holocene alluvial sediment storage in a small river catchment in the loess area of central belgium abstract soil erosion and sediment deposition widely affect landscape development particularly in erosion prone areas with loess derived soils nevertheless until now few attempts were made to quantify soil losses and sediment storage over long centennial or millennial timescales in this study the holocene alluvial sediment storage in a small river catchment 52 km2 of the belgian loess belt is estimated and a preliminary sediment budget for the catchment is presented in the valley of the nethen river c 13 km long a detailed survey of the alluvial sediment archive was conducted hand augerings and percussion drillings were made along cross valley transects at 12 locations in the catchment ams 14c dating of peat samples provided a temporal framework for the interpretation of the cores results show that the thickness of holocene sediment deposits in the nethen valley is 4 to 6 m which corresponds to a total clastic sediment mass of 14 106 t stored in the valley bottom three alluvial units could be distinguished and associated with deposition phases from 9600 to 2900 b c 2900 b c to a d 1000 and a d 1000 to present in contrast to the older sediments units 1 and 2 deposits from the last 1000 year unit 3 contain little organic matter they are seldom intercalated with peat layers and devoid of tufa unit 3 reaches a thickness of c 2 m thereby representing 50 of the holocene sediment mass stored in the alluvial plain the mean sedimentation rate in the alluvial plain for this last phase is 26 t ha 1 a 1 which is about tenfold larger than the sedimentation rates calculated for the older holocene sediment units sediment supply towards the alluvial plain has therefore increased tremendously since medieval times these results are in contrast to dating results obtained for colluvial sediments in a nearby dry valley within the catchment of the nethen where soil erosion and sediment deposition started in the early iron age and was already substantial during the roman age this means that there is a time lag of about one millennium between the onset of high sedimentation rates in the upstream area and high deposition rates in the alluvial plain this is probably caused by a change in coupling sediment connectivity between the plateau slopes and rivers as soil erosion proceeds first the dry zero order valleys in the catchment act as sediment traps and only after these are filled sediment reaches the floodplains the preliminary sediment budget for the nethen catchment illustrates that 50 of the sediment that was eroded during the holocene was stored in colluvial deposits which are mainly located on footslopes and in dry valley bottoms another 29 of the sediment mass is stored in the alluvial plain

fluvial development and the sediment regime of the lower calder ribble catchment northwest england in the lower reaches of the calder lancashire tributary of the ribble catchment northwest england five river terraces set into the surrounding glacial terrain have been mapped and their underlying sediments radiocarbon dated the earliest terrace t1 reflects sandur style deposition during deglaciation and it aggraded in a reach cut into glacial diamict and glaciolacustrine muds incision below t1 spanned the start of the holocene driven by a combination of reduced sediment supply under a stabilising landscape and lower base levels t2 had aggraded and was being abandoned by 4000 bc its formation latterly involving a period of comparative stability in terms of channel migration perhaps a function of extensive forest cover and sea levels reaching above present day levels the last 3000 years were marked by substantial changes in the sedimentary regime with increased and varying sediment supply driving cycles of cut and fill and greater lateral channel migration these changes coincided with the first widespread and substantial reductions in forest cover and a progression towards an agricultural landscape between the aggradation of terraces t3 and t4 there was a substantial increase in sediment supply which is broadly in keeping with the erosion history in the surrounding uplands this sediment slug appears to have induced a switch from highly sinuous meandering to lower sinuosity channels characterised by lateral scroll style migration late holocene vegetation changes particularly woodland removal driven by anthropogenic land pressure appear to have rendered the floodplain prone to channel migration and the landscape more susceptible to erosion

nonuniform response of the major surface currents in the nordic seas to insolation forcing implications for the holocene climate variability 1 high resolution sediment cores from the voring plateau the north iceland shelf and the east greenland shelf have been studied to investigate the stability of major surface currents in the nordic seas during the holocene results from diatom assemblages and reconstructed sea surface temperatures ssts indicate a division of the holocene into three periods the holocene climate optimum 9500 6500 calendar cal years bp the holocene transition period 6500 3000 cal years bp and the cool late holocene period 3000 0 cal years bp the overall climate development is in step with the decreasing insolation on the northern hemisphere but regional differences occur regarding both timing and magnitude of sst changes sites under the direct influence of the norwegian atlantic current and the irminger current indicate sst cooling of 4 5 c from early holocene to present compared to 2 c recorded under the east greenland current superimposed on the general holocene cooling trend there is a high frequency sst variability which is in the order of 1 1 5 c for the voring plateau and the east greenland shelf and 2 5 3 c on the north iceland shelf

trends and controls of holocene floodplain sedimentation in the rhine catchment article i nfo holocene floodplain sedimentation in the rhine catchment is controlled by human and climate impacts intricate river behaviour modifies the fluvial response to the external impacts making cause effect analysis difficult especially on large spatial scales to better understand the relative importance and interdependencies of external and internal controls temporally resolved floodplain sedimentation rates are established using three different methods i floodplain storage studies on the trunk stream ii depth age analysis of overbank deposits from different parts of the catchment and iii cumulative frequency distributions of 14 c ages from floodplain deposits from various parts of the catchment the applied methodology strongly differs with the available temporal resolution and the size of the corresponding catchment all three methods show a strong increase in sedimentation rate for more recent periods that can be linked to increasing human impact evidences for climate impacts and intricate river behaviour are less clear and hindered by insufficient temporal resolution of the currently available data

spatio temporally variable response of fluvial systems to late pleistocene climate change a case study from central germany abstract the change of the earth s climate and anthropogenic forcing challenge catchment management as the deliberate use of the fluvial system s natural resources depends to some extent on the predictability of the system s variable sensitivity to external impacts the alluvial history of the wetter valley in central germany provides an example of the occurrence of a spatio temporally variable catchment sensitivity to the late pleistocene climate change empirical models that are based on sediment flux controls such as sediment supply transport capacity and gradient serve to explain differential floodplain construction during the early younger dryas the large scale basin upland morphology caused localised divergent cooling impacts and vegetation changes which generated reach scale variable sediment transport system states in the wetter valley the spatial arrangement of reach scale variable response is ascribed to the tectonically driven morphological configuration of the wetter catchment the crucial amplification of differential floodplain construction can be assigned to the spatially variable availability of a surplus of laacher see tephra particles in manner of a pulsed sediment input the ubiquitous tephra cover was previously deposited by the laacher see volcano event in the upper allerod thus the reach scale variable response during the early younger dryas can be deemed to have been climatically triggered but superimposed by an internally driven specific upstream catchment response the documented processes of late quaternary alluviation in the wetter valley imply the need for whole catchment approaches the latter are a prerequisite to reveal the occurrence and causalities of variable fluvial response in relation to external impacts that interact with internal morphological controls this is seen to be crucial to achieve an improved predictability of future environmental change in fluvial landscapes

