River channel change during the last 50 years in the middle Yangtze River, the Jianli reach

Intensive anthropogenic disturbances have affected the channel of the middle Yangtze River since the 1950s. This paper selects the Jianli reach as an example to examine human impact on channel change in the middle Yangtze River. 1:100,000 channel distribution maps from 1951, 1961 and 1975 and 1:25,000 navigation charts from 1981 and 1997 were employed to reconstruct channel change in the study reach. The result indicates that the channel, under the constraint of levees along the riverbanks, underwent a minor widening but frequent bank failure due to susceptible bank structure and increase in water discharge. The bank failure promoted bar growth in the channel. Cross-section changes and quantitative calculations of erosion and deposition based on the DEM derived from navigation charts present a pattern of over-bank sedimentation and riverbed incision. The stage and duration of floods have increased following levee construction and bank revetment.     

Channel response to a new hydrological regime in southwestern Australia

The Kent River flows from semi-arid headwaters in the agricultural (wheatbelt) region of Western Australia to a wetter and forested lower-catchment. It is set in an atypical fluvial environment, with rainfall decreasing inland towards a low-relief upper catchment. Replacement of native deep-rooted perennial vegetation with shallow-rooted seasonal crops has altered the hydrology of the upper catchment. Clearing for agriculture has also increased recharge of regional groundwater systems causing groundwater to rise and mobilise salt stores. This has increased stream salinity which has degradation riparian vegetation and decreased flow resistance. Elevated groundwater has also affected streamflow, increasing flow duration and annual discharge. The altered hydrological regime has affected geomorphic stability, resulting in channel responses that include incision and removal of uncohesive material. Channel response is variable, showing a high dependence on channel morphotype, channel boundary material and severity of salinity (degree of vegetation degradation). Response in confined reaches bounded by sandy material has been characterised by minor lateral bank erosion. In the fine-grained, wider, low-gradient reaches, mid-channel islands have been stripped of sandy sediment where vegetation has degraded. Following an initial period of high erosion rates in these reaches, the channel is now slowly adjusting to a new set of boundary conditions. The variable response has significant implications for management of salt affected rivers in southwestern Australia.     

Fiumara: a kind of high hazard river

Fiumara is a kind of gravel-bed river, very steep and short, which flow through the southern Italy mountain chains, in Sicilia and Calabria regions. These streams drain mountain areas only, and are subject to a Mediterranean climate. They have a great transport and erosion capacity because of their flow regime, dominated by episodic flash floods alternated with long periods of inactivity during which their beds become completely dry. During this last century, the natural equilibrium of these particular alluvial environments has undergone notable modifications caused also by human activities. The effects of such works are investigated in terms of river dynamics, and some local examples are reported and discussed; some suggestions are made for recovery measures too.     

人类活动对北京东灵山山顶草甸植被的影响及草甸植被的保育对策

通过对北京东灵山海拔 1500 m以上草甸植被资源的调查，共获得41个面积为 4 m×4 m的样方资料。将不同草甸群落按照人类活动的影响作用进行归类，并对各个草甸群落的生境和群落特征进行分析，结果表明：①东灵山山顶草甸植被以人类活动影响下形成的次生草甸群落为主，原生性草甸仅分布在海拔 2000 m以上的山顶及其邻近地段；②种类组成最丰富的草甸群落位于海拔1510～1900m的地段，这是自然条件和人类活动共同作用的结果；③旅游活动的影响已经使山顶原生性草甸受到威胁，局部地段草甸植被退化严重；④限制马匹活动，适时、适度提高缆车票价，在草甸分布地段部分拆除并制止新建饭店、旅馆，实行旅游功能分区规划和管理，有针对性地开展草甸承载力研究等，是现阶段草甸植被保育的重要措施。     

