Abstract:Changes of rainfall and temperature caused by climate changes have a great impact on water resource and runoff in watershed.Channel-type reservoir,due to its characteristics of river and lake,is affected intricately by climate.As a case study of Changtan Reservoir in Meizhou City,Guangdong Province,coupled watershed hydrological model SWAT and Environmental Fluid Dynamic Code (EFDC) have been used to study the responses of hydrodynamics (characterization by water age) to climate condition in the channel-type reservoir.According to frequency analysis of 58 years rainfall data from 1952 to 2010 in Meizhou City,selected rainfall guarantee rates are 20% (wet year),50% (average year) and 90% (dry year) as three climate schemes.Tributaries of Changtan Reservoir were simulated with the rainfall and temperature in the typical years as input conditions for SWAT mod-el,and hydrodynamics process was simulated with the inflow of the tributaries as boundary conditions.The results showed that, water age increased exponentially along Changtan Reservoir,and was greatly affected by climate conditions.Compared to wet year, in average year and dry year,annual rainfall reduced 14% and 49%,and inflow reduced 23% and 62%,and water age increased 66% and 247% near the outlet dam,and up to 81% and 290% in tributaries,respectively.So,climate conditions had a great effect on the reservoir's hydrodynamics,especially in the vicinity of tributaries.Changtan Reservoir exhibited the characteristics of river and lake under different climatic conditions.Near the dam,it exhibited the characteristics of river in wet year,and the characteristics of lake in average and dry year gradually.Additionally,coupling of watershed hydrological model SWAT and EFDC,it is an effective method for making up the needed long series of high frequency measured data and improving the accuracy of hydrodynamic model simulation in lake and reservoir.

Abstract:River-lake system interconnection demand is one of the key elements among the research of river-lake system interconnection strategy.It reflects the demand of the social-economic development on water diversion,flood regulation,eco-environment improvement and the maintenance of the health of river-lake system.It is based on the inherent ecological properties that a drainage system can provide various water ecosystem services to a river-lake system.Since the river system,river system interconnection demand, the water ecosystem services,and river system interconnection engineering are closely interconnected,the methods which have been adequately studied for assessing the water ecosystem services can be applied to the assessment of river system interconnection demand.So methodologies for evaluation of river system interconnection demand are established by applying the water equivalent method.With a long historical practices of river system interconnection in Lake Taihu watershed,which is a typical and emergent floodplain river network area in eastern China,demanding on Lake Taihu river system interconnection is assessed in this study.The main demand includes water resource diversion,flood regulation,water purification,and habitat sustainment.Purification water demand per year of retained pollutants in the lake is 2.85×10¹⁰ m³/a,ranked the first place.Water resource diversion demand is 3.0×10⁹-4.2×10⁹ m³/a,ranked the second place,while the demand of flood regulation of the lake is decreased by 7.2×10⁸-10.7×10⁸ m³/a.Purification demand of the water from the lake is 8.14×10⁹ m³,and is consumed once only;the habitat maintenance water demand is 3.58×10⁹ m³.The results show that water environment improvement demand is tremendous.To ease the stress,countermeasures such as control of the pollutant entering into the lake,desilting and dredging the lake,and ecological restoration of the lake water need to be applied firstly,then the diversion of clean water as an assisting way.There are different corresponding interconnection ways for each demand,and it is necessary to confirm the ratio of each interconnection project.

Abstract:The eastern Lake Dongting wetland is of great importance worldwide.It has been suffered from progressive degradation lately.Wetland ecosystem is considered to be adapted to hydrological sequence before alteration caused by climate changes and human related activities.Average monthly water-level of three hydrological stations in the Lake Dongting region were analyzed in this study to obtain ecological water-level.The point of the highest T statistic value calculated by moving T-test method was considered to be the alteration point.The sequence was then divided into two parts.The subsequence before alteration point was used to find the most fitted probability distribution function.The ecological water-level was considered to be the average monthly water-level of the highest probability of the probability distribution function.The results indicate that average monthly water-level has been alternated, and the ecological water-level determined in this paper is reasonable and can provide some guides to the restoration of the Lake Dongting wetland.

