Dianchi Lake Basin Research Articles

Predicting hydrological alterations to quantitative and localized climate change in plateau regions: A case study of the Lake Dianchi Basin, China

Predicting hydrological alterations to quantitative and localized climate change in plateau regions: A case study of the Lake Dianchi Basin, China

Effects of pH on the dynamic migration of nutrient salts in the sediment of ditches in mountain rural areas

Objective As pH is a key factor affecting the migration and release of nutrients in the ditch sediment, this study, with an investigation of the dynamic changes of nutrient release and migration in the bottom mud of mountainous rural ditches under different pH conditions, is aimed to provide a theoretical basis for rural ecological environment management. Method With the bottom mud of typical mountainous rural ditches in the Dianchi Lake Basin collected, indoor simulation experiments were conducted to determine the nutrient salt content of the bottom mud and the overlying water under different pH (pH 5.5, 7.5, 9.5, 11.5) conditions under non-sterilized and sterilized treatments after which the nutrient release flux at the sediment-water interface was estimated. Result The mass fraction of total nitrogen (TN) in the bottom sludge decreased with the increase of pH. The total nitrogen release flux under the strong alkaline (pH 11.5) and acidic (pH 5.5) conditions of the non-sterilized group was 8 and 4 times of the control (pH 7.5), and its release flux in the sterilization group was 2 times of that in the control. The mass concentration and release flux of soluble total phosphorus (DTP) in the overlying water increased with the increase of pH. The release of DTP under the conditions of strong alkaline (pH 11.5) and weak alkaline (pH 9.5) in the non-sterilized group was 12 and 4 times of that in the control, respectively, and its release flux in the sterilized group was 30 and 15 times of that in the control while the non-sterilized group had higher DTP release flux than the sterilized group. RDA shows that acidic conditions promote the release of calcium-bound phosphorus (Ca-P) in sediments, and alkaline (pH≥9.5) conditions promote the release of total nitrogen, total phosphorus and iron-aluminum-bound phosphorus (Fe/Al-P). Neutral (pH 7.5) conditions have little effect on the release of nitrogen or phosphorus in the sediments. Conclusion Alkalinity (pH≥9.5) and acidity significantly promote the release of nitrogen and phosphorus nutrients in the bottom mud of mountain rural ditches, and the release amount is the smallest under neutral conditions. Also, the sterilization of the bottom sludge reduces the microbial activity at different pH levels, and prevents the migration and release of nitrogen and phosphorus in the bottom sludge of mountain and rural ditches to the overlying water. [Ch, 6 fig. 1 tab. 36 ref.]

Impacts of rapid urbanization on ecosystem services under different scenarios – A case study in Dianchi Lake Basin, China

Dianchi Lake Basin (DLB) is a typical and representative type of urbanization model based on the plateau lake ecosystem, with scarce land resources, deficient water resources, and a fragile ecological environment, in parallel with large-scale and rapid urbanization. To increase ecological security and maintain ecosystem services (ESs), it is essential to analyzethe paths and processes for implementing sustainable urbanization. Using combined CLUE-S-Markov-InVEST modeling, the study simulated ESs changes and distribution in DLB under a natural increase scenario (NIS), an urban plan scenario (UPS), and an ecological protection scenario (EPS). EPS proved to be the best-optimized urbanization path and land use pattern that can meet land use demand for urbanization, but also maintain (or even improve) regional ESs levels. The major driving mechanisms underlying urbanization effects on ESs were found to be selection of urbanization path, scale control and layout of construction land, demarcation and implementation of ecological red line and ecological protection areas. The results indicate that DLB should follow the EPS urbanization path, an ecological red line should be reasonably delineated and observed, and ecological isolation strips should be established at appropriate locations. Additionally, the scale of construction land should be strictly controlled, constructed land should be used more intensively, and the utilization efficiencyof construction land should be improved.

