典型地貌景观指数的多尺度效应分析——以山西省运城市为例

景观指数作为定量描述景观特征的指数,具有明显的尺度效应.进行景观指数的尺度效应研究,对进一步理解格局与尺度之间的关系具有重要意义.本文以TM影像为基础,选择山西省运城市平原、丘陵、山地及综合地貌4种不同地貌类型,对7个常用景观指数进行了多尺度效应分析.结果表明:不同地形上斑块密度(PD)、景观形状指数(LSI)、结合度(COHESION)3个指数有明显的粒度效应,随粒度的增加呈现逐渐减少的变化趋势;最大斑块指数(LPI)、周长面积比分维数(PAFRAC)、景观聚集度(CONTAG)和Shannon多样性指数(SHDI)4个指数随粒度的增加几乎不发生变化.不同地貌的景观指数随幅度的变化规律比较复杂,景观形状指数(LSI)随幅度的增加呈现逐渐增加的趋势,其余6个指数在较小幅度范围内变化比较复杂,但随着幅度的增大有逐渐趋于平稳的趋势.针对研究区不同地貌类型,其景观指数在不同粒度和幅度下有较大区别,可以根据景观指数值的大小来区分地貌的复杂程度.     

电性参数在煤层气测井中的应用

在煤层气测井中,利用自然电位和双侧向电阻率可以定性判断含气层位。利用电阻率参数可推算煤层的孔隙度和含气饱和度,结合密度对煤层气可以进行定量计算。．     

Evolution of the freeze-thaw cycles in the source region of the Yellow River under the influence of climate change and its hydrological effects

As an important water source and ecological barrier in the Yellow River Basin, the source region of the Yellow River (above the Huangheyan Hydrologic Station) presents a remarkable permafrost degradation trend due to climate change. Therefore, scientific understanding the effects of permafrost degradation on runoff variations is of great significance for the water resource and ecological protection in the Yellow River Basin. In this paper, we studied the mechanism and extent of the effect of degrading permafrost on surface flow in the source region of the Yellow River based on the monitoring data of temperature and moisture content of permafrost in 2013–2019 and the runoff data in 1960–2019. The following results have been found. From 2013 to 2019, the geotemperature of the monitoring sections at depths of 0–2.4 m increased by 0.16°C/a on average. With an increase in the thawing depth of the permafrost, the underground water storage space also increased, and the depth of water level above the frozen layer at the monitoring points decreased from above 1.2 m to 1.2–2 m. 64.7% of the average multiyear groundwater was recharged by runoff, in which meltwater from the permafrost accounted for 10.3%. Compared to 1960-1965, the runoff depth in the surface thawing period (from May to October) and the freezing period (from November to April) decreased by 1.5 mm and 1.2 mm, respectively during 1992–1997, accounting for 4.2% and 3.4% of the average annual runoff depth, respectively. Most specifically, the decrease in the runoff depth was primarily reflected in the decreased runoff from August to December. The permafrost degradation affects the runoff within a year by changing the runoff generation, concentration characteristics and the melt water quantity from permafrost, decreasing the runoff at the later stage of the permafrost thawing. However, the permafrost degradation has limited impacts on annual runoff and does not dominate the runoff changes in the source region of the Yellow River in the longterm.     

转型期上海社会空间分异研究

采用2000年第五次全国人口普查数据库中居民委员会尺度的数据,对转型期上海城市空间重构与分异展开研究。存在6类社会区：计划经济时代建设的工人居住区、外来人口集中居住区、白领集中居住区、农民居住区、新建普通住宅居住区、离退休人员集中居住区。通过计算分异指数,发现当前上海存在严重的住房分异;但并不存在明显的以社会经济属性为基础的社会空间分异。造成这一现象的原因在于计划经济时代的历史以及仍然存在的大型企事业单位对住房的影响。中国城市目前的社会空间分异在程度上与西方城市还有根本的差异。     

Late Pliocene to late Pleistocene environments preserved at the Palisades Site, central Yukon River, Alaska

The Palisades Site is an extensive silt-loam bluff complex on the central Yukon River preserving a nearly continuous record of the last 2 myr. Volcanic ash deposits present include the Old Crow (OCt; 140,000 yr), Sheep Creek (SCt; 190,000 yr), PA (2.02 myr), EC (ca. 2 myr), and Mining Camp (ca. 2 myr) tephras. Two new tephras, PAL and PAU, are geochemically similar to the PA and EC tephras and appear to be comagmatic. The PA tephra occurs in ice-wedge casts and solifluction deposits, marking the oldest occurrence of permafrost in central Alaska. Three buried forest horizons are present in association with dated tephras. The uppermost forest bed occurs immediately above the OCt; the middle forest horizon occurs below the SCt. The lowest forest bed occurs between the EC and the PA tephras, and correlates with the Dawson Cut Forest Bed. Plant taxa in all three peats are common elements of moist taiga forest found in lowlands of central Alaska today. Large mammal fossils are all from common late Pleistocene taxa. Those recovered in situ came from a single horizon radiocarbon dated to ca. 27,000 ¹⁴C yr B.P. The incongruous small mammal assemblage in that horizon reflects a diverse landscape with both wet and mesic environments.     

