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151.
This paper presents evidence that water restrictions in suburbanizing eastern Massachusetts towns are becoming more common, controlling for climate. We then assess the relationship between these suburban droughts and residential development. Focusing on the suburbs of Boston, seven towns independent of the Boston water supply system were selected to represent differing levels of sprawl-style growth. Water restrictions are becoming more frequent in all of the towns studied, and models demonstrate that restrictions are increasing in duration, independent of climate. Interviews suggest that residential development is playing a central role in this increasing sensitivity to suburban drought, though other factors are also important. Long-term planning and integration of land-use planning and water management emerged as two key paths for attenuating the impacts of development. 相似文献
152.
李衍 《中国特种设备安全》2014,(3):43-47
本文介绍应用相控阵技术结合配有编码动作的机械装置,对插入式管座焊缝从接管内侧用线阵探头进行超声检测的方法。建立实验模型,可为声柬全覆盖所必须考虑的物理参数,提供验证数据。建模和实测结果表明:利用声线跟踪法,扫查布置图(Scanplan)能提供所需覆盖范围的适当显示。当从接管内表面进行扫查时,用于引导探头扫查动作的机械装置往往可设计得减少复杂性。本文所述方法可望为承压设备结构较复杂的管座焊缝,实施超声相控阵检测(PAUT)符合ASME最新版要求提供有用借鉴。 相似文献
153.
Penov I 《Environmental management》2004,34(2):304-313
The amount of water Bulgaria uses for irrigation sharply declined during the transition. Large sections of the existing irrigation systems were abandoned, and those still in use are hardly maintained. Crops such as wheat and barley have replaced more water-intensive crops, such as vegetables, rice, and maize. This problem has an impact on the future development of agriculture and the allocation of the countrys water resources. The central argument is that land fragmentation in the wake of decollectivization and restitution contributes to the irrigation systems abandonment. This article focuses on the institutional factors involved, but also considers additional factors that might have influenced the process. Further, it examines the causes driving these changes and analyzes their effect on irrigation. It is based on a review of the relevant legislation as well as fieldwork in 17 villages located in the Plovdiv region of Bulgaria. The article concludes that institutional settings, in addition to changes in large-scale market forces and the state enforcement mechanism, have contributed to the irrigation decline in Bulgaria.Published online
Note: This version was published online in June 2005 with the cover date of August 2004. 相似文献
154.
内蒙古自治区农牧业自然灾害特征分析 总被引:4,自引:0,他引:4
本文采用近50年的农牧业气象灾害数据资料和近15年的农牧业病虫害及灾情数据资料,结合实地调查,对内蒙古自治区主要农牧业自然灾害的发生特征和平均状况进行了分析.研究表明:近50年本区农业自然灾害有加重趋势;从年际来看,旱灾、病虫鼠害、风灾较稳定频发,水灾、冻灾、火灾年际变率大;旱灾、冻灾、火灾、风灾冬春多发;多种灾害链发等.在此基础上结合自然条件探究原因,提出了一些防灾减灾的建议. 相似文献
155.
In order to balance pressures for land-use development with protection of wetland resources, artificial wetlands have been
constructed in an effort to replace lost ecosystems. Despite its regulatory appeal and prominent role in current mitigation
strategies, it is unclear whether or not created systems actually compensate for lost wetland resources. Mitigation predictions
that rely on artificial wetlands must be analyzed critically in terms of their efficacy. Destruction of wetlands due to burial
by coal fly ash at a municipal landfill in Danvers, Massachusetts, USA, provided an opportunity to compare resulting growth
of created cattail (Typha) marshes with natural wetland areas. Once the appropriate cattail species was identified for growth under disturbed landfill
conditions, two types of artificial wetlands were constructed. The two systems differed in their hydrologic attributes: while
one had a surface water flow characteristic of most cattail wetlands, the second system mimicked soil and water conditions
found in naturally occurring floating cattail marshes. Comparison of plant growth measurements for two years from the artificial
systems with published values for natural cattail marshes revealed similar structure and growth patterns. Experiments are
now in progress to investigate the ability of created cattail marshes to remove and accumulate heavy metals from polluted
landfill leachate. Research of the type reported here must be pursued aggressively in order to document the performance of
artificial wetlands in terms of plant structure and wetland functions. Such research should allow us to start to evaluate
whether artificial systems actually compensate for lost wetlands by performing similar functions and providing the concomitant
public benefits. 相似文献
156.
本文论述了内蒙古呼伦贝尔盟主要野生药用植物分布区域及其生态环境特点,并对北黄芪等15种药用植物的生态生物学特征、区系地理成分和药用价值进行了重点描述,对如何保护与合理利用药用植物资源提出了建议。 相似文献
157.
Hugh Clout 《Journal of Environmental Planning and Management》1984,27(2):84-92
Over the past thirty years Bordeaux's politicians and planners have played critical roles in both changing and conserving the inner environments of one of France's most attractive provincial cities. A succession of urban policies has been implemented to attempt to halt depopulation, economic decline and environmental degradation in the inner city. These policies reflect changing emphasis in national planning for urban areas and have ranged from slum clearance and total renovation in the Mériadeck district, to a recent more socially aware set of approaches that attempt to rehabilitate inner‐city housing and promote neighbourhood well‐being in the district of Saint Michel. Investment in architectural conservation continues apace and both private and public capital is being directed to improving housing stock in the inner city. Attempts to revitalise economic activities have achieved modest success but more socially orientated policies prove difficult to implement. 相似文献
158.
159.
东部沿海地区农户非农就业对农地租赁行为的影响研究 总被引:4,自引:1,他引:3
非农就业后农户如何利用农地资源成为决定粮食安全与农民增收的关键。基于生产决策理论剖析了不同情境下农户非农就业对农地租赁行为的影响,并采用东部沿海地区599个农户调查数据进行了检验。结果表明:①有剩余劳动力与无剩余劳动力情景,农户非农就业对农地租赁行为的影响并不一致;②非农就业改变家庭要素禀赋结构与劳动力相对报酬,进而影响农地租赁行为;③东部沿海地区农地租赁行为响应是非农就业特征与外部环境综合作用的结果,其中非农就业规模、非农就业区位、非农就业逆向淘汰程度与农地租出行为呈正相关关系,从事第二产业的农户倾向于租出农地。非农就业规模的农地租赁行为响应存在门槛效应,而非农就业类型的总体影响较小。 相似文献
160.