sediment budget analysis of slope channel coupling and in channel sediment storage in an upland catchment southeastern australia abstract slope channel coupling and in channel sediment storage can be important factors that influence sediment delivery through catchments sediment budgets offer an appropriate means to assess the role of these factors by quantifying the various components in the catchment sediment transfer system in this study a fine

stress strain and strength characteristics of silt clay transition soils abstractthe influence of nonplastic silt content on the stress strain volume change and strength characteristics of anisotropic silt clay transition soils is investigated a series of one dimensional compression tests isotropic compression tests and undrained and drained triaxial tests on three soils of similar base clay but different nonplastic silt contents are performed on cross anisotropic specimens prepared from consolidation of slurries tests with major loading directions both parallel and perpendicular to the specimens axis of deposition are performed it is observed that the tested silt clay soils are less compressible with increasing silt content during one dimensional and isotropic compression tests during drained and undrained triaxial tests the normally consolidated soils at the same consolidation stress show larger values of stiffness and drained and undrained shear strengths with increasing silt content the silt clay soils also show larger pore pressure changes during undrained tria

sediment sources and siltation in mountain reservoirs a case study from the central spanish pyrenees abstract based on a 137 cs derived chronology we reconstruct the depositional history of the barasona reservoir in the esera isabena basin central pyrenees spain most of the sediments were delivered to the barasona reservoir during flood events comparative mineralogical studies of the esera and isabena river channels and the barasona reservoir sediments help to identify sediment sources and areas of high sediment yield risk and to establish erosion and sediment transport processes in the watershed changes in the mineralogical composition of the sediments can be used to discriminate the relative contribution of the esera and isabena rivers during flood periods three main periods in the siltation history of the barasona reservoir were distinguished 1 from dam construction 1932 to the early 1950s the reservoir was flushed every year using the lower gates and average sediment accumulation was very low 1 5 cm yr 2 during the 1950s and 1960s the sedimentation rate increased and reached the highest values 15 cm yr 24 6 cm yr and 18 2 cm yr in the esera river mouth the northern and the southern areas of the reservoir respectively both changes in the exploitation regime no annual flushes and climate variability increased flood frequency and river inflow caused this increase in sediment delivery and accumulation 3 the third period was initiated by the enlargement of the dam in 1972 the new sedimentary dynamics in the reservoir caused a general decrease in the sedimentation rate 11 6 cm yr in the southern areas 10 cm yr in the esera mouth that was especially noticeable in the northern areas where the accumulation rate was reduced to 3 7 cm yr an increase in channel erosion processes during this period contributed to the transport of sediments to the inner areas of the reservoir

rainfall runoff and sediment transport relations in a mesoscale mountainous catchment the river isabena ebro basin this paper examines the relations between rainfall runoff and suspended sediment transport in the isabena basin during a quasi average hydrological year the isabena is a mesoscale river basin that drains a mountainous area comprising patches of highly erodible materials badlands the paper includes an analysis of the different hydrological and sedimentary responses of the catchment to a similar rainfall thirty four floods were studied with a very variable response observed runoff coefficients ranged from 0 32 to 33 the sedimentary response was also highly variable with maximum suspended sediment concentrations ssc oscillating between 0 1 and 90 g l 1 and flood sediment loads varying from 27 to 54 000 t per hydrological event most sediment load was concentrated in spring when competent floods occur frequently pearson correlation matrix and backward stepwise multiple regression indicate that the hydrological response of the catchment is strongly correlated with total precipitation event duration and rainfall of the previous days very low correlation was observed with rainfall intensity the relation between rainfall and sediment transport followed the same trend sediment variables e g total load and ssc were significantly correlated with variables such as total rainfall and rainfall over the previous days although the significance level was lower in comparison with the runoff related variables there was again no correlation between sediment variables and rainfall intensity on going research in the area suggests that apart from rainfall factors such as sediment availability in the badlands and accumulation of sediment in the channels influences the river s sedimentary response the non linear hydrosedimentary response is reflected in the wide range of runoff coefficients and sediment loads that have been observed in response to similar amounts of precipitation

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

landslide susceptibility revealed by lidar imagery and historical records seattle washington abstract light detection and ranging lidar data were used to visually map landslides headscarps and denuded slopes in seattle washington four times more landslides were mapped than by previous efforts that used aerial photographs the mapped landforms landslides headscarps and denuded slopes were created by many individual landslides the spatial distribution of mapped landforms and 1308 historical landslides show that historical landslide activity has been concentrated on the mapped landforms and that most of the landslide activity that created the landforms was prehistoric thus the spatial densities of historical landslides on the landforms provide approximations of the landforms relative susceptibilities to future landsliding historical landslide characteristics appear to be closely related to landform type so relative susceptibilities were determined for landslides with various characteristics no strong relations were identified between stratigraphy and landslide occurrence however landslide characteristics and slope morphology appear to be related to stratigraphic conditions human activity is responsible for causing about 80 of historical seattle landslides the distribution of mapped landforms and human caused landslides suggests the probable characteristics of future human caused landslides on each of the landforms the distribution of mapped landforms and historical landslides suggests that erosion of slope toes by surface water has been a necessary condition for causing seattle landslides human activity has largely arrested this erosion which implies that landslide activity will decrease with time as hillsides naturally stabilize however evaluation of glacial age analogs of areas of recent slope toe erosion suggests that landslide activity in seattle will continue for the foreseeable future

