factors controlling hydro sedimentary response during runoff events in a rural catchment in the humid spanish zone abstract in galicia nw spain studies on the suspended sediment ss transported in river catchments are scarce using a dataset comprising three hydrological years 2004 05 2006 07 in the corbeira catchment nw spain the relationships between rainfall runoff and ss are analysed at event scale the catchment was instrumented to measure rainfall water level and ss in the stream several event rainfall discharge and ss concentration and load and pre event rainfall and discharge variables were calculated for all the events analysed correlation matrices were developed using these data discharge characteristics and rainfall depth showed good correlations with ss concentration and load suspended sediment and discharge relationships were also examined in most of the events the ss peak preceded peak discharge clockwise hysteresis implying that zones near the stream are the main sediment source areas

segmentation and coalescence of cenozoic carbonate platforms northwestern great bahama bank seismic profiles over the northwestern great bahama bank reveal that it is formed by the coalescence of three smaller platforms and significant lateral progradation this conclusion is contrary to previous models which assumed that the bank is the result of continuous accumulation on one huge buildup in late cretaceous to early tertiary time a north south trending depression the straits of andros separated an eastern platform andros bank from a western platform bimini bank initially the straits of andros had dimensions similar to the modem tongue of the ocean but was progressively filled from east to west in early to middle tertiary time a second depression the bimini embayment formed within bimini bank by folding it had a maximum depth of about 470 m this depression was also filled from east to west in addition prograding systems built the western margin of bimini bank more than 25 km westward into the straits of florida

progradation geometries of carbonate platforms examples from the triassic of the dolomites northern italy various types of progradation of triassic carbonate platforms are described from the dolomites of the southern alps the internal and external geometric relationships are exposed in spectacular natural sections and moreover their scale 500 1000 m of thickness is such that they can be compared with features found in seismic profiles the different types of progradation are controlled by a number of factors which normally interact with each other these factors include rate of basinal sedimentation rate of subsidence width of the platform depth of the surrounding basin and eustatic variations of sea level progradation is not a continuous process but episodic moments of massive debris input during which the platform advances alternate with long periods of negligible progradation during which basinal sediments accrete and onlap the toe of slope upper boundary relationships of the prograding platforms include offlap toplap and erosional truncation lower boundary relationships are horizontal climbing and descending progradations a variety of phenomena and circumstances have caused the cessation of progradation of the triassic platforms they include volcanism collapse of margins drowning rapid relative rise of sea level subaerial exposure relative fall of sea level and probably a natural decay of the system in the triassic of the dolomites two main progradation models can be put forward in the ladinian model progradation took place simultaneously with aggradation relative rise of sea level whereas the characteristic feature of the carnian model is toplap relative stillstand of sea level

model analyses of the contribution of in channel processes to sediment concentration hysteresis loops summary sediment concentration sc water discharge q relations in rivers are typically governed by multiple and relatively complex processes due to hysteresis effects sediment discharges can differ for similar or equivalent water discharges which causes scatter in empirical datasets and may decrease the predictive power of sc rating curves such hysteresis effects must therefore be understood and accounted for to make dependable predictions for river system management the overall objectives of this study are to develop modelling approaches suitable for reproducing and predicting hysteresis effects at larger scales and to investigate the possible contribution of in channel processes erosion and deposition to sediment concentration hysteresis loops to investigate relevant field scale conditions we develop a one dimensional dynamic sediment transport model of the downstream tuul river northern mongolia investigating in channel processes along a 141 km stretch during a hydrological year the results show that the present modelling approach can reproduce both anti clockwise and clockwise hysteresis effects importantly in channel processes alone can cause considerable anti clockwise hysteresis effects without being reinforced by catchment processes such as hillslope erosion such specific contributions from in channel processes introduced data scatter into the sediment rating curves decreasing their r 2 values from unity to approximately 0 5 to 0 6 more generally possible changes in the number or magnitude of high flow events caused by climatic or other anthropogenic factors could influence total sediment deposition which was primarily found to occur during relatively short high flow events such potential changes also have important implications for the possible spreading of polluted sediments

relationships among rainfall runoff and suspended sediment in a small catchment with badlands abstract the araguas catchment of the central spanish pyrenees has been monitored since 2004 to study weathering erosion and the hydrological and sediment response to rainfall events in order to understand the hydromorphological dynamics of a badland area in a relatively humid environment this small catchment 0 45 km2 shows highly active processes of physical and chemical weathering related to seasonal variations in temperature and moisture erosion and sediment transport are widely studied in badlands within mediterranean environments because they represent the dominant sediment source to obtain information about suspended sediment and discharge a gauging station was installed within the araguas catchment during the summer of 2005 the aim of this work is to determine the relationships among rainfall runoff and suspended sediment in this badland area towards this goal we analyze the relationships between suspended sediment concentration and discharge during rainfall events from a hydrological viewpoint the araguas catchment reacts to all rainfall events with torrential flow being the most characteristic hydrological response the results obtained between october 2005 and april 2007 reveal extremely high concentrations of suspended sediment with values frequently exceeding 100 g l 1 and reaching a maximum of 1200 g l 1 three different types of hysteretic loops were observed clockwise 22 events 28 counter clockwise 27 events 34 and figure eight 12 events 15 moreover 23 of events were classified as complex hysteretic loops and removed from the analysis due to their complexity clockwise hysteretic floods are characterized by their long duration and the highest hydrological and sedimentological responses counter clockwise hysteretic floods are characterized by their short duration and moderate hydrological and sediment responses finally figure eight hysteretic floods are related to multiple peaks in suspended sediment coinciding with oscillations in discharge associated with the highest rainfall intensities within each event and moderate hydrological and sediment responses

the evidence for paraglacial sedimentation and its temporal scale in the deglacierizing basin of small river glacier canada abstract spatially sampled suspended sediment data from extra channel surfaces of different ages during rainfall events were used to infer the timescale of landscape adjustment to little ice age lia deglacierization at small river glacier canada surface ages were determined by aerial photograph interpretation turbidimeters were installed in three ephemeral channels on young mature and old surfaces and their response to rainfall events of different magnitudes recorded results showed young ice proximal surfaces exposed since 1977 were increasingly vulnerable to mobilization during rainfall events a suspended sediment response from old surfaces exposed since 1910 was recorded for only three events with 5 and 30 year return periods the intensity and duration of rainfall events therefore had to increase in magnitude to mobilize sediment on surfaces of increasing maturity hysteresis in the channel suspended sediment response further confirmed the dependence of surface response on rainfall event magnitude the rapid temporal decline in surface response indicated that surface armoring or sediment exhaustion is stabilizing surfaces within decades of exposure from the lia maximum ca 1910 at small river glacier however further perturbation for example by glacial advance or extreme climatic events would likely modify the pattern of suspended sediment yields by changing terrain surface mobilization thresholds and reconfiguring channel sediment stores we therefore suggest that it is difficult to determine when paraglacial sedimentation ceases to influence suspended sediment yields and therefore significantly limiting the usefulness of the term to describe the period of suspended sediment yield adjustment following deglacierization

new tools for seismic stratigraphic interpretation stratal convergence and instantaneous isochron attribute cubes derived from volumetric flattening of experimental strata interpreting seismic data requires inferences to be made from the geometry character and spatial association of seismic reflections seismic attributes that highlight such associations are essential for understanding basin fill histories in this article we describe two novel attributes obtained from an automatic full volume flattening algorithm and apply them to a synthetic seismic volume of experimental strata the stratal convergence attribute colors reflections according to their degree of convergence which is commonly high in areas where strata thin because of erosion or nondeposition the instantaneous isochron attribute measures thickness between reflections and is therefore generally proportional to sediment accumulation rate these attributes distinguish bounding surfaces and depocenter migration in well constrained experimental strata by showing the diagnostic value of each attribute our study motivates field based applications of full volume flattening and attribute co rendering for seismic stratigraphic interpretation

