historical reconstruction of monthly oceanic precipitation 1900 2006 1 an oceanic precipitation reconstruction is developed and evaluated for periods extending back to as early as 1900 large scale monthly oceanic precipitation is reconstructed using the available network of historical gauge data fit to a set of large scale covariance spatial modes based on modern analysis the modern analysis is based on satellite microwave estimates merged with atmospheric reanalysis estimates for 1900 2006 a monthly and 5 spatial product is developed for reconstructing climate scale large scale spatial and inter seasonal and longer timescales variation in pre satellite periods advantages of this study include the use of a homogeneous satellite analysis for computing reconstruction statistics and improved tuning of the reconstruction methods cross validation testing is used to show how much historical variance can be reconstructed with the available sampling in addition reconstructions are performed using several different gauge data sets to evaluate differences due to the choice of gauge data testing shows that that these improved methods produce reconstructions with useful skill in the tropics and northern hemisphere midlatitudes in the southern hemisphere midlatitudes and in polar latitudes in both hemispheres sampling is too sparse to yield much skill the reconstruction is able to resolve large scale modes of variation useful for some diagnostic studies of the 20th century reconstruction efforts will continue as improved satellite and atmospheric reanalyses become available

sediment production and yield from an alluvial gully in northern queensland australia sediment production transport and yield were quantified over various timescales in response to rainfall and runoff within an alluvial gully 7 8 ha which erodes into dispersible sodic soils of a small floodplain catchment 33 ha along the mitchell river northern australia historical air photographs and recent global positioning system gps surveys and lidar data documented linear increases in gully area and volume indicating that sediment supply has been relatively consistent over the historic period daily time lapse photography of scarp retreat rates and internal erosion processes also demonstrated that erosion from rainfall and runoff consistently supplied fine washload 100 000 mg l and sediment yields 89 to 363 t ha yr were high for both australian and world data total sediment yield estimated from empirical washload and theoretical bed material load was dominated by fine washload 63 m a lack of hysteresis in suspended sediment rating curves scarp retreat and sediment yield correlated to rainfall input and an equilibrium channel outlet slope supported the hypothesis that partially or fully transport limited conditions predominated along the alluvial gully outlet channel this is in contrast to sediment supply limited conditions on uneroded floodplains above gully head scarps while empirical data presented here can support future modelling efforts to predict suspended sediment concentration and yield under the transport limiting situations additional field data will also be needed to better quantify sediment erosion and transport rates and processes in alluvial gullies at a variety of spatial and temporal scales copyright 2013 john wiley sons ltd

linking watershed geomorphic characteristics to sediment yield evidence from the loess plateau of china abstract the geomorphic characteristics of a watershed affect the energy fluxes mass movement and water and sediment dispersion within the watershed this paper examines how watershed complexity affects sediment yield in terms of rainfall and geomorphic characteristics the geomorphic characteristics include primary secondary and compound topographic attributes watershed shape characteristics relief parameters and stream network characteristics because of the high co dependence among these characteristics partial least squares regression plsr was used to identify the relationships between the sediment yield and 29 selected watershed characteristics the plsr combines the features of a principal component analysis and multiple linear regression and is a robust multivariate regression method that is appropriate when the predictors exhibit multiple co linearity the first order factors were determined by calculating the variable importance for the projection vip those variables with high vip values are the most relevant for explaining the dependent variable the results showed that the watershed shape and relief parameters have large influences on the sediment yield the vip values revealed that the sediment yield is primarily controlled by the plan curvature vip 1 87 and the highest order channel length vip 1 53 followed by the hypsometric integral vip 1 49 rainfall vip 1 44 basin relief vip 1 19 slope vip 1 15 sediment transport capacity index vip 1 13 length ratio vip 1 06 profile curvature vip 1 01 and divide average relief vip 1 00 this paper quantified the effects and relative importance of different geomorphic attributes on sediment yield the insight provided by these results can be used in the selection of appropriate geomorphic variables for watershed erosion and hydrological models thus this study is intended to elucidate the internal dynamics of sediment transport and storage in a watershed and provide a guide for watershed management

the propagation of complex flood induced head wavefronts through a heterogeneous alluvial aquifer and its applicability in groundwater flood risk management summary the extraordinary rise of piezometric surface in aquifers may induce an unexpected interaction of groundwater with anthropogenic elements known as groundwater inundation phenomena this could result in several damage processes including building foundation destabilization groundwater infiltration and pollutant remobilization which are responsible for considerable economic losses worldwide to improve our knowledge concerning flood induced head wavefront propagation and groundwater inundation phenomena the reconstructed kinematics of the head wavefronts obtained from a calibrated groundwater model simulating 12 ordinary flood events have been statistically analyzed the correlation between kinematic variables of a flood induced head wavefront flood event characteristics and aquifer properties was the basis for the study of the aquifer response to river flood events along four different trajectories i e the identification of river level rise rate absolute relative height of the maximum rise stage hydraulic parameter variability river aquifer exchange rates pre event state of the aquifer and distance to the aquifer boundary as the key influencing factors in groundwater inundation finally model and scenario results were used to develop two synthetic models for groundwater inundation as novel decision support tools for assessing both ordinary and extraordinary flood events in groundwater flood risk management and in urban development planning these synthetic models gives the technical criteria to predict extraordinary rise of piezometric surface and therefore allows increasing the confidence of stakeholders in the risk assessment and improving the subsurface infrastructure design to mitigate damage processes derived from groundwater interaction

processes spatio temporal factors and measurements of current erosion in the french southern alps a review present erosion in mountainous areas of western europe causes land management problems particularly for areas located downstream of erosion zones except for transalpine roads and ski resorts economic activities no longer require as much space as they did in the past therefore natural reforestation has provided signi cant protection for alpine hillslopes during the 20th century however extreme oods continue to cause severe damage in intra alpine valleys as well as in piedmont and surrounding plains making the study of present water erosion phenomena very important many studies have investigated the processes and factors of water erosion on slopes at both the catchment and plot scales they have focused on rock fragmentation and transportation in different elds the spatial and temporal explanatory variables the consequences downstream ooding sedimentation river bed evolution and the impact of oods in the french alps present erosion has been studied in a variety of outcrops with several recent studies conducted in elds such as marls clayey deposits molasses and moraines these kinds of outcrops are found throughout the alpine massif including an area of special interest on the great jurassic black marl outcrop where badlands are frequently observable geomorphologists and hydrologists have been particularly interested in the strong erosion processes in marls seeking to determine the main patterns and the impact of spatial and temporal factors on soil loss quantities the main climatic factors of rock disaggregation were found to be the freeze thaw and wet dry cycles which destroy rock cohesion and the splash effect of rain the principal site variables are vegetation cover exposure and dip slope angle erosion rates are two or three orders of magnitude higher on bare soils than on pastures northern aspect slopes suffer two to four times as much soil loss as southern aspect slopes finally the angle formed by the slope and the dip also determines different behaviours erosion rates are higher when slope and dip are perpendicular than when they are parallel the transportation agents are mostly debris ows and runoff caused by intense precipitation annual erosion depth in the marls is generally assumed to be substantial up to 10 mm the high value can be explained by the severity of the climatic conditions and the brittleness of the lithology which results in numerous fractures copyright 2003 john wiley sons ltd

mapping of erosion rates in marly badlands based on a coupling of anatomical changes in exposed roots with slope maps derived from lidar data black marls form very extensive outcrops in the alps and constitute some of the most eroded terrains thus causing major problems of sedimentation in artificial storage systems e g reservoirs and river systems in the experimental catchments near draix france soil erosion rates have been measured in the past at the plot scale through a detailed monitoring of surface elevation changes and at the catchment scale through continuous monitoring of sediment yield in traps at basin outlets more recently erosion rates have been determined by means of dendrogeomorphic techniques in three monitored catchments of the draix basin a total of 48 exposed roots of scots pine have been sampled and anatomical variations in annual growth rings resulting from denudation analysed at the plot scale average medium term soil erosion rates derived from exposed roots vary between 1 8 and 13 8 mm yr 1 average 5 9 mm yr 1 and values are significantly correlated with slope angle the dendrogeomorphic record of point scale soil erosion rates matches very well with soil erosion rates measured in the draix basins based on the point scale measurements and dendrogeomorphic results obtained at the point scale a linear regression model involving slope angle was derived and coupled to high resolution slope maps obtained from a lidar generated digital elevation model so as to generate high resolution soil erosion maps the resulting regression model is statistically significant and average soil erosion rates obtained from the areal erosion map 5 8 5 2 and 6 2 mm yr 1 for the roubine moulin and laval catchments respectively prove to be well in concert with average annual erosion rates measured in traps at the outlet of these catchments since 1985 6 3 4 1 and 6 4 mm yr 1 this contribution demonstrates that dendrogeomorphic analyses of roots clearly have significant potential and that they are a powerful tool for the quantification and mapping of soil erosion rates in areas where measurements of past erosion is lacking copyright 2011 john wiley sons ltd

