942 resultados para Squatter settlements


Relevância:

10.00% 10.00%

Publicador:

Resumo:

The development of infrastructure in major cities often involves tunnelling, which can cause damage to existing structures. Therefore, these projects require a careful prediction of the risk of settlement induced damage. The simplified approach of current methods cannot account for three-dimensional structural aspects of buildings, which can result in an inaccurate evaluation of damage. This paper investigates the effect of the building alignment with the tunnel axis on structural damage. A three-dimensional, phased, fully coupled finite element model with non-linear material properties is used as a tool to perform a parametric study. The model includes the simulation of the tunnel construction process, with the tunnel located adjacent to a masonry building. Three different type of settlements are included (sagging, hogging and a combination of them), with seven different increasing angles of the building with respect to the tunnel axis. The alignment parameter is assessed, based on the maximum occurring crack width, measured in the building. Results show a significant dependency of the final damage on the building and tunnel alignment.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

One of the main causes of failure of historic buildings is represented by the differential settlements of foundations. Finite element analysis provides a useful tool for predicting the consequences of given ground displacements in terms of structural damage and also assesses the need of strengthening techniques. The actual damage classification for buildings subject to settlement bases the assessment of the potential damage on the expected crack pattern of the structure. In this paper, the correlation between the physical description of the damage in terms of crack width and the interpretation of the finite element analysis output is analyzed. Different discrete and continuum crack models are applied to simulate an experiment carried on a scale model of a masonry historical building, the Loggia Palace in Brescia (Italy). Results are discussed and a modified version of the fixed total strain smeared crack model is evaluated, in order to solve the problem related to the calculation of the exact crack width.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Excavation works in urban areas require a preliminary risk damage assessment. In historical cities, the prediction of building response to settlements is necessary to reduce the risk of damage of the architectural heritage. The current method used to predict the building damage due to ground deformations is the Limiting Tensile Strain Method (LTSM). In this approach the building is modelled as an elastic beam subjected to imposed Greenfield settlements and the induced tensile strains are compared with a limit value for the material. These assumptions can lead to a non realistic evaluation of the damage. In this paper, the possibility to apply a settlement risk assessment derived from the seismic vulnerability approach is considered. The parameters that influence the structural response to settlements can be defined through numerical analyses which take into account the nonlinear behaviour of masonry and the soil-structure interaction. The effects of factors like material quality, geometry of the structure, amount of openings, type of foundation or the actual state of preservation can be included in a global vulnerability index, which should indicate the building susceptibility to damage by differential settlements of a given magnitude. Vulnerability curves will represent the expected damage of each vulnerability class of building as a function of the settlement.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Underground constructions in soft ground may lead to settlement damage to existing buildings. In The Netherlands the situation is particularly complex, because of the combination of soft soil, fragile pile foundations and brittle, unreinforced masonry façades. The tunnelling design process in urban areas requires a reliable risk damage assessment. In the engineering practice the current preliminary damage assessment is based on the limiting tensile strain method (LTSM). Essentially this is an uncoupled analysis, in which the building is modelled as an elastic beam subject to imposed Greenfield settlements and the induced tensile strains are compared with a limit value for the material. The soil-structure interaction is included only as a ratio between the soil and the building stiffness. In this paper, a coupled approach is evaluated. The soil-structure interaction in terms of normal and shear behaviour is represented by interface elements and a cracking model for masonry is included. This project aims to improve the existing damage classification system for masonry buildings subjected to tunnel-induced settlement, in order to evaluate the necessity of strengthening techniques or mitigation measures.