tracing sediment sources during floods using diffuse reflectance infrared fourier transform spectrometry drifts a case study in a highly erosive mountainous catchment southern french alps summary in mountainous catchments large quantities of sediment are exported within very short periods leading to numerous environmental problems e g reservoir siltation the origin of suspended sediment during two distinct floods was determined by conducting an original fingerprinting method coupling diffuse reflectance infrared fourier transform spectroscopy drifts and a chemometric technique i e partial least squares pls analysis samples of the potential sediment sources were collected in badland areas developed on various substrates i e molasse marly limestones black marls and gypsum in the galabre 20 km 2 catchment located in the french southern alps drifts spectra provided a way to discriminate between the different potential sediment sources furthermore the use of mid infrared spectra allowed the direct quantification of the gypsum proportion in sediment this contribution was systematically null at the catchment outlet because of the rapid dissolution of gypsum in the river a pls model was then constructed to estimate the contribution of the three other potential sources to the sediment flux during the floods this model was developed and validated using a set of 45 experimental samples that were prepared in the laboratory in order to contain various proportions of the three remaining sources by introducing drifts spectra into the pls model we could predict the proportions of those sources in the mixed experimental samples with a confidence interval of ca 10 the model was then applied to the sediment collected during the two selected floods in order to outline their origin black marls provided the highest contribution of sediment during both events but the analysis also revealed a significant contribution of molasse results also showed the remobilisation of sediment originated from molassic substrates that deposited on the riverbed during a preceding event opportunities for improvement and further use of this method as an alternative or rapid complementary sediment fingerprinting technique are finally discussed

hydroclimatic and channel snowpack controls over suspended sediment and grain size transport in a high arctic catchment temporal variability in suspended sediment delivery processes was studied during three seasons in a 7 9 km2 catchment at cape bounty melville island nunavut in the canadian high arctic discharge was controlled primarily by the magnitude of snowmelt with limited inputs from ground ice melt and precipitation years with greater snowpack non linearly increased sediment yield and resulted in seasonal counter clockwise hysteresis while a year with low snowpack resulted in reduced sediment yield and clockwise hysteresis and indicates that sediment was increasingly available after the onset of streamflow in addition to the event scale hysteresis observed during the nival discharge peak diurnal clockwise hysteresis was observed during all three seasons and suggests daily exhaustion of sediment supplies these results indicate that the channel snowpack plays a primary role over sediment accessibility during the nival discharge peak similarly grain size analysis of suspended material in the river showed that the coarsest mean grain size was transported during the early phase of peak nival discharge and indicates that isolated sources of coarse material were being accessed by high velocity flow snowpack is present through the peak nival period and conditions sediment availability by isolating channel sediments from high energy flow these results indicate sediment delivery characteristics in small high arctic catchments reflect complex interactions with channel snowpack and disproportionate responses to flow conditions that differ from glacial and temperate settings copyright 2008 john wiley sons ltd

determining sediment source areas in a tropical river basin costa rica abstract four hydrologic events were studied at three gauging stations in the pejibaye river basin costa rica the sediment sources were determined by comparing the timing of the sedigraph at the gauging station and the timing of rainfall in the catchment with addition of time for the new water to flow from different land use districts along the main rivers to the gauging stations the rainfall was recorded in the basin upstream of pejibaye gauging station which was therefore the only station where the sedigraph rainfall method could be properly used for determining sediment sources on three occasions the sediment discharges at the pejibaye station were of about equal height the sedigraph rainfall method indicated that on two of these occasions the sediment came mainly from the pasture and sugar districts and in one case from the forested middle basin on the fourth occasion rainfall amounts and intensities were locally high in the forested upper basin but water and sediment discharges were small re erosion of material deposited in the channel increased the width of clockwise sediment concentration discharge loops in one storm the concentration discharge loop changed from an eight shaped loop at the upper station to a counter clockwise loop at the downstream station explained by the lagging of the sediment after the water

suspended sediment transport regime in a debris flow gully on vancouver island british columbia in debris flow prone channels normal fluvial sediment transport occurs nearly exclusively in suspended mode between episodic debris flow events observations of suspended sediment transport through a winter season in a steepland gully in logged terrain revealed two event types when flows exceeded a threshold of 270 l s 1 events yielded significant quantities of sediment and suspended sediment concentration increased with flow smaller events were strongly supply limited sediment concentration decreased as flow increased overall there is no consistent correlation between runoff and sediment yield within the season three subseasons were identified demarcated by periods of freezing weather within which a pattern of fine sediment replenishment and evacuation occurred finally a signature of fine sediment mobilization and exhaustion was observed within individual events fine sediment transport occurred in discrete pulses within storm periods most of the yield occurring within 5 to 15 of storm runoff duration so that it is unlikely that scheduled sampling programs would identify significant transport significant events are however generally forecastable on the basis of regional heavy rainfall warnings providing a basis for targeted observations radiative snowmelt events and rain on snow remain difficult to forecast since the projection of temperatures from the nearest regular weather station yields variable results copyright 2004 john wiley sons ltd

discharge and suspended sediment patterns in a small mountainous watershed with widely distributed rock fragments summary understanding and quantifying sediment loads is important in watersheds with highly erodible materials which will eventually cause environmental and ecological problems within this context suspended sediment ss transport and its temporal dynamics were studied in a small mountainous watershed with sloping lands containing rock fragments in subtropical china soils containing rock fragments with many macro pores have a high permeability rate over a 7 year period the mean runoff coefficient of this watershed was 0 65 overall 30 flood events were monitored and accounted for 95 5 27 3 17 1 of the total ss load precipitation and total discharge respectively over a 5 year period the presence of rock fragments in soils can affect soil loss when comparing the soil loss in the studied watershed with that of other watersheds under similar climatic conditions rock fragments negatively affect soil loss however an extreme event occurred on 14 august 1990 and the sediment load exhibited a phenomenon called small deposits towards lump withdrawal which resulted in a soil loss of 20 499 t 4 6 times the mean yearly soil loss this event exhausted most of the ss s stored by the rock fragments on the slope and channel following this event the mean ss concentration ssc of the 11 events was 1 05 kg m 3 and the mean ssc of the 18 previous events was 1 75 kg m 3 twelve variables were separated using the classical hydrograph separation method partial least squares regression plsr was used to determine the highly co related variables of the discharge the results indicated that plsr could explain runoff well the relationship between discharge and ssc was highly scattered during 24 flood events three types of hysteresis loops were observed clockwise 17 events figure eight 3 events and complex 4 events

event based suspended sediment dynamics in a central new york watershed abstract using discharge and sediment data collected from 23 events between 2008 and 2010 in a 311 km2 watershed of central new york we investigated event sediment dynamics of the studied watershed after showing the statistical difference of the data in different seasons we examined the detailed hysteresis patterns of all events spring events had figure eight with anticlockwise figure 8 ac clockwise c anticlockwise ac and complicated patterns summer events had c ac figure 8 ac figure 8 c and complicated patterns fall and winter events had the same patterns as those in summer as well as a weak loop pattern the diversity of patterns within and between seasons suggests that detailed processes of sediment transport were not only complicated during one event but also varied from season to season although hysteresis analysis failed to identify these detailed processes and the associated sediment sources in such a relatively large watershed it successfully revealed a common feature dominating the transport processes event sediment transport was generally supply limited further analysis on the correlation between event sediment yield ssye and event peak discharge qpeak indicated that i events with clockwise patterns tended to have more ssye than those with other patterns for the same qpeak and ii data from all events may be statistically well described by a single ssye qpeak equation regardless of hysteresis patterns this equation i reveals that complicated event transport processes may be lumped into a simple process over events and ii reflects the general supply limited nature identified by hysteresis analysis using this equation and the magnitude frequency analysis we further discovered that in the past 21 years sediment was mainly transported by more frequent but relatively small discharges with the recurrence interval no more than 0 5 year