mound development as an interaction of individual plants with soil water erosion and sedimentation processes on slopes in the mediterranean region semi natural shrubland communities named matorral often present a discontinuous cover where isolated perennial plants alternate with bare inter plant areas in such ecosystems the patchy distribution of the vegetation is usually associated with microtopographic sequences of mounds that develop under isolated plants and break the overall slope continuity in this study the influence of three representative species of the mediterranean matorral rosmarinus officinalis stipa tenacissima and anthyllis cytisoides on slope microtopography is determined and the processes that take part in the development of microtopographic structures beneath the plant canopy are identified the influence of slope gradient plant species and plant parameters on the shape and height of microtopographic structures is also studied the shape of the microtopographic structures is described by using a two dimensional microprofilemeter and mound height is determined by measuring in the field a mound height index defined as the distance from the top to the bottom of the mound the results obtained show that plant species play a major role in the shape and height of the microtopographic structures whereas terrace type structures generally develop under anthyllis shrubs microtopographic forms associated with rosmarinus and stipa plants vary with slope gradient the almost symmetric mound type structures that develop under these two species on gentle slopes change into terrace type structures as slope gradient increases moreover statistically significant differences exist between the three species with regard to mound height mean values of mound height are 19 4 14 6 and 4 3 cm under the canopy of stipa rosmarinus and anthyllis respectively plant parameters essentially roughness and slope gradient have a significant influence on mound height index four main processes were identified as affecting mound development in the studied field site sedimentation differential interrill erosion differential splash erosion and bioturbation plant species interact in different ways with these processes according to their morphologies since stipa and rosmarinus plants are more efficient than anthyllis shrubs in controlling water erosion in retaining sediments and in modifying soil properties under their respective canopies they give rise to higher microtopographic structures that facilitate water and nutrient storage by plants on slopes copyright 2000 john wiley sons ltd

varied expressions of the hemispheric circulation observed in association with contrasting polarities of prescribed patterns of variability abstract the low frequency 5 day period variability observed within four different subsets of the climatology h1 l1 h2 and l2 as defined by the high and low index polarities of the two leading principal components pcs of the sea level pressure field is compared with emphasis on distinctive flow configurations and teleconnection patterns the analysis is based on wintertime 500 hpa height sea level pressure and 1000 500 hpa thickness fields derived from the ncep ncar reanalyses for the period of record 1958 99 spaghetti diagrams display specified contours for ensembles of individual 10 day mean charts extracted from the four different subsets of the climatology in l1 10 day mean maps weak zonal flow at latitudes 55 n exhibit larger undulations in the barotropic component of the flow than those in h1 implying larger particle displacements and deeper penetration of arctic air masses particularly into europe and the eastern united states maps in h2 and l2 separated in accordance with

assessment of erosion and deposition in steep mountain basins by differencing sequential digital terrain models abstract digital elevation models dems built from repeated topographic surveys permit producing dem of difference dod that enables assessment of elevation variations and estimation of volumetric changes through time in the framework of sediment transport studies dem differencing enables quantitative and spatially distributed representation of erosion and deposition within the analyzed time window at both the channel reach and the catchment scale in this study two high resolution digital terrain models dtms derived from airborne lidar data 2 m resolution acquired in 2005 and 2011 were used to characterize the topographic variations caused by sediment erosion transport and deposition in two adjacent mountain basins gadria and strimm vinschgau venosta valley eastern alps italy these catchments were chosen for their contrasting morphology and because they feature different types and intensity of sediment transfer processes a method based on fuzzy logic which takes into account spatially variable dtms uncertainty was used to derive the dod of the study area volumes of erosion and deposition calculated from the dod were then compared with post event field surveys to test the consistency of two independent estimates results show an overall agreement between the estimates with differences due to the intrinsic approximations of the two approaches the consistency of dod with post event estimates encourages the integration of these two methods whose combined application may permit to overcome the intrinsic limitations of the two estimations the comparison between 2005 and 2011 dtms allowed to investigate the relationships between topographic changes and geomorphometric parameters expressing the role of topography on sediment erosion and deposition i e slope and contributing area and describing the morphology influenced by debris flows and fluvial processes i e curvature erosion and deposition relations in the slope area space display substantial differences between the gadria and the strimm basins while in the former erosion and deposition clusters are reasonably well discriminated in the latter characterized by a complex stepped structure we observe substantial overlapping erosion mostly occurred in areas that show persistency of concavity or transformation from convex and flat to concave surfaces whereas deposition prevailingly took place on convex morphologies less expected correspondences between curvature and topographic changes can be explained by the variable sediment transport processes which are often characterized by alternation of erosion and deposition between different events and even during the same event

shallow landslide hazard assessment using a physically based model and digital elevation data a model for the analysis of topographic influence on shallow landslide initiation is applied to an experimental mountain basin where high resolution digital elevation data are available the cordon catchment 5 km2 located in northern italy the model delineates those areas most prone to shallow landsliding due to surface topographic effects on hydrologic response the model is composed of two parts a steady state model for shallow sub surface runoff and an infinite slope coulomb failure model which assumes that the soil is cohesionless at failure an inventory of landslide scars is used to document sites of instability and to provide a test of model performance by comparing observed landslide locations with model predictions the model reproduces the observed distribution of landslide locations in a consistent way although spatial variations in soil strength and transmissivity which are not accounted for in the model influence specific distribution of landslide areas within regions of similar topographic control

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

stream floodwave propagation through the great bend alluvial aquifer kansas field measurements and numerical simulations abstract the hypothesis is explored that groundwater level rises in the great bend prairie aquifer of kansas are caused not only by water percolating downward through the soil but also by pressure pulses from stream flooding that propagate in a translatory motion through numerous high hydraulic diffusivity buried channels crossing the great bend prairie aquifer in an approximately west to east direction to validate this hypothesis two transects of wells in a north south and east west orientation crossing and alongside some paleochannels in the area were instrumented with water level recording devices streamflow data from all area streams were obtained from available stream gaging stations a theoretical approach was also developed to conceptualize numerically the stream aquifer processes the field data and numerical simulations provided support for the hypothesis thus observation wells located along the shoulders or in between the inferred paleochannels show little or no fluctuations and no correlations with streamflow whereas wells located along paleochannels show high water level fluctuations and good correlation with the streamflows of the stream connected to the observation site by means of the paleochannels the stream aquifer numerical simulation results demonstrate that the larger the hydraulic diffusivity of the aquifer the larger the extent of pressure pulse propagation and the faster the propagation speed the conceptual simulation results indicate that long distance propagation of stream floodwaves of the order of tens of kilometers through the great bend aquifer is indeed feasible with plausible stream and aquifer parameters the sensitivity analysis results indicate that the extent and speed of pulse propagation is more sensitive to variations of stream roughness manning s coefficient and stream channel slope than to any aquifer parameter

groundwater surface water interaction in lake nasser southern egypt a cross sectional model based on the two dimensional groundwater flow equation of edelman was applied at seven transects distributed over four geological cross sections to estimate groundwater heads and recharge from or groundwater discharge to lake nasser the lake with a length of 500 km and an average width of 12 km was created over the period 1964 1970 the time for constructing the aswan high dam ahd the model constrained by regional scale groundwater flow and groundwater head data in the vicinity of the lake was successfully calibrated to timeseries of piezometeric heads collected at the cross sections in the period 1965 2004 inverse modeling yielded high values for the horizontal hydraulic conductivity in the range of 6 0 to 31 1 m day 1 and storage coefficient between 0 01 and 0 40 the results showed the existence of a strong vertical anisotropy of the aquifer the calibrated horizontal permeability is systematically higher than the vertical permeability 1000 1 the calibrated model was used to explore the recharge from or groundwater discharge to lake nasser at the seven transects for a 40 year period i e from 1965 to 2004 the analysis for the last 20 year period 1985 2004 revealed that recharge from lake nasser reduced by 37 compared to the estimates for the first 20 year period 1965 1984 in the period 1965 2004 seepage of lake nasser to the surrounding was estimated at 1 15 109 m3 year 1 this led to a significant rise of the groundwater table variance based sensitivity and uncertainty analysis on the edelman results were conducted applying quasi monte carlo sequences latin hypercube sampling the maximum standard deviation of the total uncertainty on the groundwater table was 0 88 m at toshka west of the lake the distance from the lake followed by the storage coefficient and hydraulic conductivity were identified as the most sensitive parameters copyright 2012 john wiley sons ltd

multiple flow regimes in the northern hemisphere winter part i methodology and hemispheric regimes abstract recurrent and persistent flow patterns are identified by examining multivariate probability density functions pdfs in the phase space of large scale atmospheric motions this idea is pursued systematically here in the hope of clarifying the extent to which intraseasonal variability can be described and understood in terms of multiple flow regimes bivariate pdfs of the northern hemisphere nh wintertime anomaly heights at 700 mb are examined in the present paper using a 37 year dataset the two dimensional phase plane is defined by the two leading empirical orthogonal functions eofs of the anomaly fields pdfs on this plane exhibit synoptically intriguing and statistically significant inhomogeneities on the periphery of the distribution it is shown that these inhomogeneities are due to the existence of persistent and recurrent anomaly patterns well known as dominant teleconnection patterns that is the pacific north american pna pattern its reverse and zonal and blocked phases of the

dynamics of floodplain island groundwater flow in the okavango delta botswana abstract surface water groundwater interactions play a crucial role in the hydrology and ecology of the okavango delta the hydrology of the delta is dominated by the annual arrival of a flood wave which is distributed over an number of branches subsequently the flood water feeds the phreatic aquifers underlying the delta islands in order to evaluate the seasonal and long term dynamics of the surface water groundwater interactions between the floodplains and the islands a network of piezometers located in various locations of the delta was monitored groundwater table fluctuations observed for up to 6 years were analysed and modelled using groundwater flow models the floodplain island groundwater flow is in general very dynamic and driven by island evaporation and transpiration a typical small to medium sized island width 500 m and at the perimeter of the flooded area is the influence of long term antecedent conditions apparent the knowledge gained during this study will be used for the improvement of the hydrological and hydro ecological model of the delta and can be useful for the description of floodplain dynamics in semi arid regions in general

