correlation of fluvial sequences in the mediterranean basin over the last 200 ka and their relationship to climate change macklin mark fuller i c lewin j maas g a 2002 correlation of fluvial sequences in the mediterranean basin over the last 200 ka and their relationship to climate change quaternary science reviews 21 14 15 pp 1633 1641 rae2008

some observations on suspended sediment dynamics in storbregrova jotunheimen observations are reported of the dynamics of suspended sediment transport in the meltstream of storbreen in the jotunheimen fine sediment is transferred from the subglacial to the proglacial environment during low flow meltdominated periods and then removed from the catchment during high flow rainfall controlled events both diurnal and storm period sediment load discharge relationships involve clockwise hysteresis but separate multivariate rating curves define variations of load with streamflow according to 1 the relative importance of meltwater and rainfall runoff and 2 changes in the sediment source areas contributing to the stream at different times particle size variations in the suspended sediment also reflect varying source area influences

tidal fluxes of nutrients and suspended sediments at the north inlet winyah bay national estuarine research reserve beginning june of 1993 suites of 13 water samples have been collected at oyster landing north inlet sc every 20 days covering two consecutive tidal cycles at 2 07 h intervals in order to ascertain whether this large and still growing water chemistry data set can be used to determine tidal fluxes of nutrients and sediments we coupled measured concentrations to estimates of instantaneous tidal discharge based on a basin water storage curve and hindcast tides the mean advective fluxes of all constituents including salt showed statistically significant exports this result however is largely due to an ebb bias in the sampling protocol which resulted in 52 of the samples being collected on ebb tide versus a theoretical percentage of 48 when this bias was corrected by reducing the mean discharge 610 l s 1 to a value 125 l s 1 that produced a balance between the mean advective and dispersive salt fluxes the advective fluxes of the other constituents were reduced to values that are not significantly different from zero in addition to a statistically significant dispersive influx of salt significant dispersive exports were found for don nh4 dop po4 and doc all particulate constituents pn pp iss and oss yielded dispersive fluxes that were not significantly different from zero annual material budgets for the oyster landing basin based on the dispersive fluxes of all constituents except salt are generally similar in magnitude and direction to those measured by dame r f spurrier j d williams t m kjerfve b zingmark r g wolaver t g chrzanowski t h mckeller h n vernberg f j 1991 annual material processing by a salt marsh estuarine basin in south carolina usa marine ecology progress series 72 153e166 in the nearby and ecologically similar bly creek basin indicating that the dispersive fluxes determined in this study are realistic we offer suggestions for improving the reliability and usefulness of future oyster landing water quality data 2006 elsevier ltd all rights reserved

erosion caused by hyperconcentrated flow on the loess plateau of china abstract hyperconcentrated flows are widely observed in the middle yellow river basin they occur as a result of erosion but once they form on slopes they operate as a strong eroding and sediment carrying force and play an important role in drainage basin erosion and sediment production processes since the energy expenditure is less and sediment carrying capacity is greater hyperconcentrated flows have very high eroding and transporting abilities there exists a strong coupling relation between hyperconcentrated flow transport and gravitational erosion which ensures a rapid removal of mass wasted materials hyperconcentrated flows are an important factor responsible for the high intensity erosion and sediment yield in the middle yellow river basin many previous studies have indicated that the sediment delivery ratio on the loess plateau approaches 1 this can be explained by the action of hyperconcentrated flows as hyperconcentrated flows exhibit some particular behaviors in erosion and sediment production processes the present study suggests that the erosion by hyperconcentrated flows be regarded as a special type of erosion accordingly some countermeasures are proposed to control hyperconcentrated flows and the resulting erosion

correlating check dam sedimentation and rainstorm characteristics on the loess plateau china on the loess plateau china check dams are necessary for soil and water conservation in this study the relationships between check dam sedimentation and storm characteristics were investigated and rainstorm events for an area of data scarcity were reconstructed using optimal regression models four typical check dams of the loess plateau the shipanmao hualiang no 3 guandigou and no 4 guandigou dams were selected for case studies soil profiles behind the four dams were divided into 21 25 31 and 31 layers respectively the one toone link between sediment layers and corresponding storm characteristics were considered based on the peak fallout of 137cs and on the principle that higher flow corresponds to higher sediment deposition volume analysis showed that the layered sediment volume v was closely related to rainfall erosivity r and to the maximum rainfall intensity over 30 min 130 a statistically significant power regression model between v and r was observed along with an exponential regression model between vand i 30 based on the power regression model between v and r a new approach was developed in order to reconstruct rainfall erosivity in rainfall data scarcity areas different hysteresis patterns counterclockwise clockwise and hybrid at the single storm scale were observed between v and r for the shipanmao dam deposition wedge depositional area behind a dam and these impacted differently on the scale reconstruction results however the distance between the reconstructed dams and the known dams had an even stronger influence the scale method developed in this study was shown to perform well and was able to reconstruct rainstorm events for adjacent regions with similar climatic and geomorphological conditions furthermore the results of this study have improved our understanding of single rainstorm dynamics and soil erosion mechanisms on the loess plateau c 2016 elsevier b v all rights reserved

the sedimentary and geomorphological imprint of the ad 365 tsunami on the coasts of southwestern crete greece examples from sougia and palaiochora abstract the southwestern coast of crete one of the most seismically active regions in europe experienced co seismic crust uplift by 9 m during the ms 8 3 mega earthquake that struck the eastern mediterranean world on 21 july ad 365 an associated tsunami event caused thousands of fatalities and destroyed many coastal settlements and infrastructure between the levante in the east and the adriatic sea in the northwest so far coastal sedimentary archives in southwestern crete including distinct palaeotsunami fingerprints are rarely investigated therefore a multi proxy study including sedimentological geochemical geochronological and microfaunal methods was conducted in order to detect onshore coastal sedimentary archives that functioned as fine sediment traps and document palaeotsunami imprint we found adequate archives at the sougia and palaiochora coastal plains that were used to reconstruct the palaeogeographical evolution and the palaeoseismological history of sw crete during the late holocene our studies revealed distinct geomorphological sedimentological geochemical and microfaunal traces of high energy impact from the marine side related to seismic events at the sougia coastal plain a sheet of fine sand with a neat microfossil and geochemical fingerprint was found sandwiched between underlying pre tsunami muds and overlying post tsunami colluvial silt in the palaiochora coastal plain tsunami overflow of a flat neogene bedrock platform led to the accumulation of sand dominated deposits that were subsequently covered by colluvial material from the adjacent hillslopes based on radiocarbon and luminescence dating approaches it is shown that the ad 365 tsunami event is the best fit candidate for the tsunami related sediments deposited at both sougia and palaiochora this study for the first time presents multi proxy evidence of the ad 365 tsunami imprint on fine sedimentary archives along the western and southwestern coast of crete

intra event and inter seasonal behaviour of suspended sediment in flash floods of the semi arid northern negev israel abstract a better understanding of the relation between suspended sediment concentration and water discharge is gained by recognizing amongst other things the different impacts of two types of rainfall event wandering discrete convective or convectively enhanced high intensity storms and ubiquitous multi celled low intensity frontal storms in the levant the first type is characteristic of autumn and spring and the flushing of sediment by the instant onset of high intensity rainfall produces a clockwise hysteresis in the suspended sediment water discharge relation the second type is characteristic of winter and can be marked by either anticlockwise or no hysteresis in the suspended sediment water discharge relation sedimentary flushing is rarely apparent suspended sediment concentrations in flash floods resulting from convective storms are high typically 10 4 10 5 mg l 1 but correlation with water discharge is low r 0 57 in contrast frontal storm runoff carries lower suspended sediment concentrations typically 10 3 10 4 mg l 1 and correlation with water discharge is better r 0 78 this division assists in interpreting the high degree of scatter evident in the overall suspended sediment concentration water discharge relation but it reveals that much is yet to be learned about the interplay of the disposition of cellular storm tracks and sediment source areas