runoff and soil moisture as driving factors in suspended sediment transport of a small mid mountain mediterranean catchment abstract soil moisture conditions play a key role in runoff and sediment load dynamics in river catchments of contrasting ecosystems however the highly marked seasonality of mediterranean climate affects hydrological processes and sediment transport strongly as evapotranspiration determines a succession of wet transition and dry periods throughout a hydrological year this study examines results of soil moisture water and sediment fluxes during five hydrological years in a representative small mid mountain mediterranean catchment it aims to assess the sediment load contribution and its variability at different temporal scales precipitation runoff and suspended sediment load were calculated at annual seasonal and event scales to assess inter and intra annual variability a database with 45 events was used to identify the main controlling factors over sediment load thought bivariate relationships and an analysis of soil moisture discharge and discharge suspended sediment concentration hysteresis at the annual scale lithology land use and soil conservation structures characteristic of the catchment caused low values of sediment yield although inter annual rates varied by up to three orders of magnitude 0 08 to 11 86 t km 2 y 1 seasonal analysis of accumulated sediment load showed that 80 was generated during the autumn and winter seasons at the event scale streamflow and soil moisture were the controlling factors for the largest sediment load contributions the highest frequency of clockwise discharge suspended sediment concentration hysteresis revealed that most of the sediment was generated from nearby sources although the largest sediment loads were contributed under wet antecedent conditions as depicted by the soil moisture discharge hysteresis assessment

quantifying sediment connectivity in an actively eroding gully complex waipaoa catchment new zealand abstract using a combination of airborne lidar 2005 and terrestrial laser scanning 2007 2008 2010 2011 sediment delivery processes and sediment connectivity in an 20 ha gully complex which significantly contributes to the waipaoa sediment cascade are quantified over a 6 year period the acquisition of terrain data from high resolution surveys of the whole gully fan system provides new insights into slope processes and slope channel linkages operating in the complex raw terrain data from the airborne and ground based laser scans were converted into raster dems with a vertical accuracy between surveys of 3 of sediment annually with a standard deviation of 20 806 m 3 the volumes of debris eroded from those areas dominated by surface erosion processes were higher than in areas dominated by landslide processes over the six year study period sediment delivery from the source zones to the fan was a factor of 1 4 times larger than the volume of debris exported from the fan into te weraroa stream the average annual volume of sediment exported to te weraroa stream varies widely from 23 195 to 102 796 m 3 fluctuations in the volume of stored sediment within the fan rather than external forcing by rainstorms or earthquakes account for this annual variation no large rainfall events occurred during the monitoring period therefore sediment volumes and transfer processes captured by this study are representative of the background conditions that operate in this geomorphic system

fingerprinting changes of source apportionments from mixed land uses in stream sediments before and after an exceptional rainstorm event abstract the loss of fertile topsoil is one of the principal soil degradation problems in mountain agroecosystems worldwide soil erosion rates reach their maximum during exceptional storm events that remove soil particles especially from unprotected topsoil in mediterranean mountainous environments several centuries of non irrigated agriculture and the subsequent removal of natural vegetation for developing agriculture has increased the surface area prone to erosion in addition the irregularity in exceptional precipitation events results in a great loss of fertile soil the subsequent siltation of reservoirs and a decrease in water quality to analyse the soil response to exceptional events 161 source samples were collected in a 23 km2 catchment that was mostly cultivated at the beginning of the last century source samples were distributed over the five main land use land covers such as agricultural land pine afforestation open forest bare soil and channel bank areas furthermore 20 channel bed sediment samples were collected along the main streams before and after the exceptional storm event to document changes in the sediments in addition floodplain sediments were collected to provide a close replication of sediments deposited during regular storm events source apportionments were calculated using the fingerpro unmixing model in the pre event regular events and post event scenarios the unmixing outputs displayed a large variation of source apportionments from the upper part to the lower part of the catchment and from pre to post event sediments after the event a decrease of 70 of the clay fraction and its associated elements such as fe al k ba sr rb pb zn v 137cs 40k 232th and soc along with a rise in contents of elements associated with the coarse fraction si nb zr ti p and 226ra was recorded in the channel bed sediments at the catchment outlet the pre event sediment showed substantial contributions from bare soil 29 and from agriculture and channel banks which both reached 35 while the channel bank was the main source along the catchment ranging between 44 and 71 the low contribution from soil under natural covers with a mean value

regional scale modeling of hillslope sediment delivery a case study in the barasona reservoir watershed spain using watem sedem summary soil erosion and sediment delivery to streams are important environmental problems and major concerns in sustainable development in recent years several tools have been proposed for assessing the delivery of sediment from hillslopes to stream networks but there are still few examples of their application to large basins and studies include a discussion of calibration and validation issues in this study a spatially distributed soil erosion and sediment delivery model watem sedem was applied to the watershed of the barasona reservoir 1504 km 2 central spanish pyrenees which is drained by the esera and isabena rivers model calibration and validation was based on the depositional history of the barasona reservoir and suspended sediment records over 3 years may 2005 may 2008 at the outlet of the isabena river despite interannual differences in precipitation and runoff it was possible to establish an optimum value 7 23 for the ktc parameter this enabled estimation of the long term average annual sediment yield to the reservoir as well as the relative contribution of each river large spatial variability in hillslope sediment delivery was found and the major sediment sources were in the lower part of the watershed agricultural fields and in the badlands developed on eocene marls in the middle part of the watershed pyrenean inner ranges the relative importance of sediment source areas was assessed in relation to land use and the relationship between the sediment delivery ratio and the catchment area was studied as a function of the geomorphological units for the moment watem sedem remains mainly as a researcher s tool until either the problem of the scarcity of soil erosion data or the need for calibration of the transport parameters will be solved

