late holocene erosion in upland britain climatic deterioration or human influence the evidence for enhanced erosion in upland britain during the late holocene is evaluated though there is widespread evidence for recent soil erosion on high plateaux this has not been precisely dated radiocarbon dating confirms the occurrence of late holocene solifluction on high ground but at only one site has evidence been found for recent accelerated activity several areas however have yielded evidence of late holocene debris cone accumulation and parts of the scottish highlands experienced a drastic increase in debris flow activity over the past few centuries climatic deterioration and vegetation degradation resulting from overgrazing or burning are frequently cited as the causes of enhanced erosion but cause and effect are often related only by coincidence of timing in consequence only circumstantial evidence links erosion with climatic deterioration though anthropogenic influences have been more firmly established at a few sites the role of extreme events in initiating phases of uplan

modelling differential catchment response to environmental change the caesar cellular automaton evolutionary slope and river model is used to demonstrate significant differences in coarse sediment transfer and alluviation in medium sized catchments when responding to identical holocene environmental changes simulations for four u k basins the rivers swale ure nidd and wharfe shows that catchment response driven by climate and conditioned by land cover changes is synchronous but varies in magnitude there are bursts of sediment transfer activity generally of rapid removal but with some sediment accumulation dspikest with longer periods of slow removal or accumulation of sediment in different valley reaches within catchments reach sensitivity to environmental change varies considerably some periods are only recorded in some reaches whilst higher potential sensitivity typically occurs in the piedmont areas of the catchments modelled here these differential responses appear to be highly non linear and may relate to the passage of sediment waves by variable local sediment storage and availability and by large and small scale thresholds for sediment transfer within each catchment differential response has major implications for modelling fluvial systems and the interpretation of field data model results are compared with the record of dated alluvial deposits in the modelled catchments d 2005 elsevier b v all rights reserved

quantitative assessment of landform equifinality and palaeoenvironmental reconstruction using geomorphic models abstract we present results from a study of post glacial alluvial fan evolution in new zealand in which a series of 83 000 numerical simulations of fan formation were conducted within a monte carlo framework in order to evaluate the potential for reconstructing past environmental conditions by matching simulated and observed fan morphologies our results indicate that simulations based on a wide range of model boundary conditions and internal process parameterisations are able to reproduce the observed fan characteristics such equifinal behaviour is a product of an imposed limit on fan progradation and associated autogenic feedbacks which drive fan entrenchment even in the absence of external changes in water or sediment supply we find little evidence that the majority of preserved fan terraces that formed post entrenchment did so during periods of higher than average discharge or sediment supply to the fan apex or that evidence for significant changes in sediment supply associated with major climate shifts are likely to be preserved in the current fan morphology these results illustrate the difficulties that are inherent in the interpretation of alluvial landforms as records of past environmental conditions they also highlight the need for more rigorous quantification of uncertainties in field and model based interpretation of landscape responses to environmental change

preservation potential for late quaternary river alluvium valley sequences of late quaternary alluvial units reflect alluvial preservation as well as alluvial production factors effects of lateral channel migration incision aggradation and channel stability on preservation potential are explored and then considered in the light of 14 available data sets cartographically dated and model data based on lateral channel migration well mapped and dated late quaternary valley unit surveys and composite age frequency plots for dated alluvial units and flood sediments despite much expectable variation between sites and the complex effects of river activity combinations a common characteristic of the data sets examined is the significance of preservation factors lateral migration tends to eliminate older units as it creates new alluvial deposits whereas incision may lead to the preferential preservation of older units beyond the incision slot aggradational environments are likely to preserve more complete records although simultaneous lateral migration may eliminate possibly repeatedly the upper parts of alluvial units the common pattern of inset and incised streams within pleistocene and early holocene fills or bedrock gives finite extent to later units within narrowing valleys so that development of new valley floor units is necessarily at the expense of reprocessing earlier ones floods associated with both slack water deposits and berms are also responsible for the removal of accessible earlier materials thus limiting the preserved record of earlier events in light of these censoring effects of river activities the sequence of preserved late quaternary units within uk sequences is reconsidered it is concluded that preservation potential factors have led to spatial and temporal bias in the alluvial record and that both here and elsewhere preservation potential needs to be considered systematically alongside variable sedimentation resulting from allogenic environmental factors when interpreting the alluvial archive copyright 2003 john wiley sons ltd journal of quaternary science

