基于门槛时间划定的天津市半城市化区县发展历程及机制 研究

作为京津冀典型特大城市之一,天 津市半城市化区县的发展与城镇化驱动机制 在京津冀都市圈有较强的代表性,且与长三 角珠三角地区的发展特征有巨大差异。本文 在既有研究的基础上优化指标体系,提出门 槛时间划定方法和发展模式分析方法,并将 其应用于天津市半城市化区县。分析结果显 示：天津市半城市化空间扩张经历了轴向缓 慢发展、圈层+轴向拓展、中郊蔓延以及远郊 辐射四大发展阶段;近远郊发展模式差异较 大,其中近郊以土地—综合—人口的快速迭 代增长模式为主,中远郊则以土地—人口（经 济）的缓慢波动发展模式为主。最后,结合分 析结果和实际发展路径对其发展机制与治理 瓶颈进行分析。     

Barriers and strategies for dry sanitation in large-scale and urban settings

Centralized waterborne sanitation faces serious social, economic and environmental sustainability challenges. Dry sanitation (DS) may ease some of those, but it is not known whether DS can be a viable solution at large scales and in urban settings. We assessed DS viability in a broad range of large scale and urban contexts in Mexico. Here, we synthesize the operational and structural barriers encountered across a diversity of sites, provide an understanding of how and why those barriers arose and propose a set of strategies through which those barriers can be addressed. We include reference to other large-scale and urban experiences outside Mexico.     

Major nutrient balances in small-scale vegetable farming systems in peri-urban areas in China

Balances of major nutrients such as nitrogen (N), phosphorus (P), and potassium (K) in small-scale farming systems are of critical importance to nutrient management and sustainable agricultural development. Mass balances of N, P, and K and some of their influencing factors were studied for two years from July 2003 to July 2005 on small-scale vegetable-farming systems in two contrasting peri-urban areas (Nanjing and Wuxi) of the Yangtze river delta region of China. This balance approach considered organic fertilizer inputs (cow manure, pig manure, and human biosolids), inorganic fertilizer inputs (urea, composite fertilizer, and phosphates), irrigation water, and atmospheric deposition; and considered outputs by vegetables. Input via organic fertilizers was significant for all element balances in the Nanjing area. Inorganic and organic fertilizer, particularly inorganic fertilizer, contributed major nutrient inputs to the system in the Wuxi area. Compared with nutrient output by vegetables, there were significant surpluses of N and P on two vegetable farm systems. Furthermore, N surplus in the Nanjing area was higher than that in the Wuxi area with an inverse relationship to P surplus. In contrast, the general trend of K balances was negative on both sites; hence, the nutrient use efficiency was significantly lower for N and P than K. The nutrient imbalance may be attributed to the differences between fertilizer types and management modes driven by social economic status differences among farmer households. The large N and P net excess creates an environmental threat because of potential losses to ground or surface waters, whereas negative K balance creates soil fertility risks. The results highlight researchers’ and farmers’ need to develop rational fertilization technology to optimize nutrient management on vegetable farmlands to promote sustainable agricultural development in peri-urban areas.     

Contextualizing transport infrastructure and services in Ghanaian peri-urbanism

This study interrogates the demand and supply of transport infrastructure and services in peri-urban areas of Sunyani Municipality in Ghana. Structured one-on-one interviews were conducted with 100 households across three peri-urban communities in Sunyani (Abesim-Kyidom, Asuakwaa and Adomako). Findings revealed that a majority of peri-urban households (84%) in the study communities who commute daily to and from the city centre are faced with poor transport infrastructure (e.g. poor conditions of road) and unreliable services (e.g. unregulated public transport). Inadequate investment in transport infrastructure and services by the Ghanaian government, the limited activity locations in peri-urban areas, and the concentration of activity locations at the city centre were identified to be contributing to the poor state of transport infrastructure and services in the case study communities. Policy recommendations to improve the situation are further proffered.     

User satisfaction in large-scale,urban dry sanitationprograms in Mexico

Dry sanitation (DS) may be part of the solution to water scarcity, water quality deterioration and lack of resources to provide or maintain waterborne sewage systems. However, the worldwide paucity of large-scale, urban case studies makes assessment of DS as a potential urban water management strategy difficult. Urban DS viability depends in part on urban users' satisfaction with dry toilets (DTs) and whether they would accept them as long-term sanitation options. We analyze user acceptance and satisfaction with DS in five Mexican cities. When toilets functioned well (four out of five sites), users were highly satisfied. Similar levels of satisfaction were found under conditions of different DT models, types of DS program and income-level of the population. User motivation, choice and adequate support services were positively associated with satisfaction. Incentives such as indoor, aesthetic DTs, maintenance and end-product collection services, as well as higher water supply pricing, would encourage people to accept DS as a long-term option. We discuss reasons for dissatisfaction at one of the study sites.     

