a pseudo genetic stochastic model to generate karstic networks summary in this paper we present a methodology for the stochastic simulation of 3d karstic conduits accounting for conceptual knowledge about the speleogenesis processes and accounting for a wide variety of field measurements the methodology consists of four main steps first a 3d geological model of the region is built the second step consists in the stochastic modeling of the internal heterogeneity of the karst formations e g initial fracturation bedding planes inception horizons etc then a study of the regional hydrology hydrogeology is conducted to identify the potential inlets and outlets of the system the base levels and the possibility of having different phases of karstification the last step consists in generating the conduits in an iterative manner using a fast marching algorithm in most of these steps a probabilistic model can be used to represent the degree of knowledge available and the remaining uncertainty depending on the data at hand the conduits are assumed to follow minimum effort paths in a heterogeneous medium from sinkholes or dolines toward springs the search of the shortest path is performed using a fast marching algorithm this process can be iterative allowing to account for the presence of already simulated conduits and to produce a hierarchical network the final result is a stochastic ensemble of 3d karst reservoir models that are all constrained by the regional geology the local heterogeneities and the regional flow conditions these networks can then be used to simulate flow and transport several levels of uncertainty can be considered large scale geological structures local heterogeneity position of possible inlets and outlets phases of karstification compared to other techniques this method is fast to account for the main factors controlling the 3d geometry of the network and to allow conditioning from available field observations

hydrogeological characterization of groundwater storage and drainage in an alpine karst aquifer the kanin massif julian alps the kanin massif is an important trans boundary aquifer which stretches between slovenia and italy the groundwater is only partially exploited mainly for water supply but the aquifer exhibits great potential for future exploitation since no consistent regional overview of the hydrogeological functioning of the kanin massif was available the decision was made to perform a study of this area using a pragmatic approach based on 3d geological and hydrogeological modelling the so called karsys approach was applied with the aim of characterizing the groundwater reserves within this karst massif and of locating the main drainage axes that carry groundwater from the recharge areas to the respective springs delineation of the catchment areas of the corresponding springs was carried out and some new explanations were obtained especially with regard to the mo nica spring which is located in slovenia and forms a potential source of drinking water it was found that this spring s catchment area extends as far as the italian ski resort of sella nevea the conceptual model also provides a possible explanation about the underground drainage towards the boka spring and waterfall which has been a challenge for decades this new explanation is based on the existence of a perched groundwater body that feeds the boka spring via a system of conduits despite some limitations the results which consist of a visualization of the underground drainage and groundwater storage within the kanin massif can be used as a basis for planning the sustainable management of karst waters in the studied area copyright 2014 john wiley sons ltd

emplacement of the cuera and picos de europa imbricate system at the core of the iberian armorican arc cantabrian zone north spain new precisions concerning the timing of arc closure the final stages of the variscan orogeny mostly carboniferous in the western european variscan belt involved the development of the iberian armorican arc which is cored by the cantabrian zone nw iberia the cantabrian zone is the foreland of the western european variscan belt and it is interpreted to record the waning stages of the closure of the rheic ocean the distalmost tectonic units within the cantabrian zone the cuera unit and the picos de europa province were the last tectonic units emplaced at the core of the western european variscan belt orocline together they form an imbricate system and associated wedge top basins that are key to understanding the development of the orocline the emplacement of the cuera unit and the picos de europa province occurred in the latest pennsylvanian between moscovian and gzhelian times new detailed mapping together with stratigraphic sedimentologic and biostratigraphic data analysis of syntectonic successions and structural information constrain the timing and evolution of this imbricate system our analysis indicates that the thrust sheets were emplaced roughly perpendicular to previous tectonic units of the cantabrian variscan foreland fold and thrust belt most probably during the oroclinal bending of the sw european variscan belt that formed the iberian armorican arc the n s directed imbricate system was characterized by a shallow dip of the topographic surface 150 15 km and complex structure of the orogenic wedge are thought to result from the progressive increase in the dip of the basal decollement during bending of the underlying gondwana lithosphere and may reflect the closure of the iberian armorican arc

