Ian C. Fuller

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?’

River response to high-frequency climate oscillations in southern Europe over the past 200 k.y.

A 200 k.y. chronology of river response to climate-related environmental change has been established for northeast Spain using newly developed luminescence dating techniques. This constitutes the best-documented record of late Quaternary river behavior currently available for the North Atlantic region and enables fluvial stratigraphies to be compared with high-resolution ice core and marine oxygen isotope climate series. Pleistocene and Holocene river aggradational episodes coincide with stadial or neoglacial events, while phases of river incision occur during interstadial or interglacial periods. Alluviation and erosion cycles would appear to track variations in sediment supply controlled by vegetation cover and winter storm frequency.

Quantifying channel development and sediment transfer following chute cutoff in a wandering gravel-bed river

Abstract Three-dimensional morphological adjustment in a chute cutoff (breach) alluvial channel is quantified using Digital Elevation Model (DEM) analysis for a ca. 0.7 km reach of the River Coquet, Northumberland, UK. Following cutoff in January 1999, channel and bar topography was surveyed using a Total Station on five occasions between February 1999 and December 2000. Analysis of planform change coupled with DEM differencing elucidates channel and barform development following cutoff, and enables quantification of sediment transfers associated with morphological adjustment within the reach. This exercise indicates an initial phase of bed scour, followed by a period characterised by extensive bank erosion and lateral channel migration where erosion (including bed scour) totalled some 15,000 m3 of sediment. The channel in the post-cutoff, disequilibrium state is highly sensitive to relatively low-magnitude floods, and provision of accommodation space by bank erosion encouraged extensive lateral bar development. Bar development was further facilitated by infilling of channels abandoned by repeated within-reach avulsion and large-scale aggradation of sediment lobes deposited by higher magnitude floods. Calculations indicate that at least 6600 m3 of sediment was deposited on emerging bars within the reach over the survey period, and >2300 m3 deposited within the channel. Sediment losses from the reach may have exceeded 6500 m3.

Evaluation of student learning experiences in physical geography fieldwork: paddling or pedagogy?

This paper reports a project carried out with first-year geography students undertaking physical geography fieldwork. An experiment within the context of fluvial studies tests the effectiveness of student learning using contrasting approaches based on analytical-prediction and descriptive-explanation. The results, based on marks analysis and a review of student feedback, indicate that in the short term the traditional descriptive-explanation approach is significantly more conducive to student learning than the analytical-predictive mode.

Quantifying the geomorphic impacts of a lake-breakout lahar, Mount Ruapehu, New Zealand

At 11:18 h (New Zealand time, GMT +12) on 18 March 2007 an impoundment of 0.01 × 10 6 m 3 of tephra collapsed, releasing 1.3 × 10 6 m 3 of water from Crater Lake at 2536 m elevation on Mount Ruapehu. The lahar traveled 200 km along the Whangaehu River. Aerial LiDAR surveys of the upper 62 km of flow path were made before and after the lahar. We present here the first large-scale quantification of the geomorphic impact of the dam-break flood along with the rates and controls on its sediment entrainment and deposition. The flood mobilized a net value of 2.5–3.1 × 10 6 m 3 of boulders, gravel, and sand over the first 5 km of travel to form a lahar of at least 4.4 × 10 6 m 3 passing instruments at 6.9 km. LiDAR volume-transfer calculations match dynamic measurements made. After a logarithmic increase in cumulative net sediment entrainment, the lahar appeared to reach its maximum sediment-carrying capacity at 22 km. Patterns of alternating sediment erosion and deposition occurred that dominantly reflect a combination of channel morphology and confinement on the local sediment-carrying capacity of the flow.

New Zealand and UK Holocene flooding demonstrates interhemispheric climate asynchrony

The timing and controls of interhemispheric Holocene climate change have remained poorly understood, primarily because of the absence of well-dated and continuous climatic records in terrestrial environments. Here we report a new probability-based meta-analysis of 1185 14 C dates from fluvial sedimentary sequences in New Zealand and the UK, which provides a robust means of identifying centennial- and multicentennial-length episodes of Holocene river flooding. Statistical analysis shows that prior to large-scale human impact, which began at ca. 1000 cal. yr B.P., the incidence of extreme floods in New Zealand and the UK has been largely asynchronous during the Holocene. Major periods of flooding are controlled by large-scale shifts in atmospheric circulation, which alter the frequency of extreme precipitation events. Our novel synthesis demonstrates that short-term climate change, of sufficient magnitude to modify flooding regimes, was out of phase in the temperate maritime regions of the Northern and Southern Hemispheres during much of the Holocene. This supports recent evidence from both glacial and marine records that Holocene climate changes may have been antiphased between the polar regions and that this could have been related to variation in the strength of deep water formation.

CDW photogrammetry of low relief fluvial features: accuracy and implications for reach‐scale sediment budgeting

Terrestrial photogrammetry enables rapid survey to be undertaken in the fluvial environment, a crucial factor when assessing highly dynamic features. In addition, it permits the generation of terrain surfaces at a level of detail which, given equal time constraints in the field, far exceeds the detail permitted by conventional tacheometric survey. This study details the levels of accuracy that can be achieved using the RolleiMetric Close-range Digital Workstation (CDW) photogrammetric survey technique on a variety of low relief fluvial geomorphic features (lateral, point and mid-channel bars) ranging from 10 m 2 to 100 m 2 . The CDW software processes image data from an array of photographs and establishes a set of three-dimensional co-ordinates for the photographed object. The accuracies achieved across all bar surfaces were well within the resolution defined by the maximum size of the gravel on the bar surface (mean errors were between 0·026 and 0·057 m). The use of CDW photogrammetry does not require experienced personnel; however, care must be taken during the survey to minimize edge effects and to ensure that target density is sufficient to produce a terrain model that is accurate to within the limits of the surface sediment size. Guidance on target density as a function of terrain roughness is given to aid the user. A methodology is suggested that will allow CDW to be incorporated into sediment budgeting techniques, improving the level of achievable accuracy.

