sediment trapping characteristics of a pit trap and the helley smith sampler in a cobble gravel bed river 1 although designed for granule gravels the helley smith hs bed load sampler is often used in streams with much coarser beds to compare magnitudes and grain size distributions of sediment samples collected by a pit trap and a standard hs sampler we conducted 22 sampling events over a wide range of flows during a snowmelt freshet in a stream with a coarse gravel bed each sampling event consisted of three simultaneous measurements one made with a pit trap installed in the bed one with a hs sampler placed on the bed directly beside the pit trap hs i and one with a hs sampler placed on the downstream rim of the pit trap hs p we summed the catches of the pit trap and hs p to estimate actual bed load transport the pit trap and hs i catches were then compared to the summed sample the pit trap yielded a remarkably consistent positively skewed sigmoidal distribution of catch efficiency for all 22 measurements with near 100 efficiency for material larger than 2 8 mm the hs i sampler was more variable in its catch and trapping efficiency exhibiting low trapping efficiency for midrange material 0 71 to 16 mm but high efficiency for finer material the results cast doubt on the accuracy of bed load data sets collected by helley smith samplers in coarse gravel channels

particle path characteristics at the large gravel bed river danube results from a tracer study and numerical modelling a tracer study performed on a 3 km long reach of the danube river in austria is presented forty artificial stones of three different sizes intermediate b axis 25 mm 40 mm 70 mm were produced and a coded radio acoustic transmitter was implanted the measurement system had to be improved to be applicable to large rivers with water depths up to 12 m the positions of the stones were observed approximately once a week depending on hydrology over a period of at least one year by radio tracking from a boat including a 15 year flood event transport paths and velocities as well as the incipient motion of bedload transport could be monitored for the first time on a large gravel bed river the particle paths were found to be mostly bankline parallel even though the stones passed a 30 river bend the median of the transverse particle displacement was found to be 4 of the longitudinal displacement calculations considering both transverse slope and transverse flow velocities showed transverse transport to be 6 6 of the longitudinal transport indicating that marginal lateral transport is mainly influenced by morphology a three dimensional 3d numerical model using a stochastic particle tracing approach was validated with the data indicating that the observed positions are well reproduced by the model within the observation period 74 of all stones passed the reach with more than 1000 detections particle transport could be characterized by a mean travel velocity of about 10 m per day variable for the different grain sizes single tracer stones were transported up to 1000 m during a single flood event size selective behaviour could be shown and the incipient motion of the large 70 mm gravel was detected at lower discharges than predicted by commonly used uniform bedload transport formulae copyright 2012 john wiley sons ltd

beryllium geochemistry constraints on the hydraulic behavior of mud volcanoes the trinidad island case to constrain trinidad mud volcanoes hydraulic behavior both cosmogenic 10be t1 2 1 5 myr and 9be concentrations have been measured in fluid and associated expelled mud as previously evidenced a n dia m castrec j boulegue p comeau trinidad mud volcanoes where do the expelled fluids come from geochim cosmochim acta 63 1999 1023 1038 from 18o values and cl concentrations 9be concentrations in the fluids mostly reflect the mixing of two deep components rem i and rem ii rem i 18o 10 5 cl 275 mm and 9be 0 05 nm has characteristics of a continental fluid while rem ii 18o 3 cl 350 mm and 9be 1 nm results from seawater volcanogenic derived sediment interaction although 10be concentrations in the fluid samples are close to the detection limit the distribution of both beryllium isotopes between the hydroxylamine leachable and residual phases indicates exchange reaction with fluid younger than 15 myr comparison between the lowest rem i 10be 9be ratio in fluid recorded by the hydroxylamine leachable phase td5 mud sample and the 10be 9be ratio representative of meteoric contribution in the recharge area td8 fluid sample yields a circulation rate of rem i fluid in the trinidad mud volcanoes of several 10 1 m yr

disturbances in coarse bedload transport in a high mountain stream channel system western tatras poland abstract bedload transport measurements in the formerly glaciated chocholowski catchment located in the western tatras in poland were performed in the period 1975 to 2018 measurement of bedload displacement allowed to determine the role of bedload transport disturbances in both system connectivity and sediment transfer bedload transport occurred as many as triggered up to several times a year the longest distances were observed during rain on snow events between 12 m in headwaters and over 100 m in the fluvial valley bedload became activated along the entire length of the channel system 10 5 km every 2 to 5 years when the stream discharge exceeded 10 m3 s 1 with an average of 1 25 m3 s 1 in such situations bedload dynamics increased downstream and stream power was sufficient to overcome local barriers i e boulder and log steps downstream increases in bedload dynamics may become disturbed and inverted by sudden snowmelt and locally heavy rainfall these types of events caused the dynamics of bedload transport to be 190 to 320 greater in the upper part of the studied catchment and to decline in the downstream direction over a distance of 7 km to yield an attenuation effect the same pattern was observed in local tributaries where the dynamics of bedload transport were 200 higher in the upper part and attenuation was observed along a distance of 1 5 km in the downstream direction all events of this type cause seasonal disturbances in bedload transport however the greatest effect on bedload dynamics was produced by natural deforestation a 16 decrease in forest cover causes a fluvial system disequilibrium manifested in an intensification of hydro geomorphologic processes and formation of new landforms

