The relationship between total phosphorus (TP), water clarity (SD, called Secchi disk depth) and chlorophylla in the Three Gorges Reservoir Area-including 16 tributaries and 35 big or middle reservoirs in Chongqing City-was studied. The chlorophylla concentration in the Three Gorges Reservoir Area after impoundment was predicted by using the TP and Chlorophylla relationship based on the present TP concentrations in 40 branch stream estuaries at dry seasons in 1998. The trend of eutrophication in the Three Gorges Reservoir was analyzed by the predicted chlorophylla concentration. It is shown that the reservoirs at tributary rivers, most of which were in a high trophic status, exhibited a good relationship between chlorophylla concentration and TP concentration and water clarity. In some natural branches such as Wujiang river, the concentration of TP and chlorophylla showed no obvious relationship even in algal bloom condition. It is shown that the current status is the key reason for water eutrophication in the Three Gorges Reservoir Area. It is predicted that algal bloom may occur in some water areas in the reservoir after the completion of Three Gorges Project.

Based on the fundamental theory of computing hydraulics and the twodimensional mathematical model of water flow, a numerical simulation of river flood carrying capacity was carried out. Using SMS (Surface Water Modeling System) software, the fluctuation range of flood level was simulated respectively, when the wetland was of different area, width and vegetation roughness coefficients. It is showed that the variation of the wetland width, which led to flood level fluctuation, could be finally summarized to the variation of the river channel width. And the variation of the channel width has more significant influence on the fluctuation of flood level than that of wetland area and roughness coefficients of wetland vegetation. Also it can be concluded that the narrower the width of the channel is, the higher the flood level rises. Certain suggestions were provided for the arrangement of wetland and the selection of wetland vegetation in rivers.

The problem of warm water drainage is a typical problem in environmental hydraulics. To study the distribution condition in current field and temperature field of warm water drainage kinetics is of great scientific significance in respect to the design of warm water drainage engineering, the prevention of warm water pollution, and the protection of environment. A twodimensional numerical model, which is in the curve coordinate, was applied to simulate the problem of warm water drainage in continuous bends. By comparing the thermoisopleth chart of three different kinds of discharge-left bank, right bank, and center discharge-at the same velocity ratio in continuous bend and the thermoisopleth chart of different velocity ratios in the same discharge, it is indicated that the numerical model established in this paper can reasonably reflect the kinetic law of warm water drainage and can be used to simulate warm water drainage process.

To study the influence of lowtemperature water of hydropower projects effluent on water temperature distribution and aquatic ecosystem in the downstream of a dam, the water temperature distribution in the reservoir and the effluent water temperature at three different intake locations were predicted using laterally averaged twodimensional model in this paper. It is shown that the effluent water temperature from March to August decreased with the decrease of intake elevation, while from September to February in the following year increased with the decrease of intake elevation. It can be concluded that to a certain extent, layered intake can reduce the difference of water temperature between effluent and natural water, and mitigate the adverse effects of lower temperature effluent on aquatic ecosystem in the downstream of a dam. This study can provide a theoretical base for the assessment of environmental impact of water hydropower projects.

To understand the formation and change of non point source pollution is the first important step to controll and manage non point source pollution. There is a wide range of non point source pollutants in the Three Gorges Reservoir. Every year, nonpoint source pollutants discharged into rivers from the upper reaches contribute the major part of non point source pollutants in the Three Gorges Reservoir. In order to study the pattern of change in non point source pollutants in the Three Gorges Reservoir, the model of non point source pollution load from the upper basin of Chongqing Cuntan section of the Yangtze River was established on the basis of the SLURP model and the Export Coefficient Approach. At last, using the established model, nonpoint source TN and TP annual load from upper basin of Cuntan section were calculated and simulated for the period from 1996 to 2002. Except the more than 50% calculation error for non point source TP load in 1998, all other calculation errors were less than 30%. It is considered that the model can provide a good fit to the observed data, and that the established model for non point source pollution and its application in the Yangtze Basin will be valuable for the management and control of nonpoint source pollution, and may form a base for making policies on pollution control.

