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为研究西北非湿润区气候特征和毛细阻滞覆盖层高危易渗气象段,掌握该地自然气候条件下引发毛细阻滞覆盖层渗漏的气象机制,总结分析了西北干旱、半干旱气候区50年的降水、蒸腾蒸发和温度等气候特征。在西北某填埋场开展了毛细阻滞覆盖层足尺极端降水试验,验证了覆盖层在极端偶然降水事件下的防渗储水性能。耦合气候条件开展了土质覆盖层长期防渗性能分析,鉴别筛选出了西北干旱、半干旱气候区诱发渗漏的高危气象段,揭示了高危易渗气候段引发渗漏的气象机制。结果表明：（1）西北干旱、半干旱气候区4-11月降水多,12月-次年4月降水少,冬干夏湿,雨-热同期,利于土质覆盖层水分的存储-释放。（2）西北非湿润区极端偶然连续强降水量阈值在56.1～118.5mm之间,现场覆盖层极端降水试验累计降水量194.85 mm,土层存储量148.22 mm。在该区极端偶然连续强降水条件下毛细阻滞覆盖层能满足防渗标准。（3）长期服役中西北干旱和半干旱气候区,8-11月是毛细阻滞覆盖层的高危易渗气象段,11-12月次之,1-7月渗漏可能最低。该气候区土质覆盖层防渗设计和填埋场运营-管理-维护工作中,8-11月为关键气象段,建议进行重点校核... 相似文献
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蒸发蒸腾覆盖层相比传统覆盖层有许多优势,目前这种覆盖层主要应用于干旱和半干旱地区,但研究湿润地区垃圾填埋场蒸发蒸腾覆盖层的水分运移规律和工作性能很有必要。通过二维饱和-非饱和模型,分析覆盖层厚度、土壤类型、植被条件、气候条件等设计参数对蒸发蒸腾覆盖层防渗性能的影响,并对覆盖层中的水分运移规律及其工作性能和适用性进行研究。研究结果表明,随着覆盖层厚度和叶面积指数LAI增加,蒸发蒸腾覆盖层的最终透水量（穿过覆盖层水分）呈减小趋势,但覆盖层厚度和叶面积指数较大时透水量减小趋势不明显;拥有较大储水能力和适当渗透系数的覆盖层能够有效地减少透水量;降雨的季节性分布对蒸发蒸腾覆盖层性能有很大影响,当多雨期与高温期分布一致时,蒸发蒸腾覆盖层的性能可满足设计要求;在非饱和条件下,毛细阻滞型覆盖层利用粗-细粒土之间水力特性的差异形成毛细阻滞效应减少水分向下入渗,其防渗性能优于单一土层型覆盖层,但在不利气象条件组合下,该毛细阻滞作用可能失效, 其防渗性能将大大下降。 相似文献
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我国黄土以分布最广、厚度最大、地层最完整而著称世界,主要分布在陕、甘、宁、晋、豫等北方干旱、半干旱地区,面积约35万平方公里。由于干旱少雨,水源不足,农业发展受到一定限制。该区水文地质条件独特,正确评价和合理开发利用地下水资源,对广大黄土地区经济发展和提高人民生活水平,具有重要的实际意义和理论价值。本文根据作者于1984年在“全国黄土及黄土区应用地质学术讨论会”上的发言稿整理撰写。一、关于黄土水基本特征及其含水组划分黄土区地下水基本特征,主要受气候、地貌、岩性、古地理和堆积环境等因素所制约。因含水介质、渗透场及其排泄出露条件不同,黄土水具如下基本特征。 相似文献
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黄土的显微结构与古气候的关系 总被引：14，自引：2，他引：14
黄土的显微结构特征是黄土粉尘物质堆积之后在特定气候条件和特定自然地理环境中形成的。我国黄土高原晚更新世黄土的显微结构特征反映出晚更新世黄土形成时西北部干旱而东南比较湿润的气候状况,与现今高原区的气候环境区域性变化相一致。根据黄土的显微结构特征,并考虑到黄土的主要化学成分以及磁化强度,黄土高原区晚更新世黄土自西北而东南可以划分为呈逐渐过渡关系的弱风化成土黄土、中等风化成土黄土、较显著风化成土黄土和显著风化成土黄土,它们分别是在干旱、半干旱、半干旱—半显润和半湿润的气候环境中形成的。 相似文献
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50 a来我国干湿气候界线的空间变化分析 总被引：12，自引：1，他引：12
采用干燥度指数为干湿气候区的划分标准, 通过近50 a来年降水量干湿气候界线与干燥度干湿气候界线变动对比分析, 结果表明: 在气候变暖, 降水区域差异性显著的情况下, 我国干旱/半干旱分界线与半干旱/湿润分界线也表现出显著的区域差异性, 且具有"U型"分布特征. 在东北北部, 250 mm年雨量线为干旱/半干旱分界线, 450 mm年雨量线为半干旱/湿润分界线, 半干旱气候向西退缩, 范围缩小; 在东北南部、华北区与河套地区, 300 mm年雨量线为干旱/半干旱分界线, 700 mm年雨量线作为半干旱/湿润分界线, 干旱气候与半干旱气候向东南方向扩展, 空间范围在扩大, 成为"U型"分布的凸出部位; 在西南区与河套以西的西北东部, 250 mm年雨量线为干旱/半干旱分界线, 500 mm年雨量线为半干旱/湿润分界线, 干旱半干旱气候变化不大. 决定我国干湿气候界线空间变化的主要因素是由西太平洋副热带高压位置与强度导致的东南季风、孟加拉弯暖流所导致的西南季风以及西风环流等综合作用的降水量的区域差异性. 相似文献
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通过洛川剖面和白草塬剖面末次间冰期以来黄土古土壤容重序列的建立,对比磁化率、粒度及深海氧同位素分析发现,六盘山东西两侧不同气候区黄土古土壤具有不同的容重值,其成因亦不同。六盘山以东半湿润半干旱气候区黄土古土壤容重值受成壤作用影响,主要由夏季风控制;而六盘山以西半干旱气候区容重值受沉积物粒度影响,主要受冬季风控制。并且在空间上自黄土高原西北向东南容重值呈变大趋势。 相似文献
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植被状况指数的改进及在西北干旱监测中的应用 总被引：8，自引：0，他引：8
干旱是全球分布最广、发生频率最高、持续时间最长、影响范围最大、造成的经济损失最为严重的一种自然灾害，干旱也是所有自然灾害中影响因子最为复杂、人类了解最少、监测最为困难的一种自然灾害，干旱监测是世界性的难题。干旱可以发生在任何气候带上，但干旱、半干旱地区是全球干旱灾害发生最频繁的地区。干旱发生特征和规律因地区的不同会有很大的差异，不同地区对干旱监测方法不同。目前，世界各国干旱监测主要利用基于气象、水文、农业和卫星遥感等观测资料建立的各种干旱指数开展，已经有150多种干旱指数。植被状况指数VCI是应用最为广泛的一种卫星监测干旱的指数，研究和业务应用结果表明，VCI对全球各地的干旱均有较好的反映，已经应用在美国国家大气海洋局（NOAA）日常干旱监测业务中，中国国家卫星气象中心干旱卫星遥感监测服务产品也是以VCI为基础。