西方"马克思主义"地理学--人文地理学的一个重要流派

本文全面地概述了西方“马克思主义”地理学的形成过程、理论脉络和研究方法以及新的进展,并着重介绍了西方“马克思主义”地理学的三个核心内容,即政治经济学分析、空间理论和社会－自然关系理论,最后对西方“马克思主义”地理学进行了简要的评论。     

青海湖地区人类活动对生态环境影响及其保护对策

本文根据作者近年来对青海湖地区人类活动和环境现状的调查，探讨了该区人类活动和环境和现状的调查，探讨了该区人类活动和生态环境的关系及特点，分析了人为活动对生态与环境影响的空间、时间及动态特征；并针对该区目前的环境状况提供出保护对策。     

地下水资源与江苏地面沉降研究

介绍了当前国内外水资源研究的发展趋势（研究特点、总的趋势）。强调要从整体、系统的观点出发，把资源与环境作为一个整体系统来研究。不仅研究资源、环境的自然属性，还加强其社会属性的研究，关注人类活动对自然生态系统的影响机制。其次，介绍了水资源研究的前沿领域。从江苏地面沉降现状出发，分析当前研究特点、存在问题，提出了相应的长江三角洲地面沉降研究建议。     

王士性的地理学思想及其影响

王士性是明代后期的大地理学家,其贡献主要体现在人文地理方面。王士性深刻认识到地理学的区域性特点,注意分析各地自然环境与人文因素的差异。在经世实用思潮的影响下,他形成了后来称之为“郡国利病”的思想。王士性还具有动态性的观念,认为地理现象是在不断变化发展的。他同时又是一个环境决定论者。他的地理学思想对明清之际的学者,特别是顾炎武,产生很大的影响。     

Early human impact in the forest ecotone of southern High Asia (Hindu Kush, Himalaya)

The vegetation of the treeline ecotone of the southern declivity of arid High Asia (Hindu Kush, northern areas of Pakistan; Himalaya, northern central Nepal) is dominated by hedgehog-like open dwarf shrublands of thorny cushions. Since climatically sensitive ecotones are always also sensitive to human impact, the question arises whether the current lack of forests is a result of the Subboreal climate decline or of human impact. Due to inadequate knowledge of the pollen flora and of ecological indicator values of the plants, pollen analyses in High Asia have mainly been limited to the regional verification of globally known climatic impulses. However, the role of human impact on regional vegetation patterns has been widely neglected. We postulate that today's open dwarf shrublands replace woodlands and forests. Isolated vigorous juniper trees and successful reforestation appear to confirm our hypothesis. An abrupt decline of Pinus forests before 5700 and 5400 ka cal yr BP can be demonstrated. As the first indicator pollen of human impact appeared at both sites synchronous with the forest pollen decline, we infer human impact to be a more decisive cause for this environment change superimposing the effects of a climatic deterioration. The forests were displaced by open dwarf shrublands.     

On probabilities of avalanches triggered by alpine skiers. An empirically driven decision strategy for backcountry skiers based on these probabilities

Most fatal avalanche accidents in the Alps are caused by skiers and snowboarders. It has been one aim from the beginning to give guidelines for backcountry skiers in order to avoid avalanche accidents. About 10 years ago, the mountain guide Werner Munter developed a strategy for backcountry skiers whether to go or not to go on a skiing tour. However, his decision strategy has a lack of empirical evidence because he does not take into account incidents without avalanche accidents. This article proposes a decision strategy for backcountry skiers based on probabilities of a logistic regression model using variables, such as danger level, incline of the slope and aspect of the slope, which turned out to be the most important ones. Additional information on frequencies of skiers on slopes under specific conditions is included in the model. We used accident data and avalanche forecasts in Tyrol reported by the Tyrolean avalanche information service within three seasons (1999–2002, 497 days of observations) for model building. Additionally we carried out a holdout validation using data of the same type within two seasons (2002–2004, 314 days of observation) in order to check the accuracy of the model. Our proposal shows a remarkable correlation with Munter’s method.