David Higgitt

International Perspectives on the Effectiveness of Geography Fieldwork for Learning

This paper seeks to address assumptions on the effectiveness of fieldwork as a mode of learning in geography. This is approached from an international perspective, both in review of available evidence, which demonstrates a need for rigorous research into the issue, and in providing preliminary findings of research into the value of fieldwork from universities across three continents. Common themes to emerge concern the effectiveness of fieldwork in terms of learning and understanding of the subject: providing first-hand experience of the real world, whichever part of the world the students are in; skills development (transferable and technical); and social benefits. The extent to which fieldwork develops transferable skills depends on the context in which the fieldwork is undertaken. The paper points to avenues of future research to be investigated to deepen our understanding of the role fieldwork plays in student learning and to address the question, ‘how effective is fieldwork in improving learning?’

Sediment delivery to the Three Gorges: 2: Local response

Abstract Information on soil erosion and sediment yields is very limited in the immediate vicinity of the Three Gorges Project (TGP), although the inceptisols developed on Triassic shales and sandstones in this area are known to be highly susceptible to erosion. Estimated sediment yields for a small reservoir catchment (Yiwanshui) in Changshou County, downstream of Chongqing, are high (around 3500 t km−2 a−1) and similar to the data from 38 reservoir investigations in Sichuan basin, but exceeding the yields estimated in the feasibility studies for the TGP. The high sediment yield reflects severe soil erosion due to cultivation aligned with slope on steep slopes, which is very common throughout Sichuan Basin and particularly in the TGP area. The total sediment delivered to the Yangtze from the TGP area has been estimated, using small reservoir data and sediment load measured at hydrological stations. These are comparable with previous estimates but there is much temporal variability in sediment supply from different parts of the Three Gorges region, suggesting the importance of local impact on sediment flux. Resettlement of agricultural activity around the Three Gorges Reservoir is likely to further enhance soil erosion. Temporal changes in sediment yields are reconstructed by using caesium-137 (137Cs) dating techniques. They indicate significant changes resulting from human activity and rainfall variability during the past four decades. Comparing reservoir sedimentation against erosion estimates on catchment soils, derived from measurements, indicates that 84% of eroded soil is delivered to the reservoir and the remainder is deposited in valley floor paddy fields. It is estimated that over 60% of sediment is contributed from arable land. The trap efficiency of small catchment reservoirs, such as Yiwanshui, may be an important control on sediment delivery to the main channel of the Upper Yangtze.

Sediment delivery to the three gorges:: 1. Catchment controls

Abstract The paper examines sediment yield and its response to catchment disturbance and environmental variables in the Upper Yangtze basin, where the attention of environmentalists has been drawn to the Three Gorges Project (TGP). Information about the source and conveyance of sediment from the catchment area to the Three Gorges Reservoir has implications for management strategies. Methodologies for establishing the relationships between land cover, climatic and topographic variables with sediment yield are introduced. The analysis uses a sediment load data set, containing 250 stations with up to 30 years of measurement, a 1×1 km resolution land cover database and variables extracted from various geodatabases. The mean sediment load delivered from the Yangtze upstream of Chongqing is 318 Mt a−1, but the contribution from the Jialing tributary is higher in terms of specific sediment yield at 928 t km−2 a−1. Long-term sediment yield at Yichang has not exhibited an upward trend despite the evidence for increased soil erosion within the basin. Examination of sediment response to catchment disturbance and spatial variability in relation to controlling variables has been undertaken in an attempt to predict future sedimentation impacts. Time series analysis illustrates that significant increases in sediment yield have occurred over about 8% of the catchment area while about 3% have experienced decreasing sediment yields. The latter are associated with major reservoir schemes on the tributaries of the Yangtze. When the spatial pattern of sediment yields within the basin is analysed, “natural” climatic and topographic factors explain most of the variability in the relatively sparsely populated western part of the Upper Yangtze basin, but do not afford very good prediction in the more populated eastern part. Incorporation of land cover information does not provide additional explanation of spatial variability. Examination of the response of sediment delivery to catchment disturbance and environmental variables provides an illustration which may have some lessons for the management of the sedimentation problem in the Three Gorges Reservoir and a basis for modelling future changes in sediment delivery.

