珠江口断裂的活动性与区域稳定性分析

珠江口及邻域断裂构造有两种类型,沿岸中生代活动陆缘形成的NNE向压剪性断裂系,挽近活动较弱;珠江口新生代陆缘扩张形成的NEE向张剪性断裂系,挽近活动较强。珠江口潜在的地震危险性主要来自NEE向滨海断裂带,潜在震源区(≤6.5级)大致位于担杆列岛附近海域。珠海、深圳经济特区及邻近沿海是属于相对较稳定的地区。     

面向SDGs的OECD成员国可持续发展水平测度及时空演变研究：1995—2017年

可持续发展是当前世界各国共同追求的发展模式,《联合国2030可持续发展议程》再一次明确了可持续发展的目标,OECD成员国作为世界上经济最为发达和HDI指数最高的国家,探究其可持续发展水平的构成具有重要的理论和现实意义。以OECD成员国为研究对象,构建可持续发展评价体系,采用投影寻踪模型、变异系数、基尼系数、Pearson相关等方法,探析OECD成员国可持续发展水平的时空演变特征。结果表明：（1）1995年以来OECD成员国可持续发展水平持续提升,平均综合评价值由2.093增加到2.628,主要源于经济效率和社会发展的提升。（2）空间上呈现出可持续发展水平北欧＞西欧、中欧、东亚、北美、大洋洲＞西亚、东欧＞拉丁美洲的格局,基尼系数由0.089降低为0.065,区域差异不断缩小。（3）随着可持续发展水平提升,在可持续发展水平高值区主导要素逐步由单要素主导转变为多要素共同主导,而在可持续发展水平低值区由生态环境和资源安全主导逐步转为经济效率主导。     

Spatial and temporal characteristics of droughts in Luanhe River basin,China

Theoretical and Applied Climatology - The spatial and temporal characteristics of drought are investigated for Luanhe River basin, using monthly precipitation data from 26 stations covering the...     

Monotone multiscale finite volume method

The MultiScale Finite Volume (MSFV) method is known to produce non-monotone solutions. The causes of the non-monotone solutions are identified and connected to the local flux across the boundaries of primal coarse cells induced by the basis functions. We propose a monotone MSFV (m-MSFV) method based on a local stencil-fix that guarantees monotonicity of the coarse-scale operator, and thus, the resulting approximate fine-scale solution. Detection of non-physical transmissibility coefficients that lead to non-monotone solutions is achieved using local information only and is performed algebraically. For these ‘critical’ primal coarse-grid interfaces, a monotone local flux approximation, specifically, a Two-Point Flux Approximation (TPFA), is employed. Alternatively, a local linear boundary condition can be used for the dual basis functions to reduce the degree of non-monotonicity. The local nature of the two strategies allows for ensuring monotonicity in local sub-regions, where the non-physical transmissibility occurs. For practical applications, an adaptive approach based on normalized positive off-diagonal coarse-scale transmissibility coefficients is developed. Based on the histogram of these normalized coefficients, one can remove the large peaks by applying the proposed modifications only for a small fraction of the primal coarse grids. Though the m-MSFV approach can guarantee monotonicity of the solutions to any desired level, numerical results illustrate that employing the m-MSFV modifications only for a small fraction of the domain can significantly reduce the non-monotonicity of the conservative MSFV solutions.     

场地土壤污染物含量三维刻画的研究进展

污染场地精准修复与再开发利用是改善人居环境、建设美丽中国所面临的重要课题。场地土壤污染物含量三维刻画是精准修复与再开发利用的基础。然而,场地环境是一个耦合地上地下多要素的复杂三维系统,使得基于离散稀疏土壤钻井样点和空间统计推断模型的场地土壤污染物含量刻画结果存在着较大的不确定性。本文梳理了场地土壤污染物含量三维精细刻画的目的和钻井布设方式、常用的三维刻画模型和相关案例,分析了土壤钻井数据的“稀疏偏性”特征对刻画结果的影响,总结了“非平稳浓度场”条件下三维土壤污染物含量插值模型的研究现状和存在问题。在此基础上,从多情景、非平稳、非线性、多源数据融合、多类模型耦合和复合污染刻画6个方面,展望了场地地下“黑箱”环境土壤污染物含量精细刻画的研究趋势。     

基于大气电场的雷电监测预警方法

利用大气电场强度数据设计了一种雷电监测预警方法,并对江西省南昌县2020年8月的一次雷电过程进行预测。首先对大气电场仪采集的电场数据进行去噪处理和缺失填补,然后利用经验模态分解法分解大气电场数据,得到大气电场数据的幅值和频率的分布特征,运用多元回归模型构建雷电预警模型,预测未来一段时间内的大气电场强度值。参考大气电场强度等级划分表,开展雷电监测预警。结果表明,运用模型预测的大气电场强度结果与实况之间的可决系数均在0.9以上,即大气电场强度预测结果与实况较为接近,该监测预警方法具有一定的可行性。     