the value of lichenometry and historical archives in assessing the incision of submediterranean rivers from the little ice age in the ardeche and upper loire france the geomorphologic impact of the little ice age lia was determined on two french mediterranean rivers the upper ardeche and the upper loire in order to evaluate the impact of the lia on the hydrology of these rivers two historical flood chronicles were made from historical sources the lia can be divided in three phases of high activity 1530 1700 1750 1810 1840 1910 a geomorphologic study of the two rivers shows that incision is the principle process at work in the 20th century in order to date the low terraces and bedforms present in both valleys lichenometry was used rhizocarpon geographicum allowed the main features on the bottom of the valley to be dated using two growth curves made for the two studied areas in the ardeche lichenometric dating showed a progressive evacuation of the inherited alluvial stock the oldest lichens found on the foodplain and the outcrops indicate that incision began between the second half of the 17th century and the end of the 18th century in the mid little ice age incision stopped on the bedrock in the second half of the 19th century in the loire the narrowness of the gorge did not allow sediment to be stored during the first half of the lia very old lichens 1000 yr of age are present on the bedrock close to the bed however at a number of locations the valley slightly widens allowing sediment that was transiting through the gorge to be stored the geomorphologic features that characterise these basins clearly show a hydrosedimentary behaviour different before and after the beginning of the 20th century

first evidence of a lake at ancient phaistos messara plain south central crete greece reconstructing paleoenvironments and differentiating the roles of human land use and paleoclimate from minoan to roman times phaistos was one of the most important minoan palaces in crete and previous studies have addressed its relationship with the paleo seashore position during historical times here we reconstruct the environmental evolution of phaistos from early minoan to roman times study of two stratigraphic sections and nine boreholes drilled in the westernmost part of the messara plain has revealed the stratigraphy of the mid to late holocene sediments laboratory analyses comprise granulometry magnetic susceptibility measurements and identification of mollusks diatoms and pollen grains eighteen radiocarbon dates provide a robust chronostratigraphy in addition a geophysical survey electric resistivity tomography ert method was conducted to reveal the sub surface morphology in the coring area the results reveal that a freshwater lake existed from ca 2100 2000 bc to ca 1200 1100 bc which subsequently became swampland until ca 700 bc a lake retreat is identified at ca 1200 1000 bc and can be interpreted as resulting from the 3 2 cal kyr bp rapid climate change rcc dry event observed elsewhere in the eastern mediterranean subsequently from the 7th to the 5th century bc there was the input of detrital material and fluvial dynamics prevailed until at least roman times the origin of the lake and its disappearance are discussed in the context of regional climate change and local tectonic activity without excluding possible human influences we also reconstruct the vegetation history for the period from the late minoan to the early archaic period pollen analysis reveals a mediterranean maquis landscape dominated by olea together with hygrophilous vegetation and highlights a clear transition from limnic to swampy environmental conditions around 1100 bc the pollen sequence is also important for assessing the impact of the 3 2 cal kyr bp rcc event and for assessing the possibility of an abrupt discontinuity in human activity around phaistos after the demise of the minoan civilization

human impacts on fluvial systems in the mediterranean region the long history of substantial human impacts on the landscape of the mediterranean region and their effects on fluvial systems is documented these effects have included impacts of deforestation and other land use changes agricultural terracing on a wide scale water transfers and irrigation schemes during the 20th century major changes were made directly to channels through channelisation construction of dams of various sizes and extraction of gravel and indirectly by reforestation these changes have caused a major phase of incision on some rivers runoff and soil erosion have been affected by types of crops and agricultural practices as well as by the varying extent of cultivation and grazing some recent agricultural practices involve wholescale relandscaping of the topography and alteration of surface properties of material the importance of analysing the connectivity within different land units and of the spatial position of human activity within a catchment is illustrated the analysis of connectivity is the key to understanding the variability of impact and the extent of propagation of effects

growth rates of rhizocarpon geographicum lichens a review with new data from iceland this paper reviews evidence from previous growth rate studies on lichens of the yellow green species of subgenus rhizocarpon the family most commonly used in lichenometric dating new data are presented from rhizocarpon section rhizocarpon thalli growing on a moraine in southern iceland over a period of 4 33yr measurements of 38 lichen thalli between 2001 and 2005 show that diametral growth rate dgr mmyr 1 is a function of thallus size growth rates increase rapidly in small thalli 50 mm diameter mean dgr in southern iceland between 2001 and 2005 was 0 64 mm yr 1 sd 0 24 the resultant growth rate curve is parabolic and is best described by a third order polynomial function the striking similarity between these findings in iceland and those of armstrong 1983 in wales implies that the shape of the growth rate curve may be characteristic of rhizocarpon geographicum lichens the difference between the absolute growth rate in southern iceland and wales ca 66 faster is probably a function of climate and micro environment between the two sites these findings have implications for previous lichenometric dating studies namely that those studies which assume constant lichen growth rates over many decades are probably unreliable british geological survey natural environment research council copyright 2006

temporal distribution of suspended sediment transport in a mediterranean basin the lower tordera ne spain abstract suspended sediment dynamics are still imperfectly understood especially in areas of mediterranean climate with strong seasonal contrasts where few studies have been conducted the aim of this study is to analyze the variability in the suspended sediment load at different temporal scales within flood variability monthly seasonal and annual in the tordera river 894 km 2 located in northeastern spain suspended sediment samples were obtained during base flows q 3 5 m 3 s 1 and flood events q 3 5 m 3 s 1 the analysis of the variability in the suspended sediment is structured in two consecutive steps i the construction of statistical relations between suspended sediment concentrations c and discharge q and ii the application of those relations to assess the suspended sediment yield the results show that in a single event the sediment peak generally precedes the peak discharge following a clockwise hysteretic loop furthermore it was observed that the reduction in the suspended sediment concentrations in a sequence of events can be mainly associated with a phenomenon of sediment exhaustion the total amount of suspended sediment transported during a single flood is thus related to its duration and time during the year as well as to its magnitude at a seasonal scale the export of suspended sediment takes place in two phases i sediment preparation and ii sediment transfer and exhaustion during the latter phase the exhaustion of the sediment load is primarily related to the sequence of flood events at the annual scale the results show high inter annual variability according to the number of floods recorded yearly since almost all the suspended load is transported during those events

millennial scale climatic cycles in the early pliocene pollen record of ptolemais northern greece early pliocene lacustrine sediments from the ptolemais basin northern greece exhibit a climatically induced cyclicity which can be correlated with the orbital cycle of precession superimposed on precession controlled cycles palynological time series data reveal a higher order climatic cyclicity with periodicities of 10 2 5 and 1 5 ka these millennial scale vegetation changes are likely to reflect changes of the soil moisture gradient on mountain slopes caused by fluctuations in orographic winter precipitation such fluctuations corroborate the concept of a nao like north atlantic climatic teleconnection during early pliocene times the periodicities are similar to those of climate oscillations inferred from quaternary records the occurrence of millennial scale cyclicity in a time interval when the northern hemisphere was essentially ice free implies an ultimate forcing mechanism that operated independently of changes in the thermohaline circulation in the atlantic ocean the cycles are likely to be related to long period variations in solar activity

