青藏高原湖泊面积动态监测

高原湖泊的动态变化对区域水循环具有重要影响。受全球气候变化的影响,青藏高原湖泊自20世纪90年代开始呈现剧烈扩张趋势。为揭示近年来青藏高原湖泊面积的时空变化规律,本文提出了一种改进的半自动湖泊提取算法,结合环境减灾卫星（HJ-1A/1B）和Landsat系列卫星影像数据,对青藏高原内流流域中面积大于50 km²的127个湖泊进行了连续6年的动态监测,并分析了该区域2009-2014年湖泊面积时空变化特征。研究结果表明,该区域湖泊整体呈现显著扩张趋势,年均变化速率为231.89 km²yr^-1（0.87 %yr^-1）,6年间湖泊面积扩张速率有所减缓。其中,扩张湖泊有104个,收缩湖泊有23个,变化速率分别为271.08 km²yr^-1（1.02 % yr^-1）和-39.19 km²yr^-1（-0.15 %yr^-1）。不同区域湖泊面积变化具有明显差异,主要表现为东部及北部大部分区域湖泊扩张,南部地区大部分湖泊面积稳定,萎缩湖泊主要分布于研究区四周。最后,本文通过分析冰川融水补给对湖泊面积变化的影响,发现存在冰川融水补给的湖泊面积变化率远大于不存在冰川融水补给的湖泊。由此可见,近年来冰川融水的增加是促进青藏高原内流流域湖泊扩张的主要因素之一。     

西藏亚东-谷露裂谷带运动特征的InSAR研究

亚东-谷露裂谷等南北向分布的大型地堑在青藏高原新生代构造演化中发挥着重要作用,该研究对理解青藏高原中南部地堑在第四纪构造演化的地位具有重要意义。基于欧空局Envisat卫星2003~2008年SAR数据,利用SBAS时序InSAR技术,去除地形、大气、轨道等因素的影响,获取亚东-谷露裂谷带及邻区的LOS速度场,并反演亚东-谷露裂谷带的滑动速率和闭锁深度。结果表明,亚东-谷露裂谷带南段与北段具有相同的倾滑速率,均为1 mm/a;其闭锁深度南段为31 km,北段为22 km;其断层倾角南段为52°,北段为40°,与地质结果一致。     

Comparison of LiDAR waveform processing methods for very shallow water bathymetry using Raman,near‐infrared and green signals

Airborne light detection and ranging (LiDAR) bathymetry appears to be a useful technology for bed topography mapping of non‐navigable areas, offering high data density and a high acquisition rate. However, few studies have focused on continental waters, in particular, on very shallow waters (<2 m) where it is difficult to extract the surface and bottom positions that are typically mixed in the green LiDAR signal. This paper proposes two new processing methods for depth extraction based on the use of different LiDAR signals [green, near‐infrared (NIR), Raman] of the SHOALS‐1000T sensor. They have been tested on a very shallow coastal area (Golfe du Morbihan, France) as an analogy to very shallow rivers. The first method is based on a combination of mathematical and heuristic methods using the green and the NIR LiDAR signals to cross validate the information delivered by each signal. The second method extracts water depths from the Raman signal using statistical methods such as principal components analysis (PCA) and classification and regression tree (CART) analysis. The obtained results are then compared to the reference depths, and the performances of the different methods, as well as their advantages/disadvantages are evaluated. The green/NIR method supplies 42% more points compared to the operator process, with an equivalent mean error (?4·2 cm verusu ?4·5 cm) and a smaller standard deviation (25·3 cm verusu 33·5 cm). The Raman processing method provides very scattered results (standard deviation of 40·3 cm) with the lowest mean error (?3·1 cm) and 40% more points. The minimum detectable depth is also improved by the two presented methods, being around 1 m for the green/NIR approach and 0·5 m for the statistical approach, compared to 1·5 m for the data processed by the operator. Despite its ability to measure other parameters like water temperature, the Raman method needed a large amount of reference data to provide reliable depth measurements, as opposed to the green/NIR method. Copyright © 2010 John Wiley & Sons, Ltd.     

SCALES: a large‐scale assessment model of soil erosion hazard in Basse‐Normandie (northern‐western France)

The cartography of erosion risk is mainly based on the development of models, which evaluate in a qualitative and quantitative manner the physical reproduction of the erosion processes (CORINE, EHU, INRA). These models are mainly semi‐quantitative but can be physically based and spatially distributed (the Pan‐European Soil Erosion Risk Assessment, PESERA). They are characterized by their simplicity and their applicability potential at large temporal and spatial scales. In developing our model SCALES (Spatialisation d'éChelle fine de l'ALéa Erosion des Sols/large‐scale assessment and mapping model of soil erosion hazard), we had in mind several objectives: (1) to map soil erosion at a regional scale with the guarantee of a large accuracy on the local level, (2) to envisage an applicability of the model in European oceanic areas, (3) to focus the erosion hazard estimation on the level of source areas (on‐site erosion), which are the agricultural parcels, (4) to take into account the weight of the temporality of agricultural practices (land‐use concept). Because of these objectives, the nature of variables, which characterize the erosion factors and because of its structure, SCALES differs from other models. Tested in Basse‐Normandie (Calvados 5500 km²) SCALES reveals a strong predisposition of the study area to the soil erosion which should require to be expressed in a wet year. Apart from an internal validation, we tried an intermediate one by comparing our results with those from INRA and PESERA. It appeared that these models under estimate medium erosion levels and differ in the spatial localization of areas with the highest erosion risks. SCALES underlines here the limitations in the use of pedo‐transfer functions and the interpolation of input data with a low resolution. One must not forget however that these models are mainly focused on an interregional comparative approach. Therefore the comparison of SCALES data with those of the INRA and PESERA models cannot result on a convincing validation of our model. For the moment the validation is based on the opinion of local experts, who agree with the qualitative indications delivered by our cartography. An external validation of SCALES is foreseen, which will be based on a thorough inventory of erosion signals in areas with different hazard levels. Copyright © 2010 John Wiley & Sons, Ltd.     

