Predictive uncertainty of peak outflow relations for landslides dam breach

Risk assessment development considering the failure of landslide dams often requires the estimation of peak outflow through the breach. The empirical equations based on data from case studies tend to be the first direct approach. This paper conducted an uncertainty analysis when these empirical relations were utilized to predict the peak outflow of a breached landslide dam. The results suggest that the relations derived from manmade dams or embankments typically overestimate the peak outflow about 1/5 to 3/4 of an order of magnitude; and the relations derived from the database of landslide dams have much smaller mean prediction errors and also exhibit broad uncertainty bands. Application of the uncertainly analysis was illustrated by the Tangjiashan landslide dammed lake, formed during 2008 Wenchuan earthquake. In addition, the predicted results from Eq. 1 deduced herein were considered to be the reliable estimate of peak outflow through the breach of landslide dam.     

安徽淮北平原冬小麦气候适宜度分析及作物年景评估

选取安徽省淮北平原37个气象站1960-2016年逐日气象资料,构建气温、降水、日照及气候适宜度模型,分析气候变暖背景下冬小麦气候适宜度时空演变特征,揭示冬小麦生育期气候风险,评判农业气候年景。结果表明：淮北平原冬小麦不同生育期对气候因子适宜程度不同,单要素各生育期适宜度均为灌浆-乳熟期较高,返青-拔节期较低,其中降水适宜度分蘖期最低;全生育期温度适宜度最高、日照适宜度次之、降水适宜度最低,水分是冬小麦生长的限制因子。气候综合适宜度灌浆-乳熟期最高,分蘖期降水适宜度最低,并且其序列变异系数大,常遭遇秋冬连旱,引起产量波动;全生育期气候适宜度呈东高西低分布,淮北中东部较高,而淮北西部及沿淮地区较低,冬小麦生产风险相对较高。1961-2016年全生育期温度适宜度线性增大趋势显著,降水适宜度线性趋势不明显,而日照适宜度呈显著的线性减小趋势;综合来看,全生育期气候适宜度无明显线性增减趋势,空间上淮北东部略有增大,而西部及沿淮地区略有减小,气候风险增加。淮北平原多数年份气候适宜度适中,适宜性偏差年发生概率高于偏好年。基于气候适宜度评判冬小麦气候年景等级,评估结果与实际产量增减情况基本相符,表明农业气候年景模型评估精度能满足业务服务需求,具有推广应用价值。     

藏南柯月铅锌矿床成矿物质来源:来自硫、铅同位素的证据

藏南柯月铅锌矿床位于特提斯喜马拉雅构造域Sb-Au-Pb-Zn成矿带东段,矿体主要呈透镜状或脉状,严格受北东向断裂构造所控制,赋矿地层为下侏罗统日当组含碳钙质板岩。矿石硫化物硫同位素δ~(34)S介于9.2‰~11.2‰之间,平均值为9.85‰,与区内日当组地层的δ~(34)S值变化范围相似,表明成矿流体中的硫主要来源于容矿地层。矿石硫化物铅同位素组成为:~(206)Pb/~(204)Pb为19.669~19.813,平均值19.740;~(207)Pb/~(204)Pb为15.823~15.979,平均值15.902;~(208)Pb/~(204)Pb为40.104~40.687,平均值40.410。其结果显示,矿石中的铅具有高放射性成因铅的特征,与喜马拉雅结晶基底的铅同位素组成具有相似的比值,表明矿石铅主要来源于喜马拉雅结晶基底。     

福建三明万寿岩地区中更新世晚期以来地壳多期隆升特征及地质意义

为研究福建三明万寿岩地区的新构造运动特征,本次研究以区内两级层状洞穴和两级河流阶地为研究对象,通过对洞穴和阶地的详细剖面测量,结合洞穴和阶地的年龄,认为万寿岩地区从中更新世晚期以来至少经历了四次隆升:262 ka前为第一隆升期,185~37 ka为第二隆升期,37~17.4 ka为第三隆升期,10.4 ka以来为第四隆升期。其中前两次间歇期分别形成灵峰洞和船帆洞,后两次隆升期分别形成鱼塘溪的二级阶地和一级阶地。262 ka以来隆升速率的计算结果显示,万寿岩地区各时期隆升速率相差较大,但总体活动强度较弱。万寿岩地区间歇性隆升与福建东部沿海地区地壳沉降形成鲜明反差,表明福建境内的新构造运动具有差异性升降特征。     

Study on Sound-Speed Dispersion in A Sandy Sediment at Frequency Ranges of 0.5-3 kHz and 90-170 kHz