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

human impact on land ocean sediment transfer by the world s rivers abstract land ocean transfer of sediment by rivers is a key pathway for material transfer on earth contemporary data on the sediment loads of rivers provide clear evidence of significant recent changes in the sediment fluxes of several rivers in response to human impact the key drivers of increased sediment loads include land clearance for agriculture and other facets of land surface disturbance including logging activity and mining although programmes for soil conservation and sediment control can result in reduced sediment loads the trapping of sediment by dams represents the dominant cause of reduced loads this influence is currently assuming increasing importance at the global scale any attempt to link these drivers to changes in the global land ocean sediment flux must take account of the aggregation and buffering effects that operate in larger basins which can cause damping and even removal of signals of increasing flux within the upstream basin and complicate the link between upstream and downstream response to human impact further work is required to provide a precise quantitative assessment of the human impact on global land ocean sediment fluxes and the net effect of increasing and decreasing fluxes particular attention must be paid to the temporal perspective and the variation of impact trajectories in different areas of the globe and for river basins of different sizes

long term and millennial scale climate variability in northwestern france during the last 8850 years vegetation and quantitative climate reconstructions from a northwestern france shelf core vk0358bis show orbital and suborbital climate variability for the last 8850 years in this region a long term cooling trend in summer temperatures marked by gradual temperate and humid forest decline parallels cooling in greenland and the decrease of mid latitude summer insolation reduction until at least 2000 cal yr bp at the long term scale the lowering in seasonal contrast revealed by vegetation changes follows the increase of precession corylus woodlands spread at the expense of deciduous quercus forest between 8740 and 8390 cal yr bp linked with the high seasonality conditions that counterbalancing the long term astronomical forcing trend were amplified by the north atlantic high latitudes winter sea ice expansion high seasonality conditions resulted from the agassiz and ojibway final outburst episodes and consequent gradual reduction of the meridional overturning circulation moc between 8390 8060 cal yr bp a sudden corylus woodland decline marks the 8 2 kyr cold event in northwestern france probably triggered by the severe moc reduction leading to the additional drop in winter temperature over europe and greenland nonetheless seasonality remains high during this interval the high seasonality conditions detected in vk03 58bis between 8740 and 8060 cal yr bp reflects the multicentennial scale climate cooling 8 6 8 0 kyr episode of the north atlantic following the agassiz and ojibway final outburst episodes climate became more stable however millennial scale climate cooling episodes are recorded in vk03 bis and are characterized by weak winter cooling and increases in precipitation furthermore dinocyst analysis and benthic gastropod turritella communis occurrences indicate regional changes such as the southward migration of the boreal biogeographical zone between 8740 and 8480 cal

a temporarily changing holocene sediment budget for a loess covered catchment central belgium abstract this study presents a holocene sediment budget for the nethen catchment a typical river catchment 55 km 2 in the belgian loess belt soil erosion and hillslope sediment storage are quantified by extrapolating detailed data obtained from soil profile truncation studies in three representative zero order sub catchments floodplain sediment storage is estimated by augerings along several transects across the main river and some of its tributaries the sediment budget shows that ca 38 of the soil eroded during the holocene is redeposited as colluvium on hillslopes and in dry valley bottoms another 23 of the eroded sediment is now stored as alluvium in the floodplain the remaining 39 or 21 10 6 mg is exported from the catchment dating of both colluvial and alluvial sediment deposits reveals that sediment dynamics between the hillslopes the dry valley bottoms and the floodplain behave highly non linearly before 500 bc sediment delivery from the hillslopes to the river channels was near maximum however since the onset of significant agriculture in the late bronze age early iron age increased rates of soil erosion are only reflected in the colluvium but not in the floodplain resulting in very low hillslope sediment delivery ratios from the medieval period onwards soil erosion increased even further mainly as a result of a further increase in agricultural land use but now also accelerated floodplain sedimentation took place due to an improved slope channel coupling and the management of floodplains

changes in sediment flux and storage within a fluvial system some examples from the rhine catchment the rhine river system can look back on a long history of human impact whereas significant anthropogenic changes to the river channel started only 200 years ago the impacts of land use have been felt for more than 7500 years here we review results from several case studies and show how land use change and climate impacts have transformed the fluvial system we focus on changes in sediment delivery pathways and slope channel coupling and show that these vary in time and depend on the magnitude of a rainfall event these changes must be accounted for when trying to use sediments as archives of land use change and climatic impacts on fluvial systems for example human impact is recorded in slope deposits only as long as rainfall intensity and runoff generation do not exceed the threshold for gullying similarly climatic impacts are only recorded in alluvium when both the landscape is rendered sensitive by human activities e g deforestation and rainfall thresholds for gullying are exceeded copyright 2003 john wiley sons ltd

oscillations of the water balance during the holocene in interior central europe features dating and consequences abstract the continental water balance depends on precipitation and evaporation with the latter due to temperature moreover both the components of weather and climate are influenced by the annual seasonality all these factors have changed during the last millennia and periods of significant moisture have alternated with ones of low moisture evidence of these oscillations results from geostratigraphical subdivision of sequences of freshwater lime deposits and from lake level changes of inland lakes but also from many archaeological observations concerning settlement distribution all these observations reflect oscillations that can be correlated through archaeological and other dating alternation of drier and moister periods in the course of the central european holocene can be recognized

reflection of the glacial interglacial cycle in the evolution of the vistula river basin poland a variety of factors has controlled the evolution of the vistula river valley they include climatically induced changes of the river runoff and sediment load glacial advances and rapid variations of the base level as well as the influence of the tectonic factor the first order climatic cycles are reflected in separate terrace fills the second order fluctuations may be represented by separate cuts and fills by the change of the facies or by the change in the granulometric composition the analysis of the changes in the longitudinal profile helped to discover a great variety of different valley reaches and a general tendency to smooth the long profile during the quaternary

greenland gisp2 ice core and historical indicators of complex north atlantic climate changes during the fourteenth century the paper uses greenland gisp2 ice core data together with historical documentary information to investigate the nature of climate changes that took place between ad 1270 and 1450 across the north atlantic region detailed deuterium and deuterium excess time series resolved to c 8 10 samples per year are used to reconstruct relative changes in greenland air temperature and past changes in sea surface tem perature across the western north atlantic the data show that sea surface temperatures during the late thirteenth century and the majority of the fourteenth century were characterized by relatively high amplitude warming and cooling events these changes preceded a marked reduction in the amplitude of the sea surface temperature changes c 30 40 years before the well known change in northern hemisphere tropospheric circulation characterized by a marked increase in regional storminess that started between c ad 1400 and 1420 the time interval between ad 1270 and 1450 also appears over greenland to have fea tured several short lived phases of marked air temperature lowering that were rarely ever equalled during succeeding centuries we believe that the climate changes described here are of considerable importance in understanding climate dynamics of the north atlantic region since they took place at a time when the north atlantic oscillation nao may have been weak the results also show that the marked change in atmospheric circulation coincident with a significant increase in north atlantic storminess at c ad 1400 1420 possibly the biggest such change in the holocene took place after the strong perturbations in north atlantic sea surface temperature both warming and cooling described here as well as after several episodes of air temperature lowering over greenland

mechanical behavior of high strength granite for new prestressed stone structures abstract the present paper analyzes the internal destruction process of high strength granite under compression focusing inconsistencies between some conventional theories and the observed reality it is proposed that the crack progression is a result of the relative displacement of two fitted irregular faces which implies an increase of the gap between them and tensile forces at the tips this model explains some aspects of the mechanical behavior of granite a spalling of granite laminae without buckling processes b consequences of the destruction of crack face irregularities c effect of the grain size in the compressive strength the paper also discusses some loading conditions effects in the compressive strength of granite load distribution constraints of transversal deformation on the loaded ends of specimens long term loads cyclic loads