simulation of 3d karst conduits with an object distance based method integrating geological knowledge karst conduit shapes have a high influence on fluid flows as these underground hidden systems are partially inaccessible their stochastic simulation is an essential tool to assess the uncertainties related to these highly exploited water resources the object distance simulation method odsim is a hybrid dual scale approach that has been recently proposed to model geological underground structures due to late processes such as dolomitized rocks mineralized veins or karsts using a perturbed euclidean distance field around a curve representing roughly the conduit centre and called a skeleton the resulting shapes are globally cylindrical like 3d envelopes but at a drain scale karstic conduits are elongated along weakness planes such as lithostratigraphic horizons bedding planes fractures or faults in addition to those planes the influence of the water table is added this work presents different improvements of odsim methodology for simulating more realistic shapes in the particular case of karst firstly we propose using a custom distance field computed with a fast marching method considering the velocity field to be proportional to the permeability allows the resulting features to be elongated along the weakness planes secondly to handle specific shapes due to the proximity of the water table such as trenches or notches we impose areas of higher velocity between the skeleton and the water table finally we generate a custom random threshold with several variograms and or distributions depending on the different features integrated in the velocity field applied on different models it is shown that the resulting karst conduits have more realistic shapes than those obtained with the previous workflow while the variability of structures which can be modelled with odsim is preserved

analysis of velocity profile measurements from wind tunnel experiments with saltation abstract investigations of wind field modification due to the presence of saltating sediments have relied heavily on wind tunnels which are known to impose geometric constraints on full boundary layer development there remains great uncertainty as to which portion of the vertical wind speed profile to analyze when deriving estimates of shear velocity or surface roughness length because the lower sections are modified to varying degree by saltation whereas the upper segments may be altered by artificially induced wake like effects thus it is not obvious which of several alternative velocity profile parameterizations e g law of the wall velocity defect law wake law should be employed under such circumstances a series of experimental wind tunnel runs was conducted across a range of wind speed using fine and coarse grained sand to collect high quality fine resolution data within and above the saltation layer using thermal anemometry and ruggedized probes after each run the rippled bottom was fixed with fine mist and the experiment repeated without saltation the measured wind speed profiles were analyzed using six different approaches to derive estimates of shear velocity and roughness length the results were compared to parameter estimates derived directly from sediment transport rate measurements and on this basis it is suggested that one of the six approaches is more robust than the others specifically the best estimate of shear velocity during saltation is provided by the logarithmic law applied to the profile data within about 0 05 m of the bottom despite the fact that this near surface region is where profile modification by saltating sediments is most pronounced uncertainty remains as to whether this conclusion can be generalized to field situations because progressive downwind adjustments in the interrelationship between the saltation layer and the wind field are anticipated in wind tunnels thereby confounding most analyses based on equilibrium assumptions

implications for karst hydrology from 3d geological modeling using the aquifer base gradient approach we use the gradient of the aquifer base to investigate the hydrology of mature shallow karst systems we first present a 3d geological model of the gempen plateau nw switzerland that reveals the geometry of aquifers and aquitards and their displacement at faults then transfer the 3d geological model to a hydrological model the transformation is based on a conceptual karst model approximating subsurface flow in mature shallow karst systems to open surface flow on the top of the uppermost aquitard or aquifer base the gradient of this surface is expected to mainly influence regional groundwater flow patterns we use the hydrological model to delineate spring catchment areas the discharge areas and corresponding catchment areas of the model are compared with the occurrence of springs in the study area and with hydraulic links confirmed by tracer tests we also describe the way in which the hydrological model contributes to identifying flow processes the proposed aquifer base gradient approach enhances vulnerability assessment in mature shallow karst regions by 1 localizing catchment areas as a precondition of source protection strategies and 2 indicating dominant flow processes associated with individual springs

