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

sea ice response to atmospheric and oceanic forcing in the bering sea abstract a coupled sea ice ocean model is developed to quantify the sea ice response to changes in atmospheric and oceanic forcing in the bering sea over the period 1970 2008 the model captures much of the observed spatiotemporal variability of sea ice and sea surface temperature sst and the basic features of the upper ocean circulation in the bering sea model results suggest that tides affect the spatial redistribution of ice mass by up to 0 1 m or 15 in the central eastern bering sea by modifying ice motion and deformation and ocean flows the considerable interannual variability in the pattern and strength of winter northeasterly winds leads to southwestward ice mass advection during january may ranging from 0 9 1012 m3 in 1996 to 1 8 1012 m3 in 1976 and averaging 1 4 1012 m3 which is almost twice the january may mean total ice volume in the bering sea the large scale southward ice mass advection is constrained by warm surface waters in the south that melt 1 5 1012 m3 of ice in mainly t

sensitivity of deep convection to terrain forcing over mediterranean islands the influence of mountainous islands on the initiation of deep convection is investigated using the consortium for small scale modeling cosmo model a case study and sensitivity analysis is performed for 26 august 2009 when moist convection occurred over both corsica and sardinia islands in the western mediterranean sea sensitivity runs with systematically modified topography are explored to evaluate the relative importance of the land sea contrast and the terrain height for convection initiation whereas no island precipitation is simulated when the islands are completely removed all simulations that represent these land surfaces develop convective precipitation although convection initiates progressively earlier in the day over taller islands the precipitation rates and accumulations do not show a fixed relationship with terrain height this is due to the competing effects of different physical processes firstly whereas the forcing for low level ascent increases over taller islands the boundary layer moisture supply decreases which diminishes the conditional instability and precipitable water secondly whereas taller islands enhance the inland propagation speeds of sea breeze fronts they also block these fronts mechanically and prevent them from reaching the island interior as a result the island precipitation is rather insensitive to island terrain height except for one particular case in which the island precipitation increases considerably due to an optimal superposition of the sea breeze and upslope flow comparing the two islands convective precipitation develops earlier over corsica due to its increased terrain height and reduced convective inhibition however precipitation amounts are substantially larger over sardinia where a stronger land sea contrast gives rise to a more intense and organized line of sea breeze convergence these results demonstrate the complexity of interactions between sea breezes and orography and reinforce that an adequate representation of detailed topographic features is necessary to account for thermally induced wind systems that initiate deep convection

sea ice circulation around the beaufort gyre the changing role of wind forcing and the sea ice state sea ice drift estimates from feature tracking of satellite passive microwave data are used to investigate seasonal trends and variability in the ice circulation around the beaufort gyre over the multi decadal period 1980 2013 our results suggest an amplified response of the beaufort gyre ice circulation to wind forcing especially during the late 2000s we find increasing anticyclonic ice drift across all seasons with the strongest trend in autumn associated with increased ice export out of the southern beaufort sea into the chukchi sea a flux gate analysis highlights consistency across a suite of drift products despite these seasonal anticyclonic ice drift trends a significant anticyclonic wind trend occurs in summer only driven in part by anomalously anticyclonic winds in 2007 across all seasons the ice drift curl is more anticyclonic than predicted from a linear relationship to the wind curl in the 2000s compared to the 1980s 1990s the strength of this anticyclonic ice drift curl amplification is strongest in autumn and appears to have increased since the 1980s up to 2010 in spring and summer the ice drift curl amplification occurs mainly between 2007 and 2010 these results suggest non linear ice interaction feedbacks e g a weaker more mobile sea ice pack enhanced atmospheric drag and or an increased role of the ocean the results also show a weakening of the anticyclonic wind and ice circulation since 2010 this article is protected by copyright all rights reserved