the recent history of erosion and sedimentation on the southern tablelands of southeastern australia sediment flux dominated by channel incision abstract as in other regions colonised from europe within the last few centuries australia s vegetation and soils have been dramatically changed by clearing cropping and grazing in southeastern australia particularly on the southern tablelands the impacts of european settlement are clearly manifested by channel incision by using stratigraphic and documentary evidence in conjunction with aerial photographs sediment budgets for the post settlement period have been constructed to define the fluxes and stores of sediment for each of the major geomorphic components of the 136 km2 catchment of jerrabomberra creek near canberra using these budgets and some plausible assumptions it has been possible to approximate the history of both the sediment delivery ratio and sediment yield for this catchment while the quantities estimated in this analysis are approximations the trends through time are credible sediment yield increased rapidly to a peak after european settlement and has returned to a level between the peak and the pre european value the delivery ratio has followed a similar trend the most general conclusion to emerge is that in this landscape both the total sediment flux and the sediment yield of the catchment have been dominated by channel erosion this result is contrary to the findings in many parts of the world where sheet and rill erosion dominates the fluxes the soil conservation implication of these results is clear to control off site effects of erosion the focus must be on the channels

establishing a holocene sediment budget for the river dijle abstract a holocene sediment budget was constructed for the 758 km 2 dijle catchment in the belgian loess belt in order to understand long term sediment dynamics hillslope sediment redistribution was calculated using soil profile information from 809 soil augerings which was extrapolated to the entire catchment using morphometric classes as large parts of the forests within the catchment prove to have undergone little or no erosion since medieval times a correction was applied for the presence of forests total holocene erosion amounts 817 66 mt for the catchment of which 327 34 mt was deposited as colluvium this corresponds with a net holocene soil erosion rate of 10 8 0 8 10 3 mg ha 1 for the entire dijle catchment alluvial deposits were studied through 187 augerings spread over 17 cross valley transects the total alluvial sediment deposition equals 352 11 mt or 42 of total eroded sediment mass results indicate that at the scale of a medium sized catchment the colluvial sediment sink is as important as the alluvial sediment sink and should not be neglected as a result the estimation of erosion through alluvial storage and sediment export would yield large errors dating of sediment units show an important increase in alluvial deposition from medieval times onwards indicating the important influence of agricultural activities that developed from that period mean sediment export rates from the catchment for the last 1000 1200 years range between 0 8 and 1 3 mg ha 1 a 1 and are consistent with present suspended sediment measurements in the dijle erosion for agricultural land for this period is 9 2 2 2 mg ha 1 a 1 sediment budgets for the various tributary catchments provide an insight in the sources and sinks of sediment at different scales within the catchment

morava river floodplain development during the last millennium stražnicke pomoravi czech republic floodplain sediments deposited along the lower course of the morava river eastern czech 206 pb 207 pb and pop ddt pcb analysis and 137 cs activity data thecu trienmethodwasusedforstratigraphicallycorrelatingthesedepositsbasedonthevariationofexpand able clay minerals in the sediments the resulting stratigraphic pattern reveals the alluvial history of the cur rently active river channel system since the end of the first millennium ad fine overbank clayey sediments deposited during the mediaeval warm period were eroded from cultivated fields newly formed during mediaeval colonization between 1250 and 1450 these fine deposits are overlain by coarser floodplain sedi mentsofthe littleiceage indicatingachangeinthesedimentsourcesincethesixteenthcentury ad anda substantial increase in the sediment load in the second half of twentieth century the straunicke pomoravi floodplaindepositsrepresentavaluablepalaeoenvironmentalarchiveofthelastmillennium containingrecords offluvialprocessesconsiderablyalteredbyhumanactivities

sensitivity of west and central european river systems to environmental changes during the holocene a review abstract sediment deposition in floodplains is an essential part of the sediment dynamics of a catchment these sediment dynamics can vary largely on a holocene time scale under the influence of driving forces such as land use and climatic variations in this paper we review the holocene floodplain sediment deposition history of rivers in west and central europe with special attention to the influence of climate and land use variability during the early holocene preboreal to atlantic period most floodplains were rather stable with limited floodplain aggradation after this initial phase of relative stability sedimentation rates increase during the middle and late holocene with often the most important deposition phase during the last 1000 to 2000 a the start of the increase in sedimentation varies spatially with an earlier start in the west france germany then in the east poland belarus ukraine while there are also local differences between regions which are settled early e g loess regions compared to later settled regions the sedimentation history of most floodplains can be linked to the local land use history while influence of climatic variations on floodplain aggradation is often reported to be of minor importance processes related to bedload are often reported to be more influenced by climatic events relationships between the driving forces and the sediment history are mainly based on synchronicity and there is seldom proof for a direct causal relationship future research should focus on a system based approach integrating the floodplain deposition in the entire sediment dynamics which includes also erosion colluvial deposition and export main research questions that need further attention include integration of system based concepts like landscape connectivity and buffering effects and also the assessment of the individual contribution of land use changes and climatologic variations on the sediment dynamics detailed sediment budget studies combined with modeling studies can make an important contribution to the understanding of floodplain sediment dynamics

geomorphological facies reconstruction of late quaternary alluvia by the application of fluvial architecture concepts abstract this paper investigates the methodical implications the benefits and the constraints of applying the fluvial architecture concept to late quaternary shallow subsurface alluvial deposits the focus is upon a typical small to mesoscale valley floor of the temperate zone the studied reach is part of the river wetter catchment 517 km 2 in central germany a large number of studies on late quaternary terrestrial paleoenvironmental change of the temperate zone refer to such small to mesoscale catchments which are mostly occupied by mixed to suspended load rivers as in many cases mostly coring based evidence is available the observation and measurement is limited to lithology and lithofacies boundaries facies geometry must be inferred moreover in those environments differences in lithofacies are obscured by a significantly reduced range of grain size distributions an example of an ancient channel belt of late glacial to holocene age serves to delineate the methodical practice and utility of the fluvial architecture approach field evidence is obtained from detailed cross sectional surveys and comprises descriptions of lithofacies structural pedogenetical biotic features munsell color and total organic carbon magnetic volume susceptibility cross sectional lithofacies information is represented by spatially attributed scaled borehole logs the example also accentuates the need for applying additional stratigraphical methods such as physical age determination macrofossil analysis and tephrological stratigraphy these methods form the basis to discern stacked channel facies and derive a diachrony of channel forms thus the adapted architecture approach provides a significant surplus of information on channel dimensions ages and channel floodplain interconnectedness distinct fluvial landforms such as channels levees abandoned channels swamps and floodplain flats can be highlighted a number of methodical constraints are discussed in detail e g the sharpness of channel element geometry and the underlying ordering of bounding surfaces moreover it is shown that the analytical process resembles an iterative looping process that is led by deduction many geomorphologists and multi disciplinary floodplain researchers collect sedimentary data but still neglect utilizing the potential of architectural analysis the study makes clear that sedimentological approaches used in big river floodplains also apply to small valleys in fact the procedures for facies reconstruction need to be adjusted to each individual case study alluvial architecture analysis provides the tools to reveal interconnectedness or disconnectedness of channel near channel and overbank fluvial landforms which is essential for a geomorphological understanding of floodplain evolution

quantification and regulation of organic and mineral sedimentation in a late holocene floodplain as a result of climatic and human impacts taligny marsh parisian basin france quantification in grams per metres squared per year of the sediment accumulation in a flood plain marsh located in the southwestern parisian basin showed that there is no close relationship between the accumulation of organic matter om and mineral matter mm during the late holocene and provided an accurate view of the distinct yield and storage conditions of both sediment components endogenic om accumulation in peaty sediments is not related to the climate but to felling of the alder forest and its substitution by cyperaceae and paludal taxa in the marsh iron age and middle ages mm accumulation expresses mainly the sediment yield on the slopes determined by landuse during an initial phase from the late neolithic to the early middle ages land use change from crop cultivation to pastureland possibly related to climate deterioration led to a decrease in the sediment yield during a second phase since the early middle ages the considerable development of crop cultivation over pasturing even during periods of climate deterioration such as the little ice age led to a sharp increase in sediment yield however although sediment yield was high the hydrodynamics in the fen did not favour particle retention thus since the neolithic yield and storage of om and mm sediment have been marked by human activities initially with high climatic stress but since the middle ages without significant climatic stress

