Research and application in British geomorphology

Three aspects of the application of geomorphological research are identified: direct application of principles, methods and techniques; research and development specifically for application and the recognition of potentially applicable research. Some recent British work in each of these areas is reviewed.     

DEM在构造地貌定量分析中的应用与展望

作为一种描述地形起伏特征的数据模型,数字高程模型（Digital Elevation Model,DEM）通过有限的地形高程数据实现对地形曲面的数字化模拟（即地形表面形态的数字化表示）,为研究地表的演化过程提供了数据基础。文章归纳梳理了DEM在基本地形因子、流域地貌特征、古地貌面的重塑、构造地貌发育模式、地貌分类与制图以及地形特征提取算法等领域的应用现状。总的来看,DEM研究对象以陆地为重点,以河流地貌和山地地貌为主要内容;研究过程从早期对地貌形态的定性描述向多种地貌参数的半定量、定量分析转变;研究尺度空间上从某个小流域到整个造山带,时间上从数小时向百万年扩展。构造地貌演化时间序列的不确定性、地貌参数获取的复杂性、地形模型算法的多样化以及DEM生成过程中的误差因素,这些均影响构造地貌定量分析结果的准确度,因此在归纳梳理已有研究成果的同时,对DEM在构造地貌研究领域的应用进行了一些思考。      

Geomorphological patterns in a linear dune field and ages of the linear dunes in the northern Kumtagh Desert, northwest China

The unique linear dunes in the northern Kumtagh Desert of northwest China have inspired enthusiastic debate among aeolian geomorphologists over their origins and classification. Their uniqueness lies not only in their morphology, but also in their geomorphological patterns. In this paper, the geomorphological patterns and ages of the linear dunes in the northern Kumtagh Desert are analyzed using the pattern analysis method that was recently adopted by geomorphologists. The analysis suggests that these linear dunes have developed since 13 ka BP, during the late part of the most recent deglaciation stage, when the region’s dry climate was favorable for dune formation. The differences in dune construction time within this region result from the complex factors that control their formation and spatial variations in the local environment, but these factors were not strong enough to prevent us from estimating the dune age recorded by the geomorphological patterns with acceptable precision. It is also suggested that the pattern analysis method can be used to estimate dune ages in the absence of more reliable dating methods.     

Logistic regression versus artificial neural networks: landslide susceptibility evaluation in a sample area of the Serchio River valley,Italy

This article presents a multidisciplinary approach to landslide susceptibility mapping by means of logistic regression, artificial neural network, and geographic information system (GIS) techniques. The methodology applied in ranking slope instability developed through statistical models (conditional analysis and logistic regression), and neural network application, in order to better understand the relationship between the geological/geomorphological landforms and processes and landslide occurrence, and to increase the performance of landslide susceptibility models. The proposed experimental study concerns with a wide research project, promoted by the Tuscany Region Administration and APAT-Italian Geological Survey, aimed at defining the landslide hazard in the area of the Sheet 250 “Castelnuovo di Garfagnana” (1:50,000 scale). The study area is located in the middle part of the Serchio River basin and is characterized by high landslide susceptibility due to its geological, geomorphological, and climatic features, among the most severe in Italy. Terrain susceptibility to slope failure has been approached by means of indirect-quantitative statistical methods and neural network software application. Experimental results from different methods and the potentials and pitfalls of this methodological approach have been presented and discussed. Applying multivariate statistical analyses made it possible a better understanding of the phenomena and quantification of the relationship between the instability factors and landslide occurrence. In particular, the application of a multilayer neural network, equipped for supervised learning and error control, has improved the performance of the model. Finally, a first attempt to evaluate the classification efficiency of the multivariate models has been performed by means of the receiver operating characteristic (ROC) curves analysis approach.     

Bringing geoheritage underwater: definitions,methods, and application in two Mediterranean marine areas

Within the definition given by UNESCO of World Cultural and Natural Heritage, geoheritage finds its significance both as the geological or geomorphological elements of nature worthy of conservation and as habitat of threatened species of outstanding universal value from the point of view of science or conservation. Definitions, methods, and applications for the conservation and valorization of geoheritage have been proposed for various types of environments, but their application in underwater areas is seldom, if even, reported. In this study, we propose a set of definitions and methods for the evaluation of scientific and additional values in underwater environment, and we apply them in two Mediterranean areas: Sigri (Greece, Lesvos Island) and Bergeggi (Italy, Liguria region). Results show the applicability of the schemes proposed in different geological and geomorphological settings and provide tools for the evaluation of abiotic underwater heritage in the two areas.     