modelling the runoff sediment yield relationship using a proportional function in hilly areas of the loess plateau north china based on data observed at the 12 small watersheds in hilly areas of the loess plateau north china the relationship between event runoff volume and sediment yield is examined the results reveal that the runoff sediment yield relationship at the inter event timescale is mainly determined by the runoff sediment concentration relationship at the intra event timescale in the study area the sediment concentration tends to be stable when the flow discharge exceeds a certain critical value many factors that are important for determining the characteristics of low magnitude events such as flow discharge particle size of fluvial sediment and accumulation of loose material on land surfaces prior to a rainstorm appear to have little importance for high magnitude events consequently mean sediment concentration tends to be stable for large flood events suggesting a strong similarity between the two flow sediment relationships at inter and intra event temporal scales furthermore a proportional function is proposed to predict event sediment yield and the correspondence between the predicted and observed sediment yields is examined the performance of the model is good for high magnitude events especially extreme events the applicability of the proposed model at the annual timescale is also discussed

the effective elastic thickness of the continental lithosphere comparison between rheological and inverse approaches 1 following the release of global continental effective elastic thickness te maps obtained using different approaches we now have the opportunity to provide better constraints on te we improve previous estimates of te derived from thermo rheological models of lithospheric strength or ter using new equations that consider variations of the young s modulus in the lithosphere these new values are quantitatively compared with those obtained from an inverse approach or tei based on a comparison of the spectral coherence between topography and gravity anomalies with the flexural response of an equivalent elastic plate to loading the two models show in general a good agreement having equal means at the 95 significance level in about half of the continental areas in other regions tei exceeds ter in about 65 of the data points showing that tei provides an upper bound on te the two data sets have a similar range but demonstrate different distributions ter has a bimodal distribution with the two peaks representative of the cratons and of the areas outside of them in contrast tei has more uniform distribution without predominant peaks our models show higher similarities in the meso cenozoic orogens than in the archaean and proterozoic shields and platforms due to the methods employed for the regions with the most robust determinations of ter and tei the relationship between them is close to linear the results of this work can be used for further studies on the mechanical properties of the lithosphere

geomorphological records of extreme floods and their relationship to decadal scale climate change extreme rainfall and flood events in steep upland catchments leave geomorphological traces of their occurrence in the form of boulder berms debris cones and alluvial fans constraining the age of these features is critical to understanding i landscape evolution in response to past present and future climate changes and ii the magnitude frequency of extreme ungauged floods in small upland catchments this research focuses on the cambrian mountains of wales uk where lichenometric dating of geomorphological features and palaeohydrological reconstructions is combined with climatological data and documentary flood records our new data from wales highlight a distinct flood rich period between 1900 and 1960 similar to many other uk lichen dated records however this study sheds new light on the underlying climatic controls on upland flooding in small catchments although floods can occur in any season their timing is best explained by the summer north atlantic oscillation snao and shifts between negative wetter than average conditions with regular cyclonic flow and flooding and positive phases drier than average conditions with less frequent cyclonic flow and flooding which vary from individual summers to decadal and multidecadal periods recent wet summer weather flooding and boulder berm deposition in the uk 2007 2012 are related to a pronounced negative phase shift of the snao there is also increasing evidence that recent summer weather extremes in the mid latitudes may be related to arctic amplification and rapid sea ice loss if this is the case continuing and future climate change is likely to mean that i unusual weather patterns become more frequent and ii upland uk catchments will experience heightened flood risk and significant geomorphological changes

contrasts between debris flows hyperconcentrated flows and stream flows at a channel of mount semeru east java indonesia abstract in order to differentiate between different types of sediment laden flows in volcanic channels we carried out observation of debris flows hyperconcentrated flows and stream flows in the curah lengkong river on the southeast slope of mount semeru in east java indonesia the aims of this study are 1 to provide quantitative data for these flows in motion 2 to compare the data for different types of flow that occur in the same river 3 to assess the influence of rainfall on debris flows hyperconcentrated flows and streamflow generation the curah lengkong river transports large volumes of sediment in the range of 1 10 5 to 5 10 5 m 3 per debris flow and 10 3 to 10 5 m 3 per hyperconcentrated flow and stream flow large sediment discharges result from the following factors continuous and voluminous sediment supply of fine juvenile material by daily explosions of the semeru volcano pyroclastic source material emplaced on steep slopes strong erosion of weathered river banks and strong rainfall intensities the occurrence of the flows focuses in the period from november through april and the daily timing of it is the mid to late afternoon nearly all debris flows are triggered by stationary rainfall confined to the upper slopes of mount semeru whereas hyperconcentrated flows and stream flows are mainly generated by migratory or regional rains driven upwards on the eastern slope this slope receives its maximum of annual rainfall 3800 mm at 800 m asl the peak surface velocity of debris flows is always greater than the peak frontal velocity the peak discharge of debris flows occurs several minutes after the passage of the flow front volumetric concentrations of sediment are high 48 to 69 between the debris flow front and the point of peak discharge after the peak discharge it usually decreases gradually contrary to the case of debris flows high concentration of sediment appears in various portion of hyperconcentrated flows and stream flows near the front in the mid point or at the back of flows although the concentration of sediments in them is much less than in of debris flows relationships between sediment discharge total volume and peak discharge show a very strong positive correlation for debris flows and hyperconcentrated flows therefore sediment discharge can be roughly estimated from direct visual observation

paleoflood hydrology origin progress prospects from an origin in diverse studies of flood geomorphology and quaternary geology paleoflood hydrology emerged as a geophysical and an applied hydrological science during the 1970s and 1980s since acquiring its formal name in 1982 the most productive approach in paleoflood hydrology has become energy based inverse hydraulic modeling of discrete paleoflood events recorded in appropriate settings as slackwater deposits and other paleostage indicators swd psi or as various threshold indicators of non exceedence technological advances particularly in hydraulic modeling and geochronology were instrumental in moving the discipline to its present status the most recent advances include 1 new techniques for the accurate geochronology of flood sediments notably tams radiocarbon analyses and osl dating and 2 the phenomenal increase in computer power that allows complex hydraulic calculations to become feasible for routine studies from its initial demonstration in the southwestern united states swd psi paleoflood hydrology proved its widespread applicability to various landscape environments particularly important studies have been accomplished in australia china india israel south africa spain and thailand paleoflood hydrology has also generated its share of controversy in part because of the differing viewpoints and attitudes of the two scientific traditions from which it emerged quaternary geology geomorphology versus applied hydrologic hydraulic engineering nevertheless the future growth of the discipline is assured given the rapid pace of discoveries that it engenders indeed so many international studies exist that it is appropriate to pursue global syntheses to address interesting and timely questions of extreme flood phenomena in relation to global climatic change

the impact of recent climate change on flooding and sediment supply within a mediterranean mountain catchment southwestern crete greece maas g s macklin m g 2002 the impact of recent climate change on flooding and sediment supply within a mediterranean mountain catchment southwestern crete greece earth surface processes and landforms 27 10 1087 1105