Impacts of Urban Land Use Changes on Ecosystem Services in Dianchi Lake Basin, China

Land use change is widely regarded as a key factor altering the structure and function of ecosystems. Urbanization is a particular driver and influence in land use change and is expanding globally, especially in developing countries like China. The InVEST model was employed in this study to comprehensively assess the temporal-spatial impacts of urban land use changes (ULUC) on ecosystem services (ESs) and clarify the tradeoffs between urbanization and ecosystem services provision (ESP) in Dianchi Lake Basin (DLB), China, during 1995–2015. The results showed that DLB’s constructed land, particularly in lakeside areas, has increased substantially because of rapid urbanization (built-up area increase 51%, urbanization rate increase 91%), at the expense of agriculture, grassland, and scrubland, greatly altering ESP. Compared with 1995, carbon storage in 2015 decreased, while soil retention and nitrogen exports only fluctuated slightly. Although water yield increased, the ecological water volume of the whole DLB decreased through an increase in regional surface runoff. This resulted in more pollutants being carried into Dianchi Lake, impairing water quality and causing serious ecological and environmental issues. Thus, this study provides empirical evidence of the significant influence of ULUC on ESP. For eco-friendly urbanization in DLB and similar areas with rapid urbanization, a sustainable pattern of urbanization should be followed. The best tradeoffs between urbanization and ESP should be identified and considered in decision-making relating to urban planning, land use management, optimal natural resources management, and ecological conservation.

Dynamic evaluation of water resources carrying capacity of the Dianchi Lake Basin in 2005–2015, based on DSPERM framework model and simulated annealing-projection pursuit model

With the intensified impact of human activities, most lakes have been severely disturbed and the lake ecosystem has been seriously damaged, which exerted a great impact on the living environment of human beings in the lake basins. The health of the lake ecosystem has gradually become one of the hot issues in recent years. In this study, the water resources carrying capacity (WRCC) was used to reveal the chain relationship between human activities and water environment in the economic development of the Dianchi Lake Basin in Kunming City of China during 2005–2015. Specifically, we chose 25 evaluation indicators related to the water environment and social-economic activities, classified them into six subsystems, i.e., the driving force subsystem (D), the water resources situation and consumption subsystem (S), the water resources pressure subsystem (P), the water environmental situation subsystem (E), the response subsystem (R), and the management subsystem (M), and built a comprehensive assessment system-DSPERM framework model. Simulated annealing-projection pursuit model which reflects the structure or feature of high-dimensional data was adopted to calculate the WRCC of the Dianchi Lake Basin during 2005–2015 by weighting each evaluation indicator and each subsystem of the DSPERM framework model. The results show that the WRCC of the Dianchi Lake Basin was in level III (medium carrying capacity) from 2005 to 2012. Since 2013, the WRCC has been at level II (strong carrying capacity), and from 2005 to 2015, it showed a gradual upward trend. The evaluation indicators of each subsystem varied greatly and exhibited different development trends. The indicators of the water resources pressure subsystem had the greatest impact on the WRCC, followed by the indicators of the water environmental situation subsystem and the water resources situation and consumption subsystem. We recommend that the DSPERM framework model and the simulated annealing-projection pursuit model constructed in this work can be used to analyze the dynamic changes of the WRCC over the years. They have the advantages of practicability and feasibility, and can provide the basis for the scientific decision-making and comprehensive management of regional water environment planning.

Variation characteristics of surface temperature in Dianchi Lake Basin in recent 20 years

The ecological environment of the earth has changed with the development of economy. These changes also have an impact on human’s life. We can know that the average annual temperature in the Dianchi Lake Basin has shown an upward trend in the past 20 years through the analysis of temperature changes in the Dianchi Lake Basin. In the four seasons, there are various degrees of sudden changes, especially in autumn, the temperature rising trend is the most significant, and there is a downward trend in winter but the downward trend is not obvious. From the analysis of monthly average temperature data, it can be seen that the temperature is rising except for April and August, and the rising trend is also obvious in October, November and December.

