砒砂岩区地貌形态三维分形特征量化及空间变异

针对现有地貌形态三维分形模型结构存在的不足,构建一个新的地貌形态三维分形维数测算模型。基于该模型对砒砂岩区274个小流域的地貌形态三维分形维数进行计算并分析其空间变异规律。研究表明：① 基于该模型计算的分形维数能更准确地反映地貌形态复杂度信息;② 砒砂岩区小流域地貌形态三维分形维数介于1.683 6~1.948 6之间;③ 地貌形态三维分形维数整体上覆土砒砂岩区（均值为1.765 9）<裸露砒砂岩强度侵蚀区（均值为1.785 4）和剧烈侵蚀区（均值为1.774 8）<覆沙砒砂岩区（均值为1.796 6）。由于地表覆盖物、砒砂岩裸露程度和土壤侵蚀机理的差异而形成的不同地貌特征是该区地貌形态分形特征空间变异的主要原因。     

科尔沁沙地固定沙丘土壤水体积分数变化

利用2006-2009年5-9月科尔沁沙地固定沙丘0~150 cm土壤水体积分数监测数据及降水资料,采用偏度、峰度检验法检验了固定沙丘不同月及不同土层土壤水体积分数的正态性,并得到了其正态分布相关参数的估计值及其置信区间;同时,对不同土层、不同月及不同年间的土壤水体积分数变化和差异进行了分析。结果表明:(1)固定沙丘同一月的土壤水体积分数以显著性水平α=0.1通过正态分布的假设检验;固定沙丘土壤水体积分数的平均值范围1.82%~4.95%,主要集中在2%~4%;(2)受降水影响,固定沙丘7月土壤水体积分数较高,且与其他月的差异显著;7月土壤水体积分数均值和方差的点估计及置信水平为0.95的置信区间、统计特征均与其他月的有较大差异;(3)固定沙丘0~10 cm土壤水体积分数较低,且与其他土层有显著差异;而10~30 cm土壤水体积分数较高;(4)2008年土壤水体积分数较低,而2009年土壤水体积分数较高;除2007年与2008年土壤水体积分数没有显著差异外,其余年份间的土壤水体积分数均有显著差异。     

2000-2012年陕甘宁黄土高原区地表蒸散时空分布及影响因素

分析陕甘宁黄土高原区地表蒸散变化特征及其影响因素,可以为区域水资源规划、生态环境改善提供依据。本文利用MOD16蒸散数据,统计分析了陕甘宁黄土高原区2000-2012年地表实际蒸散量的时空变化特征,并结合国家气象站点观测数据和基于像元的相关分析法探讨了其影响因素。结果表明:(1) 2000-2002年蒸散量迅速上升,在2003年达到最高值378.6 mm, 2003-2006年蒸散量呈下降趋势,2006年之后蒸散量呈现缓慢上升趋势。(2) 近13年来,陕甘宁黄土高原区多年平均蒸散量具有明显的空间差异,蒸散量自西北至东南递增,最南部的六盘山、子午岭、黄龙山地是3个主要的高值区;年蒸散量以夏季最多,其次是春季,秋季和冬季最少,且季节蒸散的分布与年蒸散的空间分布格局基本一致。(3) 陕甘宁黄土高原区蒸散量草地和耕地的贡献率最高,密灌丛、疏灌丛次之,常绿针叶林、森林草原贡献率则较小。(4) 陕甘宁黄土高原区动力因素对地表蒸散量影响以正相关为主,风速对该区影响较大;热力因素对地表蒸散量影响以负相关为主,其中气温与蒸散在空间上呈负相关的区域较大,日照时数与蒸散在空间上的负相关区域的面积次之;水分条件(降水量、相对湿度)对蒸散的影响也以正相关为主。     

Variation characteristics of evaporation in the Gulang River Basin during 1959-2013

Based on monthly evaporation of two meteorological stations in the Gulang River Basin of China, the inter-annual variation of evaporation during 1959-2013 were analyzed using Mann-Kendall and wavelet analysis. The results demonstrated that the annual evaporation show a fluctuating increase over the past 50 years approximately, with an average increase rate of 4.26 mm per decade. The overall trend was decrease-increase-decrease. According to the cumulative anomaly curve,the turning point of the annual evaporation occurred in 1979, in which the evaporation increased in the early stage and decreased in the later stage. Meanwhile, the seasonal variation of the evaporation shows that it decreased in Spring and Autumn, and increased in Summer and Winter, especially obvious for the later. The evaporation abruptly changed in Spring and Summer in 2008 and in Winter in 1994. In addition, all evaporation increased after the changes. However,the evaporation in Autumn abruptly changed in 1986 and 1999, which show a trend of increase-decrease-increase.Wavelet analysis shows that evaporation in Summer and wet season would decrease in the next few years, and in the other seasons would increase. Based on the aforementioned analysis, it can be concluded that increased evaporation is mainly induced by increase of evaporation in dry season, especially in Winter, and this trend to be continued in the future for the Gulang River Basin.     

