Dianchi Lake Basin Research Articles

Research of level Ⅰ and Ⅱ aquatic ecological function regionalization in Lake Dianchi basin

The aquatic ecological function regionalization is the basic requirement of water resources management,water environment protection and water ecology restoration. Especially for lake basins which are connected closely with human activities and filled with inconsistencies,the aquatic ecological function regionalization is an indispensable condition of realizing sustainable development in the watershed. So how to delineate reasonable ecological function regionalization becomes the major issue to be addressed in the integrated watershed management. In the case of Lake Dianchi basin,the dominant water ecological functions are first determined according to the current problems of water ecosystems. And in the premise of hydrological integrity,sub-catchment units are divided for the first and the second level regionalization respectively. Then we indentify the key factors that affect water ecological function significantly and construct the index system for the watershed based on the relative theories,including ecosystem service function,scale effect and rule of territorial differentiation. The overlaying and clustering methods are used for multiple indices. Then final boundary is adjusted slightly according to water quantity and quality distribution. The consequence shows that Lake Dianchi basin is divided into 5 level Ⅰecological function regions and 10 level Ⅱecological function regions. By using the density of periphytic algae and Limnodrilus,assessment is made on the reasonability of regionalization. Finally the problems remained in the water ecological function regionalization are discussed.

Responses of phytoplankton functional groups to simulated winter warming

We investigated the seasonal dynamics of phytoplankton functional groups and the relevant environmental factors (water temperature, total nitrogen content, total phosphorous content and water transparency) in Dianchi Lake, China. We also examined the growth rates and physiological characteristics of representative species in laboratory cultures. In the field experiment, five dominant functional groups, including M (mainly consisted of Microcystis aeruginosa; Microcystis wesenbergii and Microcystis flos-aquae), H1(mainly consisted of Aphanizomenon flos-aquae), J (mainly consisted of Scenedesmus; Pediastrum and Coelastrum), F (mainly consisted of Oocystis and Kirchneriella) and P (mainly consisted of Melosira), were determined. Groups M and J were prevalent throughout the year and comprised more than 90% of the total biomass. Group M was prevalent at a relatively high temperature in summer and autumn; by contrast, group J was dominant at low temperature in winter and early spring. Co-cultivation laboratory experiments revealed that the biomass and the density of Microcystis sp., which is the representative species of the functional group M, were higher at 18 degrees C than at 13 degrees C. Conversely, the density and the biomass of the representative species of the functional group J (consisted of Pediastrum duplex, Coelastrum microporum and Scenedesmus obliquus) were higher at 13 degrees C than at 18 degrees C. At low temperatures, group M (Microcystis spp.) cannot successfully survive and grow at low temperatures, exhibiting various stress responses, such as inhibited photosynthetic activities and reduced phosphorous utilization. However, low temperature increased soluble carbohydrate contents of Microcystis, which favored the fast development of Microcystis, once the temperature warmed. Currently, climate warming is occurring in the Dianchi Lake basin; thus, future climate warming in winter (+/- 5 degrees C) may compromise the advantages of group J and promote the abundance of group M. The water transparency, dissolved oxygen and biodiversity in the lake would be further reduced. Furthermore, the increased microcystin and odor produced by Microcystis would considerably threaten the food web structure and lake ecosystem functions.

Enhanced N input to Lake Dianchi Basin from 1980 to 2010: Drivers and consequences

Due to a rapid increase in human population and development of neighborhood economy over the last few decades, nitrogen (N) and other nutrient inputs in Lake Dianchi drainage basin have increased dramatically, changing the lake's trophic classification from oligotrophic to eutrophic. Although human activities are considered as main causes for the degradation of water quality in the lake, a numerical analysis of the share of the effect of different anthropogenic factors is still largely unexplored. We use the net anthropogenic N input (NANI) method to estimate human-induced N inputs to the drainage basin from 1980 to 2010, which covers the period of dramatic socioeconomic and environmental changes. For the last three decades, NANI increased linearly by a factor of three, from 4700kgkm−2year−1 in 1980 to 12,600kgkm−2year−1 in 2010. The main reason for the rise of NANI was due to fertilizer N application as well as human food and animal feed imports. From the perspective of direct effects of food consumption on N inputs, contributions of drivers were estimated in terms of human population and human diet using the Logarithmic Mean Divisia Index (LMDI) factor decomposition method. Although human population density is highly correlated to NANI with a linear correlation coefficient of 0.999, human diet rather than human population is found to be the single largest driver of NANI change, accounting for 47% of total alteration, which illustrates that the role of population density in the change of NANI may be overestimated through simple relational analysis. The strong linear relationships (p<0.01) between NANI and total N concentrations in the lakes over time may indicate that N level in the lake is able to respond significantly to N inputs to the drainage basin.