fluvial system evolution and environmental changes during the holocene in the mue valley western france geomorphological and palaeoenvironmental research on holocene sedimentation in the mue valley provides evidence for fluvial system changes related to climate and human activities in normandy a poorly studied area of the paris basin the 24 km long valley bottom has been investigated through a systematic survey it shows an original longitudinal sedimentary pattern in relation with valley morphology and local geological controls minerogenic tufaceous and peaty deposits provide opportunities for multi proxy analyses and radiocarbon dating control sedimentation began around 9500 14c bp with silt deposition in a meandering system the boreal and the lower atlantic periods 8500 6000 14c bp were mainly characterized by unlithified calcareous tufa locally these deposits are very thick 7 to 13 m the tufa formed barrages across the valley bottom providing an autogenic control on upstream sedimentation during the upper atlantic period 6000 4700 14c bp the valley experienced a decrease in calcareous sedimentation and the development of organic deposits at the beginning of the subboreal 4700 3500 14c bp peat deposits expanded especially behind the tufa barrages the valley bottom was characterized by large marshy areas whereas the regional vegetation was progressively modified by human activities at the end of the subboreal 3300 3000 14c bp the infilling of the valley by calcareous silt was caused by an increase of river activity related to climatic and land use changes from the iron age and gallo roman periods 2800 1700 14c bp the valley bottom was filled by silty overbank deposits related to an increase of soil erosion the slopes and river system were once again coupled and the fluvial system functioned as a continuum from upstream to downstream the alluvial record of the mue valley reflects a broad regional pattern of environmental changes but presents particular features which highlight the need of longitudinal studies to take into account spatial and temporal discontinuities of holocene hydro sedimentary systems even in small order valleys

soil erosion and sediment deposition in the belgian oess belt during the holocene establishing a sediment budget for a small agricultural catchment a method to establish a holocene sediment budget for a 103 ha agricultural catchment representative for the belgian loess belt is presented soil erosion and sediment deposition were determined based on 185 coring locations and a large excavation in the valley bottom results were integrated in a gis and interpolation techniques applied to derive spatial patterns of erosion and sedimentation total soil erosion sediment deposition and sediment export were calculated and the results show that volumes are highly dependent on the interpolation technique used sediment delivery ratios between 20 and 42 are derived and are consistent with data reported in previous studies this clearly shows that the majority of the sediments produced during the holocene have been stored near their source area and have not been delivered to the downstream rivers the spatial distribution of soil erosion and sediment deposition within the catchment is strongly dependent on slope gradient and position within the catchment which suggests that since human impact began topography has been the main factor determining long term soil erosion and sedimentation

fennoscandian summers from ad 500 temperature changes on short and long timescales quantitative estimates of 1480 years of summer temperatures in northern fennoscandia have previously been derived from continuous treering records from northern sweden here we show the results of spectral analyses of these data only a few peaks in the spectra are consistently significant when the data are analyzed over a number of sub periods relatively timestable peaks are apparent at periods of 2 1 2 5 3 1 3 6 4 8 32 33 and for a range between 55 100 years these results offer no strong evidence for solar related forcing of summer temperatures in these regions our previously published reconstruction was limited in its ability to represent long timescale temperature change because of the method used to standardize the original tree ring data here we employ an alternative standardization technique which enables us to capture temperature change on longer timescales considerable variance is now reconstructed on timescales of several centuries in comparison with modern normals 1951 70 generally extended periods when cool conditions prevailed prior to the start of the instrumental record include 500 700 790 870 1110 1150 1190 1360 1570 1750 a d with the most significant cold troughs centred on about 660 800 1140 1580 1620 and 1640 predominantly warm conditions occurred in 720 790 870 1110 and 1360 1570 with peaks of warmth around 750 930 990 1060 1090 1160 1410 1430 1760 and 1820

holocene sediment budgets in two river catchments in the southern upper rhine valley germany abstract the holocene sediments of two catchments in the southern upper rhine valley have been quantified as part of the german lucifs programme rheinlucifs which aims to quantify sediment fluxes in the rhine catchment since the onset of agriculture in the neolithic about 7500 years ago the spatial distribution of the alluvial and colluvial sediments was derived using geological maps with information on the thickness of these sediments from various sources including auger profiles and data from excavations the sediments were subdivided into characteristic sedimentary storage types according to the different types of landscapes for each of the sedimentary storage types an average thickness was assessed so that an integral sediment balance for the holocene could be derived for the different types of landscapes in the study area 32 holocene sedimentary storage types were determined 21 in the elz catchment 1500 km 2 and 11 in the mohlin catchment 230 km 2 by adding up the sediment volumes of all single sedimentary storage types the total holocene sediment volumes for the two catchments were calculated erosion depths were determined by dividing the sediment volumes through the potential erosion areas slope 2 and by assuming a sediment delivery ratio sdr between 0 and 0 4 the total erosion for the potential erosion areas during the holocene was calculated as 31 61 cm in the elz catchment and 44 79 cm in the mohlin catchment

age and source of colluvial sediments at vaihingen enz germany abstract colluvial sediments accumulated on the lower slopes of a ridge as a result of past and present soil erosion were dated by optical 14 c and archaeological methods this allowed us to reconstruct the depositional history of the colluvium and also to identify temporary sedimentary sinks in its transportational pathway a cascade model of colluvium formation is developed colluvial sediments resulting from early soil erosion in the neolithic to iron age periods were mainly deposited on the upper slopes significant deposition on the lower slope occurred for the first time during the iron age and roman period since then deposition rates have increased because of more intensive land use

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

last glacial interglacial cycle in the evolution of river valleys in southern and central poland abstract the last glacial interglacial cycle is represented usually by several cuts and fills which have formed 2 3 terrace steps from the last cold stage and by two or more fills of lateglacial holocene age their number depends on the size of the river valley and the position in the longitudinal profile the sequence of changes reflects shorter stadial interstadial climatic fluctuations generally aggradation dominates during the cooler phases of the vistulian and during the interpleniglacial the most distinct erosional phases occurred during the change from a more oceanic to a more continental climate before the maximum extension of the ice sheet 25 20 ka bp and during the upper pleniglacial lateglacial transition 15 13 ka bp the second phase coincides with the rapid downcutting in the lower course of the main vistula valley which had been blocked earlier by the scandinavian ice sheet in the holocene aggradation prevailed accelerated by anthropogenic soil erosion it was only in the mountain foreland that shorter lived hydrological changes resulted in well expressed several cuts and fills

fluvial history of the northern upper rhine river southwestern germany during the lateglacial and holocene times abstract three time slices were focused on reconstruction of the lateglacial and holocene landscape evolution in the northern upper rhine rift valley the fluvial history of the northern upper rhine river during the last 15 000 years is characterised by repeated rapid changes of fluvial morphodynamics and sedimentation conditions in consequence the floodplain of the rhine river may be subdivided into three different meander generations which differ mainly on morphological lithological and pedogenetical criteria using complementary dating techniques pollen irsl ams 14c a detailed chronology was obtained for the floodplain sediments e g overbank deposits peat bogs aeolian dune sands of the rhine river and its tributary the neckar river bergstrasen necker while the latter became completely abandoned during the younger dryas period the rhine river probably started meandering at the onset of the allerod period and most likely continued its meandering pattern since the lateglacial the change from the oldest meander generation to the older meander generation occurred during the late phase of the atlantic period however the timing of the onset of the younger meander generation is not known in detail at present probably it started to develop in the late subboreal period or at the transition from the subboreal to the subatlantic period