event sequence and sediment exhaustion in the lower panuco basin mexico abstract although large tropical river systems transport the majority of the world s runoff and sediment few studies have examined the dynamics of suspended sediment transport in this setting this includes mexico which contains two of the larger river basins draining into the gulf of mexico this study provides a detailed analysis of discharge q and suspended sediment transport dynamics for the lower panuco basin 98 227 km2 of eastern mexico including the lower moctezuma lower tamuin and panuco rivers daily values of discharge and suspended sediment concentration ssc are examined for three stations spanning from the late 1950s to early 1990s although the panuco is a large basin the relationship between discharge and suspended sediment concentration represents a departure from the oft reported study by heidel trans am geophys union 37 1956 56 instead of sediment lagging discharge the sediment wave precedes discharge by an average of 1 7 days displaying pronounced clockwise positive hysteresis this may be due to the sources of runoff and sediment which are derived primarily in the lower reaches of the basin because of precipitation patterns geology and basin morphometry the distinct differences in lithology between the tamuin and moctezuma basins which join in the coastal plain to form the rio panuco allow the influence of geologic setting to be considered q ssc relations display positive hysteresis where the sediment is derived from erodible tertiary shale deposits in the moctezuma basin in contrast q ssc relations in the rio tamuin which transports less suspended sediment because of its karstic setting are more linear due to these relations being dependent on the entrainment of bed material consideration of the sequence of events during the rainy season suggests that much of the hillslope derived sediment is flushed through the system by early events which would occur because of exhaustion of hillslopes sediments q ssc relations are increasingly linear during later events in the rio panuco which is likely due to these events transporting a higher proportion of sediment entrained from the channel this is manifest by a reduction in lead times as the number of days between peak ssc and peak q for early and late events significantly decreases from 2 6 to 0 9 respectively large events 750 m3 s in the latter part of summer and early fall having high suspended sediment concentrations could be due to the replenishment of hillslope sediments or due to the contribution of sediment from source areas that were not previously exhausted the findings from this study are likely common to most drainage systems having seasonal bimodal streamflow regimes whereas the seasonal signature of q ssc relations is likely enhanced in those settings where agriculture is a major component of the landscape

river response to high frequency climate oscillations in southern europe over the past 200 k y a 200 k y chronology of river response to climate related environmental change has been established for northeast spain using newly developed luminescence dating techniques this constitutes the best documented record of late quaternary river behavior currently available for the north atlantic region and enables fluvial stratigraphies to be compared with high resolution ice core and marine oxygen isotope climate series pleistocene and holocene river aggradational episodes coincide with stadial or neoglacial events while phases of river incision occur during interstadial or interglacial periods alluviation and erosion cycles would appear to track variations in sediment supply controlled by vegetation cover and winter storm frequency

suspended sediment load during floods in a small stream of the dolomites northeastern italy abstract suspended sediment load was analyzed in a small high gradient stream of the eastern italian alps which was instrumented to measure discharge and sediment transport the ratio of suspended to total sediment yield and the relations between sediment concentration and water discharge were analyzed for seven floods which occurred from 1991 to 1996 in summer and autumn from june to october different patterns of hysteresis in the relation between suspended sediment and discharge were related to types and locations of active sediment sources the within storm variation of particle size of suspended sediment during a major flood indicates a coarsening of transported material for increasing discharge an analysis of grain size has shown that erosion areas on hillslopes were the main sources of suspended load

mid holocene tectonic geomorphology of northern crete deduced from a coastal sedimentary archive near rethymnon and a late bronze age santorini tsunamite candidate abstract the late bronze age lba tsunami and the a d 365 tsunami are supposed to have affected the northern coasts of crete however near coast sedimentary archives have been rarely investigated in this area and sedimentary archives including palaeotsunami fingerprints are still unknown the main objective of our research was to search for appropriate tsunami sediment traps in order to gain detailed insights into the holocene palaeotsunami history of northern crete we found an excellent fine sediment archive near pirgos located to the west of rethymnon based on a multi electrode geoelectrical survey and an 11 m deep sediment core we analysed the event geochronostratigraphical record by means of sedimentological geochemical geochronological geomorphological and microfossil investigations the pirgos record revealed a thick unit of homogeneous mud of a lagoonal environment starting 6000 years ago the lagoon was affected by five high energy events leaving layers of allochthonous sand microfossil analyses of these layers revealed a mixed foraminiferal assemblage including species from brackish habitats but also displaced and transported species from open marine and deep water environments considering sedimentary characteristics the local wave climate of the cretan sea and the overall geomorphological setting we interpret these layers as related to extreme wave events ewe based on a local radiocarbon age depth model we identified one ewe layer as a reliable candidate for the lba santorini tsunami another ewe layer is most probably associated with the a d 365 tsunami this ewe ended abruptly the lagoonal conditions at pirgos because of to the 1 64 m coseismic uplift at the site the pirgos lagoon existed between the first half of the 6th mill b c and at least the end of the 2nd mill b c we found that the area around pirgos has continuously subsided over 3000 or so years reflecting constant tectonogeomorphological conditions dominated by the nearby subduction zone between the aegean and african plates

longitudinal distribution and parameters of large wood in a mediterranean ephemeral stream abstract although large wood lw has been intensively studied in forested basins of humid temperate climates data on lw patterns in different fluvial environments are rather scarce therefore we investigated the dimensions characteristics longitudinal distribution and dynamics of lw along a 4 05 km long reach of an ephemeral channel typical of european mediterranean mountainous landscape sfakiano gorge crete greece we analysed a total of 795 lw pieces and the mean observed abundance of lw was generally lower 14 3 m3 ha of active valley floor or 19 6 lw pieces 100 m of stream length than is usually documented for more humid environments the number of lw pieces was primarily controlled by trees growing on the valley floor these living trees acted as important lw supply agents by tree throws or the supply of individual branches with sufficient lw dimensions and flow obstructions during large flood events causing storage of transported lw pieces in jams however the downstream transport of lw is probably episodic and large jams are likely formed only during major floods after 15 years we still observed significant imprints of the last major flood event on the present distribution of lw the geomorphic function of lw in the studied stream can only be perceived to be a spatially limited stabilising element for sediments which was documented by a few accumulations of coarse clastic material by lw steps and jams

spatial scale dependence of sediment dynamics in a gullied rolling loess region on the loess plateau in china sediment dynamics is still imperfectly understood especially at spatial scale in the highly erodible region of the loess plateau and few studies have been heretofore conducted using 5 year continuous water and sediment records three plots and three basins in the gullied rolling loess region were selected and sediment dynamics at spatial scale was studied results showed that the floods where the peak discharge qp did not come earlier than the sediment peak were predominant in slope zones occupying 90 and 70 of the total for the mao slope and for the entire slope respectively however in basins most of the sediment peaks cp lagged behind qp implying that slope zone was the main origin of sediment more than 50 of the events presented clockwise hysteresis loops in the mao slope area while almost all the events had anticlockwise hysteresis loops in basins this can be attributed to less occurring frequency of hyperconcentrated flow as well as its instability in slope zones compared to those in the basins within these contexts gravitational erosion made the highest sediment concentration c in tuanshangou basin and median developing status of c discharge c q relationships in the entire slope area this study provides insights into the protection of slope surface and disruption of the development of hyperconcentrated flow to reduce soil loss

sediment concentration versus water discharge during single hydrologic events in rivers relations between sediment concentration c and water discharge q for a hydrologic event such as a flood are studied qualitatively by analyzing smoothed temporal graphs discharge and concentration vs time in terms of mode spread and skewness comparing cq ratios at a given discharge on the rising and falling limbs of the discharge hydrograph provides a consistent reliable method for categorizing c q relations five common classes of such relations are single valued straight or curved clockwise loop counterclockwise loop single valued plus a loop and figure eight temporal graph mode and skewness influence the type of relation whereas temporal graph spread affects the details of the particular c q relation its graphical breadth shape orientation and plotted location field examples of the various types of relations are given including varieties that heretofore have received little attention such as the figure eight explanations for each type of c q relation are discussed

