Problems of Rural Migrant Workers and Policies in the New Period of Urbanization

The huge migration of rural workers has new characteristics such as the bad order, high degree of concentration, low level of collective action, marginality in social status, unfair treatment, difficult integration of the new generation, and the new return trend of rural migrants, which causes ＇urban diseases＇ in China. Countermeasures should be taken to develop medium-sized and small cities, integrate the labor market of the city and countryside, provide necessary public services, social security and vocational training, guide the rural migrant workers to return rationally, and help the new generation live in harmony with urban residents.     

RELATION OF MACROINVERTEBRATE COMMUNITY IMPAIRMENT TO CATCHMENT CHARACTERISTICS IN NEW JERSEY STREAMS1

ABSTRACT: The level of macroinvertebrate community impairment was statistically related to selected basin and water-quality characteristics in New Jersey streams. More than 700 ambient biomonitoring stations were chosen to evaluate potential and known anthropogenic effects. Macroinvertebrate communities were assessed with a modified rapid-bioassessment approach using three impairment ratings (nonimpaired, moderately impaired, and severely impaired). Maximum-likelihood multiple logistic-regression analysis was used to develop equations defining the probability of community impairment above predetermined impairment levels. Seven of the original 140 explanatory variables were highly related to the level of community impairment. Explanatory variables found to be most useful for predicting severe macroinvertebrate community impairment were the amount of urban land and total flow of municipal effluent. Area underlain by the Reading Prong physiographic region and amount of forested land were inversely related to severe impairment. Nonparametric analysis of variance on rank-transformed bioassessment scores was used to evaluate differences in level of impairment among physiographic regions and major drainage areas simultaneously. Rejection of the null hypothesis indicated that the levels of impairment among all six physiographic regions and five major drainage areas were not equal. Physiographic regions located in the less urbanized northwest portion of New Jersey were not significantly different from each other and had the lowest occurrence of severely impaired macroinvertebrate communities. Physiographic regions containing urban centers had a higher probability of exhibiting a severely impaired macroinvertebrate community. Analysis of major drainage areas indicates that levels of impairment in the Atlantic Coastal Rivers drainage area differed significantly from those in the Lower Delaware River drainage area.     

Stream Temperature Surges Under Urbanization and Climate Change: Data,Models, and Responses1

ABSTRACT: Multiple anthropogenic stressors, including increased watershed imperviousness, destruction of the riparian vegetation, increased siltation, and changes in climate, will impact streams over the coming century. These stressors will alter water temperature, thus influencing ecological processes and stream biota. Quantitative tools are needed to predict the magnitude and direction of altered thermal regimes. Here, empirical relationships were derived to complement a simple model of in‐stream temperature [developed by Caissie et al. Canadian Journal of Civil Engineering 25 (1998) 250; Journal of Hydrology 251 (2001) 14], including seasonal temperature shifts linked to land use, and temperature surges linked to localized rainstorms; surges in temperature averaged about 3.5°C and dissipated over about 3 h. These temperature surges occurred frequently at the most urbanized sites (up to 10% of summer days) and could briefly increase maximum temperature by >7°C. The combination of empirical relationships and model show that headwater streams may be more pervasively impacted by urbanization than by climate change, although the two stressors reinforce each other. A profound community shift, from common cold and coolwater species to some of the many warmwater species currently present in smaller numbers, may be expected, as shown by a count of days on which temperature exceeds the “good growth” range for coldwater species.     

自然资源禀赋与城市化水平关系的多尺度考察

通过对单体区域在时间序列上的分析和对多个区域面板数据集综合水平的横向比较，本文在多个尺度上验证了自然资源禀赋在区域城市化过程的“资源诅咒”假说，并且通过在省际层面上建立经济计量模型进行理论检验，也得出“资源诅咒”效应在一定程度上的确存在的结论。文章还分析了城市化过程中自然资源产生限制作用的作用机理。认为这种效应是多种要素综合作用的结果，并提出了相应的政策建议。这项研究在理论上丰富了城市化动力机制和“资源诅咒”假说的研究，在实践上也具有一定的现实意义。     

乌鲁木齐城市化进程与大气污染关系研究

以乌鲁木齐市为研究区,选取乌鲁木齐市2004—2013年11项城市化指标以及3项大气污染指标,得出城市化水平综合指数以及大气污染水平综合指数。将城市化综合水平作为解释变量,SO2、NO2、PM10污染综合指数、大气污染综合指数分别作为被解释变量,分析城市化水平与大气污染状况,分别对其进行二次曲线回归分析以及三次曲线回归分析,得出乌鲁木齐市2004—2013年城市化进程与大气污染之间的演化规律。     