record of volcanism since 7000 b c from the gisp2 greenland ice core and implications for the volcano climate system sulfate concentrations from continuous biyearly sampling of the gisp2 greenland ice core provide a record of potential climate forcing volcanism since 7000 b c although 85 percent of the events recorded over the last 2000 years were matched to documented volcanic eruptions only about 30 percent of the events from 1 to 7000 b c were matched to such events several historic eruptions may have been greater sulfur producers than previously thought there are three times as many events from 5000 to 7000 b c as over the last two millennia with sulfate deposition equal to or up to five times that of the largest known historical eruptions this increased volcanism in the early holocene may have contributed to climatic cooling

a sensitive high resolution record of late holocene climatic change from a raised bog in northern england proxy climatic data in the form of plant macrofossils have been analysed from a 5 m core from bolton fell moss cumbria uk detailed analysis of peat from the upper 50 cm of this core is used to demonstrate a strong correlation between changes in the relative proportion of taxa and known climatic changes over the last 1000 years the record of changes in bog vegetation contained within the peat profile is used to reconstruct changes in bog surface wetness for the latter half of the holocene as bog surface wetness is directly controlled by the prevailing climatic conditions this reconstruction can be viewed as a proxy climate record twelve radiocarbon age estimates on the 5m core suggest that between 50 and 500 cm peat accumulated at a relatively constant rate of 12 4 yr cm 1 the regular sampling intervals thus provide a time series of past bog surface wetness spectral analyses of this series indicates that wetness changes are cyclic with a ca 800 year periodicity

july mean temperature and annual precipitation trends during the holocene in the fennoscandian tree line area pollen based climate reconstructions july mean temperature and annual precipipation during the last 9900 cal yr bp were recon structed from pollen assemblages preserved in a sediment core from northern finland quantitative recon structions were performed using a modern pollen climate calibration model based on weighted averaging partial least squares regression the predictive ability of the model was evaluated against modern meteoro logical data using leave one out cross validation the prediction error for july mean temperature is c 1 0 c and for annual precipitation 340 mm the july mean temperatures during the earliest holocene were low c 1 1 0 c and annual precipitation was high c 600 800 mm between 8200 and 6700 cal yr bp july mean temperatures reached their maxima 12 5 13 0 c which are c 1 4 1 7 c higher than at present at the same time precipitation decreased during the late holocene july mean temperatures declined and the last 2000 years have been the coolest since the early holocene precipitation has slightly increased the spatial coherence between our results and of several other climate reconstructions from northern europe indicates that the holocene climate was strongly influenced by north atlantic oceanic and atmospheric circulation patterns we propose that the distinctly oceanic climate of the early holocene was due to enhanced westerly latitudinal airflow which was replaced at c 8200 cal yr bp by a more meridional flow pattern and by the development of predominantly anticyclonic summer conditions

the fluvial cycle at cold warm cold transitions in lowland regions a refinement of theory abstract a previously established non linear theory of river cyclicity as a response to climate change states that short phases of fluvial instability occur both at the transition from relatively warm temperate to cold periglacial and from relatively cold to warm periods such instability typically starts with vertical erosion successively followed by sedimentary fill of the erosive scar in spite of frequent confirmation of this theory by geomorphological reconstructions a few problems arise first there are fewer incision phases than climatic transitions secondly remnants of erosion at cold warm transitions are scarce in contrast to obvious erosion relics at warm cold transitions furthermore it appears that the incision style is strikingly different at both kinds of climatic transitions similarly the long stable phases are also expressed in terms of different floodplain development in cold and warm periods these arguments require a modification of the general non linear theory at the transition from relatively temperate to colder conditions rivers transformed gradually from a regular low energy single channel course to a periodically high energy multi channel type the latter braided type is characterized by intense lateral movement rather than by deep vertical erosion this results in a well expressed morphology of wide extensive floodplains and terraces in contrast the linear and constrained meandering channels incise with small width depth ratio and build floodplains of limited lateral extent consequences are twofold 1 the spatial limitation of the deeply incised meandering valleys at the beginning of warm periods counts against their recognition 2 relatively strong lateral migration of the braided rivers removes most traces of previous meandering systems which contrasts with the limited lateral activity of confined meandering channels it means that in a warm cold warm alternation generally only one phase of vertical erosion is preserved the one that is caused by the high energy braided river at the start of the cold period

alluvial and colluvial sediment storage in the geul river catchment the netherlands combining field and modelling data to construct a late holocene sediment budget abstract we used a combined approach of a two dimensional erosion and hillslope sediment delivery model watem sedem and detailed geomorphological reconstructions to quantify the different components in a sediment budget for the geul river catchment southern netherlands since the high middle ages hillslope erosion and colluvium deposition were calculated using the model while floodplain storage was estimated using field data our results show that more than 80 of the total sediment production in the catchment has been stored as colluvium mostly generated by hillslope erosion while almost 13 is stored in the floodplain since the high middle ages this situation resembles a capacity limited system model results for the period prior to the high middle ages with a nearly completely forested catchment show that far less sediment was generated and that most of the sediments were directly transported to the main river valleys or out of the catchment a supply limited system geomorphological analysis of a large alluvial fan shows the sensitivity of the study area to changes in the percentage of arable land our combined field data modeling study presents an elegant method to calculate a catchment sediment budget for a longer period and is able to identify and quantify the most important sediment storage elements furthermore it provides a valuable tool to calculate a sediment budget while only limited dated fluvial sediment sequences are available

climatic versus human impact on the holocene sedimentation in river valleys of different order examples from the upper dnieper basin belarus records from floodplain deposits in selected river valleys of the dnieper river basin belarus were studied to reconstruct the phases of natural and anthropogenic environmental changes in the holocene sediment archives in the main valley and its four tributaries of different orders were studied by means of lithological and geochemical methods including grain size analysis x ray fluorescence analysis spectral analysis spore and pollen analyses and radiocarbon dating some differences in the response of different order fluvial systems to climate changes and human impact have been revealed fluvial deposits in the dnieper valley and in first order valleys contain records on the regional scale natural environmental changes while human impact is clearly pronounced only in deposits of the last millenium fluvial deposits in the valleys of second order record river evolution only since the neoholocene at the same time the lacustrine or carbonate freshwater deposits in these valleys contain the records of environmental changes in the entire holocene changes in the sequence and composition of fluvial deposits due to human impact occurred in high order valleys almost 2000 years later since 500 years bp as compared with pollen data

