A GIS-based Spatial Analysis of Housing Price and Road Density in Proximity to Urban Lakes in Wuhan City, China

As one of the essential urban open spaces, lakes usually contribute immensely to the quality of residents′ daily lives. Different from hedonic approach employed in existing researches on urban open spaces in China, this paper integrates housing price surface with road density to analyze the spatial characteristics in proximity to urban lakes in Wuhan City, China. With the expansion of Wuhan City, urban lakes became polluted, they shrunk or even disappeared, leading to unfavorable conditions for sustainable development of the city. To better understand the spatial relationship between the city and lakes, we classify the urban lakes in Wuhan central area into ′lakes in the urban center′ and ′lakes in urban fringe′. Based on housing price surface we explore the spatial characteristics in proximity to different lakes and differences between the lakes. We also use Geographic Information System(GIS) tool to calculate road density as a supplementary indicator to reflect the accessibility in proximity to urban lakes. The results indicate that relative independence exists between different towns, and the spatial characteristics are different depending on scales and locations. In most of cases, the road density is lower where closer to the lakeshore while the housing price exhibits an opposite pattern. We conclude that city governments and urban planners should give more considerations to these spatial differences, somewhere should be better planned and protected as an important waterfront and somewhere the control of unreasonable real estate development nearby should be strengthened.

Simulation of internal nitrogen release from bottom sediments in an urban lake using a nitrogen flux model

Nutrient release from sediment is considered a significant source for overlying water. Given that nutrient release mechanisms in sediment are complex and difficult to simulate, traditional approaches commonly use assigned parameter values to simulate these processes. In this study, a nitrogen flux model was developed and coupled with the water quality model of an urban lake. After parameter sensitivity analyses and model calibration and validation, this model was used to simulate nitrogen exchange at the sediment–water interface in eight scenarios. The results showed that sediment acted as a buffer in the sediment–water system. It could store or release nitrogen at any time, regulate the distribution of nitrogen between sediment and the water column, and provide algae with nitrogen. The most effective way to reduce nitrogen levels in urban lakes within a short time is to reduce external nitrogen loadings. However, sediment release might continue to contribute to the water column until a new balance is achieved. Therefore, effective measures for reducing sediment nitrogen should be developed as supplementary measures. Furthermore, model parameter sensitivity should be individually examined for different research subjects.

Sustainability of Urban Lakes： Role of Values in Lake Governance in Ahmedabad, India

Lakes have different social, economical, and ecological values at different periods of societal development, which make them vulnerable to change. One of the ongoing discussions in urban lake governance in India is the revitalization of the urban lakes. The core challenge documented in the governance of urban lakes is to address and find balance in the changing and competing value systems. Effectively addressing the change （or priority） in the values linked to the governance systems is a major step toward sustainability of the urban lakes. There is still limited understanding of how the values of urban lakes are progressively linked to the social, ecological and economic values of the urban developments. The paper looks at the interactions and outcomes of the spatial and temporal dynamics of the urban lakes systems especially the values that sustain the institutional and ecological memory. The focus is on the role of values in urban lake governance. The multitier framework for analyzing social-ecological systems CSES） which is in developmental phase at Elinor Ostrom＇s Workshop is used as the guiding framework to build understanding of the urban lake governance in Ahmedabad, India and at the same time contribute to the development of the SES framework.

