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411.
Glacial retreat and the thawing of permafrost due to climate warming have altered the hydrological cycle in cryospheric‐dominated watersheds. In this study, we analysed the impacts of climate change on the water budget for the upstream of the Shule River Basin on the northeast Tibetan Plateau. The results showed that temperature and precipitation increased significantly during 1957–2010 in the study area. The hydrological cycle in the study area has intensified and accelerated under recent climate change. The average increasing rate of discharge in the upstream of the Shule River Basin was 7.9 × 106 m3/year during 1957–2010. As the mean annual glacier mass balance lost ?62.4 mm/year, the impact of glacier discharge on river flow has increased, especially after the 2000s. The contribution of glacier melt to discharge was approximately 187.99 × 108 m3 or 33.4% of the total discharge over the study period. The results suggested that the impact of warming overcome the effect of precipitation increase on run‐off increase during the study period. The evapotranspiration (ET) increased during 1957–2010 with a rate of 13.4 mm/10 years. On the basis of water balance and the Gravity Recovery and Climate Experiment and the Global Land Data Assimilation System data, the total water storage change showed a decreasing trend, whereas groundwater increased dramatically after 2006. As permafrost has degraded under climate warming, surface water can infiltrate deep into the ground, thus changing both the watershed storage and the mechanisms of discharge generation. Both the change in terrestrial water storage and changes in groundwater have had a strong control on surface discharge in the upstream of the Shule River Basin. Future trends in run‐off are forecasted based on climate scenarios. It is suggested that the impact of warming will overcome the effect of precipitation increase on run‐off in the study area. Further studies such as this will improve understanding of water balance in cold high‐elevation regions. 相似文献
412.
Summary It is widely accepted that the nature and extent of commuting patterns worldwide represent a large slice of the overall environmental problems associated with transport use. There has been a long-standing concern over the 'congestion peaks' derived from daily travel-to-work patterns, and a preoccupation with the ways in which greener modes of commuting might contribute to a more environmentally benign transport system. This article uses Census data to focus on commuting patterns in England and Wales, concluding that, despite recent moves towards promoting a more integrated and sustainable transport system, worrying trends persist that would seem to undermine this strategy. On a more positive note, the Census data also suggest that many shorter trips might potentially be converted to 'greener modes' walking or cycling–with substantial environmental benefits. 相似文献
413.
Nick R. Varley Raúl Arámbula-Mendoza Gabriel Reyes-Dávila John Stevenson Rob Harwood 《Bulletin of Volcanology》2010,72(9):1093-1107
During the period from February to September 2005, Volcán de Colima produced 30 Vulcanian explosions of sufficient magnitude
to produce pyroclastic flows of variable size, with a total volume of at least 2.5 × 106 m3. Swarms of long-period events were associated with each event, their duration ranging from about 6 h to 3 days and each swarm
containing up to 886 events. The characteristics of the swarms have been studied to understand the source mechanism and their
relationship with the Vulcanian explosions. In total, 12,548 long-period events were analysed using various comparative and
statistical methods. Patterns were not apparent in the data with no correlation between different properties of the swarms
(duration, magnitude or frequency of occurrence of LP events) and the magnitude of the associated Vulcanian explosion, whether
recorded by seismicity, volume of pyroclastics or altitude of the eruption column. This, along with other characteristics
of the swarms, such as the continuation of the swarm after the explosion, with an increase in long-period event amplitude
in some cases, suggests that the mechanism is not merely associated with the pressurization under an impermeable cap and resulting
pressure differentials between adjacent volumes within the system. It is more likely that the production of long-period events
is dominated by brittle fracturing on the margins of an ascending magma body. A model is proposed whereby the unloading above
the ascending magma column produced by a Vulcanian explosion resulted in an increase in ascent rate, reflected in the increasing
amplitude of long-period events. The results reflect the complexity of non-linear processes involved during magma ascent,
degassing, crystallization and rupture of the impermeable plug during the Vulcanian process. At Volcán de Colima, as at many
volcanoes, long-period events represent a useful precursor for eruptive activity. For monitoring, this paper highlights some
useful analyses that can be carried out, which could illustrate certain characteristics of an eruptive episode. A preliminary
model is presented of the conduit processes at work during the cyclic extrusive and explosive activity during 2005. 相似文献
414.
Rachel Bynoe Nick M. Ashton Tim Grimmer Peter Hoare Joanne Leonard Simon G. Lewis Darren Nicholas Simon Parfitt 《第四纪科学杂志》2021,36(2):191-210
Recent archaeological discoveries from exposures of the Cromer Forest-bed Formation at Happisburgh, UK, have radically changed interpretations of the nature and timing of early hominin occupation of northern latitudes, but this in situ archaeology is only one part of the picture. Surface finds of Pleistocene mammalian remains have been found along this coastline for centuries, with stone tools adding to this record over the past 7 years. The ex situ nature of these finds, however, means they are often seen as limited in the information they can provide. This work contributes to a growing body of research from a range of landscape and environmental contexts that seeks to demonstrate the value and importance of these ex situ assemblages. Here the focus is on Palaeolithic flint artefacts and Pleistocene mammalian remains recovered by a group of local collectors through systematic, GPS-recorded beach collection from 2013 to 2017, and their use in developing a methodology for working with ex situ Palaeolithic finds in coastal locations. The results demonstrate significant patterning that identifies unexplored exposures both onshore and offshore, considerably expanding the known extent of deposits and facilitating new insights into the wider archaeological landscape associated with the earliest occupation of northern Europe. 相似文献
415.
The lithic record from the Solent River and its tributaries is re‐examined in the light of recent interpretations about the changing demography of Britain during the Lower and early Middle Palaeolithic. Existing models of the terrace stratigraphies in the Solent and its tributary areas are reviewed and the corresponding archaeological record (specifically handaxes) for each terrace is assessed to provide models for the relative changes in human occupation through time. The Bournemouth area is studied in detail to examine the effects of quarrying and urbanisation on collection history and on the biases it introduces to the record. In addition, the effects of reworking of artefacts from higher into lower terraces are assessed, and shown to be a significant problem. Although there is very little absolute dating available for the Solent area, a cautious interpretation of the results from these analyses would suggest a pre‐Marine Isotope Stage (MIS) 12 date for the first appearance of humans, a peak in population between MIS 12 and 10, and a decline in population during MIS 9 and 8. Owing to poor contextual data and small sample sizes, it is not clear when Levallois technology was introduced. This record is compared and contrasted to that from the Thames Valley. It is suggested that changes in the palaeogeography of Britain, in particular land connections to the continent, might have contributed to differences in the archaeological records from the Solent and Thames regions. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
416.