a major widespread climatic change around 5300 cal yr bp at the time of the alpine iceman palaeoenvironmental and archaeological data from arbon bleiche lake constance switzerland give evidence of a rapid rise in lake level dated by tree ring and radiocarbon to 5320 cal yr bp this rise event was the latest in a series of three successive episodes of higher lake level between 5550 and 5300 cal yr bp coinciding with glacier advance and tree limit decline in the alps this west central european climate change may have favoured the quick burial and the preservation of the alpine iceman recently found in the tyrolean alps it has possible equivalents in many records from various regions in both hemispheres dating to 5600 5000 cal yr bp and corresponds to global cooling and contrasting patterns of hydrological changes this major mid holocene climate event marks the hypsithermal neoglaciation transition possibly resulting from a combination of different factors including orbital forcing changes in ocean circulation and variations in solar activity copyright 2004 john wiley sons ltd

long term development of holocene and pleistocene gullies in the protva river basin central russia abstract the specific geomorphic structure a combination of flat or gentle watersheds with short steep valley sides and the high resistance of surface material in the case study area in the centre of the russian plain are responsible for the specific pattern of holocene erosion no or minor sheet erosion the occasional appearance of new gullies on the valley sides four out of 19 studied and a concentration of erosion activity in old gullies that had existed since pre holocene times 15 out of 19 studied the erosion activity is studied using radiocarbon dating of gully sediments summed probability density distribution spdd of 65 radiocarbon dates is applied to detect changes of erosion rates over the last five millennia three millennium scale phases of erosion activity are distinguished phase 1 1200 years bp to the present intensive erosion phase 2 2800 to 1200 years bp weak erosion and phase 3 4800 to 2800 years bp intensive erosion short episodes or single events of relatively strong erosion have been found at around 4700 3800 3000 2200 1800 and 900 years bp erosion during phase 3 coincided with the holocene lowest population density in the whole region and the start of phase 1 coincided with a population gap at the case study area which suggests other than anthropogenic causes for changing erosion regimes these may be climatic factors because changes between millennium scale phases of erosion activity coincide with pronounced climatic changes the subboreal subatlantic transition and the start of the medieval warm period however a direct correlation between erosion activity and climatic parameters warmer cooler wetter drier has not been found presumably because the available palaeoclimatic reconstructions do not contain enough information on changing frequencies and magnitudes of hydrological extremes according to population dynamics charcoal frequency in erosion derived sediments and pollen data a human impact on erosion is suggested to have occurred from the 11th century ad and more confidently from the 14th 16th centuries this contributed to erosion acceleration that began some two centuries earlier apparently for climatic reasons

persistent solar influence on north atlantic climate during the holocene surface winds and surface ocean hydrography in the subpolar north atlantic appear to have been influenced by variations in solar output through the entire holocene the evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon 14 and beryllium 10 and centennial to millennial time scale changes in proxies of drift ice measured in deep sea sediment cores a solar forcing mechanism therefore may underlie at least the holocene segment of the north atlantic9s 1500 year cycle the surface hydrographic changes may have affected production of north atlantic deep water potentially providing an additional mechanism for amplifying the solar signals and transmitting them globally

