Abstract:Based on observed data of 14 meteorological stations and six main hydrological stations in lake Poyangbasin, the trends and jumps of temperature, precipitation, pan evaporation(PE), reference evapotranapiration(ETr) and discharge are analyzed from 1961 to 2003. The results indicate that the temperature jumped in 1990, then it dominated an upward trend ever since 1990. Significant positive trend was noticed after 1986 in winter. Asto precipitation, it changed abruptly in 1990. In 1992, the heavier rainstorm resulted in more precipitation in sum-mer. Significant negative trend of PE and ETr was found, especially in summer. It was found that summer ETr fellsharply after 1992. As for spatial distribution, significant climate change areas are found in the Raohe River basin,the Xinjiang River basin and the lower reaches of the Ganjiang River basin. The climate change trends above-men-tioned,that is coincident with the trend of the Yangtze River basin, are more obvious in 1990s. As a result, therunoff to the Lake Poyang also rose up. In 1990s, warm and humid climate tendency was strengthened. The climatechange of lake Poyang basin is much significant in the Yangtze River basin.

Abstract:Lake evaporations of Kangshan, Tanyin, Duchang, Xingzi and Hukou Stations in adjacent Lake Poyang are calculated individually by using instmmental reduction method and climatic model. The mean of the calculated results of the two methods calculations in 5 stations couJd be regarded as the lake evaporation in Lake Poyang. In 1955-2004, the average evaporation of Lake Poyang reached an annual 1081.2 mm and evaporative quantity of 27. 06 ×10⁸ m³. In addition, the trend of yearly and monthly evaporation were analysed, ie. a gradual decrease of evaporation in the past 50 years was noticed except for May, with an annual dropdown of 2.79 mm and a quantity of 0.05 ×10⁸ m³, which could have great impact on the utilization of water resources and aquatic environment in lake districts. Finally, possible reasons are suggested.

Abstract:The changing characteristics and tendency of runoff and sediment transport in the Poyang Lake seriously affected the sustainable development in the Lake Poyang area and the middle reach of the Yangtze River. This paper statistically analyses the runoff and sediment transport of 3 major stations in the Lake Poyang catchment. Compared with the annual runoff and sediment transport before 1990, there were some obviously changes of annual sediment transport in the term of 1990-2001. Through several non-parameter statistical methods such as the moving average, the Spearman order correlativity and the linear regression analysis, the paper concludes that during the last five decades (1955-2001), an increase of runoff at Hukou Station was noted while no obvious sediment transportation decrease was observed ;as to the Waizhou Station, the sediment transportation was decreased;in Meigang Station, the increase of runoff was small whereas the sediment transportation changed little. The rainfall variation, wa-ter-soil erosion measures, reservoir built and the evolution of land use etc. could the major factors that lead to such change. That the human activity have played a more important role, especially in the past decades.

Abstract:Under the background of global change and the rapid development of economy, the Yangtze River basin is confronted with rising pressure to prevent flood. The identification of inundation risks and the evaluation of potential flood losses are of great significance in the Yangtze river basin. This study performs the identification of the inundation risk in Honghu flood diversion area with a hydrological-hydraulic model based on raster data integrated into Arcview3.x. It processes an evaluation of the potential loss in terms of land use types and damage functions, and finally builds an dynamic database of potential loss which can serve as scientific base for the management of Honghu flood diversion area. Tlie identification of inundation risks is carried out based on a digital elevation model, calibrated with the waterstage-time curve derived from the summer flood in 1998 and manning roughness of each land use type.