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

hydraulics and basin morphometry of the largest flash floods in the conterminous united states abstract the maximum rainfall runoff floods measured by indirect methods in small basins 0 39 370 km2 in the conterminous united states are examined this analysis identified twelve floods that were the largest ever measured these floods all occurred in semiarid to arid areas for eleven of the twelve largest rainfall runoff floods measured in small basins by the slope area method values of hydraulic depth hydraulic radius width depth ratio n value mean velocity velocity head coefficient froude number water surface energy and channel slopes shear stress and unit stream power are tabulated estimated composite n values weighted by subsection conveyance range from 0 028 to 0 048 with a mean of 0 038 mean velocities ranged from 3 47 to 9 97 m s 1 froude numbers ranged from 0 81 to 2 49 with 9 of 12 floods having values greater than 1 00 water surface energy and channel slopes vary considerably for each flood energy slope always was less than water surface slope by values of 1 104 channel slope was greater than energy slope in eight floods shear stresses ranged between 61 and 855 n m 2 and unit stream power from 212 to 8131 w m 1 floods in these small basins produced shear stresses and unit stream powers several hundred times greater than floods in large rivers floods on other small streams with smaller unit discharges produced greater shear stresses and stream powers this indicates that the force of a flood is controlled by the depth slope product not absolute discharge in the twelve watersheds studied basin relief ranged from 165 to 1280 m elongation ratios ranged from 0 55 to 0 80 the number of first order streams basin magnitude ranged from 10 to 4297 drainage density ranged from 4 1 to 10 9 km km 2 basin slope ranged from 0 0043 to 0 2486 relief ratio ranged from 0 0097 to 0 34 ruggedness number ranged from 0 69 to 7 17 and first order channel frequency ranged from 5 1 to 38 6 km 2 elongation ratios were larger and drainage density and first order channel frequency lower than other small flash flood prone basins in the united states these twelve basins have neither the most favorable morphometric characteristics which contribute to flash flood peaks nor did the storms causing these flash floods have the greatest short duration intensities maximum flood peaks originate from an optimal combination of basin morphology and physiography and storm intensity

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

the undrained behaviour of clayey sands in triaxial compression and extension the paper describes an experimental investigation of the stress strain behaviour of anisotropically consolidated clayey sands carried out using instrumented and computer controlled triaxial cells the specimens were prepared by sedimenting ham river sand into a kaolin suspension for a given granular void ratio as the clay content of the sedi mented clayey sands increases from 4 6 to 10 the undrained brittleness and strains to phase transformation also increase when the specimens are sheared in compression when sheared in extension liquefaction takes place for clay contents up to 7 5 increases in granular void ratio give rise to increased brittleness and potential to liquefaction the effects of overconsolidation on strength and stiffness characteristics have been examined the effective stress paths for undrained shear of the normally consolidated soil form a boundary for the effective stress paths for the lightly overconsolidated soil l article decrit une etude experimentale effectuee a l aid

suspended sediment transport in a highly erodible catchment the river isabena southern pyrenees abstract understanding and quantifying sediment load is important in catchments draining highly erodible materials that eventually contribute to siltation of downstream reservoirs within this context the suspended sediment transport and its temporal dynamics have been studied in the river isabena 445 km 2 south central pyrenees ebro basin by means of direct sampling and turbidity recording during a 3 year dry period the average flood suspended sediment concentration was 8 g l 1 with maximum instantaneous values above 350 g l 1 the high scatter between discharge and suspended sediment concentrations up to five orders of magnitude has not permitted the use of rating curve methods to estimate the total load interpolation techniques yielded a mean annual sediment load of 184 253 t y 1 for the study period with a specific yield of 414 t km 2 y 1 this value resembles those reported for small torrents in nearby mountainous environments and is the result of the high connectivity between the badland source areas and stream courses a fact that maximises sediment conveyance through the catchment floods dominated the sediment transport and yield however sediment transport was more constant through time than that observed in mediterranean counterparts this can be attributed to the role of base flows that entrain fine sediment temporarily stored in the channel and force the river to carry high sediment concentrations i e generally in the order of 0 5 g l 1 even under minimum flow conditions

sediment transport from continuous monitoring in a perennial mediterranean stream vericat d batalla r j 2010 sediment transport from continuous monitoring in a perennial mediterranean stream catena 82 2 77 86 sponsorship research project sediment export from large semi arid catchments measurements and modelling sesam funded by the deutsche forschungsgemeinschaft dgf