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Excavation works in urban areas require a preliminary risk damage assessment. In historical cities, the prediction of building response to settlements is necessary to reduce the risk of damage of the architectural heritage. The current method used to predict the building damage due to ground deformations is the Limiting Tensile Strain Method (LTSM). This method is based on an uncoupled soil-structure analysis, in which the building is modelled as an elastic beam subject to imposed greenfield settlements and the induced tensile strains are compared with a limit value for the material. This approach neglects many factors which play an important rule in the response of the structure to tunneling induced settlements. In this paper, the possibility to apply a settlement risk assessment derived from the seismic vulnerability approach is considered. The parameters that influence the structural response to settlements can be defined through numerical coupled analyses which take into account the nonlinear behaviour of masonry and the soil-structure interaction.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Settlements due to underground construction represent a risk for the architectural heritage, especially in The Netherlands, because of the combination of soft soil, fragile pile foundation and brittle, un-reinforced masonry façade. Modelling of soil-structure interaction is fundamental to assess the risk of building damage due to tunnelling. This paper presents results of finite element analyses carried out with different models for a simple masonry wall. Focus is paid on the comparison between coupled, uncoupled and semi-coupled analyses, in which the soil-structure interaction is represented in different ways. In particular, the implementation of a soil-structure interface model in the numerical analyses is analysed, in order to asses its validity. The aim of the research project is the development of a damage classification system for different building typologies.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

混农季节性放牧(agropastoral transhumance)通过作物种植和畜牧生产相结合的方式对不同海拔高度带上的资源进行相互补充利用,在亚洲兴都库什地区、青藏高原、横断山、东部及南部非洲、南美安第斯地区等具有悠久的历史。这种传统的生计系统几千年以来一直是居住在该地区的人类社会和自然生态系统相互作用的主要形式之一。这种传统的资源利用方式与山地自然植被以及特殊的山地人类文化和社会特征具有密切的协同演变关系。认识和理解这一关系,是山地生态学和人类学的核心科学问题之一。近年来,山地生态系统的多重功能性及动态演变对山区社会经济可持续发展的重要意义受到人们的不断关注。本文通过对云南省德钦县的12个自然村的混农季节性放牧以及对云南德钦、四川壤塘等山地植被格局特别是高海拔地带植被格局的的详细调查,探讨青藏高原东缘地区混农季节性放牧的主要特征、系统构成及相互关系,及其在全球变化、经济全球化和市场化及现代化过程中的变化趋势,分析混农季节性放牧与高山林线格局及生态系统的互动关系,旨在探讨山地地区人类活动与自然生态系统之间的互动关系,从而为山区社会经济可持续发展、环境建设和生物多样性保护等国家战略提供理论依据。 调查结果表明,混农季节性放牧是一种适应青藏高原东部高山峡谷地区环境因子及自然资源呈明显的垂直分布、资源数量稀少而时空分布异质性极高的生存环境的一种传统经济形式。这种传统的畜牧业的主要生产目的仍然是提供当地基本生存所需的产品,饲养牲口的种类和数量取决于农户的当地需求并且受资源的限制,因而维持在比较低的水平的。分布在不同海拔高度的放牧资源在一年中被牲口利用的时间也不同,互为补充,共同构成混农季节性放牧的资源基础。根据各社区永久居住点的位置和该村的土地资源特别是牧草地资源的分布范围,牲口迁移的距离和格局有较大的差异。。天然牧场仍然是最主要的畜牧业生产资源。混农季节性放牧中的农业系统和牧业系统互为补充,共同构成调查地区完整的的生计系统,农耕活动为放牧活动提供精饲料如粮食等和冬季饲料如秸秆, 其数量往往成为家庭畜牧业生产规模的主要决定因子之一。 通过对牲口数量和结构、牲口的时空迁移格局、牧业活动在整个经济活动中的相对重要性以及牧业活动和作物种植的关系方面的研究分析,混农季节性放牧在近几十年发生了深刻的变化。主要表现在牲口数量总体下降,牲口组成发生变化,牲口移动性降低、牧业活动的经济重要性下降以及牧业活动和种植活动之间的相互依存度降低等。上述变化的根本驱动力是发生在当地、地区及全球尺度上的环境、政治、社会经济、技术和文化等的变化,从而造成当地群众畜牧生产目标、土地利用和劳动力的分布等发生了变化。当地生计系统发生的改变可能会带来对方面而深刻的政治、社会经济、文化和生态影响。 混农季节性放牧这种古老的传统生计策略面临着许多挑战,如冬季饲料短缺、草场退化、缺乏市场竞争力、经济重要性降低、对年轻人缺乏吸引力、国家缺乏专门的政策指导等。与此同时,经济全球化、市场经济、新技术的应用、替代生计机会的增加、国家对于山地生态系统的作用的重新定位等也为传统生计系统转型、实现社会与生态共赢创造了机遇。 混农季节性放牧活动对亚高山及树线交错带生态系统系统的互动方式主要体现在以下几个方面:(1)牲口啃食、践踏等影响森林群落更新,改变森林群落的组成和结构,从而影响森林群落的演替进程和植被格局。林线边缘是搭建夏棚的首选地点,因此林线及树线交错地带就成了牲口活动的主要场所之一;(2)利用火烧开辟、维持和改良高山牧场; 3)在亚高山火灾迹地的放牧活动能够阻止火烧迹地的顺向演替; 4)牧民在林线附近获取建材和薪材等活动影响高山林线附近森林的结构和功能。 在调查区域,梅里雪山、白马雪山、甲午雪山的林线海拔高度在4200-4300m之间; 四川雅江、理塘一线,林线位置多在4300-4400m;四川壤塘二林场一带的林线主体在4100-4200m,在个别地区达到4300m; 在贡嘎山的南坡和东坡一带,林线位置在3600-3700m;而在四川松潘一带,林线位置主体在3700-3800米左右。树线高度的分布趋势和林线一致。