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1.
A large number of pitchstone fragments and artefacts have recently been discovered at a Neolithic settlement site in Ballygalley, Co. Antrim, Northern Ireland. They consist predominantly of flakes and un‐reworked lumps and cores, with only one complete tool being found. Since no sources of workable pitchstone exist in Ireland, the source must have been the abundant pitchstone volcanic rocks found on the Hebridean Islands of northwest Scotland. The composition of the glass from a number of artefacts is highly siliceous, indicating that they were derived from pitchstones on the Island of Arran; pitchstones from all other Scottish locations are less silica‐rich. In addition, analysis of pyroxene and amphibole microcrystallites within the pitchstone suggests that the Corriegills area of Arran is the most likely source of the Ballygalley artefacts, although the precise outcrop has proved elusive. These finds, and others across Ireland, show that raw materials were being transported and probably traded over considerable distances despite there being suitable alternative sources of material for making tools (flint, etc.) available in the local area. This suggests that the pitchstone had a very specialist use. © 2002 Wiley Periodicals, Inc.  相似文献   

2.
“两湖一库”是典型的喀斯特高原湖泊,湖库周边生态环境极为脆弱,其土地利用变化对所在区域生态安全/供水安全及社会经济发展带来重要影响。基于“源-汇”理念和黔中“两湖一库”地区1998-2018年4期遥感解译数据,采用土地利用动态度模型分析近20年来“两湖一库”地区土地利用动态演变规律,并运用定量与定性分析相结合的方法探究其驱动力。结果表明:(1)1998-2018年建设用地、林地、未利用土地(主要为暂时性未利用土地)面积不断增加,水域面积波动减少,耕地、草地面积持续减少,其中建设用地和未利用土地在各时段均为变化最活跃的地类。(2)年均综合土地利用动态度由1998-2008年的1.33%提高至2008-2013年的2.4%和2013-2018年的2.3%。近10年各地类间的相互转换较10年前更为活跃。(3)主要的土地利用“源-汇”转换关系表现为耕地转为林地和建设用地、草地转为林地和耕地。(4)各地类加速向建设用地转换,建成区面积迅速扩张,“两湖一库”供水压力进一步增大。(5)人口压力、经济发展等因素是“两湖一库”地区建设用地扩张的主要驱动因素,政策因素对林地和水域面积变化有重要影响。研究结果可以为“两湖一库”地区土地利用、规划及社会-经济-生态协调发展提供参考。   相似文献   

3.
李雪  杨海娟 《地下水》2012,(2):196-198
通过定性与定量相结合,对比研究等分析方法研究宜君县近9年来耕地变化的主要因素及耕地变化驱动力。结果表明总人口、国民生产总值、二三产业增加值、固定资产投资是耕地变化的主要驱动力,利用回归分析方法预测宜君县今后一段时间内,在影响耕地的驱动力因子保持不变的情况下,耕地面积将持续减少,因此,为了宜君县的可持续发展,认为应该做好强化土地用途管制制度,建立耕地保护目标责任制,重视提高耕地质量的技术等措施。  相似文献   

4.
魏冲  董晓华  刘冀  李英海  万浩  喻丹  徐时进  王凯 《水文》2019,39(6):20-26
常用的水土保持措施是退耕还林,但淮河流域是中国重要的农业产区,大规模实行退耕还林并不现实,所以通过调整耕地类型来减少水土流失可能是解决社会经济发展和生态保护矛盾的好方法。为研究不同耕地类型对流域水文要素及产沙的影响,考虑水田和旱地两种耕地类型对淮河息县水文站上游流域构建SWAT模型,构造A(实际耕地利用方式)、B(所有耕地为水田)和C(所有耕地为旱地)三种耕地类型情景,比较不同耕地类型情景下流域水文要素及产沙的变化情况。研究结果表明:所构建的SWAT模型在息县流域径流及泥沙模拟中具有良好的适用性,R2和NSE(Nash Sutcliffe Efficiency)均达到0.75以上;水田和旱地两种不同耕地类型对流域多年年均蒸散发及多年平均径流量影响较小,但对流域产沙量影响较大,在汛期更为明显,模拟期内每平方公里水田每年最多比旱地少产沙491.8t,平均每年少产沙约208.7t。采取水田耕种比旱地耕种更有利于减少息县流域内的水土流失。  相似文献   