a wind tunnel study of aeolian sediment transport response to unsteady winds abstract although moderate attention has been paid to the response of the aeolian mass transport rate to wind gusts it is still unclear how the particle size and volumetric concentration affect this relation very little is known about the response time of the particle speed and specifically how the sensor scale and elevation affect measurements of this variable the present study addresses this knowledge gap through a series of wind tunnel experiments in which a gusty wind was generated by programming the fan motor to adjust to a randomly selected rpm every 10 s beds consisting of either medium or coarse sand were investigated through synchronous co located measurements of the local wind speed and particle speed count rate obtained via a customized laser doppler anemometry lda system the vertically integrated sand transport rate q and the wind speed in the freestream were quantified using a passive sand trap and pitot tube respectively the results of the experiments indicate that the response of the aeolian transport system to wind gusts is generally faster in terms of the particle speed than the mass transport rate while the degree of correlation is found to vary with the sensor elevation as well as with the particle size and volumetric concentration in essence the coupling within the transport system is demonstrated to be strongly scale dependent

rates of aerodynamic entrainment in a developing boundary layer despite its significance for inception of grain transport by wind the initial dislodgement of grains from a static surface by aerodynamic forces of drag and lift in the absence of grain collision has received little attention this paper describes a series of wind tunnel experiments in which the erosion of narrow strips of loose grains from the roughened surface of a flat plate exposed to a range of wind speeds was examined the progressive downwind development of the boundary layer over the plate provided a range of airflow conditions which permitted systematic evaluation of grain entrainment rates arising from purely aerodynamic forces use of closely graded size fractions in flat single grain layers resting on identical fixed grain support eliminated the effects of surface irregularities and impacts from saltation results show that erosion of strips of loose grains develops with time according to an inverse exponential function in which the entrainment rate time constant relates to shields dimensionless shear stress function an empirical expression defining aerodynamic entrainment rate in terms of rate of strip erosion is derived and comparisons are made between present and published data the need for additional data to resolve several questions raised by the present investigation is stressed in addition a simple objective technique for accurate determination of the aerodynamic entrainment threshold of any loose granular sediment is proposed

large eddy simulation of sand transport under unsteady wind abstract aeolian sand movement contributes to evolution of surface landforms on earth and mars as well as on venus and titan most natural landforms in arid regions are molded by wind with a general feature of unsteadiness many researches have improved our cognition of saltation in unsteady flow but it is probably true that this issue is not yet fully analysed in this paper we conducted three dimensional numerical simulations of wind blown sand under unsteady wind conditions the trajectories of sand particles are simulated by using a lagrangian model particle motion particle bed interaction and wind modification have been taken into account results indicate that the characteristics of sand transport in unsteady and steady wind conditions profoundly differ the sediment transport in unsteady conditions is significantly enhanced and increases with the amplitude of the sinusoidal wind fluctuations the time series of sediment transport reveals a sine like variation which lags behind the variation of the wind with a time delay of about 1 s response time of saltation to wind variation in unsteady conditions sand transport shows an overshoot which is embodied in the initial wave of the sediment transport the impact of unsteady sediment transport should be paid more attention in future aeolian research