混农季节性放牧及其有关人类利用活动使研究地区很多地方高山林线降低、树线交错带宽变窄或消失。在研究地区,总体情况是,阳坡和半阳坡(南坡、西南坡等)的林线和树线比阴坡和半阴坡(北坡、东北坡等)低,变化幅度达20-200m。这种差异主要是为了开辟牧场而人为清除了南向坡自然林线及其以上的植被从而使林线位置下降所致。在南坡自然林线保留得比较好的地方,林线和树线依然可以达到甚至超过北坡林线和树线的高度。放牧活动抑制了高山林线带火烧迹地的天然更新,从而使林线位置保持在目前的位置。 放牧活动对高山林线带森林群落更新的影响是显著的。自然林线内的乔木个体密度特别是新生苗和幼苗的密度大大高于非自然林线。没有放牧的自然林线及树线交错带内的I级个体(新生苗)密度达到725-2917株/公顷,而与之相对的处理样地内I级个体的密度只有0-228株/公顷;II级个体(高度10-50cm)也表现出类似的趋势,在没有放牧的自然林线及树线交错带样方内,其密度达到550-5208株/,而在放牧处理样方内只有14-321株/公顷。在非自然林线带样地内,在有正常放牧的样地内,完全缺乏I级个体。 从相对比例来看,没有放牧的样方内的I、II级个体在全部个体中所占的比例显著高于有放牧活动的样方。放牧使林线交错带的乔木幼苗数量显著减少,从而影响林线及树线交错带森林群落的天然更新过程。林线和树线交错带的灌木对乔木幼苗具有重要的保护作用,能够为树线树种如冷杉等幼苗的定居体提供有利的微气候环境,同时保护苗免受牲口的啃食和践踏。火烧以后接着进行放牧能够100%地抑制高山林线带的幼苗更新。 高山牧场放牧强度降低、使用时间缩短而低海拔地带放牧强度增加是研究地区混农季节性放牧系统的一个显著变化。这种变化也必然会引起各海拔带上的生态系统的变化。放牧强度的降低、生产性用火的停止将导致原来通过人工火烧而降低并通过进一步的火烧和放牧活动来维持的林线及其以上地带的灌木盖度和高度的增加,从而为林线森林群落的扩张创造条件。 青藏高原东部高山峡谷地区是我国重要的山地生态系统,在我国的生物多样性保护、生态环境建设、社会经济可持续发展战略中具有举足轻重的作用。正确认识人类特别是当地传统的生计系统与生态环境系统的互动关系是实现上述战略目标的前提。决策者必须以综合、系统的的视角协调促进社会经济可持续发展、保护生物及文化多样性和维持人、牲口和生态系统之间的平衡的多重目标。 Agropastoral transhumance, which makes a complementary exploitation of the natural resources at different altitudinal belts through a combination of migratory animal husbandry and crop cultivation, has a long history in Hindu-Kush Himalaya, Tibet Plateau, Hengduan Ranges, eastern and southern Africa and the Andes region of south America.For millennia, this traditional livelihood strategy has been one of the main forms of interaction between human societies inhabiting in these regions and their natural ecocystems. A close co-evolutionary relationship has been developed between this indigenous resources management systems and the mountain vegetation systems on the one hand and a unique set of cultural values and social features on the other. Understanding this relationship has been one of the core scientific issues in mountain ecology and anthropology. In recent years, the importance of the multiple functions of the mountain ecosystems and their dynamic changes in the sustainable socio-economic development of the mountain regions has gained increasing attention. This paper, which is based on a detailed study on the agropastoral practices of the 12 natural villages in Deqin County of Yunnan, and the mountainnn vegetation patterns in Deqin of Yunnan and Rangtang County of Sichuan, intends to reveal the major characteristics, system composition and the inter-relations of the subsystems of the agropastoral transhumance in Eastern Tibetan Plateau as well as the trends of changes of the system within the context of global changes, economic globalization and modernity process of China and analyze the relations between agropastoral transhumance and alpine ecosystem, ao as to understand the interactions between human activities and natural ecosystems of the mountains and provide theoretical basis for the national strategies in eocioeconomic development, environmental reconstruction and biodiversity conservation in the mountain regions. Results of the survey indicate that agropastoral transhumance in the investigated area is a traditional economic form that is highly adapted to the eastern Tibet Plateau where the topography features high peaks and deep gorges and where the highly variable environmental parameters and scanty natural resources exhibit a distinct vertical spectrum of distribution and great temporal and spatial heterogeneity. The main objective of pastoral management is still aimed at the production of basic goods and services of local people and thus the type and size of animals raised for each household mainly depend on local needs and are limited by the availability of natural resources. The scale of production is relatively low. Pastoral resources at different altidudinal belts are complementarily used at different seasons of a year and thus form the resources basis for agropastoral production of the study area. Migration distances and patterns vary with the location of the permanent settlements, the elevational distribution range of the resources of the villages concerned. Natural pastures (rangelands) are the main fodder resources and sumplement feedings only account for less than 5% of the total fodder consumption. Crop cultivation and pastoral activities support each other to form a complete livelihood system. The ability of the farmig lands (crop cultivation) to provide the pastoral activities with concentrates and sumplements often becomes a main