thirty years of studies on badlands from physical to vegetational approaches a succinct review the scientific subjects addressed in the research into badlands since the publication of bryan and yair s book bryan r b and yair a editors 1982 badland geomorphology and piping geo books norwich 408 pp are briefly analysed with a steadily increasing number of papers per year attention to some aspects such as runoff generation piping and the role of lithology and soils varied whereas the percentage of studies on erosion rates increased steadily over time vegetation was not a subject of research in early papers as most of the papers dealing with vegetation were rather descriptive and published in local or limited diffusion media which contrasts with the present situation when about 40 of papers published in international journals about badlands address some aspect of vegetation however the growth in the attention paid to vegetation and erosion rates was not linked to any increase in papers dealing with badland reclamation badlands are now seen as a group of systems with some common features but diverse dynamics depending mainly on climatic and lithological drivers more attention should be paid in the future to investigating the evolution of these landforms over time mostly through modelling studies whereas emerging technologies foster detailed analyses that were not possible formerly although some badland areas determine on and off site environmental issues others are spots of landscape diversity that merit protection rather than reclamation

teleconnections in the geopotential height field during the northern hemisphere winter abstract contemporaneous correlations between geopotential heights on a given pressure surface at widely separated points on earth referred to as teleconnections in this paper are studied in an attempt to identify and document recurrent spatial patterns which might be indicative of standing oscillations in the planetary waves during the northern hemisphere winter with time scales on the order of a month or longer a review of existing literature on the subject reveals the existence of at least four such patterns the north atlantic and north pacific oscillations identified by walker and bliss 1932 a zonally symmetric seesaw between sea level pressures in polar and temperature latitudes first noted by lorenz 1951 and what we will refer to as the pacific north american pattern which has been known to operational long range forecasters in this country since the 1950 s a data set consisting of nmc monthly mean sea level pressure and 500 mb height analyses for a 15 year period is used as a basis fo

time lapse video observation of erosion processes on the black marls badlands in the southern alps france in order to clarify the erosion processes on a marly bare slope in the southern alps the erosion processes in a steep and erodible slope composed of the black marls formation were observed by a time lapse video camera the observations revealed that miniature debris flows mdfs occurred at the time of the rainfall runoff event in which the most severe erosion took place in the whole observation period of 3 months analysis of the camera images showed some characteristics of the mdfs and these are discussed in the context of real rainfall runoff phenomena observed at the outlet of a small experimental basin including the visually observed slope the following results were obtained 1 a rough estimation of the total amount of sediment discharge by the mdfs showed that it was not negligible quantitatively 2 the mdfs occurred only during the rising limb of the hydrograph during 6 minutes 3 based on this observation and a review of the literature in a very steep and highly erodible slope mdfs or similar phenomena might play an important role in the erosion and transport processes copyright 2008 john wiley and sons ltd

flood delineation in a large and complex alluvial valley lower panuco basin mexico determining the extent of flooding is an important role of the hydrological research community and provides a vital service to planners and engineers for large river systems located within distant settings it is practical to utilize a remote sensing approach this study combines a remote sensing and geomorphic approach to delineate the extent of a large hurricane generated flood event in the lower panuco basin 98 227 km2 the seventh largest river system draining into the gulf of mexico the lower panuco basin is located within the coastal plain of eastern mexico and has a complex alluvial valley data sources included a landsat 5tm and landsat 7etm scene and topographic and particle size data from fieldwork and laboratory analysis the landsat 5tm image was acquired after the peak of a large flood event in 1993 whereas the landsat 7etm scene was acquired during the dry season in 2000 the increasing number of days between flood crest and the date of flood image acquisition along the river valley provided the opportunity to examine several methods of flood delineation and to consider differences in floodplain geomorphology backswamp environments were easily delineated in flooded reaches within the panuco and tamuin valleys whereas in the moctezuma valley more sophisticated methods were required because of the greater time between image acquisition and flood peak and the complex floodplain topography this included principal component pc analysis and image classification within the floodplain residual holocene terraces complicated flood mapping classification of both images allowed consideration of the influence of permanent standing water although the flooded areas were greater in the lower reaches of the study area because this portion of the valley contained large floodplain lakes the amount of inundation was actually lower remote sensing offers the ability to examine large alluvial valleys in distant settings but does not imply that geomorphic criteria should be excluded indeed because of heterogeneous floodplain topography this study illustrates the importance of including field based geomorphic analysis so that the complexity of distinct floodplain environments are considered the findings from this study are significant because most remote sensing data obtained for the purpose of flood mapping will not coincide with the flood crest thus this study provides an appropriate method for mapping flood inundation in large and complex floodplain settings after flood crest recession

from gullies to mountain belts a review of sediment budgets at various scales this paper reviews the state of the art in the concept as well as in the application of sediment budgets in sedimentary research sediments are a product of mass dispersal at the earth surface and take part in global cycles sediment budgets aim at quantifying this mass transfer based on the principle of mass conservation and are the key to determine ancient fluxes of solid matter at the earth surface this involves fundamental questions about the interplay of uplift climate and denudation in mountain belts and transfer of sediments from the continents to the oceans as well as applied issues such as soil and gully erosion reservoir siltation and coastal protection first after introducing basic concepts relevant scales and methodologies the different components of quaternary routing systems from erosion in headwaters river systems glacial and paraglacial systems lakes deltas estuaries coasts shelves epicontinental seas and deep sea fans are discussed in terms of their sediment budget most suitable are sedimentologically closed or semi closed depositional environments e g alluvial fans lakes deltas and deep sea fans in a second step the dynamics of passive active and collisional tectonic settings and sediment budgets in related sedimentary basins are explored and new concepts of sediment portioning at large geodynamic scales are introduced ancient routing systems are more or less incomplete and may be intensively fragmented or destroyed in active tectonic settings in terms of sedimentary basin types rifts intracontinental and epicontinental settings are preferred objects of sediment budgets because of their persistence and relatively simple overall sedimentary architecture however closing basins such as foreland forearc retroarc piggy back and wedge top basins may provide excellent snapshots of orogenic sediment fluxes in a third step the large long lived routing systems of the amazon the ganges brahmaputra and the rhine are reviewed for each system estimates of either sediment volumes mass or sediment fluxes of continental and marine subsystems have been compiled in order to receive a complete routing in terms of mass conservation for specific time periods since the late glacial maximum as well as the cenozoic following lessons can be taken from these case studies i depositional centers and fluxes show strong shifts in space and time and call for caution when simply looking at subsystems ii the response times of these large systems are within the milankovich time interval thus lower than predicted from diffusion models iii cyclic routing of sediments in continental basins is much more dominated by climate human control than by eustacy and iv at long time scales ultimate sinks win over intermittent storage it is concluded from this review that the quantitative understanding of global sediment cycling over historic and geologic time and its response to allogenic forcing is still in its infancy and further research is needed towards a holistic view of sediment routing systems at various temporal and spatial scales and their coupling with global biogeochemical cycles this includes i to better determine response times of large routing systems by linking quaternary with cenozoic sediment budgets and continental with marine sub systems ii to combine advanced provenance techniques with sediment budgets in order to reconstruct ancient systems iii to study sediment partitioning at the basin scale iv to reconcile continental supply dominated sequence stratigraphy with the eustatic dominated marine concept and iv to account for non actualism of ancient systems with respect to their erosion and transport mode in particular during glaciations and pronounced arid intervals glacial and eolian sediment routing may cross over hydrologic boundaries of drainage basins thus challenging the principle of mass conservation

can bioengineering structures made of willow cuttings trap sediment in eroded marly gullies in a mediterranean mountainous climate abstract in the southern french alps high sediment yields from marly catchments cause socio economic and ecological problems downstream bioengineering structures made of willow cuttings could be used for efficient and sustainable sediment trapping in eroded gullies in order to decrease sediment yield at their outlets however little has been done to quantitatively assess the efficiency of such structures for trapping sediment or to improve their performance the objectives of this study were to analyze the ability of bioengineering structures to enhance vegetation development and sediment trapping in marly gullies in the southern french alps under a mountainous and mediterranean climate for five years after the restoration operations we monitored 101 bioengineering structures using willow salix cuttings including 55 brush layers on wooden sills bl and 46 brush layers with brush mats on wooden sills blm 1 2 m wide and 2 m long installed on the floors of eight experimental marly gullies the results showed that the ultimate survival of willow cuttings can be assessed after three years gully size and aspect appeared to be the most important factors influencing resprouting rates by avoiding south oriented gullies and those smaller than 1000 m 2 75 survival rates per structure may be achieved the results also showed that bl trapped 0 18 m 3 yr 1 of sediment per structure on average and blm 0 21 m 3 yr 1 but potential maximum values may reach 0 28 and 0 40 m 3 yr 1 over one year on bl and blm respectively therefore bioengineering structures made of willow cuttings can be used to trap significant quantities of sediment from the first year onwards and efficiently restore eroded marly gullies under a mediterranean mountainous climate it also provides design criteria to guide future restoration actions and future investigations in the southern french alps

badass gullies fluvio mass movement gully complexes in new zealand s east coast region and potential for remediation abstract this paper reviews gully erosion in the east coast region of new zealand s north island and conceptualises fluvio mass movement gully complexes as badass gully systems tectonic setting and lithological control with steep slopes and a climate influenced by tropical cyclones predispose hill country in the east coast region to gully erosion the clearance of indigenous forest since the late 1800s has dramatically increased catchment erosion and paved the way for development of large scale fluvio mass movement gully complexes these features are a composite of fluvial and mass movement processes they are conceptualised as badass by not conforming to any existing gully model and by generating disproportionate results in east coast catchment sediment cascades their remediation is discussed but their nature means that prevention is better than a cure