Estimating net anthropogenic nitrogen inputs (NANI) in the Lake Dianchi basin of China

Abstract. Net anthropogenic nitrogen inputs (NANI) with components of atmospheric N deposition, synthetic N fertilizer, agricultural N fixation and N in net food and feed imports from 15 catchments in the Lake Dianchi basin were determined over an 11-year period (2000–2010). The 15 catchments range in size from 44 km2 to 316 km2 with an average of 175 km2. To reduce uncertainty from scale change methodology, results from data extraction by area-weighting and land use-weighting methods were compared. Results show that the methodology for extrapolating data from the county scale to watersheds has a great influence on NANI computation for catchments in the Lake Dianchi basin, and that estimates of NANI between the two methods have an average difference of 30% on a catchment basis, while a smaller difference (15%) was observed on the whole Lake Dianchi basin basis. The riverine N export has a stronger linear relationship with NANI computed by the land use-weighting method, which we believe is more reliable. Overall, nitrogen inputs assessed by the NANI approach for the Lake Dianchi basin are 9900 kg N km−2 yr−1, ranging from 6600 to 28 000 kg N km−2 yr−1 among the 15 catchments. Synthetic N fertilizer is the largest component of NANI in most subwatersheds. On average, riverine flux of nitrogen in catchments of the Lake Dianchi basin averages 83% of NANI, far higher than generally observed in North America and Europe. Saturated N sinks and a limited capacity for denitrification in rivers may be responsible for this high percentage of riverine N export. Overall, the NANI methodology should be applicable in small watersheds when sufficiently detailed data are available to estimate its components.

Design on the Optimal Diversion System of Sewage Interception System around Dianchi Lake

Dianchi water pollution control engineering has been carried out for decades. The point source pollution has been progressively effective controlled, while the non-point source pollution seems increasingly urgent. The Dianchi Link Lake sewage interception systems optimization diversion system is dveloped to exert integrated interception performance fully in Dianchi Link Lake interception system and research the optimal diversion programs of sewage interception systems in different areas of Dianchi Lake Basin. This paper describes the general idea, structure, function and technology roadmap of the system design. From the perspective of optimal diversion and decision supporting, the methods of computer running mode diversion, content and steps are found to provide new ideas for digital management and analysis of pollution in Dianchi Lake interception system.

Rural Water Environment and Domestic Wastewater Treatment Control Technique Analysis of Dianchi Lake Basin

The eutrophication problem of Dianchi Lake has been more and more serious. Based on the current situation of rural water environment,this paper carried out a survey of Dianchi Lake Basin rural water environment, in order to explore the proper technique for the local sewage pollution control. According to the water environment management requirements, this paper suggested the rural sewage treatment techniques and the treatment degree should be divided into four levels, provided a basis for Dianchi Lake Basin rural water environment control.

Design and Implementation of the Spatial Database for Reclaimed Water Utilization

In order to meet the application requirements of visual management and analysis of the information about recycled water use, the spatial database for the City Recycled Water Use is designed and constructed in this paper based on Geodatabase the spatial data model as well as UML and CASE as tools. The View Layer design, Concept design and Logic Design of the database of the recycled water use is explained in details. Then the application of the designed database to implement the Dianchi Lake Basin recycled water use in GIS platform is carried out and parts of the details is described in this paper.

The Thinking about Sewage Ecological Management of Villages and Small Towns in the Dianchi Lake Basin

In order to protect the Dianchi lake fundamentally, and to achieve the social and economics development sustainablely, an investigation of the sewage generation, emission and management current situation of villages and small towns in the Dianchi Lake basin was carried out. Based on the actual situation of the basin, this paper put forword methods of sewage ecological management., and explore three levels of management ideas for different pollution control requirements in every area of the basin. Keywords: The Dianchi Lake Basin; Sewage of Villages and Small Towns; Ecological Management

Based on Index Difference of River Water Quality Model and Application in Dianchi Lake Basin

Based on the river advection and diffusion process, the application of mass balance principle, a suitable diffusion model in Dianchi Lake Basin rivers burst water pollution emergency treatment. River water quality model based on the exponential difference solving simulated the spatial and temporal distribution of pollutants in the sudden water pollution accidents. This paper quantitatively simulated time and concentration values at the different locations of the river downstream of the pollutants reach Finally, GIS technology to achieve the simulation results of the real-time dynamic visualization.

