The study reveals an unsatisfactory situation in the hydrological regime of Aral Sea,as the entire water body may eventually dry up in the near future.The water level condition cannot be ignored in Lake Balkhash,as it is currently undergoing a change from water surplus surplus to shortage.The study recommends that all the riparian countries including the Aral Sea and Lake Balkhash should have an important responsibility in the protection of transboundary water resources and eco-environment conditions.
Flood control operation chart for Three Gorges Reservoir considering errors in inflow forecasting
LIU Xin-yuan, GUO Sheng-lian, LI Xiang, LI Yu
2011, 22(6): 771-779.
Abstract:
The daily inflow forecast results of the Three Gorges reservoir (TGR)were analyzed,and the probability density functions of inflow forecasting relative errors with lead-times were estimated by using the nonparametric estimation.Considering the power generation and navigation,a flood control operation chart model was developed based on the inflow forecasting information.The proposed model was solved with a differential evolution algorithm.By comparing the results of different forecasting schemes,the impact of forecasting errors on flood control operation was analyzed.It is shown that the optimal reservoir flood control operation chart based on the current forecasting scheme can generate 5.3% extra hydropower energy,save 6.9% flood water resources,increase the flood peak clipping ratio by 1.7%,and the capacity to withstand the risk of 1000-year design flood can be also greatly increased.
Multi-objective optimization model for ecological operation in Three Gorges cascade hydropower stations and its algorithms
LU You-lin, ZHOU Jian-zhong, WANG Hao, ZHANG Yong-chuan
2011, 22(6): 780-788.
Abstract:
A multi-objective optimization model for ecological operation in Three Gorges cascade hydropower stations is proposed.The model considers the restrictive relationship between power generation and ecological restoration in Three Gorges,and balances the needs of competing interests of power generation and ecology.The objective functions are designed to maximize power generation while minimizing ecological water requirements,for which a multi-objective differential evolution (DE)algorithm is proposed.The evolutionary operators in the DE algorithm are modified according to the inherent nature of multi-objective optimization problems.A local chaotic search strategy is designed to perform multi-objective optimization,thus solving the problem of premature convergence in the DE algorithm.A non-penalty-based constraint handling algorithm is proposed to handle complicated problems in multi-objective optimization for ecological operation.The model is applied to the optimized ecological operation in Three Gorges cascade hydropower stations.The result demonstrates the effectiveness and practicality of the proposed model in engineering applications.
Summer low-flow response to forest cover change in small-sized watersheds of Northeast China
YAO Yue-feng, MAN Xiu-ling, CAI Ti-jiu
2011, 22(6): 789-794.
Abstract:
Abstract:The summer low-flow response to forest cover change in the small-sized Yulingou watershed of Northeast China was analyzed using two graphical methods (the double mass curve (DMC)and the low-flow duration curve (LFDC)).The low-flow data is obtained from the 32 summer periods (June-August)of 1973-2004 and used for deriving the flow duration curve (FDC).Compared to the baseline the period 1973-1982,there is a 15% increase in forest covers during the period 1983-2004.The latter is the result of reforestation activates.Although,the average of summer low-flow discharges has gone up by 11.84% during the latter period,the annual rate of discharge increases has been in steady decline since 1983.The reforestation had the most impact on the increase of summer low-flow discharges for percentiles between 0 to 50 on the LFDC,which demonstrates the important role of northeastern forests in enhancing summer low-flow discharges.The strength of enhancement began to decrease after the forest cover reaching 70%.Thus,a 70% forest cover should be maintained on the Yulingou watershed for the sustainable development of forest industry and water resources.The LFDC method could be applied for analyzing the effect of forest cover change on specific percentiles of summer low-flow discharges.
Slope of evaporation lines in a model based on Rayleigh fractionation formula
WANG Yong-sen, MA Zhen-min, XU Zheng-he
2011, 22(6): 795-800.
Abstract:
The Rayleigh fractionation formula is an important method to study the isotope variation in water bodies under the influence of evaporation.The influencing factors on the coefficients of the Rayleigh fractionation formula are analyzed.A model based on the formula is solved for the slope of evaporation lines in water bodies.The influence of humidity and temperature on the slope is analyzed.The result shows that the slope of evaporation lines would reduce with the increase in humidity,and it would become larger with the increase in temperature.Using humidity and temperature data,the model is applied and validated on the middle reach region of the Yellow River Basin.The simulated slope of evaporation lines is compared with the surface water isotope data.