���������������¶�λ�������

????????λ???????????(111??120??E??35??42??N)1993??2004??6 771?ε???1.0??M??6.6???????λ???????λ???????????????????????????????????????????????;???o?????·???????????????????????????б???????????????????????????????????20 km????60 km???????25 km??34 km?????40 km;83%???????????λ??0??15 km??Χ?????????????λ???????????????(7??21 km)????????????????????????????????????????????????;???92%???????????λ??1??24 km??????24 km??????????????????????硣     

哈尔滨市松北区水库雍水浸没评价

浸没问题是平原型水库主要地质灾害之一。在分析了哈尔滨市松北区雍水浸没成控因素的基础上,采用地下水流数值模拟技术对研究区在不同开采方案下的雍水浸没进行评价,并综合考虑区内的地表覆盖情况、建筑物地基形式等因素,提出了适合研究区水文地质条件的浸没标准：农田区为粉质粘土2.50 m, 粉细砂1.50 m;建筑物区为粉质粘土3.50 m,粉细砂3.00 m。将研究区划分为可能浸没区、过渡浸没区和不发生浸没区,并确定了各浸没区的范围。     

浅埋隧道围岩应力场的计算复变函数求解法

对于受地表边界和地面荷载影响的浅埋隧道的围岩应力场,由于在数学处理上存在一定的困难,很难用解析解来进行分析,而通常采用边界元或有限元的数值方法来解答。为了求解浅埋隧道的应力场,采用边界配点来确定边界条件,同时用保角映射将一个含圆孔的半无限空间区域映射为圆环域,然后把这个区域内的解析函数展开成Laurent级数的形式,利用Muskhelishvili的复变函数理论和最小二乘法来确定解析函数的各项系数,从而求得浅埋隧道围岩压力的半数值、半解析解,最后通过算例给出了围岩应力的分布情况。计算结果表明,该方法计算精度高、计算量小,具有应用价值。     

Consensus maps of cloned plant cuticle genes

Plant cuticle,which covers the plant surface,consists of waxes and cutins,and is associated with plant drought,cold,and salt resistance.Hitherto,at least 47 genes participating in the formation of plant cuticle have been cloned from Arabidopsis thaliana,Oryza sativa,Zea mays,Ricinus communis,Brassica napus,and Medicago truncatula;and about 85% of them encode proteins sharing above 50% identities with their rice homologous sequences.These cloned cuticle genes were mapped in silico on different chromosomes of rice and Arabidopsis,respectively.The mapping results revealed that plant cuticle genes were not evenly distributed in both genomes.About 40% of the mapped cuticle genes were located on chromosome 1 in Arabidopsis,while 20% of the mapped cuticle genes were located on chromosome 2 but none on chromosome 12 in rice.Some cloned plant cuticle genes have several rice homologous sequences,which might be produced by chromosomal segment duplication.The consensus map of cloned plant cuticle genes will provide important clues for the selection of candidate genes in a positional cloning of an unknown cuticle gene in plants.     

围岩作用下锚杆砂浆锈胀开裂过程分析

从砂浆锚杆锚固体自身的特点出发,借鉴钢筋混凝土结构锈胀开裂研究成果,对锚杆砂浆锈胀开裂过程进行了分析。考虑锚杆锈蚀体积膨胀过程,以填充系数表示砂浆开裂过程中锚杆锈蚀产物的损失,建立了锚杆锈蚀后砂浆内部位移模型,以弹性力学为基础,引入围岩参数影响系数概念,对锚杆锈蚀导致砂浆保护层开裂过程以及围岩参数对开裂过程的影响程度等进行了分析研究,并采用有限元分析方法对其进行了验证。理论分析结果表明,因锚杆锈蚀而导致的砂浆保护层开裂以及裂纹的扩展情况均与围岩特性密切相关,砂浆开裂后裂纹会经历一段稳定扩展过程,裂纹的最大稳定扩展半径随围岩参数影响系数的增加而增大,在合适的围岩参数条件下,裂纹可以一直稳定扩展致整个砂浆保护层外壁。有限元分析结论与理论结果一致。     

挡土墙主动土压力塑性临界深度的解析解

墙后塑性区的临界深度问题一直没有得到很好解决,传统计算公式仅适用于一些特殊情况。基于极限平衡理论,视墙后填土为服从Mohr-Coulomb屈服准则的理想弹塑性材料,假定塑性区的一族滑移线为直线即平面滑裂面,提出弹性覆盖层取代传统的张拉裂缝,建立了较为完善的滑楔分析模型,采用极限平衡法推导了在一般情况下的塑性临界压力、临界深度以及塑性区可能最大深度的解析解。计算结果表明,塑性临界深度的解析解与目前文献采用迭代计算的结果完全一致,传统计算公式是该解析解的一个特例。