我国干旱半干旱地区主要分布在新疆、甘肃、青海、陕西、宁夏以及内蒙古自治区的中西部，这里降水少且不稳定，降水变率大，是中国干旱发生频率最高的地区。干旱严重制约着当地经济发展和人类生活质量的提高，使本身非常脆弱的生态环境趋于恶化。为了了解条件植被指数VCI对西北地区不同气候区干旱的监测能力，以上述6省（区）为研究区，利用1982—2003年22年NDVI数据，计算了研究区域22年来逐月的VCI，对比分析了不同气候区VCI与降水距平的关系。结果表明，VCI在空间和时间上较好地反映了西北大部分气候干旱发生、发展和空间分布，是干旱监测的较好指标，但在干旱和极端干旱地区，VCI经常出现异常偏高现象，不能反映干旱气候区常年干旱的基本特点。通过对西北不同生态系统之间NDVI特点和各生态系统间NDVI年变化及其年际变化规律的研究，设计了VCI改进方案，提出了改进的条件植被指数RVCI。通过对22年来逐月RVCI与VCI的对比，RVCI客观地反映了干旱气候区常年干旱特点，较VCI有显著改进。
相似文献
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《地学前缘》2017,(1):106-142
以古生物学和沉积学资料为主,结合地球化学和植物化石气孔器参数等资料系统分析了中国侏罗纪的气候特征、气候分区及其演变过程。侏罗纪时期的气温明显比现代为高,但无论是温度还是湿度都经历了强烈的变化,可划分为早侏罗世早中期、晚期,中侏罗世早、晚期以及晚侏罗世等5个演化阶段,各阶段气候分区特征明显。其中,早侏罗世早中期(大致为埃唐日期—普林斯巴赫期)可划分为5个气候区,自北而南依次为黑龙江东部乌苏里温凉气候区、北方暖温带潮湿气候区、东南热带-亚热带潮湿气候区、西南热带-亚热带半干旱半潮湿气候区以及西藏—滇西热带海洋干旱气候区。其中,北方暖温带潮湿气候区范围最大,占据了昆仑—秦岭—大别山一线以北的广大地区。早侏罗世晚期(图阿尔期)总体升温并趋于干旱化,依然可以划分为5个气候区,但北方暖温带潮湿气候区由于南界的大幅度向北移而大为缩小,范围最广的是中部热带-亚热带半干旱-半潮湿气候区。中侏罗世早期(阿伦期—巴柔期)气温较早侏罗世晚期明显下降,北方暖温带潮湿气候区南界向南推移,基本恢复到了早侏罗世早中期的范围,东南地区为热带-亚热带半干旱-半潮湿气候。中侏罗世晚期(巴通期—卡洛维期)又复升温趋干,气候区界线再度北移,暖温带潮湿气候区范围再次大幅度缩小到燕辽及东北地区,热带-亚热带半潮湿-半干旱气候区范围扩大至整个华北与西北地区,南方则为热带-亚热带干旱气候区。晚侏罗世气温进一步升高,暖温带潮湿气候区退缩至东北一隅,除滇、藏热带海洋干旱气候区外,其他广大地区均为热带-亚热带干旱气候,且多地出现荒漠化。 相似文献
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黄土在我国西北地区广泛分布,是当地垃圾填埋场封顶覆盖层的主要材料,该材料的气体渗透特性直接影响了覆盖层对填埋气释放的控制效果。利用渗析技术和自制的气体渗透系数测量装置,模拟和测试了干湿气象条件下覆盖黄土服役含水率变化及其对气体渗透系数的影响,并建立填埋气在垃圾体和覆盖层中的一维稳态运移模型,分析了覆盖层气体渗透系数和抽气速率对填埋气释放控制效果的影响。研究结果表明：渗析技术能有效模拟覆盖黄土服役含水率的变化,压实黄土试样的气体渗透系数介于10-17～10-12 m2量级,随服役含水率的增加而降低,且对于压实度比较高的黄土降低得更加明显;覆盖层底部的填埋气压随气体渗透系数的减小而增大,通过覆盖层下部的气体扩散层负压抽气等措施,可有效减小覆盖层底部气压和填埋气的释放量。 相似文献
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Soil water conservation is essential to the sustainability of sandy farming. In this paper, long-term observation of soil water, dry soil thickness and soil chemical changes are evaluated at eight locations in sandy soil. This paper subdivides the sandy lands and deserts of China into three climate zones: arid (hyperarid and extremely arid), semiarid, and humid (subhumid and subtropical humid), with respect to the bioclimatic zone, aridity, soil water content, and soil chemical characteristics. The water movement conditions, and chemical variations in each zone are analyzed. The paper also estimates the spatial and temporal correlation function of arid soil thickness and soil moisture. Sandy soils organic matter content, CaCO3 content, soluble salts content are investigated. Afforestation and selection of tree species in different sandy areas are suggested to regulate sandy land soil moisture. Sandy land in China can be divided into the four sand stabilization regions according to the shifting sand conditions and the techniques advanced: regions I, II, III, and IV. These results have important implications for remote sensing of soil moisture and soil organic carbon, and soil moisture parameterization in climate models. 相似文献