spatial distribution of surface conditions and runoff generation in small arid watersheds zin valley badlands israel abstract high rill density may be regarded as indicative of frequent and integrated runoff along a drainage network however field observations of soil development and rill geometry in small first order catchments 0 1 to 1 ha of the zin valley badlands northern negev israel suggest a pattern of partial area contribution and frequent flow discontinuities along hillslopes and channels changing soil properties associated with an increase of slope angle and slope length appear to be responsible for high infiltration on the slopes leading to nonuniform runoff generation within small drainage basins runoff observation sprinkling tests and soil analysis along ridges and sideslopes were carried out to test this hypothesis the results confirmed that infiltration capacity on the sideslopes is significantly higher than on the ridges under current rainfall conditions only extreme rainfall intensities are sufficient to generate runoff along entire slopes the discontinuous nature of most runoff events causes erosion on ridges and deposition on slopes which enhances soil development on the valley sideslopes creating a positive feedback on infiltration rate and depth this demonstrates that the links between within storm rainfall conditions and spatial distribution of soil characteristics have to be incorporated into our understanding of landscape development in badlands

on the effects of islands geometry and size on inducing sea breeze circulation abstract model scaling of the characteristics of the sea breeze circulation involved with circular and slab elongated symmetric midlatitude islands was performed larger horizontal and vertical velocities were indicated over the small circular islands as compared to those over corresponding elongated islands the circulation characteristics of both types of islands become similar when the half width of the island is about the same as the distance of inland penetration of the sea breeze in a nonisland case evaluation of the results through a wale analysis is presented

upper pleistocene holocene geomorphic changes dictating sedimentation rates and historical land use in the valley system of the chifeng region inner mongolia northern china this study focuses on the late quaternary landscape evolution in the chifeng region of inner mongolia china its relations to the history of the pleistocene holocene loess accumulation erosion and redeposition and their impact on human occupation based on 57 optically stimulated luminescence osl ages of loess sediments fluvial sand and floodplain deposits accumulated on the hill slopes and floodplains we conclude that during most of the pleistocene period the region was blanketed by a thick layer of aeolian loess as well as by alluvial and fluvial deposits the loess section is divided into two main units that are separated by unconformity the osl ages at the top of the lower reddish loess unit yielded an approximate age of 193 ka roughly corresponding to the transition from mis 7 to 6 though they could be older the upper gray loess unit accumulated during the upper pleistocene glacial phase mis 4 3 at a mean accumulation rate of 0 22 m ka parallel to the loess accumulation on top of the hilly topography active fans were operating during mis 4 2 at the outlet of large gullies surrounding the major valley at a mean accumulation rate of 0 24 m ka this co accumulation indicates that gullies have been a long term geomorphic feature at the margins of the gobi desert since at least the middle pleistocene during the holocene the erosion of the pleistocene loess on the hills led to the burial of the valley floors by the redeposited sediments at a rate that decreases from 3 2 m ka near the hills to 1 0 4 m ka1 in the central part of the chifeng valley this rapid accumulation and the frequent shifts of the courses of the river prevented the construction of permanent settlements in the valley floors a situation which changed only with improved man made control of the local rivers from the tenth century ad copyright 2010 john wiley sons ltd

sheet erosion rates determined by using dendrogeomorphological analysis of exposed tree roots two examples from central spain this paper describes the determination of sheet erosion rates by using dendrogeomorphological methods on exposed tree roots two sites on the northern slope of the guadarrama mountains central spain were studied a popular trail in a scots pine forest senda schmidt valsain growing on granites and gneisses and an open holm oak forest on granitic slopes monterrubio these sites were selected because they showed high denudation morphologies due to accelerated soil erosion processes caused by human influence trampling by continuous trekking and overgrazing resulting in exposed roots the method applied is based on the morphological pattern of roots defined by the growth ring series of the sampled roots in order to confirm the validity of the criteria used and to make the estimations of erosion more accurate several anatomical indicators of exposed and non exposed pinus sylvestris roots were characterized the study entailed a statistical analysis of exposure time and erosion depth the influence of environmental factors affecting the variation in velocity of the erosion processes was also examined

