geoelectric investigations of a fault system in quaternary deposits geoelectric soundings were used to investigate the younger fault activity middle and early pleistocene of the southwestern fault margin area of the central graben and extension of the rhine graben in the southern netherlands and northern belgium some effects of this fault activity can still be observed in the present geomorphology and hydrography investigations have been concentrated on the uppermost 20 30 m consisting mainly of middle and early pleistocene fluviatile deposits marshy clays and loams are most conductive they alternate with large sand beds and gravelly gully infillings characterized by high specific resistivities problems in the interpretation of the geoelectric data caused by the variability of the deposits are partially solved by in situ resistivity measurements mini electric measurements in spite of the lithologic inhomogeneity a few marker horizons allow the geologic structure to be determined some new tectonic boundaries have been traced the movements along the faults during the quaternary are very small less than 10 m therefore the network of soundings has to be very dense and a very intensive analysis of the soundings is necessary the results also have a hydrogeologic significance this project illustrates the possibility of locating small tectonic structures in relatively inhomogeneous deposits by a detailed and carefully designed geoelectric survey

age limits on the late quaternary evolution of the upper loire river abstract the loire river is one of the largest rivers in europe draining a basin area of southern france which exceeds 100 000 km 2 despite its significance the loire remains poorly studied and has a very limited amount of chronological control on the deposited sedimentary record of fluvial activity these factors coupled with the availability of a set of 10 radiocarbon dates on younger c

fluvial response to climate change during and after the last glacial maximum in central anatolia turkey abstract fluvial response to climate change during and after the last glacial maximum lgm included incision aggradation phases recorded in sediment cores from the valley floor of the kizilirmak in central anatolia a numerical chronology was established by ams dating of fluvial sediments and ar ar dating of a basalt sample capping the youngest terrace late pleistocene terrace indicating that the main incision phase was completed at the end of the lgm the succeeding aggradation phase in the valley took place from the end of the lgm onwards it appears that the major climatic transition from the lgm to the late glacial gave rise to aggradation in the fluvial system and this event seems to be consistent with the timing of the regression phase of pluvial lakes and the termination of paleoglacier advances in the high mountains of anatolia this study of fluvial systems in anatolia indicates that the coldest periods are not always characterized by fluvial aggradation

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

how old are young lunar craters 1 the accurate definition of the lunar cratering chronology is important for deriving absolute model ages across the lunar surface and throughout the solar system images from the lunar reconnaissance orbiter narrow angle cameras and wide angle camera and the selene kaguya terrain camera provide new opportunities to investigate crater size frequency distributions csfds on individual geological units at lunar impact craters we report new csfd measurements for the copernican aged craters north ray tycho and copernicus which are crucial anchor points for the lunar cratering chronology we also discuss possible reasons for an age discrepancy observed between the impact melt and ejecta units our csfds for north ray and tycho crater ejecta deposits are consistent with earlier measurements however for copernicus crater and one of its rays we find significantly lower cumulative crater frequencies than previous studies our new results for copernicus crater fit the existing lunar absolute chronologies significantly better than the previous counts our derived model ages of the ejecta blankets of north ray tycho and copernicus agree well with radiometric and exposure ages of the apollo 16 17 and 12 landing sites respectively and are generally consistent with a constant impact rate over the last 3 ga however small variations of the impact rate cannot be resolved in our data and require further investigations

western mediterranean environmental changes evidences from fluvial archives abstract when dealing with current and past landscape evolution a key issue addresses responses of geomorphic systems to the large number of influencing variables identifying morphodynamic phases and revealing interrelations with specific driving forces are demanding tasks for quaternary research in this paper we present late pleistocene and holocene fluvial sedimentation patterns of three western mediterranean river catchments namely jarama river guadalete river and guadalquivir river that extent along a climatic transect from semi humid sw spain to semi arid central spain these studies are based on extensive fieldwork conducted on 36 exposures and 13 drillings in floodplain positions field data is supported by geochemical analyses while the chronological framework was obtained from the analyses of 70 radiocarbon samples results show distinct patterns of fluvial sedimentation as well as soil formation linked to floodplain stability for each river catchment on regional or catchment scale pollen stratigraphical correlation and comparison with lacustrine records show that fluvial dynamics have a strong reaction to climatic shifts with phases of high fragility characterized by catchment erosion and floodplain sedimentation in response to climatic aridification events and phases of climate change in general the comparison of the examined river systems reveals that periods of supra regional floodplain sedimentation in several catchments occurred from 8 0 to 7 0 5 0 to 3 8 2 2 to 1 5 and around 1 0 as well as 0 4 ka cal bp while we found periods of supra regional soil formation from 13 3 to 12 7 7 0 to 5 1 with a short interruption around 6 0 to 5 5 ka 2 8 to 2 3 ka 1 4 to 1 2 ka and 0 8 to 0 5 ka cal bp beside these consistencies we found deviating dynamic patterns that are apparently expressed in terms of differing onset and offset differing durations or even the lack of fluvial system response the main reasons for this can be seen in different regional climate condition and impacts of further influencing factors or in different levels of sensitivity of the river catchments that may be controlled by initial hydrological conditions catchment size or the degree of anthropogenic influence a larger scale assessment shows that fluvial dynamic patterns are hardly comparable across entire spain due to strong spatial heterogeneity of physiographic and climatic conditions on the iberian peninsula in particular when areas are influenced by different circulation systems e g regions influenced by the atlantic ocean vs regions influenced by the mediterranean sea however the consideration of north atlantic marine records reveals a certain coupling between north atlantic coolings atmospheric processes leading to arid climate over large parts of spain as well as increased landscape instability including strong fluvial sedimentation activity attendant atmospheric conditions are discussed

theoretical regime equations for mobile gravel bed rivers with stable banks a system of rational regime equations is developed for gravel bed rivers with stable banks using the optimality theory ot the optimality theory is based on the premise that equilibrium river geometry is characterised by an optimum configuration defined here as maximum sediment transport efficiency theoretical dimensionless equations are derived for width depth slope width depth ratio and meandering braiding transition independent dimensionless variables comprise discharge sediment concentration and relative bank strength which is defined as the ratio of the critical shear stresses for the bank and bed sediments discharge exponents and general form of the equations agree well with previously developed empirical relations relative bank strength is used to parameterise the influence of riparian vegetation on bank strength and is evaluated by calibrating against observed width depth ratio once calibrated the hydraulic geometry of natural gravel rivers is well described by the theoretical equations including discrimination between meandering and braiding channels the results provide strong support for the assumption that equilibrium or regime river behavior is equivalent to an optimal state and underline the importance of bank strength and sediment load as controls on hydraulic geometry

stability of composite river banks the stability of a river bank depends on the balance of forces motive and resistive associated with the most critical mechanism of failure many mechanisms are possible and the likelihood of failure occurring by any particular one depends on the size geometry and structure of the bank the engineering properties of the bank material the hydraulics of flow in the adjacent channel and climatic conditions rivers flowing through alluvial deposits often have a composite structure of cohesionless sand and gravel overlain by cohesive silt clay bank erosion occurs by fluvial entrainment of material from the lower cohesionless bank at a much higher rate than material from the upper cohesive bank this leads to undermining that produces cantilevers of cohesive material upper bank retreat takes place predominantly by the failure of these cantilevers three mechanisms of failure have been identified shear beam and tensile failure the stability of a cantilever may be analysed using static equilibrium and beam theory and dimensionless charts for cantilever stability constructed application of the charts requires only a few simple measurements of cantilever geometry and soil properties in this analysis the effects of cracks and fissures in the soil must be taken into account these cracks seriously weaken the soil and can invalidate a stability analysis by affecting the shape of the failure surface following mechanical failure blocks of soil must be removed from the basal area by fluvial entrainment if rapid undermining and cantilever generation are to continue hence the rate of bank retreat is fluvially controlled even though the mechanism of failure of the upper bank is not directly fluvial in nature this cycle of bank erosion undermining cantilever failure and fluvial scour of the toe operates over several flood events and has important implications for river engineering channel changes and the movement of sediment through fluvial systems