contrasting patterns of hydrological changes in europe in response to holocene climate cooling phases the quantitative reconstruction of climatic parameters from pollen and lake level data obtained at saint jorioz lake annecy eastern france gives evidence for cooler and wetter conditions during the 8 2 ka cold event a comparison of these regional data with other hydrological records reconstructed in europe for the same period suggests as a working hypothesis that mid latitudes between ca 50 and 43 underwent wetter conditions in response to the cooling whereas northern and southern europe were marked by drier climate in the latter case leading to an interruption of the sapropel 1 formation in the mediterranean a similar hydrological tri partition of europe can be observed during other holocene cooling phases associated with north atlantic ird events data indicate that the middle zone characterised by wetter climate conditions could have had a more extended latitudinal amplitude during phases of climate cooling weaker than the 8 2 ka event the differences in expansion of the wet mid european zone depending on holocene climate cooling phases could reflect variations in the strength of the atlantic westerly jet in relation with the thermal gradient between high and low latitudes

numerical study on the interaction among a nonlinear wave composite breakwater and sandy seabed most previous investigations related to composite breakwaters have focused on the wave forces acting on the structure itself from a hydrodynamic aspect the foundational aspects of a composite breakwater under wave induced cyclic loading are also important in studying the stability of a composite breakwater in this study numerical simulations were performed to investigate the wave induced pore water pressure and flow changes inside the rubble mound of the composite breakwater and seabed foundation the validity and applicability of the numerical model were demonstrated by comparing numerical results with existing experimental data moreover the present model clearly has shown that the instantaneous directions of pore water flow motion inside the seabed induced by surface waves are in good agreement with the general wave induced pore water flow inside the seabed the model is further used to discuss the stability of a composite breakwater i e the interaction among nonlinear waves composite breakwater and seabed numerical results suggest that the stability of a composite breakwater is affected by not only downward shear flow generating on the seaward slope face of the rubble mound but also a high and dense pore water pressure gradient inside the rubble mound and seabed foundation

paleoenvironmental and geoarchaeological reconstruction from late holocene slope records lower huerva valley ebro basin ne spain abstract slope deposits in semiarid regions are known to be very sensitive environments especially those that occurred during the minor fluctuations of the late holocene in this paper we analyse holocene colluvium genesis composition and paleoenvironmental meaning through the study of slope deposits in ne spain two cumulative slope stages are described during this period in the study area both slope accumulations are superimposed and this has enabled an excellent preservation of the aggregative sequence and the paleosols corresponding to stabilisation stages 14c and tl dating as well as archaeological remains provide considerable chronological precision for this sequence the origin of the accumulation of the lower unit is placed around 4295 4083 cal yr bp 2346 2134 cal yr bc late chalcolithic and it developed until the iron age in a cooler and wetter climate cold iron age under favourable conditions a soil a horizon was formed on top of this unit a new slope accumulation was formed during the little ice age within the slope two morphogenetic periods ending with a horizons are distinguished and related with two main cold wet climatic events the study of these slopes provides a great amount of data for the paleoenvironmental and geoarchaeological reconstruction of the late holocene in ne spain

dating of post glacial landforms in the central howgills little is known of holocene landform development in upland britain this paper describes a site at middle langdale in the howgill fells of cumbria where large but now stabilized and inactive gullies cut through periglacial material at the base of the gullies large debris cones have buried earlier alluvial sediments on the valley floor on these sediments and buried by the debris cones is a well developed organic soil from which two 14c dates have been obtained in an attempt to estimate the age range of the soil these dates range from 2580 55 years bp for the fine particulate fraction from the base of the organic horizon to 940 95 years bp for fossil rootlets from the uppermost organic layer immediately below the overlying debris cones the pollen evidence suggests that the valley floor site was initially dominated by alder carr and later by a juncus marsh with birch alder and hazel nearby the pollen from the surrounding upland area suggests woodland on the valley sides dominated by oak and elm that was later replaced by a more open environment rich in heath species and in which disturbed ground species were present the magnetic evidence indicates a stable local environment during soil formation but shows a sudden inwash of unweathered debris at the top of the buried soil the evidence suggests that the valley floor was geomorphologically stable throughout the period of soil formation although there was a local change in valley floor vegetation and a reduction of woodland cover on the valley sides at sometime during the period the evidence then points to major geomorphological changes a wave of soil erosion gully development and debris cone deposition perhaps following the scandinavian introduction of sheep farming in the tenth century a d

