基于RILBP的地形结构尺度稳定特征分析

地形结构描述着地表起伏的形态结构,而高低起伏的地形结构又组成了丰富多样的地貌景观。地表形态一般呈现出局部形态相似与区域有序分异的尺度特征。现有的地形尺度研究不能有效地刻画地形结构的尺度特征,地貌形态的适宜表达尺度及地形结构的尺度稳定特征仍值得进一步探讨。该文以黄土高原不同地貌类型区为例,以数字高程模型(DEM)为数据源,从刻画地表形态的局部特征入手,系统地选取了多类具有代表性的地貌形态样本数据,分析了典型地貌类型区域的局部二值模式(LBP)分布特征。考虑到地形结构与RILBP之间一对多的对应关系,利用顾及旋转不变特性的LBP(RILBP)算法探究地形结构的尺度稳定特性,发现随着分析窗口增大,LBP显示出逐渐趋于稳定的尺度特征。研究结果表明,RILBP能够有效地表达地形结构,地形结构稳定单元能够有效地反映适宜的地形分析尺度,地形结构对地形多尺度信息的挖掘具有独特的优势。     

基于多尺度DTM的坡式梯田三维可视化研究

针对黄土高原梯田可视化问题,以往的相关研究基本解决了水平梯田的三维可视化,但关于坡式梯田的研究尚为空白。坡式梯田因其具备更加突出的人工微地形特性,难以通过传统的DEM可视化方法实现其三维可视化。该文提出了多尺度DTM叠加法,利用偏移线法、高程增量法等方法提取田埂坡度特征,将研究区的低分辨率格网DEM(G-DEM)、坡式梯田分布区的高分辨率坡度DTM及G-DEM融合为一体,对坡式梯田进行三维叠加可视化。与传统G-DEM可视化方法相比,多尺度DTM叠加可视化法不仅所需数据存储量更小,而且具备更加逼真的坡式梯田三维可视化效果,能够有效显示坡式梯田的平坦田面和陡直田埂,是对基于DEM的梯田地形三维可视化的有益探索。     

一种基于改进双树复小波变换的地形纹理特征提取方法

地形纹理特征提取和识别是地形自动分类的关键。该文在分析已有地形纹理特征提取方法的基础上,提出一种基于双树复小波变换的地形纹理特征提取和识别方法。该方法将DEM地形垂直特征信息引入双树复小波变换模型,设计并实现了面向DEM地形数据特点的地形纹理特征提取方法。以陕北黄土丘陵沟壑区为实验样区,选取6个不同地貌特征共109个典型地形纹理样本进行特征识别实验,并将实验结果与常用的灰度共生矩阵(GLCM)模型及Gabor滤波结合PCA方法进行对比。研究显示,基于地形垂直特征改进的双树复小波变换模型对6类样本有较高的识别精度,同时消耗最短的纹理特征构建时间。     

DEM数据可视化在地震应急中的应用

数字高程模型(Digital Elevation Model简称DEM)是通过一组有序数值阵列对地面海拔高度数字描述的实体地面模型,是数字地形模型(Digital Terrain Model,简称DTM)的一个子集。并可通过对DTM数字处理得到其他各种地形特征值。DTM是描述包括高程在内的各种地貌因子,如坡度、坡向、坡度变化率等因子在内的线性和非线性组合的空间分布,其中DEM是单一的数字地貌模型,通过对DEM数据处理可派生出坡度、坡向及坡度变化率等地貌特性。基于ARCGIS技术平台,对DEM数据进行处理建模,可以得到地形真实情景再现,为震后应急指挥人员、工作人员了解震区的地貌、地形提供直接的数据支撑。     

基于DEM的湖南省地貌形态特征分类

针对当前地貌分类较少关注微观地貌特征信息的问题,该文依据1∶25万DEM数据开展湖南省地貌形态特征分类的实验研究。首先,确定分类实验的最佳分析窗口为0.28km~2。其次,根据可以反映宏观形态特征的起伏度和切割度指数,可以反映微观形态特征的地形位置指数(TPI),构建了分类指标体系并将湖南省按照地貌形态特征分为12种地貌类型。第三,地貌分形维数值是检验地貌形态特征的重要指标,选用研究区5个小流域并分别计算其分维数值,据此进行分类结果检验。研究结果说明该文的实验方法可以较好地体现微观地貌形态信息。     