seasonal patterns of runoff and erosion responses to simulated rainfall in a badland area in mediterranean mountain conditions vallcebre southeastern pyrenees regolith surface characteristics and response were examined over a three year period in a badland area in a mediterranean middle mountain zone near vallcebre eastern pyrenees preliminary work carried out in this area indicated clear seasonal patterns of regolith properties driven by frost heaving in winter and crusting and erosion in the rest of the year rainfall simulations were performed with a small portable nozzle simulator in order to study seasonal changes in runoff generation erosion rates and raindrop effect on bulk density changes the results showed large seasonal variations in runoff and erosion responses in ltration rates after runoff start were correlated with precipitation depth before runoff start runoff generation was therefore related to regolith saturation only to a very limited extent erosion rates were more controlled by runoff rates than by the weakness of regolith against raindrop splash and sediment grain size increased with concentration the combined role of antecedent regolith moisture and bulk density explained most of the seasonal variability in in ltration bulk density changes during rainfall and erosion rates but some seasonal differences in sediment detachability were not explained by these variables and may be attributed to changes in roughness overall runoff and erosion responses were relatively stable during spring and autumn whereas wide variations in in ltration rates and sediment detachment occurred in winter and summer respectively experiments conducted in a single season would have produced poorly representative if not erroneous results copyright 2004 john wiley sons ltd

an investigation of convection behind the cape canaveral sea breeze front abstract a three dimensional numerical simulation of land water circulations near cape canaveral florida is performed using the advanced regional prediction system the role of kelvin helmholtz instability khi in determining the time and location of convection behind the sea breeze front is examined the model configuration attempts to improve upon limitations of previous work e g resolution surface characteristics initial state it provides a detailed and realistic simulation of the desired features the simulation exhibits a single precipitating storm that forms behind the sea breeze front this postfrontal storm develops when an outflow boundary intersects a deep layer of upward motion above the marine air the region of ascent initially is the remnant of a cell that formed along the sea breeze front but before the cell decays a portion of its upward motion is intensified and displaced the modification of the ascent is a product of khi that is occurring on top of the sea breeze interface i

erosion rates in badland areas recorded by collectors erosion pins and profilometer techniques ebro basin ne spain abstract in badland areas of the ebro basin in a semiarid climate two erosion plots 257 m2 5 slope and 128 m2 23 slope on exposed tertiary clays were monitored over two years nov 1991 nov 1993 this material is characterized by high sodium absorption ratios which lead to high soil dispersivity the dominant erosion processes in both plots are rilling and sheet erosion rainfall intensity was recorded at a weather station connected to a data logger sediment production for single events was collected in tanks and ground lowering was measured every six months by erosion pins and microtopographic profile gauge techniques significant runoff was produced only by rainfall events above 5 mm another threshold at 20 mm rain was noted for rainfalls higher than 20 mm the 23 slope plot shows a greater runoff response than the 5 one rainfall events exceeding this threshold showed a higher sediment production for the steeper slope in the relationship between precipitation and sediment concentration an envelope curve can be drawn indicating that any rainfall event of a given amount and intensity has a maximum sediment concentration which we speculate to be a function of the runoff sediment transport capacity runoff response and sediment yield in the studied plots are controlled by the rainfall and soil characteristics and their seasonal variations in both plots the erosion pins show that erosion rates in rill areas are 25 50 higher than in the interrill areas sediment yield recorded by collector devices was higher than the rates measured by erosion pins the erosion rates based on rill cross sections by profilometers were higher than the ones recorded by collectors

