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1.
Devleena Mani T. Satish Kumar M. A. Rasheed D. J. Patil A. M. Dayal T. Gnaneshwar Rao V. Balaram 《Natural Resources Research》2011,20(1):75-88
The association of iodine with organic matter in sedimentary basins is well documented. High iodine concentration in soils
overlying oil and gas fields and areas with hydrocarbon microseepage has been observed and used as a geochemical exploratory
tool for hydrocarbons in a few studies. In this study, we measure iodine concentration in soil samples collected from parts
of Deccan Syneclise in the west central India to investigate its potential application as a geochemical indicator for hydrocarbons.
The Deccan Syneclise consists of rifted depositional sites with Gondwana–Mesozoic sediments up to 3.5 km concealed under the
Deccan Traps and is considered prospective for hydrocarbons. The concentration of iodine in soil samples is determined using
ICP-MS and the values range between 1.1 and 19.3 ppm. High iodine values are characteristic of the northern part of the sampled
region. The total organic carbon (TOC) content of the soil samples range between 0.1 and 1.3%. The TOC correlates poorly with
the soil iodine (r
2 < 1), indicating a lack of association of iodine with the surficial organic matter and the possibility of interaction between
the seeping hydrocarbons and soil iodine. Further, the distribution pattern of iodine compares well with two surface geochemical
indicators: the adsorbed light gaseous hydrocarbons (methane through butane) and the propane-oxidizing bacterial populations
in the soil. The integration of geochemical observations show the occurrence of elevated values in the northern part of the
study area, which is also coincident with the presence of exposed dyke swarms that probably serve as conduits for hydrocarbon
microseepage. The corroboration of iodine with existing geological, geophysical, and geochemical data suggests its efficacy
as one of the potential tool in surface geochemical exploration of hydrocarbons. Our study supports Deccan Syneclise to be
promising in terms of its hydrocarbon prospects. 相似文献
2.
Scholars have long documented widespread aging and depopulation of rural communities in the Great Plains. Paralleling these trends is the emergence, growth, and spatial dispersion of new and longtime non-white populations across the region. The dual processes of population loss in many counties combined with the growth of new, non-white population groups suggest that the ethnic structure of the population is changing. In this article we utilize choropleth maps, Hoover and Simpson indexes, and cluster analysis to assess whether the emergence and growth of ethnic minority groups in the Great Plains between 1970 and 2008 is a localized phenomenon or region-wide shift in the ethnic composition of the population. Results suggest that as depopulation is occurring in many counties of this region, the growth of non-white populations, both immigrant and native born, is changing or restructuring the ethnic composition of the Great Plains. 相似文献
3.
Forest vegetation in the southeastern United States extends westward beyond the Ozark and Ouachita plateaus in Arkansas and Missouri into the Central Plains. Along this transect, luxuriant forests give way to mixed forests and grasslands that include smaller trees and progressively fewer tree species and eventually to grassland‐dominated landscapes in central Kansas, Oklahoma, and Texas. This transition is directly related to decreasing precipitation with distance to the west of the Mississippi River valley. Many species, however, have abrupt western range boundaries related to physiography and hydrogeomorphic processes. The western range limits for many trees correspond to Coastal Plain boundaries that at a regional scale impose sharper range boundaries than would be expected on the basis of decreasing precipitation. Also, riparian habitats within stream valleys extending westward from the Coastal Plain provide suitable habitats for trees in the dry regions of the Great Plains. The presence of riparian trees in this region is determined largely by the presence or absence of groundwater conditions necessary for survival. For floodplain trees, then, it is primarily habitat—not climate—that determines the location of range boundaries. 相似文献
4.