a pennsylvanian microbial boundstone dominated carbonate shelf in a distal foreland margin picos de europa province nw spain abstract a pennsylvanian bashkirian moscovian high rising microbial boundstone dominated carbonate platform 12 000 km2 developed in the external margin of a variscan foreland basin intensely studied in the northern domain cuera area the stratigraphy and sedimentology of the southern domain the picos de europa province is here revisited distribution of the bashkirian facies valdeteja formation defines a ramp low angle platform with an internal zone central and eastern sectors of the picos de europa province consisting of huge amounts of massive cement rich microbial boundstones surrounded by an external zone comprising lower slope boundstone derived breccias and basinal lime mudstones from the bashkirian moscovian transition to the early kasimovian picos de europa formation the carbonate platform moderately aggraded acquiring a high rising and flat topped geometry and then prograded rapidly into the external zone where platform derived carbonate sediment and clay sourced from the orogen were deposited seismic scale exposures of the western margin of the shelf show angular bedding relationship between basin toe of slope slope and platform top stratal domains with slope inclination up to 32 and a topographic relief of 550 m the platform evolution above described for the picos de europa province significantly differs with respect to the cuera area where platform mostly prograded during the bashkirian and subsequently aggraded during early moscovian the evolutionary differences between these two carbonate domains which are geographically close are interpreted as changes in tectonic subsidence distribution acting as the major factor controlling the large scale platform geometries in the active foreland basin context finally the tectonic overload due to the emplacement of the cuera thrust sheets during the moscovian kasimovian transition changed the platform growth style from progradational to aggradational and consequently the stacking pattern of the platform top cycles in the picos de europa province

modeling spatially and temporally varied hydraulic behavior of a folded karst system with dominant conduit drainage at catchment scale hochifen gottesacker alps summary karst aquifers are important for freshwater supply but difficult to manage due to highly variable water levels and spring discharge rates conduits are crucial for groundwater flow in karst aquifers but their location is often unknown thus limiting the applicability and validity of numerical models we have applied a conduit model swmm to simulate highly variable flow in a folded alpine karst aquifer system where the underground drainage pattern is comparatively well known from previous tracer studies the conduit model was coupled with a reservoir model representing recharge storage and transfer of water in the epikarst and unsaturated zone the global optimization approach ga was applied to achieve an efficient model calibration it was possible to simultaneously simulate the highly variable discharge characteristics of an estavelle and overflow spring and a permanent spring draining the conduit system the model allowed for the collection of spatially differentiated information on recharge rapid flow and slow flow in four individual sub catchments the formation of backwater upgradient from conduit restrictions turned out to be a key process in activating overflow springs the proposed modeling approach appears to be transferrable to other karst systems with predominant conduit drainage but requires previous knowledge of the configuration of the conduit system

a comprehensive numerical model of steady state saltation comsalt 1 the blowing of sand by wind known as saltation ejects dust aerosols into the atmosphere creates sand dunes and erodes geological features we present a comprehensive numerical model of steady state saltation comsalt that in contrast to most previous studies can reproduce a wide range of measurements and can simulate saltation over mixed soils comsalt calculates the motion of saltating particles due to gravity fluid drag particle spin fluid shear and turbulence and explicitly accounts for the retardation of the wind due to drag from saltating particles furthermore we included a novel physically based parameterization of the ejection of surface particles by impacting saltating particles which matches experimental results comsalt is the first numerical saltation model to reproduce measurements of the wind shear velocity at the impact threshold i e the lowest shear velocity for which saltation is possible and of the aerodynamic roughness length in saltation it also reproduces a range of other saltation processes including profiles of the wind speed and particle mass flux and the size distribution of saltating particles as such comsalt is the first physically based numerical model to reproduce such a wide range of experimental data since we use a minimum of empirical relations comsalt can be easily adapted to study saltation under a variety of physical conditions such as saltation on other planets saltation under water and saltating snow

modelling hydrostratigraphy and groundwater flow of a fractured and karst aquifer in a mediterranean basin salento peninsula southeastern italy the control exerted by the hydrostratigraphic structure on aquifer recharge groundwater flow and discharge along the coastal areas of a mediterranean basin salento peninsula about 5 000 km2 wide southern italy is assessed through the development and application of a groundwater flow model based on the reconstruction of the hydrostratigraphic architecture at the regional scale the hydrostratigraphic model obtained by processing surface and subsurface data is applied to map the top of the main aquifer which is hosted in the deep hydrostratigraphic unit corresponding to cretaceous and oligocene limestones with complex geometrical relationships with the sea it is also used to estimate the aquifer recharge which occurs by percolation through overlying younger sediments with low permeability these data are completed with information about the soil use to estimate water abstraction for irrigation and with literature data to estimate the water abstraction for drinking and industrial purposes the above sketched conceptual model is the basis for a finite difference groundwater 2d pseudo stationary flow model which assumes the following fundamental approximations the fractured and karst limestone hydrostratigraphic unit can be approximated at the model scale as a continuous medium for which the discrete darcy s law is valid the transition zone between salt and fresh water is so small with respect to the grid spacing that the ghyben herzberg s approximation for a sharp interface can be applied along the coastline different boundary conditions are assigned if the top of the limestone hydrostratigraphic unit lies either above the sea level the aquifer has a free surface and fresh water is drained or below the sea level the aquifer is under pressure and the contact with sea occurs off shore the groundwater flow model correctly predicts the areas where the aquifer is fully saturated with salt water