Research Status and Application Prospect of Shelf-Edge Trajectory Analysis

Trajectory analysis is the hotspot and research frontier of sedimentology and sequence stratigraphy. Compared with conventional analytical methods, trajectory analysis is aiming at identifying sedimentary systems and predicting sandstone reservoirs more directly. The definition of trajectory analysis has been made by Helland-Hansen as “The study of the lateral and vertical migration of geomorphological features and associated sedimentary environments, with emphasis on the paths and directions of migration”. Based on current research progress, the basic concepts and methods of trajectory analysis, types of basinward-migrating trajectories (ascending, flat and descending), quantitative parameters and the application in predicting deep-water sandstone reservoirs were introduced. Trajectory analysis mainly centers on two scales: Shoreline trajectories and shelf-edge trajectories. The formation of basin-floor fans has close relation with shelf-edge trajectories, and multiple case studies have confirmed that large-scale basin floor fan usually form under flat or descending shelf-edge trajectories. As research advances, trajectory analysis theory, which developed in continental margins, is believed to have been influenced by multiple factors. Thus, the accurate prediction of sandstone reservoirs requires the comprehensive consideration of the influence of sediment supply, accommodation spaces, past climate and so on. In addition, the problems and extensions of trajectory analysis were also introduced, including ①the along-strike lateral differential evolution; ② trajectory analysis theory in hydrological-closed sedimentary basins; ③the application of trajectory analysis in carbonate settings. As a developing theory, the terminology of trajectory analysis still needs standardization, and the coupling between shelf-edge trajectories and the development and distribution of deep-water sandstones also needs further understanding. The next research focus could be placed on interpreting the evolution of three-dimensional sedimentary systems, and the extension of shelf-edge trajectory theory to hydrologically-closed basin and carbonate sedimentary environments. The research methods of trajectory analysis should also follow the newest trends to allow researchers to better study the evolution of shelf-edge trajectories, for instance, integrating high-resolution seismic data and logging data, core samples, outcrops and high-resolution dating techniques to describe ancient sedimentary environment and geomorphology, combining satellite imaging, ground penetrating radar to portray the modern morphology of continental margins, and utilizing remote sensing to construct more precise three-dimensional models for outcrops.     

FIRST EXTENDED PLENUM OF THE INTERDEPARTMENTAL COMMISSION ON GEOMORPHOLOGY,DIVISION OF GEOLOGIC AND GEOGRAPHIC SCIENCES,ACAD. OF SCIENCES OF THE U.S.S.R.

Among the topics covered by the 12th plenary meeting of the Commission of Geomorphology were 1) status of geomorphological research and mapping in the U.S.S.R., 2) application of geomorphology in construction and mineral prospecting, 3) geomorphological training, and 4) standardization of mapping procedures and symbolism. The plenum went on record as favoring maps based primarily on genetic classification of features.—M. Russell.     

Geometric and kinematic characterization of landslides affecting urban areas: the Lungro case study (Calabria,Southern Italy)

The geometric and kinematic characterization of landslides affecting urban areas is a challenging goal that is routinely pursued via geological/geomorphological method and monitoring of ground displacements achieved by geotechnical and, more recently, advanced differential interferometric synthetic aperture radar (A-DInSAR) data. Although the integration of all the above-mentioned methods should be planned a priori to be more effective, datasets resulting from the independent use of these different methods are commonly available, thus making crucial the need for their standardized a posteriori integration. In this regard, the present paper aims to provide a contribution by introducing a procedure that, taking into account the specific limits of geological/geomorphological analyses and deep/surface ground displacement monitoring via geotechnical and A-DInSAR data, allows the a posteriori integration of the results by exploiting their complementarity for landslide characterization. The approach was tested in the urban area of Lungro village (Calabria region, southern Italy), which is characterized by complex geological/geomorphological settings, widespread landslides and peculiar urban fabric. In spite of the different level of information preliminarily available for each landslide as result of the independent use of the three methods, the implementation of the proposed procedure allowed a better understanding and typifying of the geometry and kinematics of 50 landslides. This provided part of the essential background for geotechnical landslide models to be used for slope stability analysis within landslide risk mitigation strategies.     