hydrological response of weathered clay shale slopes water infiltration monitoring with time lapse electrical resistivity tomography this work presents an attempt to monitor water infiltration and subsurface flow within a clay shale landslide using time lapse electrical resistivity tomography ert a rainfall experiment was carried out on a plot of 100 m2 at the laval landslide in the draix experimental catchments ore draix south french alps in order to characterize the spatial and temporal development of water circulation in the soil and to identify when steady state flow conditions are reached the experiment was conducted during 67 h with initial unsaturated conditions in the slope the apparent electrical resistivity values were inverted with a time lapse approach using several cross models the results indicate a significant decrease in resistivity 18 compared to the initial state in the rain plot downslope progression of negative resistivity anomalies is imaged suggesting that vertical and subsurface lateral flows have developed about 21 h after the start of the rain experiment a constant level of resistivity values is observed indicating that the hydrological system reached steady state flow conditions this observation is consistent with ground water level observations and chemical tracer analysis computed differences in time of steady state conditions highlight possible preferential flows near the landslide toe a hydrological concept of functioning of the slope is proposed and apparent saturated hydraulic conductivity ks of 1 7 10 4 m s 1 is computed from the steady state times this study demonstrates the potentiality of ert monitoring to monitor water infiltration in clay shale slopes and the high water transfer capacity of reworked clay shale material

cross frequency coupling skewness and blocking in the northern hemisphere winter circulation abstract variability in daily wintertime december february djf 500 hpa heights on low l 6 day 1 frequencies is examined using 40 yr ecmwf re analysis era 40 data leading eofs of l correspond to planetary scale teleconnection patterns those of m to retrograding eastward dispersing long waves oriented along great circle routes and those of h to baroclinic waves in the climatological mean storm tracks in the atlantic sector eof 1 of m appears to be embedded in eof 1 of l cross frequency coupling between l and m exhibits distinctive patterns in the atlantic sector the negative polarity of the north atlantic oscillation nao with above normal heights over greenland is associated with enhanced m variability over greenland an analogous relationship is observed in the pacific sector between an nao like pattern and the variance of m over alaska cross frequency coupling between l and h in both sectors is indicative of a reinforcement

statistical and analytical study of the propagation of flood induced groundwater rise in an alluvial aquifer the propagation of stage rises of the river danube in an adjoining alluvial aquifer kisalfold nw hungary has been studied by preparing a map which shows the lag times corresponding to maximum correlation values between the hydrographs of groundwater observation wells and the river stages as expected the lag times for the unconfined aquifer generally exceed those for the semi confined part the complex pattern suggests that other rivers in the area also play a role and that transmissivities and resistances of a cover layer are not sufficiently well known despite the presence of a relatively dense network of bore holes a systematic increase of the lag times with the distance from the river was noted at two sections nine flood events have been selected to study how well observed head rises could be predicted using equations for the calculation of the propagation of the head for phreatic and for confined conditions the results suggest that the water levels in the complex flood plain and the river bed conductance of silted up branches during the rise of the flood play an important role

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

a new framework for modeling sediment fining during transport with fragmentation and abrasion 1 a new framework for modeling sediment fining during transport is proposed the model is based on a physical description of both abrasion and fragmentation processes it attempts to describe and explain the changes in the grain size distribution of sediments during their transport in a water flow abrasion and fragmentation are modeled through the use of breakage frequency functions and daughter size distributions these functions are determined experimentally for the specific case study which is presented comparison between the predictions from the model and experimental data from the case study show that 1 both abrasion and fragmentation are involved in the degradation 2 fragmentation efficiency decreases during the experiment and 3 the shape of the pebbles provides feedback between abrasion and fragmentation this type of model is therefore appropriate for explaining degradation mechanisms which is promising for a future application to rivers

morphology and sedimentology of a complex debris flow in a clay shale basin coupling morphological sedimentological and rheological studies to numerical simulations is of primary interest in defining debris flow hazard on alluvial fans in particular numerical runout models must be carefully calibrated by morphological observations this is particularly true in clay shale basins where hillslopes can provide a large quantity of poorly sorted solid materials to the torrent and thus change both the mechanics of the debris flow and its runout distance in this context a study has been completed on the faucon stream southeastern french alps with the objectives of 1 defining morphological and sedimentological characteristics of torrential watersheds located in clay shales and 2 evaluating through a case study the scouring potential of debris flows affecting a clay shale basin morphological surveys grain size distributions and petrographic analyses of the debris flow deposits demonstrate the granular character of the flow during the first hectometre and its muddy character from there to its terminus on the debris fan these observations and laboratory tests suggest that the contributing areas along the channel have supplied the bulk of the flow material copyright 2005 john wiley sons ltd

tectonic forcing of evolution and holocene erosion rate of ravines in the marginal ganga plain india abstract understanding the processes of ravine formation and estimates of specific sediment yields ssy of these regions help in formulating mitigation policies significantly upto now in the ganga plain the work done on ravine formation erosion and ssy estimates has been speculative here utilizing i high resolution digital elevation models dems prepared from real time kinematic rtk survey and cartosat images of ravined zones and ii luminescence chronology we provide the first estimate of ssy from the ravines the results indicate that ssy in the marginal ganga plain mgp ravines may range between 600 100 t km 2 yr and 1600 200 t km 2 yr the correspondence between the orientations of fractures and that of first order ravine suggests that the ravine growth is genetically related to extensional stress regime of the peripheral forebulge further the clay sedimentology indicates that besides regional tectonics action of swelling clays may have accelerated development of the badlands the geomorphic relationship between the length of ravined catchments and incision in the trunk channels indicates that the river incision associated base level change is not playing an overarching role in the ravine formation in the mgp

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

landslides and climatic conditions in the barcelonnette and vars basins southern french alps france research into the climatic causes behind the triggering and reactivation of landslides has been carried out in two basins in the southern french alps where a great many landslides have occurred over more than a century correlations between landslides and climate are sometimes precise and closely related in time at other times imprecise and more distant the better known the type of landslide and the date of its occurrence the greater the correlation may appear be this as it may climate is never the sole cause this paper deals with the limits of the effects of climate

controls budgets and variability of riverine sediment fluxes to the gulf of lions nw mediterranean sea the present study investigates the spatio temporal variability of riverine sediment fluxes to the gulf of lions one of the most extensive shelf regions in the mediterranean sea small coastal rivers compete here with the rhone river nowadays the largest mediterranean river in terms of water discharge our scientific objectives were to investigate the major controls of riverine sediment yields sy in this area and to quantify the role of the small coastal rivers largely ignored in previous studies in the total sediment budgets another objective concerned the source identification of the rhone sediments with regard to the major tributary contributions and to test whether the sediment fluxes are in equilibrium in the basin for the calculation of representative long term fluxes we used a simplified rating curve approach sirca which could be validated by high resolution monitoring and existing literature data an overall of 13 drainage basins could be distinguished covering about 86 of the study area 6 coastal rivers the rhone river and 6 of its tributaries representative sy range from 19 to 151 t km 2 yr 1 in the investigated drainage basins despite their smaller basin areas and more torrential discharge regimes sy of the coastal rivers were generally lower compared to sy of the rhone river and its tributaries confrontation with the lithological morphological and hydroclimatic basin characteristics indicate that lithology exerts the dominant control on sy in the study region in particular the existence of erodible sedimentary rocks in the headwater regions yields high sy peak values of 135 and 151 t km 2 yr 1 were observed for the isere and durance tributaries of the rhone river where badlands exist the coastal rivers contribute on average only to slightly more than 5 of the long term sediment inputs to the gulf of lions during individual years however their contribution can strongly increase up to 27 in 2011 their contribution is generally important during late spring and autumn when flash floods are frequent up to 90 of the monthly sediment discharge summing the various tributary contributions of the rhone river produces a sediment budget that is close to the sediment export at the river mouth this indicates that at spatial scales the average sediment fluxes are equilibrated in the basin about 40 of the rhone sediments originate from the isere and durance tributaries however fully closure of the budgets requires high sy in the lowermost basin parts omitting in our calculations only a few years with exceptional flooding considerably reduce these values trend analyses show at the same time that the sediment fluxes from the saone and isere tributaries decreased during the study period at temporal scales sediment transport from upstream to downstream was therefore not in equilibrium and the remobilisation of older sediments from the downstream basin parts may have been important

impacts of topography on sediment discharge in loess plateau china abstract geomorphologic characteristics of a basin affect mass movement water and sediment transport the purpose of this study is to examine coupling relationship between topography and soil erosion in loess plateau during past 50 years 1960 2011 we firstly describe the distribution patterns of topographic characteristics and sediment discharge in specific river basins by using mathematical methods pca method linear regression and anova analysis and topographic variables we build a comprehensive index erosion topography index eti according to the research the following findings are obtained firstly average sediment discharge varies from 0 13 10 8 t to 7 56 10 8 t along the yellow river from the upper stream to down stream the sediment discharge of this region decreased 60 90 since the year of 1980 and decrease tendency is more obvious after the year 2000 compared to the period of 1980 2011 secondly topographic characteristics and the erosion topography index has similar distribution pattern thirdly there is no significant linear correlation between eti and all four sediment discharge variables average sediment total sediment sediment of 1980 2011 and sediment of 2000 2011 but there are significant positive linear correlations p p 0 035 than other variables and the gradient coefficient of them is higher k 0 667 than other variables too except the topographic characteristics the vegetation coverage and human activities should be other factors that can influence the variations of sediment discharge in loss plateau

influence of vegetation distribution on sediment yield in forested marly gullies abstract the cover provided by forest vegetation makes it possible to fight erosion efficiently furthermore vegetation barriers can also play a major role by trapping eroded sediments and thus vegetation located downslope of a gully can be important the objective of this study is to highlight the role of vegetation distribution in a marly gully in reducing sediment loss at the outlet to do this sediment yield in gullies with similar geological and geomorphological components but with different vegetation cover and distribution was studied for 2 years sediment traps installed at gully outlets permitted the distinction of active gullies from inactive ones the results show that gully activity is not correlated with the percentage of total vegetation cover but with the percentage of cover of low vegetation in the gully floor this is due to sediment trapping processes and highlights the importance of the spatial distribution of forest vegetation in reducing sediment yield at the gully outlet thus gullies with similar total vegetation cover can have very different activities and inactive gullies exist that are only partially covered with vegetation inactive gullies with as low as 33 vegetation cover occur where vegetation is mainly present in the gully floor the results also show that above 50 cover of low vegetation in the gully floor as a percentage of the gully floor surface gullies are generally inactive