Geomorphic Work during a “150-Year” Storm: Contrasting Behaviors of River Channels in a New Zealand Catchment

Abstract The geomorphic work accomplished during an extreme storm event by three primary tributaries in the western Manawatu river catchment (New Zealand) is assessed using sequential aerial photographs. Areas of floodplain and channel erosion were quantified as a measure of the work accomplished during floods triggered by a “150-year” storm in February 2004. Of the three rivers studied, the smallest (Kiwitea, 225 km2) accomplished the most geomorphic work, eroding 1.1 km2 of floodplain along a 30 km long reach. Here spatially discontinuous channel transformation was associated with large-scale bank erosion in response to a flood estimated to be more than five times bigger than the mean annual flood (annual recurrence interval [ARI] ∼100 years). Total energy expenditure in the Kiwitea flood was ∼14,900 × 103 joules. The larger Pohangina (547 km2) and Oroua (329 km2) rivers were less effective, expending ∼14,400 × 103 joules and ∼5,300 × 103 joules and eroding 0.36 and 0.6 km2 of floodplain, respectively. The contrasting amount of geomorphic work between these tributaries relates to valley floor and channel configurations, which prime discrete reaches for instability, sensitizing them to perturbation by this flood event. In the Kiwitea, greatest erosion occurred where floodwaters were confined by terrace bluffs at bends that locally enhance stream powers. The wider channels of the Pohangina and Oroua Rivers wander across broader gravelly floodplains, permitting widespread dissipation of flood flows across the wider active channel and valley floor. Hydrologic, hydraulic, and geomorphic variables thus explain the variability in geomorphic work accomplished during the event. Ultimately, diverse channel behaviors reflect varied catchment and reach sensitivity to the flood event.

Annual sediment budgets in an unstable gravel-bed river: the River Coquet, northern England

Abstract Sediment budgeting procedures based on analysis of three-dimensional morphological change provide a useful mechanism by which rates and patterns of fluvial sediment erosion, transfer and deposition can be monitored. This paper presents results from an annual sediment budgeting programme established in a 1-km long piedmont reach of the gravel-bed River Coquet in Northumberland, northern England. The study reach has a locally braided channel planform and has experienced lateral instability over at least the past 150 years. Annual sediment budgets for 1997–1998 and 1998–1999 have been based on tacheometric survey of: (i) 15 monumented channel cross-profiles; and (ii) channel margins and gravel-bar morphology. Survey data have been analysed for each discrete morphological unit (differentiating channel and complex bar assemblages) within 17 sub-reaches of the study reach using Arc/Info™ GIS. The morphological sediment budgeting techniques used to generate these reach-scale budgets may be particularly valuable in unstable gravel-bed rivers due to the inherent difficulties in measuring bed-load transport. The results show considerable variability in rates and patterns of within-reach sediment transfer between the successive surveys. The channel at Holystone is characterized by substantial within-reach sediment transfer, with minimal net export downstream. This behaviour appears to be characteristic of UK gravel-bed piedmont rivers.

Twenty-First Century Calving Retreat of Tasman Glacier, Southern Alps, New Zealand

Abstract Tasman Glacier is the largest glacier in the New Zealand Southern Alps. Despite a century of warming and down-wastage, the glacier remained at its Little Ice Age terminus until the late 20th century. Since then, a proglacial lake formed, and comparatively rapid calving retreat has been initiated. In this paper we use sequential satellite imagery to document terminus retreat, growth of supraglacial ponds, and expansion of the proglacial Tasman Lake. Between 2000 and 2008, the glacier terminus receded a maximum of c. 3.7 km on the western margin, and the ice-contact Tasman Lake expanded concomitantly. This northward expansion of Tasman Lake up-valley proceeded at a mean annual rate of 0.34 × 106 m2 a−1 over 2000–2008, attaining a surface area of 5.96 × 106 m2 in May 2008, with a maximum depth of c. 240 m. Terminus retreat rates (Ur) vary in both space and time, with two distinct periods of calving retreat identified during the study period: 2000–2006 (mean Ur  =  54 m a−1) and 2007–2008 (mean Ur  =  144 m a−1). Terminus retreat can also be categorized into two distinct zones of activity: (1) the main ice cliff (MIC), and (2) the eastern embayment ice cliff (EEIC). During the period 2000–2006, and between 2006 and 2008 for the EEIC, the controlling process of ice loss at the terminus was iceberg calving resulting from thermal undercutting. In contrast, the retreat of the MIC between 2006 and 2008 was controlled by buoyancy-driven iceberg calving caused by decreasing overburden pressure as a result of supraglacial pond growth, increased water depth, and rainfall. The presence of a >130-m-long subaqueous ice ramp projecting from the terminal ice cliff into the lake suggests complex interactions between the glacier and ice-contact lake during the 8–10 km of possible future calving retreat.