Scaling in river corridor widths depicts organization in valley morphology

Landscapes have been shown to exhibit numerous scaling laws from Horton's laws to more sophisticated scaling in topography heights, river network topology and power laws in several geomorphic attributes. In this paper, we propose a different way of examining landscape organization by introducing the “river corridor width” (lateral distance from the centerline of the river to the left and right valley walls at a fixed height above the water surface) as one moves downstream. We establish that the river corridor width series, extracted from 1 m LIDAR topography of a mountainous river, exhibit a rich multiscale statistical structure (anomalous scaling) which varies distinctly across physical boundaries, e.g., bedrock versus alluvial valleys. We postulate that such an analysis, in conjunction with field observations and physical modeling, has the potential to quantitatively relate mechanistic laws of valley formation to the statistical signature that underlying processes leave on the landscape. Such relations can be useful in guiding field work (by identifying physically distinct regimes from statistically distinct regimes) and advancing process understanding and hypothesis testing.     

Structure of river valleys on the Lena-Katanga Plateau

Exploration data for different-order river crossings on the Lena-Katanga Plateau (northern Irkutsk oblast) were used to identify, according to the occurrence conditions of bedrocks, weathering crusts and alluvial deposits, three types of structure of river valley bottoms. In the geological evolution history of loose deposits in the valleys, six stages were determined, which occurred mostly during the Holocene. Karst lakes evolved into existence along tectonic fault lines in the river valleys at that time period which complicated their structure.     

Fluvial diversity in relation to valley setting in the source region of the Yangtze and Yellow Rivers

The spatial distribution of valley setting （laterally-unconfined, partly-confined, or confined） and fluvial morphology in the source region of the Yangtze and Yellow Rivers is contrasted and analyzed. The source region of the Yangtze River is divided into 3 broad sections （I, II and III） based on valley setting and channel gradient, with the upstream and downstream sections being characterized by confined （some reaches partly-confined） valleys while the middle section is characterized with wide and shallow, laterally-unconfined valleys. Gorges are prominent in sections I and III, while braided channel patterns dominate section II. By contrast, the source region of the Yellow River is divided into 5 broad sections （sections I-V） based on valley characteristics and channel gradient. Sections I, II and IV are alluvial reaches with mainly laterally-unconfined （some short reaches partly-confined） valleys. Sections III and V are mainly confined or partly-confined. Greater morphological diversity is evident in the source region of the Yellow River relative to the upper Yangtze River. This includes braided, anabranching, anastomosing, meandering and straight alluvial patterns, with gorges in confined reaches. The macro-relief （elevation, gradient, aspect, valley alignment and confinement） of the region, linked directly to tectonic movement of the Qinghai-Tibet Plateau, tied to climatic, hydrologic and biotic considerations, are primary controls upon the patterns of river diversity in the region.     

塔里木河下游生态输水河道两侧区域地下水运动规律研究

根据塔里木河下游断流区域含水层水文地质特征及其实际输水过程中河水对浅层地下水的补给规律,建立了塔里木河下游绿色走廊生态输水河道附近区域地下水运动的一维非稳定流模型,并通过在整个输水过程中流量与水位两种边界条件相互转换的一种方法求解模型。最后应用上述模型分析了间歇性输水条件下塔里本河下游断流河段河道两侧地下水位恢复状况,为输水生态效益的定量评价及其今后输水工作的决策提供理论基础。     

DRAINAGE REVERSALS AND TRANSVERSE RELATIONSHIPS OF RIVERS TO MORAINES IN SOUTHERN MICHIGAN

In southern Michigan, a multiglaciated area of thick drift, regional differences in the altitude of the buried bedrock surface control the direction of major drainage lines and facilitated some stream reversals during deglaciation. Furthermore, individual bedrock valleys, though deeply buried, may influence surface forms in a fashion that induces transverse relationships between river courses and morainal trends. Apparently one or more ancestral glacial landscapes were influenced by the bedrock surface and are also reflected in the present topography. Such palimpsest landscapes may be more widespread in glaciated terrains than have generally been recognized.     

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.     

Coupling relationships: Hillslope–fluvial linkages in the Hodder catchment, NW England