late holocene fluvial chronology of spain the role of climatic variability and human impact abstract a database of published and unpublished radiocarbon dates from late holocene fluvial environments in spain was critically analysed in order to obtain a fluvial chronology for this period the principal types of depositional environment represented in the record were slackwater flood deposits 28 dates alluvial overbank facies 12 dates and alluvial channel facies 7 dates the sedimentary context of each date was classified in order to identify those samples that specifically dated change in the fluvial environment analysis of the different depositional environment data sets using summed probability plots identified phases of alluviation at 2800 2350 and 800 500 cal bp increased frequency of large magnitude floods occurred at 2850 2500 1000 800 and 520 250 cal bp the results indicate that in mediterranean regions slackwater flood deposits are valuable archives of climatic variability even during periods of increased human impact

holocene alluviation and hydrology in the upper thames basin a sequence of changing conditions for flooding and alluviation in the upper thames valley during the holocene has been identified and provisionally dated by the investigation of archaeological sites interstratified with alluvium archaeological survey suggests that the changes can be related to clearance and agricultural activity in the catchment area

holocene climatic instability a prominent widespread event 8200 yr ago the most prominent holocene climatic event in greenland ice core proxies with approximately half the amplitude of the younger dryas occurred 8000 to 8400 yr ago this holocene event affected regions well beyond the north atlantic basin as shown by synchronous increases in windblown chemical indicators together with a significant decrease in methane widespread proxy records from the tropics to the north polar regions show a short lived cool dry or windy event of similar age the spatial pattern of terrestrial and marine changes is similar to that of the younger dryas event suggesting a role for north atlantic thermohaline circulation possible forcings identified thus far for this holocene event are small consistent with recent model results indicating high sensitivity and strong linkages in the climatic system

palaeoflood record of the tagus river central spain during the late pleistocene and holocene abstract palaeoflood hydrology of the tagus river central spain was reconstructed from slackwater deposits and palaeostage indicators in two canyon reaches located at el puente del arzobispo in the central part of the catchment 35 000 km 2 in drainage area and in alcantara at the lower part of the catchment 52 000 km 2 in drainage area near the portuguese border the palaeoflood record with more than 80 flood events shows clusters of floods at specific periods from 9440 to 9210 14 c yr bp 8540 8110 bc 8500 to 8000 14 c yr bp 7500 7000 bc 6750 14 c yr bp 5000 bc 1200 to 950 14 c yr bp ad 785 1205 410 14 c yr bp ad 1450 1500 170 to 80 14 c yr bp ad 1670 1950 the largest flood s occurred during the periods 9440 to 9210 14 c yr bp 6750 14 c yr bp and 1200 to 950 14 c yr bp reaching minimum discharge estimates of between 4000 and 4100 m 3 s 1 in the el puente del arzobispo reach and 13 700 15 000 m 3 s 1 in the alcantara reach these periods with increased flood magnitude and or frequency in the tagus river are strongly related to increased moisture influx and winter precipitation in the iberian peninsula especially in the western zone proxy records sensitive to winter precipitation such as lake levels and vegetation changes indicated by pollen records are in good agreement with the clusters of floods found in the tagus river this flood variability seems to correspond to changes in the prevailing atmospheric circulation pattern affecting the iberian peninsula

