Comment on ‘A transport‐distance based approach to scaling erosion rates’: Parts 1, 2 and 3 by Wainwright et al.     

P. B. Hairsine  G. C. Sander 《地球表面变化过程与地形》2009,34(6):882-885

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Management alternatives to offset climate change effects on Mediterranean fire regimes in NE Spain   总被引：1，自引：0，他引：1  

Lasse Loepfe  Jordi Martinez-Vilalta  Josep Pi?ol 《Climatic change》2012,115(3-4):693-707

Fire regime is affected by climate and human settlements. In the Mediterranean, the predicted climate change is likely to exacerbate fire prone weather conditions, but the mid- to long-term impact of climate change on fire regime is not easily predictable. A negative feedback via fuel reduction, for instance, might cause a non-linear response of burned area to fire weather. Also, the number of fires escaping initial control could grow dramatically if the fire meteorology is just slightly more severe than what fire brigades are prepared for. Humans can directly influence fire regimes through ignition frequency, fire suppression and land use management. Here we use the fire regime model FIRE LADY to assess the impacts of climate change and local management options on number of fires, burned area, fraction of area burned in large fires and forest area during the twenty-first century in three regions of NE Spain. Our results show that currently fuel-humidity limited regions could suffer a drastic shift of fire regime with an up to 8 fold increase of annual burned area, due to a combination of fuel accumulation and severe fire weather, which would result in a period of unusually large fires. The impact of climate change on fire regime is predicted to be less pronounced in drier areas, with a gradual increase of burned area. Local fire prevention strategies could reduce but not totally offset climate induced changes in fire regimes. According to our model, a combination of restoring the traditional rural mosaic and classical fire prevention would be the most effective strategy, as a lower ignition frequency reduces the number of fires and the creation of agricultural fields in marginal areas reduces their extent.  相似文献   

Late Holocene tsunami traces on the western and southern coastlines of the Peloponnesus (Greece)   总被引：1，自引：0，他引：1  

Anja Scheffers  Dieter Kelletat  Andreas Vtt  Simon Matthias May  Sander Scheffers 《Earth and Planetary Science Letters》2008,269(1-2):271-279

Greece, in particular the western and southern parts close to the subduction zone of the Hellenic Trench, experiences strong earthquakes and subsequent tsunamis. Nevertheless, field evidence of tsunamis from the late Holocene is extremely rare. Our research along the coastlines of the western and southern Peloponnesus resulted in new findings of tsunami impacts in the form of clusters and ridges of large boulders and thick tsunamigenic sand layers encountered in vibracores. Many boulders contained attached marine organisms, which prove that they were transported from the foreshore environment against gravity by extreme wave events. The attached organisms, which have been dated by ¹⁴C-AMS, suggest that historical tsunami events of great energy occurred around 1300 cal AD. A wood fragment found at the base of tsunami deposits in a vibracore from Cape Punta was dated to ~ 250 cal AD.  相似文献   

Unsteady soil erosion due to rainfall impact: a model of sediment sorting on the hillslope   总被引：4，自引：0，他引：4  

P. B. Hairsine  G. C. Sander  C. W. Rose  J. -Y. Parlange  W. L. Hogarth  I. Lisle  H. Rouhipour 《Journal of Hydrology》1999,220(3-4):115-128

A new method is presented for predicting sediment sorting associated with soil erosion by raindrop impact for non-equilibrium conditions. The form of soil erosion considered is that which results from raindrop impact in the presence of shallow overland flow itself where the flow is not capable of eroding sediment. The method specifically considers early time runoff and erosion when sediment leaving an eroding area is generally finer and thus may have a higher potential for transport of sorbed pollutants. The new mechanism described is the formation of a deposited layer on the soil surface, which is shown to lead to sediment sorting during an erosion event. The deposited layer is taken to have two roles in this process: to temporarily store sediment on the surface between successive trajectories, and to shield the underlying soil from erosive stresses. Equations describing the dynamics of the suspended sediment mixture and the deposited layer are developed. By integrating these equations over the length of eroding land element and over the duration of the erosion event, an event-based solution is proposed which predicts total sediment sorting over the event. This solution is shown to be consistent with experimentally observed trends in enrichment of fine sediment. Predictions using this approach are found to only partly explain measured enrichment for sets of experimental data for two quite different soils, but to be in poor agreement for an aridsol of dispersive character. It is concluded that the formation of the deposited layer is a significant mechanism in the enrichment of fine sediment and associated sorbed pollutants, but that processes in the dispersive soil are not as well described by the theory presented.  相似文献   

Lake evolution in a semi-arid montane environment: response to catchment change and hydroclimatic variation     

Henry Lamb  Neil Roberts  Melanie Leng  Philip Barker  Abdelfattah Benkaddour  Sander van der Kaars 《Journal of Paleolimnology》1999,21(3):325-343