gully erosion and sediment transport in a small subtropical catchment south china discharge and sediment concentration were monitored at two dams as well as gully erosion at four locations during 1988 1989 in the shenchong experimental basin 0 73 km2 located in subtropical deqing county guangdong province the temporal pattern of sediment concentration at the basin outlet is closely related to gully discharge and due to the proximity of the gully sediment source to the gauging station the hysteresis pattern at the lower dam is dominantly clockwise discharge thresholds exist in the sediment concentration discharge relationships at both the upper and the lower dams at the upper dam they are related to the presence of local wetlands which act as a buffer to sediment transport in the channel at the lower dam they result from variable sources of sediment as well as early flow cessation in gullies computation of sediment yield from gullies confirms that they accounted for over 85 of the sediment load that passed through the lower dam

post fire hydrological response and suspended sediment transport of a terraced mediterranean catchment in july 2013 a wildfire severely affected the western part of the island of mallorca spain during the first three post fire hydrological years when the window of disturbance tends to be more open the hydrological and sediment delivery processes and dynamics were assessed in a representative catchment intensively shaped by terracing that covered 37 of its surface area a nested approach was applied with two gauging stations covering 1 2 km2 and 4 8 km2 built in september 2013 that took continuous measurements of rainfall water and sediment yield average suspended sediment concentration 1 503 mg l 1 and the maximum peak 33 618 mg l 1 were two orders of magnitude higher than those obtained in non burned terraced catchments of mallorca this factor may be related to changes in soils and the massive incorporation of ash into the suspended sediment flux during the most extreme post fire event 50 mm of rainfall in 15 minutes reaching an erosivity of 2 886 mj mm ha 1 h 1 moreover hysteretic counter clockwise loops were predominant 60 probably related to the increased sensitivity of the landscape after wildfire perturbation though the study period was average in terms of total annual precipitation even higher in intensities minimal runoff 2 and low sediment yield 6 3 t km 2 y 1 illustrated how the intrinsic characteristics of the catchment i e calcareous soils terraces and the application of post fire measures limited the hydrosedimentary response despite the wildfire impact

strand plain evidence for late holocene lake level variations in lake michigan lake level is a primary control on shoreline behavior in lake michigan the historical record from lake level gauges is the most accurate source of information on past lake levels but the short duration of the record does not permit the recognition of long term patterns of lake level change longer than a decade or two to extend the record of lake level change the internal architecture and timing of development of five strand plains of late holocene beach ridges along the lake michigan coastline were studied relative lake level curves for each site were constructed by determining the elevation of foreshore swash zone sediments in the beach ridges and by dating basal wetland sediments in the swales between ridges these curves detect long term 30 yr lake level variations and differential isostatic adjustments over the past 4700 yr at a greater resolution than achieved by other studies the average timing of beach ridge development for all sites is between 29 and 38 yr ridge this correspondence occurs in spite of the embayments containing the strand plains being different in size orientation hydrographic regime and available sediment type and caliber if not coincidental all sites responded to a lake level fluctuation of a little more than three decades in duration and a range of 0 5 to 0 6 m most pronounced in the relative lake level curves is a fluctuation of 120 180 yr in duration this 150 yr variation is defined by groups of four to six ridges that show a rise and fall in foreshore elevations of 0 5 to 1 5 m within the group the 150 yr variation can be correlated between sites in the lake michigan basin the 30 and 150 yr fluctuations are superimposed on a long term loss of water to the lake michigan basin and differential rates of isostatic adjustment

relationships between suspended sediment concentrations and discharge in two small research basins in a mountainous mediterranean area vallcebre eastern pyrenees abstract the relationships between suspended sediment concentrations and discharge were studied at the can vila 0 56 km2 and ca l isard 1 32 km2 sub basins of the vallcebre research area eastern pyrenees during a period of 5 years that included 67 events of diverse magnitude abandoned agricultural fields and forests are the main land use in the can vila basin whereas the ca l isard basin is mainly forested though there are also some heavily eroded landscapes badlands the most frequent events were of a single discharge peak although double and multiple peaked events were also recorded clockwise positive hysteretic loops occurred in both catchments mainly during the wet seasons when precipitation was of moderate intensity average of 18 mm h 1 and baseflow before the event was rather high average for ca l isard 8 1 l s 1 km 2 and for can vila 11 76 l s 1 km 2 the bulk of stream discharge came from saturated areas whereas sediments came mainly from the stream channels counter clockwise negative hysteretic loops were much more frequent in the ca l isard basin mainly in summer when rainfall intensity was high average of 32 5 mm h 1 and baseflow was low average for ca l isard 0 94 l s 1 km 2 and for can vila 0 73 l s 1 km 2 most of the water and sediment came from the badlands eight shaped loops occurred in transition periods mainly in the ca l isard basin

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

drivers of erosion and suspended sediment transport in three headwater catchments of the mexican central highlands quantifying suspended sediment exports from catchments and understanding suspended sediment dynamics within river networks is important especially in areas draining erodible material that contributes to the siltation of downstream reservoirs and to the degradation of water quality a one year continuous monitoring study of water and sediment fluxes was conducted in three upland subcatchments 3 0 9 3 and 12 0 km2 located within the cointzio basin in the central volcanic highlands of mexico michoacan state two subcatchments generated high sediment exports i e huertitas 900 1500 t km 2 y 1 and potrerillos 600 800 t km 2 y 1 whereas the third subcatchment was characterized by a much lower sediment yield i e la cortina 30 t km 2 y 1 such disparities in subcatchment behaviours were associated with the presence of severely gullied areas in huertitas and potrerillos rather than with rainfall erosivity indices an adapted classification of hysteretic patterns between suspended sediment concentration ssc and discharge was proposed because 42 of flood events contributing to 70 of sediment export were not discriminated by the classical clockwise anticlockwise typology this new classification allowed the identification of relationships in the hydrosedimentary responses of successive floods a stream transport capacity limit was also detected during hydrograph recession phases overall hydrosedimentary processes proved to be seasonally dependent sediment export was repeatedly limited by the stream transport capacity during the first part of the rainy season whereas a channel minimum erosivity threshold was frequently reached at the end of the season