annual fossil organic carbon delivery due to mechanical and chemical weathering of marly badlands areas a key issue in the study of the carbon cycle is constraining the stocks and fluxes in and between c reservoirs among these the role and importance of fossil organic carbon foc release by weathering of outcropping sedimentary rocks on continental surfaces is still debated and remains poorly constrained our work focuses on foc fluxes due to chemical and mechanical weathering of marls in two experimental watersheds with typical badlands geomorphology draix watersheds laval and moulin alpes de haute provence france organic matter from bedrock soil litter and riverine particles are characterized by rock eval 6 pyrolysis foc fluxes due to mechanical weathering are then estimated by monitoring the annual particulate solid exports at the outlets of the watersheds 1985 2005 period foc fluxes from chemical weathering were calculated using ca2 concentrations in dissolved loads year 2002 to assess the amount of foc released by the dissolution of the carbonate matrix results show that foc delivery is mainly driven by mechanical weathering with a yield ranging from 30 to 59 t km 2 yr 1 in the moulin 0 08 km2 and laval 0 86 km2 catchments respectively 1985 2005 average the release of foc attributed to chemical weathering was 2 2 to 4 2 t km 2 for the year 2002 these high foc fluxes from badlands are similar to those observed in tectonically active mountain catchments at a regional scale badland outcropping within the durance watershed does not exceed 0 25 in area of the rhone catchment but could annually deliver 12 000 t yr 1 of foc this flux could correspond to 27 of the total particulate organic carbon poc load exported by the rhone river to the mediterranean sea at a global scale our findings suggest that erosion of badlands may contribute significantly to the transfer of foc from continental surfaces to depositional environments copyright 2012 john wiley sons ltd

erosion quantification in the small marly experimental catchments of draix alpes de haute provence france calibration of the etc rainfall runoff erosion model abstract erosion rates measured for 15 years in the small ranging from 0 13 ha to nearly 1 km2 and steep 30 75 mountainous marly basins of draix south alps france are over 100 tons ha year in a badland area devoid of vegetation in a similar basin reforested at the end of the 19th century the sediment yield is considerably reduced less than 3 tons ha year the analysis of the sediment yield of these torrents reveals the importance of the erosion processes on slopes at the scale of the elementary gully and the influence of deposition transport and scouring processes as soon as the channel network of the basin is developed these processes were modelled by a hydrosedimentologic model developed by cemagref for flood torrent erosion and called etc etc is an integrated spatialized and global model working at the event scale the rainfall runoff component and the solid transport component which involves scouring deposition and armouring are well developed on the other hand the erosion component is not yet a physically based model as the knowledge on the elementary processes is not enough quantitative the etc model was used on a badland basin of 86 ha in area the laval and has shown its ability to simulate both water and sediment flows in mountainous and steep basins the erosion modelling highlighted the need for a better representation of the slope processes and for more information on the storing of sediments in the channel network observations carried out on the influence of the vegetation cover patterns and the links between slopes and channels should be taken into account to improve the model

the pacific center of action of the northern hemisphere annular mode real or artifact the leading empirical orthogonal function eof of the sea level pressure slp field referred to as the arctic oscillation ao or northern hemisphere annular mode nam consists of a dipole between the polar cap region and the surrounding zonal ring centered along 458n embedded within the outer ring are centers of action over the euro atlantic and pacific sectors in which slp fluctuates in phase that the observed slp fluctuations at these two centers of action are virtually uncorrelated raises the question of whether the pacific center in the annular mode could be an artifact of eof analysis it is argued that sea level pressure fluctuations at the pacific and euro atlantic centers of action of the ao nam would be more strongly correlated were it not for the fact that slp variability over the north pacific is dominated by a pattern in which fluctuations over the north atlantic and north pacific are inversely related evidence of the coexistence of such a pattern which resembles an augmented version of the pacific north american pattern is presented

enso like interdecadal variability 1900 93 a number of recent studies have reported an enso like eof mode in the global sea surface temperature sst field whose time variability is marked by an abrupt change toward a warmer tropical eastern pacific and a colder extratropical central north pacific in 1976 77 the present study compares this pattern with the structure of the interannual variability associated with the enso cycle and documents its time history back to 1900 the analysis is primarily based on the leading eofs of the sst anomaly and anomaly deviation fields in various domains and the associated expansion coefficient or principal component time series which are used to construct global regression maps of sst sea level pressure slp and a number of related variables the use of anomaly deviations i e departures of local sst anomalies from the concurrent global mean sst anomaly reduces the influence of global mean sst trends upon the structure of the eofs and their expansion coefficient time series an important auxiliary time series used in this study is a southern oscillation index based on marine surface observations by means of several different analysis techniques the time variability of the leading eof of the global sst field is separated into two components one identified with the enso cycle related variability on the interannual timescale and the other a linearly independent residual comprising all the interdecadal variability in the record the two components exhibit rather similar spatial signatures in the global sst slp and wind stress fields the sst signature in the residual variability is less equatorially confined in the eastern pacific and it is relatively more prominent over the extratropical north pacific the corresponding slp signature is also stronger over the extratropical north pacific and its counterpart in the cold season 500 mb height field more closely resembles the pna pattern the amplitude time series of the enso like pattern in the residual variability reflects the above mentioned shift in 1976 77 as well as a number of other prominent features including a shift of opposite polarity during the 1940s

large scale rainfall simulation to investigate infiltration processes in a small landslide under dry initial conditions the draix hillslope experiment few studies exist on infiltration processes in badlands although infiltration and subsurface lateral flows are known to contribute to soil erosion and to control slope instability our investigation was carried out in a 100 m plot located in a 0 5 ha landslide in black marls south east france an artificial sprinkling was performed with an intensity of 10 mm h 1 during 66 4 h interrupted with 8 4 h breaks kbr and kcl were used as tracers a pseudo steady state was reached after 25 35 h and 250 350 mm of rainfall the runoff coefficient was 40 ratio total runoff volume total sprinkling water amount pre event water pe contributed to the groundwater recharge at the very beginning of the experiment but pe contribution dropped steadily while the soil was saturating after around 200 mm of cumulative rainfall pe contribution started to rise steeply before reaching a nearly constant value this original mechanism implies an efficient transfer process of pe it was assumed from the description of the material structure and from hydrological evidences that pe was mainly drained from a structure porosity made of marl s flaked nature total pe contributions ranged from 25 to 79 pe contribution was over 50 in 2 3 of the observation wells over the recession phase release of pe occurred from the drainage of texture porosity the study showed that at the plot scale infiltration processes proved to be well organized despite the high heterogeneity and anisotropy of the material it was possible to propose a general conceptual model explaining the hydrological processes over time and area the peculiar structure of regolith originating from black marl is preserved over a large part of the weathering time so that the material structure type orientation of grains small large pores remains a first order control of water flow generation in black marl soils copyright 2012 john wiley sons ltd

assessment of intermediate fine sediment storage in a braided river reach southern french prealps this paper presents a field investigation on river channel storage of fine sediments in an unglaciated braided river the bes river located in a mountainous region in the southern french prealps braided rivers transport a very large quantity of bedload and suspended sediment load because they are generally located in the vicinity of highly erosive hillslopes consequently these rivers play an important role because they supply and control the sediment load of the entire downstream fluvial network field measurements and aerial photograph analyses were considered together to evaluate the variability of fine sediment quantity stored in a 2 5 km long river reach this study found very large quantities of fine sediment stored in this reach 1100 t per unit depth 1 dm given that this reach accounts for 17 of the braided channel surface area of the river basin the quantities of fine sediment stored in the river network were found to be approximately 80 of the mean annual suspended sediment yields ssys 66 200 t year 1 comparable to the ssys at the flood event scale from 1000 t to 12 000 t depending on the flood event magnitude these results could explain the clockwise hysteretic relationships between suspended sediment concentrations and discharges for 80 of floods this pattern is associated with the rapid availability of the fine sediments stored in the river channel this study shows the need to focus on not only the mechanisms of fine sediment production from hillslope erosion but also the spatiotemporal dynamics of fine sediment transfer in braided rivers copyright 2010 john wiley sons ltd

occurrence of fossil organic matter in modern environments optical geochemical and isotopic evidence abstract this study relates to the input and fate of fossil organic matter fom in the modern environment and focuses on two experimental watersheds overlying jurassic marls le laval and le brusquet 1 km2 in area located near digne alpes de haute provence france considering that fom delivery is mainly a result of different processes affecting sedimentary rocks bio chemical and mechanical weathering samples from different pools were collected bedrocks weathering profiles soils and riverine particles the samples were examined using complementary techniques optical palynofacies methods geochemical rock eval 6 pyrolysis c n ratio molecular gas chromatography mass spectrometry and isotopic stable c isotopic composition as a result fom markers were identified and tracked through the different pools the results highlight the contribution of fom which can be found in all the studied pools transfer of fom between bedrocks weathering profiles governed mainly by chemical weathering and bedrocks riverine particles governed mainly by mechanical weathering reveals any qualitative change weathering profiles soils transition governed by bio chemical weathering is characterized by alteration of the fom which is difficult to describe because fossil material is mixed with recent organic matter rom despite this latter point the study provides evidence for a relative resistance of fom to weathering processes and points to its contribution to the modern geosystem and the c cycle