palaeoflood and floodplain records from spain evidence for long term climate variability and environmental changes abstract palaeoflood chronologies from seven spanish river basins and floodplain aggradation chronologies from thirteen rivers are analysed these fluvial records were divided in to two sub sets namely atlantic 10 ka record and mediterranean 3 ka record river basins which represent distinct modern hydroclimatic conditions in atlantic basins floods result from intense widespread rainfalls associated with atlantic frontal systems transported by westerly airflow mediterranean river flooding is related to heavy rainfall induced by mesoscale convective systems mcss during autumn months evidence from radiocarbon dates in slackwater flood deposits shows six periods of flood clusters at 10 750 10 240 9550 9130 4820 4440 2865 2350 960 790 and 520 290 cal bp despite the different flood producing weather conditions in atlantic and mediterranean rivers the radiocarbon sample clusters overlap and indicate changes in large scale atmospheric circulation and climatic conditions in the iberian peninsula comparison with proxy records of mean temperature for the northern hemisphere demonstrates a relationship between the period of slackwater flood deposition and cold climatic phases e g the 2650 yr bp climatic event or ad 1590 1650 period of the little ice age radiocarbon dates from aggraded floodplain sediments were clustered at 2710 2320 2000 1830 and 910 500 cal bp the first cluster period is in phase with the timing of slackwater deposition whereas the third 910 500 cal bp occurs in between two periods of increased flood frequency as indicated by the palaeoflood and documentary flood records it is argued that the 910 500 cal bp floodplain aggradation period reflects the first post roman evidence of environmental change related to generalised land use changes at the catchment scale which produced high sediment load transported to overbank areas during high flows

fluvial changes of the guadalquivir river during the holocene in cordoba southern spain this research was funded by a grant from proyectos de cordoba siglo xxi coordinated by prof r jose roldan canas universidad de cordoba

channel adjustments in the lower guadalquivir river southern spain over the last 250 years abstract the lower guadalquivir river has been subjected to a series of channel adjustments over the last 250 years mainly in response to human factors and disturbances from 1778 to 1918 the results show an oscillation in the sinuosity along the upstream segment and a reduction along the downstream segment in response to artificial cut offs the first phase of incision started in approximately the 1840s 1850s following a previous phase of predominant aggradation probably related to abundant sediment supply caused by deforestation in the catchment during approximately the last 100 years notable incision and progressive channel narrowing occurred in both segments although secondary aggradation upstream of the dams and widening in a portion of the downstream segment were also observed the first phase of bed incision migrating upstream is interpreted as a consequence of artificial meander cut offs whereas most of the adjustments that occurred during the last 100 years are interpreted as a consequence of the large number of dams in the catchment and along the studied area which caused a notable deficit in bedload

enhancing rescue archaeology using geomorphological approaches archaeological sites in paredes asturias nw spain abstract palaeolithic remnants a necropolis roman villa and another minor archaeological site were discovered in paredes spain these sites were the focus of multidisciplinary research during the construction of a large shopping centre in asturias nw spain the aims of this study are 1 to contribute to archaeological prospection in the sites and 2 to develop evolutionary models of the sites based on geomorphological inferences detailed archaeological prospection 103 trenches geomorphologic mapping stratigraphic studies 36 logs and ground penetration radar gpr surveys on five profiles indicate that the location of the settlement source of the necropolis is outside the construction perimeter farther to the southeast the pre holocene evolution of the fluvial landscape is marked by the development of two terraces t1 and t2 that host the early palaeolithic remains in the area ca 128 71 ka the holocene evolution of the landscape was marked by the emplacement of the nora river flood plain covered by alluvial fans after ca 9 ka bp cal bc 8252 7787 subsequently neolithic pebble pits dated ca 5 3 ka bp cal bc 4261 3963 and 4372 4051 were constructed on t2 at the area reoccupied as a necropolis during the late roman period 1590 45 years bp cal ad 382 576 coeval human activity during the late roman period at 1670 60 years bp cal ad 320 430 is also recorded by channel infill sediments in a minor site at the margin of an alluvial fan located to the southeast this work shows that a rescue archaeological study can be significantly enhanced by the implementation of multidisciplinary scientific studies in which the holistic view of geomorphologic settings provide key insights into the geometry and evolution of archaeological sites

the relation between climate and river processes landforms and deposits during the quaternary abstract the extent to which river processes and morphology are dependent on climate is an old question when looking at large time scales climatic cyclicity seems to coincide with alternating events in fluvial development however the shorter the time scales at which fluvial development is considered the more it is difficult to find a close correspondence with climate evolution ultimately it appears that the response time of river processes to climatic change may restrict the sensitivity of the fluvial systems to adapt to short climatic oscillations the impact of climate on fluvial systems is largely transferred to these systems by the climate determined soil cohesion and peak discharges the latter factors are especially related to vegetation cover and permafrost conditions finally a number of basin characteristics are discussed that demonstrate that fluvial systems are not completely controlled by climate

hydraulic geometry of cohesive channels undergoing base level drop abstract this study extends earlier contributions on dynamic adjustments of fluvial channels to base level changes we have investigated an in situ response of self formed cohesive channels to a base level drop conditions analogous to a gradual change in uplift and or climate empirical hydraulic geometry equations for clayey cohesive natural streams are presented using data from eight channels draining perennial brackish springs and discharge into the dead sea investigation of downstream variations in gradient and stream power relations suggests existence of three distinct reaches in which channel adjustment to base level drop is shared inequitably among hydraulic geometry variables values of the flow velocity exponent m are low 0 11 m 0 24 the mid channel reach having the lowest exponent the depth exponent f has the lowest value f 0 3 for the uppermost channel reaches the rest having higher values f 0 4 the smallest width exponent b 0 35 characterizes the upper reaches these values and their spatial distribution exhibit a regular pattern we show that the lowermost channel reach adjusts by profile steepening and channel narrowing f b the prevailing mechanism in the mid channel reaches is lateral width adjustment cross sections transiently transforming toward equilibrium the uppermost reaches have wide and shallow channel cross sections because of series of bank collapses and resultant sediment aggradation bringing rise to decreased local gradient forcing further channel widening the results of this study not only allow inference about how cohesive channels regulate their geometry but also reveal the means by which hydraulic forces overcome substrate resistance adjusting slope and channel dimensions and as such have implication for reach scale channel morphology and models of stream power

periglacial fluvial systems in northwest europe during marine isotope stages 4 and 3 comparison of fluvial successions in river valleys dating from marine isotope mi stages 4 and 3 in a west east transect from britain to poland shows the spatial and temporal variation in palaeohydrological characteristics of northwest european river valleys during these stages mi stage 4 has been a period of deep fluvial incision following this erosion most valleys were filled during mi stage 3 with successions of gravelly river deposits britain or sand silt peat successions northwest european lowlands the sedimentology of the deposits suggests strong discharge variations caused by a nival discharge regime with pronounced spring snowmelt discharges the mi stage 3 climate oscillations generally cannot be traced in the fluvial record an incision phase of hengelo interstadial age has been found in the netherlands but similar incision phases related to other warming events have not been proved convincingly the restricted reaction of the river systems is caused by the absence of geomorphologically effective vegetation changes and relatively minor variations in precipitation during mi stage 3 over longer time scales silt and peat beds gradually decrease in the younger post hengelo upton warren part of mi stage 3 corresponding with evidence of aeolian activity and permafrost this is related to the longer duration of the stadials in this part of mi stage 3