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

an evaluation of direct simple shear tests on clay normally consolidated samples of kaolin have been tested in two direct simple shear apparatuses the first apparatus is specially instrumented with load cells in the horizontal boundaries to investigate the uniformity of the stresses acting on the samples the internal deformations and strains are determined using radiographic techniques the radial stress is determined from membranes reinforced with resistance wire the second apparatus is a standard commercially available device supplied by geonor the stresses and strains are shown to be uniform in the central region of the sample away from the vertical boundaries until failure values of the stress and strain variables determined from the central region are representative of a uniform simple shear deformation in plane strain in all tests the samples fail by developing approximately horizontal ruptures values of the shear modulus and shear strength estimated from the average stresses in the geonor apparatus underestimate by approximately 10 the

sediment transport in a large impounded river the lower ebro ne iberian peninsula abstract the sediment transport of the highly regulated lower ebro river is estimated on the basis of a measuring programme carried out between 2002 and 2004 total sediment transport including both suspended load and bedload was measured upstream and downstream from the mequinenza and riba roja reservoirs with special attention to the transport during floods annual total load upstream from the dams is estimated at around 1 64 106 t of which at least 99 is transported in suspension annual total load downstream from the dams is estimated at around 0 45 106 t of which 60 is transported in suspension and the remaining 40 as bedload mean d50 bl in the range of 32 mm total load represents 3 of what was transported at the beginning of the 20th century in the delta plain sediment yield is three to four times lower below the dams a fact that is caused by the trapping of sediment within the reservoirs around 90 in the case of suspended sediment and 100 in the case of bedload as a consequence sediment that is transported downstream from the dams is all entrained from the riverbed and eroded from the banks the sediment deficit causes a mean riverbed incision of 30 mm per year as estimated from bedload measurements and by means of scour chains and painted pebbles located between the lowermost dam and the measuring section 28 km downstream since floods have been reduced on average by 25 but sediment supply from upstream has been reduced to almost nothing the river channel of the lower ebro river will continue exporting sediment both during floods 2000 m3 s mostly bedload and frequent high flows 1000 m3 s to 2000 m3 s making the incision progressive unless restoration steps are taken

erosion in mediterranean landscapes changes and future challenges abstract intense erosion processes are widespread in the mediterranean region and include sheet wash erosion rilling gullying shallow landsliding and the development of large and active badlands in both subhumid and semi arid areas this review analyses the main environmental and human features related to soil erosion processes and the main factors that explain the extreme variability of factors influencing soil erosion particularly recent land use changes the importance of erosion in the mediterranean is related to the long history of human activity in a region characterized by low levels of annual precipitation the occurrence of intense rainstorms and long lasting droughts high evapotranspiration the presence of steep slopes and the occurrence of recent tectonic activity together with the recurrent use of fire overgrazing and farming these factors have resulted in a complex landscape in which intensification and abandonment wealth and poverty can co exist the changing conditions of national and international markets and the evolution of population pressure are now the main drivers explaining land use changes including farmland abandonment in mountain areas the expansion of some subsidized crops to marginal lands and the development of new terraces affected by landslides and intense soil erosion during extreme rainstorm events the occurrence of human related forest fires affecting thousands of hectares each year is a significant problem in both the northern and southern areas of the mediterranean basin here we highlight the rise of new scientific challenges in controlling the negative consequences of soil erosion in the mediterranean region 1 to reduce the effects and extent of forest fires and restructure the spatial organization of abandoned landscapes 2 to provide guidance for making the eu agricultural policy more adapted to the complexity and fragility of mediterranean environments 3 to develop field methods and models to improve the identification of runoff and sediment contributing areas 4 to contribute to the conservation of landscapes i e bench terraced fields having high cultural and productivity values 5 to improve knowledge of the hydrological and geomorphological functioning of badlands with the aim of reducing sediment yield and accessibility 6 to better understand the effect of climate change on soil erosion in the mediterranean region and 7 to improve quantitative information on long term soil erosion

atmospheric and hydrological boundary conditions for slushflow initiation due to snowmelt slush flows of a large variety of magnitudes were observed during three field campaigns to liefdefjorden northwestern spitsbergen and one campaign to karke vagge northern sweden in the latter campaign the release and movement of a slush torrent was documented on video and in photographs meteorological and snow hydrological measurements carried out during these campaigns were analysed with respect to slushflow initiation due to snow melt since slushflows are quite common in polar and sub polar drainage basins although they are not restricted to these regions specific atmospheric and hydrological boundary condittons must be fulfilled for slushflow initiation due to snowmelt radiative fluxes air temperatures and wind velocities are the most important atmospheric variables while snow depth depth of the water saturated layer hydraulic conductivity and snow structure are the primary snow variables of interest it has been shown that slushflows can be released due to energy input in the snow cover by net radiation and sensible heat within the ordinary range of the high latitudinal snow melt period slush torrent initiation is intensified by a superpositton of both energy fluxes infiltration losses were not significant even when permafrost was not present crucial for slushflow initiation due to snowmelt is the timing of energy input and meltwater flow through the snowpack