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

from experimental plots to experimental landscapes topography erosion and deposition in sub humid badlands from structure from motion photogrammetry in the last decade advances in surveying technology have opened up the possibility of representing topography and monitoring surface changes over experimental plots 10 m2 in high resolution 103 points m 1 yet the representativeness of these small plots is limited with structure from motion sfm and multi view stereo mvs techniques now becoming part of the geomorphologist s toolkit there is potential to expand further the scale at which we characterise topography and monitor geomorphic change morphometrically moving beyond previous plot scale work using terrestrial laser scanning tls surveys this paper validates robustly a number of sfm mvs surveys against total station and extensive tls data at three nested scales plots 30 m2 within a small catchment 4710 m2 within an eroding marl badland landscape 1 km2 sfm surveys from a number of platforms are evaluated based on i topography ii sub grid roughness and iii change detection capabilities at an annual scale oblique ground based images can provide a high quality surface equivalent to tls at the plot scale but become unreliable over larger areas of complex terrain degradation of surface quality with range is observed clearly for sfm models derived from aerial imagery recently modelled doming effects from the use of vertical imagery are proven empirically as a piloted gyrocopter survey at 50m altitude with convergent off nadir imagery provided higher quality data than an unmanned aerial vehicle uav flying at the same height and collecting vertical imagery for soil erosion monitoring sfm can provide data comparable with tls only from small survey ranges 5 m and is best limited to survey ranges 10 20 m synthesis of these results with existing validation studies shows a clear degradation of root mean squared error rmse with survey range with a median ratio between rmse and survey range of 1 639 and highlights the effect of the validation method e g point cloud or raster based on the estimated quality

erosion and sediment transport on steep marly hillslopes draix haute provence france an experimental field study abstract despite a thin regolith layer measured sediment yields indicate denudation rates of more than 10 to 20 mm yr 1 on strongly denuded slopes in black marl terres noires near draix alpes de haute provence overland flow and rainfall simulation experiments were conducted on three slopes in the draix erosional research basin to determine the nature and intensity of hillslope erosion processes the experiments showed that during a single storm sediment transport includes water solid mixtures with a wide range of concentrations from highly charged rill flow up to 400 g l 1 to hyperconcentrated flow up to 800 g l 1 to debris flows up to 1400 g l 1 miniature debris flows mdfs strongly controlled sediment transport as long as the sediment store was not depleted slope surfaces were completely reworked in the winter and the regolith layer was rebuilt temperature records from nine recent winter periods indicate that conditions are favourable for soil frost processes

how mudrock and soil physical properties influence badland formation at vallcebre pre pyrenees ne spain abstract soils regoliths and their parent materials were investigated in relation to the development of badlands in the pre pyrenees in ne spain on late cretaceous mudrocks under a mountain mediterranean climate whilst all the soils in the area which are developed on mudrocks show a good structure and support a dense plant cover the bare parent materials slake very rapidly giving rise to badlands characterized by high erosion rates several physical chemical mineralogical and micromorphological properties of soils regoliths and related parent materials were analyzed in order to explain their different susceptibility to erosion and to determine which of all these properties are better related to such erosive behaviour only micromorphological and porosity properties were able to explain the erosion susceptibility whilst mineralogical chemical and physico chemical specific surface area properties were not among the aggregate stability tests performed to estimate the relationships of soil components with the susceptibility to erosion the emerson test for macroaggregate evaluation was particularly well suited although no good correlation was found between the emerson test classes and organic matter content we observed that the degree of slaking in organic rich horizons was always lower than in subsurface horizons and regoliths consequently as far as organic rich aggregates are present in the soil surface the influence of water in producing slaking swelling and then erosion will be minimum however when regoliths and rocks are uncovered the influence of water in these particular materials through freeze drying and swell shrinking will give rise to mudrock desintegration leading to accelerated erosion

transient groundwater flow in an aquifer aquitard system in response to water level changes in rivers or canals abstract previous authors have studied unsteady flow in aquifer aquitard systems with negligible storactivity in the confined aquifer layer formulae have been developed for groundwater level in the aquifer or aquitard and no adequate tables and graphs have been provided in this paper solutions for transient flow in an aquifer aquitard system that consider storativity in a confined layer in response to both abrupt and uniform water level changes as well as steady seepage rate from rivers or canals are developed analytical formulae for groundwater levels both in the aquifer and aquitard and for seepage rate and total amount of water percolated from rivers have been derived to facilitate computation graphs for the special functions involved in the proposed equations have been prepared

effectiveness of vegetation barriers for marly sediment trapping vegetation barriers can be effective in trapping eroded sediment but little knowledge exists on the characteristics of vegetation barriers efficient in trapping all sediments from an eroded zone upslope the objective of this study is to quantify the effectiveness of vegetation barriers for marly sediment trapping relationships between eroded zones and vegetation barriers composed of low vegetation that is to say herbaceous and under shrub layers located downslope and sufficient to stop all the sediments eroded above have been studied in the brusquet experimental marly catchment in the french southern alps 40 plots with surface areas less than 500 m were studied the eroded zones and the vegetation barriers were characterised by their surface areas between which an average linear relationship exists results also showed that for a marly plot with a given surface area a downslope vegetation barrier covering only 20 of this plot can be sufficient to trap all the sediments eroded above it

soil surface characteristics influence on infiltration in black marls application to the super sauze earthflow southern alps france soil surface characteristics sscs have a strong influence on the infiltration properties at the soil surface they can explain spatial variations in the infiltration processes observed under natural rainfall for relatively little differentiated material and can help us to understand the surface and subsurface hydrology of landslides representative of some of black marls landscapes of the french southern alps this paper presents the results of investigations into the influence of sscs using careful morphological description in situ tension disc infiltrometry and statistical analysis hierarchical ascending classification and stepwise discriminant analysis the site studied is the super sauze earthflow the selected infiltration and runoff variables were described for 233 microplots chosen all over the earthflow the results show that an approach based on a description of relevant variables influencing water infiltration can validate a typology based on expert knowledge hydraulic conductivity at saturation was measured on 36 undisturbed soil cores and at low negative pressure heads on 83 microplots the dispersion exceeds three orders of magnitude at each pressure head a statistical analysis of the data set obtained by describing selected variables showed the relevance of the black marl descriptors when defining types of ssc that enable us to distinguish significant hydrodynamical behaviour this leads us to suggest a distribution of hydraulic conductivity curves near saturation for each ssc type which can be used as a key to distribute local hydraulic conductivity values adapted to black marl hillslopes as well as the types of ssc at a microplot scale leading to types of hydrodynamic properties the typology of combinations of sscs at a coarser scale should lead to types of hydrological response and to identification of hydrological and geomorphological response units copyright 2003 john wiley sons ltd

climate scale modelling of suspended sediment load in an alpine catchment debris flow rio cordon northeastern italy abstract pulsing storms and prolonged rainfall can drive hydrological damaging events in mountain regions with soil erosion and debris flow in river catchments the paper presents a parsimonious model for estimating climate forcing on sediment loads in an alpine catchment rio cordon northeastern italian alps hydroclimatic forcing was interpreted by the novel clismssl climate scale modelling of suspended sediment load model to estimate annual sediment loads we used annual data on suspended solid loads monitored at an experimental station from 1987 to 2001 and on monthly precipitation data the quality of sediment load data was critically examined and one outlying year was identified and removed from further analyses this outlier revealed that our model underestimates exceptionally high sediment loads in years characterized by a severe flood event for all other years the clismssl performed well with a determination coefficient r2 equal to 0 67 and a mean absolute error mae of 129 mg y 1 the calibrated model for the period 1986 2010 was used to reconstruct sediment loads in the river catchment for historical times when detailed precipitation records are not available for the period 1810 2010 the model results indicate that the past centuries have been characterized by large interannual to interdecadal fluctuations in the conditions affecting sediment loads this paper argues that climate induced erosion processes in alpine areas and their impact on environment should be given more attention in discussions about climate driven strategies future work should focus on delineating the extents of these findings e g at other catchments of the european alpine belt as well as investigating the dynamics for the formation of sediment loads

assessment of sidewall erosion in large gullies using multi temporal dems and logistic regression analysis although in the last decades gully erosion has been a thriving research field few studies have specifically addressed the contribution and location of sidewall erosion processes in gullies in this paper sidewall erosion in some large gullies in a mediterranean area anoia penedes ne spain is mapped and assessed for two time intervals 1975 1995 and 1995 2002 using detailed digital elevation models derived from aerial photographs at a scale of 1 5000 to 1 7000 logistic regression analysis is applied to compute the probability of occurrence of gully sidewall erosion from terrain variables the results confirm the complex nature of sidewall processes whose intensity is most probably related to rainfall characteristics prolonged wet soil conditions in the period 1995 2002 together with the large and high intensity rainfall of an extreme event occurred on 10th june 2000 help to explain the different sediment production rates 16 0 4 mg ha 1 year 1 in 1975 1995 and 83 6 3 mg ha 1 year 1 in 1995 2002 the logistic regression analysis revealed that gully wall slope angle was the main factor controlling gully sidewall failure in gully walls with high slope angles tension crack development is the main process promoting wall collapse the application of the logistic regression model showed a high overall accuracy 87 but over 50 of commission and omission errors for the class of interest sidewall erosion in agreement with the variance explained by the model