benefits of design modifications to the birkbeck bedload sampler illustrated by flash floods in an ephemeral gravel bed channel the benefits of three simple modifications to the design of a birkbeck bedload slot sampling system that has been continuously operating in nahal eshtemoa israel since the early 1990s are demonstrated the modifications include the deployment of a removable slot cover which delays the accumulation of sediment so allowing sampling at late stages of a flood and in conjunction with other samplers extending the period of sampling during a flood wave inclusion of a slot the size of which is adjustable so that that the probability of sampling the largest clast sizes in transit as bedload can be increased post installation once knowledge is gained about the bedload grain size distribution and a sampler side wall door that allows stratification and textural changes within the accumulated bedload to be identified so promoting intelligent sampling of the deposit for grain size determination results from seven flash floods are presented and discussed with recommendations for bedload monitoring particularly in rivers where sediment flux is high and dynamic sediment records are inevitably short because of instrumental limitations copyright 2006 john wiley sons ltd

radon variations at arrowhead and murrieta springs continuous and discrete measurements two continuous radon monitors crms have been deployed at arrowhead hot springs along the san andreas fault near san bernardino and at murrieta hot springs along the elsinore fault the recorded hourly and daily radon variations during 1983 are within 5 of the mean values the radon levels increased however by about 10 20 above their normal baseline levels in midyear several small magnitude earthquakes m 3 0 3 5 occurred within 20 km of the arrowhead site near the end of the period of the radon increase

joint sensing of bedload flux and water depth by seismic data inversion rivers are the fluvial conveyor belts routing sediment across the landscape while there are proper techniques for continuous estimates of the flux of suspended solids constraining bedload flux is much more challenging typically involving extensive measurement infrastructure or labour intensive manual measurements seismometers are potentially valuable alternatives to in stream devices delivering continuous data with high temporal resolution on the average behaviour of a reach two models exist to predict the seismic spectra generated by river turbulence and bedload flux however these models require estimating a large number of parameters and the spectra usually overlap significantly which hinders straightforward inversion we provide three functions contained in the r package eseis that allow generic modelling of hydraulic and bedload transport dynamics from seismic data using these models the underlying monte carlo approach creates lookup tables of potential spectra which are compared against the empirical spectra to identify the best fitting solutions the method is validated against synthetic data sets and independently measured metrics from the nahal eshtemoa israel a flash flood dominated ephemeral gravel bed river our approach reproduces the synthetic time series with average absolute deviations of 0 01 0 04 m water depth ranging between 0 1 m and 0 00 0 04 kg sm bedload flux ranging between 0 4 kg sm the example flash flood water depths and bedload fluxes are reproduced with respective average deviations of 0 10 m and 0 02 kg sm our approach thus provides generic testable and reproducible routines for a quantitative description of key metrics hard to collect by other techniques in a continuous and representative manner

an advanced signal processing technique for deriving grain size information of bedload transport from impact plate vibration measurements a reliable characterization of bedload transport is required to gauge the engineering and theoretical issues related to the dynamics of sediments transport in rivers however while significant advances have been made in the development of monitoring techniques robust quantitative predictive relationships have proven difficult to derive in this article we develop a dedicated signal processing technique aimed at improving the usage of impact plate measurements for material transport characterization our set up consists of a piezoelectric hydrophone mounted on the bottom side of a stainless steel plate thus acting as a sediment vibration sensor while the classical analysis with such systems is usually limited to rather simple procedures such as impact counting a large amount of useful information is contained in the actual waveform of the impact signal which conveys the force and the contact time that the bedload imposes on the plate an advanced signal processing technique called first arrival atomic decomposition is used to improve the characterization of bedload transport by analysing the amplitude and frequency attributes of each single impact this new processing approach proves to be well suited for bedload transport monitoring using plate systems and allows us to establish a relationship between the median grain size d50 and the impact signal properties this link is first observed and validated with controlled flume experiments and then applied to continuous impact records in a small gravel bed river during a flood event the estimated d50 offers a novel possibility to observe the time varying grain size distribution of bedload transport copyright 2014 john wiley sons ltd

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

analysis and classification of bedload transport events with variable process characteristics abstract knowledge about the magnitude of bedload fluxes at given hydraulic conditions in natural streams is essential for improved process understanding for the application calibration and validation of bedload transport formulas and for numerical sediment transport models nonetheless extensive field measurements of bedload transport are challenging and therefore data from such efforts are rare bedload transport has been measured comprehensively at the downstream section of the urslau torrent in salzburg austria since 2011 we used an integrative monitoring system that combines direct mobile basket sampler slot sampler and indirect measuring devices geophone plates continuous information about the intensity and distribution of bedload transport within the channel cross section is available in high spatial and temporal resolution seven geophone plates at a stream width of 8 m are part of a measurement system that delivers data in 1 min intervals these geophone data are calibrated using results of direct bedload measurements providing an opportunity to calculate bedload rates and bedload yields in selected time periods continuous data on the bedload transport process over three years enabled assessing several bedload transport events the investigation of bedload transport rate discharge relationships reveals order of magnitude changes for individual events we observed shifts in the data reflecting different bedload rates at comparable hydraulic conditions this study reveals that variable sediment supply conditions affect the prevailing bedload transport rates at the urslau stream calculating the bedload transport efficiency enables comparing bedload transport events that exhibit similar process characteristics finally we provide a conceptual model of bedload transport process types as a function of bedload transport efficiency and dimensionless stream power

bed load transport measurements with geophones and other passive acoustic methods abstractthis paper reviews the more widely used bed load surrogate acoustic measuring techniques that were tested both in flume experiments and field settings a fair number of these measuring tech