flood alluviation and entrenchment holocene valley floor development and transformation in the british uplands the morphology sedimentary properties and sequence of recent coarse grained flood deposits and earlier holocene alluvial fills were investigated in thinhope burn a small 12 km2 catchment in the northern pennine uplands northern england twenty one large flood events are recorded by distinctive cobble boulder bars sheets and splays and boulder berms and lobes lichenometric analysis showed that all but one of these floods dated from the mid eighteenth century the timing of large floods between 1766 and 1960 corresponds with major hydroclimatic trends evident in northern britain and northwest europe over this period discharge estimates suggest that flood magnitudes have decreased since the mid eighteenth century channel and flood plain metamorphosis in late roman times and in the eighteenth century following major valley floor entrenchment locally as much as 8 m would appear to have been caused by increased runoff and flood magnitude this was linked to a shift to a wetter climate with flow augmented by iron age and roman woodland clearance and drainage of the catchment in more recent times results from this study suggest that current models of longer term holocene and pleistocene valley floor development in the british uplands may need to be re evaluated

recent behaviour of the debeli namet glacier durmitor montenegro a small cirque glacier is present in a north east facing cirque on the mountain of sljeme 2455 m a s l in the durmitor massif montenegro sediment ridges in front of this glacier are interpreted as moraines and can be attributed to recent glacier activity over the past 130 years lichenometry was applied to determine the relative ages of different moraines using aspicilia calcarea agg one set of moraines dates from about 1878 ad whilst another set of inner moraines dates from about 1904 ad the most recent moraines appear to have formed within the last 11 years in front of an active glacier margin copyright 2007 john wiley sons ltd

fingerprinting suspended sediment sources in the catchment of the river ouse yorkshire uk statistically verified composite fingerprints and a multivariate mixing model have been employed to establish the main sources of the suspended sediment transported through the lower non tidal reaches of the river ouse and one of its main tributaries the river wharfe during the period 1994 1997 in the case of the suspended sediment samples collected from the river ouse the load weighted mean contributions from uncultivated topsoil cultivated topsoil and channel bank sources were estimated to be c 25 38 and 37 respectively while for the river wharfe these sources contributed c 70 4 and 23 respectively c 4 was derived from woodland topsoil suspended sediment samples collected during higher flows evidenced a greater contribution from channel banks than samples collected during lower flows source materials were also differentiated according to the three main geological source areas carboniferous permian and triassic and jurassic and their load weighted mean contributions were estimated to be c 24 41 and 35 for the river ouse and c 91 9 and 0 there are no jurassic rocks in this catchment for the river wharfe respectively when suspended sediment samples from tributary streams were used to characterize each geological source area the equivalent results for the river ouse were c 30 46 and 24 considering the three main tributaries that contribute to the river ouse the load weighted mean contributions from the rivers swale ure and nidd were estimated to be 82 15 and 3 respectively these values have been compared with estimates of the relative magnitude of the annual suspended sediment loads of these three rivers for the years 1995 and 1996 derived from continuous monitoring of discharge and turbidity differences between the two sets of results are ascribed to the different periods of record involved and to the timing of suspended sediment sampling relative to the overall storm hydrograph and thus the degree to which the available samples are representative of the overall suspended sediment flux although a number of limitations must be recognized the fingerprinting approach to source ascription is seen as providing valuable information regarding suspended sediment sources in the study catchments copyright 1999 john wiley sons ltd

trends and interannual oscillations in the main sea level surface pressure patterns over the mediterranean 1955 1990 the evolution of the main sea level pressure patterns built from rotated principal component analysis rpca over a domain centered on the mediterranean for the period 1955 1990 is examined the annual cycle and the interannual variations are analyzed using singular spectrum analysis ssa and three methods of spectral analysis to detect trends and oscillations in the main patterns the dominant patterns show oscillations characteristic of nao and so this paper shows that nao and so seem to be correlated in a band centered in 6 8 years and that slp behaviour over the region is dominated by qbo which controls the oscillation frequency while nao modulates the amplitudes

the influence of recent environmental change on flooding and sediment fluxes in the yorkshire ouse basin this study attempts to establish causes of historical variations in flood frequency and magnitude in a 119 year flood stage record at york and assess its likely effects on fluxes of fine sediment and associated base metal contaminants climatic controls of flooding are evaluated through analysis of synoptic flood generation and large scale land use changes are also considered in terms of their influence on food frequency and magnitude and sediment availability the late nineteenth century was characterized by low flood frequency and magnitude but as a consequence of upland metal mining contaminant concentrations and downstream fine sediment delivery would have been high a further decline in flood frequency and magnitude between 1904 and 1943 combined with the cessation of base metal mining resulted in a decline of sediment and contaminant fluxes between 1944 and 1968 increases in upland drainage changes in agricultural practices and high flood frequency and magnitude resulted in significantly enhanced sediment fluxes rates of flux declined between 1969 and 1977 owing to extremely low flood frequencies and magnitudes in the last two decades there have been a series of extreme magnitude floods which through remobilization of mining contaminated alluvium have resulted in high pollutant metal mining loads probably approaching those of the late nineteenth century in an historical context it appears that the lois monitoring programme has been undertaken in a period of extremely high flood frequency and magnitude in the uk and significantly enhanced sediment and contaminant metal flux analysis of synoptic flood generation suggests that any future increase in the frequency and vigour of cyclonic atmospheric circulations may result in a higher frequency of extreme floods and consequently increased sediment fluxes

the fluvial record of climate change fluvial landforms and sediments can be used to reconstruct past hydrological conditions over different time scales once allowance has been made for tectonic base level and human complications field stratigraphic evidence is explored here at three time scales the later pleistocene the holocene and the historical and instrumental period new data from a range of field studies demonstrate that croll milankovitch forcing dansgaard oeschger and heinrich events enhanced monsoon circulation millennial to centennial scale climate variability within the holocene probably associated with solar forcing and deep ocean circulation and flood event variability in recent centuries can all be discerned in the fluvial record although very significant advances have been made in river system and climate change research in recent years the potential of fluvial palaeohydrology has yet to be fully realized to the detriment of climatology public health resource management and river engineering

short term changes in the magnitude frequency and temporal distribution of floods in the eastern mediterranean region during the last 45 years nahal oren mt carmel israel short term changes in eastern mediterranean precipitation affecting flow regime were documented in nahal oren a 35 km 2 ephemeral stream in mt carmel a 500 m high mountain ridge located at the nw coast of israel the rainy winter of the mediterranean type climate csa in mt carmel is characterized by average annual rainfall of 550 mm at the coastal plain to 750 mm at the highest elevation while the summer is hot and dry stream flow generates after accumulated rainfall of 120 150 mm while large floods defined as flows with peak discharge of n 5m 3 s 1 and or n150 000 m 3 in volume are generated in response to rainfall of over 100 mm hence large floods in nahal oren stream occur not earlier than december precipitation and flow data were divided into two sub periods 1957 1969 and 1991 2003 and compared to each other the results indicate a clear increase in the frequency of large floods their magnitudes and volumes during the second period with no parallel change in the annual precipitation similarly an increase in storm rainfall runoff ratio from b5 to n15 and a decrease in the threshold rainfall for channel flow by 16 25 were documented these short term variations in flooding behavior are explained by the clear decrease in the length of the rainy season and by the resulting significant shortening in the duration of the dry spells the increase in the number of large rainfall events and the large floods in each hydrological year together with the increasing number of years with no floods indicate strengthening of their uncertainty of behavior