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

the contribution of aeolian processes to fluvial sediment yield from a desert watershed in the ordos plateau china in arid zones many active aeolian dunes terminate at ephemeral and perennial desert rivers the desert rivers show very high rates of sediment transport that cause deleterious downstream effects on the river system and ecology high sediment loading has been attributed to severe water erosion of sparsely covered watersheds during infrequent but heavy rainfall although aeolian erosion is known to lead to high rates of wind blown sand transport direct confirmation of whether the aeolian processes accelerate or inhibit fluvial sediment loss is lacking here we show that an aeolian fluvial cycling process is responsible for the high rate of suspended sediment transport in a sudalaer ephemeral desert channel in the ordos plateau of china frequent aeolian processes but low frequency once every 3 years on average flooding occur in this region wind blown saltating grains appeared to be unable to cross the desert channel because of interruption of channel induced recirculating air flow and therefore tended to settle in the channel during the windy seasons leading to channel narrowing during flooding this narrowed channel was found to yield a threefold increase in suspended sediment loading and a 3 4 fold increase in the weight percentage of the 0 08 0 2 mm sediment fraction on 18 july 2012 loss of stored aeolian sand due to channel erosion accounted for about half of the total sediment yield in this watershed these findings show that aeolian processes play an essential role in accelerating the sediment yield from a watershed characterized by aeolian fluvial interplay and also suggest that the drier the region and the greater the aeolian process the more the aeolian process contributes to fluvial sediment yield copyright 2013 john wiley sons ltd

effect of seasonal snow cover on suspended sediment runoff in a mountainous catchment summary the effect of snow cover and snowmelt on suspended sediment ss runoff at a mountainous catchment in the temperate zone was investigated the observation was carried out from march 1999 to may 2002 3 years at an experimental catchment with the area of 0 347 km 2 ranging from 280 m to 618 m above mean sea level with average stream gradient of 1 4 it was concluded that the snow accumulation and ablation process in the catchment had a significant impact on ss runoff characteristics especially during the snow melting period it was estimated that more than 60 of the annual ss load flowed out during the snow melting period because of the enhanced water discharge the daily average ss flux during the snow melting period was calculated to be 2 54 g s 1 km 2 corresponding to a 6 7 times greater ss flux than that during other periods the c q relation analysis in each runoff event revealed a dynamic change in the ss runoff mechanism during the snow melting period strong clockwise hysteresis in c q relation in the early stage of the snow melting period may be explained by consumption of the bed load by the first flush followed by quick depletion of the material on the stream bed due to suppression of further ss supply by thick snow cover counterclockwise hysteresis in c q relation was observed only in the late stage of the snow melting period ss production at steep slopes beside the stream by avalanches and surface soil slides induced by an abundance of meltwater was considered to be one of the main causes of the counterclockwise loops it would be hypothesized that exposure of other steep slopes or bluffs in the catchment apart from the stream and stream bank failure by repeating surges of the stream water stage could also be other possible ss sources causing counterclockwise hysteresis in the late snow melting period

a graphical method to study suspended sediment dynamics during flood events in the wadi sebdou nw algeria 1973 2004 small sub basins are numerous in mediterranean area and global sedimentary budgets cannot be obtained without a detailed understanding of the hydroclimatic processes that govern sediment fluxes in these small river systems in this study the shape of the relationship between sediment concentration c and water discharge q during flood events of a 31 years period 1973 2004 was analyzed at the outlet of the wadi sebdou basin 256 km2 in northwest algeria using a new graphical analysis method based on features of hysteresis loops each flood was decomposed as successive stages each of which being characterized by a sediment rating curve and used to quantify the contribution of diverse sediment sources within the basin seven common classes of hydrological events single valued and six hysteresis loops clockwise counter clockwise eight shaped single valued plus one loop either clockwise or counter clockwise and single valued plus at least two loops were explored sediment supply from locally derived sources or base load was high and reached 77 of total sediment yield for the study period and was attributed to weathering of bed material or gullies the remainder portion was derived from hill slopes re suspension of fresh fine deposits in the river bed or bank collapse the ratio of suspended sediment load derived from active sediment source varies considerably from one flood to another depending on many factors such as seasonality and antecedent type of flood the simpler floods were the most frequent ones but produced less sediment the most frequent floods were clockwise or anticlockwise 52 of floods but brought only 34 of the total sediment flux the 18 of the most complex floods single valued plus at least two loops produced more than 53 of the sediments mainly supplied by base load 84 intra annual variability was very high over 31 years the five biggest floods cumulated 64 of the total sediment flux and were of three classes the most complex floods being dominant the largest contribution occurred during one single 33 days long hydrological event with complex form which represented 26 of the total sediment flux apart from the five biggest flood events the base load represented 53 the biggest floods favour base load as compared to the smallest ones

rapid strand plain accretion in the northeastern nile delta in the 9th century a d and the demise of the port of pelusium an unusually large 1 km 3 and rapid influx of nile river sediment in the early 800s a d resulted in accretion of an extensive strand plain 6 to 15 m thick 35 km long and as much as 12 km wide on the subsiding northeastern nile delta margin egypt this event is related to blockage of the pelusiac branch and breaking through of a new distributary to the west of present day port said probably representing initiation of the damietta branch the sand is of analytically identical age throughout the area and was deposited within less than 60 yr as indicated by 14 c and amino acid racemization analyses of donax shells from a series of cores radiocarbon dates in combination with historical accounts by al jakubi who found the strand plain already in existence when he visited the area in the late 800s place this event in the early 800s nilometer flood records suggest that the sequence of great floods of 813 816 and 820 may have been the triggering events this sudden displacement of sand caused pelusium then the principal port and fortified city of the northeastern nile delta located at the mouth of the pelusiac branch to be cut off from both the nile and the mediterranean and led to its decline and eventual abandonment by the 12th century when the crusaders arrived

sediment export by water from an agricultural catchment in the loam belt of central belgium abstract an agricultural drainage basin of 250 ha was selected in the belgian loam belt to evaluate sediment export by water water discharge was continuously measured at the outlet of the catchment and suspended sediment samples were taken proportional with discharge during rainfall events from these samples supended sediment concentration and grain size distribution were determined within the catchment regular surveys were conducted in order to obtain detailed data on vegetation cover soil surface parameters and erosion and sedimentation features important variations in sediment yield were detected at various time scales ranging from a year over a season to one event these variations could be linked with processes occurring within the catchment due to the development of a vegetation cover the suspended sediment concentrations were lower during the summer period than during the winter period for the same discharge the evolution in both suspended sediment concentration and grain size distribution during the winter period is explained by variations in the soil surface state of the fields as well as the development of a rill and gully network the positive hysteresis observed within a single event is explained by taking into account the distance between the sediment source and the catchment outlet and not by sediment flushing our analysis shows that the role of the main factors controlling the geomorphic response of such a catchment can be identified only if measurements at the outlet are complemented by detailed data on the conditions within the catchment catchment model calibration and validation are therefore impossible if this information is lacking

seasonal patterns of suspended sediment transport in an abandoned farmland catchment in the central spanish pyrenees the suspended sediment response of a small catchment subjected to farmland abandonment and subsequent plant recolonization was studied in relation to its hydrological functioning the analysis of data over a seven year period demonstrated that suspended sediment yield was greatly influenced by the occurrence of intense low frequency events greater amounts of suspended sediment were exported during spring when the catchment was hydrologically more active rainfall intensity and baseflow at the start of a flood event had a strong influence on the sediment response suggesting that several hydrological processes were active within the catchment ssc suspended sediment concentration q hysteretic loop analysis at the event scale aided understanding of the sedimentological and hydrological behaviour of the catchment during the study period the ssc q loops showed a high degree of seasonality and two main patterns strongly related to catchment wetness were distinguished when the catchment was dry mainly during summer and the beginning of autumn the predominant process was infiltration excess runoff over sparsely vegetated areas close to the main channel under these conditions floods exhibited a counter clockwise hysteretic loop and were characterized by a small streamflow response short duration and high ssc under wet conditions mainly during winter and spring saturation excess runoff was increasingly dominant over vegetated areas under these conditions floods exhibited a clockwise hysteretic loop and were characterized by a larger streamflow response longer duration and higher suspended sediment yield the lower ssc during the falling stage of the hydrograph is likely to be due to dilution effects related to the contribution of clean water resulting from enlargement of the saturated areas together with an increase in the baseflow discharge 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