geochemical precursors to seismic activity studies of earthquake precursory phenomena during the last several decades have found that significant geophysical and geochemical changes can occur prior to intermediate and large earthquakes among the more intensely investigated geochemical phenomena have been 1 changes in the concentrations of dissolved ions and gases in groundwaters and 2 variations in the concentrations of crustal and mantle volatiles in ground gases the concentration changes have typically showed no conanomalies trend either increasing or decreasing and the spatial and temporal distribution of the observed anomalies have been highly variable as a result there is little agreement on the physical or chemical processes responsible for the observed anomalies mechanisms proposed to account for precursory groundwater anomalies include ultrasonic vibration pressure sensitive solubility pore volume collapse fracture induced increases in reactive surfaces and aquifer breaching fluid mixing precursory changes in soil gas composition have been suggested to result from pore volume collapse micro fracture induced exposure of fresh reactive silicate surfaces and breaching of buried gas rich horizons an analysis of the available field and laboratory data suggests that the aquifer breaching fluid mixing ab fm model can best account for many of the reported changes in temperature dissolved ion and dissolved gas concentrations in groundwater ultrasonic vibration and pressure sensitive solubility models cannot reasonably account for the geochemical variations observed and although the pore collapse model could explain some of the observed chemical changes in groundwater and ground gas uncertainties remain regarding its ability to generate anomalies of the magnitude observed other geochemical anomalies in particular those associated with hydrogen and radon seem best accounted for by increases in reactive surface areas irsa model that may accompany precursory deformation around the epicenter of an impending earthquake analysis of the probable response of these models to the earthquake preparation process as well as to other environmental factors suggests that geochemical monitoring programs can provide information that may be valuable in forecasting the probability of an earthquake however because of the complexity of the earthquake preparation process the absolute prediction of seismic events using geochemical methods alone does not presently appear to be feasible

radium 226 and radon 222 in southern california groundwaters spatial variations and correlations as part of the radon and helium monitoring program for earthquake prediction studies in southern california concentrations of radium 226 in groundwaters have been measured along the major fault zones including the palmdale area radium was measured in order to obtain information on its spatial variation as well as baseline levels several measurements were made at selected sites to examine their temporal variations radium concentrations are used to define the portion of radium supported radon in the observed groundwater radon radium levels vary spatially by 4 orders of magnitude 0 015 to 146 dpm kg but temporally by a factor of 2 or less similar spatial and temporal variations are observed in groundwater radon 60 to 46 700 dpm kg the radon radium activity ratio ranges from 10 to 105 these values indicate that radon is in large excess over radium in groundwaters because of radon diffusion from the ambient rocks the spatial variations of radon radium and the activity ratio are probably due to different chemical and physical properties of the rocks through which groundwaters flow the dependence of groundwater radium concentrations on the water temperature and conductivity is explored it appears that radium increases in general with conductivity but not necessarily with temperature radium is probably leached more readily into the groundwater when the water is more conductive with more dissolved chemical constituents

trinidad mud volcanoes where do the expelled fluids come from abstract in order to establish the origin of fluids expelled from mud volcanoes in trinidad we analyzed their major element trace element and isotopic h o sr compositions the mineralogical chemical and sr isotope compositions of associated expelled muds were also determined on the basis of their chemical and sr isotope compositions the fluids were divided into two groups those southwest and northeast of a major right lateral wrench fault the los bajos fault that both controls the chemical quality of the fluids and acts as a drain strontium isotopes were derived via mixing between a radiogenic source 0 71135 and a nonradiogenic source 0 70671 for both southwest and northeast groups however the nonradiogenic source possibly feeding the northeast group showed a lower sr concentration than that of the southwest group h and o isotope data show that the fluids became enriched in 18 o through interaction with wall rocks the fluids were originally oceanic but their properties were subsequently modified by diagenesis as evidenced by chemical data and mixing between fluids issued from two deep seated reservoirs and surface aquifer end members the gas phase expelled with the mud and the fluid through the mud volcanoes is composed mainly of methane with minor carbon dioxide the amount of expelled gas seems the same in samples from both sides of the los bajos fault the almost unique methane content of the gas phase and the large positive 18 o shifts of the reservoir end member as well as b li and ba contents reveal that the fluids from the deep seated reservoirs inherited their chemical compositions at high temperature fluid rock interactions estimates of equilibrium temperatures of the two deep seated reservoirs suggest that to acquire the estimated higher temperature 150 c the mud volcanoes must have been fed partly by a reservoir located at a depth of more than 3 km this depth corresponds to previous geologic information which located the deep seated reservoir in miocene sediments at such a comparable depth the mixing of the original fluids with a less deep seated reservoir and meteoric waters on the ascending path suggests the presence of a recharge mechanism and contributes to the dynamics of the expulsion itself

morpho textural implications to bedload flux and texture in the sand gravel ephemeral poveda gully abstract we report on channel morpho texture and bedload transport in a natural steep sand gravel ephemeral channel draining the small poveda gully watershed in the mining area of the alto tajo natural park spain first ever continuous bedload flux and texture monitoring in a transitional sand gravel environment was undertaken by two independent reid type slot samplers morphological changes in the feeder reach have been quantified by tls terrestrial laser scanning and sfm structure from motion technologies we identified a pattern in channel bed morphology and texture morpho texture when the channel is incised its texture is coarser otherwise sand filling occurs these changes determine bedload flux and texture sand fill brings rise to high fluxes and fine grained bedload whereas incision caused by evacuation of sand leaves a sandy gravel surface with lower bedload fluxes and coarser texture a video camera recording during events allowed identification of dramatic changes in bedload flux and texture owing to the appearance and erosion of bars supplying field evidence to explain the difficulty in the prediction of bedload flux at short time intervals

