Abstract:Fluctuations of lake status reflect changes in water balance of precipitation minus evaporation (P-E) over a catchment. The ancient lake status can provide information of precipitation and humidity during the late Quaternary. Synchronous changes in regional lake status may keep lake levels from being influenced by non-climatic factors or local factors. The recognition that lake data could be used to reconstruct past regional climate changes leads to the construction of a global lake-level data base. Nowadays, Quaternary Lake status data bases have played a key role in reconstructions of continental-scale atmospheric circulation patterns and are used to compare and evaluate the simulations of precipitation and P-E from the atmospheric general circulation models. Lake records from North Eurasia show regionally-coherent patterns of changes during the late Quaternary. Lakes, peripheral to the Scandinavian ice sheets were lower than today at the glacial maximum, but high in the Mediterranean zone, reflecting the dominance of glacial anticyclonic conditions in North Europe and a southward shift of the westerlies. The influence of the glacial anticyclonic circulation attenuated in the late glacial period, and the westerlies gradually shifted northward, so that drier conditions in south of the ice sheet were confined to a progressively narrower zone in North Europe, and the Mediterranean zone became drier. During the Holocene. there was a gradual shift to conditions wetter than present in central Asia, associated with the expanded Asian monsoon, and in the Mediterranean, in response to a local, monsoon-type circulation. Conditions were drier in North Europe, reflecting the increased incidence of blocking anticyclones centred on Scandinavia. Conditions in the interior of North Euravsia were similar or slightly wetter than present, likely associated with cyclonic activity on the dowiivStream limb of the summer anticyclone in the west and monsoon penetration in the east. These reflect thechanges in insolation and glacial boundary conditions. Simulations of the response to insolation forcing at 6000 yrBP made with five different AGCMs show some common features, e. g, more humid than today in the mid-latitudes of Eurasian continent, enhancement of the Afro-Asian monsoons, drier conditions in North Europe but wetter conditions in the Mediterraneanregion. By comparing the lake data with simulated P-E fields basis can be provided forunderstanding the observed climatic changes and for evaluating the climate model simulations. Thus the paper introduced the work on European lake status database and discussed the basis, methods and applications of the data bases, in order to improve work on the Chinese data base and speed the global data base.

Abstract:The construction of global lake status data base has been introduced in this paper. This is a geological evidence-based semi-quantitative lake level data set. It consists of 6 regional lake vStatus data vsets, i. e. Oxford Lake Level Data Base, European Lake Status Data Bavse. Former Soviet Union and Mongolian Data Base, Updated African Lake Status Data Base and Chinese Lake Level Data BavSe. With uniform criteria, these sub-data-sets are incorporated into the Global Lake Status Data Base. The lake status record from the Global Lake Status Data Base essentially reflect the coherent patterns of changes in moisture condition in the spatio-temporal scale since the last glacial maximum. In the present, lakes from low and mid-latitudes are characterised by lower status whereas the lakevS in high latitudes register higher lake status. From the Last Glacier Maximum to the middle Holocene, the lakes from North America register high in cool period to low in Holocene, indicating the changes in moivSture condition from wetter to drier. The culminating dry period occurs in mid-Holocene. This change pattern of moisture condition is avSsociated with the shift of westerlies related to the presence and non-presence of ice sheet in the North America. In the Afro-Asia monsoon-al sector, the lake status are characterised by lower in the cool period and higher in warm pe-riod, particularly in the early Holocene. The higher lake status from monsoonal sector in early Holocene maintained until mid-Holocene is strongly linked with the increase in summer insolation in Northern Hemisphere. It, therefore, enhances the contrast of land-ocean thermal property, produces the strengthened monsoonal stream jet. The moisture condition changes in the mid-latitude in northern Hemisphere, including the midst of N. America and circum-Mediterranean, are related to the presence of ice sheet in the north and the displacement of the westerlies. But the lake status records in Central Asia show that the culmination of wetter condition appears in the middle Holocene rather than in the early Holocene, which indiactes that the enhanced summer monsoon started to prevail in the low-latitudinal areas in the early Holocence, then gradually expanded northward to experience in the mid-latitude in the middle Holocene.