CONCENTRATIONS OF Cd, Cu AND Zn IN SEDIMENTS COLLECTED FROM URBAN LAKES AT KELANA JAYA, PENINSULAR MALAYSIA

Kelana Jaya Municipal Park is a popular recreation park in Petaling Jaya. The five lakes, located within the Park, were ex-mining ponds, functioning as flood retention ponds and receiving effluents from nearby human activities mainly from residents and transportation. A study was conducted to determine the distribution and sources of heavy metals (Cd, Cu and Zn) in the sediments of Kelana Jaya Lakes. Concentrations of Cd, Cu, and Zn for surface sediment were determined by using aqua-regia method and sequential extraction technique. Total Cd concentrations ranged from 0.48 μg/g to 2.68 μg/g dry weight (dw) for all lakes. Total Cd concentrations in sediment of all lakes exceeded CCME (Canadian Council of Ministers of the Environment, 2001) guidelines. Total Cu concentrations ranged from 7.37 μg/g to 73.6 μg/g (dw). Only Cu concentration in one lake exceeded the CCME guidelines besides having the highest mean concentration among all. Total Zn concentrations ranged from 107 μg/g to 529 μg/g (dw). Again, The Zn concentrations in three lakes were found to exceed CCME guidelines for Zn concentration in freshwater sediment. Geochemical study on sediment revealed that nonresistant fractions for Cd, Cu and Zn for other lakes there were higher than ‘resistant’ fraction. The elevated levels and most percentages (>50%) of nonresistant fractions of Cu and Zn indicated that lakes in the park, especially near oxidation pond and monsoon drains, could have received anthropogenic metals from domestic wastes. Rehabilitation program and regular biomonitoring at Kelana Jaya Lakes are therefore recommended.

Application of GDAHP on Quality Evaluation of Urban Lake Landscape

The quality evaluation of urban lake landscape (QEULL) is extremely important for the healthy development of lake landscape. In this research, the evaluation model was established with the group decision analytic hierarchy process (GDAHP) method, which consisted of four layers including the target layer, the factor layer, the index layer and the criterion layer, thus forming a model tree based on their subordinate relation-ships. The GDAHP method was employed to determine the weights of constituting factors of each layer in the evaluation model, and the fuzzy method was used to establish the factors remark sets of the criterion layer, thus the single-layer evaluation and comprehensive evaluation of urban lake landscape quality was carried out. Quality evaluation model of urban lake landscape established based on the GDAHP method can provide grounds for planning, design, and renewal of urban lake landscape. This model has been used to evaluate and analyze the artificial lake in People’s Park of Xinxiang City, Henan Province. The results proved that the overall landscape quality of the artificial lake of Peoples Park in Xinxiang city was good.

Biogeographic distribution patterns of algal community in different urban lakes in China: Insights into the dynamics and co-existence

Urban lake ecosystems are significant for social development,but currently we know little about the geographical distribution of algal community in urban lakes at a large-scale.In this study,we investigated the algal community structure in different areas of urban lakes in China and evaluated the influence of water quality parameters and geographical location on the algal community.The results showed that obvious differences in water quality and algal communities were observed among urban lakes in different geographical areas.Chlorophyta was the dominant phylum,followed by cyanobacteria in all areas.The network analysis indicated that algal community composition in urban lakes of the western and southern area showed more variations than the eastern and northern areas,respectively.Redundancy analysis and structural equation model revealed that nutrients and p H were dominant environmental factors that affected the algal community,and they showed higher influence than that of iron,manganese and COD Mn concentration.Importantly,algal community and density exhibited longitude and latitude relationship.In general,these results provided an ecological insight into large-scale geographical distributions of algal community in urban lakes,thereby having potential applications for management of the lakes.

Temporal patterns of algae in different urban lakes and their correlations with environmental variables in Xi’an,China

Urban lakes were critical in aquatic ecology environments,but how environmental factors affected the distribution and change characteristics of algal communities in urban lakes of Xi’an city was not clearly.Here,we investigated the algal community structure of six urban lakes in Xi’an and evaluated the effects of water quality parameters on algae.The results indicated that the significant differences on physicochemical parameters existed in different urban lakes.The maximum concentration of total phosphorus in urban lakes was(0.18±0.01)mg/L and there was a phenomenon of phosphorus limitation.In addition,51 genera of algae were identified and Chlorella sp.was the dominant algal species,which was affiliated with Chlorophyta.Network analysis elucidated that each lake had a unique algal community network and the positive correlation was dominant in the interaction between algae species,illustrating that mature microbial communities existed or occupied similar niches.Redundancy analysis illustrated that environmental factors explained 47.35% variance of algal species-water quality correlation collectively,indicating that water quality conditions had a significant influence on the temporal variations of algae.Structural equation model further verified that algal community structure was directly or indirectly regulated by different water quality conditions.Our study shows that temporal patterns of algal communities can reveal the dynamics and interactions of different urban ecosystem types,providing a theoretical basis for assessing eutrophication levels and for water quality management.