a multi method approach for speleogenetic research on alpine karst caves torca la texa shaft picos de europa spain abstract speleogenetic research on alpine caves has advanced significantly during the last decades these investigations require techniques from different geoscience disciplines that must be adapted to the methodological constraints of working in deep caves the picos de europa mountains are one of the most important alpine karsts including 14 of the world s deepest caves caves with more than 1 km depth a speleogenetic research is currently being developed in selected caves in these mountains one of them named torca la texa shaft is the main goal of this article for this purpose we have proposed both an optimized multi method approach for speleogenetic research in alpine caves and a speleogenetic model of the torca la texa shaft the methodology includes cave surveying dye tracing cave geometry analyses cave geomorphological mapping uranium series dating 234u 230th and geomorphological structural and stratigraphical studies of the cave surroundings the speleodisc method was employed to establish the structural control of the cavity torca la texa 2653 m length 215 m depth is an alpine cave formed by two cave levels vadose canyons and shafts soutirage conduits and gravity modified passages the cave was formed prior to the middle pleistocene and its development was controlled by the drop of the base level producing the development of the two cave levels coevally to the cave levels formation soutirage conduits originated connecting phreatic and epiphreatic conduits and vadose canyons and shafts were formed most of the shafts were created before the local glacial maximum 43 45 ka and only two cave passages are related to dolines developed in recent times the cave development is strongly related to the structure locating the cave in the core of a gentle fold with the conduits geometry and orientation controlled by the bedding and five families of joints

karsys a pragmatic approach to karst hydrogeological system conceptualisation assessment of groundwater reserves and resources in switzerland an approach is presented for the hydrogeological conceptualisation of karst systems the karsys approach helps hydrogeologists working in karst regions to address in a pragmatic and efficient way the three following questions 1 where does the water of a karst spring come from 2 through which underground routes does it flow 3 what are the groundwater reserves and where are they it is based on a three dimensional model of the carbonate aquifer geometry 3d geological model coupled to a series of simple fundamental principles of karst hydraulics this provides within a limited effort a consistent hydrogeological conceptual model of karst flow systems within any investigation area the level of detail can be adjusted according to the targeted degree of confidence two examples of its application are presented the approach was first applied with a low level of detail on a national scale in order to assess the groundwater reserves in karst aquifers in switzerland suggesting a groundwater volume of 120 km3 on a regional scale it was applied with a higher level of detail to some selected karst systems in order to assess their hydropower potential the karsys approach may provide very useful information for water management improvement in karst regions vulnerability assessment impact assessment water supply flood hazards landslides etc it leads in a very cost effective manner to a new and highly didactic representation of karst systems as well as to new concepts concerning the delineation of catchment areas in karst regions