the development and application of a database of radiocarbon dated holocene fluvial deposits in great britain abstract this paper reports on the development of a british database of 14c dated holocene fluvial units over the last 15 years since its inception in 1989 the database has undergone substantial expansion refinement and improvement together with considerable methodological development so that today it serves as a powerful research tool for investigating the spatial and temporal dynamics of holocene river development and flooding in great britain the improved analytical method is here applied to the currently existing database by examining datasets of 14c dated fluvial units from river basins that lie within and beyond the limits of late devensian glaciation this analysis indicates how the contrasted conditions in these two types of river environment have to an extent led to divergent records of flooding in response to holocene climate and land use change however even in the contrasting sedimentary records of upland glaciated and lowland unglaciated river basins six corresponding episodes of increased flood frequency are identified at c 5730 c 3540 c 2730 c 2280 c 660 and c 570 cal bp these represent widespread common responses from british river systems to large scale changes in climate the method of database construction and analysis outlined and demonstrated in this paper could be readily adopted in other parts of the world to improve our understanding of holocene river behaviour at the continental and global scale

late quaternary alluviation and soil formation in the southern argolid its history causes and archaeological implications in the context of an archaeological survey of the southern argolid greece studies have been carried out to elucidate the evolution of the landscape since its earliest known human occupation about 50 000 years ago one of these studies was a detailed geological mapping of the late quaternary alluvium and soils in the area dated by means of thorium uranium disequilibria archaeological finds and historical information seven periods of alluviation were identified each of short duration relative to long intervening periods of stability and soil formation the three earliest alluvial phases falling before and during the last glacial interval range from about 330 000 to 32 000 years in age no alluviation accompanied the last glacial maximum around 20 000 years ago in fact a stable landscape persisted until about 4500 years ago when debris flows and widespread aggradation in the valleys resulted from major slope destabilization and soil erosion probably as a result of extensive land clearance in the early bronze age a subsequent stable period lasted through the many upheavals of the later bronze age the dark ages and the early historical period it came to an end with a brief phase of alluviation between about 300 and 50 bc stability returned through the late roman period notwithstanding considerable expansion of the settled area another period of destabilization this one marked by debris flows and hence major soil erosion is poorly fixed in time but probably coincides with expanded maquis clearance accompanying the resettlement of the area around ad 1000 subsequent events of soil erosion and aggradation vary in nature and timing from one drainage to the next and in some areas continue today nature and chronology of the soil forming and alluviation events show that simple correlations with climatic events do not suffice to explain them for the latter ones past about 2500 bc human activity seems to be the dominant cause but once again the relation between cause and effect is not straightforward land clearing or neglect of soil conservation efforts during economic downturns appear to have a more devastating effect upon the landscape than do intensive land use or total land abandonment

turbulent mixing in a deep fracture zone on the mid atlantic ridge abstractmidocean ridge fracture zones channel bottom waters in the eastern brazil basin in regions of intensified deep mixing the mechanisms responsible for the deep turbulent mixing inside the numerous midocean fracture zones whether affected by the local or the nonlocal canyon topography are still subject to debate to discriminate those mechanisms and to discern the canyon mean flow two moorings sampled a deep canyon over and away from a sill contraction a 2 layer exchange flow accelerated at the sill transports 0 04 0 10 sv 1 sv 106 m3 s 1 up canyon in the deep layer at the sill the dissipation rate of turbulent kinetic energy e increases as measured from microstructure profilers and as inferred from a parameterization of vertical kinetic energy cross sill density and microstructure transects reveal an overflow potentially hydraulically controlled and modulated by fortnightly tides during spring to neap tides e varies from o 10 9 to o 10 10 w kg 1 below 3500 m around the 2 layer inte

interpreting alluvial archives sedimentological factors in the british holocene fluvial record abstract a holocene alluvial archive of 506 dated units for great britain is analysed in terms of the sedimentation styles involved the database is classified by sedimentation unit channel sediments palaeochannel fills floodplain surface sediments floodbasins and colluvial deposits and alluvial ensemble fans and cones upland gullies and streams braided systems and active inactive meandering and anastomosing systems floodplain palaeochannel and floodbasin sediments dominate the record mostly from meandering anastomosing systems different sediment units show varied potential for recording environmental change some are relatively poorly dated with respect to the volumes of material involved whilst many dates float in periods of depositional activity which lasted for extended time periods much dated activity is autogenic and of relatively little value in interpreting external environmental influence ensembles and units are similar in age patterns in some respects commonly they exhibit sets of short term peaks in sedimentation activity but differ in others floodbasins and to an extent braided systems feature in the earlier holocene whilst dated fan deposition is more evident in the late holocene there is a general bias towards sediment units of late holocene age which probably reflects preservation factors previous british holocene alluviation models are reviewed it is suggested that the majority of earlier models reflect partial views imposed by limited regional coverage and available dating