Analysis on the Characteristics of Cultivated Land Change in DianChi Lake Basin based on remote sensing image processing technonlogy in the past 20 years

Cultivated land is the fundamental guarantee of agricultural production, accurate acquisition of information such as the area and distribution of cultivated land and the change characteristics of cultivated land is of great significance for agricultural resource monitoring and production. The development of remote sensing technology provides a new technical scheme for rapid and efficient extraction of cultivated land information. This article takes Dianchi Lake Basin as the research object to study the characteristics of cultivated land changes in Dianchi Lake Basin in the past 20 years. In the past 20 years, the distribution of cultivated land in the dianchi lake basin gradually changed from species concentration to decentralization, and showed a trend of gradually moving away from dianchi lake. Through the analysis of the dynamic attitude of land use, it is found that the cultivated land area in the dianchi basin has significantly changed between the land use in the past 20 years. From the perspective of the change trend and state index of single land use in the dianchi lake basin, the bidirectional transition of all land use in the region is frequent and extremely unbalanced. The area converted from cultivated land to non-cultivated land is larger than the area converted from non-cultivated land to this type. It develops towards the direction of scale reduction and is in the state of “falling trend”.

Environmental Threshold of Phosphorus Infiltration in Red Soil under Different Land Use Patterns

The risk of soil phosphorus leaching increases in basin regions in light of large-scale use of phosphorus fertilizers because of agricultural modernization. In this study, we conducted an earth pillar simulation test on the infiltration threshold of red soil, Vaseline-coated PVC pipe, intact soil core, fine sand, and nylon filter was used for Penetration test, which covers the largest area of the Dianchi Lake Basin in China. Results showed that: 1) The contents of the total available phosphorus in algae (NaOH-P) and dissolved labile phosphorus (CaCl2-P) in red soil were consistent with the content of available phosphorus (Olsen-P) under different use patterns manifested by the law of greenhouse > open field > grassland. Grassland had the highest phosphorus sorption index (PSI), followed by the greenhouse and then by the open field. 2) The leachate under the same use pattern had the characteristics of total phosphorus (TP) > particle phosphorus (PP) > total dissolved phosphorus (TDP) > dissolved organic phosphorus (DOP) > molybdate reactive phosphorus (MRP). The TP contents in the leachates of grassland, greenhouse, and open field were 0.46, 0.61, and 0.49 mg/L, respectively. DOP, TDP, PP, and MRP had similar contents, and their distributions in the three land types were consistent with that of TP. 3) Olsen-P had a significant correlation with TP, TDP, PP, and DOP in the leachates. Olsen-P of 50 slightly influenced eutrophication. Moreover, Olsen-P of >40 and 40 had minimal influence on the environment. Olsen-P of >70.90 mg/kg and PSI of 26.09 mg/kg, the TP content in the leachate increased sharply.

Sewage Treatment System Planning for Dianchi Urban Wetland Park in Kunming

Dianchi Lake urban wetland park in Kunming is an important component of Dianchi lakeside wetlands, it is of great significance to the urban development and ecological protection of Kunming. To solve the problem of non-point source pollution of Dianchi Lake basin, the Dianchi Lake Pan-Asian International Urban Wetland Park is taken as an example, the rapid artificial infiltration treatment system and the comprehensive constructed wetland treatment system were designed for Dianchi Lake urban wetland park, and various design parameters and its influencing factors have been analyzed. After the deep treatment by the treatment system, the water quality reached the standards of landscape water. The planning of water system for Dianchi Lake urban wetland park provides a reference for designing plateau lake urban wetland parks.

Quantification of the Coordination Degree between Dianchi Lake Protection and Watershed Social-Economic Development: A Scenario-Based Analysis

Dianchi Lake is the largest freshwater lake on the Yunnan–Guizhou Plateau near Kunming City, China. As one of the most polluted lakes in China, although billions of U.S. dollars have been spent trying to clean it up, water pollution and eutrophication are still a bottleneck for regional sustainable development. This research established an integrated approach for the evaluation of the coupling coordination degree to support future planning of the Dianchi Lake basin. Ten future scenarios for possible development directions of Dianchi Lake basin were designed to find the best balance between development and protection. Among these scenarios, a high protection–medium development scenario is the most suitable scenario for future development planning. To further improve the coordination degree, economic growth control and non-point source governance were the most effective and feasible approaches. Furthermore, a water quality model was used to verify the coordination degree. It was found that the high protection–medium development scenario can reach the water quality target in 2025. The coordination degree evaluation could be a practical link to help equilibrate the socio-economic development and environmental protection of the Dianchi Lake basin.