shallow mesoscale flows at the north eastern adriatic coast a summertime anticyclonic situation over the northern part of the eastern adriatic coast is studied using a three dimensional nonhydrostatic mesoscale model the aim is to evaluate small scale variability such as mesoscale eddies sea breeze convergence zones czs and the coastal jet like flow in the thermally driven mesoscale circulations over very complex terrain the results show that the model reproduces main known features of the diurnal flow with certain local specific characteristics in addition to some new ones previously only somewhat qualitatively known after comparisons with measurements further analyses are performed by sensitivity tests in which topography and synoptic input are varied the simulations show a development of two diurnal intensive mesoscale eddies inside kvarner bay 20 km 20 km the night time deeper eddies exhibit anticlockwise rotation while the late afternoon shallow one shows the opposite rotation their appearance and dynamics are connected primarily to the coastline shape and topography meanwhile the large scale flow in the anticyclonic weather type as addressed here has small influence moreover a cz develops over istria and the island of krk as a result of merged sea breezes the intensity speed position and configuration of the sea breeze cells are examined the results also show that the topography is more important for the formation of the cz over the island of krk and for the coastal jet like flow between the island and mainland than for the istrian cz copyright 2006 royal meteorological society

investigation of relationships between measured field indicators and erosion processes on badland surfaces at petrer spain abstract indicators were obtained to measure and predict rill erosion and mass wasting in biancana and calanchi like badland areas rainfall simulation experiments were used to find a relationship between soil moisture change and sediment concentration behaviour this relationship appeared to be able to show in its role as indicator differences between materials affected by various degrees of rill erosion or mass wasting indicators explaining this relationship are surface characteristics runoff and infiltration characteristics and chemical and mineralogical soil properties from the experimental study it was concluded that the high infiltration capacity in materials affected by mass wasting resulted in an unstable soil and a high degree of erodibility the materials which were more affected by rill erosion or had a continuous crust at the surface were saturated earlier during the experiment than the other materials this saturation caused an increase in runoff the mechanism is explained as the system crossing a threshold after which flow hydraulics at the surface are more important for erosion processes than dynamic soil properties and infiltration characteristics

sea ice response to wind forcing from amip models abstract the arctic surface circulation simulated by atmospheric general circulation models is assessed in the context of driving sea ice motion a sea ice model is forced by geostrophic winds from eight models participating in the first atmospheric model intercomparison project amip1 and the results are compared to simulations with the sea ice model forced by observed winds the mean sea level pressure in the amip models is generally too high over the arctic ocean except in the beaufort and chukchi seas where it is too low this pattern creates anomalous winds that tend to transport too much ice away from the coast of greenland and the canadian archipalego and into the east siberian sea producing a pattern of ice thickness in the arctic that is rotated by roughly 180 relative to what is expected based on observations amip winds also drive too little ice transport through fram strait and too much transport east of svalbard by way of the barents sea these errors in ice thickness and transport inf

response of sea ice drift to wind forcing on the northeastern newfoundland shelf observations of sea ice drift obtained with satellite tracked ice beacons in march april of 1988 and 1989 have been used to examine the response of sea ice drift to wind forcing over the northern newfoundland continental shelf the short term 5 20 days response of sea ice drift ranges from 2 6 to 5 4 of the local wind over much of the inner continental shelf which is comparable to that in the bering sea and the antarctic but larger than that in arctic sea ice drifts to the right of the local wind at angles ranging from 10 to 63 the response to wind forcing is largest near the ice edge both over the middle portions of the shelf and along the southern margins of the seasonal ice zone and during strong and steady wind of several days duration the large wind driven response of ice drift observed in this study in comparison with the arctic may result from 1 reduced levels of internal ice stress associated with the generally thin ice cover and lower areal concentration of sea ice 2 large atmospheric drag coefficients associated with the small ice floes in areas of comparatively higher ice concentration and 3 smooth ice bottom caused by melting in nearshore areas the ice to wind coupling is reduced owing to larger internal ice stresses experienced locally due to ice pileup