factor limiting the scale of livestock production at household level. Agropastoral transhumance is experiencing drastic changes in recent decades as is reflected in the size and composition of animals, the seasonal migration pattern, the relative importance of pastoralism in the household economy and the interplays of agricultural and pastoral elements of the system. In general, there is a decline in animal population and mobility, a shift in animal composition to meet new needs arising from changed macro-economic situation, a decrease in the relative importance in the household economy and an increasing decoupling of agro&pastoral relations. The fundamental divers of these changes can be traced to environmental, social, economic, technological and cultural changes from local to global levels and such changes have further caused local changes in livestock management objectives, land use and distribution of labor forces. Changes in local livelihood systems could have profound political, socioeconomic, cultural and ecological conseuquences. Agropastoral transhumance, as an age-old traditional livelihood strategy, is facing multifacet challenges, such as winter fodder shortage, rangeland degradation, lack of market competitiveness, decrease in economic importance, lack of appreciation among the young generation and adequate policies from the government. At the same time, economic globalization, market economy, intrdoctution of new technologies, increase of alternative income generating opportunities and the national re-oreitation of policies on mountain ecosystems have all brought about new opportunities for the transformation of the traditional livelihood system and the synchronized development of local society and the environment. Agropastoral transhumance interacts with the ecosystems at the timberline and treeline ecotone mainly through the following aspects: 1)Animal browsing and stamping affect the regeneration process of the forest communities and alters the composition and structure of the forest which in turn affect the succession process and vegetation pattern of the forest communities. Forest edges are the priority locations for summer houses and therefore the timeline and treeline area becomes the major venues of aninal activities; (2)herders create, maintain and improve pastures through burning that remove the forest communities at the timeline and treeline ecotone; 3)immediate grazing on the fire sites can significantly prevent the fire sites from perogressive succession; and 4)herders harvesting of construction timber and firewoods affects the structure and functions of the forest communities at the timberline and treeline zone. Timberline position in the survey region shows geographical variations. It is around 4200-4300m in Meilixueshan, Baimaxueshan and Jiawuxueshan in Northwest of Yunnan and rises to 4300-4400m in Yajiang County and Litang County of Sichuan. In Rangtang of Sichuan, it is between 4100-4200m, though reaching 4300m in localized sites. In the southern and eastern slopes of Gongga Mountain, the timberline is only between 3600m and 3700m and in Songpan County at the upper reach of the Minjiang River the timberline is around 3700-3800m.Treeline pattern follows similar trend. In many places, agropastoral transhumance and related human activities have lowered the timberline and treeline and narrowed or removed the treeline ecotone. In the area of survey, generally speaking, timberlines and treelines are lower on the southern slopes than on the northern slopes, with a difference between 20 and 200m. This is mainly because that the use of fires to crerate pastures has removed the forest vegetation at the previous timberline and above. In fact, in many places, well-preserved forests on the south slopes have even high timberline position that the corresponding northern slopes. At subalpine zone, grazing activities could have prohibited the natural regeneration of many forest fire sites and maintained the forest position at the present level. Grazing has a significant impact on the regernation process of forest communities at the timberline zone. Natural timberline and treeline ecotone has much higher density of treeline species individuals especially the emergents and seedlings than the timberlines that are maintained by human activities. In natural timberline and treelien ecotone without grazing interference, the density of