Abstract:The effect of urbanization on the stream structure and connectivity has been a hot topic nowadays.At the present,fast urbanization has caused many enviromental problems,such as the decreasing of river numbers,rivers unconnected,water quality worsening,and frequent flood.The Qinhuai River watershed,mainly located in Nanjing City,Jiangsu Province,China,could serve as a good example.Two remote sensing images in 1979 and 2006 in mid-lower reaches of the Qinhuai River were processed and classified for the analyses on the spatial and temporal characteristics of underlying lands,which were the result of urbanization.The river systems were extracted based on the topographic maps in 1980s and 2009,and the influence on the stream structure and connectivity was discussed using a combination of stream grading and structure analysis methods on the river corridor in landscape ecology.Results show that: (1) Urban land has increased 9 times by 84.54 km²,and a large area of forest land has been transformed into urban land.Besides,paddy and dry land area were also decreased.Expanding of the urban areas of the city has invaded many other lands.(2) Length of the river has been decreased by 41% and the main river channel of the catchment are broadening.The stability of river has been declining and composition of the river system network was getting simpler.The stream stucture was developing from a complex model to a simple one.(3) Parameters of the river connectivity were both decreased.This explains why the rivers were not as well connected as 30 years ago and flood risk of this area current is high.

Abstract:The modified local-soil-induced ecological restoration (MLS-IER) technology was tested to alleviate the organoleptic problem and water quality deterioration originated from the "black spots".The lab study showed that chitosan modified local soil was more effective than PAC in the mitigation of black substances in the water of the black spots,the turbidity was reduced from > 2000 NTU in the control to 5 NTU at the dosage of 55 mg/L MLS,and the capping with soil or sand reduced the resuspension flock of black spots.The field pilot study showed that 30 min after the treatment with MLS-IER,the level of nutrients (TN,TP) decreased by 97%,odor compounds of MIB and DMTS decreased by > 75%,DO of the surface and bottom water increased by 75% and 183.5%,respectively.MLS technology provides an in-situ strategy to alleviate the negative effect of black spots.

Abstract:In view of the status of serious pollution in Lake Taihu basin,it is necessary to establish an appropriate water quality criteria to protect and restore the lake environment.According to the data on total phosphorus,total alkalinity,mean water depth in 12 reservoirs and lakes with little human influence in Lake Taihu basin as well as the early-time (pre-industrial) data in Lake Taihu,a morpho edaphic index (MEI) model was built.The correlations between TP and two factors,which are mean water depth and total alkalinity in MEI model,were analyzed,respectively.Considering the fact that all the lakes in Lake Taihu basin are shallow, the improved MEI model was proposed.Then the improved MEI model was used to determine TP reference concentration in Lake Taihu.The result showed that the reference concentration of TP was 0.025 mg/L.This study is aimed at diversifying the methods of nutrient criteria research in China,and providing theoretic support for eutrophication control in Lake Taihu basin as well as establishing nutrient criteria for similar lakes in the middle and lower reaches of the Yangtze River.s

Abstract:In this study,the efficiencies of a pre-dam complex system for non-point source pollution control was investigated for the management of the Tangma Reservoir in Liyang City,Jiangsu Province.The pre-dam complex is composed of settling area (A), shallow-water area (B),deep-water area 1 (C),deep-water area 2 (D),surface flow wetland (E),and biological membrane purification area (F).The results showed that the pre-dam complex system under the study contributed to significant improvement in the quality of agricultural non-point source pollution flowing through the pre-dam.The removal of TN,TP,COD_Cr could be up to 67.2%,68.2% and 89.3%,respectively,when the retention time was 1 d.The removal efficiency was increased with increasing of retention time,while the increment was small and stable.Moreover,increased areas (E and F) could significantly improve the removals of SS,TN,TP and COD_Cr,particularly the smaller SS which was consisted of size less than 15 μm.Furthermore, based on laboratory results,it was suggested that the retention time be 2-3 d in the Tangma project,and the system be optimized to improve the purification efficiency and high utilization of the area.