anthropogenic and climatic impact on holocene sediment dynamics in se spain a review the climatic and anthropogenic control on holocene sediment dynamics was not well constrained for the western mediterranean basin the paucity of high resolution palaeoenvironmental records long hampered a detailed understanding of the human impact on erosion rates this paper analyses holocene sediment dynamics in the context of regional climatic conditions land cover and human occupation based on an extended compilation of recently published high resolution paleoenvironmental proxy data from both terrestrial and marine environments the palaeoenvironmental reconstruction identified four main aridification episodes a at 5600 4700 a4 4100 3400 a3 2800 2500 a2 and 1900 1300 1200 a1 cal bp most of the severe aridification phases were climatically induced not human driven and well correlated with a large dataset of paleoenvironmental records from the western mediterranean basin and north atlantic ocean the phases of enhanced aridity are generally associated with enhanced sediment dynamics independent of the intensity and type of human occupation in contrast wet climatic conditions are found to be associated with both high and low sediment dynamics dependent on the human impact on the environment the mid late phoenician phoenician ii republican rome civilizations and the christian reconquest are all associated with high human impact on the environment and high erosion rates are reported for the vera basin and ne spain despite the improved hydrological conditions human occupation is not necessarily associated with geomorphic instability as shown by the post argaric omeya and nazarene periods that are characterized by low erosion rates and geomorphic stability

interpreting drivers of change in fluvial archives of the western mediterranean a critical view abstract fluvial archives in particular late glacial to holocene floodplain records may provide valuable information regarding past environmental conditions and stages of landscape evolution in view of the high significance of floodplain dynamics for the development of entire landscapes the number of studies that have been performed on floodplain sediments remains comparatively low especially regarding the western mediterranean region however one of the reasons could be seen in the high complexity and diversity of processes and factors that control and influence fluvial activity that often hampers a straightforward interpretation of floodplain dynamics therefore a basic demand on fluvial archive research is to address the complexity of the factors that control the characteristics of fluvial sequences in order to provide a robust basis for their interpretation as a starting point for discussion this paper aims to give an overview of fluvial dynamic patterns in the western mediterranean for the last 15 ka in order to examine their relevance for palaeoenvironmental reconstructions the basis for this is provided by previous investigations on four different river systems in spain and northern africa the results of which are herein synthesized in order to propose a regional late pleistocene and holocene fluvial history for the western mediterranean realm basic results are related to alluvial floodplain deposits and visible features within them such as alluvial soils incision marks and aggradation phenomena since fluvial systems are open systems we discuss our findings against the background of different influencing factors that could modify fluvial architecture and may restrict palaeoenvironmental reconstructions a more comprehensive interpretation focuses on signals that are common to each of the studied river systems in this respect we critically discuss the customary nature of cumulative probability functions for the identification of regional flooding episodes and point out the benefits of a stratigraphy supported approach for characterizing regional floodplain dynamics finally three alluvial soil formation periods were found in all settings a first phase after 15 ka ending with the younger dryas event a second one from 7 to 5 ka with a break between 6 5 and 5 5 ka and a third phase between 3 and 2 ka these soil formation periods were interrupted and framed by fluvial dynamic phases accompanied by channel aggradation floodplain deposition floodplain erosion and or river incision in particular after 5 ka around 1 6 and at 1 ka and during the little ice age lia floodplain aggradation affected river systems in iberia and northern africa as well a cautious assessment of these results and extensive comparisons with secondary archive information prompts us to relate the aggradation periods with climate forcing by means of a supra regional aridification that effected large areas of the western mediterranean in contrast the three mentioned soil formation periods can be linked with landscape stability most probably triggered by favorable climate conditions in the western mediterranean apart from these large scale patterns we discuss the reliability of information emerging from floodplain records against the background of individualistic river behavior and self organization regarding future work we want to emphasize the great potential of yet rarely applied system oriented approaches that also attach importance to sub catchment dynamics as a link between catchment slopes and the main river floodplain