the I Class seedlings (less than 10cm in height) ranges 725-2917 /hm2; while that in the treatment plots (with grazing disturbance) is only 0-228//hm2;II Class seedlings (10-50cm)exhibit similar density trends, reaching 550-5208//hm2 in natural timberline without grazing but only 14-321//hm2 in the plots with grazing treatment. In the man-created timberlines, there is no I Class seedling at all in plots with normal grazing activities. In relative terms, in plots without grazing activities, the propotion of I Class and II Class seedlings is much higher than that in plots with grazing. Grazing activities have significantly reduced the number of seedlings in the timberline ane treeline ecotone, and thus affect the natural regeneration process of the forests. Shrubs at the timberline and treeline ecotone can effectively protect the seedlings from severe climate and animal tramping, thus increasing the survival rate of the seedlings. Grazing following fires can completely inhibit forest regeneration process at timberline. Changes in agropastoral transhumance will have great impact on the timberline and treeline pattern of the studied area. The decrease in grazing intensity on alpine pastrues and the cessation of the use of fires will result an increase in the cover and height of shrubs above the present human-maintained treeline, which will create further condition for the expansion of timberline forest communities. Eastern Tibet Plateau harbors some most important mountain ecosystems of China that are of vital importance to the country’s strategy in biodiversity conservation, environmental construction and sustainable sociaoeconomic development. A proper knowledge of the interactions between traditional livelihood systems and the ecosystems in the region is a precondition to the realization of the above strategic goals. Therefore, the decision-makers must have a holistic and systemic perspective so as to integrate the multiple objectives of promoting sustainable socioeconomic development, conserving biological and cultural diversity and maintaining the balances among people, animal population and the ecosystems.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The interactions among industrial development, land use/cover change (LUCC), and environmental effects in Changshu in the eastern coastal China were analyzed using high-resolution Landsat TM data in 1990, 1995, 2000, and 2006, socio-economic data and water environmental quality monitoring data from research institutes and governmental departments. Three phases of industrial development in Changshu were examined (i.e., the three periods of 1990 to 1995, 1995 to 2000, and 2000 to 2006). Besides industrial development and rapid urbanization, land use/cover in Changshu had changed drastically from 1990 to 2006. This change was characterized by major replacements of farmland by urban and rural settlements, artificial ponds, forested and constructed land. Industrialization, urbanization, agricultural structure adjustment, and rural housing construction were the major socio-economic driving forces of LUCC in Changshu. In addition, the annual value of ecosystem services in Changshu decreased slightly during 1990-2000, but increased significantly during 2000-2006. Nevertheless, the local environmental quality in Changshu, especially in rural areas, has not yet been improved significantly. Thus, this paper suggests an increased attention to fully realize the role of land supply in adjustment of environment-friendly industrial structure and urban-rural spatial restructuring, and translating the land management and environmental protection policies into an optimized industrial distribution and land-use pattern.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Rapid urbanization and industrialization in southern Jiangsu Province have consumed a huge amount of arable land. Through comparative analysis of land cover maps derived from TM images in 1990, 2000 and 2006, we identified the trend of arable land loss. It is found that most arable land is lost to urbanization and rural settlements development. Urban settlements, rural settlements, and industrial park-mine-transport land increased, respectively, by 87 997 ha (174.65%), 81 041 ha (104.52%), and 12 692 ha (397.99%) from 1990 to 2006. Most of the source (e.g., change from) land covers are rice paddy fields and dryland. These two covers contributed