基于2005年和2015年人口数据,运用收缩指数、地统计分析和地理探测器等方法,研究不同地理尺度下黄土高原地区人口收缩现象与地域分异格局,揭示黄土高原地区人口收缩驱动力差异及机理。结果表明:(1)黄土高原地区县级与地级行政单元下人口收缩比例均较高,单一地理尺度识别人口收缩存在偏差。(2)黄土高原地区的人口收缩现象在区域-省-地级市尺度均符合“核心-外围”模式,核心区域(城市)人口集聚,边缘地区(县)人口流失。(3)经济发展水平差异和城乡发展不平衡成为黄土高原地区人口集聚与流失的主要诱因。地级市收缩型主要受城镇化和工业化水平驱动,为城市综合发展能力不足而导致的人口收缩;地级市局部收缩型处在社会-经济高速发展时期,内部要素分配不均导致内部局部收缩。 相似文献
5.
In this study, information is collected on the weather, soils, field management and agricultural statistics in the Bangladesh, India and Myanmar(BIM) region. Crop growth parameters within the EPIC(Environmental Policy Integrated Climate) model are calibrated using cultivar data and regional experimental records of indica hybrid rice Fyou498 and Fengliangyou4 in China. Potential yields of rice are then simulated in the BIM region from 1996 to 2005. The effects of local irrigation and fertilization levels on super hybrid rice yield are examined. The potential yields of Chinese hybrid rice at local irrigation and fertilization levels in 2000 and at full irrigation and rational fertilization levels are found to be 10.22 t/ha and 11.33 t/ha, respectively. The potential for increasing monsoon rice production in the study region is 227.71 million tons. The eastern Indo-Gangetic Plain in India, the southeast coast of India Peninsula and the Ayeyarwady Delta in Myanmar have the largest potentials for monsoon rice production. The northeastern and southwestern areas of the Deccan Plateau and the northwestern region of the Indo-Gangetic Plain need to improve irrigation equipment to meet the water-use requirements of high-yield rice. The central and southern plains in Myanmar and northeastern India need greater access to nitrogen fertilization for high-yield rice. 相似文献
6.
《The Professional geographer》2012,64(1):1-8
The Great Plains is the grasslands of the central United States, but precise delineation of this region has evaded agreement due to the transition between Great Plains grasslands and forests of the eastern United States. After comparing Great Plains delineations in readily available geographic information system layers, I established a northeastern boundary using evidence from historical tree surveys during the 1800s. Additionally, I described tree presence within the Great Plains over time and potential drivers of change. The definition documented here diverges from others by including most of Iowa and part of Illinois, and even small sections in Indiana and Wisconsin, but excluding Missouri due to regular tree presence overall at landscape scales of ecological subsections. In this definition, the Great Plains had an extent of 2.29 million km2 in fifteen states, including Indiana and Wisconsin, and 2.19 million km2 after removal of open forests in Oklahoma and Texas. Tree presence occurs within the Great Plains and tree encroachment is not a new process; however, tree encroachment is increasing in the Great Plains, which causes a decrease in the grasslands region. Nevertheless, clarifying the historical eastern boundary provides a solution to the problem of competing versions of the Great Plains region. Key Words: ecotone, prairie, savanna, tree encroachment. 相似文献
7.
水稻是孟加拉国、印度和缅甸最重要的粮食作物,研究中国超级杂交稻对孟印缅地区的水稻增产潜力,对于保障孟中印缅经济走廊的粮食安全与区域可持续发展具有重要的现实意义。在全面收集孟印缅地区气候、土壤、田间管理信息和农业统计数据的基础上,结合中国籼型杂交稻F优498和丰两优4号的品种信息和区试数据,通过EPIC模型模拟了1996-2005年雨季孟印缅3国在不同情景下的超级稻生产潜力,并分析了孟印缅地区主要胁迫因子对超级稻单产潜力的影响。研究表明：① 中国超级杂交稻在孟印缅地区2000年的灌溉和施肥水平下单产潜力为10.22 t/ha,在充分灌溉且合理施肥的水平下单产潜力为11.33 t/ha。② 孟印缅地区雨季稻的增产空间达22771万t,水稻增产潜力最大的地区是印度的恒河平原东部、印度半岛东南沿海与缅甸的伊洛瓦底三角洲。③ 印度德干高原东北部、西南部和印度大平原西北部需要进一步完善灌溉设备以满足高产水稻用水,缅甸的中南部平原地区和印度的东北地区则需要增施氮肥以满足高产水稻用肥。 相似文献
8.
2000 年来黄土高原地区的人口增长及时空分异 总被引：2，自引：1，他引：1
人口是内容复杂、综合多种社会关系的实体,区域的一切经济社会活动都与人口发展过程密切相关。本文基于长时间序列人口数据,利用模型方法和GIS空间分析技术,从时空结合的角度对黄土高原地区过去2000 年来的人口增长和和时空分异特征进行了较为系统的分析。结果表明:①黄土高原地区人口总量变化受政策、历史事件及社会稳定程度等因素影响较大,历史时期呈现大幅波动,新中国成立后呈平稳增长的态势;②自然条件差异决定着黄土高原地区人口空间分布的基本格局,经济布局、人口政策、技术进步、资源开发等因素对人口分布格局有一定影响,但影响程度相对较小;③1949 年以来,黄土高原地区的人口密度分布格局逐渐形成由东密西疏、南密北疏的半边对半边格局向外围密中间疏的环绕型格局转变的趋势,中心城市的培育和成长是导致人口分布变化的主要原因。 相似文献
9.
鄂尔多斯高原明长城位于明万里长城的中部,是明代边防体系的重要组成部分,明长城的地理位置是当时综合自然-社会-经济诸多因素的结果。在实地考察的基础上,从地貌、气候、农牧业界线三个方面分析了明长城的地理界线意义。明长城一线是鄂尔多斯高原与黄土高原的地貌界线,长城南北地貌类型、地貌特征差异显著。明长城处在中国夏季风的尾闾,是中国季风区与非季风区、暖温带与中温带、半湿润区与半干旱、干旱区的分界线。明代鄂尔多斯高原的长城是农牧业的分野,同时鄂尔多斯高原明长城位于中国农牧交错带中部的中轴位置,明长城两侧生产方式和土地利用显著不同,具有农牧分界线的地理意义。研究结果可加深对明长城价值的认识并促进长城的遗产保护。 相似文献
10.
Xiaobo Wang Shaoqiang Wang Jinghua Chen Huijuan Cui Yijin Wu N H Ravindranath Atiq Rahman 《地理学报(英文版)》2018,28(7):1020-1036
In this study, information is collected on the weather, soils, field management and agricultural statistics in the Bangladesh, India and Myanmar (BIM) region. Crop growth parameters within the EPIC (Environmental Policy Integrated Climate) model are calibrated using cultivar data and regional experimental records of indica hybrid rice Fyou498 and Fengliangyou4 in China. Potential yields of rice are then simulated in the BIM region from 1996 to 2005. The effects of local irrigation and fertilization levels on super hybrid rice yield are examined. The potential yields of Chinese hybrid rice at local irrigation and fertilization levels in 2000 and at full irrigation and rational fertilization levels are found to be 10.22 t/ha and 11.33 t/ha, respectively. The potential for increasing monsoon rice production in the study region is 227.71 million tons. The eastern Indo-Gangetic Plain in India, the southeast coast of India Peninsula and the Ayeyarwady Delta in Myanmar have the largest potentials for monsoon rice production. The northeastern and southwestern areas of the Deccan Plateau and the northwestern region of the Indo-Gangetic Plain need to improve irrigation equipment to meet the water-use requirements of high-yield rice. The central and southern plains in Myanmar and northeastern India need greater access to nitrogen fertilization for high-yield rice. 相似文献
11.
Avery L. C. Shinneman Danuta M. Bennett Sherilyn C. Fritz Jens Schmieder Daniel R. Engstrom Aris Efting John Holz 《Journal of Paleolimnology》2010,44(2):443-464
The Nebraska Sand Hills are a distinctive eco-region in the semi-arid Great Plains of the western United States. The water
table underlying the Sand Hills is part of the High Plains/Ogallala aquifer, an important water resource for the central Great
Plains. Lake levels are affected directly by fluctuations in the water table, which is recharged primarily by local precipitation
and responds quickly to climatically induced changes in regional water balance. Instrumental records are available for only
50–100 years, and paleolimnological data provide important insights into the extremes and variability in moisture balance
over longer time scales. A set of 69 lakes from across Nebraska was used to establish a statistical relationship between diatom
community composition and water depth. This relationship was then used to develop a diatom-based inference model for water
depth using weighted averaging regression and calibration techniques. Development of the inference model was complicated by
strong intra-seasonal variability in water depth and the linkages between depth and other limnologic characteristics, including
alkalinity, water clarity and nutrient concentrations. Analysis of historical diatom communities from eight lakes allowed
for the reconstruction of lake-level fluctuations over the past several thousand years. Comparisons of the more recent portion
of these reconstructions with the instrumental Palmer Drought Severity Index (PDSI) showed that sediment records may not faithfully
reflect short-term fluctuations in water level, except where sedimentation rates are very high. However, large and persistent
changes in moisture availability were discernible even in longer, low-resolution records. Thus, diatoms are a useful addition
to the tools available for understanding past drought in the central Great Plains, especially when trajectories of change
are constrained by data from multiple sites or other proxies. 相似文献
12.
青藏高原人口地域分异规律及“胡焕庸线”思想应用 总被引：8，自引：4，他引：4
青藏高原是中国乃至全球典型的人口稀疏区之一,但内部人口地域分异明显。通过构建青藏高原乡镇街道尺度的人口空间数据集,系统核算青藏高原人口数量及其空间密度,从经度、纬度、极向和垂直4个维度解析青藏高原人口地域分异规律,并基于“胡焕庸线”思想,提出青藏高原的“祁吉线”人口地理划分方案。结论包括：① 青藏高原人口空间分布不均衡,具有“东南密、西北疏”的总体空间分布特征,距离“寒旱核心区”近疏远密的极向地域分异明显;② 青藏高原人口地域分异与海拔、土壤、水资源、气候、植被等自然环境本底具有高度耦合关系,自然因素间交互作用加强了人口地域分异;③ 青藏高原人口地域分异可以通过连接祁连县与吉隆县的“祁吉线”体现,两侧地域面积大致相同,但是东南半壁与西北半壁人口比例达到93∶7的悬殊;④ “祁吉线”长期稳定,但是东南半壁人口持续微降,西北半壁人口持续微增,未来时期,东南半壁依然是青藏高原城镇化及人类活动的主要区域,而西北半壁应当重视人口增长与生态环境压力的矛盾。 相似文献
13.
The American Great Plains is a region dominated by a flat, treeless, semiarid environment that has challenged population settlement for over 140 years. As railroad companies successfully attracted pioneers to settle the land, state governments established hundreds of counties. Following Jeffersonian ideals, many of the counties were small in area so they could better serve the local agricultural‐based population. When states established these counties, they envisioned that the population would continue to grow and the Great Plains would become the breadbasket of North America. Unfortunately that did not materialize. A succession of hardships combined with serious environmental constraints has discouraged large‐scale settlement in the region. Many counties reached their maximum population in the early 1900s and their totals have decreased ever since (in some counties by as much as 60 percent to 80 percent). This has led a number of government officials to consider consolidating counties much like school districts have been combined. Using Logan and Gove counties in western Kansas as a case study, our purpose is to understand how attached people are to the county in which they live. Employing multiple methods, we gathered information about how different segments of the population regard their local county. We learned that changing computer technology and the Internet has the biggest impact on peoples' attachment to the county seat. 相似文献
14.
论文基于黄土高原地区乡镇1980、1990、2000、2010、2016年5期截面数据,利用位序—规模法则和异速标度律,分析了乡镇尺度人口和可达性规模结构、等级体系及异速标度演化关系。结果表明：① 人口规模以中小等级乡镇为主,60%的乡镇人口规模正增长,总体呈“南北高、中间低”分布格局;可达性水平总体呈明显上升趋势,空间上自东南向西北逐渐降低;河谷平原区人口规模和可达性均最大。② 人口和可达性均呈位次型分布,人口位序—规模具有明显双分形结构,由均衡向极化转变;可达性位序—规模以2000年为转折点由双分形演变为单分形,由低水平均衡转向更高水平均衡。③ 3006个乡镇整体以正异速生长为主,负异速生长为辅,黄土高塬沟壑区、河谷平原区内乡镇异速生长类型以人口增长正异速生长为主,黄土丘陵沟壑区、土石山区、沙地和沙漠区内乡镇以人口下降正异速生长为主,农灌区内乡镇异速生长以人口增长正异速一级和人口下降负异速一级为主。最后根据人口和可达性异速类型和空间分布特征,提出各分区发展的建议。 相似文献
15.
正负地形可通过源汇过程对水、土资源进行再分配,影响山区的人口分布。获取正负地形数据,运用6个指标和多元逐步回归法,分析贵州高原山区正负地形特征及其对人口分布的影响。研究表明：①贵州高原山区的正负地形结构异质性明显。蚕食度、深切度、平均粗糙度比、形状指标、匀度指数、破碎度的平均值分别为1.07、371m、1.01、3.40、325和3.34,表明正地形被负地形蚕食明显、切入深度大,正、负地形的粗糙度基本相当,正负地形景观斑块呈现形状不规则、面积不均匀的破碎状态。6个正负地形指标中,匀度指数的变异性最大,变异系数为90.43%;平均粗糙度比的变异性最小,变异系数为1.06%;②贵州高原山区的人口分布不均匀性突出。人口累积达到40%时,累积面积百分比为14%;人口累积达到80%时,累积面积百分比约为50%;③6个正负地形指标中,蚕食度和深切度是影响人口分布的主要因素。蚕食度与人口密度呈正相关关系,深切度与人口密度呈负相关关系。研究成果为研究地形条件的人口影响提供补充,并为贵州高原山区人-地关系协调和土地可持续管理提供参考。 相似文献
16.
The agricultural regional type and function are the key theoretical issues in agricultural geography research. Gully agriculture in the Loess Plateau is a new regional type of agricultural system with the coupling development of the modern gully human-earth relationship. The study of its functional changes is of great practical significance for food security, rural revitalization and sustainable development of regional agriculture in the region of interest. This paper analyses the multifunctional change of gully agriculture in the Loess Plateau and its dynamic mechanism by using large-scale remote sensing data, topographic relief amplitude model, and spatial econometric model to understand internal implications for evolution differentiation at the basin level. The results show that: (1) The spatial concentration of production and supply function of agricultural products (APF) in the gully of the Loess Plateau gully is high, while the ecological conservation and maintenance function (ECF), employment and social security function (ESF), cultural heritage and leisure function (CRF) are relatively low. The four functions’ spatial distribution has revealed an apparent regularity. (2) APF has been significantly enhanced, which is mainly distributed in point clusters and strips in the farming and pastoral areas in northern Shaanxi to the Yanhe river basin. The high-value areas of ESF are clustered around the urbanized metropolitan circles and urban-rural staggered areas along the Great Wall. ECF is concentrated in areas with significant natural endowments and excellent ecological conditions. CRF is significantly higher in the municipal districts and the surrounding regional central cities. (3) There are noticeable differences in the gully agriculture regional function (GARF) evolution process due to the geographical environment and socio-economic development stages. In this regard, natural factors have tremendously affected APF, ESF, and ECF, while socio-economic factors greatly differ in the four functions. There are still differences in the driving mechanisms of modern gully agriculture evolution types; hence many critical policies in the Loess Plateau can directly affect the function evolution paths. The dynamic evolution of GARF can reflect the general law of rural human-earth system transition in gully areas, thereby providing policy ideas for high-quality development of agriculture in the Loess Plateau. 相似文献
17.
Offshore Extension of Deccan Traps in Kachchh,Central Western India: Implications for Geological Sequestration Studies 总被引：1，自引：0，他引：1
The Deccan basalts in central western India are believed to occupy large onshore–offshore area. Using geophysical and geological
observations, onshore sub-surface structural information has been widely reported. On the contrary, information about offshore
structural variations has been inadequate due to scarcity of marine geophysical data and lack of onshore–offshore lithological
correlations. Till date, merely a few geophysical studies are reported that gauge about the offshore extent of Deccan Traps
and the Mesozoic sediments (pre-Deccan). To fill this gap in knowledge, in this article, we present new geophysical evidences
to demonstrate offshore continuation of the Deccan volcanics and the Mesozoic sediments. The offshore multi-channel seismic
and onshore–offshore lithological correlations presented here confirm that the Mesozoic sedimentary column in this region
is overlain by 0.2–1.2-km-thick basaltic cover. Two separate phases of Mesozoic sedimentation, having very distinctive physical
and lithological characteristics, are observed between overlying basaltic rocks and underlying Precambrian basement. Using
onshore–offshore seismic and borehole data this study provides new insight into the extent of the Deccan basalts and the sub-basalt
structures. This study brings out a much clearer picture than that was hitherto available about the offshore continuation
of the Deccan Traps and the Mesozoic sediments of Kachchh. Further, its implications in identifying long-term storage of anthropogenic
CO2 within sub-basalt targets are discussed. The carbon sequestration potential has been explored through the geological assessment
in terms of the thickness of the strata as well as lithology. 相似文献
18.
The Ogallala Formation of Miocene/Pliocene age is present over a large area of the Great Plains in the central US. The formation is composed of mostly clastic material eroded and transported eastward from the Rocky Mountains by eastward flowing rivers and streams. It contains the life-giving water that supports the population and farming activities of this vast area. However, this precious water resource is fast being depleted. The geology and geologic history, groundwater recharge, irrigation development, and water law and management of the region are outlined so as to highlight the nature and extent of the water problems facing that region and point to a more sustainable path. Further strengthening local water management and coordination with state government as well as better interstate coordination of the High Plains states will help sustain this critical water resource for generations to come. 相似文献
19.
基于GIS的青藏高原人口统计数据空间化 总被引：93，自引：6，他引：87
根据2000年第5次全国人口普查数据分析,西藏、青海2省区各市县平均人口密度与海拔高度、土地利用、主要道路有较强的相关关系,河流水系对居民点分布的影响较为明显,而居民点是人口分布的重要指示因子。以GIS软件为工具,通过较为客观的方式赋予各影响因子人口分布影响权重,运用多源数据融合技术进行了人口统计数据的空间化。结果显示,通过数据融合产生的人口密度与各市县实际人口密度的相关系数大于0.80,与试验区各乡镇的实际人口密度的相关系数大于0.75。最终生成的栅格人口密度数据既与各市县统计型人口数据保持一致,又反映了各市县内部人口分布的空间变化。 相似文献
20.
美国荒野风景河流体系是全球最早建立的河流保护地类型。经过50年发展,其完善的体系呈现出一定空间分布特征。将线状国家荒野风景河流（NWSR）抽象为点状单元,对208个NWSR单元进行空间计算,并与自然生态和社会经济等因素进行叠加分析。结果表明,美国已有40个州分布NWSR,其中以俄勒冈等3个州的数量分布最多,且集中分布于特定的区域：西部的太平洋海岸、落基山脉和山间高地3个自然地理区;极地、温湿润、干旱3个Ⅰ级生态区;太平洋西北部、加利福尼亚、阿拉斯加及五大湖4个流域。NWSR线密度与州域的人口密度、经济水平相关性不强,但与大坝建设密切相关。荒野思想影响了法案制定,法案指导了遴选标准,遴选标准又进一步影响了NWSR的空间分布。研究对中国的借鉴意义在于：应当明确保护地指导思想、关注价值突出区域、确定合适遴选标准、重视保护地系统规划等。 相似文献