Challenges at the early stages of the environmental licensing procedure and potential contributions from geomorphology

Defining impact significance is the main technical task that influences decision-making during the Environmental Licensing Procedure(ELP).The ELP begins with screening to determine potentially signif-icant impacts of the proposed project.Scoping then follows to address any interventions deemed worthy of attention in the production of an Environmental Impact Assessment(EIA).This will include consider-ation of relevant landforms and geomorphological processes.However,preliminary assessments of envi-ronmental impacts often lack the scientific robustness to procure substantive and transactive effectiveness.This review presents an examination of the established practices of screening and scoping while highlighting the foremost challenges to improve the technical grounds of the ELP.The analysis of screening and scoping practices stresses the need for novel methods that ensure the sequential reasoning between their criteria while improving the preliminary evaluation of impact significance.Reducing the inherent subjectivity of discretionary judgment requires scientific methodologies that acknowledge the interaction between the natural system and human interventions,which has been addressed by geomor-phological research.The knowledge consolidated in this review opens the gate to explore the compatibil-ity between the United Nations strategy of Ecosystem Approach(EA)with the ELP through a novel geomorphological interpretation of the EIA.Therefore,this diagnosis demonstrate that screening and scoping practices would benefit from reliable methods that balance the precautionary principle with the efficient character required in the ELP.     

Surveying the Townscape of Roman Ammaia in Portugal: An Integrated Geoarchaeological Investigation of the Forum Area

Geoarchaeological research, integrating traditional excavations, and ground truthing with intensive geophysical surveys, aerial photography, and GIS‐based data processing, has revealed the full intramural plan of the abandoned Roman city of Ammaia in central Portugal. Although this multidisciplinary effort also focussed on understanding the town/territory relationships and the system of resource exploitation, this paper presents the most important results from fieldwork in the central monumental area of the town, the Roman Forum. Here, excavations, geomorphological survey, and an array of geophysical methods illuminate the long history of the site, from the first settlement and monument‐building phases in early Imperial times, to the ongoing post‐abandonment processes. This paper discusses some of the benefits of compiling these complementary data sets and proposes the use of a wide array of approaches in order to achieve full understanding of the complex topography and evolution of a classical urban site. It further demonstrates the need for effective stratigraphical control and geomorphological analysis of crucial areas revealed by high‐quality geophysics.     

Comparison of geostatistical approaches dealing with the distribution of snow

This paper deals with a stochastic simulation. Snow cover, representing a regionalized variable, was studied and used as an input parameter for a stochastic simulation. The first step included basic statistical analysis of individual parameters of snow, e.g. snow height. In the next step, an analysis of relationships between the snow and the geomorphological parameters (altitude, slope and aspect) was conducted. The most current methods of spatial interpolation and multifactor evaluation are based on weighted regression relationships. Primarily, the use of conditional stochastic simulation was tested in a variety of software. The main aim of this investigation is to compare selected interpolation methods with stochastic simulation, based on the development of the values and on the evaluation of the incidence of extreme events. The study shall provide users with recommendations for selecting the optimal interpolation method and its application to real data.     

A methodology using GIS, aerial photos and remote sensing for loss estimation and flood vulnerability analysis in the Supersano-Ruffano-Nociglia Graben, southern Italy

The impact of calamitous meteoric events and their interaction with the geological and geomorphological environment represent a current problem of the Supersano-Ruffano-Nociglia Graben in southern Italy. Indeed, severe floods take place on a frequent basis not only in autumn and winter, but in summer also. These calamities are not only triggered by exceptional events, but are also amplified by peculiar geological and morpho-structural characteristics of the Graben. Flooding often affects vast agricultural areas and consequently, water-scooping machines cannot remove the rainwater. These events cause warnings and emergency states, involving people as well as socio–economic goods. This study represents an application of a vanguard technique for loss estimation and flood vulnerability analysis, integrating a geographic information system (GIS) with aerial photos and remote sensing methods. The analysis results clearly show that the Graben area is potentially at greatest flood vulnerability, while along the Horsts the flood vulnerability is lower.     

Applied geomorphology and the impact of natural hazards on the built environment

This paper examines the scope and limitations of geomorphological investigation of the sites of architectural and engineering works. Various degrees of vulnerability, forms of impact, and types of applied geomorphological response are summarized. Aspects of land development and construction practice that may increase the vulnerability of buildings and structures to geomorphological hazards are discussed. Strengths and weaknesses of the geomorphological input to hazard mitigation are reviewed. Examples are described that show both negative and positive influences exerted by geomorphological site analysis on urban and regional planning for unstable terrains in Italy. It is concluded that societal choice, within the overall matrix of a society's culture (sensu largo), will influence the way in which vulnerability is managed at sites, and hence the scope for utilizing geomorphological analysis of the physical risks.     

Using Geomorphological Indicators to Predict Earthquake Magnitude (MOb‒Max): A Case Study from Cao Bang Province and Adjasent Areas (Vietnam)

Geotectonics - This paper presents analysis of geomorphological indices for predicting the maximum observed earthquake (MOb?Max) in research region, conducted in three steps: (i)...     