high resolution interpretative geomorphological mapping of river valley environments using airborne lidar data the availability of airborne lidar data provides a new opportunity to overcome some of the problems associated with traditional field based geomorphological mapping such as restrictions on access and constraints of time or cost the combination of airborne lidar data and gis technology facilitates the rapid production of geomorphological maps of floodplain environments however unfiltered lidar data which include vegetation and buildings are currently more suitable for geomorphological mapping than data that have been filtered to remove these features classification of lidar data according to elevation in a gis enables the user to identify and delineate geomorphological features in a manner similar to field mapping but it is necessary to use a range of classification intervals in order to map the various types of feature that occur within a single reach comparison of a lidar derived geomorphological map with an independently produced field geomorphological map showed a high degree of similarity between the results of the two methods although ground truthing is essential in cases where a high degree of accuracy is required ground truthing of a lidar derived geomorphological map showed that around 80 of features mapped using both methods were identified from the lidar data suggesting that the method is suitable for applications such as production of base maps for use in field mapping and selection of sites for detailed investigation copyright 2007 john wiley sons ltd

modelling hyperconcentrated flow in the yellow river a large amount of the total sediment load in the chinese yellow river is transported during hyperconcentrated floods these floods are characterized by very high suspended sediment concentrations and rapid morphological changes with alternating sedimentation and erosion in the main channel and persistent sedimentation on the floodplain however the physical mechanisms driving these hyperconcentrated floods are still poorly understood numerical modelling experiments of these floods reveal that sedimentation is largely caused by large vertical concentration gradients both in the channel during the rising stage of the flood as well as on the floodplains during a later stage of the flood these vertical concentration gradients are large because the turbulent mixing rates are reduced by the increased sediment induced density gradients resulting in a positive feedback mechanism that produces high deposition rates erosion prevails when the sediment is largely held in suspension due to hindered settling and is strengthened by the reduced wetted cross section caused by massive sedimentation on the floodplain observed patterns of erosion and sedimentation during these floods can be qualitatively reproduced with a numerical model in which sediment induced density effects and hindered settling are included copyright 2009 john wiley sons ltd

anti clockwise hysteresis in suspended sediment concentration during individual storms holbeck catchment yorkshire england abstract analysis of the flow sediment hysteresis shape may assist in determining the sediment source area in a small basin a clockwise hysteresis occurs when sediment is derived from the bed and banks of the channel or areas adjacent to the channel whereas an anti clockwise hysteresis occurs when the upper part of the slopes is the sediment source area

grain size characteristics of suspended sediment in the yellow river china abstract based on the data from the yellow river and its tributaries a systematic study has been made of the spatial and temporal variations in grain size feature of suspended sediment the grain size characteristics of suspended sediment in the yellow river basin are closely influenced by precipitation seasonal alternations of wind and water action and the nature of surface materials the lower the mean annual precipitation the stronger the wind action the coarser the surface loess materials the coarser is the suspended sediment in particular grain size characteristics of suspended sediment of the middle yellow river s tributaries are controlled by hyperconcentrated flows with suspended sediment concentrations of 300 000 400 000 mg l or more at a station the relationship between grain size and suspended sediment exhibits two peaks with percentages of the 0 05 mm suspended sediment occurring at both low and very high suspended sediment concentrations based on the data from all the tributaries of the middle yellow river an optimal grain size composition of suspended sediment has been identified that leads the annual suspended sediment concentration to the highest values the long term variation of grain size suspended sediment in the yellow river can be related to variations in precipitation and human activities the 30 year record from longmen station shows that during the 1960s the suspended sediment size increased but since the 1970s it has declined controlled by the influencing factors grain size of suspended sediment in the middle yellow river decreases from northwest to southeast

spatial scale dependence of sediment dynamics in a semi arid badland drainage basin abstract problems of spatial scale transference are of key interest in drainage basin research the objective of this study was to investigate the spatial scale dependence of sediment dynamics in semi arid badland drainage basins simulated rainfall experiments indicated that on microscale plots runoff generation and sediment entrainment occurred when total rainfall exceeded 0 5 to 6 mm on pediment surfaces 1 5 to 4 mm on sandstone surfaces and 8 to 25 mm on shale surfaces the sediment concentration discharge relationship for two mesoscale basins displayed a change from clockwise to counterclockwise hysteresis when total rainfall exceeded the threshold rainfall for the initiation of flow in deep tunnel systems the initiation of tunnel flow causes counterclockwise hysteresis due to a delayed increase in sediment concentrations during a runoff event this contrasts with the clockwise hysteresis caused by flushing in the early stages of runoff for smaller rainstorms comparison of micro and mesoscale sediment dynamics indicates that microscale thresholds are not by necessity in evidence at the mesoscale in addition at the mesoscale elements exist which are non existent at the microscale e g a deep tunnel system the behaviour of the mesoscale basin is dominated by these elements rather than by the microscale components it contains

large landslides and their effect on sediment flux in south westland new zealand landslides and runoff are dominant erosional agents in the tectonically active alpine south westland area of new zealand characterized by high uplift rates and extreme orographic precipitation despite a high density of shallow debris slides and flows the geomorphic imprints of deep seated bedrock failures are dominant and persistent over 50 large 1k m 2 landslides comprising rock slide avalanches complex rotational and rock block slides wedge failures and deep seated gravitational slope deformation were detected on air photos and shaded relief images major long term impacts on alpine rivers include 1 forced alluviation upstream of landslide dams 2 occlusion of gorges and triggering of secondary riparian landslides and 3 diversion of channels around deposits to form incised meandering gorges remnants of large prehistoric i e pre 1840 landslide deposits possibly represent the low frequency in terms of total area affected yet dominant end of the spectrum of mass wasting in the western southern alps this is at odds with high erosion rates in an active erosional landscape large landslides appear to have dual roles of supplying and retaining sediment the implications of these roles are that 1 previous models of shallow landslide derived sediment flux need to be recalibrated and 2 geomorphic effects of earthquake induced landsliding may persist for at least 10 2 years copyright 2005 john

a study of physico geographical factors for formation of hyperconcentrated flows in the loess plateau of china semi arid climate poor vegetation cover and highly erodible loess can be regarded as the main natural factors responsible for the formation of hyperconcentrated flows on the loess plateau china the degree to which the hyperconcentrated flows develop especially their extreme suspended concentration shows a significant areal differentiation this is closely related to the grainsize composition of suspended sediment an optimal grainsize composition of suspended sediment has been identified which leads to the highest value of extreme concentration among different river basins this optimal composition is related to the combination of three surface material types i e loess wind blown sand and weathered bedrock and it occurs as a result of seasonally alternating wind and water processes operating in this area

dynamics of suspended sediment delivery to the eastern mediterranean continental shelf this study provides data on the fluvial sediment transport at the eastern mediterranean an area in which the regional importance for comparative study has often been raised by investigators but the data are rather scarce we analysed long and short term hydrologic and sedimentological data from one of the largest coastal streams of israel qishon river 1100 km2 and its estuarine environment the results indicate that during 65 years 1944 2009 a total 140 floods have contributed to the sea an amount of approximately 2 58 106 tons of sediment during this period i the number of floods with a return period of more than 10 years has almost doubled during the last 30 years and ii the mean annual discharge during last 10 years increased by approximately 175 the analysis of the short 2 years hydrological and sediment data revealed that approximately 30 of the upstream channel loads do not reach the river mouth and are deposited along the channel bed even during major flood events this observation was attributed largely to the facts that the lower river bed is incised below sea level to the very low slopes and to the correspondingly low stream power and transport capacity the results of this study highlight the effect of interchannel dynamics as well as the constraints of interaction between fluvial system and estuarine processes on sediment transport copyright 2012 john wiley sons ltd