Abstract:To explore the role of periphyton in nutrient cycle in eutrophic shallow lake,the effect of the periphyton attached on Potamogeton crispus on nitrogen and phosphorus loads was examined in a mesocosm experiment conducted in controlled greenhouse.A gradient of ten nutrient concentrations (nitrogen concentrations from 3 to 12 mg/L and phosphorus concentrations from 0.1 to 1.0 mg/L) was established with NH₄Cl,NaNO₃,KH₂PO₄.The results showed that: The content of periphyton chlorophyll-a (Chl.a),organic matter,inorganic matter and total periphyton increased significantly with nitrogen and phosphorus loads increase.The content of periphyton Chl.a,organic matter,inorganic matter and total periphyton reached peak at T10 (TN 12 mg/L, TP 1.0 mg/L) with Chl.a 2.005-4.765 mg/g(DW) periphyton,organic matter 29.027-94.886 mg/g(DW) Potamogeton crispus, inorganic matter 176.881-397.750 mg/g(DW) Potamogeton crispus,and total periphyton 205.909-492.636 mg/g(DW) Potamogeton crispus,respectively.Periphyton Chl.a,organic matter,inorganic matter and total periphyton generally increased with time.Differences in periphyton Chl.a,organic matter,inorganic matter and total periphyton were significant among growth periods, and showed rapid growth period > stable period > decline period.Moreover,this trend occurred at all nutrient concentrations.The periphyton Chl.a,organic matter,inorganic matter and total periphyton of decline period were 1.046-1.826,1.046-1.638,1.029-1.858 and 1.106-1.717 times those of stable period,and were 2.324-4.059,2.323-3.640,2.101-3.792 and 2.280-3.584 times those of rapid growth period.The results above indicated that the periphyton of Potamogeton crispus and its decline were enhanced by elevated nitrogen and phosphorus loads.

Abstract:In order to understand eutrophication and its relationships with environmental factors in gate-controlled river network system of Chongming Island,variations of environmental factors and algae as well as their interaction mechanisms were studied based on seasonal water quality data of the river network.Results indicated that the concentrations of nutrients in the river network were high and nitrogen pollution was particularly serious.The contents of nutrients,Chl.a and trophic state increased significantly after the Yangtze River water entered into the river network.The proportion of diatom decreased with increasing proportions of cyanobacteria and chlorophyta in the river network comparing with the water of the Yangtze River.Although water temperature,pH,turbidity, TN,TP,NO₃^--N and DOC had significant correlations with algal biomass,the relationships between algal community and environmental factors were different.Water temperature and TP were the main factors of promoting growth of cyanobacteria;chlorophyta was closely related to TN and NO₃^--N;and diatom was only related to the turbidity while nutrients were not promoting factors of diatom.

Abstract:Previous study indicated that wheat bran leachate(WBL) exhibited strong inhibitory effect against Microcystis aeruginosa.In order to elucidate the responses of M.aeruginosa photosystem to the stress of WBL,pigments and chlorophyll fluorescence transient of M.aeruginosa CHAB-109 under the stress of WBL were analyzed.The results indicated that intracellular pigment contents decreased when WBL was of 1.6 and 3.2 g/L.Results of chlorophyll fluorescence transient analysis indicated that the absorbed energy(ABS/RC),the trapped energy for reduce of Q_A (TR₀/RC),the trapped energy for electron transport(ET₀/RC) were all inhibited by WBL.Energy flux ratio analysis of PSⅡ indicated that no damage induced by WBL at the electrons providing side of reaction centre of PSⅡ,but it can damage the acceptor side of reaction centre.Combining the results of energy fluxes and flux ratios indicated that the electron transport chain from reaction centre to Q_A and far beyond Q_A are the damage sits of WBL on Microcystis aeruginosa.