continuous measurement of sediment transport in the erlenbach stream using piezoelectric bedload impact sensors we report on bedload transport observations using piezoelectric bedload impact sensors pbis an indirect method of estimating the volume of bedload transport of coarse sediment the pbis device registers vibrations produced by bedload particle diameter 20 mm and records the signal as a sum of the number of impulses per time sediment transport at the erlenbach stream has been continuously monitored with a pbis array starting in 1986 the sensor array spans the width of an entire cross section and is mounted flush with the surface of a check dam immediately upstream of a sediment retention basin we compare pbis data with long term sedimentation records obtained from repeated surveys of material stored in the sediment retention basin with artificial sediment input under controlled conditions in the field and also with laboratory experiments the rate of bedload transport is proportional to the number of impacts on the sensor per unit time the reliability of the calibration relationship increases with the length of the observation period e g for higher numbers of impacts and larger bedload volumes sediment volumes for individual flood events estimated with the pbis method are in agreement with volumes estimated using an independent empirical method based on the effective runoff volume of water the peak water discharge and the critical discharge for the onset of sediment transport copyright 2007 john wiley sons ltd

continuous monitoring of bedload discharge in a small steep sandy channel this paper reports on bedload flux and texture monitored in a natural steep sandy ephemeral channel draining a small gullied sandy watershed the barranca de los pinos 1 32 ha spain bedload flux was continuously monitored with two independent reid type slot samplers bedload texture was determined from the sediment collected in the samplers channel morphology was surveyed with a high spatial resolution with a terrestrial laser scanner the monitored instantaneous bedload fluxes are among the highest measured in natural rivers characterized by high temporal and spatial variability related to the presence of bedforms shallow bars and sand sheets and to the reworking of the dry bed between and at the end of individual flow events the grain size distribution of the bedload indicates equal mobility but bedload texture fluctuates depicting the transport of coarser bar surfaces and of finer grained anabranch surfaces as well as of the overall bed subsurface

beryllium isotope geochemistry in tropical river basins abstract the distributions of beryllium 9 and beryllium 10 in rivers within the orinoco and amazon basins have been examined to extend our understanding of their geochemical cycles and to develop their use both in geochronometry and in studying erosional processes beryllium 9 the stable isotope is weathered from mineral lattices before entering the riverine dissolved or exchangeable phase the cosmogenic radioisotope 10be t 1 2 1 5 myr is produced primarily in the atmosphere and is brought into riverine systems via rainfall in dissolved or exchangeable form it may be used to examine the processes which affect beryllium partitioning between the dissolved and particulate phases ancillary data such as major ion distributions provide a basis for selecting regions in which riverine chemistry is dominated by a single geochemical process allowing examination of its effects on be distributions in isolation analyses of 9be in dissolved and suspended material from rivers with a wide range of chemical compositions indicate that its geochemistry is primarily controlled by two major factors 1 1 its abundance in the rocks of the watershed and 2 2 the extent of its adsorption onto particle surfaces the relative importance of these parameters in individual rivers is determined by the extent of interaction with flood plain sediments and the riverine ph this understanding of 9be geochemistry forms a basis for examination of the geochemical cycling of 10be in rivers which are dominated by interaction with sediments the riverine concentration of dissolved 10be is far lower than that in the incoming rainwater indicating that a substantial proportion of it is retained within the soils of the basin or is adsorbed onto riverine particles however in acidic rivers in which the stable dissolved be concentration is determined by the be level in the rocks of the drainage basin dissolved 10be has essentially the same concentration as in precipitation these observations imply that the soil column in such regions must be saturated with respect to 10be and that the ratio of the inventory to the flux does not represent an age as may be the case in temperate latitudes but rather a residence time

mud volcano field seaward of the barbados accretionary complex a deep towed side scan sonar survey a 30 km2 diapiric field has been identified near 13 50 n up to 12 km seaward of the deformation front of the barbados accretionary complex using a deep towed side scan sonar with a 3 5 khz profiler we identified 31 different diapiric structures based on seismic stratigraphy we show that this field has been active for 200 000 years and that it is a transient feature triggered by the seaward propagation of the high pore fluid pressure associated with the decollement beneath the accretionary complex both basement and decollement in this area are anomalously shallow due to the presence of a n110 basement ridge the height of the diapirs above seafloor does not exceed 40 50 m and can be related to the pressure head of the mud below the decollement two types of structures are identified mud volcanoes and massively emplaced diapirs and ridges on the one hand enigmatic circular very flat mud pies and conical mounds on the other hand the second type of structures has steeper slopes and appears to be associated with very active venting as confirmed by a submersible exploration reported in a companion paper le pichon et al this issue b the venting results in the formation of a stiff carbonate crust and of large subsiding basins around the mud pies continuous active fluid expulsion through these structures indicates that an efficient piping system still connects them to the zone of anomalously high pore pressure below the protodecollement

radon concentrations in soil gas considering radioactive equilibrium conditions with application to estimating fault zone geometry a calculation method for determining the amount of rn isotopes and daughter products at the start of measurement cras is proposed as a more accurate means of estimating the initial rn concentration in soil gas the cras utilizes the decay law between 222rn and 220rn isotopes and the daughter products 218po and 216po and is applicable to scintillation counter measurements as rn is both inert and chemically stable it is useful for fault investigation based on the soil gas geochemistry however the total number of particles emitted by the decay of rn has generally been considered to be proportional to the initial rn concentration without considering the gas condition with respect to radioactive equilibrium the cras method is shown to be effective to derive rn concentration for soil gases under both nonequilibrium conditions in which the total number of decays increases with time and equilibrium conditions which are typical of normal soil under low gas flux the cras method in conjunction with finite difference method simulation is applied to the analysis of two active fault areas in japan and it is demonstrated that this combination could detect the sharp rises in 222rn concentrations associated with faults the method also allows the determination of fault geometry near the surface based on the asymmetry variation of the rn concentration distribution when coupled with a numerical simulation of 222rn transport the results for the new method as applied to the two case studies are consistent with the data collected from the geological survey it implies that the cras method is suitable for investigating the fault system and interstitial gas mobility through fractures the present analyses have also demonstrated that high rn concentrations require the recent and repeated accumulation of 222rn parents 230th and 226ra in fault gouges through deep gas release during fault movement