the flickering switch of late pleistocene climate change polar ice contains a unique record of past climate variations previous greenland ice cores have documented relatively warm interstadial periods during the last glaciation and short centuryscale returns to colder conditions during the glacial to interglacial warming see for example ref 1 these climate features have also been observed to varying degrees in ocean sediment cores2 4 and terrestrial pollen and insect records5 7 here we report electrical conductivity measurements from a new greenland ice core which confirm these previous observations and also reveal a hitherto unrecognized mode of rapid climate variation fluctuations in ice conductivity on the scales of 5 20 years reflect rapid oscillations in the dust content of the atmosphere this flickering between two preferred states would seem to require extremely rapid reorganizations in atmospheric circulation

predicting downstream hydraulic geometry a test of rational regime theory 1 the classical equations of hydraulic geometry are purely empirical but the widespread similarity of the scaling downstream form of them suggests that they express some important underlying regularities in the morphology of stream channels through the drainage network a successful physical theory of river regime must be able to reproduce and explain this regularity in this paper we test the regime theory of eaton et al 2004 using selected data of hydraulic geometry we first use data from environments in which bank strength presumably does not vary greatly such as in anabranched channel systems and deltas regime models parameterized by assuming uniform relative bank strength plausibly describe the observed bankfull channel geometries in these systems we then test a modified bank strength formulation for vegetated gravel bed rivers against downstream hydraulic geometry data sets in which relative bank strength is supposed to vary with channel scale assuming a uniform effective cohesion due to riparian vegetation the regime model is again able to reproduce details of the channel geometry both analyses show that the classical hydraulic geometry represents only an approximation of the variation of channel form if we have confidence in the theory we may infer information about bank strength and bed material transport the pattern of variation in these quantities as well as discharge through the drainage system lends approximate regularity to stream channel scaling that is summarized in the empirical relations

the holocene fluvial chronology of spain evidence from a newly compiled radiocarbon database abstract a critical analysis of 74 radiocarbon dates selected from a total of 102 published and unpublished dates from holocene fluvial environments in spain has identified a number of periods of increased fluvial activity in spain namely 11 170 10 230 9630 8785 7980 6860 5800 4800 3880 3085 2895 1820 1300 0 cal bp the latter period reflecting sustained fluvial response to increased human impact the radiocarbon samples were classified according to type of depositional environment a alluvial overbank b flood basin c alluvial channel gravels d fluvio torrential deposits and e slackwater flood deposits palaeofloods dates from slackwater flood deposits indicated at least five phases of increased frequency of large magnitude floods during the holocene 10 855 10 230 9530 8780 2880 2430 975 790 and 520 265 cal yr bp flood basin type deposition occurred from 7980 to 4830 cal yr bp the main clusters of dates from alluvial floodplain deposits occurred at 2750 2150 and 930 520 cal yr bp the record is discussed in relation to other palaeoenvironmental archives including pollen records of holocene vegetation change and palaeoclimatic proxies such as the north atlantic drift ice record comparison with the latter indicates that major holocene flooding coincided with cold climate phases during 9530 9280 2880 2430 and 520 265 cal yr bp a cooling phase at 10 855 10 230 and warming phases at 9030 8780 and 975 790 cal yr bp

geomorphological evolution of a lowland valley system during the weichselian weichselian geomorphological and fluvial evolution has been recorded in the valley fill of the reusel a small tributary of the lower maas river it has been studied by means of borehole sections a first deep incision into the substratum occurred during the early weichselian lower pleniglacial this was followed by aggradation at first by a braided river at a later date by a meandering river dating respectively from the lower and middle pleniglacial the upper pleniglacial aggradation again points to a braided river system the end of the pleniglacial is characterized by aeolian infilling of the valley and decreasing carrying capacity of the river

changing river styles in response to weichselian climate changes in the vecht valley eastern netherlands abstract in the vecht valley eastern netherlands distinct changes in fluvial style and erosional phases took place from the middle part pleniglacial of the last glacial to the holocene a low energetic laterally inactive river changed around 41 ka into a higher energetic river accompanied by a distinct erosional phase even higher energetic conditions occurred during the late pleniglacial when a braided river was active fluvial activity diminished in the vecht valley towards the end of the late pleniglacial as aeolian processes became much more dominant the river became confined to a much more narrow flood plain where it incised at the onset of the late glacial deposits of two kinds of river types can be recognized in the late glacial low energetic probably meandering and braided the vecht became and remained meandering during the holocene the observed fluvial changes and erosional phases are most likely the result of climatically induced changes in the water sediment discharge ratio several distinct climate changes occurred since the middle pleniglacial some of them not all are reflected by changes in fluvial styles the response of vegetation to climate changes appears to be an important factor as it determined bank and soil stability and therefore sediment supply but also evapotranspiration rates which influenced discharge characteristics a model explaining the fluvial response to climate change is presented and discussed by the example from the vecht river incision took place at the onset of a cooler period when the discharge increased before the vegetation cover was destroyed incision also occurred as a response to warmer climate conditions but with a time lag depending on the time needed to establish a vegetation cover dense enough to decrease sediment supply and increase evapotranspiration rates

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 last climatic cycles in western europe a comparison between long continuous lacustrine sequences from france and other terrestrial records abstract during the last two decades numerous studies applied to various continental deposits have highly improved the knowledge of environmental changes in western europe during the last climatic cycles here we review a set of available data and try to correlate and compare the three long lacustrine sequences from france la grande pile les echets and le velay with other west european discontinuous limnic deposits fluvial systems and l ss accumulations limnic sequences provide the best records of the last interglacial and early glacial ca 125 75 kyr allowing a clear picture of environmental changes during this interval nevertheless there are divergent interpretations on the timing and climate regime of the last interglacial during the last glacial in the north atlantic deep sea cores and greenland ice cores short term abrupt climatic fluctuations bond events dansgaard oeschger events which are poorly or partly reflected on the continent have been recognised the classical subdivision in a lower ca 75 55 kyr very cold middle ca 55 29 kyr cold and upper pleniglacial ca 29 15 kyr very cold is confirmed both by limnic and terrestrial sequences in the rhine valley north eastern france belgium and the netherlands subcontinuous l ss accumulation river systems and associated periglacial features provide quantitative climate reconstructions that are compared with those obtained from limnic sequences interstadial events may be correlated with the major warm oscillations of the grip core during the upper pleniglacial no clear vegetation changes are apparent from lacustrine pollen sequences whereas thick l ss accumulations have registered a succession of climatic changes the timing of the lateglacial warming is now well documented from rare annually laminated lake sediments

landscape instability at the end of mis 3 in western central europe evidence from a multi proxy study on a loess palaeosol sequence from the eastern lower rhine embayment germany abstract the lower rhine embayment hosts important loess palaeosol sequences lps within the western european loess belt yielding valuable information on landscape evolution and palaeoclimatic dynamics the study focusses on the palaeoenvironmental development based on a lps from the eastern shoulder of the lower rhine embayment dusseldorf grafenberg the palaeoenvironmental development within the study area is presented and discussed based on high resolution grain size analyses selected environmental magnetic parameters and geochemical analyses complemented by luminescence age estimates differences in grain size distribution gsd as well as the u ratio clearly reflect main stratigraphical units within the lps in addition the centered log ratio transformation of gsd gsd clr which is sensitive to post depositional grain size variations traces units of intensified soil formation despite no magnetic enhancement can be observed within the grafenberg lps environmental magnetic parameters combined with selected geochemical analyses sr rb provide direct information on the modification of silicates and magnetic minerals in the course of pedogenesis and diagenesis overall the grafenberg lps contributes to the understanding of environmental conditions within the lower rhine embayment particularly for the late mis 3 and the transition to mis 2 the lps reflects major shifts in the geomorphic system which are compared to palaeoenvironmental records from different archives and different geographic regions in north western europe indicating a direct relation to north atlantic climate oscillations during the last glacial period it is shown that the hesbaye unconformity at the mis 3 2 boundary is bound to an erosional event which can be traced over wide areas within the northern european loess belt