floodplain sedimentation in the upper mississippi valley natural versus human accelerated abstract understanding the time scales and pathways for response and recovery of rivers and floodplains to episodic changes in erosion and sedimentation has been a long standing issue in fluvial geomorphology floodplains are an important component of watershed systems because they affect downstream storage and delivery of overbank flood waters and they also serve as sources and temporary sinks for sediments and toxic substances delivered by river systems here 14c and 137cs isotopic dating methods are used along with ages of culturally related phenomena associated with mining and agriculture to determine rates of sedimentation and morphologic change for a reach of the upper mississippi river and adjacent tributaries in southwestern wisconsin and northwestern illinois the most important environmental change that influenced fluvial activity in this region during last 10 000 years involved the conversion of a late holocene mosaic of prairie and forest to a landscape dominated by cropland and pastureland associated with euro american settlement results presented herein for the upper mississippi valley umv show that the shift from pre agriculture natural land cover to landscape dominance by agricultural land use of the last 175 200 years typically increased rates and magnitudes of floodplain sedimentation by at least an order of magnitude accelerated overbank flooding led to increased bank heights on tributary streams and in turn contributed to more frequent deep flows of high energy these high energy flows subsequently promoted bank erosion and lateral channel migration and the formation of a historical meander belt whose alluvial surface constitutes a new historical floodplain inset against the earlier historical floodplain the new historical floodplain serves as a flume like channel that provides efficient downstream transport of water and sediment associated with moderate and large magnitude floods floodplains on lower tributaries however continue to experience rates of overbank sedimentation that are of anomalously high magnitude given improved land cover and land conservation since about 1950 this lower valley anomaly is explained by minimal development of historical agriculture period meander belts because of relatively low stream power in these channel and floodplain reaches of relatively low gradient in general long term pre agriculture rates of vertical accretion between about 10 000 and 200 years ago averaged about 0 2 mm yr 1 in tributary watersheds smaller than about 700 km2 and about 0 9 mm yr 1 on the floodplain of the upper mississippi river where the contributing watershed area increases to about 170 000 km2 on the other hand rates of historical vertical accretion during the period of agricultural dominance of the last 200 years average between 2 and 20 mm yr 1 with short episodes of even higher rates during times of particularly poor land conservation practices significant hydrologic effects of mining and agricultural started by the 1820s and became widespread in the study region by the mid 19th century the hydrologic and geomorphic influences of mining were relatively minor compared to those related to agriculture high resolution dating of floodplain vertical accretion deposits shows that large floods have frequently provided major increments of sedimentation on floodplains of tributaries and the main valley upper mississippi river the relative importance of large floods as contributors to floodplain vertical accretion is noteworthy because global atmospheric circulation models indicate that the main channel upper mississippi river should experience increased frequencies of extreme hydrologic events including large floods with anticipated continued global warming instrumental and stratigraphic records show that coincident with global warming a shift to more frequent large floods occurred since 1950 on the upper mississippi river and these floods generally contributed high magnitudes of floodplain sedimentation

land use changes and longer term human environment interactions in a mountain region sudetes mountains poland abstract long term socio economic changes in the mountain communities best documented as land use changes have been reflected in alternating functioning of the environmental system in the upper valleys in the sudetes mountains the main role that human activity played on morphogenetic processes was to intensify or to weaken the linkages between hillslope and river systems all stages of environmental change as a result of increasing or decreasing human impact are easily recognisable in the area both as human made landforms and as sediment records therefore they provide archives of past and present human activities allowing for the reconstruction of morphogenetic processes in the past detailed sedimentological and geomorphological analyses along with studies on archival documents topographic maps and aerial photographs from various periods reveal many local variations even within one small drainage basin occasionally human impact might be of the same type and intensity in the entire catchment but coeval environmental records for example the thickness of colluvial or alluvial sediments may differ substantially the role of local topography hillslope and valley length hillslope gradient and microrelief etc considerably influences sediment transfer and depositional processes hillslope channel coupling is of importance as only in some places transport and sediment export from the catchment was favoured in other places local topographic conditions favoured sediment storage limiting transport distance human impact turned out to be more important and much more widespread than previously assumed despite fewer human induced sediments in the upper valley reaches these are actually better archives for reconstructing the linkages between land use changes and hillslope and channel response small size catchments in the upstream parts of the study area are therefore suitable areas for reconstructing assessing and quantifying past morphological human environment interactions

response of small mid mountain rivers to human impact with particular reference to the last 200 years eastern sudetes central europe abstract in the mid mountains of central europe relict forms of periglacial morphogenesis occur including debris slope covers however the holocene forest succession limited sediment transfer towards valley systems the eastern mid mountain part of the sudetes characterised by a dense stream network and by the local occurrence of metallic and gold ores was already settled by humans in early medieval times timber from the forested slopes was used to produce charcoal and streams acted as energy sources for smelting plants and smithies agriculture developed on less inclined slopes temporal clearances on steep slopes and replacement of primeval beech forest by spruce trees influenced water circulation on slopes the exposed slope covers were transferred to valley floors during high precipitation events consequently they were selectively redeposited within the floodplain changing the former channel pattern especially at confluences the introduction of cultivation on slopes triggered intense soil erosion so that agricultural terraces were built in order to prevent surface wash the terraces are often strengthened with stone walls up to 4 5 m high terraces acted as sediment traps storing the washed material within the slope the layers of fine grained colluvial sediments which can be linked with agriculture cover the older debris slope covers the colluvium is especially thick at the terrace edges despite the protective role of terracing part of the washed material was transferred to valleys often becoming overbank deposits covering older gravel and boulder alluvium the decline of iron ore exploitation and processing at the beginning of the 19th century together with agricultural withdrawal which was especially radical after the 2nd world war resulted in successive renaturalisation of the environment being followed by slope stabilisation and deepening of bigger river channels the results led to the conclusion that a strong human impact on the slope valley system in the mid mountain part of the eastern sudetes influenced changes in the dynamics and morphology of small rivers to a much higher extent than the climate variations especially during the little ice age

sediment yield and storage variations in the negron river catchment south western parisian basin france during the holocene period in the negron river catchment area 162 km2 surface sediment stores are composed of periglacial calcareous greze 5 106 t and loess 21 106 t and holocene alluvium 12 6 106 t peat 0 6 106 t and colluvium 18 5 106 t seventy five per cent of the holocene sediments is stored along the thalwegs present net sediment yield calculated from solid discharge at the negron outlet is low 0 6 t km 2 a 1 due to the dominance of carbonate rocks in the catchment mean sediment yield during the holocene period is 7 0 t km 2 a 1 from alluvium stores and 7 6 t km 2 a 1 from colluvium stores thus the gross sediment yield during the holocene period is about 18 7 t km 2 a 1 and the sediment delivery ratio 3 per cent the yield considerably varies from one sub basin to another 3 9 to 24 5 t km 2 a 1 according to lithology about 25 per cent and 50 per cent of initial stores of periglacial greze and loess respectively were reworked during the holocene period sediment yield has increased by a factor of 6 in the last 1000 years due to the development of agriculture the very high rate of sediment storage on the slope during that period 88 per cent of the yield can be accounted for by the formation of cultivation steps rideaux it is predicted that the current destruction of these steps will result in a sediment wave reaching the valley floors in the coming decades subboreal and subatlantic sediments and pollen assemblages in the taligny marsh where one third of the alluvium is stored show the predominant influence of human activity during these periods in the negron catchment copyright 2002 john wiley sons ltd

fluvial processes morphology and sediment budgets in the coon creek basin wi usa 1975 1993 sediment budget processes in coon creek wisconsin from 1975 to 1993 changed only moderately generally continuing the trends that were evident in 1975 perhaps most importantly sediment yield to the mississippi river appears to be unabated with much of this clearly coming from storage loss especially stream bank erosion vertical accretion continued on the lower new floodplains inset within their meander plains in tributaries and the upper main valley the lower main valley also continued to aggrade but at the rate of about 6 of that occurring in the 1920s and 1930s the major revision from earlier studies is that the upper main valley is a less significant net source of sediment than previously thought and the earlier prognostications of it being a significant net source of sediment in the future may be wrong perturbations have been caused by changes of riparian vegetation and much more importantly by the introduction of fish shelter structures and protected cut banks along the stream system reaching downstream to the end of the upper main valley because these structures do not permit natural stream migration bank erosion and downstream sediment transfer the coon creek basin has lost much of its suitability as a natural laboratory of fluvial processes

