Measuring bluff erosion part 1: terrestrial laser scanning methods for change detection

Human activities influence watershed sediment dynamics in profound ways, often resulting in excessive loading of suspended sediment to rivers. One of the primary factors limiting our ability to effectively manage sediment at the watershed scale has been our inability to adequately measure relatively small erosion rates (on the order of millimeters to centimeters per year) over annual and sub‐annual time scales on spatially‐extensive landforms, such as river banks and bluffs. Terrestrial laser scanning (TLS) can be employed to address this need. TLS collects high‐resolution data allowing for more accurate monitoring of erosion rates and processes, and provides a new opportunity to make precise measurements of geomorphic change on vertical landforms like banks and bluffs, but challenges remain. This research highlights challenges and limitations of using TLS for change detection on river banks and bluffs including the presence of vegetation, natural surface crenulations, and difficulties with creating benchmarks, and provides solutions developed to overcome these limitations. Results indicate that data processing algorithms for change detection can have a significant impact on the calculated erosion rates, with different methods producing results that can vary by over 100%. The most accurate change detection technique compares a point cloud to a triangulated irregular network (TIN) along a set of vectors that accommodate bluff curvature. This paper outlines a variety of methods used to measure bluff change via TLS and explains the accompanying error analysis that supports these methods. Copyright © 2012 John Wiley & Sons, Ltd.     

On a new condition for directions of a spatial network

Zusammenfassung Es wird eine neue Bedingung, Gl. (6), angeführt, die von den bereits ausgeglichenen, z. B. durch den Stundenwinkel t und die Deklination δ definierten Richtungen der Seiten des Raumnetzes erfüllt werden muss. Zur Demonstration dieser Bedingung wird ein Modell des Raumnetzes in der Form eines Tetraeders benutzt (Abb. 1).

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Address: Karlovo nám. 13, Praha 2.     

高压变电站抗震可靠性分析(一)

讨论了高压变电站中电气主接线系统的抗震可靠性分析问题,主要分析了高压变电站中常见的双母线系统的抗震可靠性。通过系统的可靠性关系和建立系统的可靠性分析准则,给出了双母线系统在各个抗震准则条件下的可靠性的表达形式。最后进行了实例分析。     

Determination of crustal movements in Turkey by terrestrial geodetic methods

In Turkey, neotectonic activity originated from the collision of the Arabian and Anatolian land masses during the Middle Miocene. As a result of the collision, westward escape of the Anatolian block introduced E-W compression in Western Turkey which began to be relieved by N-S extension. The North Anatolian Fault (NAF) is the major active strike-slip fault that was formed under the neotectonic regime. The rates of the motion along this fault estimated by several authors are in the range of 0.4–2.9 cm/a according to kinematic data. In Turkey, the first studies of crustal movements by geodetic methods were started in the west section of the NAF in 1972. So far, individual activities and studies coordinated by multidisciplinary projects have been realized in this region. The results obtained from available geodetic data indicate the motion of the Anatolian block relative to Eurasia.     

A big-data spatial,temporal and network analysis of bovine tuberculosis between wildlife (badgers) and cattle

Bovine tuberculosis (TB) poses a serious threat for agricultural industry in several countries, it involves potential interactions between wildlife and cattle and creates societal problems in terms of human-wildlife conflict. This study addresses connectedness network analysis, the spatial, and temporal dynamics of TB between cattle in farms and the European badger (Meles meles) using a large dataset generated by a calibrated agent based model. Results showed that infected network connectedness was lower in badgers than in cattle. The contribution of an infected individual to the mean distance of disease spread over time was considerably lower for badger than cattle; badgers mainly spread the disease locally while cattle infected both locally and across longer distances. The majority of badger-induced infections occurred when individual badgers leave their home sett, and this was positively correlated with badger population growth rates. Point pattern analysis indicated aggregation in the spatial pattern of TB prevalence in badger setts across all scales. The spatial distribution of farms that were not TB free was aggregated at different scales than the spatial distribution of infected badgers and became random at larger scales. The spatial cross correlation between infected badger setts and infected farms revealed that generally infected setts and farms do not coexist except at few scales. Temporal autocorrelation detected a two year infection cycle for badgers, while there was both within the year and longer cycles for infected cattle. Temporal cross correlation indicated that infection cycles in badgers and cattle are negatively correlated. The implications of these results for understanding the dynamics of the disease are discussed.     