climate related river activity at the weichselian holocene transition a comparative study of the warta and maas rivers huvial systems from the dutch and polish lowlands are compared for their evolution during the weichselian deglaciation period in both regions the pleniglacial braided river pattern changed to a meandering pattern in the beginning of the lateglacial several transitional stages between braided and high sinuosity meandering systems have been recognized a difference in fluvial activity is found during the younger dryas when the maas transformed to a braided pattern while the warta maintained its meandering pattern phases of erosion and aggradation are more or less synchronous in the different river basins but their intensity may differ greatly the major characteristics of the fluvial systems are obviously a response to the general climatic evolution and related to changes in vegetation the regional differences are of minor importance and can be explained by site specific factors threshold values within the latter factors define the changes in river dynamics

spatio temporal evolution of the choisille river southern parisian basin france during the weichselian and the holocene as a record of climate trend and human activity in north western europe abstract the morpho sedimentary evolution of the choisille floodplain lowland river catchment 288 km2 a tributary of the river loire in the south western parisian basin was studied through 61 core drillings along eight transects and a geophysical survey located in four stretches of the river stretches a and b correspond to two sub catchments and stretches c and d are in the main valley sixty 14c and four osl datings were obtained and sediments were analysed on seven reference cores eight phases of evolution differing markedly from the evolution of more northern areas in the parisian basin and north western europe were identified from spatio temporal distribution of nine lithological facies the deepest incision phase 1 occurred during the first part of the weichselian followed by the deposition of a gravelly sandy unit phase 2 during the middle pleniglacial which was deeply incised phase 3 probably during the bolling from the allerod up to the last third of the boreal phase 4 sedimentation was continuously dominated by peaty deposits with no evidence of either increased hydraulic energy during the younger dryas or of incision during the lateglacial holocene transition this trend seems to reflect the specificity of the south western parisian basin climate from the late weichselian up to the end of the boreal due to the influence of the atlantic ocean compared to more northern areas where the climate was more continental the downstream incision trend during the last third of the boreal up to the subatlantic phases 5 and 6 indicates a sharp increase in precipitation and vegetation cover the lack of peaty sediments widespread in north western europe and also of precipitated carbonates frequent in the parisian basin seems to be due to local physiographic characteristics the main part of the sediment filling which is principally silty and retrograde began during the subatlantic phase 7 and 8 as a result of deforestation of the plateaux for crop farming high human induced sediment yield and storage concealed the possible impacts of climate change on fluvial dynamics lithological facies change from phase 7 to 8 can only indicate the autogenic morphological evolution of the floodplain in accretion the non univocal upstream downstream variation in the start of phase 7 shows that sediment yield varied in space and time in the catchment particularly in relation to the agricultural potential of the different areas this observation could be used to testify human induced sedimentation in other catchments

lunar regolith thickness deduced from concentric craters in the ce 5 landing area abstract lunar regolith is the layer of fragmented and unconsolidated rock material that is repeatedly stirred and overturned on the lunar surface it can provide critical information about lunar geologic processes e g impact volcanism and the space environment china s chang e 5 ce 5 mission which will be launched in 2019 will land on the lunar near side surface and return at least 2 kg of lunar regolith through surface collection and by boring a hole no

river response to variations of periglacial climate in mid latitude europe abstract the last glaciation was characterised by considerable changes in climate many european river basins reacted to these changes by initial incision and subsequent pattern change earlier research explained this by the time lag of vegetation development after a climatic change which considerably affected the sediment load however since some river basins react differently or do not react at all this model needs to be refined this paper deals with the fluvial evolution of several rivers in northern and central europe during the last glaciation and two of them the weise elster river in the leipzig area and the spree river in the niederlausitz germany are discussed in more detail the vegetation cover on the floodplain in combination with the presence of frozen ground which affects the discharge characteristics largely determines the river type nevertheless when the sequences are compared not only synchronous changes in fluvial development may be observed but also distinct differences in fluvial development by analysing the different rivers in their varying geomorphological settings it appears that grain size basin configuration and catchment size are important parameters also which can determine whether a threshold is exceeded or not

morphological and sedimentary evolution of an alluvial floodplain in an urban area geoarchaeological approaches and applications tours france urban zones on alluvial plains offer considerable geoarchaeological potential for understanding river dynamics over large time spans and their relationship with land use because of the extensive subsoil data that is available in the alluvial plain of tours lying between the loire and the cher multidisciplinary studies of the relationships between societies and environment have been conducted as part of an archaeological research programme launched in the 1960s a sedimentary database containing data for 1309 surveys has been compiled and assembled in a geographic information system to produce geostatistical models of valley bottom geomorphology the stratigraphy and chronology of alluvial filling have also been studied with information and c14 and osl dating obtained during archaeological operations taken together the results offer a new interpretation of the morphological evolution of the alluvial plain of tours from the weichselian to the present day by providing new information that either validates or invalidates previous hypotheses bedrock incision prior to the end of the weichselian upper pleniglacial coarse sedimentation during the lateglacial relative morphological stability up to the late holocene the morphological context of the first human settlements which are not concentrated on the low alluvial reliefs and the role of urbanization conditions on the present morphology of the valley floor are also presented this applied study shows the relevance of combining different methodological approaches

comment on constraints on the depth and variability of the lunar regolith by b b wilcox m s robinson p c thomas and b r hawke any permanent presence on the moon will require use of materials from the lunar regolith the surface soil layer on the moon thus knowledge of the thickness of the lunar regolith is essential it has been proposed that crater counts obtained from high sun angle photography give larger estimates of impact crater equilibrium diameters than for low sun angle photography and thus deeper estimates of lunar surface regolith than were previously made using crater morphology size of blocky rimmed craters and equilibrium diameters determined on low sun angle images the purpose of this comment is to evaluate this result as a means of resolving this important question before planning for future lunar missions is undertaken

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

paleoenvironment and stratigraphy during the last glacial in the belgian dutch border region the weichselian deposits of the flat dutch belgian coversand area are characterized by highly varying facies types the geomorphological location and the role of water during the deposition and the transportation of the original eolian sediments may fully explain the texture and sedimentary structures of the lithostratigraphic units directly deposited eolian loams and sands on the dry interfluves contrast with the same but reworked sediments in wet valleys and depressions the formation of periglacial phenomena is also dependent on the geomorphologic lithologic and hydrologic conditions the occurrence of peaty beds is restricted to wet environments without precise climatic significance the pleniglacial sequence is subdivided into early and late pleniglacial stades both characterized by partial permafrost conditions interrupted by a middle pleniglacial interstadial complex with clearly milder conditions

influence of alluvial cover and lithology on the adjustment characteristics of semi alluvial bedrock channels abstract a growing body of research has focused on evaluating the adjustment characteristics of semi alluvial channels containing proximate bedrock mixed and alluvial sections active orogens have been the focus of most empirical field based studies with comparatively less focus on semi alluvial bedrock channels located in other regions in this study we present an inventory of channel geometry data collected from semi alluvial bedrock channels in ontario and quebec canada which are not subject to tectonic uplift data were sourced from a variety of physiographic settings permitting evaluation of the influence of alluvial cover lithology and gradient on cross sectional channel form our results show no substantial difference in channel width or scaling behaviour amongst bedrock mixed and alluvial channels included in our study except for sedimentary bedrock channels virtually bare of alluvial cover that represent a uniquely wide distinct subgroup channel gradient does not appear to exhibit any observable control on channel width amongst our study rivers suggesting that sedimentary bedrock channels form a distinct subgroup because of lithology comparatively the widths of our bedrock channels formed in igneous metamorphic bedrock are comparable to the widths of mixed channels and alluvial channels for a given discharge and drainage area our findings also suggest that cross sectional adjustment of sedimentary bedrock channels is achieved through lateral erosion of the channel banks and downward erosion of the channel bed whereas cross sectional adjustment of igneous metamorphic bedrock is primarily achieved through downward erosion of the bed with limited lateral erosion of the banks