响应区域自然特征的巴渝梯田人居景观图式研究

以巴渝地区形态结构完整且具有代表性的梯田区域遥感图像为研究对象,结合史料分析和田野调查,采用可视化的景观图式语言,对单一的梯田水利技术及其时空组合模式以及梯田人居环境3方面的营建特征进行分析,构建巴渝梯田人居系统的景观图式体系。研究发现：1）响应巴渝山地地貌及“春旱夏涝”降雨特征,形成秋水春用的冬水田、夏季排洪的冲冲田以及四季关水的囤水田等系列在地性梯田水利技术;2）巴渝梯田水利技术在时间上形成适应春旱夏涝的“秋蓄-冬沃-春耕-夏排”水资源管理模式,在空间上形成顺应地貌的“高囤-低灌”组合模式;3）梯田人居环境响应地貌影响下水安全差异性,呈现交叉汇聚梯田基底与涵养林为基底嵌套咬合散点型民居斑块的“有机分散型”低山丘陵区梯田人居模式,和涵养林为基底边缘渗透单向跌落梯田与集中型聚落斑块的“大面集中型”中高山沟谷区梯田人居模式。综上,巴渝梯田水利技术类型、组合方式以及梯田人居在山地地貌的建构模式是契合巴渝特有地理地貌和水文条件的经验集成,对城乡低影响开发建设以及传统营建智慧的保护具有积极借鉴意义。     

基于高分辨率DEM的黄土地貌正负地形自动分割技术研究

黄土地貌正负地形自动分割是构建地表空间分布式机理-过程模型的基础。在分析黄土高原地区典型地貌坡面形态及汇流过程特征的基础上,提出了基于5m分辨率栅格DEM自动分割黄土正、负地形的技术方案。该方案首先利用坡面上下游栅格点的坡度对比识别沟沿线点,然后利用汇水模型提取沟沿线点约束的上游汇水区域,从而实现正、负地形的自动分割。在黄土塬区及丘陵沟壑区的实验结果表明,该方法的优点是提取精度高,人工干预少,在不同地貌类型区域内有很好的应用适宜性。     

南京师范大学数字地形分析研究团队介绍

正南京师范大学数字地形分析研究团队,在汤国安、刘学军教授领导下,多年来一直从事数字高程模型(DEM)及基于DEM的数字地形分析科学研究与教学工作。近年来,主持了包括国家863重点课题及国家自然科学基金重点项目在内的20多项国家级科学研究项目。在DEM尺度效应与不确定性、高保真DEM构建、数字地形分析并行技术与中间件等方面的理论与方法研究中取得突破性进展,获得国家测绘地理信息局、中国地理信息产业协会颁发的地理信息科技进步奖一等奖、二等奖;该团队基于DEM数据对黄土高原地貌形态空间格局展开了深入研究,提出了坡谱分析法、地形特征点簇分析法、地形纹理分析     

面向DEM地形复杂度分析的分形方法研究

在基于栅格DEM数据的基础上,应用分形几何学方法,采用元分维模型理论,提出一种描述DEM地形复杂度的分形分析方法,并得出分析指标———地形分维指数(TFI)。实验证明,该指标可以有效描述栅格DEM数据反映的地形变化特征,分析窗口由小到大的规律性变化反映出地貌从微观到宏观的变化情况,因此其既可以作为对栅格DEM所描述地形进行评价的坡面因子,又可以作为基于DEM的地貌类型区自动划分的参照依据。     

DEM 点位地形信息量化模型研究

针对DEM 点位, 首先应用微分几何法对其所负载的语法信息量进行测度, 其次根据地形特征点类型及地形结构特征确定其语义信息量, 然后基于信息学理论构建了DEM 点位地形信息综合量化模型。在此基础上, 以黄土丘陵沟壑区作为实验样区, 对DEM 点位地形信息量提取方法及其在地形简化中的初步实例应用进行了探讨和验证。实验结果显示, 所提出的DEM 点位地形信息量化方案可行;基于DEM 地形信息量指数的多尺度DEM 构建方案, 具有机理明确、易于实现的特点, 并通过优先保留地形骨架特征点, 可以有效减少地形失真, 从而满足不同层次的多尺度数字地形建模和表达要求。对DEM 点位地形信息进行有效量化, 为认识DEM 地形信息特征提供了一个新的切入点, 同时为多尺度数字地形建模提供理论依据与方法支持。     

