Potential wind erosion rate response to climate and land‐use changes in the watershed of the Ningxia–Inner Mongolia reach of the Yellow River,China, 1986–2013

Climate and land‐use changes could strongly affect wind erosion and in turn cause a series of environmental problems. Thus, the objective of this study was to assess potential wind erosion rate (PWER) response to climate and land‐use changes in the watershed of the Ningxia–Inner Mongolia Reach of the Yellow River (NIMRYR), China. The watershed of NIMRYR suffers from serious wind erosion hazards, and over recent decades, wind erosion intensity and distribution has changed, following climate and land‐use changes. To understand these processes in the NIMRYR watershed, the Integrated Wind Erosion Modelling System (IWEMS) and the Revised Wind Erosion Equation (RWEQ) were used to calculate the PWER under different climate conditions and land‐use scenarios, and to assess the influences of climate and land‐use changes on the PWER. The results show the PWER in the whole watershed had a significant declining trend from 1986 to 2013. The results of the relationship among PWER, climate change, and land‐use changes showed that climate change was the dominant control on the PWER change in this watershed. Compared to the period 1986–1995, the average PWER decreased 23.32% and 64.98% as a result of climate change in the periods 1996–2005 and 2006–2013, respectively. In contrast with climate change, the effects of land‐use changes on the average PWER were much lower, and represented a change in PWER of less than 3.3% across the whole watershed. The study method we used could provide some valuable reference for wind erosion modelling, and the research results should help climate and land‐use researchers to develop strategies to reduce wind erosion. Copyright © 2017 John Wiley & Sons, Ltd.     

三维复杂地壳结构非线性走时反演

中国大陆中西部乃至全球造山带普遍具有复杂地壳结构.随着矿产资源勘探和深部探测研究的深入,探测造山带及盆山耦合区下方地壳精细结构正逐渐成为当前面临的巨大挑战.人工源深地震测深方法正越来越清晰地揭示出不同构造域地壳速度结构的基本特征,然而传统的层状结构模型参数化方法难以准确描述复杂地质模型,通常情况下多忽略速度结构的精细间断面且采用层边界平滑处理,难以满足地壳精细结构成像的发展要求.针对上述困难,本文采用最近发展的块状结构建模方案构建三维复杂地壳模型,基于逐段迭代射线追踪正演走时计算方法,推导了走时对三角形界面深度以及网格速度的偏导数,开展了非线性共轭梯度走时反演方法研究.发展了利用直达波和反射波等多震相走时数据对界面深度和网格速度的多参数联合反演方法,并引人不同种类震相数据的权系数和不同类型参数偏导数归一化的方法.数值算例表明,基于块状结构的非线性共轭梯度走时反演方法适用于复杂地壳结构模型,在利用人工源走时数据反演复杂地壳精细结构领域具有良好的应用前景.     

水平层状非均质TI地层中仪器偏心情况下三维感应测井响应高效数值模拟与响应特征分析

本文针对中国石油集团测井有限公司(CPL)三维阵列感应测井仪器(Three Dimensional Induction Tool,TDIT)的真实结构与参数,利用2.5维数值模式匹配技术研究建立水平层状非均质TI地层中仪器偏心情况下三维感应测井响应的高效数值模拟算法.首先,利用2.5维数值模式匹配技术给出水平层状非均质TI模型中偏心磁流源并矢Green函数的半解析解.在此基础上,结合三维阵列感应测井仪器参数以及测量过程中出现的仪器偏心与旋转等实际情况,通过叠加原理推导出该仪器响应的有效计算公式.最后,通过数值模拟结果分析考察仪器偏心、仪器自旋角等参数对测井响应的影响以及变化特征,为多分量感应资料处理与解释提供理论基础.     

大震下村镇建筑砌体结构的抗震性能数值分析

为探讨村镇建筑低层砌体结构在大震下的动力响应及损伤分布情况,基于农居结构性能实地调查与检测,在有限元软件ABAQUS中建立了不同抗震构造措施的砌体结构有限元模型,并进行结构动力特性及大震下弹塑性时程的分析,对比它们的自振特性参数、位移响应参数及损伤破坏形态。分析表明,低层砌体结构合理设置构造柱后结构自振周期略有减小,但振型不变;在弹性变形阶段构造柱能有效约束结构的动力位移响应,进入塑性变形后构造柱可提高砌体结构的耗能能力,但值得注意的是,结构刚度退化后构造柱会加剧纵横向抗侧刚度的不均衡性;低层砌体结构合理设置圈梁构造柱可有效抑制承重横墙的裂缝发展及楼屋盖发生支座失效破坏,且可以明显削弱结构的扭转效应。     

四川2015速度模型在九寨沟M_S7.0地震震源深度测定中的应用

利用四川2015模型,选择Msdp嵌入的几种常用定位方法对九寨沟M_S7.0地震进行重新定位,比较震源深度结果,并用PTD方法验证合适的震源深度,从而得到较为可靠的震源深度。本文最终判定九寨沟M_S7.0地震震源深度为12±2km。     