reconstruction of late holocene slope and dry valley sediment dynamics in a belgian loess environment to unravel the evolution of a dry valley in the belgian loess area soils and sediments along a slope catena were studied in detail a 67 m long trench was opened from the upper slope to the centre of the valley bottom the exposed soils and sediments showed evidence of severe soil erosion and other human disturbances that significantly changed the valley topography the early holocene slope gradient was up to 25 whereas now it is less than 10 in the thalweg a remnant of the early holocene soil was found underneath colluvial deposits which were more than 3 m thick a chronology for the valley evolution was established based on ams 14c dating of charcoal fragments and optical dating of colluvial sediments the first sediment deposition occurred in the early iron age with an average sedimentation rate of approximately 3 4 1 3 t ha per yr this increased to c 5 4 2 2 t ha per yr during the roman period and further to 18 0 2 2 t ha per yr in the middle ages although sediment accumulation in the

the history of soil erosion and fluvial deposits in small catchments of central europe deciphering the long term interaction between humans and the environment a review abstract during the last few decades many case studies focused on the dynamics of fluvial systems in response to hillslope erosion land use impact and climate changes this paper will review the current state of knowledge of the dynamics of past soil erosion and gullying in small catchments

holocene history of the river seine paris france bio chronostratigraphic and geomorphological evidence from the quai branly bio chronostratigraphic observations compiled from quai branly in paris france and their comparison with previous studies in the paris basin allow documentation of the morphodynamic evolution of the river seine during the middle and late holocene this history begins in the boreal between 9500 and 8850 cal bp with the deposition of tufa expressing a stabilized river bed during the second part of the sub boreal the water table was low at the beginning of the sub atlantic towards 2800 2700 cal bp alluvial dynamics increase as is recorded elsewhere throughout the paris basin at the beginning of the second part of the sub atlantic around 2000 cal bp flood dynamics persisted at a lower intensity human occupation occurred from the fifth century ad before or around the beginning of the seventeenth century ad a natural levee was built indicating the progressive attachment of the quai branly area to the floodplain the hydrodynamic evolution of the river seine observed at the quai branly site is similar to that recorded in other river valley floors of the paris basin this evolution appears to be in response to global climatic changes rather than to variations induced by human activities

late quaternary landscape evolution of the upper dnister valley western ukraine abstract the broad and flat valley of the upper dnister in western ukraine is characterized by a complex setting of ecotopes and a relatively natural state of floodplain dynamics excellent geo archives extended peat bogs and postglacial river terraces document late quaternary landscape evolution with special regard to changes in fluvial morphodynamics vegetation and human impact the terraces were studied by detailed geomorphological mapping as well as sedimentological and pedological analyses in connection with information from historical maps vegetation history was studied by palynological methods in combination with radiocarbon dating two late pleistocene nt1 and nt2 and seven holocene h1 h7 river terraces are evident the ecological transformation during the period of climatic warming at the end of the last glacial maximum lgm caused the most significant change in runoff and sediment load as well as in the vegetation cover the dnister changed from a braided to a meandering river system it was soon after the spreading of postglacial forests with an increasing dominance of broadleaved trees that the pollen diagrams reflected the first signs of anthropogene influence intensified agricultural land use since the iron age is mirrored in the increasing amount of herbaceous pollen as well as the rise of fluvial sediment redeposition modern hydraulic engineering on the dnister has caused visible transformations because of these impacts the stability of the upper dnister ecosystem has decreased significantly and is now highly sensitive to environmental change

effects of normal faulting on fluid flow in an ore producing hydrothermal system comstock lode nevada abstract normal faults in the comstock lode mining district nv usa are delineated by low 18o belts and strong isotopic gradients perpendicular to strike these faults perturb and also offset the regional pattern of 18o contours produced by pervasive hydrothermal alteration of the alta formation and have preserved the down dropped hanging wall rocks while exposing the footwall rocks to greater erosion fluid rock interaction was greatly enhanced within 200 m wide zones centered on the normal faults where permeability was increased and fluids were focused parallel to the fault plane the effects of displacement and permeability enhancement around the faults are investigated using oxygen isotope profiles through the comstock and occidental faults and across steeper secondary normal faults such as the coryell fault that may have formed after the principal faults were rotated to more shallow dips oxygen isotope profiles record both post hydrothermal displacement and syn deformational enhancement of fluid flow around the faults fluid focusing along normal faults perturbs the 18o values by increasing the water rock ratio this isotopic effect can be mathematically described for any distance x from the fault using the formula f a e bx 2 which is analogous to the fundamental solution for diffusion away from a plane source the maximum magnitude of 18o depletion a depends on the effects of permeability temperature mineralogy fluid isotopic composition and integrated fluid flux the constant b is related to the scale of exchange enhancement around the fault the characteristic width w 1 b of the fluid focusing effects is remarkably similar at 100 m for all three faults examined coupling this isotope exchange effect with a step function which accounts for fault displacement provides a good fit to the observed 18o fault profiles the 18o distribution around faults can be used to infer relationships and timing among the processes of structural deformation hydrothermal convection and ore deposition in the comstock district

the temperature of europe during the holocene reconstructed from pollen data we present the first area average time series reconstructions of warmest month coldest month and mean annual surface air temperatures across europe during the last 12 000 years these series are based on quantitative pollen climate reconstructions from over 500 pollen sites assimilated using an innovative four dimensional gridding procedure this approach combines three dimensional spatial gridding with a fourth dimension represented by time allowing data from irregular time series to be focussed onto a regular time step we provide six regional reconstructed temperature time series as well as summary time series for the whole of europe the results suggest major spatial and seasonal differences in holocene temperature trends within a remarkably balanced regional and annual energy budget the traditional mid holocene thermal maximum is observed only over northern europe and principally during the summer this warming was balanced by a mid holocene cooling over southern europe whilst central europe occupied an intermediary position changes in annual mean temperatures for europe as a whole suggest an almost linear increase in thermal budget up to 7800 bp followed by stable conditions for the remainder of the holocene this early holocene warming and later equilibrium has been mainly modulated by increasing winter temperatures in the west which have continued to rise at a progressively decreasing rate up to the present day

proxy climate record for the last 1000 years from irish blanket peat and a possible link to solar variability recent research has shown that ombrotrophic mires can yield a proxy climate signal based on changes in the degree of peat humification 1 2 and that oceanic margin sites show the most sensitive record 3 we compare humification records for the last 1000 yr from two radiocarbon dated blanket peat profiles from western ireland and show several corresponding periods of climatic fluctuations periods favouring reduced peat decomposition suggestive of wetter and or cooler climatic conditions seem to coincide with periods of reduced sunspot activity and atmospheric14c anomalies whilst climatologists have continued to debate a link between solar variability on a century timescale and climate change the exact nature of that link remains elusive 4 7 the results from ireland demonstrate that data derived from mires could be relevant to the debate as to the extent of solar forcing in natural climatic variability and the curves shown provide a continuous record to add to previous evidence for the so called medieval optimum and little ice age 8 the record may imply that during the past millennium climatic change at the oceanic margin of the northeast atlantic largely corresponded to inferred variations in solar output