passive acoustic monitoring of bed load discharge in a large gravel bed river surrogate technologies to monitor bed load discharge have been developed to supplement and ultimately take over traditional direct methods our research deals with passive acoustic monitoring of bed load flux using a hydrophone continuously deployed near a river bed this passive acoustic technology senses any acoustic waves propagated in the river environment and particularly the sound due to interparticle collisions emitted during bed load movement a data set has been acquired in the large alpine gravel bedded drau river analysis of the short term frequency response of acoustic signals allows us to determine the origin of recorded noises and to consider their frequency variations results are compared with ancillary field data of water depth and bed load transport inferred from the signals of a geophone array hydrophone and geophone signals are well correlated thanks to the large network of deployed geophones analysis of the spatial resolution of hydrophone measurements shows that the sensor is sensitive to bed load motion not only locally but over distances of 5 10 m 10 20 of river width our results are promising in terms of the potential use of hydrophones for monitoring bed load transport in large gravel bed rivers acoustic signals represent a large river bed area rather than being local hydrophones can be installed in large floods they can be deployed at a low cost and provide continuous monitoring at high temporal resolution

mud volcano field seaward of the barbados accretionary complex a submersible survey we describe a 0 55 km2 semicircular mud pie and three adjacent diapiric mounds explored using the submersible nautile near 13 50 n 12 km seaward of the barbados accretionary complex deformation front this diapiric field had been previously explored with an acoustically navigated deep towed side scan sonar thus providing an accurate base map the mud pie is situated at a depth of 4938 m in addition to visual observations water rock sediment and biological sampling we measured temperature gradients and made geochemical analyses of the samples fluid venting associated with chemosynthetic animal communities is widespread on all four structures but is maximal in the central third of the mud pie the chemosynthetic life distribution on the mud pie displays a concentric zonation which we relate to an increase in venting activity toward the center as evidenced by thermal gradients recent mud flows are present in the centralmost part of the mud pie the simplest interpretation of the structure is that it is a mud lake covered by a mechanically resistant carbonate crust we determine that approximately 106 m3 of fluid are advected upward through the crust of the mud lake every year this large amount of fluid implies large scale lateral transport

design and calibration of a recording bedload trap this paper reports design modifications to the recording bedload trap developed by reid et al 1980 and rigorous calibration procedures followed both before and after installation an unexpected temperature dependence of the trap and stage pressure transducer records is identified and corrected the consequences of this dependence for the interpretation of a bedload transport event are discussed

bed load bias comparison of measurements obtained using two 76 and 152 mm helley smith samplers in a gravel bed river 1 we assess how the size of the helley smith hs bed load sampler nozzle affects the accuracy of bed load sampling semitheoretical considerations show that the larger grains resident on the streambed can influence the sample either by blocking the sampler entrance or by causing the sampler to rest in a perched position probabilities for interference can be derived from the distribution of grain sizes but they do not capture the actual complexity of the influence of the bed on sampler performance we therefore make an empirical comparison of sediment trapped by hs samplers with 76 and 152 mm intakes during floods in the gravel bed lower ebro river most bed load rates appeared higher when sampled with the hs152 the largest clasts collected by the hs76 also tend to be smaller than those obtained with the hs152 at the same flow analyzing paired bed load samples we find the probability of a bed load sample collected with the hs152 to be biased is around 43 in the conditions of the present study whereas 65 of samples were biased when obtained with the hs76 the analysis emphasizes the influence of bed material texture over sampler performance and demonstrates that the use of samplers with intake size much larger than bed grain size i e 5d will increase the accuracy of bed load grain size distributions and the precision of annual load estimates in gravel bed rivers

measuring bed load transport rates by grain size fraction using the swiss plate geophone signal at the erlenbach abstractthe swiss plate geophone system is a bed load surrogate monitoring technique that is used to quantify bed load transport in steep streams the amplitude of the signal recorded by the swiss plate geophone contains information about the grain size distribution of the transported bed load to extract this information the authors computed the number of impulses and packets representing a single particle impact registered for different amplitude ranges the so called amplitude histograms for 46 samples when bed load was measured independently with automatic basket samplers at the erlenbach amplitude histograms can be interpreted as a statistical distribution of the signal s amplitude over a given time interval using the number of bed load particles per unit mass absolute bed load masses for each grain size class can be calculated the results show that the grain size distribution of the transported bed load for particles larger than 9 5 mm can be continuously monitored at the erlenbach with the

radium geochemistry of ground waters in paleozoic carbonate aquifers midcontinent usa the purpose of this study was to elucidate the processes controlling the distribution and behavior of the longerlived ra isotopes in continuous paleozoic carbonate aquifers of parts of missouri kansas and oklahoma activities of 228 ra and 226 ra were analyzed in fresh and saline ground waters brines and rocks the fluids have a wide salinity range 200 250 000 mg l 1 total dissolved solids the 226 ra activity ranges from 0 66 7660 dpm kg 1 and correlates with salinity and other alkaline earth element ca sr and ba concentrations the range of 228 ra 226 ra ratios in the fluids 0 06 1 48 is similar to that in the aquifer rocks 0 21 1 53 the relatively low mean fluid 228 ra 226 ra ratio 0 30 reflects the low th u ratio of the predominant carbonate aquifer rock radium occurs mostly r77 as ra 2 species in the fluids salinity dependent sorption desorption processes with log k values from 10 0 10 4 and negatively correlated with salinity involving th enriched surface coatings on aquifer flow channels can explain the rapid solid fluid transfer of ra isotopes in the system and the correlation of ra with