The adsorption and desorption behavior of phosphorus on particles in the Three Gorges Area was studied by synchronous monitoring and laboratory experiments. Monitoring experiment revealed a close relationship between phosphorus concentration and particle content. Laboratory experiments were carried out in isothermal adsorption equilibrium and kinetics by mixture particles, the size of which was classified by D1≤0.020 mm and D2≤0.008 mm. The isothermal adsorption equilibrium experiments showed that the particle size has great effect on adsorption amount, with the adsorption amount increasing with the decrease of particle size. The data from kinetics experiment fitted by the secondorder kinetics equation showed that the kinetics coefficient was affected by particle size, particle content and phosphate concentration. Under the condition of the same particle content and initial phosphate concentration, the kinetics coefficient was greater on thinner particles. Adsorption and desorption experiments were carried out by using particles from Cuntan crosssection. The adsorption experiment data can well be fitted by Langmuir kinetics equation, with rate coefficient k being greater on the coarser particles, and initial phosphate concentration having no obvious effect on rate coefficient k. The desorption experimental data fitted by Langmuir kinetics equations showed that the phosphate desorption amount decreased with the increase of particle concentration and particle size, and rate coefficient k decreased with the increase of particles size. There was no obvious effect of particle size on coefficient k.

The desalination industry is undergoing a fast development in the world due to water shortage and significant reduction in production cost in recent years. For environmental concerns, a proper design of the brine outfall is essential to enable the end discharge mix rapidly with the ambient coastal waters. A widely adopted practice is an inclined round submerged discharge at the seabed, with an inclination angle of 60° to the horizontal to optimize the mixing efficiency. However, the maximum rise height associated with 60° is relatively large and thus unsuitable for disposal in shallow coastal wasters. In this study, the authors investigated the mixing efficiency of a submerged round brine discharge at smaller angles (30° and 45°) by using advanced laser diagnostic approach of combined Particle Image Velocimetry (PIV) and Planar Laser Induced Fluorescence (PLIF). Based on the experimental results, characteristic geometrical features were identified in dense discharge flow, such as terminal rise height and horizontal location and dispersion degree of the impact point, where the downward flow impinges the base. The results may be of regulatory reference for the mixing pattern of the brine plume in surrounding coastal waters.

The impact pressure of swirling jets, produced by watercushion swirling abrasive jet nozzle, was measured by continuous shooting images of the symbol in the piezometer tubes. Based on computer image processing technology, the development of dynamic impact pressure under different inflow conditions was obtained automatically. It is shown that the flow rate ratio of tangential inflow to axial inflow and total flow rate were the control factors of the impact pressure, with the former determining the distribution and scale of the impact pressure, while the latter determining the scale only. Moreover, the influence of flow rate alteration of the tangential inflows from four directions upon the timeaveraged pressure was rather little, and the fluctuation of the dynamic pressure became small as the distance between the gaging point and jetcore increased.

In order to develop a fast way for monitoring chlorophylla concentration in Lake Dianshan of Shanghai, the reflection spectra in spring of 2006 was measured with simultaneous sampling and analysis,and the correlation between chlorophylla concentration and reflection spectra was studied on the basis of different chlorophylla algorithms. The accuracy of the linear algorithm using the normalized reflectance is not high (R2<0.6). The relationship between chlorophylla concentration and the bandratios R708/R667 can improve the accuracy (R2=0.68). The exponential algorithm between chlorophylla concentration and the first order differential of the reflectance at 695.5 nm is good (R2=0.76). Multivariate regression models with the normalized reflectance at 708 nm and 607 nm and their logarithm were also established with a higher accuracy, and the best model was achieved with the logarithm at 708 nm and 607 nm (R2=0.8).The present study thus demonstrated the potential of monitoring chlorophylla concentration by using hyperspectral remote sensing technology in inland waterbody.