Thermoluminescence and the terrestrial age of meteorites: Some recent results

This paper reports the results of an examination of the thermoluminescence (TL) of 23 meteorites which were observed to fall, and 17 meteorite finds which have had their terrestrial age determined by the¹⁴C method. The terrestrial ages of the observed falls range from 1 to 205 years, whilst the¹⁴C terrestrial ages range from 1200 ± 2000 to >20,000 years. A statistically significant correlation has been observed between the natural TL — as expressed as the ratio of the intensity of the low-temperature TL peak to that of the high-temperature peak — and the terrestrial age of the 40 meteorites. Furthermore, peak height ratios in excess of 3.0 are only observed in falls which fell within the last 250 years, suggesting that finds with peak height ratios as large as this, such as Allan Hills A77003 and Plainview (1917), fell within the last few hundred years. The present results are consistent with evidence that meteorite TL decay is a non-first-order process. The implications of the results for estimates of the terrestrial ages of 8 meteorite finds, for which there are no¹⁴C data, are also discussed.     

中越红河断裂带考察与研究（一）

基于对越南境内红河断裂带的野外考察,结合中国境内红河断裂带已有考察研究成果,从断裂几何结构、构造演化与地层发育、新生代地质地貌特征等多个方面,初步探讨了红河断裂带现今活动的基本特征.认为:(1)红河断裂带在断裂几何结构、断裂长期的发育演化过程、断裂活动的地质地貌表现等诸多方面都表现出异常突出的时空不均匀性和分段性;(2)红河断裂新构造运动以来的夷平面发育与解体、新生代盆地发育与堆积、水系及河流阶地发育与变形等方面的特征表明,中国境内红河断裂带第四纪以来总体活动水平由北向南逐渐减弱的趋势一直延续到了越南境内;(3)青藏高原侧向挤出作用的影响范围足有限的,这一认识对于探索川滇地区地壳运动与强震活动的动力学机制具有重要意义.     

查尔斯·里克特(之二)

在本文上半部分中,福里斯特博士回顾了里克特的童年、受教育情况和里氏震级的发展。在下半部分,他为我们展示了作为凡人和科学家的里克特在其鼎盛时期及以后的生活。福里斯特博士大量引用了保存于加州理工学院档案馆中的里克特的文章。该档案馆曾慷慨地允许作者在这里利...     

查尔斯·里克特(之一)

从本期开始,我们分两部分为大家介绍一位在公众意识当中与地震紧密相关的人物,他的名字就是查尔斯·里克特（ＣｈａｒｌｅｓＲｉｃｈｔｅｒ）。这一部分有关里克特故事的时间跨度为１９００～１９３７年,包括里克特的童年,他在加州理工学院的早年生活,以及长滩地震。...     

Quantification of nitrate storage in the vadose (unsaturated) zone: a missing component of terrestrial N budgets

National terrestrial nitrogen budgets for many developed countries have been calculated as part of the management of impacts of N on the environment, but these rarely represent the subsurface explicitly. Using estimates of vadose zone travel time and agricultural nitrate loading, we quantify, for the first time, the total mass of nitrate contained in the vadose zone of aquifers in England and Wales. This mass peaked in 2008 at 1400 kt N (800 to >1700 kt N from sensitivity analyses), which is approximately 2.5 to 6 times greater than saturated zone estimates for this period and indicates that the subsurface is an important store of reactive nitrogen. About 70% of the nitrate mass is estimated to be in the Chalk, with the remainder split between the Permo‐Triassic sandstones, the Jurassic Oolitic limestones and minor aquifers. Current controls on fertilizer application mean that the vadose zone is now a nitrate source, and in 2015 we estimate the net flux from the unsaturated zone to groundwater to be 72 kt N/a. The mass of nitrate in the vadose zone should be included in future terrestrial nitrogen budgets at national and global scales to improve ecosystem management. British Geological Survey © NERC 2015. Hydrological Processes © 2015 John Wiley & Sons, Ltd.     

Evaluation of digital channel network derivation methods in a glaciated subalpine catchment

The digital elevation model (DEM) has become an essential tool for an increasing array of mountain runoff analyses, particularly the derivation and mapping of stream channel networks. This study examines how well commonly applied DEM‐based channel derivation methods at different spatial resolutions can represent the channel network for a glaciated Rocky Mountain headwater catchment. The specific objectives are to (1) examine how differences in gridded DEM resolution affect spatially distributed values of local slope, specific contributing area, and topographic wetness index derived from both eight and infinite directional flow algorithms, (2) map the actual stream channel network to examine the influence of surface variables on channel initiation, and (3) assess accuracy of DEM‐derived networks compared with the field surveyed network. Results show that for the same contributing area threshold, increasing grid cell size leads to increased channelization of modeled networks. A plot of local slope versus contributing area reveals a negative relationship similar to that of prior studies in un‐glaciated areas but with breaks in slope at contributing areas that are too small to represent thresholds for channelization. Field survey results and evaluation of DEM‐derived channel networks suggest that channel network formation is not clearly related to surface topographic variables at Loch Vale. Digitally derived channel networks do not accurately predict low order channel locations, but approximations of the channel network with drainage density and headward extent of channelization similar to the observed network can be derived with both a 1 m and 10 m DEM using a contributing area threshold of approximately 4x10⁴ m². Copyright © 2014 John Wiley & Sons, Ltd.     