Response of river-lake hydrologic regimes to local climate change in the Yunnan-Guizhou Plateau region, China

Climate change affects hydrological regimes by influencing precipitation and air temperature. The climate change effects on lake hydrology in the Yunnan-Guizhou Plateau of China remain unclear. Lake Dianchi, the Plateau’s largest lake subject to human interference, was selected for the study. Algorithms based on historical meteorological data produced high-resolution climate change scenarios describing climate characteristics at a local watershed scale. Integrated river and lake hydrological models simulated changes in inflow, lake volume, and hydrological extremes under different scenarios. Results showed that Lake Dianchi Basin (LDB) inflow would decrease by 1.88~2.21% if air temperature increased by 1~2 °C but increase by 1.23~16.1% if precipitation increased by 5~20%. Lake volume would change minimally (decrease of 0.87~1.15%) if air temperature increased 1~2 °C and if precipitation increased 5~20% (increase of 0.04~4.12%); thus, the hydrological regimes of LDB are more sensitive to precipitation than air temperature. Changes to 3-day and 7-day maximum hydrological extremes were double those of 3-day and 7-day minimums, indicating precipitation-affected maximum extreme hydrological events during wet season more than minimum extreme hydrological events during dry season. In conclusion, both unevenly distributed precipitation and increasing air temperature will increase wet season floods and dry-season droughts in plateau lakes like Lake Dianchi.

Structure of Bacterial Communities in Phosphorus-Enriched Rhizosphere Soils

Although phytoremediation is the main method for P-removal and maintaining ecosystem balance in geological phosphorus-enriched soils (PES), little is known about the structure and function of microbial communities in PES. Interactions between plants and soil microorganisms mainly occur in the rhizosphere. The aim of this work was to investigate the composition and diversity of bacterial communities found in rhizosphere soils associated with the following three dominant plant species: Erianthus rufipilus, Coriaria nepalensis, and Pinus yunnanensis. In addition, we compared these rhizosphere bacterial communities with those derived from bulk soils and grassland plots in PES from the Dianchi Lake basin of southwestern China. The Illumina MiSeq platform for high-throughput sequencing of 16S rRNA was used for the taxonomy and the analysis of soil bacterial communities. The results showed higher bacterial diversity and nutrient content in rhizosphere soils as compared with bulk soils. Rhizosphere bacteria were predominantly comprised of Proteobacteria (24.43%) and Acidobacteria (21.09%), followed by Verrucomicrobia (19.48%) and Planctomycetes (9.20%). A comparison of rhizosphere soils of the selected plant species in our study and the grassland plots showed that Acidobacteria were the most abundant in the rhizosphere soil of E. rufipilus; Bradyrhizobiaceae and Rhizobiaceae in the order Rhizobiales from C. nepalensis were found to have the greatest abundance; and Verrucomicrobia and Planctomycetes were in higher abundance in P. yunnanensis rhizosphere soils and in grassland plots. A redundancy analysis revealed that bacterial abundance and diversity were mainly influenced by soil water content, soil organic matter, and total nitrogen.

An uncertainty-based multivariate statistical approach to predict crop water footprint under climate change: a case study of Lake Dianchi Basin, China

Agricultural water sustainability in a basin environment experiencing climate change has become a critical issue in the past few decades. This study used the DPSIR (Driver–Pressure–State–Impact–Response) framework as a conceptual basis to explore the relationship between water footprint (WF) trends and climate change and agricultural-economic variation. With the aim of mitigating water crisis and ensuring robust responses to the uncertainty of the future, an uncertainty-based multivariate statistical approach was proposed for WF prediction by using various scenarios combined with multiple linear regression and Monte Carlo simulation. Lake Dianchi in China was used as the case study area. The results indicate that (1) the total WF had an increasing trend of 394.39 m3 ton−1 year−1; the WFgreen (the precipitation used in the crop production process) had a decreasing trend, while the WFblue (the irrigation water withdrawn from the ground or surface water) and WFgrey (the water used to dilute the load of pollutants, based on existing ambient water quality standards) exhibited an increasing trend; (2) the total WF showed a distinct increasing trend under climate change and agricultural-economic variation due to the increase of the WFgrey during 1981–2011; and (3) the impact of agricultural-economic factors on WF trends, especially on the WFblue and WFgrey, far outweighed the impact of climatic factors under the alternative scenarios. Our results suggest that adaptive management of anthropogenic activities should be prioritized to mitigate water stress under climate change.