Population,urbanization and economic scenarios over the Belt and Road region under the Shared Socioeconomic Pathways

The countries throughout the Belt and Road region account for more than 60% of the world's population and half of the global economy. Future changes in this area will have significant influences on the global economic growth, industrial structure and resource allocation. In this study, the proportion of the urban population to the total population and the gross domestic product were used to represent the levels of urbanization and economic development, respectively. The population, urbanization and economic levels of the Belt and Road countries for 2020–2050 were projected under the framework of the IPCC's shared socioeconomic pathways(SSPs), and the following conclusions are drawn.(1) The population, urbanization and economic levels in the Belt and Road region will likely increase under all five pathways. The population will increase by 2%–8%/10 a during 2020–2050 and reach 5.0–6.0 billion in 2050. Meanwhile, the urbanization rate will increase by 1.4%–7.5%/10 a and reach 49%–75%. The GDP will increase by 17%–34%/10 a and reach 134–243 trillion USD.(2) Large differences will appear under different scenarios. The SSP1 and SSP5 pathways demonstrate relatively high urbanization and economic levels, but the population size is comparatively smaller; SSP3 shows the opposite trend. Meanwhile, the economy develops slowly under SSP4, but it has a relatively high urbanization level, while SSP2 exhibits an intermediate trend.(3) In 2050, the population will increase relative to 2016 in most countries, and population size in the fastest growing country in Central Asia and the Middle East countries will be more than double. Urbanization will develop rapidly in South Asia, West Asia and Central Asia, and will increase by more than 150% in the fastest growing countries. The economy will grow fastest in South Asia, Southeast Asia and West Asia, and increase by more than 10 times in some counties with rapid economic development.     

Effects of land use and cultivation time on soil organic and inorganic carbon storage in deep soils

The vertical distribution and exchange mechanisms of soil organic and inorganic carbon(SOC, SIC) play an important role in assessing carbon(C) cycling and budgets. However, the impact of land use through time for deep soil C(below 100 cm) is not well known. To investigate deep C storage under different land uses and evaluate how it changes with time, we collected soil samples to a depth of 500 cm in a soil profile in the Gutun watershed on the Chinese Loess Plateau(CLP); and determined SOC, SIC, and bulk density. The magnitude of SOC stocks in the 0–500 cm depth range fell into the following ranking: shrubland(17.2 kg m~(-2)) grassland(16.3 kg m~(-2)) forestland(15.2 kg m~(-2)) cropland(14.1 kg m~(-2)) gully land(6.4 kg m~(-2)). The ranking for SIC stocks were: grassland(104.1 kg m~(-2)) forestland(96.2 kg m~(-2)) shrubland(90.6 kg m~(-2)) cropland(82.4 kg m~(-2)) gully land(50.3 kg m~(-2)). Respective SOC and SIC stocks were at least 1.6-and 2.1-fold higher within the 100–500 cm depth range, as compared to the 0–100 cm depth range. Overall SOC and SIC stocks decreased significantly from the 5 th to the 15 th year of cultivation in croplands, and generally increased up to the 70 th year. Both SOC and SIC stocks showed a turning point at 15 years cultivation, which should be considered when evaluating soil C sequestration. Estimates of C stocks greatly depends on soil sampling depth, and understanding the influences of land use and time will improve soil productivity and conservation in regions with deep soils.     

Simulating cross-sectional geometry of the main channel in response to changes in water and sediment in Lower Yellow River

Journal of Geographical Sciences - To understand the non-equilibrium morphological adjustment of a river in response to environmental changes, it is essential to (i) accurately identify how past...     

“四层一体”在地理研学资源开发中的运用——以哈尼梯田地理研学资源开发为例

自2016年教育部等十一部门印发《关于推进中小学生研学旅行的意见》以来,社会各界对于研学旅行的研究迅速增加。因地理学研究“人地关系地域系统”这一核心问题,无疑成为研学旅行研究和实践的重要阵地。但如何开发地理研学旅行资源,尤其是如何有机结合人文地理与自然地理研学要素成为困扰很多研学导师的难题。本文尝试使用“四层一体”分析方法,从自然地理要素、生计、制度、文化四个层面出发,探讨如何从地理学科视角挖掘和利用研学资源,发现各个地理研学要素之间的相互作用关系,增强其逻辑性。     

高中地理优质课中的师生对话研究--以“大规模的海水运动”为例

本研究采用"同课异构"的研究思路,从"2015年全国地理教学研究会优质课比赛"获奖的视频课例中选取四节"大规模的海水运动"课作为样本,对四节高中地理优质课中的师生对话进行定性和定量相结合的比较研究。得出研究结论:四节课中师生对话频繁,课堂氛围活跃,但师生对话在认知水平、对话结构、师生话语权等方面存在巨大差异。这些差异将对地理核心素养的落实产生不同影响。