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

bedload monitoring under conditions of ultra high suspended sediment concentrations the bedload response of the moulin ravine a small alluvial system draining a very active mediterranean badlands landscape entrenched into jurassic black marls of the southern french prealps has been investigated using an automatic reid bedload slot sampler this site is known for its exceptional sediment transport conditions thanks to a long term monitoring program that started in the late 1980s revealing a mean annual bedload yield of 2810 t km 2 yr 1 and suspended sediment concentrations sscs during flow events commonly reaching 100 g l 1 with the deployment of the slot sampler it has been possible to record instantaneous bedload fluxes during 10 s time increments and to investigate bedload response under flow conditions with ultra high sscs bedload records cover 4 flashy summer flow events induced by heavy convective storms including a 20 yr return period event due to the very high ssc conditions these events challenge bedload monitoring even if slot sampling has been recognized as insensitive to fine sediments silts and clays it has never been tested in such exceptional muddy flow conditions the bedload slot sampler performed well in such conditions a flow invariant proportion of fines 15 20 was captured in the slot sampler during flows this proportion is equivalent to its content in the active bedload layer during summer flows suggesting that fines enter the slot embedded with coarse particles instantaneous bedload fluxes recorded in the moulin are amongst the highest hitherto reported values worldwide providing evidence of the exceptional sediment transport conditions of marly alpine badlands the dimensionless entrainment threshold is one order of magnitude higher than commonly reported for gravel bed rivers likely reflecting the cohesion effect of fines intruded in the channel surface and subsurface

high resolution quantitative reconstruction of erosion rates based on anatomical changes in exposed roots at draix alpes de haute provence critical review of existing approaches and independent quality control of results extensive areas of french alps are underlain by jurassic black marls wherever these terres noires crop out they become subject to intense erosion causing major sedimentation in regional reservoirs and river systems in the badlands near draix alpes de haute provence france measured sediment rates were obtained at the plot scale by surface elevation change based methods and at the catchment scale by monitoring sedimentation in dams in this study we use a dendrogeomorphic approach based on anatomical changes in exposed roots of pinus sylvestris l to accurately quantify continuous denudation rates a total of 123 cross sections 75 from buried and 48 from exposed roots of 23 trees were sampled in the moulin basin the size and position of roots at the time of exposure was determined via anatomical variations in the annual growth rings of roots in cross sections of buried roots a sharp reduction of earlywood tracheid lumen area a growth signature which has traditionally been used to determine the moment of root denudation was observed as soon as erosion reduced soil cover to 3 cm as a consequence estimates of eroded soil thickness had to be adjusted to take account of this bias bias adjusted averaged medium term erosion rates derived from exposed roots vary between 6 and 7 mm y 1 at moulin basin depending on the importance accorded to the uplift of roots after exposure values are significantly correlated to slope angle and match with erosion rates derived from monitored iron stakes 5 7 mm y 1 or measurements of sediment yield in retention dams 4 7 mm y 1 at the outlet of the moulin basin besides demonstrating that the interpretation of anatomical signatures in tree roots to erosion have to be revised this paper also shows that dendrogeomorphic analyses of roots are indeed a powerful tool for the quantification of minimal rates of soil erosion in environments where measurements of past activity are not available

the arctic oscillation signature in the wintertime geopotential height and temperature fields the leading empirical orthogonal function of the wintertime sea level pressure field is more strongly coupled to surface air temperature fluctuations over the eurasian continent than the north atlantic oscillation nao it resembles the nao in many respects but its primary center of action covers more of the arctic giving it a more zonally symmetric appearance coupled to strong fluctuations at the 50 hpa level on the intraseasonal interannual and interdecadal time scales this arctic oscillation ao can be interpreted as the surface signature of modulations in the strength of the polar vortex aloft it is proposed that the zonally asymmetric surface air temperature and mid tropospheric circulation anomalies observed in association with the ao may be secondary baroclinic features induced by the land sea contrasts the same modal structure is mirrored in the pronounced trends in winter and springtime surface air temperature sea level pressure and 50 hpa height over the past 30 years parts of eurasia have warmed by as much as several k sea level pressure over parts of the arctic has fallen by 4 hpa and the core of the lower stratospheric polar vortex has cooled by several k these trends can be interpreted as the development of a systematic bias in one of the atmosphere s dominant naturally occurring modes of variability

hydrological behaviour of sub mediterranean alpine headwater streams in a badlands environment summary investigations of flash floods generation processes are very few compared with studies in humid areas the rapidity and intensity of these processes make difficult any data acquisition on the field the present study aims to improve our knowledge on these environments by using the facilities of the draix erbs southern french alps where well documented black marls show a typical badlands morphology with v shaped gullies time varying components of total flow and flow sources have been investigated from a long term isotopic and hydrochemical survey of rainwaters overland waters soil waters and streamwaters we present in greater detail two flood events which occurred in three adjacent basins and had contrasting antecedent soil moisture conditions isotopic data were used to apply time based hydrograph separations due to the very short transfer time of waters convolution of the rainfall isotopic signal with a two parameter transfer function dispersive transfer function proved the best way to assess the event isotopic concentration end members mixing analysis emma has been carried out using non reactive chemical species to get source areas of runoff new water participation by direct surface transfer was the main mechanism at the peak discharge this contribution was found to dominate irrespective of whether the antecedent soil moisture was dry or wet nevertheless up to 20 of subsurface water has been observed at peak discharge for dry pre event conditions during the flow recession phases this subsurface water contribution was greater for wet antecedent conditions in dry initial conditions subsurface water was mostly new water whereas in wet conditions pre event water could contribute to the flow a deep groundwater reservoir may take part in the pre event component in the larger basin but in the smaller basins pre event water was mostly made of short residence time water from previous rainfall events originating from sporadic highly transmissive shallow hillslope reservoirs loose detrital cover and upper regolith differences regarding the hierarchy of the processes were not found to be simply proportional to the basins area nor were they clearly related to the mean slope gradients or to the percentage of vegetal cover it is suggested that controls on streamflow generation occur at local scale and consist in the spatial organisation and the gradual accumulation downwards of first order basins with their respective physical specificities mostly orientation and slope gradient

controls of groundwater floodwave propagation in a gravelly floodplain summary interactions between surface water and groundwater can occur over a wide range of spatial and temporal scales within a high hydraulic conductivity gravelly floodplain in this research dynamics of river groundwater interactions in the floodplain of the matane river eastern canada are described on a flood event basis eleven piezometers equipped with pressure sensors were installed to monitor river stage and groundwater levels at a 15 min interval during the summer and fall of 2011 results suggest that the alluvial aquifer of the matane valley is hydraulically connected and primarily controlled by river stage fluctuations flood duration and magnitude the largest flood event recorded affected local groundwater flow orientation by generating an inversion of the hydraulic gradient for 16 h piezometric data show the propagation of a well defined groundwater floodwave for every flood recorded as well as for discharges below bankfull 0 5 qbf a wave propagated through the entire floodplain 250 m for each measured flood while its amplitude and velocity were highly dependent on hydroclimatic conditions the groundwater floodwave which is interpreted as a dynamic wave propagated through the floodplain at 2 3 orders of magnitude faster than groundwater flux velocities it was found that groundwater exfiltration can occur in areas distant from the channel even at stream discharges that are well below bankfull this study supports the idea that a river flood has a much larger effect in time and space than what is occurring within the channel

assessment of soil particle erodibility and sediment trapping using check dams in small semi arid catchments check dams can be used as a source of information for studies on sediment characteristics and soil particle erodibility in this study sediment yield and grain size distribution gsd were measured in twenty small catchments draining into a rock check dam in nw iran for different runoffs during 2010 2011 significant correlations were found between sediment yield and slope steepness vegetation cover and soil erodibility factor k of the catchments the erodibility of soil particles was determined using the comparison of gsd between sediment and original soil clay was the most erodible soil particle which showed 2 05 times more percentage in sediment than the original soil the erodibility of soil particles were strongly affected by the rainfall erosivity ei30 check dams showed more effectiveness in trapping coarse particles sand and gravel the effectiveness of check dams in trapping coarse particles enhanced with increase in the remaining capacity of check dams

sediment residence time in alluvial storage of black marl badlands abstract the aim of this study is to estimate the sediment residence time in the stream network of two small headwater catchments laval and moulin characterized by a badlands landscape entrenched into jurassic black marls of the southern french prealps the method is based on an intensive field survey of the alluvial storage along the main stream reaches from which a scaling law between the average thickness of alluvial deposits and their width was established in order to predict the volume of alluvial deposits in the entire stream network to complete this approach bedload sediment yield monitored over the last 30 years with topographic surveying of sediment retention basins are used the assessment of sediment residence time is performed according to a steady state assumption validated by the long term dynamic equilibrium of bedload sediment yields the results highlighted very close values of residence time between the catchments around 3 years despite a one order of magnitude difference in drainage area it is shown that the rate of increase of alluvial storage with drainage area is the same as for sediment yield this is likely attributed to the high degree of confinement of the stream network which prevent the formation of a floodplain or large internal alluvial fans implications of these results for the prediction of the effects of bioengineering works in controlling erosion are discussed

geological and geotechnical properties of the terres noires in southeastern france weathering erosion solid transport and instability abstract the geological formation known as the terres noires covers large areas of southeastern france between the rhone valley and the pre alpine hills this formation consists mainly of dark marls of the basal upper jurassic these marls are very susceptibility to weathering and are particularly prone to erosion resulting in high solid transport this paper attempts to quantify this transport in experimental catchment areas and shows that a forest cover can play a major role in preventing this type of phenomenon weathering of this formation may also lead to gravity instabilities in fresh marl although this is rare and much more frequently in the surficial weathered material

application of physical modelling of debris flow triggering to field conditions limitations posed by boundary conditions abstract debris flows are often triggered by hortonian overland flow during high intensity rainstorms data derived from debris flow trigger zones in the southern french alps were fed into a physical model of debris flow triggering based on takahashi using a monte carlo approach with 1000 runs the results show a wide distribution of safety factor values indicating that physical modelling based on actual field measurements may not always be practical as all safety factor values obtained are well below 1 even though debris flows only occur during very high intensity rainstorms the model used must be inappropriate apparently the composition of the overland flow plays an important role during high intensity rainstorms it usually has a very high sediment content and contains stones this prevents it from flowing through the pores of coarse debris accumulations in the central gully of a trigger zone it will rather run over the debris this situation is more stable than with the fluid flowing through the pores the behaviour switch of the fluid above a certain sediment and stone content thus drastically changes the triggering conditions for debris flows and it is concluded that debris flow triggering in the area requires the occurrence of both overland flow and landsliding