Pollutant removal from agricultural drainage water using a novel double-layer ditch with biofilm carriers

Agricultural drainage ditches can prevent flooding and mitigate agricultural pollution; however, the performance is unsatisfactory in plateau areas like the Dianchi Lake basin. Thus, a novel double-layer ditch system (DDS) with a fibrous packing as biofilm carriers was developed to form the carrier-attached biofilms and enhance the pollutant removal. The results indicated the DDS performed better than a single-layer ditch system, and annual average removal efficiencies of TN, NO3−-N, NH4+-N, TP, COD and SS were 18.61%, 17.13%, 7.74%, 11.90%, 11.95% and 23.71%, respectively. High amount and carbon, nitrogen and phosphorus contents of biofilms are favourable to pollutant removal by DDS. Although bacterial diversity of biofilms remained relatively stable throughout the year, the relative abundance of dominant assemblages varied greatly. Denitrifying microorganisms affiliated with Bacteroidetes might contribute to effective NO3−-N reduction. This study demonstrates DDS performed well and provides a novel method for application of biofilm carriers in drainage ditches.

Influence of nutrient mitigation measures on the fractional export of watershed inputs in an urban watershed.

Enhanced nutrient inputs due to human activities have been noted as a significant driving force for riverine nutrient exports which are responsible for the eutrophication issues in freshwaters. Current studies are mostly focused on the relationship between anthropogenic inputs and riverine exports, and little has been done to assess the role of nutrient mitigation measures in the fractional export of watershed nutrient inputs in urban regions. A highly urbanized watershed in Yun-Gui plateau of China, Lake Dianchi basin was studied as a case to assess the impact of nutrient mitigation measures on riverine nutrient exports. Based on net anthropogenic nitrogen and phosphorus inputs (NANI and NAPI, respectively) models, nutrient inputs from human activities in the basin from 1980 to 2015 were calculated, and the impact of nutrient mitigation measures were identified using a statistical model incorporating land use, precipitation, and temperature. Nutrient inputs from human action in the basin has increased rapidly, mainly from fertilizer application and food and feed imports. Enhanced riverine nutrient exports were found at the same time, and significantly correlated to nutrient inputs. The construction of water transfer projects and wastewater treatment plants in the basin has changed the controlling factors and processes of the fractional export of watershed nutrient inputs, which is weak in explanatory ability and eliminated the role of the land use. A modified model was established by incorporating the effect of water transfer projects and wastewater treatment plants, which showed a significant increase in model performance. The results from the modified model reveal that urban land percentage has become a positively driving force for the fractional export of watershed N and P inputs, and temperature a positive driving force for the fractional export of watershed N inputs while precipitation a negative driving force for the fractional export of watershed P inputs.

Design of An Intelligent System for Monitoring and Management in Sewage Treatment Plants Based on IoT

Due to the large number of sources and wide area of domestic sewage, the sewage treatment facilities in Kunming are mainly distributed in scattered market towns and villages and have a wide variety. With the wide application of IoT technology, sewage treatment plants are heading towards intelligence and unmanned technology, with better treatment monitoring, higher treatment quality and lower operation cost. Based on IoT technology, this paper constructed an intelligent system for monitoring and management in sewage treatment plants in Dianchi lake basin and Niulan river basin. The overall architecture of the system was achieved by modularized function design, and was divided into three systems : device end system, network transmission system and application management system. This system realizing centralized management and display can monitor the operating status of sewage treatment process online, improve the efficiency of facility management and operation, as well as the work efficiency of relevant departments. The dilemma related to sewage management in Dianchi lake basin and Niulan river basin can be solved significantly.

Simulation and engineering demonstration of the advanced treatment of rainy overflow wastewater using a combined system of storage tank-wastewater treatment plant-wetland.