According to the characteristics of water pollution in Taihu Lake, this paper summarized major causes of water pollution such as slow water flow, stagnant water exchange, small contamination capacity and pollutants entered into the Meiliang Bay exceeding its environmental capacity, and then proposed key strategies and techniques for water pollution control such as regional comprehensive treatment, total amount control of contamination, and water diversion and regulation. With the application of 2D hydrodynamic and water quality models, the amount of water pollutant capacity in Meiliang Bay of Taihu Lake was calculated. In consideration of water diversion from the Yangtze River to Taihu Lake, this study simulated the effect of water diversion to Meiliang Bay on the water environment. In order to optimize the regulation of the water diversion, the effect of largescale and smallscale diversion was forecasted and compared. The results obtained in the present study may provide scientific bases for water pollution control in Meiliang Bay of Taihu Lake and other similar water bodies.

Water pollution may cause disputes between districts and provinces, and has been one of the most serious environmental problems in China influencing seriously the economic development and social stabilization. The establishment of mechanism for the compensation of water pollution between different parties may enable pollution distributors to measure the disposing and compensation cost. The establishment may also favor internalization of the external environment pollution and promotion of the effective implement of pollution control. Therefore, it will help to resolve the water pollution discordance. On the basis of assessing economic loss due to water pollution, this paper employed water environment model to describe the spatial impact of pollutant discharge in rivers. In consideration of the environmental and economic effects of pollutant discharge, a theoretical model for water pollution compensation in rivers was proposed, with its basic characteristics, processing methods and application conditions discussed in the paper.

〖WT5BZ〗〖WT6BZ〗() 〖JZ)〗〖WT5HZ〗Abstract: 〖WTBZ〗Previous research has shown that about 16 percent phosphorus in water body comes from the use of detergents. In order to protect the water environment of the Three Gorges Reservoir, and to prevent water eutrophication, Chongqing municipal government declared that phosphorus should never be used in detergents since 1st January, 2003. The average phosphorus content in detergents containing phosphorus is about 4 percent, and the content in detergents without phosphorus is about 0.013 percent. After being banned in detergents, the phosphorus content of detergents reduced about 99.7 percent averagely. Monitoring data revealed the reduction in total phosphorus concentration in urban wastewater. The decrease proportion in phosphorus content in central city zone is about 15.12%, in medium city about 18.36% and in county side about 33.66%. Before being banned in detergents, the phosphorus from detergents accounted for 13.77％ in total phosphorus concentration of urban wastewater, and after that the phosphorus from detergents accounted for only 0.05％. Before being banned in detergents, the phosphorus from detergents accounted for 30.53％ in total phosphorus concentration of rural wastewater, and after being banned it occupied only 0.01％. Based on the total phosphorus concentration of urban wastewater and the amount of detergents actually used by per person, about 1 056.2 t·a-1 phosphorus was cut off in urban wastewater after being banned in detergents in the urban area of Chongqing City; while 1 203.8 t·a-1 phosphorus was cut off in wastewater discharged directly to rivers in countryside.

Based on the review of relevant theories and practices in river conservation and restoration all over the world, the authors proposed that a proper ecological target should be set up to meet the primary need in river conservation and restoration. The target should be quantified for practical direction for river management and restoration. For this purpose, a recently developed method of DRIFT is briefly introduced in the paper, and the classification of ecological conservation level or grade was also analyzed. In consideration of the present situation in China, it is suggested that we should make out the ecological functional division of rivers,plan and set various conservation targets for different rivers,and confirm corresponding conservation levels so as to enforce river conservation and restoration.

Hydropower projects built for social and economical development of a country may have various effects on aquatic ecology. It is thus both scientifically and socially important to evaluate the changes of hydrological processes in relation to this kind of projects. An index system was set up in this paper, including six ecohydrological characteristic indexes, that is, longterm variables, highflow variables, lowflow variables, movingaverage variables, variables related to the rise and fall of the hydrograph and monthly flow variables. By using the index system, changes in hydrological processes can be evaluated. The index system was applied in this paper to evaluate the changes of ecohydrological characteristics in the middle reach of the Yangtze River after the construction of Gezhouba hydropower project. It is shown that the construction and operation of Gezhouba Dam has obvious influence on the variables related to the rise and fall of hydrograph.