to newly urbanized areas by 37.12% and 73.52% during 1990-2000, and 46.39% and 38.86% during 2000-2006. However, the loss of arable land is weakly correlated with ecological service value, per capita net income of farmers, but positively with grain yield for some counties. Most areas in the study site have a low arable land depletion rate and a high potential for sustainable development. More attention should be directed at those counties that have a high depletion rate but a low potential for sustainable development. Rural settlements should be controlled and rationalized through legislative measures to achieve harmonious development between urban and rural areas, and sustainable development for rural areas with a minimal impact on the ecoenvironment. (C) 2009 Elsevier Ltd. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The fluvio-lacustrine sequence in the Nihewan Basin is an important archive of late Pliocene-Pleistocene climate and environment changes in temperate northern China, which provides excellent sources of early human settlements in high latitude East Asia. The recent years have witnessed a considerable progress in the paleomagnetic dating of its stratigraphy, which has notably increased our understanding of a series of important issues such as the early human occupation in the Old World, the infilling history of the Nihewan Basin, and the chronological sequence of the Nihewan faunas. Up to now, the long-term paleoenvironmental changes directly retrieved from this basin, which might influence the evolution and expansion of early humans in the Nihewan Basin, are still poorly constrained, although several paleoclimatic records have been retrieved from this area. In this study, a combined mineral-magnetic and geochemical investigation was carried out on the fluvio-lacustrine sequence from the Dachangliang section at the eastern margin of the basin in order to reveal its rock magnetic and environmental magnetic characteristics and its implications for early human evolution in East Asia. The major findings and conclusions are listed as the following: First, there is an increased cooling coupled with an intensified aridification recorded in the fluvio-lacustrine sequence of the Dachangliang section. The cooling is related to an up-section decrease in propensity to chemical weathering as inferred from an increase in low-field susceptibility after cycling to 700 °C. Close to 700 °C, reacting chlorite is providing the iron source for newly formed very fine-grained ferrimagnetic minerals which enhances the susceptibility signal. The reactivity of chlorite after annealing at temperatures above 600 °C is documented with X-ray diffraction. Second, degrees of chemical weathering in the Nihewan Basin are further estimated by clay mineralogy (i.e. chlorite and illite contents and chlorite/illite ratio) and a series of major element proxies (i.e. Na2O/Al2O3 versus K2O/Al2O3 diagram, Al2O3-(CaO + Na2O)-K2O ternary diagram (A-CN-K), chemical index of alteration (CIA), (CaO + Na2O + MgO)/TiO2, (CaO + Na2O + MgO + K2O)/(TiO2 + Al2O3), CaO/Al2O3 and CaO/TiO2). The up-section decrease in propensity to chemical weathering suggested by the aforementioned rock mangetic measurement is further confirmed by these geochemical analyses. Combining the chemical weathering records from the Nihewan Basin, Chinese Loess Plateau, South China Sea and eastern China, we find that the consecutive decreasing trend in chemical weathering intensity during the late Cenozoic is ubiquitous across China. This pattern may result from a long-term decreasing East Asian summer monsoon and increasing East Asian winter monsoon, and thus a consecutive increasing of aridification and cooling in Asia during the Quaternary. Furthermore, the chemical weathering intensity increased from South China to North China during the Quaternary, in line with the decreasing East Asian summer monsoon and increasing East Asian winter monsoon and thus the gradually intensified aridification and cooling from South China to North China. Third, a combined mineral-magnetic and geochemical investigation provides evidences that the large-amplitude alterations of concentration of magnetic minerals mainly result from preservation/dissolution cycles of detrital magnetic minerals in alternately oxic and anoxic depositional environments. The preservation/dissolution model implies that the high-magnetic and