Estimating erosion rates on sloping agricultural land in the Yangtze Three Gorges, China, from caesium-137 measurements

The paper describes the application of caesium-137 measurements for estimating soil erosion rates in a small catchment in the Three Gorges region of the Yangtze River, China. The construction of the Three Gorges Dam has drawn attention to the impact of erosion and sedimentation, but there are relatively few quantitative estimates of sediment transfer for this area. The suitability of the fallout radionuclide, caesium-137, for the rapid appraisal of soil redistribu- tion in the steep and dissected terraced landscape of the Three Gorges is investigated here. Previous applications of the technique in Chinese agricultural environments have indicated the difficulty of obtaining reliable baseline fallout estimation. The integration of monthly rainfall data with a model of global strontium-90 fallout is developed to provide an independent estimate of baseline fallout, which is consistent with field measurements. The method also enables a mass balance model of caesium-137 mobility to be calibrated. Mean annual soil loss during the last four decades is estimated at 4500 t km y2 yr y1 . Erosion rates are strongly related to field slope angles but highly variable spatially. q 2000 Elsevier Science B.V. All rights reserved.

The Irrawaddy River Sediment Flux to the Indian Ocean: The Original Nineteenth-Century Data Revisited

The Irrawaddy (Ayeyarwady) River of Myanmar is ranked as having the fifth‐largest suspended load and the fourth‐highest total dissolved load of the world’s rivers, and the combined Irrawaddy and Salween (Thanlwin) system is regarded as contributing 20% of the total flux of material from the Himalayan‐Tibetan orogen. The estimates for the Irrawaddy are taken from published quotations of a nineteenth‐century data set, and there are no available published data for the Myanmar reaches of the Salween. Apart from our own field studies in 2005 and 2006, no recent research documenting the sediment load of these important large rivers has been conducted, although their contribution to biogeochemical cycles and ocean geochemistry is clearly significant. We present a reanalysis of the Irrawaddy data from the original 550‐page report of Gordon covering 10 yr of discharge (1869–1879) and 1 yr of sediment concentration measurements (1877–1878). We describe Gordon’s methodologies, evaluate his measurements and calculations and the adjustments he made to his data set, and present our revised interpretation of nineteenth‐century discharge and sediment load with an estimate of uncertainty. The 10‐yr average of annual suspended sediment load currently cited in the literature is assessed as being underestimated by 27% on the basis of our sediment rating curve of the nineteenth‐century data. On the basis of our sampling of suspended load, the nineteenth‐century concentrations are interpreted to be missing about 18% of their total mass, which is the proportion of sediment recovered by a 0.45‐μm filter. The new annual Irrawaddy suspended sediment load is \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape

Geochemical characteristics and fluxes of organic carbon in a human-disturbed mountainous river (the Luodingjiang River) of the Zhujiang (Pearl River), China.

364\pm 60

Applications of differential GPS in upland fluvial geomorphology

\end{document} MT. Our revised estimate of the annual sediment load from the Irrawaddy‐Salween system for the nineteenth century (600 MT) represents more than half the present‐day Ganges‐Brahmaputra flux to the Indian Ocean. Since major Chinese rivers have reduced their load due to damming, the Irrawaddy is likely the third‐largest contributor of sediment load in the world.

The Effectiveness of Student-Authored Field Trails as a Means of Enhancing Geomorphological Interpretation.

Fieldwork is a distinctive feature of geography in higher education and is therefore a subject that is likely to be scrutinised by an emerging international network. Originating from an Internet discussion, the paper considers the context of internationalism for the enhancement of fieldwork practices. These broadly comprise opportunities to debate and discuss pedagogic issues about fieldwork in an international forum and to facilitate more effective international fieldwork opportunities and exchange. In examining specific issues affecting internationalisation, attention is drawn to the frequently implicit assumptions about the value of fieldwork and the need to foster research on the delivery of fieldwork objectives.