Abstract:A survey on phytoplankton was carried out along the main stream of the Yangtze River and inundated and backwater areas of 26 tributaries in April,2010.Species of diatoms,green algae and cyanobacteria accounted for 93.33%-93.88% of the total phytoplankton.Dominant species in the main stream,inundated area,and backwater area were 1 species in 1 phylum,six species in 3 phyla and 6 species in 5 phyla,respectively.The occurrence rates of dominant species in the main stream,inundated area, and backwater area were 15.38%,9.23% and 25.00%,respectively.The average value of phytoplankton standing stock was the highest in backwater area,followed by inundated area and the lowest in the main stream.Compositions of phytoplankton standing stock were different among the main stream,inundated area and backwater area.The proportions of green algae and diatom were the highest in the main stream and inundated area,while the proportions of cryptophyta,cyanophyta and pyrrophyta were all the highest in backwater area.Shannon-Wiener diversity indexes and Pielou evenness indexes were the highest in inundated area,followed by the main stream,and the lowest in backwater area.Shannon-Wiener diversity indexes of backwater area of 17 tributaries and Pielou evenness of backwater area of 8 tributaries were both lower than those inundated area.Water quality assessment indicated that the proportions of slightly polluted or not polluted monitoring sections in the main stream,inundated area and backwater area were 76.92%,84.62% and 47.06%,respectively.Moderate polluted or seriously polluted were found in backwater area of 19 tributaries (73.08%) and inundated area of 7 tributaries (26.92%).The influence of the Three Gorges Dam Project on phytoplankton and water quality in backwater area is greater than that in the main stream of Yangtze River.

Abstract:The diurnal migration of Microcystis was studied using a cylindrical reactor to demonstrate how colony morphology affects the tendency of Microcystis cells to float or sink.Experiments were carried out using single cells and colonies from laboratory incubation and also colonies from Lake Taihu.Results showed that single cells had significant diurnal migration while this was apparently insignificant in colonies either from laboratory incubation or natural water.In contrast,colonies taken from Lake Taihu exhibited remarkable floating features.These were observed to be due to differences in specific gravity between cells from laboratory incubation and Lake Taihu.In addition,colony morphology affects significantly the upward movement of the cells.

Abstract:In order to study the effects of plants' roots oxygen release on the nitrification and de-nitrification in man-made wetlands, we selected two operation modes,namely traditional continuous operation mode and new operation mode (a continuous feeding during the day and stop feeding during the night).The experiment was carried out in a small integrated vertical-flow man-made wetland system with a hydraulic loading rate of 0.71 m³/(m²·d),and the representative emergent plant cattail as the wetland plant was chosen.The results showed that the aerobic nitrification took place mainly during the day and the anaerobic-anoxic de-nitrification, during the night,in the system.In addition,the daytime nitrite accumulation was 5 times and nitrate accumulation was 2 times in new operation mode comparing to those in traditional mode,the decrements of nitrite and nitrate were 64% and 26% bigger, respectively,than in traditional mode.The new operation mode showed a better nitrogen removal effect.

Abstract:In order to understand the effects of the ingestion of metazooplankton on the formation of Microcystis blooms in summer in Lake Taihu,a field simulation experiment had been carried out by taking water samples from the Meiliang Bay in Lake Taihu from July 15 to August 14,2009.During the period,visible Microcystis blooms floating on the water surface were found in the controls which did not filter out metazooplankton,but Microcystis blooms were not found in the treatments which had filtered out metazooplankton.Nine species of metazooplankton were found in the controls and three species of metazooplankton in the treatments during the whole experiment.Metazooplankton were found in the treatments in the sixth days of the experiment.The zooplankton biodiversity (H) analysis showed that the value of H in the controls was significantly higher than that in the treatments.During the later stage of experiment (21-30 days),the average density of Microcystis spp.in the controls was significantly higher than those in the treatments.During the experiment,the density of Microcystis wesenbergii and Microcystis flos-aquae in the controls were significantly higher than those in the treatments,and Microcystis wesenbergii contributed 60.79% of the total Microcystis abundance in the controls.The results showed that the ingestion of metazooplankton could not control the Microcystis blooms,on the contrary,metazoop-lankton,especially large metazooplankton,promoted the formation of Microcystis blooms.The experiment also suggested that the community structure of metazooplankton was an important factor in affecting the formation of Microcystis blooms.