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

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

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

the application of predictive modeling techniques to landslides induced by earthquakes the case study of the 26 september 1997 umbria marche earthquake italy abstract during september and october 1997 an earthquake sequence of moderate magnitude struck the umbria and marche regions central italy as a consequence of the most severe shocks several landslides were triggered on bedrock calcareous debris and sandy clay deposits the landslide inventory collected in the field and by aerial photo interpretation provided an opportunity to test the accuracy of existing predictive relations for landslide hazard zoning and to formulate new ones shallow soil slides and debris slides were selected to verify the prediction performance of the methods which are based on a simplified model geotechnique 15 1965 139 that calculate landslide displacements during cyclic seismic loading rock falls were modeled using a different approach to produce an empirical predictive rule for determining the probability of detachment of blocks when landslides occur along pre existing or newly formed failure surfaces the arias intensity and destructiveness potential are the strong ground motion parameters that best relate to displacements the predictive relation proposed for rock falls evaluates the probability of occurrence as a function of the slope angle and the peak ground acceleration pga

effects of gravel content on shear resistance of gravelly soils abstract shallow landslides in colluvium which generally consists of wide particle gradation in a loose state occur in steep slope terrains to perform stability analyses shear strength parameters that represent soil constituents in situ stress state and shearing mode are needed this experimental study investigates the effects of gravel content on the shearing characteristics of gravelly soils based on the intergrain state concept a series of drained simple shear tests was performed on reconstituted specimens of gap and well graded sands with various gravel content levels the results reveal that 1 the shear strength of gravelly soils depends on the packing condition of dominant particles with the intergrain granular void ratio being a more representative parameter for the soil packing condition than the global void ratio 2 the drained shear strength of loose gravelly sand is dominated by sand matrix properties with the inclusion of gravel content reducing the strength by no more than 20 compared to that of pure sand 3 the strength parameters of sand like gravelly soils can be estimated from the sand matrix with proper reduction

temporal variability of suspended sediment sources in an alpine catchment combining river rainfall monitoring and sediment fingerprinting influence of the rainfall regime on erosion and transfer of suspended sediment in a 905 km 2 mountainous catchment of the southern french alps was investigated by combining sediment monitoring rainfall data and sediment fingerprinting based on geochemistry and radionuclide concentrations suspended sediment yields were monitored between october 2007 and december 2009 in four subcatchments 22 713 km 2 automatic sediment sampling was triggered during floods to trace the sediment origin in the catchment sediment exports at the river catchment outlet 330 pm 100 t km 2 yr 1 were mainly driven 80 by widespread rainfall events long duration low intensities in contrast heavy local and short duration storms generated high peak discharges and suspended sediment concentrations in small upstream torrents however these upstream floods had generally not the capacity to transfer the sediment down to the catchment outlet and the bulk of this fine sediment deposited along downstream sections of the river this study also confirmed the important contribution of black marls up to 70 to sediment transported in rivers although this substrate only occupies c 10 of the total catchment surface sediment exports generated by local convective storms varied significantly at both intra and inter flood scales because of spatial heterogeneity of rainfall however black marls marly limestones contribution remained systematically high in contrast widespread flood events that generate the bulk of annual sediment supply at the outlet were characterized by a more stable lithologic composition and by a larger contribution of limestones marls quaternary deposits and conglomerates which corroborates the results of a previous sediment fingerprinting study conducted on riverbed sediment

field observations on hyperconcentrated flows in mountain torrents field observations on hydraulics and sediment dynamics during extreme floods in two mountain torrents show the influence of man made constructions such as bridges and check dams in addition to the sediment supplied naturally by the basin and the channel network on the formation of hyperconcentrated flows in the pyrenean aras basin hyperconcentrated flow occurred after collapse of a bridge which in turn mobilized large volumes of sediment from the stream channel and subsequently destroyed a series of check dams boulders up to several metres in size were transported in a mixture of sand and fine material a minimum of 100000 tonnes of sediment were deposited on the alluvial fan during the event prior to bridge destruction mean bedload transport rates had reached 0 4t m 1 s 1 upstream in the alpine lainbach basin the flood was characterized by transportation of large amounts of slope material including debris flows along its main tributary an intensive hyperconcentrated flow occurred during the rising stage whereas in the main valley smaller flows occurred after failure of check dams the depth of coarse material deposited reached 80 cm the effectiveness of the aras and lainbach floods was attained due to exceptional rates of energy expediture flood power ranged from 20000 w m 2 to 40000 w m 2 on average copyright 1999 john wiley sons ltd