low-magnetic cycles of this sedimentary sequence represent glacial and interglacial climate cycles, respectively. This contribute significnatly to our understanding of the link between climate and magnetic properties. Finally, the paleoclimatic implications of these rock magnetic and geochemical characteristics significantly increase our understanding of the general setting of early humans in high northern latitude in East Asia. We propose that the cold and dry climate may have contributed significantly to the expansion and adaptation of early humans, rather than bringing hardship, as is often thought. The relationship between magnetic properties and climate possibly provides valuable information on the climatic context of the Paleolithic sites in the basin, especially whether the occupation occurred during an interglacial or glacial period.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The aim of the studies in the Perznica River catchment were relief changes caused by the development of transportation infrastructure. This type of transformation is dependable on the state of economy and the settlements. The development of transportation network in the last two hundred years was examined through the analysis of archival cartographic materials – maps from the years 1789, 1855, 1877, 1935 – and the comparison with the situation from mid 1980s. The Perznica River catchment has an area of 249 km2 and it is located in north-western Poland in the central part of the Drawskie Lakeland macroregion, which belongs to the West Pomeranian Lakeland. The heterogeneous Perznica River catchment relief has a denivelation of 159 m and is within 60 and 219 m a.s.l. The study area is within the Parsęta River lobe. A number of subzones, whose morphological diversity and diversity of sediments lithofacies is mainly a reflection of areal deglaciation of the continental ice-sheet marginal zone, has been distinguished and these are: • subzone of the internal kame moraine – the undulated moraine upland, diversified by kame forms and kettle holes, • subzone of ice-free space forms – the uplands of kame plateaux, • subzone of melt-out lake basins – Lake Wielatowo basin with a characteristic collar ridge, • morphological levels of the northern Pomeranian sloping surface – mainly flat moraine uplands and small outwashes. The economic development of the Perznica River catchment advanced in close connection with the physical and geographical context, mainly with the relief, soils and hydrological conditions. As a result, the flat moraine uplands and marginal outflow plains, which were easiest to cultivate, have been developed and populated faster than any other. Since the early medieval period, large, compact villages, often centered around big estates, were emerging in those areas. In areas with a high relief energy–kame-melt moraines, ice-free space forms and ridges around melt-out lake basins–farming entered on a larger scale from the eighteenth century. Scattered settlements in those areas forced the creation of a dense access road network to farms and fields. In the case of anthropogenic forms of transportation with denivelation exceeding 1 m in the study area, road excavations are present for 37.3 km, road undercuttings for 43.8 km and road embankments for 38.7 km in total length. That gives a high ratio of density of such forms, equal to 2.1 km per km–2.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In 1750 the lower Medway Valley, the area between the towns of Maidstone and Rochester, was firmly part of Kent's 'Garden of England'. A century later, this tranquil, agrarian landscape had been transformed into a hive of industry and commerce, through the emergence of papermaking, cement manufacture, brickmaking, brewing, ship and barge building, seed crushing and engineering. The lower Medway Valley became synonymous with the production of Portland cement, stock bricks and the steam engines of Aveling and Porter, yet, by the end of the Second World War, much of this industry was gone. "The Medway Valley: A Kent Landscape Transformed", the first Victoria County History publication in Kent for over 75 years, charts this cyclical story of landscape change. It explores how the quiet, rural landscape of a collection of eight riverside parishes around Rochester was dramatically transformed during industrialization, before returning to its formal rural state. This volume traces the impact of industrial development and decline on the valley and its people. It details changing patterns of work and society, the creation of new settlements and the pivotal role of the river in all aspects of village life reflecting two centuries of change and upheaval.