Variations in the coupling of sediment transfer between different parts of a fluvial catchment, e.g., hillslope to axial stream, can hamper understanding but are an integral part of the geomorphological record. Depositional environments respond to a combination of land use, climate, storms (floods), and autogenic conditioning. The distribution of sediment in the upland landscapes of NW England is out of equilibrium with contemporary climate and geomorphological processes; more a function of peri- and paraglacial mobilisation of glacigenic deposits. Soil and vegetation development after deglaciation have interrupted any progression toward sediment exhaustion with sediment release controlled largely by extrinsic perturbation, with late Holocene anthropogenic activity, climate and extreme hydrological events the likely candidates. This paper presents a new radiocarbon-dated Holocene geomorphological succession for the River Hodder (NW England), alongside evaluating new palaeoecological and geoarchaeological data to discern the impacts of human activity. These data show a late Holocene expansion in human occupation and use of the landscape since the Iron Age (700–0 cal. B.C.), with more substantial changes in the character and intensity of upland land use in the last 1300 years. The geomorphological responses in the uplands were the onset of considerable and widespread hillslope erosion (gullying) and associated alluvial fan development. Interpretation of the regional radiocarbon chronology limits gullying to four, more extensive and aggressive phases after 500 cal. B.C. The downstream alluvial system has responded with considerable valley floor deposition and lateral channel migration that augmented sediment supply by remobilising the existing floodplain terraces and led to the aggradation of a series of inset alluvial terraces. The timing of these changes between states of aggradation and incision in alluvial reaches reflects the increased connectivity between the hillslope and alluvial systems. Aspects of both the regional climate and land use histories are conducive to increasing discharge and sediment flux, but the region wide lowering of erosion thresholds appears a key driver conditioning these sediment-rich conditions and producing a landscape that was more susceptible to erosion under lower magnitude flows.     

北京市等时间交通圈的范围、形态与结构特征

不同层次和范围的交通圈是经济社会空间组织的重要依据。本文运用网络分析与成本加权距离集成算法,设计了定量界定交通圈的技术路线。在此基础上,以通勤便捷为目标,提出1小时交通圈内部圈层的划分方法和轨道交通服务指数,据此分析了北京1小时交通圈的内部层次和结构特征;以经济分工协调为目标,基于时空距离与交通方式,划分北京一日交通圈的圈层,并提出交通廊道的界定方法,据此探讨了北京一日交通圈内部各廊道地区的空间范围与经济基础。结果显示：北京市等时间交通圈的形态受高速交通影响较大,具有显著的偏向式延伸特点,并在边缘地带形成少量“岛”;轨道交通对北京市1小时交通圈的支撑力度较弱,未来应加强重点方向的轨道交通建设;根据各廊道的具体情况,京津廊道、京唐廊道是京津冀协同发展的重要载体,京石廊道宜定位为承接北京地区产业转移的重点地区,京承廊道与京张廊道则适宜发展生态型经济。     

近20年来中国古河道研究进展

近20年来,我国在嫩江大安古河道、莱州湾南岸平原古河道、长江南京以下段古河道及古深槽、海底古河道等区域的研究,获得了大量研究成果,深化了理论认识,拓展了应用领域。这些新成果与新认识进一步表明,中国各外流大河均有末次盛冰期埋藏古河道,该期古河流深切于末次冰期间冰阶的陆地及浅海大陆架,形成切割谷和谷底部的深槽,谷内堆积了末次盛冰期和早全新世的河流相滞留物质和粗颗粒物质,上部被中全新世海相、海陆交互相或陆相细粒物质覆盖,构成了埋深约20~50 m的浅埋古河道带。古河道中蕴藏着比较丰富的地下淡水,是洪冲积平原及浅海陆架地区的重要水源。     

长江下游地区过江通道发展利用与“时空压缩”的演变特征

长期以来过江通道供需矛盾突出,高效利用现有通道并合理规划建设新通道设施、吸引两岸要素无障碍流动成为长江下游地区率先实现跨江发展、推进次区域合作的基本物质保障。基于此分析2000年以来长江下游地区公路过江通道建设对南北岸间交通的“时空压缩”效应,尝试探讨高等级公路网体系中过江通道通行利用空间特征。研究时段内过江通道建设实现由点到面扩张,从单一到多样化的跨江条件改善压缩区位差异对发展造成的不公平,跨江时间成本逐渐转变为自岸向两侧的由高到低梯度推移。沿岸地区就近选择过江通道,中远岸市县由高等级公路网引至特定通道方向,完整的过江通道是包含跨江桥隧和后方高等级连接公路的交通走廊。各通道因其在路网体系中的定位不同,通行利用存在差异,区域空间和基础设施建设的有限性要求建立“干线公路-跨江桥隧”多对多选择,提升既有通道通行能力并将连接道路建设向新通道方向倾斜,以分流通行压力并缩小区域内跨江成本差距。     

Spatial correspondence of knickzones and stream confluences along bedrock rivers in Japan: implications for hydraulic formation of knickzones

Knickzones, defined here as locally steep reaches including distinct knickpoints, in bedrock river morphology, have often been investigated in relation to local anomalies in lithology, tectonics, hydraulics, climate and associated base‐level change, and/or deformation of valley‐side slopes. However, exact formative causes of many knickzones in a humid, tectonically active island arc remain unclear. Using databases of geology, streams and knickzones, we examine knickzone distribution across the Japanese Archipelago to evaluate the effects of the stream network structure and rock type boundaries on knickzone formation. Knickzones are frequently found just upstream and downstream of major stream confluences along mainstreams, whereas knickzones are less frequent around major rock type boundaries. While the major confluences do not form hanging valleys due to similar catchment size, this observation suggests that many knickzones have been formed by the long‐term effect of flow turbulence scouring bedrock at the confluences. Such a hydraulic control on bedrock erosion in the steep Japanese mountains under humid climate conditions indicates that the formative cause of many knickzones therein can be autogenic by means of stream hydraulics.     