10be and 9be in marine sediments and their potential for dating using sequential leaching experiments we have measured the fraction of the cosmogenic isotope 10be half life 1 5 my and its stable isotope 9be co extracted with the following phases in marine sediments exchangeable calcium carbonate fe and mn oxyhydroxides organic opal and detrital the extraction of the authigenic phases typically release 70 of the 10be but only 40 of the 9be in order to test its potential for dating marine sediments we have measured the authigeniccally associated 10be 9be in 17 surface sediment samples from different ocean basins the observed spatial variability which appears to be influenced by proximity to continental input of 9be precludes the general and precise applications of leached 10be 9be for dating however the relatively constant value observed in surface sediments over large areas of the pacific indian and southern atlantic oceans shows considerable promise for approximate dating of open oceans sediments in order to test temporal variability a profile of the authigenically associated 10be 9be ratio has been measured in the independently dated central pacific core rc12 65 the observed variation in 10be 9be over the past nine my is approximately twice that expected on the basis of 10be decay alone several possible explanations for such behavior and their potential consequences for the use of leached 10be 9be for dating are discussed

bed load texture in an alpine gravel bed river the spatial and temporal variations in bed load texture measured in a gravel bed river with a helley smith sampler are compared with its bed material texture most measurements were undertaken at low excess shear stress with low bed load discharge over an armored bed cross sectionally averaged fractional bed load discharge increases with water discharge but the explanation of the variance in fractional discharge is low 20 40 cross sectional distribution of shear velocity explains in part the spatial variation in bed load texture because local hydraulic parameters are weak predictors of fractional bed load discharge for the granule pebble range at nonequilibrium conditions it reinforces the hypothesis that this size range which comprises the bulk of bed load derives from upstream sources temporal variations in the cross sectional distribution of bed load texture are shown to depend on variations in bed topography and local shear stress we demonstrate that the dominance of granule pebble fractions is in part related to the hiding behavior of smaller fractions

geophysical survey of a mud volcano seaward of the barbados ridge accretionary complex a detailed geophysical investigation that included multibeam bathymetry 3 5 khz channel and single channel seismic profiles 20 heat flow measurements and four piston cores was made of a mud volcano located about 8 km seaward of the toe of the barbados ridge accretionary complex in the northern guiana basin the material erupted from the volcano covers an oval area about 3 9 km with its long axis oriented e w roughly perpendicular to the deformation front a flat topped mound on the western side of the feature is the currently active center acoustic stratigraphy suggests that mud volcanism began at the site about 200 000 ma a piston core taken on the flank of the active mound sampled deposits erupted 20 000 30 000 ma that contain late miocene nannofossils heat flow on the active mound is 4 times that in the surrounding basin one dimensional modeling of this anomaly supports a low level continuing flux of mud and water at rates of 2 5 cm yr the mud volcanism appears to have arisen from the combined action of overpressured water that comes from beneath the accretionary prism and existing overpressures in the oceanic section large east west trending basement escarpments underlie the two known mud volcanoes seaward of the barbados ridge accretionary complex and they probably play an important role in developing vertical pathways for fluid to escape and in determining the location where mud volcanism starts

integrated automatic and continuous bedload monitoring in gravel bed rivers bedload monitoring techniques have been developed and applied for many years in rivers ranging from steep mountain torrents to the large gravel bed danube river in austria most monitoring stations use a combination of direct mobile bag samplers slot samplers and indirect geophones hydrophones measurement methods each individual technique is adequate yet features particular boundary conditions and limitations related to hydraulic and sampling efficiency functionality during floods sampling duration or grain size we show the capabilities and limitations of the different monitoring devices with respect to technical operational and economic criteria evaluating their suitability for determining bedload transport parameters bedload monitoring results of a measuring site at the drau river in carinthia austria are used to illustrate the specific range of the device application we present an integrated automatic and continuous bedload monitoring system it complements the specific limitations of single monitoring methods by additional measurement devices enabling comprehensive monitoring of the bedload transport process we then derive the bedload discharge integrated calculation approach and the bedload rating curve approach and discuss their application for determining bedload discharge qb and total bedload mass vb whereas the integrated approach combines data from direct monitoring methods with indirect techniques the rating curve approach uses only data from direct bedload monitoring devices we demonstrate that applying an integrated automatic and continuous bedload monitoring system and combining the bedload discharge integrated calculation approach and bedload rating curve approach yields accurate bedload discharge results

gas geochemistry applied to earthquake prediction an overview terrestrial gases in groundwater and soil air have been extensively studied in recent years in seismically active areas especially in ussr china japan and united states in search of premonitory changes that might be useful for earthquake prediction concentrations of radon helium hydrogen mercury carbon dioxide and several other volatiles have been found generally to be anomalously high along active faults suggesting that the faults may be paths of least resistance for the terrestrial gases generated or stored in the earth to escape to the atmosphere temporal gas concentration changes with durations of a few hours to many months have been observed before many large earthquakes at a relatively small number of favorably situated stations at epicentral distances of up to several hundreds of kilometers these sensitive stations are generally located along active faults especially at intersections or bends of faults or some other structurally weak zones possibly because of tectonic strain concentration at such places however gas concentrations especially those measured at or near the ground surface may also be significantly affected by meteorological hydrological and other nontectonic changes in the environment the nontectonically induced variations must be carefully eliminated or recognized in the search of true earthquake related anomalies