speleodisc a 3 d quantitative approach to define the structural control of endokarst an application to deep cave systems from the picos de europa spain abstract the influence of geological structure on endokarst can be studied by establishing the relationships between discontinuities faults joints and bedding with a cave survey the cave survey elaborated by speleologists represents the directions and inclinations of the cave conduits and can be compared to the strike and dip of the discontinuities of a karst massif this paper proposes a methodology the speleodisc method which is effective in defining the structural control of the endokarst the method has been designed and applied in a pilot area from the alpine karst massif of the picos de europa where long and deep cave systems are well developed including more than 360 km of conduits in its entirety the method is based on the projection of cave surveys on geological maps and cross sections and the comparison between the direction and inclination of the cave survey data and the geometry of the massif discontinuities in three spatial dimensions 3 d the speleodisc method includes 1 collection and management of topographic information 2 collection and management of cave data 3 definition of the groups of conduits 4 elaboration of geological maps and cross sections 5 collection of discontinuity data bedding faults and joints 6 definition of groups of discontinuities and 7 comparison between the cave conduit groups and the families of discontinuities the speleodisc method allows us define the influence of the major and minor structures on the caves geometry estimating percentage of caves forced by each group of massif discontinuities and their intersections in 3 d nevertheless the speleodisc approach is mainly controlled by 1 the amount and quality of the cave survey data and 2 the abundance of cave deposits covering the conduit which can mask the original geometry

a steep fronted carboniferous carbonate platform clinoformal geometry and lithofacies picos de europa nw spain a steep margined carbonate platform is developed in the carboniferous synorogenic foreland basin of northern spain dips of 60 90 produced during late carboniferous thrusting enable cross sections of a 4 km wide portion of the marginal area of this platform las llacerias outcrop to be studied in aerial photographs at a seismic scale three stratal domains are observed 1 a horizontal bedded platform 2 a clinoformal bedded margin with a relief of up to 500 m and 3 a low angle toe of slope where slope beds interfinger with basin sediments the slope shows well bedded sigmoidal clinoforms with depositional dips ranging from 15 to 32 based on lithology and stratal patterns four facies groups have been recognized 1 a flat topped platform in which thick algal boundstone skeletal packstone grainstone and peloidal micrite wackestone with a poorly rhythmic character prevail 2 the platform margin and upper slope characterized by microbial boundstone spanning a bathymetric range of 150 m measured from the break of slope 3 a slope predominantly composed of margin derived rudstones and breccias and 4 a toe of slope to basin zone where a cyclic alternation of spiculitic siltstones packstone to grainstone calciturbidites and rudstone breccia is visible five successive stages of platform development are deduced 1 bashkirian flooding of the pre existing serpukhovian platform giving rise to the nucleation of a low angle ramp to the south east of the study area with microbial mud mound accumulations and breccias and calciturbidites on the margins 2 early moscovian an influx of siliciclastic sediment buried part of the platform and reduced the area of carbonate sedimentation 3 moscovian aggradation and progradation of the carbonate system produced an extensive steep margined and flat topped shallow water platform shelf system 4 latest moscovian earliest kasimovian drowning of the platform and 5 kasimovian covering of the platform by marly calcareous ramp sediments

karsys hydrogeological 3d modeling of alpine karst aquifers developed in geologically complex areas picos de europa national park spain karst aquifers are valuable groundwater resources whose management requires the use of functioning hydrogeological models the karsys approach provides an explicit 3d conceptual model of the geometry and the functioning of karst aquifers that has been successfully applied in swiss and slovenian aquifers in this work karsys is applied in a complex geological area the picos de europa national park spain the hydrogeological 3d model 500 km2 shows an alpine karst aquifer compartmentalized into 32 groundwater bodies dammed up by subvertical barriers creating elevated saturated zones water tables at 1153 m asl and lower ones water tables at 145 m asl the recharge is through 18 spring catchment areas the groundwater flows to the saturated zones pass through vertical to inclined trajectories and phreatic flows are oriented toward nw ne and n karsys can be applied to any geologically complex area at a regional scale although the geological structure should be simplified and the precision in some places is low nevertheless karsys helps to identify the hydrogeological behavior of karst areas and is a useful guide for future hydrogeological researches