Abstract:A 120-m-long core (33°54'N;102°33'E;altitude 3 400m) has been drilled at the center of Zoige Basin of the northeastern Tibetan Plateau. The sediment core RH reaches back to 826kaB. P. according to ¹⁴C ages and paleomaganetic stratigraghy. By analyzing environmental proxies for spore-pollen, ostrode.diatom, fosvsil pigments, hydrogen index, the δ¹³C values of organic matter and so on, the sequences of climatic evolution in this region over the past 820ka have been rebuilt. Compared organic matter δ¹³C with other proxies from the core RH.we found that the changes in δ¹³C of organic matter correspond well with that of other climatic proxies in the core RH, and can be mainly relative with the record from the deep-sea oxygen isotope, suggesting that the organic matter Sl3C in the core RH is a sensitive environmental proxy. By using maximum entropy method, in this paper, we present the revsults of the frequency rhythms recorded in the δ¹³C proxy in the sediment core RH over the past 800ka. The results showed that:(1) 0-800ka, existing quisc-periods of 80ka, 60ka, 41ka and 20ka, in which the periods of 41ka and 20ka are very close to those predicted by the Milankovitch theory. (2) 0-480ka.power spectra showed a dominant peak near lOOka and smaller peaks at the orbital periodicities of 41ka and 20ka; (3) 480-800ka B. P., discovering the dominant periods of 115ka, 33ka and 16ka, while the periods of 100ka, 41ka predicted by the Millankovitch theory vanished. All the results demonstrated that during 0-480ka B. P. the climatic changes in the region were controlled by orbital forcing, and for the past 480-800ka B. P. the periodicities had greatly regional characteristics affected by the regional constructal actions. Therefore.in this period.the climatic changes are not only influenced by orbital forcing but strongly controlled by the constructal actions.

Abstract:Closed saline lake is sensitive to the paleoclimatic change. The paleoclimatic change will bring about change of the lake level, saltness of lake water and type of ionic composition, which may be recorded in lake sediments. According to the vertical distribution of δ¹⁸O and carbonate content of Dabusu Lake, the paleoclimatic evolution of this region since 15 000 years has been recorivStructed as follows:15 400-14 000 aB. P. (depth 8.10-7.30m);the climate was cold and wet.resulting in a high lake level and stable environment. 14000-11 600 aB. P. (depth 7.30-6.00m):the climate was dry and temperate heading to rapid decline of water level. 11 600-9 500 aB. P. (depth 6.00-4.85m):the climate was cold and wet. 9 500-7 840 aB. P. (depth 4.85-3.95m):the climate became warm and dry again and the lake level was low. 7 840-6 740 aB. P. (depth 3.95-3.35m);the temperature fell and the lake level rose. The climate was cold and wet. Since 6 740 aB. P. (depth 3.35-Om):the climate became warm and dry. The lake water condensed rapidly and finally a saline lake came into being.

Abstract:A lake core, located at 100 m to the southeast of the Tianshuihai Lake (35°21'N, 79°25'E, 4 840 m asl) on the southern flank of the west Kunlun Mountains, was drilled in July of 1995. The analytical results showed that there appeared rich ostracode fossils within the depth of 56.32 m in the sediment core. A total of 10 OwStracode species from the deposits were identified. Based upon the distribution of ostracode fossils within the strata, five ostracode assemblages were distinguished as follows:1. Leucocythere sp. -Leucocythere mirabilis assemblage. This assemblage, which consisted of Leucocythere mirahilis, Leucocythere sp., Leucocythere gongheensis, Candoniella lactea and Ilyocypris bipiicata, mainly indicated a fresh water lake environment with deeper and relatively stable water. It appeared in the middle and the lower parts (depth of 44.55-44.76m, 24.65-29.33m, and 8.54-8.85m) of the core. 2. Dolerocypris fasciata-Leucocythere mirabilis assemblage. It contained Dolerocypris fasciata, Leucocythere mirabilis, Ilyocypris biplicata, Leucocythere sp. and Candona sp. This assemblage indicated a fresh water lake environment with warmer temperatures. It occurred in the sediments with the depth of 5.48-5.78 m. 3. Eucypris inflata-Cyprideis torosa assemblage. The major components were euryhaline and brackish water species, such as Eucypris inflata, Cyprideis torosa. Appearance of these os-tracodes indicated that the salinity of water is above 5‰, and the ancient Tianshuihai Lake was actually a NaCl dominated inland saline lake. This assemblage occurred in the sediments with the depth of 0-2m. 4. Limnocythere dubiosa dominated assemblage. This assmblage represented a fresh water lake or oligohaline water lake with rich HC0₃^- in water. It appeared in the sediments with the depth of 2.46-2.76m. 5. Leucocythere mirabilis dominated assemblage, This assemblage, which nearly contained the single species Leucocythere mirabilis, indicated fresh water or oligosaline water lake. It occurred in the strata with the depth of 2.22-2.46 m. Based upon the distribution of ostracode fossils and their assemblage characters, sedimentary characters, ¹⁴C and U/Th dates, the environmental evolutions of the Tianshuihai Lake area since 240 ka BP had been preliminorily recognized. The evolution of the ancient Tianshuihai Lake can be divided into six stages. Inthe former four stages (242-59 ka BP, depth of 56.32-13.61m), this area was dominated by fresh water lake. During these stages of the evolution, by the influence of climatic changes, fluvial environment occurred many times in this area. In the fifth stage (59-25 ka BP, depth of 13.61-2.76m), this area was fresh water lake with warmer water temperatures. The sixth stage (25-17 ka BP, depth of 2.76-0 m) was in the period with strong climatic changes. During the earlier stage of last glaciation period, this area was fresh water lake or oligohaline water lake, reflecting a humid climate in that time. During the last glacial maximum, this area was brackish water lake even saline lake. It can be seen that the climate turned into drought from then on, and the ancient water level dropped rapidly.

