ALBERT

Description: The discovery that orbital variations are the driving force behind Quaternary climate change provides an impetus to set local and regional records of environmental change into the global context, a principle that has been strongly embraced by Quaternary scientists working in New Zealand. Their major achievements and significant current initiatives are reviewed here. The importance of the New Zealand Quaternary stems from its geographical context: a climatically sensitive, remote oceanic, southern location spanning 17 degrees of the mid-latitudes; an obliquely convergent plate boundary setting resulting in a high mountain range athwart the prevailing westerlies, active volcanism, a youthful and dynamic landscape, and mountains high enough to maintain glaciers today; and a remarkably short prehistory. The resultant records show marked environmental changes due not only to climatic oscillations but also to vigorous, active tectonism and volcanism. The Taupo Volcanic Zone, containing the world's strongest concentration of youthful rhyolitic volcanoes, has produced at least 10 000 km3of magma in the last 2 Ma. Climatic interpretations of records from marine sediments in the New Zealand region, together with several long sequences of alternating marine and terrestrial sediments, indicate broad synchrony with Northern Hemisphere events (within limitations of dating), although there are differences in detail for shorter-term climatic events. It is not yet certain that glacial advances coincided precisely with those in the Northern Hemisphere or were of similar duration. Late Cainozoic glaciation commenced c. 2.6-2.4 Ma but the record of glacial deposits is fragmentary and poorly dated except for the most recent events. The Last (Otira) Glaciation, from c. 100-10 ka, was characterized by at least five glacial advances including during the Last Glacial Maximum from 25 to 15 ka, when snowlines fell by 600-800 m. New Zealand evidence for cooling during the Younger Dryas stade is equivocal whilst isotopic records from speleothems, and other data, indicate warmer and wetter conditions from 10-7 ka, broadly conforming with records from mid-latitude Northern Hemisphere locations. Future advances will require sampling at shorter timescales, improvements in the accuracy and precision of existing dating methods and the development of new ones, extension of palaeoecological techniques to cover the full potential of new Zealand's diverse biota, and a stronger emphasis on quantification of palaeoclimatic parameters.

Description: The glaciers and snowfields of the Southern Alps of New Zealand are the most significant in the Southern Hemisphere outside Antarctica and South America. The most substantial data on Southern Hemisphere glacier fluctuations come from New Zealand. The nature and behaviour of New Zealand's glaciers are also of wider scientific interest, because they are highly sensitive, high input-output systems that represent the temperate, maritime end of the glacier process-behaviour continuum. The areal extent and volume of glaciers and snow are outlined and an assessment is made of their scientific relevance and of their importance as resources and hazards. The main themes and progress of research on glaciers and snow, including snow avalanches, are reviewed. Glacier research has concentrated on only a few key glaciers and has focused on understanding glacier change. Main topics covered in this review relate to this focus and include fluctuations in termini, other mass balance signals and response to climate variability. Research on mass balance processes, glacier dynamics and glacier hydrology is also outlined. Seasonal snow has received less attention until recently. The main emphasis has been on quantification and past variability and its contribution to river flow, particularly in the most important hydroelectric power catchments of the South Island. Some field measurements have been made of the energy balance over snow. Research on snow avalanches has grown as the demands of winter recreation and alpine tourism have increased the hazard. Research first concentrated on production of avalanche atlases for the most hazardous areas and on quantifying the nature of the hazard. Subsequently, there has been a shift towards more process studies that are related to avalanche formation and runout distance. The main gaps in research on glaciers and snow are identified and key areas for future work proposed. There is an urgent need, in particular, for glacier mass-balance measurements. Extensive data on snow structure need to be synthesized. Satellite imagery should be used for monitoring of seasonal snow. Snow melt during northwest storms needs to be better defined. A more developed engineering approach is required for the study of snow avalanches. New Zealand offers exciting possibilities for the study of cryospheric processes, including response to future climate change.