slope channel coupling in steepland terrain a field based conceptual model from the tarndale gully and fan waipaoa catchment new zealand abstract connectivity between an actively eroding gully complex and upper waipaoa catchment via a steep 1 km long alluvial fan is assessed using digital elevation models dems of the tarndale fan derived from 10 high resolution gps surveys between 2004 and 2008 repeat dem analysis provides a means of assessing transfer of sediment supplied from the tarndale gully through the fan to the te weraroa stream and thus inferring connectivity between these landscape components from which a conceptual coupling model is derived analysis indicates the operation of two critical junction switches at the i gully fan and ii fan stream nexus which contribute to considerable complexity in patterns of erosion and deposition on the fan as it responds to sediment supply or starvation from the tarndale gully and evacuation to the te weraroa stream described in fuller and marden 2010 the fan does not respond as a coherent unit each of six fan feeder tributaries behaves independently according to sediment supplied from six discrete source areas within the gully complex this reflects sediment production within specific activity zones of tarndale gully mass movements triggered by single rainstorm events and or wet periods contingent upon sediment availability and intrinsic slope mechanics frequently deliver sediment to the upper fan tributaries this enhanced gully fan coupling during storms or wetter periods promotes rapid fan aggradation with each feeder tributary responding to its discrete source zone infilling may propagate down fan in response to upper fan incision once the gully fan switch deactivates transferring sediment as far as the te weraroa stream coupling the fan with the stream system floods generated in the te weraroa stream may also activate the junction switch at the fan stream nexus by trimming the lower fan prompting up fan incision via head cutting in response to changed local base level slope channel coupling in this environment is a function of a range of slope and channel processes responding to discrete storms and intrinsic gully dynamics the high rates of geomorphic activity in this environment mean the tarndale system provides a natural laboratory in which to assess key slope channel coupling processes beyond the plot or discrete event scale

variation in flow and suspended sediment transport in a montane river affected by hydropeaking and instream mining abstract the temporal and spatial variability of water and sediment loads of rivers is controlled by a suite of factors whose individual effects are often difficult to disentangle while land use changes and localised human activities such as instream mining and hydropeaking alter water and sediment transfer tributaries naturally contribute to discharge and sediment load of mainstem rivers and so may help compensate upstream anthropogenic factors the work presented here aimed to assess water and the sediment transfer in a river reach affected by gravel extraction and hydropeaking set against a backdrop of changes to the supply of water and sediment from tributaries discharge and suspended sediment transport were monitored during two average hydrological years at three cross sections along a 10 km reach of the upper river cinca in the southern pyrenees water and sediment loads differed substantially between the reaches the upper reach showed a largely torrential discharge regime controlled mainly by floods and had high but variable water and sediment loads the middle reach was influenced markedly by hydropeaking and tributary inflows which increased its annual water yield four fold suspended sediment load in this reach increased by only 25 compared to upstream indicating that dilution predominated in the lowermost section while discharge remained largely unaltered sediment load increased appreciably as a result of changes to sediment availability from instream mining and inputs from tributaries at the reach scale snowmelt and summer and autumn thunderstorms were responsible for most of the water yield while flood flows determined the magnitude and transport of the sediment load the study highlights that a combination of natural and human factors control the spatial and temporal transfer of water and sediment in river channels and that depending on their geographic location and effect size can result in marked variability even over short downstream distances

the sediment budget of a highly dynamic mesoscale catchment the river isabena the paper presents the sediment budget of the isabena basin a highly dynamic 445 km2 catchment located in the central pyrenees that is patched by highly erodible areas i e badlands the budget for the period 2007 2009 is constructed following a methodology that allows the interpolation of intermittent measurements of suspended sediment concentrations and enables a subsequent calculation of sediment loads data allow specification of the contribution of each subbasin to the water and sediment yield in the catchment outlet mean annual sediment load was 235 000 t y 1 specific sediment yield reached 2000 t km 2 y 1 a value that indicates very high sedimentary activity especially in the case of villacarli and lascuarre subcatchments were most badlands are located the specific sediment yield obtained for the entire isabena is 527 t km 2 y 1 a high value for such a mesoscale basin results show that a small part of the area i e 1 controls most of the catchment s gross sediment contribution sediment delivery ratio ratio between sediment input from primary sources and basin export has been estimated at around 90 while in channel storage represents the 5 of the annual load on average the high connectivity between sediment sources i e badlands and transfer paths i e streamcourses exacerbates the influence of the local sediment production on the catchment s sediment yield a quite unusual fact for a basin of this scale

temporal variation of suspended sediment transport in the koga catchment north western ethiopia and environmental implications event sediment transport and yield were studied for 45 events in the upstream part of the 260 km2 agricultural koga catchment that drains to an irrigation reservoir discharge and turbidity data were collected over a period of more than a year accompanied by grab sampling turbidity was very well correlated with the sediment concentrations from the samples r 0 99 which allowed us to estimate the temporal patterns of sediment concentrations within events the hysteresis patterns between discharge and sediment concentrations were analysed to provide insight into the different sediment sources anticlockwise patterns are the dominant hysteresis patterns in the area suggesting smaller contributions of suspended sediment from the river channels than from the hillslopes and agricultural areas complicated types of hysteresis patterns were mostly observed for long events with multiple peaks for a given discharge sediment yields in august and september when the catchment was almost completely covered with vegetation were much smaller than during the rest of the rainy season the hysteresis patterns and timing suggest that the sediment availability from the agricultural areas and hillslopes affects sediment yields more strongly than does peak discharge two distinct types of sediment rating curves were observed for the season when the agricultural land was covered with vegetation and when it was not indicating the dominating contribution of land use cover to sediment yields in the catchment the rate of suspended sediment transport in the area was estimated as 25 6 t year 1 ha 1 copyright 2013 john wiley sons ltd