2017年九寨沟地震前重力场异常特征提取

2017年8月8日九寨沟发生7.0级地震,此次地震发生在塔藏断裂、岷江断裂和虎牙断裂附近,震源机制为走滑型。重力场静态异常和动态异常变化可为研究深地壳结构性质提供重要的物理场信息。本文利用WGM计算的布格重力异常数据及实测流动重力数据进行小波多尺度分解,分离得到不同深度场源特征的地壳介质横向不均匀性。结果表明,WGM布格重力异常数据和实测重力数据的小波多尺度结果较为一致,通过对比分析发现,九寨沟地震发生在区域重力场的四象限分布中心位置,不同时空尺度的重力场变化对于深入认识潜在地震危险性趋势具有一定的科学意义。     

山东省菏泽郓城地区地热资源赋存条件评价

山东省菏泽郓城地区地热资源丰富,主要赋存于奥陶系和寒武系灰岩中,为估算评价该区的地热资源,在收集资料、野外勘查的基础上,施工1眼地热井,结合收集该区30余眼地热井资料,基本查清了郓城地区的地热赋存条件,确定奥陶系和寒武系热储为本次研究对象,对郓城地区地热流体质量进行了评价,地热资源量进行了计算。评价结果,为持续做好郓城地区地热资源开发利用工作,带动当地经济发展,构建能源节约型社会提供了数据支持。     

THE APPLICATION OF MINIATURE UNMANNED AERIAL VEHICLE IN 25 NOVEMBER 2016 ARKETAO MW6.6 EARTHQUAKE

In order to complete the field investigation to the 25 November 2016 Arketao M_W6.6 earthquake, ultra-low altitude remote-sensing data were obtained from miniature unmanned aerial vehicle. The surface rupture surveying has important significance for earthquake research. This paper selects the macro-epicenter of Arketao as the study area. The pictures were obtained with DJI Phantom 3 professional input into the software, the Digital Elevation Model (DEM), Digital Orthophoto Map (DOM) were acquired based on photogrammetry method using the overlapped optical remote-sensing images of UAV. Using these data, we can identify surface ruptures that have vertical dislocation. We selected six feature points and drew the elevation profile. In the elevation profile map, we chose smooth part of the surface rupture sides and obtained the trend line. A stable point in the surface rupture was selected and the abscissa of the point was taken into the equation of two straight lines. Then subtracting the results of the two equations, we can get the vertical dislocation of the surface rupture. On this basis, we chose six feature points and determined their vertical dislocation, which are between 4.4cm and 10.4cm. What's more, taking Bulungkou Xiang in Xinjiang Uygur Autonomous Region for example, we speculated some surface ruptures that have vertical dislocation. It can provide a new method for identifying surface rupture in the field. In addition, we get DEM data of the Bulunkou area where ambient conditions are very poor, by using miniature unmanned aerial vehicle and taking 255 photos. Putting those photos into the EasyUAV software, we got the area digital elevation of 2cm resolution. Comparing these data with RTK data, we summarized some practical problems and solutions in the practical operation and evaluated the accuracy of miniature unmanned aerial vehicle data. The Pearson Correlation Coefficient is 0.996 6. In terms of absolute elevation, the average result of UAV and RTK differs by 156.96m. In terms of relative elevation, the average result of UAV and RTK differs by 9.74m. Compared with the previous test of Pishan County, there is a notable divergence in the results. It shows that the data accuracy will be affected to some extent in the cold weather in high elevations. The specific impact needs further exploration.     

高强度地震下建筑施工场点危险性建模分析

在高强度地震环境下,建筑施工场点易发生危险,传统方法运用AHP算法对建筑施工场点的危险性进行分析,但未考虑抗震约束,存在分析效果差的弊端。因此,提出一种高强度地震下建筑施工场点危险性建模分析方法。首先采用TOPSIS方法得到地震风险评估指标,构建风险评估指标的物元分析模型,基于AHP-熵权法的组合赋权获取地震风险评估指标的综合权重。然后通过贝叶斯网络来推导高强度地震下建筑施工场点危险性参数,运用地震等级的划分标准和推算方法,依据建筑施工场点危险性评估准则和接受原则APLARP,利用物元分析模型中不同危险节点的致因关系和综合权重构建施工场点风险评估模型,完成对高强度地震下建筑施工场点危险性的建模分析。实验结果表明,所设计模型可准确分析高强度地震下建筑施工场点的危险性,能够确保整体施工的安全性,具有重要的应用价值。     

Variation in soil saturated hydraulic conductivity along the hillslope of collapsing granite gullies

Saturated hydraulic conductivity (K_s) affects the soil hydrological process and is influenced by many factors that exhibit strong spatial variations. To accurately measure K_s and its scale, spatial variability and relationship with collapsing gullies, we analysed four double-ring infiltrometer diameters in three soil layers during in situ experiments designed to measure K_s in two typical collapsing gullies (three slope sites) in Tongcheng County of China. The results showed that K_s increased with increasing inner ring diameter, but no significant difference existed between inner diameters of 30 and 40 cm. The K_s in red soil layers was higher than that in sandy soil layers, the transition layers had the lowest values. K_s also varied with slope position, gradually decreasing with distance from the gully head. The suggestion is that the spatial variation in K_s is affected not only by the intrinsic soil properties but also by the interaction with the collapsing gully.