A sediment budget for a cultivated floodplain in tropical North Queensland,Australia     

Fleur Visser  Christian H. Roth  Robert Wasson  Gerard Govers 《地球表面变化过程与地形》2007,32(10):1475-1490

Sugarcane is grown on the floodplains of northern Queensland adjacent to the Great Barrier Reef lagoon. Sediment and nutrient loss from these sugarcane areas is considered a potential threat to coastal and marine ecosystems. To enable sugarcane cultivation, farmers have structured the landscape into different elements, comprising fields, water furrows, ‘headlands’ and drains. In order to apply appropriate management of the landscape and reduce export of sediment, it is important to identify which of these elements act as sediment sources or sinks. In this study erosion and deposition rates were measured for the different landscape elements in a subcatchment of the Herbert River and used to create a sediment budget. Despite large uncertainties, the budget shows that the floodplain area is a net source of sediment. Estimated sediment export varies between 2 and 5 t ha^?1 y^?1. The relative importance of the landscape elements as sediment sources could also be determined. Plant cane is identified as the most important sediment source. Water furrows generate most sediment, but are a less important source of exported sediment due to their low connectivity. Headlands and minor drains act as sediment traps. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Contracts and member checks in qualitative research in human geography: reason for caution?   总被引：3，自引：0，他引：3  

Matt Bradshaw 《Area》2001,33(2):202-211

Contracts with, and member checks by, research participants are increasingly recommended in qualitative research in human geography. However, differences in qualitatively researching 'the powerful', as opposed to researching 'down' mean that contracts and member checks may need to be approached with caution regarding the former. The possibility of the censorship of critique by powerful research participants is exemplified in this article, and a number of more general dilemmas in qualitatively researching 'up' are also discussed. Finally, some choices which might help address possible difficulties in qualitatively researching the powerful are outlined.  相似文献   

Land use changes in the environs of Moscow   总被引：1，自引：0，他引：1  

Grigory Ioffe  & Tatyana Nefedova 《Area》2001,33(3):273-286

This paper focuses on several aspects of land use change in Russia during the 1990s with a particular focus on the environs of Moscow. These aspects include modes of farming, recreation, ownership of land, and concentric zones of outwardly declining land use intensity that resemble Von Thunen's economic landscape. These zones are given special attention. In contrast to other land use aspects, the analysis of which indeed reveals a fair amount of change bringing the environs of Russian cities one step closer to their Western counterparts, concentric agricultural land use patterns with outwardly declining productivity suggest continuity rather than change.  相似文献   

Response of alpine chironomid communities (Lake Chuna, Kola Peninsula, northwestern Russia) to atmospheric contamination   总被引：1，自引：0，他引：1  

Boris Ilyashuk  Elena Ilyashuk 《Journal of Paleolimnology》2001,25(4):467-475

A short sediment core from the deepest part of an alpine lake (Lake Chuna, Kola Peninsula, northwestern Russia), covering about the past 200 yrs of sediment accumulation, was analysed for chironomid head capsule remains. The lake has been receiving acidic precipitation and heavy metals loading from the atmosphere since the 1940's. A total of 22 chironomid taxa were recorded. The most important taxa were typical elements of oligotrophic lakes, i.e.Micropsectra insignilobus, Paratanytarsus penicillatus, Stictochironomus spp. and Heterotrissocladius marcidus. Based on the cluster analyses results for the reconstructed environmental variables and chironomid communities, three developmental stages were distinguished from the lake history: (1) Natural ontogeny stage (before ~1945); (2) Initial stage of anthropogenic ontogeny (~1945-~1982); and (3) Anthropogenic ontogeny stage (~1982-~1996). During the first period, the changes in the chironomid fauna were characterized as an anthropogenically undisturbed community, with M. insignilobus dominating (46-66%). The changes during the second period reflected the initial phase of anthropogenic succession associated with the beginning of acidification and heavy metal pollution. The main species showed opposite distributional patterns in this period; the abundance of the group M. insignilobus/Stictochironomus spp. decreased, whereas the abundance of P. penicillatus/H. marcidus increased. The third period was characterized by a major shift in the faunal assemblages, from M. insignilobus to other dominant species including P. penicillatus (19-30%). The increases of Orthocladiinae relative abundance and total organic content in the uppermost sediment layers may be explained by a decrease in lake productivity. The decreases of cold-stenothermal taxa Stictochironomus spp. and M. insignilobus in the uppermost sediment layers can be explained by the global warming during the 20th century. The lake ecosystem is likely to be affected by both inputs of airborne contaminants and climate changes.  相似文献   

浅议地球系统的复杂性及非线性   总被引：1，自引：0，他引：1  

王瑞廷 《世界地质》2001,20(4):313-320

结合复杂性科学的产生及发展历程，认为复杂性科学对研究地球系统复杂性及非线性具有重要的理论指导和方法论意义。同时，在论述地球系统基本属性的基础上总结了地球系统复杂性及非线性的具体表现，即地球系统的层次性，无特征尺度性，开放性，相干性，临界性，自组织性和其动力学行为的自相似性及分形性。认为地球系统是总体上远离平衡，时空延展的多层圈综合集成，连续开放的复杂耗散动力巨系统。随着复杂性科学和地球系统的复杂性及非线性研究的不断深入，在21世纪，地球科学研究将会取得理论上的重大突破和飞跃。  相似文献   