Abstract:According to the annual highest water level records by historical documents (1736-1991) about Hongze Lake, as well as the data of water level and discharge at hydrologic stations around Hongze Lake (1914-1992), this paper makes frequency analysis of various flood parameters in long and short time courses, calculates designed in-lake flood volume in return periods, and analyzes return periods and flood damage which corresponds to the flood years. The results show that;(l) Floods occured frequently in history in Hongze Lake, when serious floods took place in the years of 1786, 1851 and 1906, and water level of Zhizhuang at Gaoyan reached up to 16.3, 23.4 and 16.1 Chi respectively:(2) After Hongze reservoir built in 1953, the lake water level went up. The yearly highest water level increased by 1.22m while the perennical mean water level increaead by 1.72m; (3) The frequency analysis results on peak discharges, maximum 3-day flood discharge as well as annual mean discharge, respectively at Bengbu hydrological station in Huaihe River (1914-1992) show that the flood in 1954 wa's equivalent to 20-year. 5-year, 45.5-year and 30.0-year peak flood discharges while the flood in 1991 was equivalent to 7.1-year, 7.1-year, 10-year and 14.7-year peak flood discharges, respectively. Different frequency analysis results show that the flood discharge in 1991 was less while the damages in 1991 were greater than those in 1954.

Abstract:The present paper deals with the community of zoobenthos in the Taipinghu reservoir, Anhui Province. In quantitative samples, 26 species or genera of zoobenthos were observed during 1992-1993. Most of them are Oligochaeta and Chironomidae larvae, only one species of Mollusca was present. The standing crop exhibits a seasonal variation. The species number has decreased, but the standing crop increaseed from 0.56g/m² wet weight to 3.90g/m² as compared with the data obtained in 1985-1986, however, the index of biological diversity is relatively lower. The analyses of correlation between the parameters of zoobenthos and the environmental factors demonstrate that there is a significant positive correlation between the biomass of Oligochaeta and the total nitrogen and total phosphorus of the sediment, and a significant negative correlation between those of aquatic insects and water depth (P<0.05). Finally, the vstrategies of the raional, high-efficiency exploition of zoobenthos are also discussed for the development of fishery in the reservoir.

Abstract:On the basis of phosphorus source investigation and transportation modelling, the phosphorus balance ivS studied and the phosphorus concentration dynamics predicted. In Gehu Lake, the total input for phosphorus ivS 270t/a, and output 174.5t/a, with a deposit coefficient of 35%. The main input ways are inflow current, cage aquaculture and feeding. The main output ways are outflow current, harvest of fish and harvest of aquatic plants. The models of phosphorus transportation processes show that Gehu Lake will remain mesotrophic under the maintenance of macrophyte biomass. Otherwise the phosphorus concentration would be raised, and algea will become dominent to make the lake eutrophic.

Abstract:A comprehensive study on hydrobicxs and functions of water bodys of four lake areas with different trophic states in Donghu Lake (Wuhan) was carried out during Jan. 1991-Aug. 1993. The four lake areas differ greatly in the characteristics of aquatic organisms. The maximum values of HBC, FC, algal cell density and primary production, individual density of zooplankton and zoobenthos were found at Chagangwan area, and the minirmim values were observed at Niuchaohu area. According to all of the bio-parameters, trophic levels and states of water uses of the studied 4 lake areas, their functions are as follows. Chagangwan area is suitable for receiving and purifying waste-water; Guozhenghu area is suitable for flood control, recreations and tourist trade; Houhu area and Niuchaohu area are suitable for waterworks and tourist trade respectively.