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

a depositional model for spherulitic carbonates associated with alkaline volcanic lakes the south atlantic aptian pre salt reservoirs are formed by a combination of spherulitic carbonates and mg rich clays accumulated in volcanic alkaline lake settings with exotic chemistries so far outcrop analogues characterised by metre thick successions deposited in lacustrine scenarios are elusive so disentangling the genesis of spherulitic carbonates represents a major scientific challenge with business impact in particular the controls on spatial distribution and the environment of spherulitic facies formation remain poorly constrained little studied and hotly debated to shed light on this conundrum a spherulitic carbonate rich alkaline volcanic lacustrine succession has been analysed at outcrop scale the carboniferous east kirkton limestone scotland despite clays being very scarce and limited to layers of amorphous mg si minerals a diverse array of spherulitic calcitic components were formed including coated grains crusts and build ups this setting enables the mechanisms of spherulitic calcite development and the patterns of sediment accumulation to be explored in a geobiological and hydrochemical scenario similar to the pre salt subsurface occurrences but divorced from clay influence the integration of logs borehole data outcrop photomosaics and petrographic observations collectively allowed the reconstruction of a depositional model for the east kirkton lacustrine succession in this model calcite spherule nucleation took place at the sediment water interface in the littoral zone driven by the co occurrence of 1 high alkalinity 2 ca mg rich hydrochemistry and 3 microbial derived colloidal exopolymeric substances these environmental conditions permitted the coeval development of spherulitic cementstone build ups and spherulitic grainstone packstone within the wave agitated zone and the accumulation of floatstones and laminites of spherulitic grains in deeper lake regions by means of downslope reworking this model is consistent with the previously documented microbial bloom occurrences and highlights the need to better understand the complex microbe solution interactions before any reliable facies model is envisaged

major and trace element partition and fluxes in the rhone river dissolved and particulate major and trace element concentrations and suspended particulate contents were determined during three years on the lower rhone river france from subsurface water samples collected about twice a month and more regularly during flood events dissolved elements can be grouped into two sets showing similar relationship between concentration and water discharge related to dilution process and to local and diffuse inputs of dissolved elements in the rhone basin the variation of no 3 na and cl na ratios and the absence of correlation between no 3 and the enrichment in cl show that rhone river is not highly affected by fertilizer applications compared to other large french rivers seine and loire rivers in particulate phase ca sr u pb bi cd sb and zn displayed high enrichment factors over shale composition lead bi cd and zn enrichment could be related to the anthropogenic inputs while ca sr and u enrichment was explained by lithological composition of the rhone basin dominated by carbonate rocks distribution coefficients of elements kd are relatively stable with however some variations with increasing spm concentrations these variations were attributed to local and diffuse inputs and to a higher contribution of carbonate bedrock in the rhone basin during flood events dissolved and particulate major and trace elements and suspended particulate matter spm fluxes of the rhone river to the mediterranean sea were estimated for the period 2001 2003 spm and particulate element fluxes were highly dependent on flood events 69 to 91 of the annual fluxes were exported in less than 12 of the time rhone river inputs were the principal source of particulate elements except for cd and zn in the northwestern mediterranean sea while the major part of dissolved elements were carried out by atmospheric inputs except dissolved as for which rhone river contributed to more than 50 of the input to the marine system

hydrologic controls on wash load sediment concentrations within a low ordered ephemeral watershed summary this study explores the influence of rainfall and runoff production on wash load sediment transport in a low order ephemeral watershed in southeast arizona wash load concentrations measured at the watershed outlet generally decreased throughout a runoff event and were better correlated with the rainfall intensity and the rainfall volume that fell within the 6 min the watershed s time of concentration before the sediment concentration was measured than with the runoff discharge the difference between the rainfall volume per unit time and the runoff discharge was primarily due to infiltration and transmission losses processes that reduce runoff volume but do not appear to affect the wash load concentration within the runoff infiltration and transmission losses are significant in this watershed and vary considerably in space and time but are generally described by an inverse relationship between the runoff coefficient and drainage area runoff coefficients vary amongst runoff events and are correlated to the peak rainfall intensity during each event results indicate that wash load concentrations are set by the sediment entrainment processes occurring on the hillslopes e g rainsplash hortonian overland flow and do not greatly fluctuate as water is routed through the watershed this suggests that wash load concentration may be better predicted by metrics of rainfall than flow discharge in certain environments using rainfall as a predictor of wash load could be useful for estimating sediment fluxes in semiarid regions where flow discharge is often difficult to monitor and sediment transport concentrations can be high i e 10 000 mg l 1

downstream patterns of suspended sediment transport in a high arctic river influenced by permafrost disturbance and recent climate change abstract spatially and temporally variable suspended sediment transport from upstream sources was investigated in the west river unofficial name at the cape bounty arctic watershed observatory cbawo on melville island nunavut 74 55 n 109 35 w a river with nearly a decade of hydrological and sediment transport research in the canadian arctic and subject to recent permafrost disturbances such as soil skin flows on slopes massive ground ice melt in the channel and substantial climate change during the 2012 season a survey was undertaken during the nival period to identify areas of the river where the flow was isolated from the channel bed by snow and where it progressively reached the bed during the nival period and throughout the rest of the season suspended sediment transport data were collected from a primary outlet station and six upstream locations to identify the sources and sinks of sediment in the various reaches of the west river an inferred sediment budget approach was used to identify the storage and release dynamics in each reach nival event scale hysteresis and seasonal diurnal hysteresis patterns for 2012 were primarily anticlockwise suggesting that sources of sediment were not readily available for transport during peak flows but became available as discharge waned analysis of diurnal hysteresis relationships for the years 2004 2012 excluding 2011 signals a shift in daily sediment discharge hysteresis from primarily clockwise to anticlockwise following an episode of permafrost disturbance and enhanced erosion in 2007 consistent sediment storage in the upper catchment from this disturbance is interpreted to have contributed to the shift to anticlockwise daily hysteresis results provide insights into the fluvial and geomorphological response to changes in sediment availability in arctic rivers and how these changes in turn affect sediment transport in these environments

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

alpine proglacial suspended sediment dynamics in warm and cool ablation seasons implications for global warming summary data on suspended sediment dynamics and loads obtained from the torrent du glacier noir ecrins massif se france during the unusually warm 2003 and cooler 2004 ablation seasons are used to indicate the likely future impacts of climate warming on suspended sediment transport processes in temperate alpine proglacial zones suspended sediment concentration ssc and discharge q were continuously monitored for 16 day periods during july 2003 and july 2004 ssc was monitored by automated pump sampling during diurnal events in each season and supplemented by a 10 min turbidity record q was monitored at a range of flows and a rating curve used to convert a 10 min water level record into q air temperature at was also logged at 10 min intervals throughout the study comparison of the 2003 and 2004 monitoring periods showed that daily mean at measured at the site was 1 2 c higher in 2003 mean q was 2 3 times higher and the suspended sediment load ssl was between 3 1 and 4 1 times greater in july 2003 than for the same period in the 2004 ablation season there is an increase in ssc during the 2004 observation period which is less apparent in 2003 most likely because higher ats and consequently higher q earlier in the 2003 melt season had removed available sediment before the study took place in july the rating curve method for estimating ssl produced a total load for the 16 day study period in 2003 which when corrected upwards to account for statistical bias was 10 314 743 t or 95 of the load estimated from the turbidity record for the same period in 2004 the corrected ssc q rating curve estimate was 2504 126 t while the estimate from the turbidity record was 743 112 t though a more sensitive turbidity sensor produced a higher estimate of 3474 302 t while the different ssl estimation methods in 2004 are not in perfect agreement the contrast between the two seasons is nevertheless very clear and is largely attributed to a mean monthly regional air temperature increase of 2 0 c over most of the 2003 ablation season the 2003 ssl record compared with 2004 can be used to gain an insight into the impact of higher air temperatures resulting from global warming on ssl such changes in ssls have important implications for sediment transfer from mountain to piedmont zones for stream ecology for downstream channel stability and flood risk and for the hydro electric industry