Abstract:The tracking study of raising crabs during production period in the reclamation areas of Lake Gucheng was carried out in order to find out the economical benefits and pollution influx of different management modes.The results demonstrated that the crab eco-culture in the reclamation areas had a positive effect on the economical benefits.The profits,which could be affected by differences in the aquaculture management,ranged from ￥24000 to ￥105000 Yuan RMB per hectare.The major input was feed, which took up 41.6% of the total input of ￥63000 Yuan RMB per hectare.The total output was ￥103000 Yuan RMB per hectare.The concentrations of nitrogen (N) and phosphorus (P) varied significantly among different ponds,with a total N load of 268.5 kg/ha and total P load of 64.5 kg/ha.Feed made a major contributions in the input of N and P,70% and 90%,respectively;culture products and outflows only took a small amount of N and P loads,and harvesting aquatic plants was the main method to remove N (86%) and P (88%).Consequently,the key to improve the economic benefit,reduce pollution outputs and protect water environment of Lake Gucheng was to optimize the feedstuff structure,perfect the feeding system and strengthen the harvesting of aquatic plants for more effective pollutant transformation.

Abstract:Alternanthera philoxeroides callus,cultured by tissue culture technique,was exposed to gradient concentration of Zn²⁺ (0,0.2,0.4,0.8,1.6 mmol/L) for 7 d.Oxidative stress and changes in polyamines metabolism caused by excessive zinc were investigated.Results showed that,with the increasing of Zn²⁺ concentration: (1) the rate of O₂^-· generation and thiobarbituric acid reacting substances content was enhanced remarkably,and the superoxide dismutase activity and the chlorophyll-a content were decreased singnificantly;(2) the activities of arginine decarboxylase and ornithine decarboxylase were increased gradually, while the activities of polyamine oxidases and diamine oxidases were increased at first and then decreased at higher concentrations;(3) the contents of total-putrescine and total-spermine was decreased at first and then increased,and the contents of total-spermidine only showed an remarkable increase at 1.6 mmol/L Zn²⁺ treatment;(4) the free-putrescine content changed in a similar pattern as its total counterpart,the free-spermidine content showed a decline at 0.8 mmol/L and 1.6 mmol/L Zn²⁺ treatment,the free-spermine content had little fluctuation except a decrease at 0.2 mmol/L Zn²⁺;(5) the contents of perchloric acid soluble conjugated (PS-conjugated) putrescine and spermine declined at 0.2 mmol/L Zn²⁺ treatment and then increased,the PS-conjugated spermine content continued to rise;and (6) the contents of perchloric acid insoluble bound (PIS-bound) putrescine and spermine were descended gradually.The data presented here showed that excessive Zn²⁺ treatment can cause evident oxidative stress and alter the polyamines metabolism balance.The conversion from PIS-bound polyamines to PS-conjugated polyamines was one of the key characters of polyamines metabolism alternation in A.philoxeroides callus under excessive Zn²⁺ treatment.The accumulation in the total polyamines characterized by the PS-conjugated polyamines played an important role in A.philoxeroides cal-lus in response to excessive Zn²⁺ treatment.

Abstract:The losses caused by flood disasters are becoming increasingly serious with the rapid development of social economy.As an important non-engineering flood protection measure,real-time flood forecasting plays an important role in flood control.Due to the severity of flood disasters and the complexity of flood routing process in the Huaihe River basin,the research on flood forecasting system has been a focus for a long period.A case study from Wangjiaba to Xiaoliuxiang section is discussed and a research on flood forecasting system is presented in this paper.On the basis of the hydrologic characteristics in the study area,this paper takes flood flow routing as mainline,uses the Xin'anjiang model for runoff yield prediction,generalizes flood diversion and retarding regions, applies hydrologic and hydraulic methods to simulate flow routing in the main channels,and fits stage-discharge relationships by multiple regression method.A general system is established by integrating the above parts and then by coupling K-Nearest Neighbor method to attach real-time correction to forecasting results for the real-time forecasting system.Inspected in 2003 and 2007,the system achieved high prediction accuracy,which proves that the system is sound and can be applied to this basin.

Abstract:Evapotranspiration (ET) from the land surface is a crucial component of water and energy balance.In the hydrologic balance,evapotranspiration determines the amount of precipitation resulting in runoff.To understand the process of water balance in the Lake Poyang region,it is necessary to clarify the temporal variation of ET and response of impact factors.In this study, based on MODIS products data,the ET over the Lake Poyang region was estimated using surface temperature-vegetation index triangle method during 2000-2009.The results showed that the annual average ET was 797 mm during 2000-2009,ranging from 685 to 921 mm,the highest ET occurred in 2004.The annual ET of water body was 1107 mm,which was higher than that of land surface over the Lake Poyang region.The ET was a dominant component in water balance,and the percentage of annual ET to precipitation was 55% on average for land surface of the Lake Poyang region.The ET of the Lake Poyang region was mainly affected by radiation and air temperature,monthly ET and air temperature showed significant exponential relationship,the ET in 2007 was more sensitive to air temperature than those in other years.The ET departure indicated significantly negative to precipitation departure in 2007,and there was no obviously relationship in other years.The ET of Lake Poyang wetland showed positive to water surface area, however,when water surface area was less than 30% in severe hydrological drought year,the ET was deceasing with water surface area increased.

Abstract:A novel index,Normalized Difference Chlorophyll Index (NDCI),is introduced in this study to estimate the chlorophyll-a (Chl.a) concentration from Hyperspectral Hyperion data,HSI data,and measured Chl.a concentration data for Lake Taihu and Lake Chaohu in eastern China.The best bands were selected by analyzing spectral channels of the Hyperspectral data and the spectral characteristics of the water.The Chl.a concentration was estimated by considering the regression relationships between NDCI and the measured Chl.a concentrations through the analysis of the NDCI reflection factor and points data of measured samples.Comparing the results of the NDCI method to that of the normal ratio,first-order differential,and three bands methods, the NDCI method has performed better in simplicity,accuracy and applicability than the other three methods in the estimation of Chl.a concentration in case Ⅱ waters.

Abstract:Through field investigation in the upper reaches of the Hanjiang River,palaeoflood slackwater deposits were found in the Ankang east section.The results of sedimentary analyses indicate that these slackwater deposits are typical suspended sediment load deposits of floodwater.By stratigraphic correlation,OSL dating and archaeological dating,the palaeoflood events represented by SWD1 were dated to be between the palaeo-climatic stage of BL+AL and Younger Dryas Event (YD,12500 a B.P.).During this period,the upper reaches of the Hanjiang River experienced a series of rainstorm flood events.The pollen records from the Southern Lake of Shennongjia area in the upper reaches of the Hanjiang River also suggest that this was the period of high climatic fluctuation frequency.The SWD2 in the east Ankang section appears in the bottom of well-developed modern topsoil layer.At the edges of Ankang-Yunxian river terrace,the set of SWD layers often cover the culture layer which belongs the Northern Song Dynasty when climate condition was very unstable,and serious drought and flood disaster occurred based upon historical records.The palaeoflood events recorded by SWD2 were dated to be AD 1000-1100 (i.e.1000-1100 a).Based on the reconstruction of palaeoflood peak stages and the hydrological parameters for the river section,the palaeoflood peak discharges were between 35970 and 47400 m³/s.These values were checked with the the reconstruction of the flood in 2010 based on the stage indicator identified during the fieldwork,and the results showed the Ankang hydrologic station measured data error is only 4.52%.Thus we believe that the peak flow calculation for the upper reaches of the Hanjiang River canyon ancient flood is reasonably accurate,the calculation results are reliable.Based on our calculation from sedimentological perspective the historical flood investigation results were combined with observed flood series,with a large value of the complete sequence of frequency calculation method,and the upper reaches of Hanjiang River in the eastern part of Ankang section million-years-scale peak flow and frequency relations were established.The results provide data for establishing flood discharge-frequency relationship at a 10000-year time-scale in the upper reaches of the Hanjiang River.This is very critic and will provides key data for hydraulic engineering and flood control in the upper reaches of the Hanjiang River and the flood control and disaster mitigation engineering construction along the waterfront towns in the region,except the scientific value of the Hanjiang River's regional changes in climate and hydrology in response to the global climate changes.