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The study area is located in the western part of the loess plateau of China where the climate is continental semiarid and typical loess ridges and hillocks are developed. It is a very difficult terrain for mineral exploration. Samples of drilling chips, loess and red soil, well and spring water, vegetation, and soil gas were collected. The results showed that Zn, Pb, Cu, Ag, As, Mo, Sb, Hg, S, and so forth were transported into the overburden in different ways. Efficient methods for geochemical exploration in the regions overlain by loess and red soil are established. Hydrogeochemical exploration can be used on a regional scale and soil gas and partial extractions of soil can be used for follow-up studies. 相似文献
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The impact of high-intensity coal mining on water resources has drastically affected the local environment in the Yushenfu mining area, Northwest China. Many studies have ascertained that coal mining has caused reduction of the phreatic water level and vegetation death, which has deteriorated the fragile arid and semiarid ecosystems. However, at Jinjitan coal mine, it has been observed that the phreatic water level rose due to coal mining, which has been beneficial for the local ecology, especially the vegetation. In this study, the variation of the phreatic water table and its ecological effects were investigated by in-situ tests and remote sensing. The results suggest that the recovery of the permeability of the loess aquitard controls the vertical leakage of phreatic water, whereas horizontal recharge is controlled by land subsidence. An ecological impact evaluation, using the normalized difference vegetation index (NDVI), demonstrates that the vegetation is being gradually improved. Compared to a small improvement of ~9.7% in the unexploited area, a?~23.3% improvement occurred in the exploited area where low-density shrubs transformed to high-density shrubs and herbs. Emergence of phreatic water at the land surface in low-lying areas of the working faces may induce the formation of an oasis and wetland system in arid and semiarid areas. These findings could change the conventional negative impression around mining and improve ecological restoration practices.
相似文献14.