大连半岛地貌,新构造运动与市区安全性

辽东半岛南端的大连半岛是一个刚性断块。其上无活动性大断裂穿过,老断裂多而规模小,在地貌和新地层上无新活动表现。穿越它们的第四纪河、海阶地均平行分布,无明显的垂直或水平错位。整个半岛第四纪以来作整体断块上升。半岛上的小震稀少零星,属刚性断块地壳应力作用下的微破坏活动。位于其上的大连市是安全的,无发生破坏性大震的危险。     

河西走廊平原区全新世河流阶地对气候变化的响应

河西走廓的古洋河，黑河，北大河和疏勒不可在平原发育了两级阶地，根据＾１４Ｃ测年数据，低阶地形成于５．５７－３．１５ｋａＢ．Ｐ．，高阶地形成于１１－８ｋｇＢ．Ｐ．，在８－６ｋａＢ．Ｐ．之间为河流下切期。     

祁连山东段河流阶地的形成时代与机制探讨

第四纪期间祁连山东段发育了多级洪积台地与河流阶地,它们是研究区域构造活动与气候变化良好的载体。对该区主要河流阶地序列的野外考察,利用ESR、TL、IRSL以及¹⁴C等测年方法,研究表明,第四纪期间石羊河上游的各大支流普遍发育了5-6级阶地,其中南营村附近金塔河五级河流阶地的形成时代大致为1.24MaB.P.(T₅)、0.78MaB.P.(T₄)、0.14MaB.P.(T₃)、0.06MaB.P.(T₂)和0.01MaB.P.(T₁),完全可以与该区沙沟河、黄河兰州段以及长江三峡段的阶地序列相对比。从各级阶地砾石层的堆积时代以及阶地的沉积特征分析,我们认为,即使在构造活动区域,气候变化在河流地貌演化过程之中起着重要的控制作用。     

Post-glacial fluvial response and landform development in the upper Muskegon River valley in North-Central Lower Michigan, U.S.A.

This study focuses on the upper part of the Muskegon River system in north-central Lower Michigan and is the first to reconstruct the post-glacial history of fluvial landform development in the core of North America's Great Lakes region. Results indicate that the upper Muskegon River valley contains four alluvial terraces and numerous paleomeanders. Radiocarbon dating of peats within these old channels provides a good chronology for stream behavior and landform development. The T-4 terrace is a paired Pleistocene outwash/lacustrine surface that probably formed about 12,500 years ago. The T-3 terrace is a fill-strath surface that was cut between about 12,000 and perhaps 9500 years ago. The geometry of macromeanders on this surface suggests that stream discharge was  8 times greater than during the Holocene.The Pleistocene/Holocene transition is marked by a major period of downcutting that likely began as the climate warmed/dried and sediment yield diminished. This period of downcutting potentially lasted through the drier middle Holocene, creating a 6-m-high escarpment in the valley. The Muskegon River then began to aggrade when the climate became wetter. Subsequently the river again incised, creating the paired T-2 terrace, about 3400 years ago when the climate became still wetter. T-2 paleomeanders indicate that stream discharge at this time was consistent with the modern river. In the past 2500 years, the stream has constructed a poorly defined complex of T-1 terraces. These surfaces likely formed due to complex response associated with more variable climate. This study demonstrates that the upper Muskegon River has a similar post-glacial history as streams on deglacial and periglacial landscapes elsewhere in the world.     