The temporal variability of daily discharge from 1900 to 2004 in Yichang Gauge, which is located in the upper reaches of the Yangtze River with a catchment area over 1 million km2, has been analyzed in the present study. The MannKendall statistical test was applied to assess the significance of the trends. There is a decrease trend in annual and monthly discharge series, and the trend is significant at annual level and in February, August, October and November with the decrease significance exceeding 95% confidence. The MannWhitney statistical test was also applied to assess the jump of trends. A jump happened in 1969 with the confidence exceeding 99%, and the difference of mean discharge before 1970 and after 1970 is 937 m3/s (6.5%). The Range of Variability Approach (RVA), which contains thirtytwo ecohydrological parameters called Indicators of Hydrologic Alteration (IHA), was used to evaluate the flow conditions before and after 1970. 25th to 75th percentile values for each parameter before 1970 was set at the management target range. It is shown that light hydrological alternations are observed for most parameters, except five parameters including monthly discharge and rate/frequency of water condition changes parameters in January and November. The hydrological alternation is mainly due to the decrease in precipitation and the construction of dams in the upper Yangtze Basin.

The authors proposed the ecohydraulics in calculating the lowest ecological flow in river channels to resolve ecological water demand of Jinping Waterpower Station Stage II (Jinping II) reducing reach. The lowest ecological flow in river channels was determined by satisfying hydraulic habitat of objective aquatic biology. The change in hydraulic habitat parameters in whole reducing reach was considered and the conception of the percentage of cumulated river length to the reducing reach length in fulfilling the hydraulic habitat parameters was put forward. The gained results avoid the misjudgment conduced by using lower parameter value when the percentage of the length of reducing reach to the total is very small. Referring to the characterization of hydraulic habitat parameters in related literature, using specific situation of fish habitat in Jinping II reducing reach of Yalong River, the authors confirmed the fish habitat requirements to various hydraulic parameters, such as velocity, water depth, water surface width etc. It is indicated that the lowest ecological discharge in the reducing reach in dry seasons is 45 m3/s in order to meet the subsistence of fishes. 95 percentage of river channels can satisfy the hydraulic factors for the subsistence of fishes, including water depth, velocity, water surface width, wetted perimeter ratio, cross section area, and water surface area. The change of water temperature will not affect fish spawning in 45 m3/s. The places of hydraulic forms including torrent, subcritical flow, riffle and deep pool will change, yet their amount will remain the same as in 45 m3/s. When the river discharge reduces, the biomass will reduce. However, the amount of animal community will remain as long as the river discharge exceeds 45 m3/s. This method provides feasible means to determine the flow for ecological requirement of fishes in river channels.

From October 2004 to May 2006, hydroacoustic survey on fishes was carried out in the 30 km reach from Gezhouba Dam to Gulaobei in the Nature Reserve for Acipenser sinensis Gray in the Yangtze River with Bisonics DTX Scientific Echosounder (200 kHz). Fishes were distributed not homogeneously, being assembled in deep pools but rarely in saults. Mean densities of fishes in the reach from Gezhouba Dam to Aijia River were obviously greater than those in the reach from Aijia River to Gulaobei. In spawning period of Acipenser sinensis Gray, fishes congregated in the reach from Gezhou Dam to Miaozui, with mean densities being 62.62 ± 24.77 ind./1 000 m3 in 2004 and 70.58 ± 37.45 ind./1 000 m3 in 2005. The proportion of fishes with the body length ranging among 60 mm and 106 mm was higher than other length groups along the reach, accounting for approximately over 7.0% of the total fishes. Moreover, the ratio of fishes with body length less than 53 mm and longer than 750 mm were lower than other length groups in the reach, accounting for less than 2.0%. During the survey period, spawners of Acipenser sinensis Gray were found, with 1 453 estimated in 2004 and 789 in 2005, at 95% confidence limits of 1 370~1 537, 775~803 respectively.