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

high resolution quantification of gully erosion in upland peatlands at the landscape scale the upland peatlands of the uk are severely eroded with large areas affected by gully erosion the peatlands are important areas of carbon storage and provide a range of other ecosystem services including water supply and biodiversity all of which are negatively impacted by erosion of the upland surface the magnitude of the gully erosion and consequent adjustment of the peatland morphology is such that in degraded peatlands the extent and magnitude of erosion is a major control on peatland function accurate mapping of gully form is therefore a necessary precondition to the understanding and management of these systems this paper develops an approach to extracting gully maps from high resolution digital elevation models dems gully maps of the bleaklow plateau in northern england were derived from a 2 m lidar dem by combining areas of low difference from mean elevation and high positive plan curvature gully depth was modelled by interpolating between gully edges testing of the gully mapping and depth modelling against aerial photography manual interpretation of the dem and ground survey revealed that gully plan form is well represented and gully width and depth are modelled with tolerances close to the horizontal and vertical resolution of the lidar imagery estimates of gully width and depth were less reliable for gullies with total width of less than four pixels the approach allows for the first time the derivation of accurate estimates of gully extent and magnitude over large areas and provides the basis for modelling a range of processes controlled by gullying the approach has wider applicability to mapping gully erosion in a wide range of environments copyright 2010 john wiley sons ltd

barents sea tidal and inertial motions from argos ice buoys during the coordinated eastern arctic experiment a harmonic analysis constrained to estimate separately ice motions forced by tides and inertial oscillations was applied to observed positions of argos buoys deployed on drifting multiyear sea ice in the eastern arctic ocean and barents sea during the coordinated eastern arctic experiment 1988 1989 individual tidal components were estimated at 15 day intervals and inertial oscillations were estimated at 3 day intervals the s2 tidal component was distinguishable from inertial motions south of 79 n and the m2 tidal component was distinguishable from the inertial motion north of 77 5 n computed ice velocities of up to 70 cm s 1 for m2 tidal motion over spitsbergen bank southeast of svalbard agreed reasonably well with the regional tidal models no ice cover of gjevik and of kowalik regional differences in the energy distribution in the arctic basin low barents shelf high and spitsbergen bank extreme were emphasized by this technique the m4 tidal component in the ice motion was typically as large over the barents shelf as the inertial oscillation

the force balance of sea ice in a numerical model of the arctic ocean the balance of forces in the sea ice model of hibler 1979 is examined the model predicts that internal stress gradients are an important force in much of the arctic ocean except in summer when they are significant only off the northern coasts of greenland and the canadian archipelago a partition of the internal stress gradient between the pressure gradient and the viscous terms reveals that both are significant although they operate on very different timescales the acceleration term is generally negligible while the sum of coriolis plus sea surface tilt is small thus the seasonal average force balance in fall winter and spring is mostly between three terms of roughly equal magnitudes air drag water drag and internal stress gradients this is also true for the monthly average force balance however we find that there is a transition around the weekly timescale and that on a daily basis the force balance at a particular location and time is often between only two terms either between air drag and water drag or between air drag and internal stress gradients the model is in agreement with the observations of thorndike and colony 1982 in that the correlation between geostrophic wind forcing and the model s ice velocity field is high this result is discussed in the context of the force balance we show that the presence of significant internal stress gradients does not preclude high wind ice correlation a breakdown of the internal stress gradient into component parts reveals that the shear viscous force is far from negligible which casts strong doubt on the theoretical validity of the cavitating fluid approximation in which this component is neglected finally the role of ice pressure is examined by varying the parameter p we find a strong sensitivity in terms of the force balance as well as ice thickness and velocity

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

when land breezes collide converging diurnal winds over small bodies of water over enclosed and semi enclosed bodies of water the land breeze sea breeze circulation is expected to be modified by the presence of opposing coastlines these effects are studied using satellite scatterometer surface wind observations from the quikscat and adeos 2 tandem mission from april october 2003 winds are studied for six bodies of water the red sea the gulf of california the mediterranean the adriatic sea the black sea and the caspian sea these bodies of water are large enough for the geographic orientation of the diurnal winds relative to the coastline to match the expected orientation for a straight coastline land breezes from opposite coastlines converge in the middle of these bodies of water and in some cases the convergence line is shifted substantially away from the midpoint between opposite coastlines displacements in the convergence line appear likely to be explained by differences in the strength of the diurnal winds emanating from opposite coastlines associated with differential heating or island peninsula effects and by geographic displacements associated with large scale mean wind patterns

