The interaction between armouring and particle weathering for eroding landscapes

The interaction between particle weathering and surface armouring and its effect on erosion has been investigated. The effect of soil armouring is to decrease sediment transport with time by preferentially stripping away fine particles. On the other hand the effect of weathering, which breaks down the particles in the armour, is generally believed to increase erosion. By extending an existing armouring model, ARMOUR, and using a variety of published weathering mechanisms this interaction has been explored. The model predicts that while this is generally true, in some cases erosion can be decreased by weathering. When the particles generated by weathering were approximately of equal diameter, erosion increased while armouring decreased. When weathering produced very fine particles by spalling, erosion increased and armouring also increased. When weathering produced a range of particles from fine to coarse, the armour layer broke down and erosion decreased relative to the no‐weathering case. This latter decrease in erosion was due to the high entrainment of coarser transportable materials from the bed decreasing the sediment transport capacity of the flow. In these studies clear regimes could be identified where erosion was limited by either the energy of the flow alone (i.e. ‘transport‐limited’), or the rate of weathering (‘weathering‐limited’); however, for some mechanisms there was an interaction between the two, which we called ‘weathering/transport limited’. Copyright © 2006 John Wiley & Sons, Ltd.     

Effects of variable attribute weights on landform classification

This paper focuses on the attribute weight issue and advocates use of modi?able attribute weights in terrain‐based environmental analysis and classi?cation. A question was asked: ‘How much will the result of a terrain‐based environmental analysis be affected if the weights of used terrain attributes are changed?’ The literature on landform classi?cation and the fuzzy k‐means method was reviewed in particular to help clarify the background and importance of this weight assignment issue. As an example, the effects of modifying attribute weights were evaluated for fuzzy k‐means landform classi?cation in a case study area. A total of 102 classi?cations were compared with each other and with a soil map, and comparison methods were speci?cally designed to evaluate the differences between these classi?cations. The results show that fuzzy k‐means landform classi?cation is sensitive to weight adjustments of adopted terrain attributes. The sensitivity is particularly high when the attribute weights started to be tuned away from the standard (i.e. uniform) weight of one. Better matching between landform classi?cation and a soil map may be produced when attribute weights are tuned. In all, we advocate the widespread adoption of an exploratory attitude in assigning attribute weights for environmental analysis and classi?cation. Copyright © 2006 John Wiley & Sons, Ltd.     

剑门地貌特征、成因及与丹霞地貌之比较

剑门地貌见于四川盆地北部的剑阁县剑门关一带,是一种特定的砾岩地貌,以发育砾岩悬崖绝壁、砾岩关隘、砾岩峡谷、砾岩山峦、砾岩峰丛等为特征,规模宏大,气势如虹。龙门山山前广泛分布,景观独特,与广东丹霞地貌显著不同。     

广州莲花山的人工丹霞地貌和旅游开发

通过实地考察,概述广州番禺莲花山与粤北丹霞山地质地貌的异同,从丹霞地貌角度阐述这座古石矿场“人工无意夺天工”形成的陡崖,岩洞,石墙,石巷,岩湖,石柱,石门,石桥等人工丹霞奇观,并对这座以全国罕有古石矿场为主景的莲花山旅游区的进一步开发,提出了讨论意见。     

Post-Palaeozoic evolution of weathered landsurfaces in Uganda by tectonically controlled deep weathering and stripping

A model for the evolution of weathered landsurfaces in Uganda is developed using available geotectonic, climatic, sedimentological and chronological data. The model demonstrates the pivotal role of tectonic uplift in inducing cycles of stripping, and tectonic quiescence for cycles of deep weathering. It is able to account for the development of key landforms, such as inselbergs and duricrust-capped plateaux, which previous hypotheses of landscape evolution that are based on climatic or eustatic controls are unable to explain. Development of the Ugandan landscape is traced back to the Permian. Following late Palaeozoic glaciation, a trend towards warmer and more humid climates through the Mesozoic enabled deep weathering of the Jurassic/mid-Cretaceous surface in Uganda during a period of prolonged tectonic quiescence. Uplift associated with the opening South Atlantic Ocean terminated this cycle and instigated a cycle of stripping between the mid-Cretaceous and early Miocene. Deep weathering on the succeeding Miocene to recent (African) surface has occurred from Miocene to present but has been interrupted in the areas adjacent to the western rift where development of a new drainage base level has prompted cycles of stripping in the Miocene and Pleistocene.     