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Urban spectacles such as the Olympic Games have been long perceived as being able to impose desired effects in the city that act as host. This kind of urban boost may include the creation of new jobs and revenue for local community, growth in tourism and convention business, improvements to city infrastructure and environment, and the stimulation of broad reform in the social, political and institutional realm. Nevertheless at the other end of the debate, the potentially detrimental impacts of Olympic urban development, particularly on disadvantaged and vulnerable groups, have also been increasingly noticed in recent years and subsequently cited by a number of high profile anti-Olympic groups to campaign against Olympic bids and awards. The common areas of concern over Olympic-related projects include the cost and debts risk, environmental threat, the occurrence of social imbalance, and disruption and disturbance of existing community life. Among these issues, displacement of low income households and squatter communities resulting from Olympic-inspired urban renewal are comparatively under-explored and have emerged as an imperative area for research inquiry. This is particularly the case where many other problems have become less prominent. Changing a city’s demographic landscape, particularly displacing lower income people from the area proposed for a profitable development is a highly contentious matter in its own right. Some see it as a natural and inevitable outgrowth of the process of urban evolution, without which cities cannot move towards a more attractive location for consumption-based business. Others believe it reflects urban crises and conflicts, highlighting the market failures, polarization and injustice. Regardless of perception,these phenomena are visible everywhere in post-industrial cities and particularly cannot be ignored when planning for the Olympic Games and other mega-events. The aim of this paper is to start the process of placing the displacement issue in the context of Olympic preparation and to seek a better understanding of their interrelations. In order to develop a better understanding of this issue in terms of cause, process, influential factors and its implication on planning policy, this paper studies the topic from both theoretic and empirical angles. It portrays various situations where the Olympics may trigger or facilitate displacement in host cities during the preparation of the Games, identifies several major variables that may affect the process and the overall outcome, and explores what could be learnt in generic terms for planning Olympic oriented infrastructure so that ill-effects to the local community can be effectively controlled. The paper concludes that the selection of development sites, the integration of Olympic facilities with the city’s fabric, the diversity of housing type produced for local residents and the dynamics of the new socioeconomic structure.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Este estudio intenta esclarecer las transformaciones físicas y socioeconómicas de los asentamientos rurales de la región española de Castilla y León, durante la segunda mitad del siglo XX. Se analiza la evolución temporal de la forma urbana a través de un Sistema de Información Geográfico (SIG), calculando unos índices métricos y comparándolos con la información demográfica histórica. Los resultados pretenden mostrar los efectos de la especialización funcional económica, causada por la integración en las jerarquías productivas globales, sobre la estructura urbana. La pérdida gradual de las características tradicionales de los pueblos castellanos, como la compacidad y la integración en el entorno, debido a la pérdida o degradación de la arquitectura popular y la construcción de nuevas edificaciones industriales, supone un riesgo para las futuras políticas de desarrollo local. Se considera necesario preservar la identidad paisajística y evitar la destrucción del patrimonio cultural para poder revitalizar estos territorios.

Relevância:

10.00% 10.00%

Publicador: