共查询到20条相似文献，搜索用时 328 毫秒
1.
应用高空间分辨率的网格逐日气象数据,根据国家集中供暖有关设计规范定义了集中供暖气候指标,分析了气候变暖对中国集中供暖气候指标的影响。结果表明：近55 a来中国集中供暖初日均呈后延趋势,初日特征线年代际南北移动较小。供暖终日均呈提前趋势,终日特征线在110°E以东地区南北移动较大,2000年以来终日特征线较20世纪60年代北抬了200~300 km。供暖期长度均呈减少趋势,东北、华北地区近55 a减少了10~15 d,西北地区减少了15~20 d;东北、华北、西北地区供暖强度分别减少了12%、20%、15%。从1991~2015年冬季气温变化来看,东北地区最冷冬季与最暖冬季的温度相差可达6.2℃,对供暖强度的影响可达28.9%,华北和西北地区冬季气温最大变幅分别为3.7℃、3.3℃,对供暖强度的影响分别为26.8%和17.6%。气候变暖对中国集中供热气候指标产生了显著的影响。供热部门应该根据天气变化来安排供暖,同时还要注意气候变暖背景下极端冷事件的发生,保证集中供暖安全运行。 相似文献
2.
Mohamed Yousif Takashi Oguchi Katsuro Anazawa Takeshi Ohba 《Natural Resources Research》2014,23(4):423-445
The present study demonstrates the potential of the geospatial information as well as isotopes and chemical analyses to elucidate the hydrogeological setting of the study area. The main objective of this research is to identify factors affecting the occurrence and quality of groundwater in the study area. The Ras Alam El Rum is the pilot area chosen in the northwestern coast of Egypt to evaluate the carbonate aquifer with emphasis on the Middle Miocene aquifer, which has been explored recently. The average of annual precipitation and surface runoff amounts were estimated to indicate possibility of groundwater recharge, where the water-bearing rocks are mainly fractured. The isotope data indicate that the groundwater was derived from rainwater, the recharge source is local precipitation, and no indication of seawater intrusion was recorded. The salinity of the groundwater is attributed to interaction between the water and aquifer rocks represented by limestone, dolomitic limestone, and marl. The mineral indices obtained from the geochemical model reveal that the groundwater is over-saturated with aragonite, calcite, dolomite, strontianite, and barite. The hydrogeological evaluation of the study area led to recommendations to determine of the suitable areas for exploration of the Middle Miocene aquifer and to protect groundwater from deterioration. 相似文献
3.
基于遥感的江苏省大陆岸线岸滩时空演变 总被引：2，自引：0，他引：2
基于江苏省1984-2016年61景多源遥感影像数据和部分实测潮位、坡度数据,利用遥感技术结合改进的水边线方法提取了多时相的海岸线和平均大潮低潮线,研究了江苏省绣针河口至连兴河口大陆岸线岸滩的时空演变特征。结果表明：1984-2016年,由于海岸带开发,江苏省的海岸线整体以向海推进为主,自然岸线由458.24 km逐渐减少至166.74 km,人工岸线由163.66 km快速增加至598.74 km,大陆岸线长度由621.90 km增加至765.48 km。发生位置和长度变化的岸段中,淤长岸段长127.62 km,年均向海推进83.03 m;围垦岸段长401.21 km,年均向海推进87.63 m;冲刷岸段长71.17 km,年均离海后退10.81 m;围垦被侵蚀岸段长25.95 km,年均离海后退8.64 m。海岸线的空间变化导致江苏省沿海陆地面积净增加104332 hm2,其中由于围垦增加的陆地面积98520 hm2,围垦是陆地面积增加的主要原因。海岸线的离海后退主要发生在废黄河三角洲岸段,但是到2008-2016年,岸线的侵蚀范围已向南扩大至新洋河口至斗龙港岸段。受围垦活动及岸线侵蚀影响,江苏省潮间带坡度不断变陡,统计断面的平均坡度由1.4‰增加至1.9‰,其中废黄河三角洲岸段的中山河口至扁担河口岸段坡度最陡,基本在3~14‰之间;辐射沙洲陆岸岸段坡度最为平缓,但坡度也在逐渐陡化,由0.9‰增加至1.5‰。潮间带面积由271747 hm2减少至168645 hm2,减幅38%;潮间带平均宽度由5064 m减少至3096 m,减幅39%。 相似文献
4.
Hans Olav Bråtå 《Norsk geografisk tidsskrift. Norwegian journal of geography》2017,71(5):301-312
The aim of the article is to analyse challenges facing the commercial production of historical beers, which are ‘extinct’ beers. The concept of ‘fictive terroir’ is introduced to emphasize these challenges. The author addresses the following questions: What kind of knowledge is needed to produce historical beers? How can this knowledge be acquired? How can it be used commercially in craft breweries? The studied case is Vossaøl, a craft beer imitation of a beer produced in the early 19th century. The data were obtained from written sources and interviews with local home brewers and brewers at Voss Brewery in Norway. The study revealed the need to reconstruct the terroir in the early 19th century. Additionally, Voss Brewery had to acquire knowledge about how to process and combine the ingredients, which included the traditional yeast (kveik). Involving traditional home brewers was crucial to determine how ingredients could be combined to produce Vossaøl. The author concludes that a synthetic knowledge base was a useful point of departure in this respect. Participation in the traditional culture of brewing proved an important means when working with this knowledge base. The results are interesting in the broader context of the reconstruction of beverages and food. 相似文献
5.
青藏铁路察尔汗盐湖段风沙活动特征 总被引：2，自引：2，他引：0
研究青藏铁路沿线的风沙活动特征,可以为认识高原铁路风沙危害的形成机理、建立完善有效的护路防沙体系提供参考。在实地考察风沙地貌的基础上,架设测风塔获取风况信息,采集了沙丘表层沉积物样品,对铁路沿线察尔汗盐湖段的风动力条件、沙丘沉积物粒度特征和沙丘形态特征进行了分析。结果表明：（1）研究区域年平均风速为3.7 m·s-1,风速最大值出现在春季。起沙风以WNW方向为主,属于中风能环境,低风向变率,宽单峰型风况。合成输沙方向（298.14°）与铁路走向（208.86°）垂直相交。稳定的西北风、风沙流与铁路线路走向垂直的风况特征是青藏铁路沙害形成的动力条件。（2）沉积物以中沙、细沙为主,但细沙组分占优;分选性较好,粒径分布表现出与铁路线越近、颗粒越粗的规律。粒径0.063~0.04 mm的沙粒为青藏铁路风沙危害提供了物质条件。（3）铁路线两侧沙丘分布特征及变化指示该路段风沙活动强烈,现有防沙体系退化严重,风沙危害日益突出。 相似文献
6.
科尔沁沙地近水区域土地利用及沙漠化时空过程研究——以奈曼旗为例 总被引：3，自引：2，他引：1
以奈曼旗的西湖和舍力虎水库周边10 km范围区域为研究地,以1987年至2007年期间5个年份的Landsat TM影像为基本数据源,按与水体的空间距离,对近水区域各类土地利用面积百分比进行分地带统计。该过程通过ArcGIS平台下的缓冲区分析完成。结果表明,近水区域的土地利用活动和沙地分布的空间差异性十分显著。结果显示:①近水区域土地利用空间分布受地表水资源分布影响显著,在1~6 km范围以内,耕地面积百分比与到水体的距离呈正相关,草地、沙地面积百分比与到水体的距离呈负相关;②各类土地利用类型面积年际变化明显,草地面积百分比呈波动性降低,耕地面积百分比逐年上升,林地面积百分比在1999年后明显比1999年以前有所增加,沙地面积百分比在1999年以前呈现逐年升高的趋势,在1999年以后迅速降低;③土地利用活动的变异程度对近水区域沙地空间分布具有重要影响,二者具有明显的线性相关性。越靠近水体,土地利用活动的年际变化越频繁,导致过垦、过牧的可能性越高,沙地面积百分比越高。 相似文献
7.
荒漠河岸胡杨(Populus euphratica)树干液流的时滞效应 总被引：1，自引：0，他引：1
以2012年4—9月树干液流速率与环境因子的实测数据,分析了荒漠河岸胡杨(Populus euphratica)树干液流的时滞效应。结果表明:不同月份胡杨树干液流速率对不同环境因子的时滞不同;4—9月,胡杨树干液流速率峰值时间比太阳辐射峰值时间晚约1h,比空气温度峰值时间早约1h,比水汽压差峰值时间早约2h,比空气相对湿度谷值时间早约2h;对影响胡杨树干液流速率的环境因子进行了主成分分析,发现胡杨树干液流速率与1h以前的第1主成分、第2主成分相关性最高,相关系数分别为0.864、0.875;对错位前后胡杨树干液流速率与环境因子进行多元线性回归分析发现,在胡杨树干液流的数值模拟中,考虑液流相对于环境因子的时滞效应可以提高模型的拟合精度。 相似文献
8.
以CNKI网络资源共享平台为文献获取平台,运用文献计量分析法分析了中国瘟疫研究的现状和进展。结果表明：过去60年间,在学科领域方面,研究内容涉及的学科领域越来越广,已涉及12大学科门类;其中以历史学领域研究上升速度最快,学科之间差距悬殊。在研究时间方面,研究时段以现代为主;时间维度以断代史为主,自古及今的“大历史观”研究相对较少,总比不足1.0%。在研究区域方面,研究区域重视全国范围和国外地区的研究;研究深度已涉及村镇尺度的研究;国内省区研究空间差异显著,研究热点区―冷点区呈东部沿海向内陆递减趋势。 相似文献
9.
中国西北干旱内陆河流域分布式出山径流模型 总被引：1，自引：0，他引：1
In order to predict the futuristic runoff under global warming, and to approach to the effects of vegetation on the ecological environment of the inland river mountainous watershed of Northwest China, the authors use the routine hydrometric data to create a distributed monthly model with some conceptual parameters, coupled with GIS and RS tools and data. The model takes sub-basin as the minimal confluent unit, divides the main soils of the basin into 3 layers, and identifies the vegetation types as forest and pasture. The data used in the model are precipitation, air temperature, runoff, soil weight water content, soil depth, soil bulk density, soil porosity, land cover,etc. The model holds that if the water amount is greater than the water content capacity, there will be surface runoff. The actual evaporation is proportional to the product of the potential evaporation and soil volume water content. The studied basin is Heihe mainstream mountainous basin, with a drainage area of 10,009 km^2. The data used in this simulation are from Jan. 1980 to Dec. 1995, and the first 10 years‘ data are used to simulate, while the last 5 years‘ data are used to calibrate. For the simulation process, the Nash-Sutcliffe Equation, Balance Error and Explained Variance is 0.8681,5.4008 and 0.8718 respectively, while for the calibration process, 0.8799, -0.5974 and 0.8800 respectively. The model results show that the futuristic runoff of Heihe river basin will increase a little. The snowmelt, glacier meltwater and the evaportranspiration will increase. The air temperature increment will make the permanent snow and glacier area diminish, and the snowline will rise. The vegetation, especially the forest in Heihe mountainous watershed, could lead to the evapoWanspimtion decrease of the watershed, adjust the runoff orocess, and increase the soil water content. 相似文献
10.
ZHAO Jingbo 《地理学报》2005,15(4):475-483
On the basis of the geomorphology, paleosol, paleoclimate and loess age, major changes of the Loess Plateau were studied. There are five major changes in the evolution of the Loess Plateau in China. Among them, the first, second, third and fourth major changes have taken place since the formation of the Loess Plateau, and the fifth major change will happen in 100 years. The first major change, which occurred at about 2.50 Ma BP, was a transition from red earth plateau to the Loess Plateau, and reflects the climate from the warm-sub-humid to the alteration between cold-and-dry and warm-and-humid. The driving force of this first major change was climate. The second major change, which took place at about 1.60 Ma BP, was a vital transition of the main rivers in this area from non-existence to existence, and represented an important change on the Loess Plateau's neotectonic uplift from the slow rising to periodically accelerated rising, and making the river's erosion go from feeble to strong. The driving force of the second major change is tectonic uplift. The third major change which occurred at about 150 ka, was a great transition of the Yellow River's inpouring from a lake outlet to a sea outlet. At that time, the Yellow River cut the Sanmen Gorge. The transition led to the transformation of loess material from internal transportation to external transportation. The driving force of the third major change was running water erosion. The fourth one that occurred at about 1.1 ka was a change of the Loess Plateau from natural erosion to erosion accelerated by human influences. The driving force of the fourth major change is mainly human activities. The fifth major change, which is the opposite change to the fourth one, in which the motive power is human activity, too. 相似文献
11.
Baseflow is an important component of river or streamflow. It plays a vital role in water utilization and management. An improved Eckhardt recursive digital filter(IERDF) is proposed in this study. The key filter parameter and maximum baseflow index(BFImax) were estimated using the minimum smoothing method to improve baseflow estimation accuracy. The generally considered BFImax of 0.80, 0.50 and 0.25 according to the drainage basin's predominant geological characteristics often leads to significant errors in the regions that have complex subsurface and hydrologic conditions. The IERDF improved baseflow estimation accuracy by avoiding arbitrary parameter values. The proposed method was applied for baseflow separation in the upstream of Yitong River, a tributary of the Second Songhua River, and its performance was evaluated by comparing the results obtained using isotope-tracer data. The performance of IERDF was also compared with nine baseflow separation techniques belonging to filter, BFI and HYSEP methods. The IERDF was also applied for baseflow separation and calculation of rainfall infiltration recharge coefficient at different locations along the Second Songhua River's mainstream for the period 2000–2016. The results showed that the minimum smoothing method significantly improved BFImax estimation accuracy. The baseflow process line obtained using IEDRF method was consistent with that obtained using isotope 18 O. The IERDF estimated baseflow also showed stability and reliability when applied in the mainstream of the Second Songhua River. The BFI alone in the river showed an increase from the upstream to the downstream. The proportion of baseflow to total flow showed a decrease with time. The intra-annual variability of BFI was different at different locations of the river due to varying climatic conditions and subsurface characteristics. The highest BFI was observed at the middle reaches of the river in summer due to a water surplus from power generation. The research provided valuable information on baseflow characteristics and runoff mode determination, which can be used for water resources assessment and optimization of economic activity distribution in the region. 相似文献
12.
Geographical data sets sometimes contain missing observations that need to be estimated. A statistical approach to the problem is discussed for multivariate normal spatial data sets satisfying the first-order spatial Markov property with constant mean, where the information at neighboring or contiguous observed sites is used to estimate the missing values. The completed data are used to estimate the parameters of the distribution. The procedure is iterative. The approach is a special case of the Orchard and Woodbury missing information principle. The paper concludes with an illustrative empirical example using rainfall data from an area of Kansas and Nebraska. The quality of the estimates for different sites are compared. 相似文献
13.
吉林省西部沙化土地持续农业体系建立的实践 总被引：2，自引：1，他引：2
吉林省沙化土地的８７．９％分布在吉林省西部白城、松原半干旱地区，统属科尔沁和松嫩沙地，面积９２１６．５ｋｍ２，占吉林省西部总面积的１９．６％。８年（１９８６年～１９９３年）实践证明：针对沙地环境特点建立的“乔、灌、草”、“果、药、杂”、“田、林、草”为主体的三种持续农业体系效果明显。 相似文献
14.
基于遗传算法自动获取CA模型的参数 总被引：11，自引：1，他引：10
本文提出了基于遗传算法来寻找CA模型最佳参数的方法。CA被越来越多地应用于城市和土地利用等复杂系统的动态模拟。CA模型中变量的参数值对模拟结果有非常重要的影响。如何获取理想的参数值是模型的关键。传统的逻辑回归模型运算简单,常常用来获取模型的参数值,要求解释变量间线性无关,所以获取的城市CA模型参数具有一定的局限性。遗传算法在参数优化组合、快速搜索参数值方面有很大的优势。本文利用遗传算法来自动获取优化的CA模型参数值,并获得了纠正后的CA模型。将该模型应用于东莞1988~2004年的城市发展的模拟中,得到了较好的效果。研究结果表明,遗传算法可以有效地自动获取CA模型的参数,其模拟的结果要比传统的逻辑回归校正的CA模型模拟精度高。 相似文献
15.
黄土台塬区土地利用转移流及空间集聚特征分析 总被引：17，自引：1，他引：16
提出了土地利用转移流和土地利用活跃度的概念,基于Landsat 遥感影像数据,采用土地利用变化测度模型,以5 年和25 年两种时间尺度对黄土台塬区土地利用时空动态特征进行分析,并将密度制图法应用到土地利用变化的空间集聚特征识别中.研究表明：① 黄土台塬区耕地占绝对优势,后备耕地资源严重不足,林地、草地、水域比例较低,存在较大生态风险;② 耕地与建设用地、草地、林地之间的转移关系是黄土台塬区土地利用转移的关键关系,决定着台塬区土地利用变化特征;③ 1985-2010 年耕地转建设用地流高达26668.80 hm2,占土地转移流40.75%,草地转耕地流18923.90 hm2,占28.91%,建设占用耕地情况严重,耕地占补平衡主要通过挤占草地实现;④ 25 年以来,土地利用变化对水域扰动最大,其次为森林,草地第三;⑤ 土地利用变化存在阶段性,1990-2000 年土地利用变化速率高于其他时段;⑥不同时间尺度下土地利用变化的空间集聚特征不同,25 年尺度下城镇附近土地变化幅度较高,5 年尺度下土地利用变化热点区由台塬中部向东西边缘区推移. 相似文献
16.
中外区域政策对比研究 总被引：11，自引：3，他引：8
区域干预包括区域分工与协作受阻和区域差异扩大两个方面.发达国家主要面临的是空间差异扩大的区域均衡问题,其区域政策都是在经济发展达到一定的水平[人均GDP达500多美元(二、三年代当年价)]时制定和实施的,中央财政用于区域均衡政策的经费一般占到10-30%.我国区域政策面临区域发展和区域均衡双重任务.“九五”及到2010年期间,我国区域政策的总原则应该是效率优先、兼顾均衡.主要措施是加快空间一体化市场的建设,做到产业政策与区域政策相结合,适当加大扶贫工作的力度. 相似文献
17.
东北地区资源型城市转型过程中社会—经济—环境协调演化特征 总被引：2，自引：1，他引：1
借鉴协调发展相关理论,构建综合评价资源型城市社会、经济和环境转型的指标体系,利用面板数据回归模型测算2000-2014年系统内各要素对资源型城市协调转型的作用,对东北地区资源型城市转型以来协调发展的时空格局进行分析。研究发现：① 东北地区资源型城市转型协调水平呈现波动式缓慢上升的走势,共出现四次较大幅度的波动,空间上差异性先减弱后加剧,协调程度较高的地区主要集中在辽宁省南部,失调城市分布在黑龙江省北部边缘地区,无论是协调度水平变化或是空间分布上这种“两极”分化的趋势越来越明显。② 东北地区资源型城市协调转型发展总体水平不高,从划分类型看,协调发展型城市在社会—经济—环境各方面作用力均衡较好,对社会服务设施完善等方面投入强于发展调和型城市和失调衰退型城市,钢铁型城市协调转型水平强于石油型城市和冶金型城市,森工型城市表现最弱。③ 第三产业发展、教育、技术、非国营经济、生产生活环境等因素对协调转型的促进作用显著,但历史遗留问题、产业结构升级等仍待进一步解决,同时也对实践创新、体制机制改革提出了高要求。 相似文献
18.
基于2012—2017年全国《中国卫生和计划生育统计年鉴》数据,采用空间自相关分析等方法,刻画中国居民食源性疾病的空间分布格局及其变化,并采用空间滞后面板回归模型（SLM）和时空地理加权模型（GTWR）,识别影响食源性疾病空间分布的主要因素及其变化。结果表明：（1）中国食源性疾病分布具有不均衡性,总体趋势为集中分布于南部以及沿海地区,五年间集中区已出现明显的向北移动的趋势;（2）中国食源性疾病事件数具有一定的空间集聚特征,五年间空间集聚下降。高-高类型区主要分布于西南地区,而低-低类型区集中分布于中国北部。2011—2016年,中国食源性疾病变化趋势与空间分布特征类似;（3）空间滞后面板回归模型分析结果表明,食源性疾病事件具有显著的空间溢出效应。人口密度、突发环境事故的增加将使得食源性疾病增加,而政府财政投入、居民教育水平、城镇化、环境质量的提高将使得食源性疾病减少。除居民教育水平外其余变量也均具有显著的空间溢出效应;（4）时空地理加权模型分析结果表明,食源性疾病的影响因素存在空间差异。地区人口密度对食源性疾病的相对压力由东向西加大。政府财政投入对食源性疾病的降低作用由东南部沿海地区向其余地区递减。居民教育水平提高对食源性疾病降低作用由中部向东西逐步加大。城镇化率对食源性疾病降低作用由东南部沿海地区向其余地区递减。环境质量对食源性疾病降低作用由东南部沿海地区向其余地区递增;突发环境事故对食源性疾病的相对压力由中部向东西加大;年平均气温对食源性疾病的相对压力由南向北减小;年平均降雨量对食源性疾病的相对压力由东部沿海地区向西部内陆地区减小。 相似文献
19.
岱海地区原始农业文化的兴衰与环境演变的关系 总被引：2，自引：6，他引：2
内蒙古中南部岱海地区考古学文化的发展受到环境条件的制约。原始农业文化的兴起与发展对应于全新世暖期的暖湿条件;农业文化的间断、南移与由农向牧的转变与4～35kaBP发生的变冷、变干的突变事件相对应;而原始农业文化阶段中间每一次文化的间断、侵入、融合总是可以在气候变化中找到相应的变化阶段,与短期寒冷事件的开始或结束对应。 相似文献
20.
赵景波 《地理学报(英文版)》2005,15(4):475-483
1 Introduction W hatim portanttransform ations have taken place during the form ation ofthe Loess Plateau in China? Research on this problem has especially im portantscientific significance forus to learn ofthe evolution oftheLoessPlateau and predictthe f… 相似文献