基于混合指标值TODIM方法的东营市生态系统健康评价

城市生态系统健康评价是城市可持续发展以及城市生态文明建设的需要。在当今各种"城市病"频发的背景下,研究城市生态系统健康水平,不仅有利于协调城市发展与城市生态系统健康之间的矛盾,而且对于指导城市建设规划编制,监控城市生态环境的可持续发展具有重要的现实意义。鉴于此,论文在原有的城市生态系统健康评价指标的基础上,通过基于混合指标值的TODIM方法评价东营市2007—2013年间的城市生态系统健康状况,并分析活力、组成结构、恢复力、维持生态系统服务功能以及生态系统认知的构成指标对城市生态系统健康状况的影响。为了避免主观判断对城市生态系统健康评价的不确定性,文章采用兼顾客观信息和主观信息的组合权重赋权法确定各个指标的权重;根据东营市城市生态系统健康评价指标的特性和数据特点,建立了混合多属性决策TODIM方法的数学模型;采用扩展的TODIM方法对东营市城市生态系统健康状况进行评价,并分析了各个指标在城市生态发展过程中的作用。研究表明:(1)东营市的城市生态系统健康状况一直向好,由脆弱状态逐渐过渡到亚健康状态,但是生态状况仍然不容乐观,距离健康状态仍有较大的差距;(2)环保投入力度不足、污染物排放量增加、产业结构仍不完善、建成区人口密度过高等成为制约东营市城市生态系统健康发展的突出问题。文章提出了相应的对策建议,以促进城市生态系统的健康发展。     

Integrating channel design and assessment methods based on sediment transport capacity in gravel bed streams

Natural channel design (NCD) and analytical channel design (ACD) are two competing approaches to stable channel design that share fundamental similarities in accounting for sediment transport processes with designs based on hybrid fluvial geomorphology and hydraulic engineering methods. In this paper, we highlight the linkage between ACD's capacity/supply ratio (CSR) and NCD's sediment capacity models (FLOWSED/POWERSED), illustrating how ACD and NCD have reached a point of convergent evolution within the stream restoration toolbox. We modified an existing CSR analytical spreadsheet tool which enabled us to predict relative channel stability using both conventional bed load transport equations and regional sediment regression curves. The stable channel design solutions based on measured data most closely matched the Parker (ACD) and/or Pagosa good/fair (NCD) relationships, which also showed the greatest CSR sensitivity in response to channel alterations. We found that CSR differences among the transport relationships became more extreme the further the design width deviated from the supply reach, suggesting that a stable upstream supply reach may serve as the best design analog. With this paper, we take a step toward resolving lingering controversy in the field of stream restoration, advancing the science and practice by reconciling key differences between ACD and NCD in the context of reach scale morphodynamics.     

长江中游城市群空间联系研究

基于城市流强度模型和城市间相互作用模型,以长江中游城市群27个地级市为研究对象,分析了城市群内的城市辐射能力及其内在的经济联系。结果表明:(1)长江中游城市群整体集聚和辐射能力较弱,区域内中低级城市流强度的城市占多数;(2)城市群内第二、三产业辐射能力存在较大差异,第二产业呈现出较强的辐射能力,而第三产业辐射能力较弱,并且其空间分布相对较为分散;(3)区域中心城市的核心带动作用总体较弱,辐射范围和辐射强度都有待加强;(4)长江中游城市群内城市间空间联系不够紧密,且联系程度空间差异较大。省际城市之间联系贫乏,城市间尚未形成联系紧密的辐射网络。     

Mitigating urban sprawl effects: a collaborative tree and shade intervention in Phoenix,Arizona, USA

Communities in Phoenix are confronted with numerous challenges that adversely affect human health and safety, with disproportionate impacts on low-income communities. While some challenges are being addressed at the city level, new alliances at the neighbourhood level are initiating community development programmes and projects. This article reports on an intervention study carried out in collaboration with community representatives, city staff, and non-profit organisations to mitigate adverse effects of urban sprawl in the Sky Harbour Neighbourhood in Phoenix. Participatory research was conducted to design and test a tree and shade intervention. Challenges associated with navigating community desires and broader principles of sustainable development are discussed. The study offers a replicable and adaptable intervention research design aimed at empowering communities to meet urban challenges.     

Using the land transformation model to forecast vacant land

Growing or shrinking cities can experience increases in vacant land. As urban populations and boundaries fluctuate, holes can open in once tight urban areas. Many cities chase growth-oriented approaches to dealing with vacancies. It is critical to understand land-use alteration to accurately predict transformations of physical change in order to make better informed decisions about this phenomenon. This research utilizes the land transformation model (LTM), an artificial neural networking mechanism in Geographic Information Systems, to forecast vacant land. Variable influence on vacant land prediction and accuracy of the LTM is assessed by comparing input factors and patterns, using time-series data from 1990 to 2010 in Fort Worth, Texas, USA. Results indicate that the LTM can be useful in simulating vacant land-use changes but more precise mechanisms are necessary to increase accuracy. This will allow for more proactive decisions to better regulate the process of urban decline and regeneration.     