New constraints on the late Cenozoic incision history of the New River, Virginia

The New River crosses three physiogeologic provinces of the ancient, tectonically quiescent Appalachian orogen and is ideally situated to record variability in fluvial erosion rates over the late Cenozoic. Active erosion features on resistant bedrock that floors the river at prominent knickpoints demonstrate that the river is currently incising toward base level. However, thick sequences of alluvial fill and fluvial terraces cut into this fill record an incision history for the river that includes several periods of stalled downcutting and aggradation. We used cosmogenic ¹⁰Be exposure dating, aided by mapping and sedimentological examination of terrace deposits, to constrain the timing of events in this history. ¹⁰Be concentration depth profiles were used to help account for variables such as cosmogenic inheritance and terrace bioturbation. Fill-cut and strath terraces at elevations 10, 20, and 50 m above the modern river yield model cosmogenic exposure ages of 130, 600, and 600–950 ka, respectively, but uncertainties on these ages are not well constrained. These results provide the first direct constraint on the history of alluvial aggradation and incision events recorded by New River terrace deposits. The exposure ages yield a long-term average incision rate of 43 m/my, which is comparable to rates measured elsewhere in the Appalachians. During specific intervals over the last 1 Ma, however, the New River's incision rate reached 100 m/my. Modern erosion rates on bedrock at a prominent knickpoint are between 28 and 87 m/my, in good agreement with rates calculated between terrace abandonment events and significantly faster than 2 m/my rates of surface erosion from ancient terrace remnants. Fluctuations between aggradation and rapid incision operate on timescales of 10⁴− 10⁵ year, similar to those of late Cenozoic climate variations, though uncertainties in model ages preclude direct correlation of these fluctuations to specific climate change events. These second-order fluctuations appear within a longer-term signal of dominant aggradation (until 2 Ma) followed by dominant incision. A similar signal is observed on other Appalachian rivers and may be the result of sediment supply fluctuations driven by the increased frequency of climate changes in the late Cenozoic.     

Crustal uplift in southern England: evidence from the river terrace records

Much of the past work on the Quaternary rivers of northwest Europe has been concerned with river terraces, which characterise almost every valley. While these terraces are undoubtedly striking features of the landscape, the incision achieved by Quaternary rivers is equally significant in terms of river behaviour, and for an understanding of the factors affecting landform development during the Quaternary. This paper examines the incision achieved during the Quaternary by the Thames, in both its upper and lower catchments, and by the Hampshire Avon in southern England. Valley incision rates of ca. 0.07–0.10 m ka⁻¹ have been identified, although in the lower catchment of the Thames, these have been enhanced by additional incision in response to glacio-isostasy and valley shortening. A model is proposed in which regional uplift is recognized as the primary cause of incision by these Quaternary rivers. Possible mechanisms for regional uplift are considered.     

鄂尔多斯高原周缘黄河阶地的形成与青藏高原隆升

构造运动和和气候变化是河流阶地形成的两个重要因素。学术界对于构造运动与气候变化中哪个因素是河流阶地形成的控制因素尚未形成一致观点。本文选择位于鄂尔多斯高原周缘的河流阶地,综述了前人在兰州段、中卫段和晋陕峡谷段3个河段的黄河阶地上的研究成果,结合2万年以来的古洪水记录与古地震活动等证据,对比了河流阶地形成、气候变化以及青藏高原的幕式隆升的时间。对比结果显示,鄂尔多斯高原周缘多级河流阶地的形成时间与青藏高原阶段性隆升的时间比较一致,而与气候冰期—间冰期变化之间没有明显规律,这一结果支持构造运动是鄂尔多斯高原周缘的河流阶地形成的控制因素。     

淡水河口海岸阶地之对比

海阶是海平面变动、地壳变动或两者共同作用之结果．海阶研究不仅可据以推论古气候、往昔海平面变化及地壳变动状况,更可藉以了解各区域间变动的差异,对全盘了解大地构造具有基本的重要性．本文研究区位于欧亚大陆板块与菲律宾海板块的碰撞地带,地壳活动频繁,海阶的分布、规模等,除了受到海平面变动影响之外,尚受到区域性地壳隆升以及近期火山活动的影响．研究结果显示,淡水河两岸的海阶阶序,分别为北岸9阶,由低至高为第Ⅰ阶0～10m、第Ⅱ阶30～50m、第Ⅲ阶55～95m、第Ⅳ阶100～130m、第V阶135～173m、第Ⅵ阶190～275m、第Ⅶ阶285～310m、第Ⅷ阶320～365m、第Ⅸ阶375～405m．南岸有7阶,第Ⅰ阶0～10m、第Ⅱ阶25～50m、第Ⅲ阶65～95m、第Ⅳ阶115～138m、第V阶150～200m、第Ⅵ阶230～275m、第Ⅶ阶285～350m．利用海阶对比基图,得到各段阶地生成年代分别为北岸6kaBP（Ⅰ）、40kaBP（Ⅱ）、57kaBP（Ⅲ）、77．5kaBP（Ⅳ）、88．5kaBP（Ⅴ）、126．5kaBP（Ⅵ）、148．5kaBP（Ⅶ）、183kaBP（Ⅷ）、202kaBP（Ⅸ）．淡水河口南岸分别为6kaBP（Ⅰ）、40kaBP（Ⅱ）、57kaBP（Ⅲ）、79kaBP（Ⅳ）、100kaBP（Ⅴ）、126．5kaBP（Ⅵ）、173．4kaBP（Ⅶ）．淡水河两岸仅一水之隔,区域性地壳变动及海平面变动大致相同,但大屯火山之活动年代较观音火山之年代早,因而大屯山地势较高,经过比对,隆升速率影响地势高低与海阶发育特征,两岸之平均隆升速率分别是北岸的2．2mm／a和南岸的2．15mm/a,北岸略较南岸活跃,阶数多,地势高．     