珞珈一号夜间灯光影像在建设用地提取中的应用:以武汉市为例

城市建设用地能够反映城市建设发展在地域空间上的分布形态,是规划主管部门监测城市建设和扩张的关键指标.2018-06-02发射的珞珈一号卫星可提供130 m分辨率的夜间灯光数据,在城市建设用地的提取方面具有较大潜力.首先整合珞珈一号夜间灯光影像与Landsat 8多光谱影像以及网络地图兴趣点数据;然后分别采用人类居住合成...     

冬季白令海海冰范围变化及其对大气响应机制研究

白令海是冬季北极海冰变化最明显的区域之一,该区域海冰的季节和长期变化与局地的气候、水文环境和生态系统密切相关,并会影响我国的天气气候过程。为了识别该区冬季海冰的长期变化,基于Hadley中心数据,采用滑动t检验和线性回归分析方法对白令海1960–2020年海冰范围的变化趋势及其空间差异进行分析,并分析了海冰变化对大气环流等大气强迫的影响。结果表明：白令海冬季海冰范围在1960–2020年显著减小,20世纪70年代和2000年前后白令海海冰范围存在显著的均值突变。其过程中伴随着阿留申低压中心低压加强、核心位置向白令海西部偏移以及对应风场分布的变化,这个过程存在一个近20 a周期的振荡。同时,太平洋年代际震荡的相位变化可以通过改变海平面气压来调节经向风,改变进入白令海的热平流,进而影响白令海冬季海冰范围。因此,阿留申低压系统和北太平洋年代际振荡对冬季白令海海冰的变化起到重要的调节作用。     

Numerical simulations of the influence of the seasonal snow cover on the occurrence of permafrost at high latitudes

It has repeatedly been reported that snow cover is a dominating factor in determining the presence or absence of permafrost in the discontinuous and sporadic permafrost regions. The temperature at the snow-soil interface by the end of winter, known as the bottom temperature of winter snow (BTS) method, has been used to detect the existence of permafrost in European alpine regions when the maximum snow depth is about 1.0 m or greater. A critical snow thickness of about 50 cm or greater can prevent the development of permafrost in eastern Hudson Bay, Canada. The objective of this study is to investigate the impact of snow cover on the presence or absence of permafrost in cold regions through numerical simulations. A one-dimensional heat transfer model with phase change and a snow cover regime is used to simulate energy exchange between deep soils and the atmosphere. The model has been validated against the in situ data in the Arctic. The simulation results indicate that both snow depth and the onset date of snow cover establishment are important parameters in relation to the presence or absence of permafrost. Early establishment of snow cover can make permafrost disappear, even with a relatively thin snow cover. Permafrost may survive when snow cover starts after the middle of December even with a snow thickness >1.0 m. This effect of snow cover on the ground thermal regime can be explained with reference to the pattern of seasonal temperature variation. Early establishment of snow cover enhances the insulating impact over the entire cold season, thus warming and eventually thawing the permafrost. The insulating effect is substantially reduced when snow cover starts relatively late and snowmelt in the spring creates a huge heat sink, resulting in a favorable combination for permafrost existence.     

地质灾害防治与岩土工程研究与实践

2000年以来,西部地区的交通、水利水电等基础设施建设取得了令世人瞩目的成就。依托大规模基础设施建设工程,作者及同事们经过十余年的努力,在大型复杂滑坡与高边坡病害防治方面,以及工程冻土、黄土和隧道地质问题等进行了系统的科学研究和工程实践,本文简要介绍近年来所取得的主要成果和新发展,以期今后在研究类似问题中借鉴。     

Estimating spatial variations of total evaporation using multispectral sensors within the uMngeni catchment,South Africa

Total evaporation is of importance in assessing and managing long-term water use, especially in water-limited environments. Therefore, there is need to account for water utilisation by different land uses for well-informed water resources management and future planning. This study investigated the feasibility of using multispectral Landsat 8 and moderate resolution imaging spectroradiometer (MODIS) remote sensing data to estimate total evaporation within the uMngeni catchment in South Africa, using surface energy balance system. The results indicated that Landsat 8 at 30 m resolution has a better spatial representation of total evaporation, when compared to the 1000 m MODIS. Specifically, Landsat 8 yielded significantly different mean total evaporation estimates for all land cover types (one-way ANOVA; F_4.964?=?87.011, p < 0.05), whereas MODIS failed to differentiate (one-way ANOVA; F_2.853?=?0.125, p = 0.998) mean total evaporation estimates for the different land cover types across the catchment. The findings of this study underscore the utility of the Landsat 8 spatial resolution and land cover characteristics in deriving accurate and reliable spatial variations of total evaporation at a catchment scale.