Abstract:This paper has detected the trends and abrupt changes of climate changes in Lake Dongting basin in the past 40 years based on observed data of 22 meteorological stations. Lake Dongting basin had undergone a slow but steady increase of temperature since 1970s, but a significant increase with abrupt change has been detected since 1990s, especially in spring and winter;while in summer, the temeprelure has changed little. A positive and abrupt trend of precipitation in summer as well as its storm frequency has been well detected in 1990s;on the contrary, hardly has the storm density changed. The reference evapotranspiration has decreased steadily and obviously since 1960s;and in summer the decrease is of much more significance. The accelerated water circulation driven by global warming-up has brought the Lake Dongting basin more precipitation in summer, but the reference evapotranspiration has decreased at the same time,as is the main climatic contributor to the frequent floods in summer in 1990s

Abstract:I860, 1870 floods occurred during the relatively cold periods in the upper Yangtze River basin. This phenomenon is adverse to the idea that “greater occurrence possibility of floods happened to warmer periods after comparison between cold periods of 19th century and warmer periods of 20th century”. Researches on historical climatic changes during past 500 years in Yunnan, Guizhou and Sichuan, during middle and late 19th centmy and early 20th century, the upper Yangtze River basin is dominated by south-west monsoon. On the 100-year scale, 1860, 1870 floods occurred to the third cold periods during the Little Ice Age. As for the temporal and spatial distribution,the west parts of China is in relatively warm periods during the eastern ports of China is in cold periods (the relatively warm periods before the third cold periods).Relatively warmer and stronger south-west monsoon during around 19th century offered the good climatic background for these two flood events.

Abstract:According to the water-balance analysis carried out in Lake Bos ten, discharge of Kaidu River tributary accounts for 85% of the lakes inflow, and thus plays a crucial role in the fluctuation of its water-level. Glaciers, as an important component of the water resources in the upper reach of Kaidu River valley, has had a considerable effect upon by the global and regional climate change of recent years. Water melted away from glaciers has channeled into the downstream section of the river and exceeds the base flow to have entered the Kaidu River over the past twenty years, during which time the lake keep a high inflow level. Small-sized glaciers are more sensitive to temperature rising. With the gradual diminishing and eventual disappearance of these small and middle scale glaciers situated in a fairly low-altitude location, the ELA (snow-line) will rise and the icecap will become thin. Hie volume and distribution area of the glacier will decrease, which will make the glacier less sensitive to climate change (in other words, preventing the glacier from melting to such a degree), and bring less glacier-melt water discharge. As a result, the water-supply from melting glaciers that will flow into Lake Bosten will lessen.

Abstract:The study focused on the water quantity exchanges between the typical river network area (at Dapu Town, Yixing City) and the western Lake Taihu. Effect of rainfall taken into consideration, the runoff formation and flow concentration model considering various underlying surfaces was adopted to simulate the runoff process, both of the typical river network area and the nearby western hill area(2002 (base year), 1998 (wet year), 1995 (normal year) and 1994(dry year) respectively). Then the non-steady stale river network water quantity model was established by adapting to the typical river network area. Combined with the results of the runoff formation and flow concentration simulation, the water quantity model was applied to simulate the dynamic changes of water flow in the typical river network area, for each year mentioned respectively. Finally, water quantity exchanges between the typical river network area and the western Lake Taihu was ascertained. Changes of the water quantity exchanges in the year and between the years was also studied, on both co-current and adverse current conditions.

Abstract:Surface water was taken from the east shore of the mouth of Meiliang Bay, Lake Taihu. The lake water was sampled under weak (2 m/s), modest (7 m/s) and strong wind-wave (11 ra/s), respectively. Suspended solids (SS) were obtained by centrifuging 25L surface water. SS were further freeze-dried and microwave digested, and the contents of Co, Cr, Cu, Ni, Pb, Zn, Al, Ca, Fe, Mn in SS were determined by ICP-AES. It was found that the particulate metal amounts increased gradually with wind speed. Moreover, different metal contents in SS showed different variation trend with wind speed. The contents of Zn in SS decreased with wind speed ;the contents of Mn and Cu were highest at middle wind speed;and contents of Al, Fe, Ni, Pb, Co, Cr were lowest at the middle wind speed. These results suggested the metal contents in the shallow lake water were mainly influenced by wind-wave disturbance.