beryllium isotope systematics of submarine hydrothermal systems abstract both 10 be and 9 be concentrations have been measured in a hydrothermal fluid from the sediment starved east pacific rise at 21 n as well as in fluids and associated sediments from the sediment covered guaymas basin and escanaba trough hydrothermal systems the results show that while the 9 be concentrations in fluids from both types of systems are comparable about three orders of magnitude higher than that of the seawater supplying the systems their 10 be concentrations are significantly different the 10 be concentration in the solution emanating from the studied sediment starved hydrothermal system is at least two times lower than that of the pacific bottom water by contrast the 10 be concentration in hydrothermal solutions from sediment hosted environments are enriched over ambient seawater and are at least one order of magnitude higher than that measured in the 21 n fluid the sedimentary cover being the only available source of 10 be in these systems these data demonstrate that 10 be is an unambiguous tracer of interactions between hydrothermal fluids and recent sediments as an example this study examines hydrothermal solutions from the sediment starved mariana trough back arc basin which have compositions similar in many respects to those from sediment hosted environments however these fluids are depleted in 10 be relative to ambient seawater which precludes interaction with recent sediment as the cause of their peculiar chemical composition

bedload transport measurements at the erlenbach stream with geophones and automated basket samplers in the erlenbach stream a pre alpine steep channel in switzerland sediment transport has been monitored for more than 25 years near the confluence with the main valley river stream flow is monitored and sediment is collected in a retention basin with a capacity of about 2000 m3 the basin is surveyed at regular intervals and after large flood events in addition sediment transport has been continuously monitored with piezoelectric bedload impact and geophone sensors since 1986 in 2008 2009 the measuring system in the erlenbach stream was enhanced by installing an automatic system to obtain bedload samples movable metal baskets are mounted on a rail at the downstream wall of the large check dam above the retention basin and they can be moved automatically into the flow to take bedload transport samples the wire mesh of the baskets has a spacing of 10 mm to sample all sediment particles coarser than this size which is about the limiting grain size detected by the geophones the upgraded measuring system permits to obtain bedload samples over short sampling periods and to measure the grain size distribution of the transported material and its variation over time and with discharge the analysis of calibration relationships for the geophone measuring system confirms findings from very similar measurements which were performed until 1999 with piezoelectric bedload impact sensors there is a linear relationship between impulse counts and bedload mass passing over the sensors findings from flume experiments are used to discuss the most important factors which affect the calibration of the geophone signal the bedload transport rates as measured by the moving baskets are among the highest measured in natural streams with values of the order of several kilograms per meter per second copyright 2012 john wiley sons ltd

beryllium isotope geochemistry of hydrothermally altered sediments profiles of both10be and9be concentrations have been measured in sediments from the dsdp leg 64 site 477 core established in the deep guaymas basin in an area of high heat flow this site offers the opportunity of studying hydrothermal alteration induced by two distinct hydrothermal systems those caused i by the intrusion of hot sills into porous sediments and ii by heat associated with a magma chamber the results show that the distribution of both beryllium isotopes between two operationally defined sedimentary phases material susceptible to hydroxylamine leaching and residual material changes with the degree of hydrothermal alteration a decrease in10be 9be in the leachable phase of altered sediments relative to unaltered sediments indicates that hydrothermal alteration is not limited to a simple chemical leaching but involves redistribution of the beryllium isotopes between metamorphosed sedimentary phases in addition the similarity of the mean10be 9be ratios associated with the leachable and the residual phases in the part of the core which has experienced greenschist facies metamorphism suggests that this process leads in the prevailing geophysical conditions to isotopic homogenization a close relationship exists between10be and mgo concentrations in altered sediments from this core this supports earlier observations that beryllium is not easily removed from the sedimentary column and indicates that this remains the case even under the conditions encountered in submarine hydrothermal systems

bedload transport measurements with impact plate geophones comparison of sensor calibration in different gravel bed streams indirect bedload transport measurements have been made with the swiss plate geophone system in five gravel bed mountain streams these geophone sensors record the motion of bedload particles transported over a steel plate mounted flush with the channel bed to calibrate the geophone system direct bedload transport measurements were undertaken simultaneously at the erlenbach in switzerland a moving basket sampler was used at the fischbach and ruetz streams in austria a helley smith type bedload sampler provided the calibration measurements a bunte type bedload trap was used at the rofenache stream in austria at the nahal eshtemoa in israel reid type slot bedload samplers were used to characterize the response of the geophone signal to bedload particles impacting on the plate geophone summary values were calculated from the raw signal and stored at one second intervals the number of impulses i e the number of peaks above a pre defined threshold value of the geophone output signal correlated well with field measured gravel transport loads and was found to be a robust parameter the relations of impulses to gravel transport loads were generally near linear but the steepness of the calibration relations differed from site to site by comparing the calibration measurements from the different field sites and utilizing insights gained during preliminary flume experiments it has been possible to identify the main factors that are responsible for site specific differences in the calibration coefficient the analysis of these calibration measurements indicates that the geophone signal also contains some information about the grain size distribution of bedload copyright 2013 john wiley sons ltd

state of disequilibrium between 238u 234u 226ra and 222rn in groundwater from bedrock abstract approximately one thousand drilled wells were investigated for their natural radioactivity the determinations of 238u 234u 226ra and 222rn from 310 samples showed a high state of radioactive disequilibrium between the members of the uranium series present in water the 238 u 226 ra activity ratio usually fell in the range 1 20 and the 238 u 222 rn activity ratio in the range 1 20 10 4 the highest activity ratios being from samples with an elevated uranium content the 234 u 238 u activity ratio varied between 0 76 and 4 67 the most frequent values showing a 60 excess of 234u in the samples most of the 234 u 238 u activity ratios near unity were found in samples with a high uranium content several drilled wells with anomalously high uranium contents were found in southern finland the average 226ra and 222rn contents of these wells were not exceptionally high which suggests high mobility of uranium in groundwater from the areas involved