We propose a new technology to advanced treat overflow wastewater from a combined sewer system using a storage tank-wastewater treatment plant (STP)-constructed wetland (CW) system. The engineering demonstration (a 7,500m3 storage tank and a 3,436m2 CW) has been built to treat the combined sewer overflows (CSOs) at the largest combined rainwater/wastewater overflow outlet in the middle reaches of the Xinbaoxiang River, which is the second largest river in the Dianchi Lake Basin. During the rainfall period, CSOs enter the storage tank. After sedimentation purification, the higher concentration CSOs at the bottom enter the STP, and the upper low-concentration CSOs enter CWs, thereby linking the multiple means of treating CSOs and minimizing the impact of CSOs on the STP. During the dry season, CWs can also assist in purification of polluted river water. The supernatant (COD <80mg/L) and the bottom part water (COD >200mg/L) of the storagetank were sent to CWs and STP, respectively, for treatment. The project was stably operated over 6months. The final effluent qualities were 12, 1.79, and 0.18mg/L for COD, TN, and TP, respectively, which achieved the surface water class V standard. PRACTITIONER POINTS: A combined system of storage tank-wastewater treatment plant-wetland was proposed to advanced treat overflow wastewater of rainy season. The SWMM could calculate the water quality and volume of overflow under different rainfall conditions in the runoff area. The effluent of the engineering demonstration reached the standard of surface water class V.

Effects of Straw Mulching on Microbial Quantity in Maize and Broccoli Soil in Dianchi Lake Basin

Field experiments were conducted in Dianchi basin to study the effects of straw mulching on the quantity of ammoniated bacteria, actinomycetes, and fungi in maize and broccoli soil, using dilution plate counting method. The results showed that: (1) Compared with bare soil and uncovered soil, plastic mulching and straw mulching could increase the number of microorganisms in Maize soil. Straw mulching could significantly increase the number of fungi in maize soil, reaching 6.5×104 CFU·g−1 dry soil, which was 2.0, 1.4 and 2.7 times as much as that of plastic mulching, uncovered and bare soil respectively. The effects of straw mulching and plastic mulching on the number of other types of microorganisms in maize soils were not significantly different. (2) Compared with bare soil, straw mulching could increase the number of fungi in broccoli soil by 83%, and plastic mulching could increase the number of actinomycetes and fungi. Straw mulching could increase the number of microorganisms in soils, which is of great significance to clarify the microbial mechanism of straw mulching to reduce non-point source pollution.

The study on the drive mechanism and prediction of the impervious surface expansion with index of entropy

Index of entropy was adopted to mine the drive mechanisms for impervious surface (IS) expansion. With rapid urbanisation, the effects of the spread and growth of the impervious surface on eco-environmental are profound. Thus, studying the interior mechanism of impervious surface expansions have becoming more significant. The results show that the number of neighbourhood impervious surface is of the overriding factor with the influence weight of 0.057554; the second are GDP and housing price with the weight of 0.037747, 0.036875, respectively; the thirdly factors are population density and DEM with the effect weight of 0.026878 and 0.020955, respectively. It can be deduce that the main factors of the impervious surface expansion are social-economic factors. Finally, we predicted the expansion of the impervious surface from 2002 to 2020. Compared with the classification map of the impervious surface, the simulation accuracy is 82.36% using the point to point model. And the accuracy of the kappa coefficient is 87.15% about impervious surface, and 89.31% for pervious surface, indicating that the model is relatively reliable to simulate the impervious surface expansion, and the spatial distribution of simulation results are consistent with the actual classification of the impervious surface in the Dianchi Lake basin.

Landscape Ecological Risk Assessment of Dianchi Lake Basin Based on Land Use Change

In order to explore the impact of land use type change on landscape ecological risk, this paper uses Landsat remote sensing image of Dianchi Lake Basin in 2003-2018 as the basis data to interpret its land use type by ENVI, and combines ArcGIS and Fragstats4.2 according to landscape ecology theory. The various landscape ecological indices were calculated, and the spatial pattern and process characteristics of landscape ecological risk in Dianchi Lake Basin from 2003 to 2018 were analyzed. The results show that: (1) The landscape pattern of Dianchi Lake Basin has changed significantly in 2003-2018. (2) The landscape ecological risk level has a gradually increasing trend, that is, the proportion of the medium risk area to the high-risk area is relatively large. (3) From the perspective of spatial distribution, the overall risk distribution of Dianchi Lake Basin has an increasing trend from Dianchi Lake to Dianchi Lake.