fluvial incision and channel downcutting as a response to late glacial and early holocene climate change the lower reach of the river meuse maas the netherlands detailed fieldwork and new extensive 14c dating of residual channel infillings provide data for the reconstruction of the late glacial channel downcutting and incision history of the venlo boxmeer lower reach of the river meuse maas in the southern netherlands within a period of 500 1300 yr after late glacial climatic amelioration the meuse responded to increased discharges and decreased sediment supply by adjusting the width depth ratio of its channels two main phases of channel downcutting are followed by two main phases of floodplain lowering and narrowing indicating net floodplain degradation by the fluvial system as a non linear response to late glacial and early holocene climate change some 1300 yr after initial late glacial warming channels downcut rapidly during the early bolling 13 3 12 5 kyr bp and adopted a high sinuosity meandering style channel downcutting paused around 11 9 kyr bp possibly in response to rising groundwater levels and or the older dryas cooling event between 11 9 and 11 3 kyr bp a new floodplain was formed then lateral erosion took place and initiated a first phase of 2 6 m floodplain lowering during the late allerod gradual climate deterioration during the allerod progressively broke up soils and vegetation cover from 11 3 to 10 9 kyr bp the meuse gradually adjusted to an increased ratio of sediment supply over transport capacity through higher width depth ratios main channels became shallower and adopted a low sinuosity pattern finally culminating in a braided river system during the younger dryas the final holocene warming resulted within 500 yr in renewed rapid channel downcutting by a single low sinuosity channel during the early preboreal followed by a second phase of 1 8 2 8 m floodplain lowering copyright 1999 john wiley sons ltd

erosivity of natural intact structured clay evaluation previous studies on erodibility of cohesive soil are briefly reviewed and it is concluded that experimental observations have been mainly concerned with remolded and reconsolidated or weathered cla

pleistocene fluvial terraces from northern france seine yonne somme synthesis and new results from interglacial deposits the seine yonne and somme are the main rivers draining northwestern france and flowing into the channel during pleistocene cold stages they were tributaries of the fleuve manche they are characterised by well developed stepped terrace systems showing up to 10 incision steps for the last 1 ma after 15 years of research and the synthesis of stratigraphical sedimentological bioclimatical data and numerical dating these terrace systems are interpreted as the response of the fluvial environments to climatic cyclicity superimposed on a background of slow tectonic uplift the comparison of these three terrace systems shows that the incision budget is similar within the studied area about 55 65 m 1 ma implying relative homogeneity of uplift in the main part of the area beyond marine influence the analysis of each stepped alluvial formation shows regular sediment balance generally composed of coarse periglacial gravels pleniglacial covered by fine grained sediments locally overlain by calcareous tufa interglacial however in the lower seine valley close to the present coast the low terrace includes two estuarine interglacial units interbedded within periglacial gravel units nevertheless until recently evidence of full interglacial conditions remained elusive in fluvial contexts especially in the somme to address these issues a new research programme has been launched on tufa deposits that are the best candidate to register the climatic optimum initial results from la celle seine saint acheul and caours somme allow palaeoenvironmental reconstructions of mis 11 and 5e and thus confirm the importance of calcareous tufa to define a reference record of pleistocene interglacials for northern france moreover it has been previously demonstrated that the main incision leading to terrace formation can be attributed to the transition between interglacial and glacial during early glacial phases the new results from interglacial records have important implications concerning the precise occurrence of the major incision phases within the climatic cycle as they provide the starting point immediately preceding downcutting

geoarchaeological alluvial terrace system in tarazona chronostratigraphical transition of mode 2 to mode 3 during the middle upper pleistocene in the guadalquivir river valley seville spain abstract a geoarchaeological study of some lithic assemblages found in late middle pleistocene and beginning upper pleistocene alluvial terraces system has been carried out the mis 6 mis 5 transition in the fluvial terraces of the guadalquivir river has been identified in the middle terraces complex mtc at tarazona t11 1 44 38 m and t11 2 36 30 m seville spain the results were obtained from an archaeological excavation tar iii and two other complementary archaeological sites tar i and tar ii geomorphological cartography chronostratigraphic study with osl dating cantometric analysis and technotypological characterization of 5870 lithic pieces measurement techniques for erosion and transport on gravels and lithic have been accomplished the alluvial chronosequence shows a probable climatic character with autocyclic sedimentary processes correlated with the transition from mis 6 to mis 5 four alluvial episodes with associated lithic techno complexes were identified which refer to the chronostratigraphic transition from mode 2 to mode 3 during the late middle pleistocene mis 6 and the beginning of upper pleistocene mis 5 episode 1 with mode 2 mis 6 episode 2 with varied assemblages that could be associated to mode 2 or mode 3 129 121 ka mis 5e and mis 5d pre 110 ka episode 3 with mode 3 between 110 and 104 ka mis 5c and episode 4 with mode 3 post mis 5c the archaeological sites have lithic pieces which were knapped in situ workshop habitual or temporary sites or were slightly displaced the raw material selection of high quality quartzites from alluvial deposits is very notable during mode 2 acheulian tar i2 mode 2 or mode 3 assemblages tar iii5 and mode 3 tar iii1 2 3 during mode 3 middle paleolithic tar ii1 the selection of flint raw material was from areas near or in the guadalquivir terraces

river terraces as a response to climatic forcing formation processes sedimentary characteristics and sites for human occupation abstract climate impact on the fluvial processes led to morphological and sedimentological differentiation of a terrace this diversity in the fluvial environment determined how people could adapt to the river although the climatic impact on development and initiation of river terraces seems to be well accepted a number of pertinent questions disturb this simplicity for instance the exact terrace development within a climate cycle is still under debate different kinds of terraces and their sedimentary successions may originate either from aggradation incision or lateral migration is there a typical sedimentary succession below terraces what is the genetic origin of each sedimentary layer what are the relative ages of those layers and erosion phases within a climate driven erosion aggradation cycle the variability in staircase preservation in relation to climatic cyclicity is analysed in three scenarios specific scenarios depend essentially on the preservation of the fluvial deposits dating from the warm periods finally a preliminary inventory is presented of the most favourable sites for human occupation in fluvial valleys as derived from a random selection of archaeological findings generally human occupation in that morphological position seems to be linked with at least temporarily dry conditions climatic conditions do not seem to play the major role the termination of a settlement may have been due to increased risks of flooding apart from other than natural fluvio environmental reasons

climatic reconstruction of the weichselian pleniglacial in northwestern and central europe a multiproxy approach is applied to reconstructing accurately the weichselian pleniglacial climate 72 13 ka in northwestern and central europe standardised translations are used to transform proxy data into climate parameter values for six characteristic time windows quantitative reconstructions of the temperature regime are derived from periglacial coleoptera and botanical evidence while aeolian and fluvial evidence provide qualitative information on wind activity and precipitation respectively the early pleniglacial 74 59 ka the cold period between 41 38 ka and the late pleniglacial 27 13 ka are characterised by a strong north to south climatic gradient over northwestern europe during the last glacial maximum discontinuous permafrost was established in northern france whereas the continuous permafrost zone extended from the uk belgium the netherlands germany and poland to the nordic ice sheets prominent wind activity and a relatively low precipitation typify these periods in contrast an indistinct west to east climate gradient was present in the relatively more temperate intervals e g 50 41 ka seasonally frozen ground conditions prevailed in northwestern europe whereas discontinuous permafrost may be suggested for central germany it appears that the climate conditions in northwest and central europe were controlled by three major factors the scandinavian ice sheet the north atlantic surface water circulation and the russian continent 1998 john wiley sons ltd