The water resource and its change of mountainous area are very important to the oasis economic system and ecosystem in the arid areas of northwest China. Accurately understanding the water transfer and circulation process among vegetation, soil, and atmosphere over different hydrological units in mountainous areas such as snow and ice, cold desert, forest and grassland is the basic scientific issue of water research in cold and arid regions, which is also the basis of water resource delicacy management and regulation. There are many research results on the hydrological function of different land covers in mountain areas, basin hydrological processes, however, there are only very limited studies on the water internal recycle at basin scale. The quantitative study on the mechanism of water internal recycle is still at the starting stage, which faces many challenges. The key project “Study on water internal recycle processes and mechanism in typical mountain areas of inland basins, Northwest China” funded by National Natural Science Foundation of China will select the Aksu River and Shule River Basin, which have better observation basis, as study area. The internal mechanism of moisture transfer and exchange process of different land cover and atmosphere, the internal mechanism of water cycle in the basin, and water transfer paths in atmosphere will be studied through enhancing runoff plot experiments on different land cover, analyzing the mechanism of water vapor transfer and exchange between different land covers in the watershed by isotope tracing on the water vapor flux of vegetation water, soil moisture and atmospheric moisture, improving the algorithms of remote sensing inversion and ground verification on land surface evapotranspiration on different land cover, and analyzing the water vapor flux from reanalysis data, and the coupling modeling of regional climate model and land surface process model. At last, the effect of different land cover in hydrological process of mountain area, and the impact of land cover on downstream oasis will be systematically analyzed. 相似文献
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Extracting desertification from Landsat TM imagery based on spectral mixture analysis and Albedo-Vegetation feature space 总被引：1，自引：0，他引：1
Land desertification has been a worldwide environmental problem. Desertification monitoring and evaluation are very important content in desertification context. Scientific and accurate evaluation of desertification can provide scientific basis for decision making in mitigating desertification. Because of the advantage of large amount of information, short cycle and broad scope of data, less restrictions on the human and material resources and so on, remote sensing has become an important technology to monitor land desertification in the past 30 years. Desertification is the most typical and serious form of desertification in China, especially in the oasis zone distributed along inland