Linking Nitrogen Export to Landscape Heterogeneity: The Role of Infrastructure and Storm Flows in a Mediterranean Urban System

Urban ecosystems are often sources of nonpoint source (NPS) nitrogen (N) pollution to aquatic ecosystems. However, N export from urban watersheds is highly variable. Examples of densely urbanized watersheds are not well studied, and these may have comparatively low export rates. Commonly used metrics of landscape heterogeneity may obscure our ability to discern relationships among landscape characteristics that can explain these lower export rates. We expected that differences not often captured by these metrics in the relative cover of vegetation, structures, and impervious surfaces would better explain observed variation in N export. We examined these relationships during storms in residential watersheds. Contrary to expectations, land cover did not directly predict variation in N or water export. Instead, N export was strongly linked to drainage infrastructure density. Our research highlights the role of fine‐scaled landscape attributes, mainly infrastructure, in explaining patterns of N export from densely urbanized watersheds. Changes to hydrologic flow paths by infrastructure explained more variation in N export than land cover. Our findings support further development of landscape ecological models of urban N export that focus on hydrologic modification by infrastructure rather than traditional landscape measures such as land use, as indicators for evaluating patterns of NPS nitrogen pollution in densely urbanized watersheds.     

长江经济带城市对外服务能力时空演变分析

基于城市流强度模型测算2000年以来长江经济带126个地级以上城市在全国范围内的对外服务能力,进而采用改良锡尔系数、马尔可夫链和ESDA方法对城市对外服务能力的时空演变特征进行探讨。结果表明:研究时段内长江经济带各市城市流强度都有显著提升,但区域间的非均衡现象明显,城市对外服务能力呈现出由东部向西部的梯度递减;省内差异对城市对外服务能力的差异贡献率最高,是空间尺度差异的主要来源;对外服务能力存在明显的俱乐部趋同现象和空间自相关性,对外服务能力相似的区域聚集分布,东、中、西部分别形成长三角、武汉-长沙、成渝等对外服务区域中心;时空演变表现出阶段性特征,经历由极化向均衡的转变。最后指出多中心发展和寻找新增长点应成为长江经济带城市对外服务能力提升的方向。     

河道沉积物中磷的分布、吸附及释放规律研究

为科学评价磷在河道沉积物中的环境行为,在模拟条件下研究了上海市进木港和苏州河沉积物中磷的分布形态、吸附特征及释放规律.结果表明:(1)2种沉积物中碎屑钙磷(De-P)浓度最高,闭蓄态磷(Oc-P)次之,其他形态磷浓度相对较低,而活性磷中以铁磷(Fe-P)为主；(2)2种沉积物对磷的吸附均符合线性方程,在4.0h时基本达...     

面向城市水系环境需水的再生水空间配置——以深圳市宝安区为例

以深圳市宝安区为例,探讨以再生水满足城市水系环境需水的方法.应用一维恒定与非恒定水质模型计算了4种补水水质方案下该区10条主要河流的环境需水量,从水量平衡角度提出全区再生水BOD5的平均值,并进一步分析了补水水质与河流环境需水量的关系.结合该区水系与污水处理系统空间位置,提出3种再生水的空间配置方法.结果表明:茅洲河和...     

基于快速聚类方法分析常州市区PM2.5的统计特性

运用统计方法研究常州市区2013~2014年6个国控点六项基本污染物(SO_2、NO_2、CO、O_3、PM_(2.5)和PM_(10))月平均浓度变化,结果表明,除O_3外,其它五项污染物月平均浓度夏季较低冬季较高.颗粒物与风速之间的关系为PM_(2.5)浓度随风速的升高一直降低,PM_(10)随风速的升高浓度先降低后升高.采用快速聚类分析(k-means)并运用SWV和DIV指数对六项基本污染物进行分类,得到4个样本分类.与依据颗粒物化学成分或粒径谱对PM进行源解析方法不同,本研究更多是从PM_(2.5)与其它污染物相关关系以及污染程度等角度按照欧式距离进行分类.不同类中PM_(2.5)来源明显不同,类1中PM_(2.5)与化石燃料燃烧排放密切相关,类2与O_3密切相关,类3与城市不完全燃烧排放、区域灰霾污染密切相关,类4可以归类于城市"背景"类.快速聚类分析结果也表明常州市区PM_(2.5)有着复杂的来源.