山东渤海滨海湿地演变特征及其与人类活动相关性研究

滨海湿地是受人类活动影响最显著的地区之一,研究以山东渤海滨海地区为对象,针对1990、2000、2010、2019年遥感影像数据,运用人类活动强度模型和皮尔逊相关系数等方法,探究人类活动影响下滨海湿地演变规律,揭示人类活动与土地利用类型的一般关系,得出以下结论：（1）1990—2019年研究区湿地面积总体增加,人工湿地显著增加,自然湿地显著减少,大面积自然湿地向人工湿地转化,其中黄河三角洲是研究区内自然湿地保留最完好的地区;（2）1990—2019年人类活动强度不断增加,平均值由1990年的8.48上升至2019年的17.07,增幅为101.30%;在不同人类活动强度区,湿地对其起到的主导作用与强弱程度成反比;（3）研究期内,伴随盐田及建设用地面积的不断增加和自然湿地向其他地类的转化,人类活动中-高强度区湿地面积总量较少但不断增加,低强度区湿地面积不断减少但总量较多;（4）从各城市相关性检验结果来看,不同城市人类活动影响因素与湿地面积的相关性存在一定差异,总体上人类活动影响因素与人工湿地呈显著相关,与自然湿地呈显著负相关或不相关。研究可为山东渤海滨海地区湿地保护及应对人为过度开发湿地的行为提供科学依据和重要借鉴。     

Formation,mechanism and significance of alluvial-dammed lakes in Golmud River catchment,north-eastern Qinghai-Tibetan Plateau

This study investigated a series of dammed lakes and downstream-adjacent alluvial fans in the upstream to middle reaches of the Golmud River in the eastern Kunlun Mountain, on the north-eastern Qinghai-Tibetan Plateau (QTP). An optically stimulated luminescence (OSL) chronology shows the sediments of five dammed lakes developed from c. 45–40, 30–25, 18–14, and 12–8 ka, corresponding to MIS 3b, late MIS 3a, Last Deglaciation, and early Holocene, respectively. The remote sensing data show these dammed lakes have a total area of 109.4 km², with the lake volume of more than 4.0 km³. Symmetric alluvial fans from north–south tributary valleys produced OSL ages of c. 61–52, 42–31, 26–20, and 16–10 ka, corresponding to glaciation periods: the MIS 3c and MIS 3a, MIS 2, and the Last Deglaciation. This suggests that glacial activity is responsible for the alluvial fan development, where dammed rivers occurred first, but lake formation did not take place synchronously until later periods of strong hydrologic activity, resulting from northward intrusions of the Indian summer monsoon (ISM) or glacier melt. Thus, the blocking pattern is that river valleys were dammed during periods of glacial activity and lakes formed during wet periods. The lake formation and subsequent drainage may have resulted in: (i) impeded headwater incision and strengthening of downstream dissection; (ii) enriched the halite and potash in the distal Qarhan Salt Lake through hydrologic and hydrochemical processes of abundant water input, the salt lake expansion, salt redissolution from playa and final resedimentation during later dry periods. The alluvial-dammed lake pattern in the mountain-basin systems of eastern Kunlun Mountain offers a model for assessing the linkages between monsoon dynamics, geomorphic processes and distal salt lake evolutions in other arid regions.     

Have China’s drylands become wetting in the past 50 years?

Recently, whether drylands of Northwest China (NW) have become wetting has been attracting surging attentions. By comparing the Standard Precipitation Evapotranspiration Indices (SPEI) derived from two different potential evapotranspiration estimates, i.e., the Thornthwaite algorithm (SPEI_th) and the Penman-Monteith equation (SPEI_pm), we try to resolve the controversy. The analysis indicated that air temperature has been warming significantly at a rate of 0.4°C decade^?1 in the last five decades and the more arid areas are more prone to becoming warmer. Annual precipitation of the entire study area increased insignificantly by 3.6 mm decade^?1 from 1970 to 2019 but NW presented significantly increasing trends. Further, the SPEI_th and SPEI_pm demonstrated similar wetting-drying-wetting trends (three phases) in China’s drylands during 1970-2019. The common periodical signals in the middle phase were identified both by SPEI_th and SPEI_pm wavelet analysis. Analysis with different temporal intervals can lead to divergent or even opposite results. The attribution analysis revealed that precipitation is the main climatic factor driving the drought trend transition. This study hints that the wetting trend’s direction and magnitude hinge on the targeted temporal periods and regions.