rivers or in the lower reaches of inland rivers in northwestern China. Quantitative evaluation of the current desertification remote sensing methods used is mostly obtained through the vegetation index and vegetation cover, to gain information on the extent of desertification. As the arid and semiarid sparse vegetation cover, soil and soil moisture on the most common vegetation index have a greater effect. First, based on the spectral mixture analysis model, three kinds of endmember consisting of vegetation, water and bare soil were selected. The image dimensionality was reduced by the minimum noise fraction (MNF). The pixel purity index transformation was used to narrow the range of the endmember. On the scatter plot of MNF, three kinds of endmember were selected, and relative abundance distribution of each component was obtained by using linear spectral mixture model. Second, a spectral feature space composed of vegetation component and land surface albedo retrieved from Landsat TM Imagery was constructed to evaluate desertification present condition and degree quantificationally. Last, an empirical study was carried out taking the middle reaches of Heihe River as an example. Results indicated that this method makes full use of multi-dimensional remote sensing information, reflecting the desertification land cover, water, thermal environment and its changes, with a clear biophysical significance, and the index is simple, easy to obtain, high precision, and is conducive to quantitative analysis, monitoring and desertification assessment of desertification. It was rather ideal to assess desertification on the basis of Albedo-Vegetation feature space: correct prediction proportion of testing samples reached 90.3 %. This method was beneficial to the desertification quantitative analysis and monitoring with the characteristics of simple index, easy accessibility and high accuracy. 相似文献
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黄土的本质与形成模式 总被引：11，自引：2，他引：11
根据显微结构鉴定,有机质分析,颗粒分析,CaCO3测定和野外观察、统计等资料,研究了黄土的本质和形成模式。资料表明,黄土具有土壤的各种结构,具有指示草原和森林草原土壤发生特征的CaCO3和CaSO4淀积成分,含有土壤的有机质;黄土的本质是土壤,是在相对冷干气候条件下发育的多种灰黄色狭义土壤,而且是在当时当地气候条件下处于稳定状态的发育成熟的古土壤;黄土形成模式是风尘经草原、森林草原和荒漠草原区的成壤作用形成土壤的模式。黄土高原是世界上土壤资源最深厚、最富集的地区,黄土的工程地质性质和水文地质性质在很大程度上取决于成壤作用的强弱。 相似文献
17.
指出了用水文统计法确定的“水资源总量”难以将西北干旱地区与我国东部地区水资源作出合理的比较分析.只有考虑了土壤水这一重要水资源分量才能予以改进,因为两地的土壤水在水文统计中有不同的含义.在干旱地区,土壤水主要来自灌溉水,即“水资源总量”的一部分;而在华北等地,它主要来自降水,未能统计在“水资源总量”中. 相似文献
18.
海流兔河流域植被分布与地形地貌及地下水位关系研究 总被引：1，自引：0，他引：1
干旱区植被与地形地貌及地下水的相互依存关系是揭示植被生态水文过程的关键。由于降水稀少,中国西北地区植被的生长发育与地貌和地下水的关系极为密切,从大尺度上研究地形地貌和地下水变化的生态效应问题对生态环境的保护和恢复具有重要的意义。应用遥感方法,基于地形地貌和地下水位观测数据,在流域尺度上定量地研究了中国鄂尔多斯高原海流兔河流域植被发育与地形地貌和地下水埋深的关系。结果表明：河谷、滩地、沙丘、沙地地貌的植被发育状况是依次变差的,植被在高程1 220 m左右处发育最好。地下水位埋深对植被的影响范围为1~5 m,当地下水位埋深超过5 m时,气候与土壤因素是决定植被的主要因素,地下水位的变化对植被的长生状况影响不大。 相似文献