Development and application of a fuzzy membership model for identifying erosive rainfall events
SUN Zheng-bao, CHEN Zhi-jian, LIAO Xiao-yong, WANG Hai-ming
2011, 22(6): 801-806.
Abstract:
Soil erosion caused by rains is a continuous process of changes.Such a soil erosion character is used in the development of a fuzzy membership model for identifying erosive rainfall events.The precipitation amount (P)and the maximum 30 min rainfall intensity (I30)of a rainfall event are used as two physical parameters in the model.The model involves three parts.The first part calculates the membership values of P and I30,and constructs the fuzzy membership functions.Secondly,the membership values of P and I30 are combined to form a new membership value of individual rainfall event.And finally,an erosive rainfall event is identified using the new membership values.The identified events can be validated through the mistaking degrees and the missing degree.The model is applied over three small-sized watersheds in the Three Gorges Reservoir region of southwest China,including Chenjiagou (8.32 km2),Daijiagou (0.67 km2),and Qiaojia (0.02 km2).The mistaking degrees on the three watersheds are less than 20%.The model has a simple structure,and its parameters have clear physical meaning and can be derived directly from the hydro-meteorological observations.
Riverbed evolution in the Yichang-Changmenxi reach downstream of Three Gorges Reservoir
LUO You, CHEN Li, XU Wen-sheng, SU Chang
2011, 22(6): 807-812.
Abstract:
An index K,which stands for the extent of riverbed evolution,is proposed and used to analyze the riverbed evolution in the reach of Yichang to Changmenxi.The study finds that K is inconsistent with the net scour intensity,while positively correlated to the ratio of width to depth and negatively correlated to the median diameter of bed material when the diameter is less than 0.5mm.Preliminary analysis shows that:it is easy to reach the state of transport saturation for coarse sediments downstream of the Three Gorges Reservoir.And the coarse sediments deposit when transport capacity decreases,causing great local deposition on wide-shallow river channels and the net scour intensity decreases,and riverbed evolution strengthens.When the median diameter is less than 0.5mm,the suspend loads is dominant in the downstream scouring amount,resulting that:the finer the bed material is,the greater the scouring a-mount and the riverbed evolution is.Considering the changes of capacity of sediment transport along the river reach after dam construction,two ways of coarsening the river bed are discussed.
Preliminary study on the analytical model for slide collapse of riverbanks
JIA Dong-dong, ZHANG Xing-nong, YING Qiang, CHEN Chang-ying, ZHANG Si-he
2011, 22(6): 813-817.
Abstract:
The slide collapse of riverbanks with fast-developing,large rates of bank erosion,and strong destructive powers is a common type of riverbank collapses in alluvial rivers.This type of failure is mainly caused by the directimpact of flow water,as well as resulting from the fact that water level is too close to the top of riverbanks in the course of collapse.An analytical model for the slide collapse of riverbanks is presented based on the analysis of scouring effects on the riverbanks.The model structures and parameters are evaluated using the flume experiments and centrifugal tests.The erosion coefficient of river bank is calibrated using the experimental data.The model result is in good agreement with the experiments.The analytical model contains only a few parameters and is easy to apply.The model result can be used as a reference for the prediction of riverbank erosion and channel migration.
Monitoring and estimating non-point source pollution on typical sections along the Weihe River
LI Jia-ke, LI Huai-en, SHEN Bing, QIN Yao-min, DONG Wen
2011, 22(6): 818-828.
Abstract:
The water quality of the Weiher River is heavily affected by non-point source pollution (NSP).It is there-fore necessary to quantify NSP loading.We monitored both water flow and water quality at two cross-sections along the Guanzhong river reach near the cities of Xianyang and Lintong for two flooding and non-flooding seasons of 2009 and 2010.The measured parameters include chemical oxygen demand (COD),dissolved orthophosphate,total phosphor-us (TP),TP,NH3-N,NO2-N,NO3-N and total nitrogen (TN).NSP loadings are calculated using the modified hydrological division method and the mean concentration method.The latter is proven to be a well-established and widely-used method.The results show that COD,NH3-N and TN constitute the majority of pollutants in the Guanzhong reach.Their mean concentrations are lower but more variable during flooding seasons compared to that of non-flooding seasons.The concentration is inversely proportional to the scale of the floods in the reach.The NSP sim-ulations using the two methods agree well each other,indicating the applicability of the hydrological division method when data is scarce.The two simulations reveal that NSP accounts for about 20% to 30% of the total pollutant loading at the two cross-sections in 2009 (a dry year with P=68%).Thus,point source pollution (pollutants discharged from the cities of Xianyang and Lintong)is the main contributor to the water pollution problem in the Guanzhong river reach,as it contributes more than 80% of the total loading.However,compared to 2006 other dry year with P=69%,the point source loadings of COD,NH3-N and TN are actually reduced by 11 937 t,791 t,and 29 t in 2009. This shows the effectiveness in controlling point source of pollution in the Weiher River.In addition,the overall com-position of pollution remains almost unchanged in 2006 and 2009,and NSP gives a substantial contribution to water pollution,which cannot be ignored.