西秦岭新生代以来地质构造过程对青藏高原隆升和变形的约束

西秦岭位于青藏高原东北缘重力梯度带内,是高原物质向北、向东扩展的前缘,其新生代以来地质构造 地貌过程应该是印度板块-欧亚板块的碰撞造山过程和高原隆升过程的一部分。通过对西秦岭内部中-新生代沉积、变形及地貌记录的初步综合分析,得出如下初步认识:(1)根据西秦岭中-新生代红层沉积岩石组合和构造变形特征,可以分为晚侏罗世-早白垩世、晚白垩世-古近纪和新近纪三个构造层,分别对应于西秦岭新生代3个构造演化阶段。(2)西秦岭晚白垩世-古近纪构造层的褶皱缩短和区域断裂带的逆冲推覆发生在古近纪末期-新近纪初期,与整个青藏高原主要逆冲推覆构造事件同步,说明印度板块与欧亚板块碰撞的构造应力在古近纪末已波及至西秦岭。(3)西秦岭新近纪以来经历了一个构造相对稳定的侵蚀夷平期,于36 Ma之前形成了以晚白垩世-古近纪构造层侵蚀面、前新生代碳酸盐地层的岩溶夷平面为标志的主夷平面以及夷平面发育过程中形成新近纪近水平的、以红色粘土岩为主要特征的细碎屑沉积。这一夷平面可以作为高原组成部分的西秦岭隆升的基准面。该夷平面现今高程自西向东逐渐降低,反映了西秦岭隆升呈现自西向东连续的扩展。(4)青藏高原南部构造变形方式在中新世发生了由逆冲推覆 褶皱缩短向伸展走滑的构造转换,而在西秦岭内部却并未发生这样的构造转换,仍然以逆冲构造为主,只是西秦岭北缘的边界断层在中-晚更新世才发生逆冲 左旋走滑作用,这可能指示了青藏高原东北缘晚新生代构造变形的走滑作用只是构造块体边界与构造挤压应力方向下非正交的应力分解所致,同时也可能反映了作为西秦岭块体整体滑移和块体内部的收缩变形并行不悖。(5)由GPS观测数据确定的区域位移场应该指示了现今西秦岭块体的整体缓慢的向东移动,地震机制解确定的构造应力是下地壳向东蠕动拖曳脆性上地壳的整体运动,西秦岭地壳厚度由西向东逐渐增厚是西部由于南北向缩短增厚的下地壳向东扩展流动的结果,增厚地壳的均衡抬升是西秦岭地貌面高度变化的内在原因。     

宇生核素深度剖面暴露测年的原理与应用

宇生核素暴露测年技术是目前第四纪地貌年代测定最常用的方法之一,由于难以定量化继承性核素以及侵蚀对样品暴露年代的影响（通常假设继承性和侵蚀的影响为0）,其测年结果难以反映地貌的真实暴露年代。通过测定地貌剖面不同深度样品的宇生核素浓度,建立"宇生核素浓度-深度"剖面曲线,可同时定量化研究地貌体的暴露年龄、继承性宇生核素浓度以及侵蚀速率,有效地弥补了宇生核素暴露测年中继承性核素以及侵蚀速率不确定性的缺陷。基于蒙特卡洛方法的宇生核素深度剖面暴露测年模型（简称蒙特卡洛深度剖面模型）是最常用的计算模式之一,然而,国内关于该方法的原理及其应用研究相对较少,大大限制了该方法的广泛使用。本文详细阐述了蒙特卡洛深度剖面模型的原理及其在冰川地貌、河流阶地、冲洪积扇等地貌测年中的应用。此外,介绍了深度剖面模型的复现、非稳态模型、线性反演模型等其他几种计算模式并进一步探讨了蒙特卡洛深度剖面模型暴露测年技术的野外采样方法,以使其能够广泛应用于第四纪地貌学和年代学研究中。     