资源型区域中心城市的产业演进与城市化发展——以太原市为例

在经济发展的不同阶段。工业化与城市化之间的关系有不同的表现。其产业演进与城市化发展特征也不相同。本文以山西省会城市——太原市为例。研究了资源型区域中心城市的产业演进与城市化发展。主要思路是：在对产业演进与城市化发展的相关研究成果进行梳理的基础上。分析总结了资源型区域中心城市产业演进与城市化发展的基本规律。以太原为案例研究了不同发展阶段产业演进与城市化发展的特征和机制。并对其未来发展方向进行了讨论。     

河南省农村劳动力转移、第三产业发展与城市化关系分析

有效推进城市化进程是实现城乡协调发展的重要途径。城市化的实质是农村劳动力及其供养人口向非农产业转移并向城市（镇）集聚的过程。在欠发达地区。城市化进程在很大程度上取决于农村剩余劳动力的转移空间．转移空间越大。农村劳动力转移的拉力就越大．城市化进程的速度也就越快。据此。将农村劳动力转移作为城市化的一个主导过程，并基于河南城市化水平较低与第三产业就业比重严重偏低的事实．提出“第三产业内部构成不合理所导致的对农村劳动力转移拉力不足．是制约河南城市化进提的量主要因素”这个假设。通过构建农村劳动力转移模型．对河南农村劳动力转移的影响要素进行定量分析。结果显示该假设是成立的。以此为依据．最后提出河南省通过合理发展第三产业。推进城市化的政策建议。     

南京市快速城市化过程中人均生态足迹的动态变化与预测研究

基于《南京统计年鉴》数据,应用生态足迹分析方法,计算了南京市1992～2002年人均生态足迹、人均生态承载力和生态赤字,并对过去11年生态足迹各项指标及其动态变化进行了分析。结果显示,南京市人均生态足迹明显高于江苏省平均水平,更是高于全国水平的2倍,已超过了2.0 hm2/人的全球生态阈值,人均生态承载力明显偏低,全市生态赤字高达自身面积的20倍,表明南京市资源环境形势不容乐观,区域可持续发展面临严峻挑战。随着城市化、工业化和社会经济的迅速发展,过去11年间南京市呈现人均生态足迹逐年升高、人均生态承载力不断降低的动态趋势。鉴于此,必须实施资源节约高效、生态环境友好、控制人口负荷等重大战略举措,实现快速城市化、工业化背景下的区域可持续发展。其次利用灰色模型预测了2003～2005年的人均生态足迹和生态承载力,预测精度较好。     

珠江三角洲城镇用地扩展的城市化背景研究

在分析珠江三角洲1990～2000年的城镇用地扩展现状的基础上,论文采用城镇用地的综合扩展系数将珠江三角洲划分为强扩展型、弱扩展型和相对稳定型3种变化类型。同时,根据城市化发展阶段的划分和城市化与城镇用地扩展耦合系数的研究,揭示了城镇用地扩展强度与城市化发展水平的关系。最后,进一步从城市化发展的空间格局入手,分析了城镇用地扩展的特征。研究表明,1990～2000年珠江三角洲城镇用地的扩展与城市化的发展水平和空间发展格局直接相关。城镇用地的强扩展区除集中在以广州、深圳和珠海为顶点的三角区域内和重要交通轴线两侧外,还表现出以广州、深圳和珠海为核心,向周边地区扩展强度与数量递减的规律。     

MODELING TRANSIENT pH DEPRESSIONS IN COASTAL STREAMS OF BRITISH COLUMBIA USING NEURAL NETWORKS1

ABSTRACT: Transient events in water chemistry in small coastal watersheds, particularly pH depressions, are largely driven by inputs of precipitation. While the response of each watershed depends upon both the nature of the precipitation event and the season of the year, how the response changes over time can provide insight into landscape changes. Neural network models for an urban watershed and a rural‐suburban watershed were developed in an attempt to detect changes in system response resulting from changes in the landscape. Separate models for describing pH depressions for wet season and dry season conditions were developed for a seven year period at each watershed. The neural network models allowed separation of the effects of precipitation variations and changes in watershed response. The ability to detect trends in pH depression magnitudes was improved by analyzing neural network residuals rather than the raw data. Examination of sensitivity plots of the models indicated how the neural networks were affected by different inputs. There were large differences in effects between seasons in the rural‐suburban watershed whereas effects in the urban watershed were consistent between seasons. During the study period, the urban watershed showed no change in pH depression response, while the rural‐suburban watershed showed a significant increase in the magnitude of pH depressions, likely the result of increased urbanization.