Abstract:The wet and dry particle depositions, particle and gaseous phase PAHs in atmosphere, and dissolved phas? PAHs in water were sampled by passive sampler, high-volume air sampler and semipeameiable membrane device (SPMD) in Lake Luhu, respectively. According to the stagnant two-film model and Henry theory, the direction and magnitude of fluxes of PAHs across the air-water interface in Luhu Lake were calculated based on the analytical data. The result showed that the atmosphere deposited about 1300 g of PAHs to water and water volatilized about 220 g of PAHs to atmosphere. PAHs with different molecular weights have different predominant processes across the lake water-air interface

Abstract:The water environmental capacity of phosphorus and nitrogen is an important factor to control water eutrophication in lakes/reservoirs. The quantitative connection between the growth of predominant species i. e. uniol-gat strain of Microcystis aeruginosa and the concentration of TP and TN in Lake Songhua was studied in the laboratory using simulation method. Results indicated that TP threshold is 0.065 mg/L, TN threshold is 0.843 mg/L in the Lake Songhua. Risk assessment theory and Monte Carlo method were employed to analyze the concentration distribution regulation of TP and TN in the lake based on the data from 2002 to 2004. The paper developed an uncertainty method to calculate water environmental capacity of TP and TN in lakes/reservoirs. Because the uncertainty method was based on water self-purification law, and it isn * t needed to calculate some parameters difficult to identify, such as the degradation coefficient of the pollutants. It is useful to calculate the water environmental capacity of TP and TN in the Lake Songhua with the uncertainty methods. The result indicated that the maximum permissible discharge amounts of TP and TN in the Lake Songhua watershed were 2123. 78 t/a and 7018. 82 t/a. In order to control that eutrophication probability in the Lake Songhua was below 0.001, amounts of TP and TN were need to decrease 3208.34 t/a and 18648.91 t/a, respectively.

Abstract:Lake Dongting, which is the second biggest fresh water lake in our country, is located in the middle reaches of the Yangtze River. For a long time, the Yangtze River and the other four riverways which inpour in Lake Dongting always take a great deal of sands every year, as a result, the lake was filled up, many continents were developed,the water velocity was slowed and the water environmental quality was worsened. In order to resolve these problems, dredging engineering is actualizing in Lake Dongting now. Combined with the engineering, the changes in C0D_Mn capacity, TN capacity and TP capacity of Lake Dongting before and after dredging were simulated based on the analysis of the Lake Dongting actuality water environmental quality in the paper, and the reasons were also analyzed. It was found that dredging engineering enhanced the water environmental capacity of Lake Dongting. Especially in the lower water and higher flux, the water environmental capacity increased more. Under the same source of explicit pollution, the dredging was helpful for improving the water quality of Lake Dongting, and it could ameliorate the eutrophic state of Lake Dongting in a certain extent.

Abstract:Effect with growing of submerged macrophytes on NH₄⁺-N and PO₄^3--P concentration in the interstitial water was studied by using undisturbed core samples in Lake Taihu,and analyzed the relationship between biomasses of submerged macrophytes and amount of nitrogen and phosphorus release. The results showed that concentration of NH₄⁺-N from 0-5 cm in interstitial water was gradually reduced by the biomasses increase of submerged macrophytes,and amount of nitrogen release is distinctly negative correlated with biomasses of submerged macrophytes;The PO₄^3--P concentration in interstitial water change was me peak tendency by the growing of submerged macrophytes,indicating that there was no distinct corlationships between amount of phosphorus release and biomasses of submerged macrophytes. There mingt exisf different biogeochemcal mechanism of the absorption of nitrogen and phosphorus by submerged macrophytes

Abstract:In allusion to the algal eutrophlcation problem of urban shallow lakes, four enclosures were set up in an urban eutrophic pond of Nanjing City to restore submerged macrophytes communities. Results showed that Eichhor-nia crassipes can be used to improve the transparency of water body, and its effect was relative to its coverage when its coverage was less than 0.3m. With the coverage no less than 0. 3 Eichhomia crassipes can make transparency improved from lower than 0.3m to higher than 0.6m during 30 to 40 days in summer. The submerged vegetation was availably restored after transparency improved to higher than 0.6m. Compared to the period without submerged vegetation,the transparency of the water body was enhanced 70% and Chi.a concentration were reduced 50% correspondingly.