a genetic classification of carbonate platforms based on their basinal and tectonic settings in the cenozoic abstract this paper reassesses the usefulness of the morphological classification of carbonate platforms into rimmed shelves and ramps whilst the existing classifications have value in describing platform margin morphology at any one time the terms rimmed shelf and ramp are less successful at categorising the entire morphology and stratigraphy of carbonate platforms research on cenozoic carbonate platforms from a range of different tectono stratigraphic settings indicates that the basinal and tectonic setting of a platform can be used to erect a first order genetic classification of carbonate platforms the basinal and tectonic setting of carbonate platforms is shown to control their occurrence the overall 3 d platform morphology the large scale stratigraphic features and depositional sequences climate ocean chemistry and biological evolution control grain types facies and some elements of platform margins but not the larger scale features considered in this new classification from a review of well exposed outcropping and seismically imaged cenozoic platforms it is proposed that eight types of carbonate platform can currently be recognised and characterised based on their basinal and tectonic setting fault block salt diapir subsiding margin offshore bank volcanic pedestal thrust top delta top and foreland margin carbonate platforms these eight types are described using information from cenozoic platforms worldwide and the controls on their development are discussed many platform types e g subsiding margin offshore bank salt diapir thrust top and foreland margin are typical of particular classes of sedimentary basins others e g fault block volcanic pedestal and delta top are more widespread in their occurrence and occur in a range of basin types the value of this classification is that it is genetic rather than morphological the classification reflects the entire morphology and large scale stratigraphy of the platform and the controls on its development in addition the platform models can be used to understand the details of less well exposed or seismically imaged platforms so that they can be characterised and understood in terms of tectono sedimentary processes conversely the classification also provides valuable information on basin evolution as carbonate platforms house information on palaeoenvironments sea level change and are sensitive recorders of the tectonic environment

controls on slope to channel fine sediment connectivity in a largely ice free valley hoophorn stream southern alps new zealand there has been little work to date into the controls on slope to channel fine sediment connectivity in alpine environments largely ice free for most of the holocene characterization of these controls can be expected to result in better understanding of how landscapes relax from such perturbations as climate shock we monitored fine sediment mobilization on a slope segment hydrologically connected to a stream in the largely ice free 8 3 km2 hoophorn valley new zealand gerlach traps were installed in ephemeral slope channels to trap surficial material mobilized during rainfall events channel sediment flux was measured using turbidimeters above and below the connected slope and hysteresis patterns in discharge suspended sediment concentrations were used to determine sediment sources over the 96 day measurement period sediment mobilization from the slope segment was limited to rainfall events with increasingly larger particles trapped as event magnitude increased less than 1 of the mass of particles collected during these events was fine sediment during this period 714 t of suspended sediment was transported through the lower gauging station 60 of it during rainfall events channel sediment transfer patterns during these events were dominated by clockwise hysteresis interpreted as remobilization of nearby in channel sources further suggesting limited input of fine sediment from slopes in the lower valley strong counterclockwise hysteresis representing input of fine sediment from slope segments was restricted to the largest storm event jd2 2009 when surfaces in the upper basin were activated the results indicate that the slopes of the lower hoophorn catchment are no longer functioning as sources of fine sediment but rather as sources of coarse material with flux rates controlled by the intensity and duration of rainfall events although speculative these findings suggest a shift to a coarse sediment dominated slope to channel transfer system as the influence of pre holocene glacial erosion declines copyright 2011 john wiley sons ltd

catchment scale weathering fluxes in the southern alps new zealand abstract the dissolved and suspended sediment flux in a small headwater in the southern alps new zealand over a 16 month period showed that mass transferred as dissolved load 91 t km 2 a 1 is a significant flux relative to the suspended sediment flux 210 t km 2 a 1 export of dissolved load occurs mostly under baseflow with 268 t being transported over 10 discrete events relative to a total load of 1171 t over the experimental observation period which is equivalent to 23 of the ionic flux occurring during event flow storm events contribute 2420 t of suspended sediment accounting for 90 of the total suspended sediment flux the chemical weathering flux was 43 of the physical weathering flux and much higher than previous estimates of 1 9 for the southern alps such a high relative rate of chemical weathering is unlikely to be indicative of the full southern alps extent but suggests that in some regions of the eastern southern alps mass loss via chemical weathering may be a significant portion of overall flux during storm events temporal exhaustion of sediment occurred and inferred limited sediment source production rather than limited connectivity with the hillslope environment similar supply limitation is expressed in the ionic flux where rainfall events do not usually express hysteretic behaviour and event flow is dominated by a simple dilution recession

three decades of monitoring in the rio cordon instrumented basin sediment budget and temporal trend of sediment yield this paper investigates nearly 30 years of monitoring of sediment fluxes in an instrumented alpine basin rio cordon italy the collected bedload and suspended sediment transport data allows sediment dynamics to be analyzed at different time scales ranging from short single event to long term three decades the rio cordon monitoring station has been operating since 1986 continuously recording water discharge bedload and suspended load at the flood event scale a good relationship was found between peak discharges qpeak and sediment load bedload and suspended load the inter annual sediment yields were analyzed also assessing the contribution of the single floods to the total sediment budget the annual suspended load ranges from 10 to 2524 t yr 1 while the bedload varies from 0 to 1543 t yr 1 the higher annual yields were recorded in the years when large floods occurred highlighting that the sediment budget in the rio cordon is strongly controlled by the occurrence of high magnitude events investigation of the seasonal suspended load contribution demonstrated that from 1986 to 1993 most fine sediments were transported during the snowmelt summer seasons while autumn and snowmelt were the dominant seasons contributing to sediment yield in the periods 1994 2002 and 2003 2014 respectively the mean annual sediment yield from 1986 to 2014 is equal to 103 t km 2 yr 1 and overall bedload accounts for 21 of the total sediment yield the ratio between the sediment transport and the effective runoff of the events allowed the temporal trends of transport efficiency to be inferred highlighting the existence of periods characterized by different sediment availability in particular despite no significant changes in the hydrological variables i e rainfall nearly a decade 1994 2002 with high transport efficiency appears to have occurred after an exceptional event recurrence interval 100 years this event affected the sediment availability at the basin and channel bed scales and provided a legacy influencing the sediment dynamics in the basin over the long term by increasing the transport efficiency for approximately a decade this work benefits from the long lasting monitoring program undertaken in the rio cordon and is the product of long term data series the quasi unique dataset has provided detailed evidence of sediment dynamics over about three decades in a small alpine basin also enabling the effects triggered by an exceptional event to be analyzed

hyper concentrated flow response to aeolian and fluvial interactions from a desert watershed upstream of the yellow river abstract aeolian and fluvial interactions afis are critical earth surface processes in arid zones especially in desert watersheds the response of hyper concentrated flows to seasonal alternate afis shows very high rates of sediment transport and has important environmental and ecological consequences from local to global scales here we present the aeolian processes induced hyper concentrated ahc flows that occurred in the sudalaer desert watershed upstream of the yellow river which primarily transport non cohesive coarse aeolian sand 0 08 mm and show a peak suspended sediment concentration ssc of 1 1 to 1 4 106 mg l 3 our field study and theoretical analysis indicate that non cohesive coarse aeolian sand downstream in the channel can be entrained from the bed and can be suspended in the turbulent flow by the significant runoff generated upstream with a ssc 0 value of 0 5 106 mg l 3 severe aeolian processes can provide an abundant coarse sediment supply in the channel which once entrained can also trigger and promote the development of ahc flows we define for the first time the ratio of the weight percentage of coarse sediment to fine sediment c 0 08 mm c