limits of downstream hydraulic geometry adjustments to flow width depth and velocity in response to changes in discharge are commonly characterized by using downstream hydraulic geometry relationships the spatial limits of these relationships within a drainage basin have not been systematically quantified where the erosional resistance of the channel substrate is sufficiently large hydraulic driving forces presumably will be unable to adjust channel form data sets from 10 mountain rivers in the united states panama nepal and new zealand are used in this study to explore the limits of downstream hydraulic geometry relationships where the ratio of stream power to sediment size d 84 exceeds 10 000 kg s3 downstream hydraulic geometry is well developed where the ratio falls below 10 000 kg s3 downstream hydraulic geometry relationships are poorly developed these limitations on downstream hydraulic geometry have important implications for channel engineering and simulations of landscape change

factors determining subsidence in urbanized floodplains evidence from mt insar in seville southern spain major rivers have traditionally been linked with important human settlements throughout history the growth of cities over recent river deposits makes necessary the use of multidisciplinary approaches to characterize the evolution of drainage networks in urbanized areas since under consolidated fluvial sediments are especially sensitive to compaction their spatial distribution thickness and mechanical behavior must be studied here we report on subsidence in the city of seville southern spain between 2003 and 2010 through the analysis of the results obtained with the multi temporal insar mt insar technique in addition the temporal evolution of the subsidence is correlated with the rainfall the river water column and the piezometric level finally we characterize the geotechnical parameters of the fluvial sediments and calculate the theoretical settlement in the most representative sectors deformation maps clearly indicate that the spatial extent of subsidence is controlled by the distribution of under consolidated fine grained fluvial sediments at heights comprised in the range of river level variation this is clearly evident at the western margin of the river and the surroundings of its tributaries and differs from rainfall results as consequence of the anthropic regulation of the river on the other hand this influence is not detected at the eastern margin due to the shallow presence of coarse grain consolidated sediments of different terrace levels the derived results prove valuable for implementing urban planning strategies and the insar technique can therefore be considered as a complementary tool to help unravel the subsidence tendency of cities located over under consolidated fluvial deposits

paleomorphological and botanical evolution of small lowland valleys a case study of the mark valley in northern belgium abstract the sequence of fluvial activity in the lowland rivers is investigated by the case study of the mark valley at least five erosion sedimentation cycles from the middle pleistocene up to now are recognized in a detailed geological cross section made by handborings the organic accumulations of the holocene floodplain and a deep late glacial incision are pollenanalytically investigated they allow the reconstruction of the vegetational history and paleoecological evolution of the mark valley from the alerod to the atlantic the valley form and sedimentary environment at each cycle explain the morphology of the valley

constraints on the depth and variability of the lunar regolith knowledge of regolith depth structure is important for a variety of studies of the moon and other bodies such as mercury and asteroids lunar regolith depths have been estimated using morphological techniques i e quaide and oberbeck 1968 shoemaker and morris 1969 crater counting techniques shoemaker et al 1969 and seismic studies i e watkins and kovach 1973 cooper et al 1974 these diverse methods provide good first order estimates of regolith depths across large distances tens to hundreds of kilometers but may not clearly elucidate the variability of regolith depth locally 100 m to km scale in order to better constrain the regional average depth and local variability of the regolith we investigate several techniques first we find that the apparent equilibrium diameter of a crater population increases with an increasing solar incidence angle and this affects the inferred regolith depth by increasing the range of predicted depths from 7 15 m depth at 100 m equilibrium diameter to 8 40 m at 300 m equilibrium diameter second we examine the frequency and distribution of blocky craters in selected lunar mare areas and find a range of regolith depths 8 31 m that compares favorably with results from the equilibrium diameter method 8 33 m for areas of similar age 2 5 billion years finally we examine the utility of using clementine optical maturity parameter images lucey et al 2000 to determine regolith depth the resolution of clementine images 100 m pixel prohibits determination of absolute depths but this method has the potential to give relative depths and if higher resolution spectral data were available could yield absolute depths

statistical analysis of lateral migration of the rio grande new mexico abstract the lateral migration rates of alluvial rivers are affected by changes in water and sediment regimes the rio grande downstream from cochiti dam exhibits spatial and temporal variability in lateral movement rates documented since 1918 a tremendous database exists that documents planform bed material size channel geometry and water and sediment regimes a statistical analysis reveals that migration rates primarily decreased with decreasing flow energy r2 0 50 p 60 the findings show that lateral movement increases with increasing flow energy and with degree of braiding

the influence of bank strength on channel geometry an integrated analysis of some observations bank strength exerts a significant influence on river channel geometry but quantification of this relationship has been limited to only a few specific circumstances this is due to both the complex nature of bank strength and the difficulty in incorporating its influence in river channel geometry relations in order to undertake an integrated analysis of wide ranging field observations this study applies a recently developed multivariate model of channel geometry when the banks of a number of laterally stable streams are categorized on the basis of the bank sediment and vegetation the multivariate model yields numerical indices of bank strength within the range of the data analysed bank strength can produce a three fold change in channel width and a two fold change in depth corresponding to about a 1 6 fold change in cross sectional area 1998 john wiley sons ltd

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

the reconstruction of past climates using multi proxy evidence an example of the weichselian pleniglacial in northwest and central europe abstract different lines of terrestrial biotic and abiotic evidence are used for large scale climate reconstructions to transform proxy data into climate parameter values standardisation procedures are defined and described as each type of biotic and abiotic proxy provides its own climate parameter a detailed climate reconstruction may be obtained the multi proxy database for palaeoclimate reconstruction is a specially designed computer database that facilitates data processing and management of weichselian climate proxies this paper describes the application of multi proxy evidence to reconstruct the climate across lowland northwest and central europe during the interval 41 38 bp for this period the mean temperature of the warmest month is estimated at 10 to 11 c and the mean temperature of the coldest month ranges from 27 to 20 c the annual range suggests a cold continental setting with an estimated mean annual temperature between 9 and 4 c a north to south transition from dis continuous permafrost to seasonally frozen ground is suggested by periglacial evidence

stable channels with mobile gravel beds regime type equations for mobile gravel bed rivers are presented based on data obtained from 62 stable gravel bed river reaches in the united kingdom multiple regression techniques are applied to derive equations relating reach average and riffle values of width mean and maximum depth slope velocity sinuosity and riffle spacing to bankfull discharge bed and bank material characteristics valley slope bank vegetation type and an independent estimate of bankfull bed load transport rates although discharge has a dominant control on channel geometry these equations indicate that bed load discharge also has a significant influence particularly with regard to channel slope bank vegetation has a major control on width and velocity while depth velocity and slope are storngly affected by bed material size reasons for these results are considered in terms of the physical processes controlling channel adjustment the application of these regime equations is discussed and particular consideration is given to the design of sinuous channels with a pool riffle bed topograph

predicting gully width and widening rates from upstream contribution area and rainfall a case study in sw spain abstract gully width w is usually characterized by having a power relation with discharge however calculating runoff discharge in ungauged basins where these gullies typically form is inherently difficult and associated with large uncertainties this paper examines a simplified approach to relating gully width directly to the runoff contributing area a in a cultivated area in sw spain the effect of rainfall and land use on this w a relation was also analysed gully width was measured in 46 sections through the analysis of 10 historical orthophotos between 1956 and 2013 in a 21 km2 catchment in s spain these were validated by field measurements in 2013 widening rates varied strongly over time at between 0 and 2 19 m year 1 no significant differences in the gully widening rates were found between the two land uses present in the study zone olive groves and herbaceous crops the data obtained show a significant power relation of the form w a for all time periods analysed except for 1980 when many gullies were filled in artificially due to a change in land use in the study area the power relation coefficient varied at between 0 2 and 0 3 a good correlation was obtained between the number of days with daily rainfall of above 13 mm and the increase in the coefficient over time the results of this study on gully width dynamics provide new insights into improving the estimation of gully volume for example in combination with gully headcut retreat models and including the effects of different climate scenarios