Analysis on partial pressure of CO2 and influencing factors during spring phytoplankton bloom in the backwater area of Xiaojiang River in Three Gorges Reservoir
GUO Jin-song, JIANG Tao, LI Zhe, CHEN Yong-bo, SUN Zhi-yu
2011, 22(6): 829-838.
Abstract:
Monitoring of the partial pressure of CO2 (p(CO2))was conducted in the backwater area of Xiaojiang River in Three Gorges Reservoir.Water samples were taken from the five cross sections in the Quma-Heikou reach of Xiaojiang River during the spring phytoplankton bloom from April 10 through May 25,2010.Results show that there are obvious stratifications of chlorophyll a (Chla),dissolved oxygen (DO),and p(CO2)in water columns.The value for p(CO2)is low in surface water due to phytoplankton photosynthesis effects.The surface water can be the CO2 sink if sufficient sunshine presents.A minimum value of 4.3 Pa for p (CO2)was observed from the cross section of Shuangjiang on April 25,with an absorption flux of -0.28 mmol/m2/h.The value for p(CO2)increases vertically with the water depth,and will be stabilized in the 10-15m layer of water.The partial least squares regression analy-sis reveals that the growth and metabolism of phytoplankton in the surface water are the key factors controlling p(CO2).A negative relationship between the water temperature and p(CO2)has been found,but its influence on p(CO2)is minimum.Using the indices of Excess p(CO2)(Ep(CO2))and apparent oxygen utilization (ADO),a three-stage bloom of phytoplankton in the Xiaojiang River was observed,during which,the surface water had gone through a sink-source-sink cycle for CO2.
Relation of total dissolved gas supersaturation and suspended sediment concentration of high-dams
QU Lu
2011, 22(6): 839-843.
Abstract:
In order to resolve the issue concerning the relation of total dissolved gas (TDG)supersaturation and sus-pended sediment concentration of high-dams,a practical abatement measure for TDG supersaturation is put forward in this study.Based on a series of experiments,the production and release of TDG supersaturation in sediment laden flow are studied.The result shows that the production of TDG supersaturation remains almost the same level in either sediment laden flow or clear water for the same initial conditions.The rate of release of TDG supersaturation in sediment laden flow is significantly faster than that in clear water.The suspended sediment concentration can be increased through the use of bottom intakes,speeding up the release of TDG supersaturation.Such a measure can minimize the effect of TDG supersaturation on fish species in the downstream region of high-dams.
Thermal stratification and its influence factors in a large-sized and shallow Lake Taihu
ZHAO Lin-lin, ZHU Guang-wei, CHEN Yuan-fang, LI Wei, ZHU Meng-yuan, YAO Xin, CAI Lin-lin
2011, 22(6): 844-850.
Abstract:
Thermal stratification is an important factor controlling nutrient cycling and phytoplanton production in the aquatic ecosystem.To highlight the stratification characteristic of water temperature and its influence factors in large-sized and shallow lakes,the annual variation of stratification of water temperature was investigated in Lake Taihu using the thermal chain.The analysis of 6-layer water temperature data at the 2.5-m water depth shows that the vertical difference of water temperature in Lake Taihu is generally ranged between 0 and 1℃,but short-term ones also could reach high values between 1 and 4℃,even over 4℃ under the extreme condition.Furthermore,the vertical temperature difference in Lake Taihu varies with seasons,months and days,and the corresponding thermocline depth also changes.The many factors such as solar radiation,air temperature,wind speed,water density,specific heat and cyanobacterial bloom and others impact on thermal stratification.With the increase of solar radiation intensity,the vertical profile of water temperature rises at first and then dips.The maximum temperature appears when the peak solar radiation value of about 700 W/m2 occurs.The thermal stratification weakens as the wind speed increases.However, the stratification will be stabilized when the wind speed exceeds a threshold value of 4m/s.This is especially true in summer and autumn seasons.The quicker the change in air temperature is,the larger the difference in water temperature.The inversion layer may occur during cold winder seasons due to the variation of water density and specific heat. The period of strongest stratification occurs in summer due to cyanobacterial blooms.The study indicates that transient thermal stratification can be found in a large-sized shallow lake that is subjected to frequent hydrodynamic disturbances.The stratification characteristics of water temperature are affected by meteorological conditions.The study provides insight into the internal nutrient release process and highlights the mechanism in cyanobacterial blooms.It also provides valuable information for creating the lake ecological model.