short term discharge and suspended sediment fluctuations in the proglacial skeldal river north east greenland the summer discharge pattern of the skeldal river which drains a 560 km2 partly glacierized catchment in north east greenland is dominated by diurnal oscillations reflecting variations in the melt rate of snow and ice in the basin superimposed on this diurnal pattern are numerous short lived discharge fluctuations of irregular periodicity and magnitude the larger fluctuations are described and attributed to both rainfall events and periodic collapse of the glacier margin damming flow from beneath the skelbrae glacier other minor fluctuations are less readily explained but are associated with changes in the channelized and distributed reservoirs and possibly temporary blockage of subglacial conduits caused by ice melt with subsequent damming fluctuations in suspended sediment concentration ssc are normally associated with discharge fluctuations although examples of transient flushes were observed where marked increases in ssc occurred in the absence of corresponding discharge variations a strong relationship between the event discharge increase and event ssc increase for rainfall induced events was established but no such relationship existed for non rainfall induced events there is some evidence for an exhaustion effect in the ssc patterns both at the event time scale and as the month proceeds a mean suspended sediment load of 1765 0 26 t day 1 was estimated for the study period which would be equivalent to a suspended sediment yield of 732 4 t km 2 year 1 copyright 2001 john wiley sons ltd

temporal dynamics of suspended sediment transport in a glacierized andean basin abstract suspended sediment transport can affect water quality and aquatic ecosystems and its quantification is of the highest importance for river and watershed management suspended sediment concentration ssc and discharge were measured at two locations in the estero morales a chilean andean stream draining a small basin 27 km2 hosting glacierized areas of about 1 8 km2 approximately half of the suspended sediment yield 470 t year 1 km 2 was transported during the snowmelt period and half during glacier melting the hysteresis patterns between discharge and ssc were calculated for each daily hydrograph and were analysed to shed light on the location and activity of different sediment sources at the basin scale during snowmelt an unlimited supply of fine sediments is provided in the lower and middle part of the basin and hysteresis patterns tend to be clockwise as the peaks in ssc precede the peak of discharge in daily hydrographs instead during glacier melting the source of fine sediments is the proglacial area producing counterclockwise hysteresis it is suggested that the analysis of hysteretic patterns over time provides a simple concept for interpreting variability of location and activity of sediment sources at the basin scale

rainfall runoff and suspended sediment delivery relationships in a small agricultural watershed of the three gorges area china abstract following construction of the three gorges dam many farmers resettled in surrounding mountain areas and cultivated marginal lands which are mostly on steep slopes with soil of poor structure in general high soil loss rates occur during intense storms therefore soil erosion is a major environmental problem in the three gorges area tga of china understanding and quantifying sediment load is important for sustainable agriculture and the environment in this region this paper analyzes the relationships between rainfall runoff and sediment transport in the wangjiaqiao watershed strong seasonal and monthly variability in sediment load was found sediment was strongly transported during summer months a period when frequent flood events of high magnitude and intensity occurred analysis of the relationships between precipitation discharge and sediment transport at an individual event scale showed significant correlations between total precipitation peak discharge total water yield maximum 30 min rainfall intensity and sediment related variables stepwise multiple regression analysis revealed that rainfall amount is the major cause of runoff while events producing a large discharge in a short time play an important role in inducing severe soil erosion during 40 flood events three different types of hysteretic loops were observed clockwise 28 events 70 figure eight 5 events 12 5 and complex 7 events 17 5 the results of this study confirm the complex and heterogeneous nature of sediment response in the wangjiaqiao watershed

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

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

factors influencing storm generated suspended sediment concentrations and loads in four basins of contrasting land use humid tropical puerto rico abstract the significant characteristics controlling the variability in storm generated suspended sediment loads and concentrations were analyzed for four basins of differing land use forest pasture cropland and urbanizing in humid tropical puerto rico statistical analysis involved stepwise regression on factor scores the explanatory variables were attributes of flow hydrograph peaks and rainfall categorized into 5 flow periods 1 the current storm hydrograph 2 the flow and rainfall since the previous storm event 3 the previous storm event 4 2nd previous storm event and 5 the 3rd previous storm event the response variables storm generated sediment loads and concentrations were analyzed for three portions of the storm hydrograph 1 the entire storm 2 the rising limb and 3 the recessional limb hysteresis differences in sediment concentration between the rising and falling limb were also analyzed using these explanatory variables sediment availability in the study basins is related to land use and underlying geology the supply of sediment and its location in the watershed have a strong influence on how current and previous storm events and flow and rainfall between storm events affect sediment loads and concentrations in basins with limited sediment availability forest and pasture previous storm events supply sediment to the channel this in channel sediment becomes the source of sediment on the rising limb of the next event and clockwise hysteresis occurs in the cropland basin with high sediment availability sediment delivered to the channel during events becomes the source of sediment on the rising limb of the next event and clockwise hysteresis occurs in the urbanizing basin with high sediment availability counterclockwise hysteresis is prevalent as stormwater runoff dilutes suspended sediment concentrations on the rising limb and upland sediment arrives on the hydrograph recession in the urbanized basin previous storm events flush sediment from the system the statistical approaches presented here can be used to generate hypotheses on the location and delivery of watershed sediment sources which can improve the design of appropriate field studies

tectonic setting and stratigraphic architecture of an early cretaceous lacustrine carbonate platform sugar loaf high santos basin brazil abstract the sugar loaf high is an extensive basement structure within the santos basin offshore brazil in which all of the elements of the pre salt hydrocarbon play are present following a clastic dominated early synrift phase the later synrift and sag phases are characterized by an extensive non marine carbonate platform over the basement high the study area within this new 3d seismic dataset contains carbonates stratigraphically equivalent to the reservoirs within the lula and sapinhoa fields analysis of the 3d seismic data shows that the pre salt carbonates onlap the basement of the sugar loaf high and form aggradational geometries on a platform that has a proximal to distal width of about 100 km and an interpreted relief of some 900 m the carbonate platform has an aggradational and mounded basinward facing gullied margin with slope deposits progradational units are imaged on the platform top that may be either carbonate or clastic in composition the platform is preserved beneath evaporites that form the regional seal within the santos basin platforms of this size are previously unknown from lacustrine settings outside the pre salt stratigraphy of the santos and campos basins brazil

three dimensional stratigraphic sedimentological forward modeling of an aptian carbonate reservoir deposited during the sag stage in the santos basin brazil abstract stratigraphic sedimentological forward modeling is a useful technique to test the role of parameters that may act in the depositional processes of sedimentary rocks the technique was applied to the santos basin brazil using the software program dionisos to test possible depositional scenarios for an aptian section of a lacustrine carbonate platform developed during the late sag stage uppermost pre salt section of the basin different parameters were tested in a set of numerical simulations with the aim of reproducing the carbonate facies spatial distribution and the overall stratigraphic stacking pattern of the platform as observed in the available well data several models were simulated and four of them are discussed in this paper based on the available descriptive data from 10 wells model 3 is considered to produce the best fit to explain the development of the 100 m thick aptian carbonate platform occurrences of grainstones and stromatolites as proximal and intermediate facies respectively and the overall carbonate stacking pattern thus based on 3d stratigraphic sedimentological forward modeling the best set of environmental conditions able to explain the pattern of carbonate deposition observed in the study area are 1 a slow carbonate depositional rate 0 08 mm y over an interval of 2 4 my which is indicative of a larger microbial contribution and 2 lake level oscillations which were essentially induced by arid climatic conditions these results also enable new perspectives for the application of stratigraphic sedimentological forward modeling as a predictive tool for hydrocarbon exploration in carbonates and for the development of depositional models of other sag carbonate platform settings