台湾西北部海岸阶地的研究

海岸阶地的形成通常是海准面变动、地壳变动或两者共同作用之结果．研究海阶不仅可印证推论古气候、往昔海准面变化及地壳变动状况,更可藉以了解各区域间变动的差异,全盘了解大地构造的意义,而且小规模的海阶变动,时常与地震活动伴生,因此,研究海阶更可作为判读地震周期的依据之一,所以,世界各地位于地壳活动带的国家对于海阶的型态与演育过程均作详细的调查及研究．本研究以淡水河以南至大安溪以北之海阶作为研究范围,发现台湾西北部位于观音山北部沿海、新竹山子顶沿海、客雅溪口南岸、后龙溪口南岸等4个地区,都有零星的海阶分布．经过阶地分布、地形特征与阶序对比,并利用世界海阶对比基图求出该地区的地壳隆升率与海阶可能形成的年代,藉以了解各区域间变动的差异．台湾西北部海岸地区的海阶大致上可划分为高位及低位2群阶：也,高位海阶分布的高度在15～275m之间,阶面覆盖着红壤层,为晚更新世时所造成;低位海阶分布的范围与高度较小,在海滩与高位阶地末端阶崖之间,沿着海岸成带状分布,阶面无红壤掩覆,海拔大多在10m以下．低位海阶构成的物质多以砾石及砂为主,属全新世海阶,即第四纪最后一次冰期结束后,近1万年以来全球高海水位时期所形成．利用海阶对比基图与已有的定年数据,辅以地形地貌及堆积物特征比较,获得各段阶地之平均隆升率,观音山北部沿海、客雅溪口南岸、后龙溪口南岸3个地区,经过比对,分别是2．1mm／a、2．2mm／a、2．15mm／a,数值相近,显示该区之地盘隆升率及海准面变动状况大致相同;仅新竹山子顶沿海地盘隆升率较小,为1．4mm／a．此表示,台湾岛的海阶变化不仅受到海准面变动的影响,尚受到区域性地壳隆升的控制．     

Transportation Accessibility of Central Towns in Important Agricultural Heritage Systems Sites in Mountainous Areas and Its Impact on Local Economic Development: A Case Study of Honghe Hani Rice Terraced System,Yunnan

Transportation as a means to support industrial development can impact the economic development of important agricultural heritage sites. Because the central towns in mountainous areas have weak economic interactions with each other, an appropriate method is needed to evaluate their transportation accessibility. This paper takes the Honghe Hani Rice Terraced System (HHRTS) as a study area and develops a model to determine shortest time-distances from central towns in the study area to the nearest high-grade city as a way to evaluate transportation accessibility (TA). We then analyze the relationship between the accessibility of these towns and their economies. The study finds that the TA of the central towns in HHRTS is not good as a whole. More than 70% of the towns are more than 1 hour away from their nearest high-grade city. Of the four counties in the study area, Yuanyang County has the best traffic conditions, while Lvchun County has the worst traffic conditions. The central towns in the northern and middle regions have better TA than those in the west, southwest and east margin regions. The small-scale rural economy has little dependence on the transportation network, while secondary industries are obviously impacted by the transportation network. In the future, to support the integrated development of industries in HHRTS, traffic conditions in each town should be improved appropriately according to the industrial orientation of the town, but excessive investments to construct roads irrespective of eco-environmental impacts and economic benefits should be avoided. Especially in the case of ecologically vulnerable towns, the building high-grade roads should be banned.