Effects of seasonal climatic variability on several toxic contaminants in urban lakes: Implications for the impacts of climate change

Climate change is supposed to have influences on water quality and ecosystem. However, only few studies have assessed the effect of climate change on environmental toxic contaminants in urban lakes. In this research, response of several toxic contaminants in twelve urban lakes in Beijing, China, to the seasonal variations in climatic factors was studied. Fluorides, volatile phenols, arsenic, selenium, and other water quality parameters were analyzed monthly from2009 to 2012. Multivariate statistical methods including principle component analysis, cluster analysis, and multiple regression analysis were performed to study the relationship between contaminants and climatic factors including temperature, precipitation, wind speed, and sunshine duration. Fluoride and arsenic concentrations in most urban lakes exhibited a significant positive correlation with temperature/precipitation, which is mainly caused by rainfall induced diffuse pollution. A negative correlation was observed between volatile phenols and temperature/precipitation, and this could be explained by their enhanced volatilization and biodegradation rates caused by higher temperature. Selenium did not show a significant response to climatic factor variations, which was attributed to low selenium contents in the lakes and soils. Moreover, the response degrees of contaminants to climatic variations differ among lakes with different contamination levels. On average, temperature/precipitation contributed to 8%, 15%, and 12% of the variations in volatile phenols, arsenic, and fluorides,respectively. Beijing is undergoing increased temperature and heavy rainfall frequency during the past five decades. This study suggests that water quality related to fluoride and arsenic concentrations of most urban lakes in Beijing is becoming worse under this climate change trend.

Long-term phosphorus reduction and phytoplankton responses in an urban lake(USA)

Eutrophication is one of the primary factors causing harmful cyanobacteria blooms in freshwater lakes.This study investigated the long-term changes in water quality and summer phytoplankton assemblages in Oswego Lake,OR,USA,in relation to phosphorus reduction through hypolimnetic aeration and alum applications.Both water quality and phytoplankton assemblages were sampled biweekly during the summers from 2001 to 2013.The concentrations of total phosphorus,soluble reactive phosphorus,and total nitrogen decreased 66%,93%and 31%,respectively,in response to the hypolimnetic aeration and alum treatments since 2005.Summer phytoplankton assemblages showed a 62%reduction of cyanobacteria biovolume and a shift from cyanobacteria dominance(2001–2005)to diatom and chlorophyte dominance(2006–2013).Cluster analysis identified four statistically different groups of summer phytoplankton assemblages(denoted Groups 1–4).Nonmetric multidimensional scaling analysis indicated that the four groups were associated with different water quality conditions.Group 1 occurred prior to hypolimnetic aeration and was primarily comprised of cyanobacteria,associated with water conditions of high nutrients and high primary production.Group 2,dominated by cyanobacteria and chlorophytes,occurred between hypolimnetic aeration and alum surface application.Group 3 was dominated by diatoms and occurred after alum surface application.Group 4 included R-strategist phytoplankton that quickly respond to environmental changes and occurred in the years following alum injection,drawdown,and inflow alum treatment.Both Group 3 and 4 were associated with reduced nutrients in the lake.We conclude that these lake management practices had strong effects on both production and community compositions of phytoplankton,and advocate for future studies on large-scale climate impacts on lake ecosystems and to identify corresponding best management practices.

Research review on the treatment of urban landscape lakes

This paper summarizes the treatment experience of eutrophication by domestic and foreign scholars. At the same time, it summarizes the basic methods to govern lakes; Based on this, we advance the basic principles of urban landscape lakes: At first, we must fully investigate lake pollution source, evaluate its pollution ecological risk; Secondly we should put forward possible measures and choose the scheme for implementation, and finally complete the real-time dynamic monitoring, establish long-term supporting policies and treatment mechanism, to ensure that the pollution of lake continues to develop in the direction of health.