presalt stratigraphy and depositional systems in the kwanza basin offshore angola the lower cretaceous presalt section in the kwanza basin contains an excellent petroleum system that includes synrift strata barremian overlain by a sag interval aptian and capped by the loeme salt the upper synrift is generally limestone with widespread mollusk packstones and grainstones coquinas deposited in a fresh to moderately saline alkaline lake the sag interval is characterized by carbonate platforms and silica rich isolated buildups formed in highly evaporated highly alkaline lakes shrubby dendritic microbially influenced boundstones and intraclast spherulite grainstones accumulated in shallow water on platform tops microbial cherts were deposited as organic buildups on large isolated structural highs basinward west of platforms and they apparently formed at low temperatures in very alkaline lake water shrubby boundstones and microbial cherts have vuggy pores that are primary and result in high permeability wackestones and packstones with calcitic grains mainly spherulites in dolomite or argillaceous dolomite were deposited in slightly deeper low energy sag environments in addition clays especially stevensite precipitated out of the silica rich highly alkaline lake waters during sag deposition calcite precipitated on the shallow lake floor with morphologies that ranged from spherulites to shrubs and included a continuum of intermediate forms spherulites probably precipitated just below the sediment water interface spherulites and shrubby calcites are commonly recrystallized spherulites floating in stevensite probably formed in deeper lacustrine environments organic rich mudstones were deposited in even deeper lacustrine environments in synrift and sag intervals and they are likely the source of most hydrocarbons in this system these interpretations are supported by seismic core petrographic and stable isotope data

bedload hysteresis in a glacier fed mountain river sediment transport during flood events often reveals hysteretic patterns because flow discharge can peak before counterclockwise hysteresis or after clockwise hysteresis the peak of bedload hysteresis in sediment transport has been used in the literature to infer the degree of sediment availability counterclockwise and clockwise hysteresis have been in fact interpreted as limited and unlimited sediment supply conditions respectively hysteresis has been mainly explored for the case of suspended sediment transport but it was rarely reported for bedload transport in mountain streams this work focuses on the temporal variability of bedload transport in an alpine catchment saldur basin 18 6 km2 italian alps where bedload transport was monitored by means of an acoustic pipe sensor which detects the acoustic vibrations induced by particles hitting a 0 5m long steel pipe runoff dynamics are dominated by snowmelt in late spring early summer mostly by glacier melt in late summer early autumn and by a combination of the snow and glacier melt in mid summer the results indicate that hysteretic patterns during daily discharge fluctuations are predominantly clockwise during the snowmelt period likely due to the ready availability of unpacked sediments within the channel or through bank erosion in the lower part of the basin on the contrary counterclockwise hysteresis tend to be more frequent during late glacier melting period possibly due to the time lag needed for sediment provided by the glacial and peri glacial area to be transported to the monitoring section however intense rainfall events occurring during the glacier melt period generated predominantly clockwise hysteresis thus indicating the activation of different sediment sources these results indicate that runoff generation processes play a crucial role on sediment supply and temporal availability in mountain streams

near channel versus watershed controls on sediment rating curves predicting riverine suspended sediment flux is a fundamental problem in geomorphology with important implications for water quality land and water resource management and aquatic ecosystem health to advance understanding we evaluated environmental and landscape factors that influence sediment rating curves srcs we generated srcs with recent total suspended solids tsss and discharge data from 45 gages on 36 rivers throughout the state of minnesota usa watersheds range from 32 to 14 600 km2 and represent distinct settings regarding topography land cover and geologic history rivers exhibited three distinct src shapes simple power functions threshold power functions and peaked or negative slope functions we computed src exponents and coefficients describing the steepness of the relation and the tss concentration at median flows respectively in addition to quantifying watershed topography climate hydrology geology soil type and land cover we used lidar topography to characterize the near channel environment upstream of gages we used random forest models to analyze relations between src parameters and attributes of the watershed and the near channel environment the models correctly classify 78 of src shapes and explain 37 60 of variance in src parameters we find that src steepness exponent is strongly related to near channel morphological characteristics including near channel relief channel gradient and presence of lakes along the local channel network but not to land use in contrast land use influences tss concentrations at moderate and low flow these findings suggest that the near channel environment controls changes in tss as flows increase whereas land use drives median and low flow tss conditions

experimental evidence for the effect of hydrographs on sediment pulse dynamics in gravel bedded rivers 1 gravel augmentation is a river restoration technique applied to channels downstream of dams where size selective transport and lack of gravel resupply have created armored relatively immobile channel beds augmentation sediment pulses rely on flow releases to move the material downstream and create conditions conducive to salmon spawning and rearing yet how sediment pulses respond to flow releases is often unknown here we explore how three types of dam releases constant flow small hydrograph and large hydrograph impact sediment transport and pulse behavior translation and dispersion in a channel with forced bar pool morphology we use the term sediment pulse generically to refer to the sediment introduced to the channel the zone of pronounced bed material transport that it causes and the sediment wave that may form in the channel from the additional sediment supply which can include input sediment and bed material in our experiments we held the volume of water released constant which is equivalent to holding the cost of purchasing a water volume constant in a stream restoration project the sediment pulses had the same grain size as the bed material in the channel we found that a constant flow 60 greater than the discharge required to initiate sediment motion caused a mixture of translation and dispersion of the sediment pulse a broad crested hydrograph with a peak flow 2 5 times the discharge required for entrainment caused pulse dispersion while a more peaked hydrograph 3 times the entrainment threshold discharge caused pulse dispersion with some translation the hydrographs produced a well defined clockwise hysteresis effecting sediment transport as is often observed for fine sediment transport and transportlimited gravel bed rivers the results imply a rational basis for design of water releases associated with gravel augmentation that is directly linked to the desired sediment behavior

seasonal controls on sediment delivery in a small coastal plain watershed north carolina usa field measurements of drainage ditch sedimentation and suspended sediment transport were used to construct a simple sediment budget and relate seasonal variations in vegetation and the hydrological characteristics of storms to sediment dynamics in a small agricultural watershed in north carolina results indicate that seasonal variations in crop coverage and vegetation in drainage ditches influence sediment delivery following the harvesting of crops and mowing of drainage ditches in late autumn conditions are favorable to soil erosion and sediment transport through early spring storms need not be very intense or produce large rainfall totals to transport significant sediment loads the maturation of field crops and ditch vegetation in spring produces conditions less conducive to both soil erosion and sediment transport intense summer thunderstorms however are capable of mobilizing and transporting significant amounts of sediment the computed sediment yield of 0 1 mg ha yr probably represents a low estimate that nevertheless is an order of magnitude less than measured ditch storage and more than two orders of magnitude less than regional estimates of soil loss on coastal plain croplands the results show that headwater ditches may be decoupled from slopes so that much of the eroded soil is stored within small watersheds rather than being transported out of the basin

geometric attributes for seismic stratigraphic interpretation the application of sequence stratigraphy to seismic interpretation has proven to be fundamentally important in basin analysis it provides a framework for understanding strat igraphic evolution and is a key element in predicting the spatial distribution of reservoir seal and source rocks traditional methods of seismic se quence stratigraphy make use of observations such as stacking patterns seismic character of facies and their distribution to develop subsurface models we present a set of seismically derived geometric attributes that enhance and characterize these observations allowing a sequence stratigraphic framework to be developed in the earliest stages of interpretation