short and long term studies of sediment dynamics in a small humid mountain mediterranean basin with badlands abstract badland landscapes are the main sediment sources in the vallcebre area eastern pyrenees catalonia spain short term studies up to 3 years long carried out between 1980 and 1994 were used to estimate the rates of both denudation on bare surfaces and sediment production at the plot scale to analyse the seasonal dynamics of bedrock weathering and regolith behaviour and to study the relationships between geomorphic activity and herbaceous plant colonisation since 1990 stream flow and suspended sediment loads have been monitored using three gauging stations equipped with infrared backscattering turbidimeters ultra sonic beam attenuation solids sensors and automatic water samplers the combination of the two different approaches has been useful for a better perception of the dynamics of the badland systems and to assess the long term contribution of these areas to the basin sediment loads badland erosion at the event scale for a period of 15 years was simulated with the kineros2 model and allowed the long term comparison between badland erosion and sediment yield at the small basin scale badlands are the main source of sediment in the basin for most of the events but infrequent runoff events cause the removal of sediment stores and the activation of other sediment sources the analysis of the uncertainty of sediment yield measurements for a range of record durations demonstrated that long records are needed for obtaining acceptable results due to the high interannual variability relatively low cost short term geomorphic observations may provide information useful for assessing the long term sediment production in these basins with badland areas only if the observations are used to implement a model able to simulate long term observations

synoptic analysis of cold air outbreaks over the california central valley abstracthow does extreme cold air reach the california central valley ccv and most of the u s west coast this question is answered using composite patterns for the 10 coldest cold air outbreaks caos to reach the ccv during 1979 2013 while unusually cold air over california occurs in all events by design how it arrives there is complicated and varies the only other feature present in all events for several days prior to cao onset is unusually strong surface high pressure in and south of the gulf of alaska this high has low level cold air on its west side and a deep layer of cold air moving southward on its east side cold air aloft flows parallel to the north american west coast and sinks as it approaches the ccv farther west warm advection builds a ridge aloft the large scale meteorological pattern lsmp is equivalent barotropic the lsmp s ridge over alaska trough near california and ridge over the southeastern united states appear in all cases by onset and resemble the pacific north amer

sediment budget quantification of a sub alpine river catchment since the end of the last glaciation changes in sediment budget and quantification of sediment fluxes of a small 5 3 km2 mediterranean sub alpine river catchment charanc catchment southern french alps 44 30 44n 5 51 55e are estimated for the last 20 000 years using a gis based approach and 3d palaeotopographic reconstructions following field surveys a high resolution morphometric map was established ten 14c ages of sub fossil trees and charcoal beds were compiled all datasets were integrated into a geographic information system we computed three palaeosurfaces by masking the digital elevation model of the current topography and calculated the sediment budget of the catchment estimations of specific hillslope erosion sedimentation and export rates highlight the evolution of the catchment and its sensitivity to variations in the ratio of sediment load to stream discharge between 20 000 and 14 500 cal bp sediment that was eroded 37 million m3 within the charanc catchment was entirely exported a change to a sedimentation regime commenced at around 14 500 cal bp between 9000 cal bp and 7000 cal bp footslopes were buried by fan shaped deposits at a rate of 6700 m3 yr since 7000 cal bp the overall morphogenetic regime has been one of vertical incision 73 of the material eroded over the last 14 500 years 14 million m3 was stored in fan shaped deposits at the present time 46 of this volume 6 million m3 is still stored in the catchment 8 million m3 of sediments have thus been exported out of the charanc catchment since 14 500 cal bp annual specific erosion rates on marly slopes are estimated at 1 98 to 111 t ha yr for the period 20 000 14 500 cal bp which is comparable to present rates measured on denudated marls in the southern french alps under a probably climate driven erosion regime and 2 17 to 20 t ha yr since 14 500 cal bp a reduction in erosion rate that may have been favoured by a more extensively wooded landscape

stream aquifer interactions at great sand dunes national monument colorado influences on interdunal wetland disappearance abstract between 1937 and 1995 a complex of more than 100 interdunal wetlands disappeared from great sand dunes national monument colorado we investigated three hypotheses that could explain wetland disappearance 1 dune movement during a severe drought in the 1950s buried the wetlands 2 agriculture related ground water pumping lowered the regional water table and 3 changes in local hydrologic processes led to wetland loss we used regional stream flow records ground water level measurements natural stable isotope analyses soil stratigraphy buried seed banks and ground water modeling to address these hypotheses hydrologic data and stable isotope analyses illustrated the interaction between sand creek a nearby stream and the unconfined aquifer in the area where wetlands occurred when the intermittent sand creek flows seepage through its bed creates a large ground water mound under the creek the seasonal development and dispersion of this mound propagates pressure waves through the aquifer that influence ground water levels up to 2 km from sand creek our data suggest the primary factors contributing to wetland disappearance were recent climatic fluctuations and incision of the sand creek channel below average stream flow between 1950 and 1980 reduced the duration of sand creek flow across the dune complex minimizing ground water mound development consequently the water table in the unconfined aquifer dropped 1 0 m and interdunal wetlands dried up twentieth century incision of sand creek s channel reduced ground water mound height 2 5 m decreasing seasonal water table fluctuations at interdunal wetlands and contributing to the overall water table decline long term wet and dry cycles affect the water table elevation more than channel incision leading us to conclude that many interdunal wetlands are ephemeral features wetland area is maximized during consecutive years of above average sand creek discharge and minimized as the water table drops during dry periods

rates and spatial variations of soil erosion in europe a study based on erosion plot data an extensive database of short to medium term erosion rates as measured on erosion plots in europe under natural rainfall was compiled from the literature statistical analysis confirmed the dominant influence of land use and cover on soil erosion rates sheet and rill erosion rates are highest on bare soil vineyards show the second highest soil losses followed by other arable lands spring crops orchards and winter crops a land with a permanent vegetation cover shrubs grassland and forest is characterised by soil losses which are generally more than an order of magnitude lower than those on arable land disturbance of permanent vegetation by fire leads to momentarily higher erosion rates but rates are still lower than those measured on arable land we also noticed important regional differences in erosion rates erosion rates are generally much lower in the mediterranean as compared to other areas in europe this is mainly attributed to the high soil stoniness in the mediterranean measured erosion rates on arable and bare land were related to topography slope steepness and length and soil texture while this was not the case for plots with a permanent land cover we attribute this to a fundamental difference in runoff generation and sediment transfer according to land cover types on the basis of these results we calculated mean sheet and rill erosion rates for the european area covered by the corine database estimated rill and interrill erosion rates are ca 1 2 t ha 1 year for the whole corine area and ca 3 6 t ha 1 year 1 for arable land these estimates are much lower than some earlier estimates which were based on the erroneous extrapolation of small datasets high erosion rates occur in areas dominated by vineyards the hilly loess areas in west and central europe and the agricultural areas located in the piedmont areas of the major european mountain ranges c 2010 elsevier b v all rights reserved

vegetation and topographic controls on sediment deposition and storage on gully beds in a degraded mountain area active gully systems developed on highly weathered or loose parent material are an important source of runoff and sediment production in degraded areas however a decrease of land pressure may lead to a return of a partial vegetation cover whereby gully beds are preferred recolonization spots although the current knowledge on the role of vegetation on reducing sediment production on slopes is well developed few studies exist on the significance of restoring sediment transport pathways on the total sediment budget of degraded mountainous catchments this study in the ecuadorian andes evaluates the potential of vegetation to stabilize active gully systems by trapping and retaining eroded sediment in the gully bed and analyses the significance of vegetation restoration in the gully bed in reducing sediment export from degraded catchments field measurements on 138 gully segments located in 13 ephemeral steep gullies with different ground vegetation cover indicate that gully bed vegetation is the most important factor in promoting short term 1 15 years sediment deposition and gully stabilization in well vegetated gully systems 30 of ground vegetation cover 0 035 m 3 m 1 of sediment is deposited yearly in the gully bed almost 50 per cent of the observed variance in sediment deposition volumes can be explained by the mean ground vegetation cover of the gully bed the presence of vegetation in gully beds gives rise to the formation of vegetated buffer zones which enhance short term sediment trapping even in active gully systems in mountainous environments vegetation buffer zones are shown to modify the connectivity of sediment fluxes as they reduce the transport efficiency of gully systems first calculations on data on sediment deposition patterns in our study area show that gully bed deposition in response to gully bed revegetation can represent more than 25 per cent of the volume of sediment generated within the catchment our findings indicate that relatively small changes in landscape connectivity have the potential to create strong positive feedback loops between erosion and vegetation dynamics copyright c 2009 john wiley sons ltd

influence of soil surface features and vegetation on runoff and erosion in the western sierra madre durango northwest mexico abstract in mountainous areas runoff and soil erosion are closely linked to soil surface features particularly stoniness depending on the size of rock fragments gravel pebbles stones and or blocks and especially the way they are integrated into the soil matrix they may facilitate or hinder infiltration and promote soil losses the present study examines the role of different soil surface features and their influence on runoff formation and on soil erosion in an area seriously affected by overgrazing based on measurements made on hillslopes for 2 years at the plot scale the results show that grass cover pebbles and sand content increase runoff and erosion inversely slope value tree cover percentage structural stability and organic matter content are negatively correlated with runoff and soil losses it is shown that the correlations can be explained by the major role played by the surface features on hydrologic behaviour of the hillslopes two main surface features were identified and hydraulically characterised namely i crusted surfaces with embedded gravel widespread on gentle slopes which induce high runoff and erosion rates and ii stony surfaces where free pebbles and blocks protect the top soil against raindrops and overland flow kinetic energy and lead to reduce runoff and soil losses