sensitivity of weichselian fluvial systems to climate change nochten mine eastern germany abstract this paper aims to contribute to the understanding of fluvial system response to climate change during the last glacial interglacial cycle fluvial and aeolian successions have been studied in the opencast brown coal mine nochten in eastern germany an absolute chronology was established by luminescence and 14 c dating enabling to demonstrate the relations between depositional units and changes in sedimentary environment over time with regional climatic and vegetational changes it is concluded that the major climatic periods coinciding with the oxygen isotope stages are generally reflected in the fluvial sequence by distinct fluvial environments major climatic changes oxygen isotope stage boundaries have been preserved in the fluvial record as erosional bounding surfaces and by changes in fluvial style rapid climate changes like the middle pleniglacial dansgaard oeschger cycles are in general not reflected in the fluvial succession these cycles were too short or with too low amplitude to cause a strong vegetational response and related changes in water and sediment supply it is emphasized that also the preservation potential of short lived climatic warming events in high energy fluvial systems is low warming events may however have been preserved in lacustrine successions in former thermokarst lakes a strong cooling event at ca 40 ka leading to continuous permafrost conditions and changes in the water and sediment budget was reflected in the fluvial archive by a change from sandy anabranching to braided river conditions

stability analysis of semicohesive streambanks with concepts coupling field and laboratory investigations to quantify the onset of fluvial erosion and mass failure abstractthe overarching goal of this study is to perform a comprehensive bank stability analysis that is phenomenologically sound by considering both mass failure and fluvial erosion the nature of this study is twofold first field and experimental analyses are conducted to generate data for channel cross section properties soil index properties and mechanical and erosional strengths at two sites in a representative midsize midwestern stream in southeastern iowa that is subjected to frequent flash floods and characterized by active fluvial erosion and cantilever failure second the channel surveys and data obtained from the field and laboratory analyses are used as input parameters for an established one dimensional channel evolution model namely the conservational channel evolution and pollutant transport system concepts version 2 0 langendoen and alonso 2008 to estimate the factor of safety for mass failure fsm and fluvial erosion fsf and simulate the bank retreat as a result of eithe

channel changes in the jarama and tagus rivers central spain over the past 500 years abstract long term channel changes of the tagus and the jarama rivers in central spain were studied in relation to variations in hydroclimatic factors such as rainfall and flooding and also with respect to human activities undertaken in their valleys data were taken from historical 1580 1823 and topographical 1877 1988 maps as well as aerial photographs 1945 1999 the available hydroclimatic data consists of a series of monthly rainfall totals 1859 1994 and mean river flow values recorded at gauging stations 1911 1985 in addition a historical flood record 1550 1947 was produced from documentary sources some of the data was incorporated into a geographical information system gis to quantify the changes in the course of the rivers the results show there have been two distinct periods before and after human intervention in the river system which took place around 1950 during the earlier period 1550 1950 a correlation exists between climate frequency and magnitude of flooding and changes in fluvial geomorphology between 1860 and 1892 an increase in flood frequency and magnitude occurred which produced half of the cut offs recorded in the study area between 1823 and 1877 the meanders length l width w and radius of curvature rc of the tagus river have decreased since 1750 however those of the jarama reached their maximum values during flood periods both rivers have different geomorphological responses during flood events which can explain these different trends floods in the jarama not only led to the cut offs but also enlarged the channel size l w and rc in the second period 1956 present flow regulation via dams and gravel mining modified the system completely and impeded the natural development of these rivers

lead isotope signatures of holocene fluvial sediments from the loire river valley abstract the distribution of mn v th pb and isotopes of pb in the labile fraction of sediments from a channel infill in the middle loire alluvial plain are used to highlight some aspects of the basin evolution over the period from 0 to 10 ka bp the acid extractable matter aem in the sediment samples is variable in amount and in trace element contents iron mn oxyhydroxides are the principle trace element carrying phase in the labile fraction and carbonates are a secondary carrier vanadium and pb originate from the weathering of silicates and are used as a silicate erosion rate index in the fluviatile record most of the aem data plot along a general trend between 3 endmembers basalts cretaceous carbonate rocks and granites in the relationship between 207pb 206pb and 206pb 206pb these endmembers have been mixed in various proportions depending on natural holocene inputs erosion volcanic events or human influences mining and smelting of ore

holocene floodplain metamorphosis in the midlands united kingdom abstract many lowland rivers in the united kingdom including the nene soar and severn have layered floodplains with a basal gravel of pleistocene or late glacial age and a structureless silty clay superficial unit burying the entire former floodplain this burial is illustrated by the existence of variable mixed and pedologically disturbed sediments and palaeo landsurfaces between the basal gravels and superficial silty clay this paper presents a comparison of the pre and post late holocene palaeo landsurfaces and palaeochannels using data from the nene soar and severn valleys from this comparison it is argued that during the mid to late holocene ca 4500 yr bp to 2500 yr bp floodplains and river channels underwent a metamorphosis this is indicated by accelerated vertical accretion a reduction in floodplain relative relief changed floodplain soil conditions a reduction in channel w d ratios and a resultant increase in the silty clay proportion of channel perimeter sediments there are indications that hydrological change preceded this metamorphosis but the primary cause was an increase in fine sediment supply during the later holocene and a disequilibrium between channel bed and floodplain aggradation rates resulting in relative incision this metamorphosis which is explained in this paper by the proposed stable bed aggrading banks model sbab is the key factor in the holocene evolution of low energy floodplain systems in the united kingdom upon which more subtle short term fluctuations are superimposed

late quaternary climatic change in france estimated from multivariate pollen time series abstract in regions like southern france where usual analytical techniques are unsatisfactory due to the heavy influence of human activity and the existence of a complex climate the quantitative reconstruction of climate from pollen is particularly difficult that is why an original method has been performed the first step of the method based on best analogs estimation and multiple regression is to calculate a relationship between climate monthly temperature and precipitation and modern pollen spectra for data from 182 sites the result is called the analog climate the second step of the method an original combination of canonical correlation and principal components analyses extracts the common information from several fossil pollen sequences to produce a so called paleobioclimate this step removes the effects of local differences in the vegetation among nearby sites and also reduces the effects of human disturbance in the third step the signals obtained from the first two steps are merged by kalman filter into a final reconstruction where the noise is reduced by around 37 the results presented with a 95 confidence level suggest that the pleni wurm was 7 to 13 c colder than present and had 20 to 60 less precipitation than today this large confidence takes into account the climatic diversity of the region at 13 000 yr b p the climate reached the modern level of precipitation but the temperature was just less than present the subsequent decrease of precipitation is less important than that of temperature this fact may explain the advance of alpine glaciers during the younger dryas preboreal warming was abrupt 3 to 4 c per 500 yr and precipitation increased more slowly

quantitative analysis of climate versus human impact on sediment yield since the lateglacial the sarlieve palaeolake catchment france minimum rates of solid ssy and dissolved dsy sediment yield sy were evaluated in t km2 per yr from sediments stored in the sarlieve palaeolake french massif central for seven phases of the lateglacial and holocene up to the seventeenth century the catchment 29 km2 mainly formed of limestones and marls is located in an area rich in archaeological sites in the massif central the respective impacts of human activities and climate on sy were compared by quantification of human settlements through archaeological survey and palynological data during the lateglacial and early holocene up to about 7500 yr cal bp variations in ssy and dsy rates were mainly related to climate change with higher rates during colder periods younger dryas and preboreal and lower rates during warmer periods bolling allerod and boreal however cf1 tephra fallout induced a sharp increase in sy during the allerod during the middle and late holocene after 7500 yr cal bp ssy and dsy greatly increased by factors of 6 5 and 2 8 respectively particularly during the final neolithic at about 5300 yr cal bp when the climate became cooler and more humid after this date at least 75 of the ssy increase and more than 90 of the dsy increase resulted from human activities but ssy rates showed little variation during protohistoric and historic times up to the seventeenth century ssy and dsy rates and dsy ssy ratio indicate that catchment soils began to form during the lateglacial and preboreal thickened considerably during the boreal and atlantic finally thinning rejuvenation mainly as the result of human induced erosion during the sub boreal and sub atlantic increased mechanical erosion during the late holocene also induced an increase in chemical erosion