对陡坡陡崖引发地质灾害的潜在影响范围进行建模分析

陡坡陡崖作为一种特殊的地形地貌,是造成滑坡、泥石流等各种地质灾害的重要因素之一。由陡坡陡崖引发的地质灾害会破坏人造地物,对人类的生命财产安全造成严重危害。本文利用DEM数据提取了浙江省温州市的陡坡陡崖,对温州市陡坡陡崖的影响范围进行系统研究,构建了温州市陡坡陡崖的潜在滑坡方向模型,并确定其对人造地物（如道路、房屋）的影响。本文主要研究内容有以下两个：①提取陡坡陡崖并对其潜在滑坡方向进行建模;②根据影响范围提取受影响的人造地物并建立基础数据库。结果表明,温州市的陡坡陡崖数量多,分布范围广且集中,其引发的地质灾害会对人造地物造成严重的潜在影响。本文构建的温州市基础数据库可以描述陡坡陡崖潜在影响的房屋和道路的位置,确定灾害重点防治区域,为温州市的灾害防治工作提供服务。     

新疆乌恰康苏地区构造地貌与景观生态格局研究

新疆乌恰康苏地区位于西昆仑山与西南天山对冲作用形成的盆山耦合带,其构造地貌具有显著的山地-平原分布格局特征.文章以"3S"技术为基础进行构造地貌填图,划分新疆乌恰康苏地区的景观类型,研究构造地貌对该区域景观生态格局的影响.采用垂向山地-平原构造地貌为指标,划分5个景观类;以土地利用类型+植被覆盖为指标,划分6个景观型;...     

辽东山地老秃顶子冰缘地貌植物群落类型及基本特征

基于48个样地的群落调查数据,运用TWINSPAN分类方法,对辽东山地老秃顶子冰缘地貌植物群落类型进行了划分,并对群落结构、种类组成和生活型谱进行了系统研究.结果表明:老秃顶子冰缘地貌植被可划分为16个森林群系、6个灌丛群系,归并为落叶阔叶林、针阔混交林、暗针叶林、矮曲林、灌丛、灌草丛6个植被型.其中,石海地貌主要发育灌丛和灌草丛,也有针阔混交林和矮曲林分布;石河地貌主要发育针阔混交林和落叶阔叶林,也有暗针叶林分布;石流坡地貌主要发育针阔混交林、落叶阔叶林和灌丛,也有矮曲林分布.老秃顶子冰缘地貌植被由68科138属193种维管束植物组成;石海与石河间植物群落物种组成属中等不相似,而石河与石流坡间属中等相似.老秃顶子冰缘地貌植物群落中高位芽植物占38.0%,隐芽植物占36.3%,地面芽植物占21.8%,地上芽植物和一年生植物均很少,反映出辽东山地冰缘地貌区具有夏季温暖多雨、冬季寒冷漫长的气候特点.相对而言,石海、石流坡地貌中隐芽植物较多,石河地貌中高位芽植物较多,表明石海、石流坡地貌具有更为冷湿的小气候环境.     

《中国西部地区典型地貌图集》设计与编制

针对我国西部地区地貌的专题地图集空缺的现状,《中国西部地区典型地貌图集》的编制填补了这一空白,该图集是以表达我国西部地区十省(市、自治区)典型地貌形态特征为主题的区域性专题地图集,是国家西部测图工程成果之一。该文阐述了该地图集的概况,重点从图集编制原则、内容结构、表达方法、装帧设计等各方面详细介绍了该地图集的内容设计与编制特色。地图集为地学相关领域进行科学研究、测绘部门地貌表达以及相关院校科研教学等提供技术资料。