Hailstorm Loss Modelling and Risk Assessment in the Sydney Region,Australia   总被引：2，自引：0，他引：2  

Leigh  R.  Kuhnel  I. 《Natural Hazards》2001,24(2):171-185

This paper summarises work undertaken at the Natural Hazards ResearchCentre with regard to the compilation, climatological analysis and lossmodelling application of hailstorm data for the greater Sydney region. Itdiscusses the results from two associated research areas: ENSO-relatedclimatological analysis of hailstorm data, and insurance sector orientedrisk assessment of hail losses in the Sydney basin. The two complementaryprojects led to the development of HailAUS, the first hail loss model for amajor urban area in Australia. The hazard occurrence module of the hailloss model is based on a comprehensive, good quality hail data set, whoseinterannual variability has previously been analysed with regard to the ENSOsignal. The paper presents the major results of the local hail data climatology,and outlines the structure of the hail loss model. The important practicalapplications that result from the collection and analysis of good qualityclimatological data are noted.  相似文献   

Seasonal Forecasting for Climate Hazards: Prospects and Responses     

Murphy  Sarah J.  Washington  Richard  Downing  Thomas E.  Martin  Randall V.  Ziervogel  Gina  Preston  Anthony  Todd  Martin  Butterfield  Ruth  Briden  Jim 《Natural Hazards》2001,23(2-3):171-196

One of the most promising developments for early warning of climate hazards is seasonal climate forecasting. Already forecasts are operational in many parts of the tropics and sub-tropics, particularly for droughts and floods associated with ENSO events. Prospects for further development of seasonal forecasting for a range of climatichazards are reviewed, illustrated with case studies in Africa, Australia, the U.S.A. and Europe. A critical evaluation of the utility of seasonal forecasts centres on vulnerability, communicationchannels, and effective responses. In contrast to short-term prediction, seasonal forecasts raise new issues of preparedness and the use of information.  相似文献   

Application of short-wave infrared spectroscopy to define alteration zones associated with the Elura zinc–lead–silver deposit, NSW, Australia     

Yanyan Sun  Philip K. Seccombe  Kai Yang   《Journal of Geochemical Exploration》2001,73(1):63

Short-wave infrared reflectance spectra obtained from a Portable Infrared Mineral Analyser (PIMA) have been used to define alteration zones adjacent to base metal sulfide ore bodies at the Elura Mine, Cobar, Australia. The spectroscopic work identified white mica (sericite), chlorite and carbonates of hydrothermal origin in the alteration zones associated with the ore bodies. Weathering, alteration and ore zones can be discriminated by variations in the intensity and wavelength of relevant absorption features. Hydrothermal alteration is classified into four principal types, namely sericitic, silicic, chloritic and carbonate alteration. The first three types comprise overprinting hydrothermal assemblages of quartz, sericite, chlorite, ankerite, siderite, calcite and sulfides developed in strongly altered metasiltstone and slate of Early Devonian age, adjacent to the zinc–lead–silver mineralisation. An extensive zone of carbonate alteration, manifested as porphyroblasts of siderite in the host metasediments, is recognised beyond the zones of strong alteration. Spectral analysis is consistent with the mineralogical data obtained from XRD and XRF analyses and defines the limits of the alteration zones to distances of about 80 m around the ore bodies. The study demonstrates the potential for spectral analysis to assist with drill hole logging and the identification of alteration zones as part of mineral exploration and development programs.  相似文献   

Dietary studies on exotic carp (<Emphasis Type="Italic">Cyprinus carpio</Emphasis> L.) from two lakes of western Victoria,Australia     

Tariq A. Khan 《Aquatic Sciences - Research Across Boundaries》2003,65(3):272-286

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地质系统的复杂性--地质科学的基本问题(Ⅱ)   总被引：10，自引：0，他引：10  

於崇文 《地球科学》2003,28(1):31-40

笔者根据其所提出的“地质作用与时空结构是一切地质现象的本质与核心”的自然哲学理念将地质科学的学科体系划分为地球物质的成分与结构、地质作用、地质学场与地质系统的演化等四大基本领域,它与9个重大基础地质问题以及与其相关的基础理论问题相对应（表2）,笔者将其已发表的地质科学的复杂性理论“地质作用的临界过程动力学－地质系统在混沌边缘分形生长”应用于研究9个重大基础地质问题,着重对于其中所包含的主要基础理论问题的实质及其理论与研究方法作较深入而简要的剖析。目的是通过将地质系统的复杂性作为地质科学的基本问题的新视角对古老而常新的地质科学进行再认识,将重大基础地质问题的研究提高到非线性科学和复杂性理论的层次,并实现地质科学向精确科学的跨越,取得突破性进展。  相似文献