5.
The crucial and difficult task in landslide susceptibility analysis is estimating the probability of occurrence of future landslides in a study area under a specific set of geomorphic and topographic conditions. This task is addressed with a data-driven probabilistic model using likelihood ratio or frequency ratio and is applied to assess the occurrence of landslides in the Tevankarai Ar sub-watershed, Kodaikkanal, South India. The landslides in the study area are triggered by heavy rainfall. Landslide-related factors—relief, slope, aspect, plan curvature, profile curvature, land use, soil, and topographic wetness index proximity to roads and proximity to lineaments—are considered for the study. A geospatial database of the related landslide factors is constructed using Arcmap in GIS environment. Landslide inventory of the area is produced by detailed field investigation and analysis of the topographical maps. The results are validated using temporal data of known landslide locations. The area under the curve shows that the accuracy of the model is 85.83%. In the reclassified final landslide susceptibility map, 14.48% of the area is critical in nature, falling under the very high hazard zone, and 67.86% of the total validation dataset landslides fall in this zone. This landslide susceptibility map is a vital tool for town planning, land use, and land cover planning and to reduce risks caused by landslides.  相似文献   

6.
This work evaluates the changes of nitrate-nitrogen (NO3-N), ammonium-nitrogen (NH4-N), total phosphorus (P) and chemical oxygen demand (COD) concentrations in stream waters as related to the land use/land cover (LULC) alterations within eight small (5–39 km2) tile-drained catchments in the southern part of The Czech Republic in the period 1993–2010, when massive grassing of arable land took place. The robust tools of seasonal Mann–Kendall trend test and LOcally WEighted Scatterplot Smoothing methods were employed to reveal trends of the monitored parameters with adjustment to hydrology. Using principal component analysis and multiple regressions, statistically significant factors with highest impacts on the assessed water quality parameters were identified. Besides indicators of LULC changes in the catchments and their various zones, information of built tile drainage systems were used along with factors reflecting point pollution sources such as the population number, sewerage type and proximity to a watercourse, effectiveness of wastewater treatment, and number of livestock units. The change in LULC was essential only for NO3-N concentrations, when grassing of arable land, presence of water ponds, areas of permanent cultures and also areas of drained land explained up to 90.6 % NO3-N variability and nitrate-nitrogen concentrations showed a significantly decreasing trend in all monitored catchments during the evaluated period. LULC changes within infiltration vulnerable zones were discovered as less important for the assessed water quality parameters compared to LULC changes in the whole catchment area. However, for NH4-N, P and COD, the results did not enable a definite quantification of the effects of LULC changes. The influence of non-point pollution sources on these parameters was revealed as uncertain and was heavily overshadowed by point sources, in particular by wastewater management, and livestock numbers, although the proportion of arable land in tile drainage subcatchments was discovered fundamental in case of the COD. The increasing numbers of livestock, population, and changes in sewage treatment led in some catchments to significant worsening of water quality. Achieved findings may be critical for supporting water quality policy and management decisions.  相似文献   

7.
该文分析了山东省耕地总面积、人均耕地面积变化的历史特征及耕地数量变化的空间差异。在对人口峰值状态下的耕地需求与耕地数量变化趋势进行分析的基础上,预测2020年全省耕地资源的安全需求量为735万hm^2。因此必须加强对耕地的保护,并提出了保障粮食安全的对策。  相似文献   

8.
根据山东省2002-2008年耕地面积和社会经济发展统计数据,分析了全省耕地、人口变化趋势,利用主成分分析法通过SPSS定量分析了影响耕地变化的驱动因子,依据主成分分析的结果,重点进行了人口、经济和城市建设等因素的驱动分析。  相似文献   

9.
山东省文登市耕地面积6.2137万hm2,人均耕地不足0.097 hm2,耕地后备资源稀缺,土地供需矛盾日益突出。随着经济社会快速发展,全市建设项目占用耕地数量逐年增加。近年来,文登市在被占用耕地耕作层土壤剥离方面作了一些探索,取得了较好成效,走出了一条活用表层熟土再造肥田沃土的新路子。  相似文献   

10.
李涛  王步远  刘建伟 《山东地质》2011,(12):43-45,52
临沂市属于传统农业大市,耕地资源丰富,农用地占土地总面积的比例较大。近年来,该市始终把保护耕地放在经济发展的第一位,努力做到节约集约用地,用尽可能少的土地产出尽可能多的效益。但也存在一些值得重视的问题,需深入思考与不断探索。该文对临沂市土地资源利用现状进行分析,查找耕地减少的原因及保护过程中存在的问题,并提出解决办法。  相似文献   

11.
In Precision Agriculture one of the basic tasks is the classification of land zones in either arable or non-arable land. Several studies have been conducted using data obtained from soil analysis or local exploration of the parcels. However, sometimes only data from satellite images are available and then the problem not only becomes more challenging but also more interesting to solve because it is much more cost-effective. In this paper, we consider different spectral and thermal bands from the Landsat 8 satellite images corresponding to a vineyard located in Galicia, a region in Northeastern Spain, and apply a range of supervised Machine Learning methods to classify the different land zones. We conclude that an adequate choice of the algorithm parameters together with feature selection techniques can yield a classification that is both highly effective and efficient.  相似文献   