Construction of Eco-livable Communities in the New Urbanization:A Case Study of Zhangzhou Green Lake Eco-park

Taking the construction of Green Lake Eco-park for example, this paper introduced the achievements and experience of this project in rural land expropriation, ecological conservation, humanistic development, and commercial development via field investigation, literature consultation and resident interview, and also problems in the current construction. Then suggestions were put forward to provide references for the further improvement of the Green Lake Eco-park.

基于MLR与ARDL的城市湖泊溶解氧浓度模拟

开展城市湖泊溶解氧模拟研究,对促进湖泊水质模拟研究的进展具有重要作用。选取近扬州市中心附近的一个城市湖泊作为研究的特定区域,利用2020年溶解氧、蓝绿藻浓度、水温、电导率、pH观测结果,构建多元线性回归模型和自回归分布滞后模型,对2020年(2020-01-01至2020-12-31)和该年各季度的溶解氧观测序列值进行模拟,结果表明:前者模拟精度相对较低,后者的模拟精度较高,后者对不同时段溶解氧模拟结果的决定系数R^(2)在0.75~0.99;2种模型对湖泊溶解氧的模拟均有较好的适用性,其中,自回归分布滞后模型对时段变化溶解氧序列模拟的适用性更好。

Review of Restoration Technology and Multi-environmental Factors Analysis of West Lake Ecosystem in Hangzhou City

The urban lake ecosystem has the characteristics of long-term,complex and comprehensive in its ecological restoration process because it is related to social and economic activities at multiple levels.Located in Hangzhou City,China,the West Lake is a national-level scenic spot and a world heritage cultural landscape.It provides key ecosystem services for the city and has a significant impact on the urban ecological environment and the well-being of citizens.The West Lake has undergone an 1800-year governance process in history,realizing the harmonious coexistence with Hangzhou City.Since modern times,due to the rapid development of urbanization and industrialization,the water quality of the West Lake and its freshwater ecosystem have been greatly damaged.Since 2002,Hangzhou City has achieved the overall restoration of the West Lake ecosystem through a series of measures,such as water diversion projects,dredging projects,and the West Lake comprehensive protection project,and the water environment and lakeshore landscape have been greatly improved.This study analyzed the restoration technology of the West Lake ecosystem from two scales of the watershed and the site and discussed the water ecological governance system of the West Lake in the past 20 years.Through thedata analyses of the West Lake land use,vegetation,TP,TN,NH_(3)-N,COD_(Mn) and other multi-environmental factors,the results showed that the water quality,transparency and eutrophication of the West Lake had been greatly improved.At the same time,the application of large-scale restoration methods and technologies also required long-term observation,and attention should be paid to the proliferation of alien species and the loss of heritage value,so as to further avoid potential ecological risks caused by ecological restoration.

城市微污染内湖整治技术研究——以深圳市燕栖湖水系为例

深圳市燕栖湖水系是典型的城市内湖,在微污染状态下,燕栖湖水系主要存在有机污染物超标、水体感官效果差、水动力不足和水生态不完善的问题。为了提升周边居民的幸福感,通过控源截污、底泥清淤、水面拦渣、强化循环、生态重建的系统工程措施,对其进行了水环境综合整治。整治后,湖泊水环境质量由微污染状态稳定提升至《地表水环境质量标准》(GB 3838—2002)中Ⅳ类水标准,BOD5和氨氮质量浓度分别稳定在6 mg/L和0.32 mg/L以内。

Numerical Studies on Urban Heat Island Associated with Urbanization in Yangtze Delta Region

おhe impact of modifications of the surface characteristics on local climate is simulated with a numerical mesoscale model in the Yangtze delta region, east of China. The simulated reference case with the current surface properties shows that there is urban heat island in Shanghai city which is located in the center of this region. The modifications of surface characteristics due to the urbanization around Shanghai will lead to the change of local air circulation and redistribution of surface temperature. Simulation for this case shows that the urbanization around Shanghai has little effect on Shanghai, but will extend the area of heat island. Another case is assumed that the area of grassland is kept as 50% while the urban areas are extended. Compared with the case of pure urbanization, the maximum reduction of surface air temperature is 2.0oC in the daytime and 2.3oC at night.

面向水质目标管理的城镇河湖排口雨水径流控制方法与技术

为解决城镇雨水径流管理与市河湖水环境衔接不紧密、雨水径流管理目标设置缺乏依据、水体雨季污染和部分水体返黑返臭等系列问题,构建了面向城镇河湖水体水质目标的雨水径流控制整装成套技术体系,并基于雨期、非雨期不同阶段重点分别提出了技术体系中雨水径流控制方案的相应工艺选择,克服传统快速净化技术处理效果不佳以及高效处理工艺在雨期、非雨期运维不稳定的问题,为实现城镇雨水径流快速净化及河湖水体高品质长效运行提供了科学支撑.

城市新区极端雨洪汇流淹没特性与致灾机理调查研究——以郑州“7.20”特大暴雨(郑东新区)为例

近年来全球极端暴雨发生的可能性与不确定性提高,增加了城市遭遇特大洪涝灾害的风险。城市雨洪与河道洪水有显著差异,灾后雨洪信息快速采集与调研对认清雨洪特性与致灾机理尤显重要。本文以郑州2021年“7.20”特大暴雨为例,结合郑东新区地理与社会环境特点,采用野外调查测量、口述记录、多源数据分析、数值模拟对比相结合的方法开展了城市雨洪汇流淹没特性及致灾机理的调查研究。针对城市雨洪洪痕特征,拟定调查基本方法与适宜工作程序,根据调查区93处洪痕数据绘制了区域雨洪淹没分布图,分析了城市雨洪峰值水位分布特征及调查区汇流特性,探索了道路雨洪汇流流速及行洪道路阻力参数的确定方法。研究表明,城市雨洪地表主要泄流通道是街区道路,汇流方向受连续阻水、导水建筑与路网布局影响,雨洪淹没深度分布与下垫面条件和雨洪汇流特性有关。致灾机理研究分析表明,极端暴雨汇流远超城市排水管网泄流能力,雨洪选择阻力小的街道快速行洪,街道交汇处壅阻引起局部积水严重,这是极端暴雨致灾的直接诱因;而城市新区水系泄洪排涝关系不协调以及清障不力,导致城区河流行洪不畅,干支流异常高水位的顶托,严重降低了管网排涝功能,则是城市雨洪严重积涝致灾的深层原因。研究成果可为城市雨洪调查标准方法的建立与城市新区防洪排涝体系规划提供技术参考。

鄂州青天湖水生态修复方案比选

由于水产养殖及围垦管理不当,鄂州市青天湖水生态环境遭到严重破坏,导致湖泊生物多样性急剧下降,水质严重降低,极大减弱了其天然调协作用与纳污自净能力,对当地居民健康安全形成较大威胁。为了增强青天湖水系排涝能力,匹配城市规划对其功能定位,改善湖泊水生态环境迫在眉睫。本文以青天湖水系综合治理工程为例,对其水生态修复方案展开分析与研究。

基于鸟类生境需求的城市湖岸带设计与修复评估——以梁平双桂湖为例

过度开发和休闲游憩等人类干扰导致湖岸带生境的均质化和退化,影响鸟类生存并制约湖泊湿地的生态服务功能。文章以重庆市梁平区双桂湖国家湿地公园为案例,对2019年实施“环境-生物-结构”协同设计的湖岸带修复工程4年后的鸟类群落及生境进行调查,结合生境制图法量化生境特征。结果表明:双桂湖湖岸带共有鸟类49种、实验区45种、对照区22种;实验区鸟类香农-威纳指数(北岸2.665、西岸2.984)高于东岸对照区(2.563),其中,西岸新增小微湿地面积较北岸更多,水鸟种类及其种群数量增加更为显著。鸟类多样性与生境多样性、鸟类数量与生境丰富度之间呈显著正相关关系(P<0.01)。综上可知,修复工程有效促进了鸟类生境单元多样性的增加;构建湖岸带小微湿地和“林-草-湿”复合生境格局能使生境异质性和鸟类多样性得到持续提升。