interpreting sediment delivery processes using suspended sediment discharge hysteresis patterns from nested upland catchments south eastern australia in this study suspended sediment concentration ssc and discharge q hysteresis patterns recorded at the outlets of two nested upland catchments in south eastern australia were examined detailed monitoring of sediment flux was undertaken in a 1 64 km2 sub catchment located within a 53 5 km2 catchment for which sediment yield was measured and the extent of incised channels mapped the analysis of ssc q hysteresis patterns was supplemented by these additional datasets to contribute to the explanation of observed patterns clockwise ssc q hysteresis loops with the suspended sediment peak leading the discharge peak were recorded most frequently at both sites this was attributed to initial rapid delivery of sediment from channel banks the dominant sediment source in the sub catchment and probably also for the catchment in conjunction with remobilization of in channel fine sediment deposits sediment exhaustion effects were considered to enhance clockwise hysteresis with reduced ssc on the falling limb of event hydrographs pronounced exhaustion effects were observed on some multi rise events with subsequent flow peaks associated with much reduced sediment peaks to compare ssc q hysteresis patterns between the two catchments a dimensionless similarity function sf was derived to differentiate paired event hysteresis patterns according to the extent of pattern similarity this analysis coupled with the other datasets provided insight into the function of erosion and sediment delivery processes across the spatial scales examined and indicated the dependency of between scale suspended sediment transfer on defined flow event scenarios quantitative measures of event ssc q hysteresis pattern similarity may provide a mechanism for linking the timing and magnitude of process response across spatial scales this may offer useful insights into the between scale linkage of dominant processes and the extent of downstream suspended sediment delivery copyright 2009 john wiley sons ltd

isostatic response of the australian lithosphere estimation of effective elastic thickness and anisotropy using multitaper spectral analysis gravity and topography provide important insights regarding the degree and mechanisms of isostatic compensation the azimuthally isotropic coherence function be tween the bouguer gravity anomaly and topography evolves from high to low for increasing wavenumber a diagnostic that can be predicted for a variety of lithospheric loading models and used in inversions for flexural rigidity thereof in this study we investigate the isostatic response of continental australia we consider the effects of directionally anisotropic plate strength on the coherelce the anisotropic coherence function is calculated for regions of australia that have distinctive geological and geophysical properties the coherence estimation is performed by the thomson multiple slepian taper spectral analysis method extended to two dimensional fields our analysis reveals the existence of flexural anisotropy in central australia indicative of a weaker n s direction of lower te this observation is consistent with the suggestion that the parallel faults in that area act to make the lithosphere weaker in the direction perpendicular to them it can also be related to the n s direction of maximum stress and possibly the presence of e w running zones weakened due to differential sediment burial rates we also demonstrate that the multitaper method has distinct advantages for computing the isotropic coherence function the ability to make many independent estimates of the isostatic response that are minimally affected by spectral leakage results in a coherence that is more robust than with modified periodogram methods particularly at low wavenumbers our analysis elucidates the reasons for discrepancies in previous estimates of effective elastic thickness te of the australian lithosphere in isotropic inversions for te we obtain values that are as much as a factor of 2 less than those obtained in standard inversions of the periodogram coherence using bouguer gravity and topography but greater than those obtained by inversions that utilize free air rather than bouguer gravity and ignore the presence of subsurface loads however owing to the low spectral power of the australian topography the uncertainty on any estimate of te is substantial

mass and hyperconcentrated flow deposits record dune damming and catastrophic breakthrough of ephemeral rivers skeleton coast erg namibia channel shaped deposits of well sorted sand with only 2 4 fine grained material being either massive and structureless or upward fining with basal lag are found interbedded with aeolian sand in the skeleton coast erg namibia detailed analyses of the channel shaped deposits suggest that they are formed as hyperconcentrated flows within the erg grain size analysis and whole rock geochemical modeling revealed that some of the fluvial sediments contain up to 70 aeolian sand interpreted as a result of dune collapse into the fluvial system in certain cases this instantaneous supply of sand resulted in generation of sandy mass flows with laminar flow behaviour the presence of smectite as dominant clay mineral proved to be of crucial importance in formation of mass flow deposits these mass flows had no erosional capacity and drape the palaeotopography they are comparable to those generated by catastrophic collapse of dunes described in the literature this paper suggests that all these deposits should be termed intra erg mass flows as several of them carry little if any debris based on their origin intra erg mass flows can be divided into two groups

hydro geomorphic hazards and impact of man made structures during the catastrophic flood of june 2000 in the upper guil catchment queyras southern french alps the guil river valley queyras southern french alps is prone to catastrophic floods as the long historical archives and holocene sedimentary records demonstrate in june 2000 the upper part of this valley was affected by a b30 yearq recurrence interval r i flood although of lower magnitude and somewhat different nature from that of 1957 n100 year r i flood the 2000 event induced serious damage to infrastructure and buildings on the valley floor use of methods including high resolution aerial photography multi date mapping hydraulic calculations and field observations made possible the characterisation of the geomorphic impacts on the guil river and its tributaries the total rainfall 260 mm in four days and maximum hourly intensity 17 3 mm h 1 aggravated by pre existing saturated soils explain the immediate response of the fluvial system and the subsequent destabilisation of slopes abundant water and sediment supply landsliding bank erosion particularly from small catchment basins cut into slaty schist bedrock resulted in destructive pulses of debris flow and hyperconcentrated flows the specific stream power of the guil and its tributaries was greater than the critical stream power thus explaining the abundant sediment transport the guil discharge was estimated as 180 m 3 s 1 at aiguilles compared to the annual mean discharge of 6 m 3 s 1 and a june mean discharge of 18 m 3 s 1 the impacts on the guil valley floor flooding aggradation generalised bank erosion and changes in the river pattern were widespread and locally influenced by variations in the floodplain slope and or channel geometry the stream partially reoccupied former channels abandoned or modified in their geometry by various structures built during the last four decades as exemplified by the aiguilles case study where the worst damage took place a comparative study of the geomorphic consequences of both the 1957 and 2000 floods shows that despite their poor maintenance the flood control structures built after the 1957 event were relatively efficient in contrast to unprotected places the comparison also demonstrates the role of land use changes conversion from traditional agro pastoral life to a ski hikingbased economy construction of various structures in reducing the guil channel capacity and more generally in increasing the vulnerability of the human installations the efficiency of the measures taken after the 2000 flood narrowing and digging out of the channel is also assessed final evaluation suggests that in such high mountainous environments there is a need to keep

implication of relationships among suspended sediment size water discharge and suspended sediment concentration the yellow river basin china according to the yearly maximum suspended sediment concentrations ssc in the yellow river and its tributaries the rivers are divided into three types of more than 300 20 300 and less than 20 kg m 3 the middle yellow river basin is located in the transitional zone from subhumid to semiarid climates and covered by a thick loess mantle neighboring on the desert areas to the northwest the surface material of the loess plateau exhibits some marked areal differentiation in grain size and forms three zones covered by sandy loess typical loess and clayey loess from northwest to southeast controlled by these physico geographical conditions the grain size of river transported sediment shows some particular characteristics at small water discharge or ssc the grain size of suspended sediment abruptly decreases to a minimum with increasing water discharge or ssc at water discharge of more than ca 40 m 3 s or at ssc of more than ca 40 kg m 3 the grain size increases with water discharge or ssc during the low stage season the relatively clear baseflow may scour the coarse bed materials so the suspended sediment is relatively coarse in the rainy season rainstorm runoff washes out fine loess materials to the river making suspended sediment fine during relatively strong rainstorms there often occur hyperconcentrated flows at ssc of more than 300 kg m 3 the relatively coarse grains could then remain suspended in the mixture of water and fine suspended sediment c 2002 elsevier science b v all rights reserved