terraced fills of pleistocene and holocene age in the rheidol valley wales the legacy of repeated pleistocene glaciations has endowed many welsh river valleys with locally thick successions of glacial and alluvial sediments investigations of a well preserved flight of terraced sediments with good exposures at capel bangor on the afon rheidol mid wales has allowed its quaternary valley fill stratigraphy to be examined in detail study has revealed five terraced fills consisting of seven distinct sedimentary units these range from late devensian ice contact and ice marginal deposits to holocene high sinuosity stream sediments with episodes of man induced accelerated deposition of fine grained alluvium and to aggradation and subsequent incision associated with historic metal mining examination of general sedimentary properties e g granulometry sedimentary structures terrace surface morphology show both differences in the pattern and controls of deposition and also progressive changes over late devensian and holocene times the sediments of the rheidol valley record the response and subsequent recovery of a drainage basin to glaciation and the increasing influence of man on sediment yields channel processes and sediment quality

late holocene paleoecology and sedimentary history of a small lowland catchment in central england a variety of paleoecological and sedimentary techniques were used to investigate the storage of sediment within a small lowland catchment during the holocene radiocarbon dating of vertically accreted floodplain deposits allowed the calculation of inorganic accumulation rates these rates show a dramatic increase in sediment deposition during the late bronze age and early iron age 2900 2300 yr b p due to deforestation and cultivation of the catchment slopes and resultant soil erosion the soils within the catchment were susceptible to structural damage surface waterlogging and slope wash erosion from the calculated increases in sediment storage estimates of catchment erosion were made which vary from around 20 to 140 tons km 2 yr 1 the study of alluvial chronology at this scale can provide unique information on the source areas of holocene floodplain sediments and provide long term erosion rates

centennial to millennial scale holocene climate deep water linkage in the north atlantic the stability of the earth s climate is strongly linked to the steadiness of the atmospheric and oceanic transport of heat from low to high latitudes high resolution holocene sedimentary records from the subpolar north atlantic demonstrate a persistent link between centennial to millennial scale fluctuations in the flow speed of iceland scotland overflow water inferred from granulometric proxy data and both the surface north atlantic current component of the meridional overturning circulation moc and published fennoscandian atmospheric temperature variability however these data also highlight the difficulties associated with the interpretation of geochemical and sedimentological deep water circulation proxies as they do not provide a wholly consistent picture the similarity between surface and deep ocean 13c records suggests a preformed component in the deep ocean 13c signal on the other hand the sedimentological results display a strong linkage to changing conditions in the overlying surface ocean waters suggesting this proxy better reflects the activity of the moc at least during the holocene of this region the most widespread oceanic perturbation coincides with an interval of possibly global climatic deterioration around 2700 years ago these results firmly establish deep water production in the nordic seas as a key component in the assortment of variables affecting climate during the holocene

a long term flood discharge record derived from slackwater flood deposits of the llobregat river ne spain abstract slackwater palaeoflood deposits were identified along two bedrock gorge study reaches of the llobregat river at pont de vilomara and monistrol de montserrat the compiled palaeoflood record consists of two principal flood series a a relatively complete record of low to high magnitude flood events from the last ca 100 years and b evidence of the largest palaeoflood events that have occurred over the last ca 2700 years the longer term extreme palaeoflood record indicates that the discharge of the 1971 flood the largest on record was exceeded on at least eight occasions with two periods of high magnitude flooding identified a the late bronze age 2500 2700 years ago and b the little ice age ad 1500 1700 at pont de vilomara palaeodischarge estimates of 3700 4300 m 3 s compare to a discharge of 2300 m 3 s for the 1971 event downstream at monistrol an estimate of 4680 m 3 s for flood deposits dated as ad 1516 1642 and believed to be those of the ad 1617 flood compared to 2500 m 3 s for the 1971 flood