suspended sediment dynamics in a large regulated river over a 10 year period the lower ebro ne iberian peninsula this paper presents a comprehensive assessment of the suspended sediment load for the period 1998 2008 in the lower river ebro ne iberian peninsula one of the most regulated large rivers in europe sediment load estimates are based on continuous discharge and turbidity records calibrated with direct suspended sediment samples covering a wide range of river s hydraulic conditions the temporal variability of the sediment load and the role of the effective discharge at different temporal scales are specifically examined at the log term the study period can be considered as dry mean annual load is estimated at around 0 092 106 t a value that represents less than the 1 of what was transported at the beginning of the twentieth century in the absence of dams and under different land uses in general sediment concentrations observed between 1998 and 2008 are low mean was 9 mg l 1 and maximum was 240 mg l 1 specific sediment yield was in the order of 1 t km2 y 1 also much lower than values reported in other western european rivers of the same scale and impact at the annual scale large floods were responsible for most of the transported suspended sediment up to 80 nevertheless when the effective discharge is calculated for the whole study period floods of moderate magnitude and high frequency are responsible for the largest amount of sediment transport the temporal scale used to calculate the effective discharge thus determines the final results load estimates derived from continuous suspended sediment and discharge data and from the flow duration method yielded similar values this suggests that the latter method is also appropriate when sediment samples cover a large proportion of the observed discharges and statistical significant relations can be obtained and applied to long periods of record this study provides further insights into the sedimentary status of one of the largest rivers in europe results corroborate previous studies highlighting sediment deficit downstream from large dams this type of information constitutes a key element to inform and improve current management and restoration actions

a reassessment of the suspended sediment load in the madeira river basin from the andes of peru and bolivia to the amazon river in brazil based on 10 years of data from the hybam monitoring programme abstract the madeira river is the second largest tributary of the amazon river it contributes approximately 13 of the amazon river flow and it may contribute up to 50 of its sediment discharge to the atlantic ocean until now the suspended sediment load of the madeira river was not well known and was estimated in a broad range from 240 to 715 mt yr 1 since 2002 the hybam international network developed a new monitoring programme specially designed to provide more reliable data than in previous intents it is based on the continuous monitoring of a set of 11 gauging stations in the madeira river watershed from the andes piedmont to the confluence with the amazon river and discrete sampling of the suspended sediment concentration every 7 or 10 days this paper presents the results of the suspended sediment data obtained in the madeira drainage basin during 2002 2011 the madeira river suspended sediment load is estimated at 430 mt yr 1 near its confluence with the amazon river the average production of the madeira river andean catchment is estimated at 640 mt yr 1 30 the corresponding sediment yield for the andes is estimated at 3000 t km 2 yr 1 30 and the average denudation rate is estimated at 1 20 mm yr 1 30 contrary to previous results that had mentioned high sedimentation rates in the beni river floodplain we detected no measurable sedimentation process in this part of the basin on the mamore river basin we observed heavy sediment deposition of approximately 210 mt yr 1 that seem to confirm previous studies but while these studies mentioned heavy sedimentation in the floodplain we showed that sediment deposition occurred mainly in the andean piedmont and immediate foreland in rivers parapeti grande pirai yapacani chimore chapare secure maniqui with discharges that are not sufficiently large to transport their sediment load downstream in the lowlands

temporal distribution of suspended sediment transport in a humid mediterranean badland area the araguas catchment central pyrenees abstract this paper analyses the temporal patterns of suspended sediment yield in the araguas catchment central spanish pyrenees a small experimental catchment with extensive badlands the catchment has been monitored since 2004 to study weathering erosion and hydrological and sediment responses to understand the superficial dynamics of a badland area in a relatively humid environment the development of badlands in the central spanish pyrenees is favoured by the presence of marls and a markedly seasonal climate the continuous observation of selected physical parameters and environmental variables enables us to establish seasonal patterns of weathering processes and identify those factors that control regolith development freeze thaw cycles in winter and wetting drying in spring summer are the main processes involved in regolith weathering thereby controlling slope development in combination with rainfall related erosion processes the 64 floods recorded during the study period december 2005 to january 2007 were used for a hydrosedimentological analysis the main observed features indicate that the araguas catchment reacts to all rainfall events resulting in steep rising and recession limbs on the hydrograph and a very short time lag floods show high suspended sediment concentrations and a heterogeneous temporal distribution related to seasonal variations in surface runoff production these differences increase the degree of complexity involved in studying sediment response suspended sediment concentration and transport mainly depend on rainfall volume maximum rainfall intensity peak flow and runoff occurrence finally the similarities among the obtained hydrographs sedigraphs and hyetographs in combination with the rapid response of most of the floods suggest a large contribution of overland flow derived mainly from infiltration excess runoff upon badland areas accordingly the significant correlations obtained between rainfall intensity and sediment concentration mainly during the dry season which suggest a single source area for both runoff and sediment also support the hypothesis of hortonian hydrological response within badland areas