temporal changes in suspended sediment transport in a gullied loess basin the lower chabagou creek on the loess plateau in china suspended sediment dynamics are still imperfectly understood especially in the loess hilly region on the loess plateau with strong temporal variability where few studies heretofore have been conducted using a dataset up to eight years long in the lower chabagou creek the variability in suspended sediment load at different temporal scales within flood variability monthly seasonal and annual is analyzed in this paper the results show that on the within flood scale most of the sediment peaks lag behind peak discharges implying that slope zones are the main sediment source area independent of the occurring sequences of the peaks of sediment and discharge all the events could present an anti clock wise hysteresis loop resulting from the abundant material and the influence of hyperconcentrated flows on suspended sediment concentration at monthly and seasonal scales there is a store release process i e sediment is prepared in winter spring and late autumn and exported in summer and early autumn at the annual scale the high variability in concentration and sediment yield are highly correlated with water yield resulting from the number and magnitude of floods recorded yearly and almost all the suspended load is transported during these events copyright c 2008 john wiley sons ltd

the suspended sediment dynamics in the inner mongolia reaches of the upper yellow river article i nfo suspended sediment dynamics are still imperfectly understood especially in the upper yellow river where few studies on this issue have been conducted this study analyzed the variability in suspended sediment concentration at different temporal scales within flood monthly seasonal and annual using a dataset up to 49 years long 1954 2002 at toudaoguai station this paper provided insight into the characteristics of suspended sediment transport in the ningxia inner mongolia reaches of the upper yellow river the results show that in a single flood event changes in ssc are not simultaneous with changes in discharge resulting in counterclockwise hysteretic loops clockwise loops or figure eight loops the c q loops and sediment rating curves for different seasons had different characters the diversiform c q loops in the inner mongolia reaches of the upper yellow river may be mainly caused by the sediment inputs from tributaries the differ ent propagation velocity of sediment and water discharge spatial and temporal storage depletion processes of available sediment at annual scale the variations of annual mean discharge and ssc displayed a similar gradually deceasing trend and the relation between water discharge and ssc during 1954 2002 could be de scribed by a cubic polynomial function since the joint operation of liujiaxia and longyangxia reservoirs after 1986 the transport capacity of the upper yellow river has been much reduced

geomorphological response to an extreme flood a case from southeast spain on 28 29 september 1980 an extreme storm of 150 mm of rain in c 5 hours caused a flash flood near tabernas in a semi arid area in southern spain with the rainfall total approximating the mean annual rainfall the recurrence interval is estimated to be 25 100 years flood peak discharges have been estimated from a mountain source area across an alluvial fan and the geomorphological response to the storm described channel adjustment differed between channels in the fanhead trench and those unconfined channels on the fan surface the implications of the spatial pattern of erosional an depositional feaures for landform adjustment in semi arid regions are discussed

scaling behaviour of vertical magnetic susceptibility and its fractal characterization an example from the german continental deep drilling project ktb the variations of rock magnetism reflect the geological inhomogeneities of the earth s crust i e its petrological mineralogical and structural organization the present state of the crust bears meaningful information of its past dynamic processes and evolution we analysed magnetic susceptibility data series from the boreholes of the german continental deep drilling project ktb by means of spectral and rescaled range r s analyses we could detect a scaling behaviour of magnetic data series and quantify it in fractal terms in particular the r s method yields more precise results than the fourier analysis and leads to hurst coefficients h 0 5 which means that the magnetic variations exhibit some persistence with depth because of the relation between rock magnetism and crustal features we suggest that the magnetic vertical inhomogeneities in the ktb area can be described by a self affine model with h 0 8 corresponding to a fractal dimension d 1 2

environmental magnetism as a dating proxy for recent overbank sediments of peri industrial regions in the czech republic and uk abstract twenty five floodplain sediment profiles from seven rivers in eastern czech republic and three in north west england were collected to examine the hypothesis that magnetic enhancement in recent sediments is predominantly of anthropogenic origin and that magnetic parameters can be used as a dating proxy reflecting changes in intensity of industry sources over time natural sources of magnetic enhancement were excluded and anthropogenic enhancement was identified as exhibiting elevated values of lf arm sirm sirm and s ratios with low values of fd magnetic spherules typically formed through fossil fuel combustion processes were observed by scanning electron microscopy sem in these sediments to assess the potential of magnetic parameters as a chronometer the approach was compared with frequently used dating techniques concentrations of heavy metals and 137 cs the floodplain profiles were divided to three groups according to the characteristics of their trends with depth in magnetic parameters lf in particular and the suitability of magnetic properties as a dating proxy group 1 which included the majority of the profiles exhibited magnetic enhancement in the upper part of its profiles and a single maximum in lf this group exhibited a clear suitability for our proposed magnetic dating as the magnetic record reflected the industrial history of the region and was aligned with the chronologies of the other dating techniques profiles magnetically enhanced throughout their depth and lacking any clear trend comprised group 2 here a mineral magnetic approach to dating was limited as the magnetic signal was diluted by a high sedimentation rate or impacted by local anthropogenic factors all profiles from england were included in group 3 because their magnetic depth profiles were influenced by natural sources of magnetic particles or specific sedimentary conditions and a longer industrial history and thus needed an individual interpretation however they still reflected the regional deposition history of industrial sources of ferrimagnetic particles overall magnetic parameters proved to be an efficient dating proxy with potential for recently aggrading rivers

flood stratigraphies in lake sediments a review abstract records of the frequency and magnitude of floods are needed on centennial or millennial timescales to place increases in their occurrence and intensity into a longer term context than is available from gauged river flow and historical records recent research has highlighted the potential for lake sediment sequences to act as a relatively untapped archive of high magnitude floods over these longer timescales abyssal lake sediments can record past floods in the form of coarser grained laminations that reflect the capacity for river flows with greater hydrodynamic energy to transport larger particles into the lake this paper presents a framework for investigating flood stratigraphies in lakes by reviewing the conditioning mechanisms in the lake and catchment outlining the key analytical techniques used to recover flood records and highlighting the importance of appropriate field site and methodology selection the processes of sediment movement from watershed to lake bed are complex meaning relationships between measureable sedimentary characteristics and associated river discharge are not always clear stratigraphical palaeoflood records are all affected to some degree by catchment conditioning fluvial connectivity sequencing of high flows delta dynamics as well as within lake processes including river plume dispersal sediment focussing re suspension and trapping efficiency with regard to analytical techniques the potential for direct e g laser granulometry and indirect e g geochemical elemental ratios measurements of particle size to reflect variations in river discharge is confirmed we recommend care when interpreting fine resolution geochemical data acquired via micro scale x ray fluorescence xrf core scanning due to variable down core water and organic matter content altering x ray attenuation we also recommend accounting for changes in sediment supply through time as new or differing sources of sediment release may affect the hydrodynamic relationship between particle size and or geochemistry with stream power where these processes are considered and suitable dating control is obtained discrete historical floods can be identified and characterised using palaeolimnological evidence we outline a protocol for selecting suitable lakes and coring sites that integrates environmental setting sediment transfer processes and depositional mechanisms to act as a rapid reference for future research into lacustrine palaeoflood records we also present an interpretational protocol illustrating the analytical techniques available to palaeoflood researchers to demonstrate their utility we review five case studies of palaeoflood reconstructions from lakes in geographically varied regions these show how lakes of different sizes and geomorphological contexts can produce comprehensive palaeoflood records these were achieved by consistently applying site validated direct and proxy grain size measurements well established chronologies validation of the proxy process interpretation and calibration of the palaeoflood record against instrumental or historical records