past hydrological events reflected in the holocene fluvial record of europe abstract a comprehensive database of radiocarbon dated fluvial units in great britain poland and spain has been compiled to investigate the relationship between environmental change flooding and holocene river dynamics following the methodology recently developed by macklin and lewin macklin m g lewin j 2003 river sediments great floods and centennial scale holocene climate change journal of quaternary science 18 101 105 radiocarbon dates in fluvial sequences that coincide with a modification in sedimentation rate or style have been highlighted allowing geomorphologically significant changes in holocene river activity to be identified data analysis has been undertaken at both national and sub national scales and on catchments of different size type and land use history multiple phases of higher flood frequency characterized by accelerated erosion and sediment deposition on floodplains are recognized and compared with a range of climate proxies the relative and varying roles of climate and land use on river dynamics are considered and the value of the database for reconstructing past hydrological events as well as for predicting river response to future environmental change is assessed

fluvial geomorphology a perspective on current status and methods fluvial geomorphology seeks to study river landform history understand formative processes and predict changes using a combination of field observation experimental studies and numerical models a resurgence in fluvial geomorphology is taking place fostered for example by its interaction with river engineering and the availability of new analytical methods instrumentation and techniques these have enabled development of new applications in river management landscape restoration hazard studies river history and geoarchaeology this paper presents a perspective on recent advances in fluvial geomorphology and introduces a selection of papers presented during the fluvial geomorphology and palaeohydrology session within the sixth international conference on geomorphology held in zaragoza spain in september 2005

past hydrological events reflected in holocene history of polish rivers abstract a database of 335 radiocarbon dates from holocene fluvial sediments in poland has been compiled each sample is characterized by 25 parameters all samples were grouped into one of 7 regions characterized by hydrological regime and one of 8 depositional environments statistical analysis was used to enhance the palaeoenvironmental data and 17 phases may be distinguished 10 of which have a distinct sharp peak abandoned paleochannels 149 dates clearly reflect the major wetter phases of the holocene an opposite picture is presented by overbank aggradation 86 dates connected mainly with expansion of agriculture preliminary correlations are made on peat bog records changes in vegetation lake water level rates calcareous tufa and speleothems growth landslides phases and debris flow phases these show many convergences explained by climatic fluctuations during the holocene

reconstruction of a pleistocene meandering river in east hungary by vhr seismic images and its climatic implications abstract the upper 20 30 m of the pleistocene alluvial sequence on the tisza river hungary is investigated by 200 km of vhr single channel seismic sections frequent internal configurations such as 1 bundles of inclined reflections 2 trough shaped converging and 3 horizontal parallel reflections are interpreted respectively as lateral accretion of point bars abandoned channel fills and floodplain deposits the series of 5 8 m thick inclined strata sets occurring at the same depth throughout the area suggest the presence of a meandering river dated to about 43 47 ka in the late pleistocene according to osl data newly recorded quasi 3d seismic profiles reveal that each 1 3 km long inclined series correlates with an individual point bar continuously migrating in the same direction small deviations in the direction of migration are caused by natural wandering of the meander bend morphometric parameters of point bars are used to calculate ancient channel parameters width and depth of 200 500 m and 5 8 m respectively values imply a channel forming discharge of q 400 900 m 3 s these results imply a greater amount of runoff and supply in the basin during mis3 compared to the present day long lasting meandering indicates the role of local factors and a different fluvial environment compared to the commonly anastomosing systems in nw europe our data support the thesis of the three axis drainage system for the basin new evidence is provided for the antecedent existence of a temporally active third trunk river in addition to the ancestors of danube and tisza rivers contrary to the present day two axis drainage pattern