Description: This article presents an overview of palaeofluvial geomorphology research in southern Africa. For the purposes of this article this includes South Africa, Zimbabwe, Namibia, Lesotho, Swaziland and Botswana. Although interest in fluvial systems has a long history in southern Africa, the scientific study of rivers was initiated by the discovery of the first alluvial diamond along the banks of the Orange River in 1867. Since then, significant progress has been made in unravelling the fluvial history of southern Africa from the early Archaean Ventersdorp Contact Reef River to modern channel process studies. The development of an understanding of palaeofluvial systems has occurred along two main lines. The first was alluvial diamond exploration work undertaken by the large mining houses. The second line was of a more ‘academic’ interest and included determining the impact of superimposition, tectonics, base level and climate changes. The review suggests that southern Africa fluvial systems have shown large-scale changes in drainage pattern, discharge and sediment yield and that these can be related to a complex set of causative factors including the geological template, the Jurassic rifting of Gondwana, tectonic episodes and climate change.

Description: Sedimentological studies of coarse-grained alluvial rivers reveal patterns of bed material sorting at a variety of spatial scales ranging from downstream fining over the length of the long profile to the vertical segregation of a coarse surface layer at the scale of individual particles. This article reviews the mechanisms that sort bed material by size during sediment entrainment, transport and deposition and discusses some of the inter-relationships that exist between patterns and processes of sediment sorting at different spatial and temporal scales. At initiation of motion, sorting can arise from the preferential entrainment of the finer fractions from the heterogeneous bed sediments. Bedload grain-size distributions are modified during transport as different size fractions are routed along different transport pathways under the influence of nonuniform bed topography and associated flow patterns, and during deposition as the variable pocket geometry of the rough bed surface and turbulence intensity of the flow control the size of the particles that deposit. The review highlights the poor understanding of the many feedback linkages that exist between patterns and processes of sediment sorting at different scales and the need for a greater awareness of the spatial and temporal bounds of these linkages.

Description: Remote sensing has demonstrated wide applicability in the area of estimating and mapping forest physical and structural features. Focus in recent years has been directed towards measuring the biophysical/physiological character of forest ecosystems in order to estimate and predict forest ecosystem health and sustainability. The following reviews the relationship between forest condition and reflectance; remote-sensing measurements (and derivatives) that provide biophysical/physiological information; and the potential of hyperspectral sensors in the measurement of these parameters.

Description: This article draws attention to the potential of magnetic resonance imaging (MRI) for studies of patterns and mechanisms of water infiltration into soils, and stresses the vitally important need for collaboration between hydrologists, soil physicists and MRI experts. A brief introduction of the principles of MRI is given. This is followed by a review of the literature relating to nonpreferential infiltration, preferential infiltration exhibiting fingering and preferential infiltration involving a wide range of macropore flow. These differing degrees of complexity of infiltration dynamics require the employment of noninvasive and nondestructive techniques for their detailed investigation. Finally, an overview of applications of MRI to the detection of the spatial and temporal distribution of soil moisture and its changes is given. General conclusions are drawn from previous and current research, and the potential of the application of MRI to infiltration studies is summarized.

Description: A characteristic of beaver ecology is their ability to build dams and, thus, to modify the landscape to increase its suitability for their occupation. This ability gives beaver great significance as a geomorphic agent. In order to review the hydrogeomorphological effects of beaver dam-building activity, this article places a context on the likely distribution and magnitude of beaver activity by considering the spatial and temporal variability of distributions of beaver and the habitat characteristics which might favour the establishment of substantial beaver populations. A description is then given of the nature and potential dimensions of instream structures built by beaver and the environmental conditions under which dam building has been observed to occur. The hydrogeomorphological impact of dam building is then appraised both locally and at the landscape scale, illustrating the very significant process modification caused by beaver. While the European beaver, Castor fiber, is the main focus of this review, it necessarily draws extensively on the much larger literature concerning the North American beaver (Castor canadensis).

Description: With global periglacial geomorphology undergoing significant advancements, it is appropriate to review the past and current status of such research in Africa. A brief historical overview of research outputs and approaches is presented for the respective African regions. Potential future quantitative periglacial research needs and approaches identified for Africa include: the examination of active periglacial processes, the identification of landforms and ground-ice forms, the potential for environmental change and the palaeoenvironmental reconstruction, and the application of periglacial studies.It is demonstrated that while periglacial geomorphology has progressed significantly in southern Africa, there has been little or no advancement elsewhere on the continent over the last two decades. None the less, on a more positive note, it is concluded that Africa has considerable potential in future global periglacial research.