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

combining suspended sediment monitoring and fingerprinting to determine the spatial origin of fine sediment in a mountainous river catchment an excess of fine sediment grain size 2 mm supply to rivers leads to reservoir siltation water contamination and operational problems for hydroelectric power plants in many catchments of the world such as in the french alps these problems are exacerbated in mountainous environments characterized by large sediment exports during very short periods this study combined river flow records sediment geochemistry and associated radionuclide concentrations as input properties to a monte carlo mixing model to quantify the contribution of different geologic sources to river sediment overall between 2007 and 2009 erosion rates reached 249 75 t km 2 yr 1 at the outlet of the bleone catchment but this mean value masked important spatial variations of erosion intensity within the catchment 85 5000 t km 2 yr 1 quantifying the contribution of different potential sources to river sediment required the application of sediment fingerprinting using a monte carlo mixing model this model allowed the specific contributions of different geological sub types i e black marls marly limestones conglomerates and quaternary deposits to be determined even though they generate locally very high erosion rates black marls supplied only a minor fraction 5 20 of the fine sediment collected on the riverbed in the vicinity of the 907 km2 catchment outlet the bulk of sediment was provided by quaternary deposits 21 66 conglomerates 3 44 and limestones 9 27 even though bioengineering works conducted currently to stabilize gullies in black marl terrains are undoubtedly useful to limit sediment supply to the bleone river erosion generated by other substrate sources dominated between 2007 and 2009 in this catchment

source storage and mobilisation of fine sediment in a chalk stream system concern for sediment problems in the upper river piddle dorset including accumulation of fine sediment on the channel bed and elevated turbidity levels during periods of stable flow provided the stimulus for a detailed field investigation of the sediment dynamics of this chalk stream system undertaken during the period november 1991 to april 1993 two monitoring stations were established at south farm piddletrenthide and lawrence mede piddlehinton and estimates of suspended sediment load were obtained for these two sites in addition suspended sediment concentrations and bed sediment loadings were regularly sampled at several other sites sediment traps were deployed at ten representative sites along the river channel field observations of sediment sources and pathways were made during storm events and a sediment source fingerprinting study was undertaken estimates of annual suspended sediment yield provided values of 9 12 t km 2 year 1 which must be seen as low by uk standards elevated suspended sediment concentrations were not restricted to storm events but occurred throughout the monitoring period in response to remobilisation of sediment stored in the channel the evidence provided by the sediment loads recorded at the two monitoring stations by the sediment traps and by the measurements of bed sediment loading indicated that substantial amounts of sediment accumulated in the channel of the upper and middle reaches of the river during the winter months and that this slug of sediment was slowly transmitted downstream during the following summer fingerprinting of the transported sediment and of potential sources indicated that the dominant source of suspended sediment was likely to be surface soil from cultivated areas field reconnaissance surveys undertaken during storm events indicated that substantial inputs of surface runoff and suspended sediment entered the stream much of this sediment is however stored within the channel system and slowly transmitted downstream copyright 1999 john wiley sons ltd

temporal changes in suspended sediment transport in an atlantic catchment nw spain catchment scale suspended sediment ss transport studies in northwest spain are of special interest as little research at this scale has been done in this region however the role of sediments in the transfer of nutrients and contaminants to coastal areas in this region has been highlighted data were collected from the corbeira catchment during a 3 year period and the variability in ss load at different temporal scales within events variability monthly seasonal and annual was analyzed the statistical relationship between discharge and suspended sediment concentration ssc from samples obtained every 15 days as well as during runoff events in october 2004 to september 2007 showed a marked scatter of points hence the rating curve method does not seem appropriate to estimate ssc in this catchment the results also demonstrated that at the within events scale most of the ss peaks preceded the discharge peaks 70 of runoff events implying that zones nearby or well connected to the stream are the dominant sediment source areas in some cases rills and ephemeral gullies developed in cropland were the main source of sediment delivered to the stream furthermore a reduction in ssc was observed in sequences of events which can be mainly linked to a phenomenon of sediment exhaustion at the seasonal scale most of the total annual ss load was transported during the autumn months the period in which generally the largest number of events occurred while in the summer total annual ss load was very low 1 at the annual scale specific ss yield ssy ranged from 5 4 to 11 2 mg km 2 y 1 the variability in ssy was correlated with the number and magnitude of runoff events recorded yearly since runoff events dominated ss transport and yield for instance in the last hydrological year 2006 07 more than 80 of the ss load was exported in runoff events involving 10 of the time

flood based analysis of high magnitude sediment transport using a non parametric method francke t lopez tarazon j a vericat d bronstert a batalla r j 2008 flood based analysis of high magnitude sediment transport using a non parametric method earth surface processes and landforms 33 13 2064 2077 sponsorship sesam catalan government european social fund

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

conceptual assessment of dis connectivity and its application to the ganga river dispersal system abstract connectivity in river dispersal systems is an important evolving concept and helps in understanding their dynamics in this study the types of connectivity have been defined on the basis of two components namely physical contact and transfer of material based on this four types of connectivity are recognized these are a active connected system b inactive connected system c partially active connected system and d disconnected system connectivity indices have been proposed based on the process understanding of different types of connectivity this conceptual understanding of connectivity has been applied to the ganga dispersal system a large river system results of the connectivity analysis on the ganga dispersal system reveal that different sets of data such as sediment budgets geochemical isotopic data and radiogenic 238 u 234 u 230 th data are noncoherent therefore developing rigorous and well constrained quantitative multidisciplinary data sets is needed to have a better understanding of connectivity at multiple spatio temporal scales in large river dispersal systems this would ultimately help model the dynamics of such systems