The role of rainfall temporal and spatial averaging in seasonal simulations of the terrestrial water balance

The partitioning of rainfall into surface runoff and infiltration influences many other aspects of the hydrologic cycle including evapotranspiration, deep drainage and soil moisture. This partitioning is an instantaneous non-linear process that is strongly dependent on rainfall rate, soil moisture and soil hydraulic properties. Though all rainfall datasets involve some degree of spatial or temporal averaging, it is not understood how this averaging affects simulated partitioning and the land surface water balance across a wide range of soil and climate types. We used a one-dimensional physics-based model of the near-surface unsaturated zone to compare the effects of different rainfall discretization (5-min point-scale; hourly point-scale; hourly 0.125° gridded) on the simulated partitioning of rainfall for many locations across the United States. Coarser temporal resolution rainfall data underpredicted seasonal surface runoff for all soil types except those with very high infiltration capacities (i.e., sand, loamy sand). Soils with intermediate infiltration capacities (i.e., loam, sandy loam) were the most affected, with less than half of the expected surface runoff produced in most soil types when the gridded rainfall dataset was used as input. The impact of averaging on the water balance was less extreme but non-negligible, with the hourly point-scale predictions exhibiting median evapotranspiration, drainage and soil moisture values within 10% of those predicted using the higher resolution 5-min rainfall. Water balance impacts were greater using the gridded hourly dataset, with average underpredictions of ET up to 27% in fine-grained soils. The results suggest that “hyperresolution” modelling at continental to global scales may produce inaccurate predictions if there is not parallel effort to produce higher resolution precipitation inputs or sub-grid precipitation parameterizations.     

灾害对策实例 (之二)

2　台湾地震发生之后的对策2 .1　当局的反应在台湾 ,由于控制灾害的主体是台湾当局 ,因而形成一个集权化系统 ,震灾之后由台湾当局组建机构和实施计划。2 .2　紧急措施2 .2 .1　信息与公共事务工作信息收集方面 ,由于道路和通讯网的阻断等诸缘故 ,山区不能与外界取得通讯联系 ,没有办法无延迟地掌握其破坏情况。信息传递和公共事务工作方面 ,可通过各种途径获得即时行动情况和确切信息。“行政院”在地震发生之后于 9月 2 5日立即作出一个包括给付慰问金的 1 9条紧急救济措施的决定。值得提出的是 ,条款包括了紧急响应 ,如给付死亡和房屋完…     

灾害对策实例(之一)

为了加强未来的减灾措施 ,了解受害国家和国际社会如何处理过去的灾害是极为重要的。在 1 998财政年度 ,我们收集了阪神·淡路大地震和因特网上一些灾害的对策实例。在1 999年这一财政年度 ,我们已经收集了袭击土耳其和台湾的地震灾害对策实例。1　土耳其大地震后采取的措施1 .1　地震概况1 )地震日期和时间 :1 999年 8月 1 7日当地时间上午 0 3时 0 1分 ;2 )震级 :里氏 7.4级 ;3 )死亡人数 :1 51 3 5人 ;4)失踪人数 :未知 ;5)受伤人数 :约 2 40 0 0人 (医院统计数 ) ;6)完全损坏房屋数 :约 2 40 0 0栋 ;7)部分损坏房屋数 :约 64 0 0 0栋。1…     

Mercury Circulation in Aquatic Bioconeses. Part 1: Mercury (II)-Metabolism in Phytoplankton

The metabolism of inorganic mercury has been studied in stationary cultures of planktonic algae Chlorella kessleri, Scenedesmus obliquus and Microcystis incerta that were exposed for 14 days to the concentration of 2 × 10^?7 M of Hg(II). Individual chemical forms of mercury were determined in algae and in the culture medium at regular intervals. All the studied phytoplankton species started to metabolize mercury immediately after its application, with the exception of the blue-green alga Microcystis incerta. The accumulation of mercury proceeds without interruption till the end of the experiment. After a 14 days cultivation about 60… 80% of added mercury was present in algal cells and the portion of mercury washable from the cell surface did not exceed 2%. It was found that more than 99,5% of mercury in cultivation medium and more than 99,5% of mercury in algae was present in the form of Hg(II). A transformation of inorganic mercury to methyl-, or phenyl-mercury due to the action of algae was not observed.     

中法合作数字化台网—张掖台网简介

数字化微震台网在国内是第一次尝试。张掖台网是中法合作的数字化台网，通过实践表明，台网的资料是可靠的，为国内地震研究手段开辟了新的领域。