基于主动性战略的城郊农业用地控制研究* ——以宝鸡市渭河南部台塬区生态建设规划为例

城市化的快速发展使城郊农业用地面临着被蚕食的巨大威胁。城郊农业用地一直处于被动适应的状态,如何将被动引向主动对自然环境保护与城市用地控制十分重要。主动性战略是促进城郊农业自我维护的基本思想战略,通过对主动性战略方针的解析,结合宝鸡市渭河南部台塬区生态建设规划实践,提出了农业用地主动性规划的思路与方法:构建生态网络空间结构;协调发展城乡用地布局;发展多元绿色产业。同时,在管理控制上,将生态原则纳入法律体系,强调城乡各部门的协作管理。     

Cultural Landscape: Stone Towers on Mount Etna

This work reports the findings of an investigation by Etna’s local councils whose publicly owned land has high concentrations of particularly significant towers. The towers are original stone constructions, presumed to have been built between the end of the 1700s and the beginning of the 1900s and so are unrelated to medieval towers, emblems of ancient yet sophisticated building techniques and located in numerous agricultural areas on the slopes of Mount Etna, Europe’s most active volcano. They are built out of the stones removed from the agricultural land of the soils regenerated from the lava flows wedged in between basalt outcrops. Together with other stone artefacts, they form part of a renewable heritage of great value both for their recognised role in maintaining biodiversity as well as for their cultural, landscape and historical significance. These constructions are in a state of extreme abandonment or are gradually disappearing due to the loss of agriculture or the changeover of agricultural land into building sites. The enquiry used historical documents, censuses of tower characteristics and field data. Four council zones were identified and in each only clearly identifiable towers were considered (total: 19). The field data highlighted considerable architectural complexity in their proportions and construction techniques. Their historico-cultural-landscape validity was confirmed as was the necessity of appropriate and urgent state intervention.     

小尺度土壤养分的空间变异及其影响因素探讨--以江苏省无锡市典型城乡交错区为例

以江苏省无锡市城乡交错区为例,在8km2范围内,采集102个土壤表层样,利用地统计学和G IS相结合的方法,研究了土壤全量和速效氮、磷、钾的空间变异特征,并对其影响因素进行了探讨。结果表明土壤养分空间变异程度从大到小依次为:土壤全氮>土壤全磷>土壤速效磷>土壤速效氮>土壤速效钾>土壤全钾。土壤全氮空间变异受到土壤类型的影响,土壤全磷的空间变异与居民点分布有关,土壤全钾空间变异与土壤粘粒关系最密切。土壤全量养分和相应的速效养分具有显著相关关系,在空间分布上,也分别存在不同程度的相似性。同时土壤全磷和土壤速效养分受土地利用影响也较大。研究还表明,城乡交错区土壤氮、磷流失风险增加,需要实施有效措施控制氮、磷肥料的过度施用。     

Gaborone

The city of Gaborone, like Botswana, the nation of which it is capital, is extraordinary in African terms. Here is a city lacking in mass poverty, extensive squatter settlements or recurrent civil strife: for all appearances, an orderly, affluent urban area. For these reasons, it is an important example of how planning authorities in a developing nation have managed urban growth. Gaborone has had opportunities other African cities have not. Thus it invites questions as to how these have been managed and expressed. A key issue which emerges is the co-location of informal, traditional and modern forms of land allocation both within Gaborone City and the peri-urban regions with which it is increasingly connected. This throws up a number of issues, including the inconsistent way in which planning authorities have managed this ‘balancing act’.     

Energy assessment of peri-urban horticulture and its uncertainty: Case study for Bogota,Colombia

Scarce information is available about the energy use pattern of horticultural commodities in general and more specifically for peri-urban horticulture. Peri-urban horticulture in the outskirts of Bogota is an important source of vegetables for Colombia's capital city. Based on detailed follow-ups and periodic field measurements an output–input energy balance was performed with the main objective to study the energy use efficiency of those systems. An uncertainty analysis on the input factors and on the energy equivalents was then applied. Over a measurement period of 18-month, the energy use for coriander, lettuce, radish and spinach was investigated, respectively 12.1, 18.8, 6.6 and 10.7 GJ ha⁻¹ were consumed in these cropping systems. Negative balances were observed for all species exception made for spinach where an output:input ratio of 1.16 was found. The two-way uncertainty analysis showed the highest uncertainty for N-based fertilization while no significant effect was observed for seeds in direct sowing crops. Sustainability of peri-urban horticulture around Bogota is compromised not only because of the city expansion but also due to its inefficient energy use. Technical improvements are required to ensure the environmental subsistence of this important sector for the metropolitan area of the city.