flume and field based calibration of surrogate sensors for monitoring bedload transport bedload transport assessment is important for geomorphological engineering and ecological studies of gravel bed rivers bedload can be monitored at experimental stations that require expensive maintenance or by using portable traps which allows measuring instantaneous transport rates but at a single point and at high costs and operational risks the need for continuously measuring bedload intensity and dynamics has therefore increased the use and enhancement of surrogate methods this paper reports on a set of flume experiments in which a japanese acoustic pipe and an impact plate have been tested using four well sorted and three poorly sorted sediment mixtures additional data were collected in a glacierized high gradient andean stream estero morales using a portable bunte type bedload sampler results show that the data provided by the acoustic pipe which is amplified on 6 channels having different gains can be calibrated for the grain size and for the intensity of transported sediments coarser than 9 mm r2 0 93 and 0 88 respectively even if the flume based calibration is very robust upscaling the calibration to field applications is more challenging and the bedload intensity could be predicted better than the grain size of transported sediments r2 0 61 and 0 43 respectively the inexpensive impact plate equipped with accelerometer could be calibrated for bedload intensity quite well in the flume but only poorly in the field r2 0 16 and could not provide information on the size of transported sediments

towards the hydrologic and bed load monitoring from high frequency seismic noise in a braided river the torrent de st pierre french alps summary we explore the use of seismic noise produced by rivers to monitor the bed load transport in the case of a low discharge braided river in the french alps the torrent de st pierre for this purpose we deployed two dedicated seismic networks during summers 2007 and 2008 for which the characteristics of the recorded continuous signal are similar despite changes in the sensor locations for dry weather conditions only melting of nearby glaciers controls the supply of water to the stream in these conditions the river hydrology and the seismic energy in the 2 80 hz frequency band both follow a diurnal fluctuation similar to the thermal amplitude in contrast during rainfall episodes the temperature variation fails to explain the hydrodynamic changes dense cloud covers reduce glacier melting and the recorded seismic energy denotes bursts of high frequency seismic noise well correlated with water level data comparisons between the recorded seismic signals and the collected hydrological and sediment load data indicate that a frequency band of 3 9 hz best explains the water level changes and thus the seismic waves coming from the flow turbulence these analyses also reveal the presence of a seismic noise threshold that might be linked to the water shear stress exerted by the flowing water using the seismic energy in this frequency band as a proxy of the fluvial shear stress the seismic hydrologic relationship may be sensitive to variations in bed load transport the spectral content of the seismic energy shows patterns consistent with the mobilization of sediment particles from the interpretations of the seismic wave attenuation of river sources we finally propose that stations at a distance from the stream less than 50 m are able to record most sediment particles farther stations are still useful during extreme events when largest grain sizes are mobilized more generally this study demonstrates the feasibility of using the river seismic signal to survey bed load transport in various river types from small braided mountain rivers like the torrent de st pierre to the large entrenched himalayan rivers

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

impacts of gravel mining and renaturation measures on the sediment flux and budget in an alpine catchment johnsbach valley austria abstract in the johnsbach valley austria a medium size non glaciated torrent catchment enormous amounts of sediment have been made available due to the brittle dolomite bedrock this occurs mainly in the zwischenmauerstrecke zms english translation reach between the walls and presents a major challenge to local river management within a renaturation project which followed several decades of disturbance flood protection and gravel mining in the zms it is of particular importance to understand where the sediments come from and the transport pathways through the system to prepare future forecasts in the present study we investigate the recent sediment cascade in a comprehensive analysis of the zms that was achieved by means of airborne laser scanning campaigns in 2010 and 2015 the current bedload yield at the outlet was measured using an integrative bedload monitoring system historical data from 1954 was used to illustrate the effects of the mining period on the former sediment routing finally we evaluated the expected sediment transport rates in the near future the results show that from the hillslopes sediments are mainly transported via the active side trenches to the main channel 7000 m3 yr 1 the sediment transport in the johnsbach river consists mainly in relocating the periodically occurring sediment entries of the side trenches the bedload transport rates at the outlet sum up to annual bedload yields of 2000 m3 yr 1 to almost 12 000 m3 yr 1 during the observation period especially those areas inside the side trenches that were heavily affected by gravel mining excavated amount of sediment during the mining period 25 000 m3 yr 1 are now accumulating sediment since the end of this period 8000 m3 yr 1 future scenarios will depend heavily on the progress in the mining affected side channels the impacts of this period are continuously being reworked and a natural sediment flow will adjust in the near future the sediment input into the johnsbach river will rise significantly and could lead to a doubling in the annual sediment yield at the outlet compared to now in particular the reaches along the johnsbach river following the confluences with the mining affected side trenches are already showing morphological changes due to the recently imported sediments

continuous monitoring of bedload flux in a mountain gravel bed river an automatic bedload monitoring station has been established on the perennial tordera river a mediterranean mountain gravel bed stream located in ne spain bedload fluxes were obtained automatically at 1 min intervals using two birkbeck type pit bedload samplers aligned across the width of the channel flow depth and water surface slope were both measured continuously and synchronously with bedload data for five flow events show that bedload flux varies considerably bedload flux is high when it is compared with other perennial streams for a 15 min interval maximum channel average bedload flux was 0 83 kg m 1 s 1 bedload records also show that there is no direct relationship between bedload flux and grain shear stress the low correlation between bedload flux and hydraulics arises due to the different thresholds of initiation of motion for each flow event and the variable character of the bed between events for two individual floods there is a reasonable relationship between bedload flux and grain shear stress in part as a consequence of individual particle entrainment and patch movement over a stable coarse gravel bed during moderately high discharges these results demonstrate that the birkbeck system functions well in a mediterranean mountain gravel bed stream with a longitudinal slope of 2