urban geo archaeology in medieval alzira prov valencia spain abstract alzira is situated in a cut off meander loop of the rio jucar geo archaeological study shows that the islamic city wall was built during the second quarter of the 11th century ad at a time when the river had a low amplitude and low energy flood regime after mid century overbank silts began to invade the city as peak flood discharge increased with a spate of destructive floods reflected by high energy deposits during the late 11th century urban expansion within the city wall is dated to the later 11th or early 12th century interrupted by local abandonment and moderate energy flood silts major construction during the mid 12th century was followed by protracted abandonment after a siege in ad 1171 and further moderate energy flood silts that redistributed occupation and collapse debris reoccupation during the late 14th century was terminated by catastrophic floods in 1517 and 1571 after which much of the western end of alzira was not rebuilt following further flood catastrophes during the 17th century parts of the central walled city remained abandoned until the 19th century with new occupation atop flood sands of yet another disaster in 1864 the change in flood regime after 1150 was a result of deforestation of the watershed but progradation of a downstream tributary fan after 1517 created an unstable aggrading floodplain increasingly prone to severe flooding climatic anomalies were responsible for periods of recurrent severe floods archaeologically verified during the 11th and 12th centuries and historically documented beginning in 1318 the geo archaeological methodology illuminates the constructional and settlement history of alzira allows distinction of fluvial and cultural components and provides the necessary microstratigraphic detail and dating control to document the true complexity of alluvial processes during the last 1000 years

consistency of scaling relations among bedrock and alluvial channels 1 this paper presents field data on channel geometry and potential control variables from 47 field settings representing a diverse range of environments these data are used to evaluate existing scaling relationships used in models of the evolution of bedrock channel geometry and to test the hypothesis that channel width w increases more slowly and depth d more rapidly in relation to discharge q or drainage area a as substrate resistance increases for this data set w a0 3 w q0 5 d a0 2 and d q0 3 the w a and w q relations are close to those found by previous investigators the d a and d q relations have not previously been reported for bedrock channels examination of trends within the data does not support the hypothesis and instead suggests that the erosional resistance of channel boundaries is not the primary control on scaling relations for channel geometry

use of local soil and vegetation classifications to improve regional downstream hydraulic geometry relations abstractregional downstream hydraulic geometry equations are developed using flow with a 1 5 year recurrence interval and corresponding widths depths and velocities the study includes 634 gauge stations located across canada and are grouped by characteristics that affect or are correlated with bank and bed stability jack knife analysis was done to test the predictive capabilities of each grouping for width prediction grouping the data by geology and vegetative characteristics improved predictions in 14 of the 15 categories with drainage characteristics and mode of deposition groupings showing the best results grouping the data by vegetative characteristics showed the best improvement among noncontiguous categories when considering all of the hydraulic geometry variables width depth and velocity these groupings are investigated further the study demonstrates that classifying downstream hydraulic geometry equations by local geology and vegetation improves the predictive capabilities of the eq

river system evolution and environmental changes during the lateglacial in the paris basin france abstract lateglacial sequences from the paris basin floodplains provide a general overview of the valley s evolution related to climatic changes from the weichselian upper pleniglacial to the beginning of the holocene comparison between morphostratigraphical and palaeobiological data allows discussion of fluvial dynamics and related palaeoenvironmental conditions the upper pleniglacial oldest dryas transition remains poorly documented it is represented by sands and silts deposited by a braided channel network the bolling begins with a significant incision related to a meandering system which is followed by local organic and minerogenic deposition contemporaneous with vegetation development the older dryas is evident in several sequences the allerod appears more stable and the forest extension is accompanied by a thin soil formation on the banks the younger dryas is characterised by a strong infilling of the valleys by calcareous silts this last sharp event precedes a second major downcutting phase which takes place in the early postglacial and is followed by a decline in river flow and sediment supply this evolution reflects a broad regional pattern of fluvial response which illustrates its sensitivity to climatic change the study of various morphosedimentary contexts shows their influence on the fluvio dynamic record and bio proxies which complicates the detection of minor phases

downstream variations in the width of bedrock channels field surveys of channel width w and drainage area a in bedrock channel reaches reveal relationships where w 5 ca b similar to the classic hydraulic geometry of alluvial channels data from five mountain channel networks support the assumption used in many landscape evolution models that an alluvial hydraulic geometry relationship where b 5 0 3 0 5 holds for bedrock channel systems although there is substantial local variability in channel width in bedrock channel systems there is no systematic difference in width versus drainage area relations for the surveyed bedrock and alluvial reaches in sedimentary lithologies in coastal oregon and washington in contrast bedrock channels were narrower and therefore had deeper flow than alluvial channels with equal drainage areas in the granite and limestone terrain of the yuba river california in addition data from the mokelumne river show that bedrock channel width decreases substantially downstream at the contact between relatively weak limestone and more erosion resistant granite but that channel slope does not change appreciably across contacts between these two lithologies data from coastal oregon drainage basins further show systematic channel widening after flood flows and debris flow impacts we conclude that downstream variations in the width of bedrock channels generally follow traditional hydraulic geometry relations but also reflect the local influence of longitudinal patterns of bedrock erosivity and disturbance history

fluvial response to weichselian climate changes in the niederlausitz germany the last glacial shows large variations in climate which are reflected in the fluvial record in the niederlausitz eastern germany the entire sequence resembles the fluvial development in other river basins in northwestern europe which show contemporaneous changes in depositional style at the onset of a climatic change during the middle and the late pleniglacial permafrost conditions resulted in an episodic river discharge the presence or absence of vegetation in combination with such ephemeral stream conditions determined the type of river during each period a relatively well developed vegetation cover on the flood plains during the middle pleniglacial resulted in a low sediment yield in combination with the intermittent discharge this caused the development of an ephemeral anastomosing river system a river with stable channels and extensive sandy overbank areas the decline in vegetation cover at ca 28 ka bp caused an increase in sediment yield and peak discharges which resulted in the development of a sandy braided river in adjustment to these new conditions following the coldest period at around 20 ka precipitation was so low that fluvial activity was limited and aeolian deposition took place in the valley 1997 by john wiley sons ltd

crossing forest thresholds inertia and collapse in a holocene sequence from south central spain a holocene palaeoecological sequence from villaverde south central spain is presented the pollen stratigraphy is used to infer past vegetation changes within a catchment area that represents the boundary between semi arid plateau and mountain vegetation from c 9700 7530 cal yr bp pinus is dominant probably as a result of a combination of a relatively dry climate and natural fire disturbance from c 7530 5900 cal yr bp moderate invasion by quercus appears to be a migrational response following increased moisture and temperature but in part shaped by competitive adjustments from c 5900 5000 cal yr bp the pine forests are replaced by deciduous quercus forests with an important contribution from corylus betula fraxinus and alnus mediterranean type forests spread from c 5000 to 1920 cal yr bp coincident with expansions of artemisia juniperus and other xerophytes from c 1920 1160 cal yr bp pinus becomes dominant after a disturbance mediated invasion of the oak forests human impact u

downstream hydraulic geometry of clay dominated cohesive bed rivers empirical downstream hydraulic geometry equations for consolidated clay dominated cohesive bed nonalluvial natural streams are presented using data from six rivers in eastern ontario canada and four rivers from other regions the width exponent 0 57 was comparable to the exponents reported for previous studies however the depth exponent 0 52 was greater for clay dominated cohesive bed than for typical alluvial gravel bed and sand bed rivers the width to depth ratio of smaller channels qbf 20 m3 s was greater for consolidated clay bed than for either sand bed or gravel bed channels this study suggests that the concept of hydraulic geometry and bankfull channel forming discharge can be extended to nonalluvial consolidated clay bed channels