the impact of land use and climate change on late holocene and future suspended sediment yield of the meuse catchment abstract in this study we investigate the relative importance of changes in land use and climate on suspended sediment yield sy on millennial timescales in the meuse basin we use a spatially distributed soil erosion and sediment delivery model watem sedem to simulate sy in three time periods 4000 3000 bp minimal anthropogenic influence 1000 2000 ad includes land use and climate change and the 21st century changes in climate are based on climate model output ecbilt clio vecode for the 21st century the model is forced according to two emission scenarios of the intergovernmental panel on climate change ipcc namely the sres scenarios a2 and b1 these scenarios lie towards the higher and lower end of the full ipcc scenario range respectively for 4000 3000 bp the basin is assumed to be almost fully forested for 1000 2000 ad land use is reconstructed using corine data historical sources and land use modelling and for the 21st century land use is based on the european land use change project eururalis whilst rainfall erosivity increases by only 3 between 4000 3000 bp and 1000 2000 ad sy increases from ca 92 000 mg a 1 to ca 306 000 mg a 1 this model prediction is in agreement with the limited regional multi proxy data available our simulations show that almost all of this increase is due to the conversion of forest to agricultural land over the period 1000 1900 ad sy shows a significant increasing trend with a peak of ca 388 000 mg a 1 in the 19th century due to continuing deforestation in the 20th century reforestation and rapid urbanisation result in a decrease to ca 281 000 mg a 1 sensitivity analyses show that although land use change acts as the primary control on long term changes in sy the sensitivity of sy to changes in climate increases as the percentage of deforested land increases for the 21st century the results are highly sensitive to the scenarios used due to relatively large increases in rainfall erosivity sy increases by 12 compared to the 20th century according to scenario a2 or by 8 according to b1 however the associated land use change scenarios cause decreases in sy by 26 a2 and 46 b1 the net effect is thus a decrease of sy this study highlights the potentially significant efficacy of land use planning as a tool to mitigate the negative effects of soil erosion and sediment delivery to rivers

evidence for climatic deteriorations associated with the decline of sphagnum imbricatum hornsch ex russ in six ombrotrophic mires from northern england and the scottish borders the decline of sphagnum imbricatum from the peat stratigraphy of six ombrotrophic mires bolton fell moss and walton moss raeburn flow and bell s flow and coom rigg moss and felecia moss has been investigated using colorimetric humification quantitative plant macrofossil and testate amoebae analyses the chronology of each peat profile was determined by radiocarbon assay and pollen land use correlations palaeoclimate reconstructions have been made by linking known documentary historical changes in climate and other proxy climate records to those inferred from the sites investigated in the study region in two of the ombrotrophic mires examined there are wet shifts associated with the decline and local extinction of s imbricatum which are dated to cal ad 1160 1400 raeburn flow and bell s flow in coom rigg moss and felecia moss wet shifts are also associated with the decline and local extinction of s imbricatum between cal ad 1395 1485 the decline of s imbricatum from two other ombrotro

timescales climate and river development abstract in the long term glacial interglacial sequences river development follows general climatic evolution however at the scale of one cold warm cycle it appears that the geomorphological effect of river activity is best expressed at times of climatic change such periods of pronounced fluvial action last only a short time in more detail the internal evolution in a drainage basin after a climatic event results in a delayed response of the morphology and sedimentation pattern finally on the shortest timescale local thresholds may play a decisive role in the reactions of river systems it is concluded that the relation between fluvial development and climate is not a simple one but is fundamentally dependant on the timescale

the black floodplain soil in the amoneburger becken germany a lower holocene marker horizon and indicator of an upper atlantic to subboreal dry period in central europe abstract in many sediment profiles of central european floodplains a black horizon is found between late glacial and middle to upper holocene sediments this horizon is rich in clay and humic material and is referred to as black floodplain soil bfs its widespread occurrence in the amoneburger becken near marburg hessen provides some new insights into the period and circumstances of its development as a polygenetic formation the bfs is of special importance for paleoecological and archeological research it was probably supplied with clay and humic substances from the surrounding terrestrial chernozemic soils and therefore it also has to be regarded as a sediment it developed mainly in the boreal and atlantic periods but did not gain its final characteristics until a following dry period which led to a lowering of the ground water table and widespread illuviation in the floodplains even in former lacustrine deposits

european lakes as palaeohydrological and palaeoclimatic indicators abstract lakes in temperate regions have fluctuated in size on annual to millenial time scales changes in water level or depth can be reconstructed by applying geomorphic sedimentological and biostratigraphic methods to transects of sediment cores this systematic field based approach has been used at a number of sites in europe it is illustrated by reconstructions of water level changes in lakes from southern sweden these lakes have shown broadly synchronous changes during the holocene such synchronous changes in water levels at several sites in a region reflect climatic changes inferences about the mechanism of the climatic change depend on identifying both synchronous changes within a region and differences in the direction magnitude and timing of lake level changes between regions continental compilations of lake level data are therefore necessary detailed studies are not available from enough sites but the interpretation of already existing stratigraphic and biostratigraphic data in terms of lake level changes has greatly increased the number of sites available for a continental scale synthesis in europe this eclectic literature based approach is illustrated with examples from southern europe lakes in the mediterranean region were high around the glacial maximum and again somtime during the first half of the holocene in the western mediterranean the peak of late glacial aridity occurred at 15 000 16 000 bp and the lakes were already high again by 12 000 bp in the east maximum late glacial aridity occurred between 13 000 and 11 000 bp and there was a gradual return to wetter climates during the early holocene such that 9000 bp was more arid than 6000 bp most lakes in the mediterranean region were high at 6000 bp the transition to arid conditions after 5000 bp occurred abruptly in the west and more gradually in the east the lakes of southern sweden indicate drier climates in the early holocene ca 9000 bp more effective moisture between 8000 and 6000 bp increased aridity between 5500 and 3500 bp and increased effective moisture again during the last 3000 years the history of lake level changes in southern sweden and the mediterranean region can be partially explained in terms of changes in the direct effects of insolation and in the strength and position of the westerlies and of the subtropical high pressure cell during the late quaternary

holocene river activity analysing 14c dated fluvial and colluvial sediments from germany records of fluvial dynamics in response to long term changes of climate and land use impacts are rare therefore cumulative probability functions cpfs of 401 14c ages originating from german rivers and hillslopes were compiled to reconstruct phases of increased geomorphic activity and stability during the holocene an improved analytical method is suggested to normalise cpfs and eliminated the effects of wiggles of the calibration curve and the young age bias nine periods of activity are identified peaking at 7050 6250 5525 3690 2250 1350 820 325 bc and since 875 ad and are compared with climatic palaeohydrological and human impact proxy data until 2250 bc events of geomorphic activity are mainly coupled to wetter and or cooler climatic phases due to growing population and intensive agricultural activities during the bronze age the increased geomorphologic activity between 1300 and 820 bc cannot unequivocally be related to climate since 875 ad the growing population density is considered as the major external forcing differential geomorphic activity of hillslopes and floodplains suggest that the hillslope channel coupling during the holocene is mainly controlled by human impact with a strong increased coupling after 1500 bc

human and climate impact on catchment development during the holocene geul river the netherlands interest in the holocene development of small to medium sized river catchments in western and central europe in relation to changes in land use and climate has increased over the past years in this study we reconstruct the holocene landscape development and fluvial dynamics of the geul river the netherlands and the main forcing mechanisms of environmental change field studies were carried out and we used osl and 14c dating methods to reconstruct the holocene valley development our study shows that 2 periods of deforestation during the roman period and the high middle ages led to severe soil erosion and increased floodplain sedimentation in the catchment of the geul river possibly combined with periods of increased wetness during the high middle ages alluvial fans have been active since the roman deforestation phase our results show that the geul catchment is highly sensitive to changes in land use