 Traditional hydraulic engineering has some deficiencies such as the ignorance of integrality and ecological function of the watershed, resulting in unavoidable negative effects on the watershed ecosystem and the sustainable development of resources. Therefore, the concept of ecohydraulic engineering is proposed. With basic thoughts to resolve the problem and to achieve harmonious coexistence of human and nature, we should insist on sustainable development, keep selforganization and selfrestoration of ecosystem, attach importance to the integrality of watershed, preserve the diversity of biology, and maintain water accessibility; thus we can construct the basic principles of ecohydraulic engineering. Moreover, the health check of the watershed ecosystem, design and management of the ecohydraulic structures, and ecological restoration and reestablishment of damaged watershed ecosystem are the main research aspects for the construction of ecohydraulic engineering.

The authors analyzed disadvantages in traditional designing and building of natural river levees at first, and then briefly introduced the ideas of ecological management for the stream corridor. In particular,the constitution and characteristics of ecosystem in natural levee, and multifunctions and landscape connotation of natural levee are introduced. It was suggested that in designing and building natural levees, on the premise of security and stability, the construction and protection of ecosystem should be put in the first place, and the landscape and water affinity of natural levees should also be recognized. The selection of construction material vegetation communities was also analyzed. This paper can provide some ideas to specific projects such as construction of natural levee and management of stream corridor and flooded area.

The investigation object of this paper is the Daninghe River Basin in the Three Gorges Reservoir Area. Based on theories of ecosystem health and the model of PressureStateResponse built by the Organization for Economic Cooperation, the indicator system for ecosystem health assessment of Daninghe River Basin was established. This paper adopted some data of remote sensing with other auxiliary data to distil information of ecosystem. Based on the assessment unit of small watershed, the individual index and comprehensive index were evaluated. It is indicated that the condition of ecosystem health in the Daninghe River Basin has the characteristic of vertical distribution.

This paper introduced quantitative approach to detect the change in land cover within 10 years before and after the construction of Three Gorges Reservoir. The Land Cover Classification System of Food and Agriculture Organization of the United Nations is available to divide 38 types of land cover at the scale of 150 000. It is indicated that the farmland accounted for 43.93% of the total land cover in the Three Gorges Reservoir area, and forest area for 29.03%. In Comparison with the land cover in 1992, the farmland reduced 1.13%, forest area reduced 0.13%, and the shrub area increased 0.58%. The factors influencing land cover change are mainly related to urban development, reservoir immigration, and policy of local ecology and environment.

Traditional ideology for river regulation is to build the dyke and lake gates along rivers for flood defence. Such modes have obstructed the connexity between rivers and the round lakes, and caused the shrinking of wetland. To improve and protect the wetlands bioenvironment and biodiversity, the new multipurpose mechanism of gate management is proposed for the recovery of the connexity. Also management measures for impact zones are suggested to make the new mechanism into effect, and the management of Zhangduhu Lake is discussed as an example.

Many lakes in Jianghan Plain have lost their natural links with the Yangtze River and its branches because of natural factors and human activities, causing adverse effects on the ecological environment and the sustainable economical development in the lake region. It is considered that rebuilding the link between the lakes and the rivers is very important, and 13 lakes of the Jianghan Lake Group were selected for the present study. According to statistical data about the social, economic and ecological status, these lakes were analyzed by using hierarchical cluster analysis. Based on the selected 16 impact indexes, the lakes were classified into four types and the characteristics of every type were analyzed, and the order to restoring the relation of these lakes to the Yangtze or Hanjiang Rivers was established at last.

Development and operation of hydropower projects has been a serious problem causing worldwide concern because of their impact on ecological and environmental system. China has entered into an ecologicalconstraintstage. Successful practice in some developed countries by means of establishing ecological and environmental protection standards and promoting corresponding ecological and environmental certification may have some reference significance for hydropower projects in China. In this article, the authors briefly introduced the main concepts, technical standards and operational mechanism of “Green Hydropower” in Switzerland and “Low Impact Hydropower” in USA, with a comparative analysis of the two. Based on the analysis, the authors analysed their necessity and feasibility in China in order to establish the environmental standards and certification procedures in the country. The authors further discussed the potential problems which may exist in the process of promoting hydropower environmental certification in China.