Pollen, geochemical and sedimentological data from Sidi Ali, a montane Moroccan lake, provide a 7000 yr record of changes in climate, catchment vegetation and soil erosion intensity. Diatoms, non-silicious algae, macrophyte fossils and ostracods from the same core record the dynamics of the lake ecosystem. Oxygen isotope and trace-element ratios of benthic ostracods appear to be relatively insensitive to climatic variation in this open lake with low water-residence time, but diatom plankton / periphyton (P/L) ratios show lake-level variations that are probably climate controlled. At least two superimposed processes are recorded, but at different timescales: catchment vegetation and soils show long-term changes due to climate and human impact, whereas P/L ratios suggest century-scale oscillations in lake depth. The timing of changes in algal and macrophyte productivity and carbon cycling within the lake broadly corresponds to changes in terrestrial vegetation, suggesting either that lake nutrient status is linked to catchment vegetation and soils, or that both were influenced by climate. The lack of a sensitive and independent (non-biological) climate proxy makes it more difficult to assess the lake's ecological response to short-term climate variation. Overall, the lake's evolution has been influenced both by catchment-mediated nutrient flux and by changes in water balance, thus having characteristics in common with both temperate and arid zone lakes.  相似文献   

Mariner 9—Image processing and products     

E.C. Levinthal  W.B. Green  J.A. Cutts  E.D. Jahelka  R.A. Johansen  M.J. Sander  J.B. Seidman  A.T. Young  L.A. Soderblom 《Icarus》1973,18(1):75-101

The purpose of this paper is to describe the system for the display, processing, and production of image-data products created to support the Mariner 9 Television Experiment. Of necessity, the system was large in order to respond to the needs of a large team of scientists with a broad scope of experimental objectives. The desire to generate processed data products as rapidly as possible to take advantage of adaptive planning during the mission, coupled with the complexities introduced by the nature of the vidicon camera, greatly increased the scale of the ground-image processing effort.This paper describes the systems that carried out the processes and delivered the products necessary for real-time and near-real-time analyses. References are made to the computer algorithms used for the, different levels of decalibration and analysis.  相似文献   

Reply to Comment on: Coarse clast ridge sequences as suitable archives for past storm events? Case study on the Houtman Abrolhos,Western Australia     

Anja M. Scheffers  Sander R. Scheffers  Dieter H. Kelletat  Peter Squire  Lindsay Collins  Yuexing Feng  Jian‐Xin Zhao  Renaud Joannes‐Boyau  Simon Matthias May  Gerhard Schellmann  Heather Freeman 《第四纪科学杂志》2013,28(2):213-215

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Startle response of captive North Sea fish species to underwater tones between 0.1 and 64 kHz     

Kastelein RA  Heul Sv  Verboom WC  Jennings N  Veen Jv  de Haan D 《Marine environmental research》2008,65(5):369-377

World-wide, underwater background noise levels are increasing due to anthropogenic activities. Little is known about the effects of anthropogenic noise on marine fish, and information is needed to predict any negative effects. Behavioural startle response thresholds were determined for eight marine fish species, held in a large tank, to tones of 0.1-64 kHz. Response threshold levels varied per frequency within and between species. For sea bass, the 50% reaction threshold occurred for signals of 0.1-0.7 kHz, for thicklip mullet 0.4-0.7 kHz, for pout 0.1-0.25 kHz, for horse mackerel 0.1-2 kHz and for Atlantic herring 4 kHz. For cod, pollack and eel, no 50% reaction thresholds were reached. Reaction threshold levels increased from approximately 100 dB (re 1 microPa, rms) at 0.1 kHz to approximately 160 dB at 0.7 kHz. The 50% reaction thresholds did not run parallel to the hearing curves. This shows that fish species react very differently to sound, and that generalisations about the effects of sound on fish should be made with care. As well as on the spectrum and level of anthropogenic sounds, the reactions of fish probably depend on the context (e.g. location, temperature, physiological state, age, body size, and school size).  相似文献   

A 100 000‐year record of annual and seasonal rainfall and temperature for northwestern Australia based on a pollen record obtained offshore     

Sander van der Kaars  Patrick De Deckker  Franz X. Gingele 《第四纪科学杂志》2006,21(8):879-889

Pollen recovered from core tops of deep‐sea cores from offshore northwestern Western Australia were used to build climatic transfer functions applied to sediment samples from major rivers bordering the ocean in the same region and a deep‐sea core offshore Northwest Cape. Results show for the last 100 000 years, with a gap in the record spanning the 64 000 to 46 000 years interval, that from about 100 000 to 82 000 yr BP, climatic conditions represented by rainfall, temperature and number of humid months, were significantly higher than today's values. For the entire record, the coldest period occurred about 43 000 to 39 000 yr BP but it was wetter than today, whereas the Last Glacial Maximum saw a significant reduction in summer rainfall, interpreted as a result of the absence of monsoonal activity in the region. The Holocene can be divided into two distinct phases: one peaking around 6000 cal. yr BP with highest rainfall and summer temperatures; the second one commencing at 5000 cal. yr BP and showing a progressive decrease in summer rainfall in contrast to an increase in winter rainfall, paralleled by a progressive decrease in temperatures. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

How to communicate the scientific consensus on climate change: plain facts,pie charts or metaphors?     

Sander L. van der Linden  Anthony A. Leiserowitz  Geoffrey D. Feinberg  Edward W. Maibach 《Climatic change》2014,126(1-2):255-262

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