12.
This study investigates the relationship between environmental change and the origins of agriculture in the Near East, with special reference to the Konya and Beysehir-Sušla Basins of south central Anatolia. The Konya Basin, now largely dry, was formerly occupied by an extensive lake, which last attained a high level between 23,000 and 17,000 years ago. It is concluded that there was only an indirect link between the drying up of the former Konya Lake and the appearance of early agricultural (Neolithic) settlements on the floor of the plain. An equally important factor was the creation of new land and water resources which resulted from changes in river regimes and alluvial sedimentation after the end of the Pleistocene. Neolithic sites were not only clustered on water-retentive alluvial soils, but have also been partly buried by Holocene alluviation. The revised site chronology which follows from these geoarchaeological observations has significant implications for the interpretation of the Neolithic settlement system in south central Turkey.  相似文献   

13.
中国人均耕地资源不足,中低山区耕地资源安全问题更为突出。高速城镇化进程致使耕地数量减少,耕地资源安全受到严重威胁。耕地数量安全作为耕地资源安全的重要构成,具有可量化与可调控等特点,更具研究价值和实际操作性。以中低山区为研究区,对区域耕地资源数量进行调查研究,通过实证方法对耕地结构、变化、影响因素、利用中存在的问题进行分析,提出利用中低山区丰富的耕地后备资源合理补充耕地、有序推进"山地整理"满足城镇化需求、实施中低山区城乡建设用地增减挂钩、挖掘农村建设用地潜力等方法,以保障中低山区耕地资源数量安全。  相似文献   

14.
The results of detailed pollen‐analytical investigations of a core from Lough Dargan, Co. Sligo, Ireland are presented. The pollen diagram spans much of the postglacial and documents changes in woodland composition and cover, and farming activity. Special attention is paid to prehistoric farming and to the significance of cereal‐type pollen. The first sign of arable farming coincides with the Elm Decline at c. 3760 BC. This early Neolithic farming phase extended over c. 750 years, the main Landnam phase having a duration of 700 years. After a break of about three centuries, Neolithic farming resumed. Late Neolithic farming was at first predominantly pastoral, but later (c. 2360–2130 BC) it had a distinct arable component. In the early Bronze Age, beginning c. 2130 BC, farming increased and woodland was substantially reduced for the first time. From then until the beginning of the late Iron Age (c. 80 BC), there was a sustained and strong human impact. In the late Iron Age, a distinct lull in pastoral farming lasted for about four centuries (c. 80 BC–AD 350). This facilitated woodland regeneration that included yew. Substantial woodland clearance, and farming that included a considerable arable component, characterized the Medieval and later periods. The changes recorded at L. Dargan and other sites in the region are discussed in the light of evidence for climate change provided by regional and super‐regional climate proxies. It is argued that climate may not have been a decisive factor in determining human impact and farming activity.  相似文献   

15.
The arable soils from two multiperiod settlements were analyzed to identify changes in agricultural methods over time. The settlement middens were also analyzed to determine whether potential fertilizers were discarded unused. Results suggest that in the Neolithic period (˜4000–2000 B.C. in the UK) the arable soils at Tofts Ness, Orkney, and Old Scatness, Shetland, were created by flattening and cultivating the settlements' midden heaps in situ. The arable area at Tofts Ness was expanded in the Bronze Age (˜2000–700 B.C. in the UK), and the new land was improved by the addition of ash, nightsoil, and domestic waste. Cultivation continued briefly after the fields were buried in windblown sand in the Late Bronze Age or Early Iron Age, but by the Early Iron Age cultivation ceased and organic‐rich material was allowed to accumulate within the settlement. By contrast, at Old Scatness, arable production was increased in the Iron Age (˜700 B.C.–A.D. 550 in Scotland) by the intensive use of animal manures. The results indicate that during the lifespan of the two settlements the arable soils were fertilized to increase production, which was intensified over time. © 2006 Wiley Periodicals, Inc.  相似文献   

16.
长江三角洲地区土地利用变化及对策研究   总被引:1,自引:0,他引:1  
长江三角洲地区土地利用历史悠久,是我国传统的人口密集区和土地高度集约化利用区。早在7~6kaB.P.就产生了马家浜文化,明清时期已成为中国人口最密集的地区。随着经济的发展,土地集约化经营水平不断提高,土地利用类型越来越复杂。然而,由于人口增长,人均耕地面积越来越少,由200年前的0.09hm2人均耕地面积减至2000年仅为0.048hm2,而且长江三角洲地区土地利用中多种问题并存:一方面是耕地数量不断减少,质量下降;另一方面是建设用地利用效率低下,大量土地闲置。因此,有必要进行综合治理,加以控制和调整。文章建议可采用的土地利用对策有:加大科技投入,转变增长方式;集约利用城镇及农村居民点用地;加快农业产业化步伐,调整农业结构;控制环境污染,改善土地质量;注意土地利用规划的实施,实现土地资源优化配置。  相似文献   