Combining the SWAT model with sequential uncertainty fitting algorithm for streamflow prediction and uncertainty analysis for the Lake Dianchi Basin, China

Streams play an important role in linking the land with lakes. Nutrients released from agricultural or urban sources flow via streams to lakes, causing water quality deterioration and eutrophication. Therefore, accurate simulation of streamflow is helpful for water quality improvement in lake basins. Lake Dianchi has been listed in the ‘Three Important Lakes Restoration Act’ in China, and the degradation of its water quality has been of great concern since the 1980s. To assist environmental decision making, it is important to assess and predict hydrological processes at the basin scale. This study evaluated the performance of the soil and water assessment tool (SWAT) and the feasibility of using this model as a decision support tool for predicting streamflow in the Lake Dianchi Basin. The model was calibrated and validated using monthly observed streamflow values at three flow stations within the Lake Dianchi Basin through application of the sequential uncertainty fitting algorithm (SUFI-2). The results of the autocalibration method for calibrating and the prediction uncertainty from different sources were also examined. Together, the p-factor (the percentage of measured data bracketed by 95% prediction of uncertainty, or 95PPU) and the r-factor (the average thickness of the 95PPU band divided by the standard deviation of the measured data) indicated the strength of the calibration and uncertainty analysis. The results showed that the SUFI-2 algorithm performed better than the autocalibration method. Comparison of the SUFI-2 algorithm and autocalibration results showed that some snowmelt factors were sensitive to model output upstream at the Panlongjiang flow station. The 95PPU captured more than 70% of the observed streamflow at the three flow stations. The corresponding p-factors and r-factors suggested that some flow stations had relatively large uncertainty, especially in the prediction of some peak flows. Although uncertainty existed, statistical criteria including R2 and Nash–Sutcliffe efficiency were reasonably determined. The model produced a useful result and can be used for further applications. Copyright © 2012 John Wiley & Sons, Ltd.

Evaluating Quantitative and Qualitative Models: An Application for Eco-Environmental Quality Evaluation in Lake Dianchi Basin, China

Considering the various influencing factors of eco-environmental quality in Lake Dianchi Basin, the evaluation indexes of eco-environmental quality such as biological abundance index, vegetation coverage index, water network density index, land degradation index and environmental quality index are determined. The weight values of factor indexes are given by using the quantitative and qualitative model of analytic hierarchy process (AHP) and the eco-environmental quality of Lake Dianchi Basin was evaluated by using the quantitative and qualitative model of ecological index (EI). The evaluation results show that the grade of eco-environmental quality is weaker and the environment for human survival is harsh. The evaluation result is in good agreement with the results of previous studies. The evaluation system established in the paper can be regarded as a reference model for eco-environmental quality evaluation.

Impacts of 20-year socio-economic development on aquatic environment of Lake Dianchi Basin

Lake Dianchi is a famous plateau freshwater lake,whose basin is the most active area of socio-economy in Yunnan Province.Through systematic investigation socio-economic development and changes of aquatic environment in 1988-2009,the main influencing factors of such changes were analyzed.Results showed that the annual increasing rate of population,GDP,and urbanization in the Lake Dianchi Basin reached 3.3%,18%,17% in recent 20 years,respectively;With the rapid development in socio-economy,total water consumptions and pollutant emissions continuously increased.At the same time,the water quality in main rivers deteriorated significantly,with the percentage of rivers with water quality type-Ⅴ increased by nearly 4 times.The water quality of inner(Lake Caohai) and outside of the lake were degraded to worse than type-Ⅴ.The deterioration of water quality and lake eutrophication have become important water environmental problems in Lake Dianchi,which are difficult to be relieved in the short term.In the basis,we proposed some measures and recommendations to improve the water environment in the basin,including optimizing industrial structures,construction of sewage treatment systems,wastewater reclamation,rural environmental protection,ecological compensation mechanism and so on.

Study on the Risk Pattern of Non-Point Source Pollution Using GIS Technology in the Dianchi Lake Watershed

A rapid quantitative risk evaluation system of non-point source pollution (NPSP), based on comprehensive consideration of various factors such as topographic features, land use construction, annual mean precipitation, soil erosion characteristics and pollutant removal cost, was constructed using an Spatial Analysis Module of GIS on watershed scale. We investigated the risk pattern of NPSP in the Dianchi Lake Watershed using the rapid risk assessment system. The results indicated that NPSP risk pattern showed the arc or normal distribution trend in the Dianchi Lake Basin, namely the medium risk area of NPSP is the largest (about 1311 km2). Moreover, the spatial difference of high risk NPSP pattern is remarkable: the high risk region for NPSP was primarily in the 10 km range of the southern and eastern parts and the 5 km range of western part around the Dianchi Lake.

Evaluation of Eco-environmental Sensitivity in Lake Dianchi Basin Based on the Fractal Analysis

Evaluation of Eco-environmental Sensitivity in Lake Dianchi Basin Based on the Fractal Analysis

Exploring factors shaping population genetic structure of the freshwater fish Sinocyclocheilus grahami (Teleostei, Cyprinidae)

Phylogeographical analyses on Sinocyclocheilus grahami samples from seven localities within the Lake Dianchi Basin in China were conducted to explore the main factors shaping population structure within this species. Phylogenetic and network analyses revealed two major clades in 24 mtDNA haplotypes. One clade included three haplotypes exclusively from samples of the lower basin and another clade encompassed other haplotypes from samples of the upper basin. The estimated divergence time between the two clades predated the river capture event connecting the lower and upper lake basin and thus supported geographical isolation as the main factor shaping genetic divergence between these two clades. Furthermore, analysis of molecular variance and pair-wise Phi(ST) distances revealed significant genetic differentiation within the upper basin. Mantel tests clearly supported patterns of differentiation arose purely as a result of isolation by distance. These results further highlight the importance of geographical isolation in shaping differentiation within this species.

Simulation of non-point source pollution in watershed scale: the case of application in Dianchi Lake Basin

Watershed water quality management is a process with many steps. Mathematical model plays an important role in watershed management as it can resolve the problem quantificationally and be operated dynamically. HSPF (Hydrological Simulation Program Fortran) developed by USEPA was chosen for the application in this paper. Hydrology and water quality simulation processes in the non-point source pollution model were introduced in the study, in which Dianchi Lake Basin was chosen for the case study. The whole basin was divided into nine sub-basins firstly. Then the non-point source database for the Dianchi Lake Basin was built. Sensitivity analysis revealed that only a few parameters were sensitive to the simulation of runoff and water quality processes. In the paper, the simulation processes for river outflow, SS, BOD, TN and TP were introduced in detail. The simulation processes for Panlongjiang Sub-watershed was given as an example. Parameter values were estimated from watershed properties, previous experimental and modeling studies, regional field studies and literature. Optimization of the parameter values, calibration of the model and validation of the simulation was achieved using stream flow and concentration of pollutants in the river outflow of watershed. The simulation results showed that relative error for runoff simulation in some sub-watersheds was very small. On the whole, the runoff simulation results were good. After that, the total and non-point source pollution loads of SS, BOD, TN and TP in each sub-watershed were calculated using the calibrated model. The results revealed that the main contributors of the non-point source pollution in the Dianchi Lake Basin were SS, TN and TP. From the spatial distribution to the non-point sources, nitrogen pollution mostly came from Panlongjiang, Baoxianghe and Chaidahe sub-watersheds. It could be attributed to the large amount usage of fertilizers in agricultural lands. SS and TP pollution status was serious in Chaidahe sub-watershed and western diffused area. The main reason could be explained as many phosphorite mines were distributed in such areas. High water and soil runoff and phosphorous adsorption had caused high non-point source pollution in total phosphorous.

Study on the Divisions of Non-Point Pollution Sources in Dianchi Lake Basin

Study on the Divisions of Non-Point Pollution Sources in Dianchi Lake Basin

Prediction of eutrophication of dianchi lake

本文采用多元线性回归及合田健模型分别对滇池有机污染及富营养化的主要因子COD、TN、TP进行预测, 并将污染负荷量分至各点源。定量说明污水处理厂对治理城市污水的积极作用, 为流域进行污染治理提供了科学依据。;Organic pollution and eutrophication of Dianchi Lake are getting aggravated as a result ofurban domestic sewage.In order to better understand the trend in water pollution of DianchiLake，such main factors reflecting the organic pollution and eutrophication of Dianchi Lake as COD，ON and TP are predicted by means of a multivariate linear regression and Ken KodaModel，and by allocating the pollution loads to each point source.In addition，the active roleplayed by the wastewater treatment plantin control lingur bansewageis quantitatively expounded to provide a scientific basis for the control of water pollution in Dianchi Lake basin.