三江并流区干热河谷成因新探析

干热河谷是青藏高原周边及三江并流区引人注目的、较为独特的地生态现象。干热河谷是构造-地貌-古生态效应、环流-季风-“狭管”效应、地形波-局地环流-降水-焚风效应、植被-土地利用-人类活动干扰效应等综合作用而形成的原生性的地生态现象。早第三纪时,三江并流区是斜贯我国广阔干旱气候带的组成部分。随着青藏高原的隆起和西南季风的形成演化,逐渐向暖湿性的亚热带气候和植被演化,进入上新世末-更新世以后,纵向岭谷地貌形成,大江大河溯源侵蚀,河谷深切,在深切河谷下部逐步形成与其纬度位置相当的干旱半干旱生态景观,从古生态上实现了某种意义上的“返祖”现象。冬半年本区受西风南支急流控制形成干季,夏半年受西南季风控制,尽管带来大量水汽,但受特殊地貌格局影响,在本区形成金沙江河谷等四个少雨区,部分气流沿狭窄平直河谷急速北流一路无阻,水汽被输送到北部地势增高之处形成地形降雨。纵向排列的岭谷地形波,形成明显的降水波状起伏分布曲线,气流越过山岭后下沉气流带来“焚风”效应,形成干热河谷。人类活动叠加在原已生态脆弱的干热河谷生态系统之上,社会经济发展使其土地利用强度加剧、植被减少、水土流失严重等,促使生态环境进一步朝干热化方向发展。因而,干热河谷形成有着其地史、大气环流、季风、大地貌及地形波效应、植被抗逆性差等自然要素的综合作用,并叠加了人类的干扰,是局地地-气-水-生-人交互作用及耦合效应的综合产物。     

Late Devensian and Holocene landscape change in the uplands of the Isle of Man

The Late Glacial and Holocene geomorphology of the Manx uplands has received scant attention in previous researches. Solifluction deposits and terraces provide the earliest evidence for geomorphic activity after deglaciation. Fluvial incision into drift-choked valleys is correlated with the formation of the large mountain front alluvial fans that flank the Manx uplands. Formation of these alluvial fans is constrained to 15,000–10,500 cal. years BP by ¹⁴C dates on organic deposits beneath and above the alluvial fan gravels. Alluvial fan and river terraces along four valleys postdate this incision. Optically Stimulated Luminescence (OSL) and ¹⁴C dating provide a tentative chronology for these landforms. The higher terraces are Late Glacial fluvial surfaces that were probably occupied by rivers into the Holocene. Incision during the Late Holocene led to the abandonment of the higher surfaces, producing a suite of younger river terraces and alluvial fan surfaces. Independent dating constrains this fluvial activity to post-Bronze Age (3500–2800 cal. years BP). Increased human activity and climatic change during the Late Holocene are possible causes for this increased geomorphic activity.     

东北亚区域国际合作中跨境交通走廊的发展及其对环境退化的影响

东北亚区域跨境交通走廊由于图们江地区国际合作开发的深入而得到迅速发展，其对区域环境退化已经形成和将要形成重大的影响。本文在对东北亚区域国际合作中跨境交通走廊的运行及其发展进行深入研究的基础上，对跨境交通走廊的发展对区域环境退化的影响作了战略性的评价与分析，并对其未来发展提出若干建议。     

渭河三阳川盆地最高级阶地的年代厘定及其对河谷发育的指示意义

青藏高原东缘水系的演化历史长期存在着重大争议,鉴于任一水系的形成演化都是通过主要河谷的发育及其不断延展与整合完成的,因此确定河谷发育的起始时代是研究水系演化的关键。本文针对渭河上游三阳川盆地最高级阶地形成时代的研究,发现李家小湾河流阶地砾石层的ESR年代为1.26±0.15 Ma和1.32±0.19 Ma,26Al/10Be埋藏年代为1.45±0.70 Ma和1.04±0.43 Ma,说明该段河谷形成于早更新世晚期。综合青藏高原东缘夷平面、剥蚀面与河流阶地的研究成果,推断该区现代河谷系列主要形成于1.2 Ma以后,河流平均下切速率较高,为0.1~0.32 m/ka,指示了中更新世以来该区快速的地表抬升与河谷发育过程;而其前少数地段的先成河谷下切速率介于0.04~0.29 m/ka之间,说明区域地势总体低平,地表过程以剥蚀夷平为主,即高原东缘的现今水系格局主要是第四纪期间构造和气候共同作用下河流侵蚀的产物。     