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

factors controlling the erosion rates in a semi arid zone bardenas reales ne spain abstract bardenas reales is an erosive depression 415 km 2 in area located in the central western part of the ebro depression tertiary sediments crop out in the margin of the basin whereas quaternary sediments holocene in age occur only in its centre these holocene sediments clays and silts are the result of the erosion and weathering of the tertiary clays and are made up of 3 different stratigraphic units erosion is clearly the dominant process in the centre of the depression generating gullies up to 10 km in long and 8 m deep in order to analyse and quantify the erosion rates of the studied area erosion was measured on two soil erosion plots with volumetric and instrumental techniques that have been supplied for the last 12 years the results show that the estimated erosion rates depend extrinsically on the used method and intrinsically on the time of the year in which they are measured the most accurate values are those obtained by means of collector devices the values obtained by the microtopographic profile gauge are overestimated while the results of the measurement with erosion pins are clearly lower the study area is located in a semi arid environment with two pluviometric maximums in spring and autumn associated with convective storms in summer and winter rainfall is related to atlantic cyclonal fronts soil loss is significant during the pluviometric maximums when rainfall quantity and intensity are higher during cyclonal periods in contrast water erosion is null or scarce and soil loss is related to mudflows in addition the erosion rates of each holocene unit are different the c2 holocene unit has undergone greater erosion because of its physico chemical properties all the stratigraphic units have similar characteristics regarding tertiary materials since 1993 the average erosion rate measured by the collector device on the tertiary materials is 32 mg ha 1 year 1 and 77 mg ha 1 year 1 in the holocene

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

relative influences of the metocean forcings on the drifting ice pack and estimation of internal ice stress gradients in the labrador sea understanding the relative influences of the metocean forcings on the drift of sea ice floes is a crucial component to the overall characterization of an ice environment and to developing an understanding of the factors controlling the ice dynamics in addition estimating the magnitude of the internal stress gradients on drifting sea ice floes generated by surrounding ice cover is important for modeling operations informing the design of offshore structures and vessels in ice environments and for the proper calibration of discrete element models dem of fields of drifting ice floes in the spring of 2015 and 2016 four sea ice floes offshore makkovik labrador were tagged with satellite linked ice tracking buoys along with one satellite linked weather station on each floe to transmit wind speed and direction twenty satellite linked lagrangian surface ocean current tracking buoys were also deployed in the open water adjacent to the targeted ice floes in this paper the dynamics of the four ice floes are explored in terms of the relative proportions which were forced by the wind current sea surface topography coriolis and internal stress gradients the internal ice stress gradients are calculated as residuals between the observed accelerations of the floes as measured by the tracking buoys and the sums of the other metocean forcings results show that internal ice stress gradients accounted for up to 50 of the observed forcing on the floes and may have reached up to around 0 19kpa

evaluation of the relative contribution of meteorological and oceanic forces to the drift of ice islands offshore newfoundland on 29 april 2015 four beacons were deployed onto an ice island in the strait of belle isle to record positional data the ice island later broke up into many fragments four of which were tracked by the beacons the relative influences of wind drag current drag coriolis force sea surface height gradient and sea ice force on the drift of the tracked ice island fragments were analyzed using atmospheric and oceanic model outputs the sea ice force was calculated as the residual of the fragments net forces and the sum of all other forces this was compared against the force obtained through ice concentration dependent relationships when sea ice was present the sea ice forces calculated from the residual approach and concentration dependent relationships were significant only when sea ice was present at medium high concentrations in the vicinity of the ice island fragments the forces from ocean currents and sea surface tilt contributed the most to the drift of the ice island fragments wind however played a minimal role in the total force governing the drift of the four ice island fragments and coriolis force was significant when the fragments were drifting at higher speeds