Abstract:With the development of regional economy, Taihu Lake, which is situated in the subtropical zone of China, has been becoming a eutrophic lake. Its state of aquatic environment began to be monitored in 1991, under the support of TaiLLER (Taihu Laboratory for Lake Ecosystem Research). From the mouth of the Liangxi River to the centre of Taihu Lake, there set up 10 monitoring sites. Seventeen factors of water quality are involved in this paper. Pearson correlation and Kendall rank correlation are used to calculate the coefficients of factors and the coefficient matrixes are obtained, respectively. The minimum distance method is adopted to proceed the cluster analysis. The results show that the cluster analysis based on rank correlation coeffee-icient is reasonable while that on Pearson correlation coefficient improbable. The normal distribution test indicated that only the data of pH value and water temperature are abided by the normal distribution. It is necessary to proceed the normal distribution test before Pearson correlation is applied. Seventeen factors are classified into five groups by means of cluster analysis based on Kendall rank correlation coefficient as follows:(1) total dissolved nitrogen(TDN), total nitrogen(TN), nitrite nitrogen (NO₂-N).am-moniacal nitrogen (NH₄-N), alkalinity (OH), conductivity (CON), and chemical oxygen de-mond (COD_Mn).(2) total dissolved phosphorus (TDP), total phosphorus (TP), phosphate (PO₄^3-) and pH value. (3) suspended substance(SS) and transparency(SD). (4) dissolved oxygen(DO), water temperature(T_w) and chlorophyll a(ChL.a). (5) nitrate nitrogen(NO₃-N). Five groups reflect five respects of this aquatic environment:nitrogen pollution, phosphorus pollution, optical property, algal changes, and temporal and spatial variations of nitrogen pollutant.

Abstract:A new classification method of remote sensing image recognition, called Principal Component-Supervised Classification, is presented. Firstly, by means of principal component analysis, the component images are uncorrelated with each other and explain progressively less of the variance found in the original Landsat Thematic Mapper (TM) data in water area. After analyzing the composition of each component image and its eco-environmental implication according to spectrum features of different water types, the existing water types and their distribution features in the water area are known. Then, the training samples are selected based on the sample water types in PCA images and the classification image is produced following one of the decision rules and programs of supervised methods. This PC-Supervised method, selecting training samples based on the result image of PCA without large-area investigation on the ground or water surface, has thd advantages of unsupervised classification and a partition resolution higher than that of cluster analysis, Furthermore, its distinguishing result, applied to water quality recognition in the northern part of Taihu Lake, shows that the presented water types and their distributions are concordant with the conditions of lake body and environmental factors. So, it is indicated that PC-Supervised classification is an effective and practical method for dynamic analysis of water quality using remote sensing information.

Abstract:Based on the nature conditions of Poyang Lake district. the present situation of exploiting the water resources, the state of water contamination, and the conditions about flood and drought in this district are analyzed and, the demand of water and the tendency of water pollution in the district by 2000 and by 2010 forecasted. An overall planning is put forward for exploiting and harnessing comprehensively the water resources in the whole divStrict.

Abstract:The harnessing of Taihu Lake Basin started from 700B. C. In the historical time, people around the lake got used to more demand with less payment. The Ten Water Conservancy Projects, which were initiated in 1987, have obtained conspicuous achievements in the past yearvS. After a long-time delibration, the author reflects that some further researches and works are still needed to make the most of the Projects even after putting the Ten Water Conservancy Projects into operation. The research should go on a step further, in order to solve the problems arised in the process of the project implementation. In the long run. at least five aspects should be noted in future researches:the territorial planning on a basin scale, long-term water resources strategies, water environment control on a basin scale, water environment and regional economy, relationship between Taihu Lake and the Changjiang River, and so on.

Abstract:Waternet, cloud, snow and forest, etc have fractal features of nature. As compared with pure mathematical conception of Fractal, the fractal features in nature differs in two:1) nature fractal features will be manifest only in certain scales and ranges. 2) there does not exist such a pure conception, that it must be processed by mathematics statistical method. The fractal features of geographical phenomenon in as well as the progress in the research on seacoast, river, topography, town distribution and so on are discussed. Varigram is introduced to compute the fractal feature of Chinese lake distribution. The Chinese Lake Database, in which lakes of over 10 squared kilometres in China are included, is chosen, and the whole country group and the Qinghai-Xizang Pleteau group are selected. The distances of each two lake centres are computed, then 100 groups are divided into according to the distance. In each distance group, the average lake area variance is computed, the log-log plots are drawn. The computed slopes of recursive plot in the two groups provide information on the fractal dimensions of the two lake groups. The results show that the fractal dimension for the whole country group is 2.564 with a regression coefficient of 0.634, while the dimension for the Qinghai-Tibet Pleteau group is 2.359 with a regression coefficient of 0.759. In the end, the geographic explanation on the fractal character of Chinese lakes is given, which can be used in lake classification and lake database establishment in China.

Abstract:A method of extracting several pigments in blue-green algae of Taihu Lake including Chlorophyll, Carotenoids, Phycocyain. Oscillaxanthin and Myxoxanthophyll is introduced. The pigments are measured by UV-VIS Spectrophotometry, and the method of calculationg the pigments content in lake blue-green algae is also described. Finally, the conditions of exploitation and utilization of algae pigments in the field of food industry and cosmetics industry are discussed.