17.
长江三角洲地区土地利用变化及对策研究   总被引:11,自引:0,他引:11       下载免费PDF全文
长江三角洲地区土地利用历史悠久,是我国传统的人口密集区和土地高度集约化利用区。早在7~6kaB.P.就产生了马家浜文化,明清时期已成为中国人口最密集的地区。随着经济的发展,土地集约化经营水平不断提高,土地利用类型越来越复杂。然而,由于人口增长,人均耕地面积越来越少,由200年前的0.09hm2人均耕地面积减至2000年仅为0.048hm2,而且长江三角洲地区土地利用中多种问题并存:一方面是耕地数量不断减少,质量下降;另一方面是建设用地利用效率低下,大量土地闲置。因此,有必要进行综合治理,加以控制和调整。文章建议可采用的土地利用对策有:加大科技投入,转变增长方式;集约利用城镇及农村居民点用地;加快农业产业化步伐,调整农业结构;控制环境污染,改善土地质量;注意土地利用规划的实施,实现土地资源优化配置。  相似文献   

18.
广东省耕地面积变化的宏观驱动机制研究   总被引:31,自引:0,他引:31  
黄宁生 《地球科学》1999,24(4):359-362
主要研究了广东省改革开发近20年来耕地面积的减少过程,讨论了经济、人口等因素对耕地变化的影响机理,得出以下主要结论:(1)经济增长是影响广东省耕地面积变化的主要宏观驱动因子,耕地快速减少在发生时间上与经济的“过热”增长基本同步;在空间分布上具有半环带状结构的特点,与地区间经济发展速度和水平的差异相一致.(2)改革开放以来,广东省经济的高速增长是以大量的自然资源消耗为代价的(以耕地资源为代表),经济  相似文献   

19.
Landslides the most common geo-hazard in hilly terrain are short lived phenomena but cause extraordinary landscape changes and destruction of life and property. The frequency and intensity of landslides occurrences along NH-21 during the rainy season not only disrupts traffic movement but also misbalance the agro-economic and developmental activities of the region frittering away thousand crores of rupees from the exchequer. An assessment of landslide susceptibility is, therefore, a prerequisite for sustainable development of the region. The present study deals with the preparation of macro-zonation maps of landslide susceptibility in an area of about 100 sq km on 1:50,000 scale across Garamaura-Swarghat section of National Highway-21. The map has been prepared by superimposing the terrain evaluation maps in a particular zone such as lithological map, structural map, slope morphometry map, relative relief map, land use and land cover map and hydrological condition map using landslide susceptibility evaluation factor rating scheme and calculating the total estimated susceptibility as per the guidelines of IS: 14496 (Part-2) 1998). Numerical weightages are assigned to the prime causative factors of slope instability such as lithology, structure, slope morphometery, relative relief, land use and groundwater conditions as per the scheme approved by Bureau of Indian Standard for the purpose of landslide susceptibility zonation. The area depicts zones of different instability. The identified susceptibility zones compared with landslide intensity in the area show some congruence with the weightages of the inputs. The incongruence in intensity and frequency of landslide occurrences and the inferred susceptibility zones of BIS scheme allow other geotechnical considerations and causative factors to be incorporated for the landslide susceptibility zonation.  相似文献   

20.
Based on the inventory, revision, and analysis of stratigraphic, paleontological, and lithofacies data on the area of Ordovician deposits in the southern Siberian Platform (Irkut amphitheater), the refined and detailed schemes of biofacies zonation of this paleobasin are substantiated. Schemes of zonation have been compiled for the Nyaian, Ugorian, Kimaian, Mukteian, Volginian, Kirenskian-Kudrinian, Chertovskian, and Baksanian Horizons of the regional Ordovician stratigraphic chart of the Siberian Platform. The schemes present biofacies different in lithologic composition, spread of dominant groups of fauna, and hydrochemical regime (normal-marine salinity, freshwater, or high salinity). It is shown that contrasting changes in paleogeographic environments and the spread of faunal communities under changing environmental conditions were influenced by the transgression-regression cyclicity of the evolution of the Siberian Platform paleobasin and by the proximity of the land. Specific groups of fauna localized in particular facies are described. These groups are regarded as communities that were the first to occupy the littoral zones of epicontinental sea basins in the Ordovician.  相似文献   

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