Abstract:Four experiments were conducted in laboratory for hydrostatic settling behavior of suspended matter in Lake Taihu in April and May, 2005. The settling velocity of suspended matter was calculated by both Stokes equation and McLaughlin method, and the results were further compared. The results showed that settlement of suspended matter in Lake Taihu was flocculation settlement. It also showed that the suspended matter concentration decayed exponentially with time, which was more obvious when the percentage of inorganic suspended matter accounting for total suspended matter was higher (R²≥0.99). When the suspended matter concentration was low, no clear relationship was found between settling velocity and suspended matter concentration. But settling velocity obviously rose with the increase of suspended matter concentration while the latter was high. Based on the data of four hydrostatic experiments, it was found that settling velocity (ω) of suspended matter and suspended matter concentration (C) fitted in Logistic Curve ω= 0.021/(1 + exp(-0.026(C-166. 3)),R² = 0.98, n= 54. Comparing two calculation methods, Stokes equation could be used to estimate the settling velocity, but the calculation result was more accurate using Mclaughlin method. The settling velocity of suspended matter estimated in Lake Taihu ranged from 0.002 cm/s to 0.005 cm/s.

Abstract:Based on the ecological survey, the ecological indexes of microorganisms, physico-chemicals and chlorophyll-a was measured on the water source area of the middle-line project of Transferring Water from South to North, 2005. The result showed that the nutrition type of the water source could be regarded as mesotrophyic;Danjiangkou Reservior is suitable for water source because the indexes except TN belong to the standards of Grade I water. This study would provide scientific information for data bank of long-term ecological research on middle-line project and policy of ecological environmental protection

Abstract:Based on two methods of Sieving and Pollen-slide, the author designed different size method of charcoal analysis to extract and count different fragment charcoal from loess'paleosol and culture layer. Sieving method is used to extract big fragment of charcoal (the size is over 125 ?) as the proxy of local fire regime;while Pollen-slide method can be used to get small fragment of charcoal (the size is lower 125 ?) as the proxy of regional fire regime. The different size method of charcoal improves the precision of the charcoal analysis and enriches the con-tenl on the study of fire history. The method provides a good way to reconstruct the fire variation and an important approach to study the vegetation history and ecological characteristic on the Loess plateau. Furthermore, the method can make great sense to understand the climatic variation and discuss human activity and their impaction to environ-ment

Abstract:The matter element analysis has been used to optimize points selection of water quality monitoring in the Lekn River basin of Lake Poyang, taking the average monitoring data in 8 years which is from 1995 to 2002 as the original data. Matter element matrix of standard and partial unit can be established on condition that optimum and second optimum points are chosen, connected with integrative and correlative function, the optimized points are chosen. Meanwhile, the distances methpd which is belonged to the correlation and the Means Cluster process are used to the classification of monitoring points. Integrating three methods above, the 13 traditional monitoring points in the Le, an River basin of Lake Poyang can be optimized to 9 monitoring sites.

Abstract:Hot-ethanol extraction method is a widely used method in the world to determine phytoplankton chloro-phyll-a concentration. This paper aims lo introduce the hot-ethanol extraction method in detail to all the scientists dealing with aquatic environment research in China. By experience from the authors, possible error during the operation of the analysis was discussed.

Abstract:The biodiversity of fish in the Yangtze River valley is of great value for the ecology, economy and scientific research as it is characterized with a great variety, abound resources, high peculiarities and various economic species. But its population tends to go down obviously due to so many threatening factors like the fish-migrating barrier, habitat deterioration and water regime change as a result of the river cascade exploitation,i. e. hydraulic works. In order to protect the biodiversity of fish, it is quiet necessary to upgrade the engineering concept and technology for the planning and design of hydraulic works, and build up necessary fish passage facilities like fishway for the reservoir ecology operation, and also essential to create the natural fish reserve and establish an ecological compensation mechanism etc.