In order to study the properties of sound-speed dispersion in a sandy sediment, the sound speed was measured both at high frequency (90-170 kHz) and low frequency (0.5-3 kHz) in laboratory environments. At high frequency, a sampling measurement was conducted with boiled and uncooked sand samples collected from the bottom of a large water tank. The sound speed was directly obtained through transmission measurement using single source and single hydrophone. At low frequency, an in situ measurement was conducted in the water tank, where the sandy sediment had been homogeneously paved at the bottom for a long time. The sound speed was indirectly inverted according to the traveling time of signals received by three buried hydrophones in the sandy sediment and the geometry in experiment. The results show that the mean sound speed is approximate 1710-1713 m/s with a weak positive gradient in the sand sample after being boiled (as a method to eliminate bubbles as much as possible) at high frequency, which agrees well with the predictions of Biot theory, the effective density fluid model (EDFM) and Buckingham''s theory. However, the sound speed in the uncooked sandy sediment obviously decreases (about 80%) both at high frequency and low frequency due to plenty of bubbles in existence. And the sound-speed dispersion performs a weak negative gradient at high frequency. Finally, a water-unsaturated Biot model is presented for trying to explain the decrease of sound speed in the sandy sediment with plenty of bubbles.     

航空多光谱图像地形影响校正的模拟反射率方法

开展强起伏地形等复杂条件下的多光谱数据处理实用方法研究,是使中高山地区多光谱定量化解释成果水平取得明显提高的重要途径之一。本文根据地形因素对航空多光谱图像地质解释影响的特点、多光谱仪的成像方式,应用简化的太阳辐射能量平衡原理,研究了如何从航空多光谱图像像元的亮度变化中消除地形影响,模拟生成反射率图像的新方法。新方法综合考虑了地表太阳辐照度的变化、地物的光谱反射率、反照率和热辐射信息,与目前常规的处理技术(如比值法和剩余对数法) 相比,消除了地形坡度和坡向变化对图像解释的影响,保留了地物反照率信息,为多光谱定量化解释提供了更合理有效的反射率图像,对超光谱数据的处理和解释均有潜在的应用价值。     

地震矩张量反演在地震观测报告中的应用

针对我国地震工作的实际需要,从１９９５年起,《中国地震台网目录和地震矩张量解》刊登了国内较大地震和全球大震的地震矩张量解和震源机制解。同时在《中国地震年报》上也刊登国内及邻区较大地震的地震长张量解和震源机制解。为了方便用户使用,本文对有关参数进行了说明。     

江西万载县罗城铜矿地质特征及找矿前景

罗城铜矿区处于九岭南缘大型推(滑)覆构造往南突出的前锋与NNE向走滑冲断带复合部位.经大比例尺土壤地球化学和激电剖面测量,圈定出Cu-Zu异常与激电异常多处,经深部工程验证,已控制Ⅰ号铜矿带东段4条铜矿体,铜资源量可达中型,矿体均产于中元古代宜丰岩组含Cu古火山岩矿源层中,并受强烈韧性剪切带内滑脱断裂带的控制.Ⅰ号铜矿带西部Cu-Zu异常更为广泛,南部Ⅱ号铜矿带也存在Cu-Zu异常与激电异常多处,具有形成大型矿床的资源潜力.     

极区顶部电离层离子上行-DMSP卫星观测

本文利用DMSP卫星离子漂移速度测量数据,对高纬顶部电离层离子整体上行进行研究,主要考察平静时和磁暴期间离子上行强度与发生率随MLT(晨昏两侧)分布规律的变化;以及磁暴期间强的离子上行与等离子体对流及其剪切之间的关系。研究发现,磁暴期间强上行事件的发生率比平静期高近2倍,发生率的晨昏不对称性出现逆转,由平静时昏侧发生率较大变为磁暴期间晨侧发生率较大;磁暴期间晨侧离子上行速度的分布向速度高端加权,平均速度大于昏侧,最大上行速度远大于昏侧;强的离子上行往往与强对流剪切或强对流本身相伴随。     

米仓山-大巴山前陆盆地下沙溪庙组高分辨率层序地层学特征

通过基准面旋回结构、叠加样式的沉积动力学分析．结合地表露头、钻井岩芯、测井资料的综合研究,运用高分辨率层序地层学理论和技术方法将米仓山-大巴山前陆盆地中侏罗统下沙溪庙组划分为1个长期、2个中期和10余个短期旋回层序;较为详细地讨论了短期、中期和长期旋回层序的结构类型、沉积序列和叠加样式;建立以长期旋回层序界面和最大洪泛面为等时地层格架,以中期旋回层序为等时地层单元的层序地层格架,以及地层格架中生储盖组合特征,认为下沙溪庙组下部具备良好的油气储、盖组合和形成大、中型次生油气藏的务件。