宇生核素深度剖面暴露测年的原理与应用

宇生核素暴露测年技术是目前第四纪地貌年代测定最常用的方法之一,由于难以定量化继承性核素以及侵蚀对样品暴露年代的影响(通常假设继承性和侵蚀的影响为0),其测年结果难以反映地貌的真实暴露年代。通过测定地貌剖面不同深度样品的宇生核素浓度,建立“宇生核素浓度—深度”剖面曲线,可同时定量化研究地貌体的暴露年龄、继承性宇生核素浓度以及侵蚀速率,有效地弥补了宇生核素暴露测年中继承性核素以及侵蚀速率不确定性的缺陷。基于蒙特卡洛方法的宇生核素深度剖面暴露测年模型(简称蒙特卡洛深度剖面模型)是最常用的计算模式之一,然而,国内关于该方法的原理及其应用研究相对较少,大大限制了该方法的广泛使用。笔者等详细阐述了蒙特卡洛深度剖面模型的原理及其在冰川地貌、河流阶地、冲洪积扇等地貌测年中的应用。此外,介绍了深度剖面模型的复现、非稳态模型、线性反演模型等其他几种计算模式并进一步探讨了蒙特卡洛深度剖面模型暴露测年技术的野外采样方法,以使其能够广泛应用于第四纪地貌学和年代学研究中。     

滑带土强度特性研究现状

滑带土强度特性对滑坡稳定性研究和滑坡防治工程设计具有重要意义。通过回顾国内外一些代表性工作,总结了其主要研究内容、研究方法和成果。研究内容包括5种特征强度：峰值抗剪强度、残余抗剪强度、完全软化强度、滑坡启动强度、长期抗剪强度以及相应的微观结构特征;研究方法以现场与室内试验为主,理论分析和反演分析为辅;研究成果主要反映在各种特征强度及其相互关系、剪切引起的微观结构变化特征方面。重点介绍了残余强度研究成果,包括其影响因素和数值估算。最后指出了研究工作中应该加强的几个方面,如特殊滑带土的研究（如砾质滑带土）、新的测试技术和研究方法的发展以及反分析法的正确运用等。     

溃坝风险后果研究现状与发展趋势

溃坝风险后果分析是水库大坝风险评估的重要内容。影响溃坝风险后果的因素多,作用机理复杂,导致不同研究方法的分析结果与实际后果之间均存在较大差异。从风险后果的内涵出发,建议风险后果可分为生命损失、经济损失和环境影响3个基础类别;分析国外研究成果与应用情况,明确从基于历史资料构建经验模型到基于致灾机理构建物理模型的发展趋势;分析中国溃坝风险后果评估现状,明确结合致灾机理的经验模型分析、半定量评价和区域损失叠加计算三类研究方法在准确性和实用性方面的优点与不足;提出应从加强致灾机理分析、注重准确性与实用性的结合、重视非工程措施的重要作用和在应用中不断改进等4个方面采取措施,提高风险后果研究水平和实际应用效果。     

基于低空遥感地貌观测的逆断层陡坎研究:以张流沟滩断层陡坎为例

活动断层相关地貌特征的定量研究是揭示古地震和断裂属性的重要依据,其中陡坎地貌是断裂活动的重要地貌响应,是有效识别活动断裂的重要地貌标志。近年来,无人机低空遥感观测技术的不断进步,使得高分辨率地貌数据的快速获取成为现实。本研究利用无人机低空遥感地貌观测技术,对张流沟滩处的断层陡坎附近进行高分辨率数字地形数据的采集。断层陡坎位于张流沟滩河流Ⅱ级阶地上,影像采集范围为800 m×400 m的矩形区域。经过一系列的影像处理,最终获取了目标区地面分辨率为0.1 m的DEM(数字高程模型)数据。基于该DEM数据可以提取到正交于断层陡坎的高程、坡度剖面。利用高程剖面所展示的地形地貌信息,可以提取到陡坎高度为(2.81±0.05) m;利用坡度剖面所展示的坡度曲线特征,可以推断该陡坎至少经历过两次断错活动事件,并且陡坎存在向上“凸起样式”。通过探槽解译,确定该陡坎下伏断裂至少发生过两次活动事件,其中较早的地震事件接近(3.68±0.14) ka B.P.,最晚期的地震活动应为1927年古浪8级地震,两次断裂活动累计垂直位移为(2.80±0.2) m。将以上两种研究方法相比较可以发现,探槽结构分析与低空遥感获取的定量化地貌信息分析结果基本一致,均能够有效揭示古地震期次及累计的同震位移量。最终本研究将探槽揭示的地层单元的沉积、构造信息与陡坎坡度数据特征相结合,提出了基于断层传播褶皱模型的“陡坎凸起”地貌响应样式来解释陡坎存在的向上“凸起样式”。实践证明,利用无人机低空遥感地貌观测技术能够定量、半定量化揭示下伏断裂的活动信息,结合传统断裂研究手段,可以更全面解释活动断层的沉积、构造特征及地形、地貌现象。总的来说,无人机低空遥感地貌观测技术的应用可作为传统古地震研究的辅助手段,并有其独特的方法优势。