福建长乐屏山风化坑与河流壶穴的成因及其证据

风化坑和壶穴是一种常见的岩石坑穴地形,其形成原因和形态完全不同,但容易被误解和混淆.结合对福建长乐三溪河地区这两种坑穴地形的实地考察,本文从地貌学,沉积学,岩石化学和矿物学等各个方面对两者的形成过程、影响因素进行了论证和对比.研究表明：风化坑形成于岩石面积水的风化作用,壶穴则是由河流的旋转水流对河床产生的侵蚀作用形成;山顶风化坑的发育与河流流水作用没有关系,河流壶穴的形成与河谷的发育过程有关,河谷中的风化坑只能在河流深切后,流水不再作用到的河床部位发育;只要条件合适,风化坑或壶穴随时可以生成;风化坑与河流壶穴的形态,坑内沉积物的磨圆度、粒度特征等反映出各自不同的形成过程.风化坑内碎屑与周边岩石的化学蚀变指数CIA 值的差异反映了风化坑的化学风化成因;风化坑内碎屑与周边岩石石英长石比例的差异说明风化坑是矿物差异风化的结果;用CIA 值和英长比均无法区分河流壶穴和风化坑中的碎屑颗粒,但两者化学元素迁移特征的差别反映了风化坑的风化作用和河流壶穴的流水搬运作用的成因差别;风化坑的风化程度达不到当地风化壳的风化程度,但不同气候带风化坑碎屑的CIA 值能反映不同气候带风化作用的强度差异.     

桂林漓江环境保护综合治理开发研究

本文分析桂林漓江综合治理的现状和存在问题，阐明漓江干流枯水成因，指出生态环境遭到破坏已制约漓江流域经济建设的发展并影响桂林漓江的世界声誉。在坚持“保护、治理、开发”三结合的原则下，应大力发展和保护造林绿化工程，兴建漓江补水工程，整治重点污染源工程，开发旅游资源工程和旅游交通设施工程等建设项目，通过采取生态、工程和管理的综合措施，促进该流域的经济社会、生态、环保、旅游等事业协调发展。     

STORAGE OF MINING-RELATED ZINC IN FLOODPLAIN SEDIMENTS,BLUE RIVER,WISCONSIN

This study investigates spatial patterns of sediment-associated zinc (Zn) storage in floodplain deposits and the potential reintroduction of these metal-contaminated sediments to the active channel by bank erosion. We estimate patterns of Zn mass storage by combining longitudinal trends in Zn concentrations with measurements of sediment mass storage in overbank and point-bar deposits. Overbank deposits are the largest contaminant sink, storing five times more Zn than the point-bar deposits. While Zn concentrations decrease downstream because of dilution effects, the total mass of Zn stored in floodplains is greatest in both the upstream reaches and in the wider lower valleys where low channel gradients promote rapid sedimentation. Zn storage is low in middle reaches where steep, narrow valleys with high stream power favor sediment transport over deposition. Overall, more than half of the Zn released by mining remains stored in floodplain deposits within the watershed. The remobilization of Zn from storage is more likely in the upstream and mid-basin reaches where high stream power increases rates of lateral channel migration. Channels in the lower valley lack the stream power to migrate laterally and remobilize the large Zn mass stored in overbank sediments. [Key words: floodplains, Zn contamination, mining, stream power, Wisconsin.]     

基于地形因子的千米尺度景观生态廊道布局研究

土地利用类型并不是景观类型唯一的描述方式, 生态服务价值的估算和地形指标的纳入更有助于反映景观的空间差异性。应用地形因子与生态价值两类指标, 对关中-天水经济区1 km栅格尺度下生态廊道空间布局形式进行研究, 结果如下:① 相关性分析表明地形因子对生态价值分布有重要影响, 经过统一阈值的脊线谷线提取发现, 对生态价值提取出的高值或低值区域几乎同时也是地形上的山脊线或山谷线, 过渡带基本重合;② 提取山脊生态高值区域作为生境斑块, 通过最大生态阻力进行方向选择, 可得出研究区生态廊道空间布局, 由于廊道宽度可根据物种类型调整, 同时距离较短导致实现难度低, 增删节点与斑块不影响周边网络的拓扑关系, 因此结果应用性相对更强;③ 采用地形和生态服务价值作为衡量指标, 更能体现以像元为单位的景观功能一致性与差异性, 从而也避免了土地利用分类较粗、生境判断难度较大、相同阻力路径过多等一系列问题。本文结果是对千米尺度廊道布局的有效补充。