Numerical simulation of influence of transition section on continuously curved channel flow
HU Xu-yue, ZHANG Qing-song, MA Li-jun
2011, 22(6): 851-858.
Abstract:
The length of transition section is an important parameter of continuous meandering rivers,which has a profound influence on the flow regime in the second bend.Based on the experimental results from the physical models,an air-water two-phase flow model is derived for flow simulation in the continuous bends.Both re-normalisation group (RNG)k-epsilon model and volume of fluid method (VOF)are used in the model derivation.Through inspec-ting various flow regimes due to different lengths of transition sections,it is found that the effect of flow in the front bend on the second bend can be weakened when the length of transition section increases.However,the flow in the second bend will be stabilized when the length exceeds a threshold value.The front bend has a neglectable influence on the flow in the second bend thereafter.Thus,a critical length of transition section can be defined,which can be used as the base value for the design of transition section in practical application.
Mathematical modeling of non-cohesive earth dam breaches
WANG Li-hui, PAN Cun-hong, WU Xiu-guang, PAN Dong-zi, YU Pu-bing
2011, 22(6): 859-863.
Abstract:
A mathematical model of overtopping dam-break is developed using the coupled 1D shallow water equations on steep surface and the Exner equation.The model takes advantages of the Roe approximate Riemann solvers and the predictor-corrector scheme for the source term treatment.The issues of computational stability and accuracy on sediment erosion transport and bed evolution can thus be ensured.The result shows that the model is able to better simulate the process of non-cohesive earth dam breaches and provides a new approach for numerical modeling of overtop dam-break.
Advances in hydrological frequency analysis of non-stationary time series
LIANG Zhong-min, HU Yi-ming, WANG Jun
2011, 22(6): 864-871.
Abstract:
The conventional methods of flood frequency analysis are based on the assumption that the hydrological time series is statistically independent and identically distributed.The latter assumption implies that the series is subject to a same distribution in the past,present and the future,i.e.the series should be consistent.However,this as-sumption is usually not valid because of the impacts of climate change and human activities on hydro-meteorological conditions.Therefore,it is necessary to develop new approaches for frequency estimation of non-stationary time series of extreme values.The advances in the subject are presented in this study.The recent development has focused largely on the following two aspects,i.e.,the approach based on the backward restore or forward restore,and that directly based on the non-stationary hydro-meteorological extremes.Finally,perspectives on the hydrological frequency analysis of non-stationary time series are prospected.
Review of scale effect on the irrigation water use efficiency
CHEN Hao-rui, HUANG Jie-sheng, WU Jing-wei, YANG Jin-zhong
2011, 22(6): 872-880.
Abstract:
A comprehensive review of scale effect (SE)on the irrigation water use efficiency (IWUE)is presented in this study,including the definition and its causes as well as the upscaling techniques.SE is the composite outcome of two main causes that refer to reusing irrigation return flow and the spatial variability of local properties such as soil, crop,climate,irrigation structures,and amount of irrigation water and others.The existing indices of irrigation water use efficiency should be extended to including the connotation of water supply efficiency.Reusing irrigation return flow should be considered together with the economic constraint.The existing studies on scale effects show that the regularity with regard to indices of irrigation water use efficiency is not conclusive due to the complexity of nature conditions.Regarding to upscaling problem,the two main causes have been taken into account separately and need to be synthesized in the future studies.A reliable and practical upscaling formula is still unavailable for use to improve the practice of water management.Many efforts should be devoted to the theory of scaling as well as the scale effect of accompanying courses with the water cycle,based on the improvement of irrigation water use efficiency assessment indices.