sedimentary record of pleistocene paleodoline evolution in the ebro basin ne spain abstract pleistocene fluvial deposits of the ebro river in ne spain are widely affected by faults fractures and tilting of beds based on the lithological geometrical and textural features of these deposits seven architectural elements have been differentiated gravel bars gb gravel filled channels ch sheets and channel fill sands sb are the most common elements and together with less frequent overbank fines ff characterize a gravel dominated braided fluvial system gravel lobes gl that draw progressive unconformities and are laterally related to u shaped or basin form mud deposits sediment gravity flow deposits sg and sands with slumps and convolute bedding sgs are not typical architectural elements of braided fluvial environments and they are interpreted in this work as related to syn sedimentary deformation our research proves that deformation is due to dissolution of the underlying tertiary evaporites with genesis of dolines the development of these karst structures involved both subsidence and sudden collapses that affected previous fluvial sediments small depressions dolines generated that were progressively filled by syn sedimentary deformed detrital deposits a model for the evolution of the doline fills is purposed that envisages several stages 1 gravitational processes caused remobilisation of previous fluvial gravels that were dragged to the created depression 2 flooding of the depression and development of a backswamp area that was progressively filled by fine sediments and gravel lobes as a consequence of the overflow of nearby channels 3 gravel lobes draw progressive unconformities revealing several subsidence episodes related to dissolution dragging and compaction 4 non deformed fluvial facies at the top of the series mark the end of the karstification influence osl optically stimulated luminiscence ages the first from the terraces of the ebro river demonstrate that karst has developed in this area at least since the late pleistocene and that the dolines have been filled in throughout several thousand years this large span time of doline evolution without anthropogenic influence should be considered for a better planning and management in hazardous areas

unsteady saltation on mars abstract saltation is an important process on mars as it contributes to dust raising bedform dynamics and aeolian abrasion lander measurements and mesoscale meteorological models suggest that winds in the martian atmosphere rarely exceed the fluid threshold value that is necessary to aerodynamically initiate saltation a fact in stark contrast to the existence of dunes and ripples on the planet many of which are in an active state of migration in an attempt to reconcile these observations we perform an unsteady simulation with a simple turbulence model to calculate the saltation transport rate sinusoidal wind variations are imposed on the saltation layer the numerical simulations verify that gusty transport is one of the main manifestations of martian sediment transport events a formula for the saltation transport rate is reported q m u u it p where u and u it are the friction velocity and impact threshold friction velocity the power p varies in the range of 0 7 1 8 on mars and 1 5 on earth depending on the period and amplitude of the gusty inflow wind our results show that the law of martian and terrestrial transport rate are not universal and hence one should be cautious when trying to extrapolate existing terrestrial results to mars

a two species model of aeolian sand transport the transport of sand by wind results from the equilibrium between the erosion of grains dragged by the flow and the resulting slow down of the wind velocity the dynamical mechanisms governing the saturation of the sand flux are investigated theoretically we first demonstrate that previous models based on the assumption that all the grains have the same trajectory are either not self consistent or lead to unstable solutions a model based on a discrete number of states is derived which solves these problems two well defined species of grain appear which correspond to saltons high energy grains and reptons grains ejected from the sand bed by the impact of saltons they play specific roles the negative feedback of the transport on the wind is limited to the reptation layer while most of the transport is due to saltation the model is further simplified benefiting from the existence of these two species and the dependencies of the threshold velocity the saturated flux the aerodynamic roughness and the saturation length are derived and compared to experimental measurements

timing and structural evolution in the limb of an orocline the pisuerga carrion unit southern limb of the cantabrian orocline nw spain abstract oroclines are the largest scale folds on earth and the process of oroclinal formation is a key topic in tectonics however most studies of oroclines have focused on the hinge areas where the changes in strike and therefore the orocline shape are most obvious in this paper we investigate the deformation mechanisms the timing and the structural and tectonic evolution of the pisuerga carrion unit situated on the southern limb of the cantabrian orocline at the nw of the iberian peninsula the cantabrian orocline located in the variscan belt of western europe has been recently defined as a secondary orocline constraining kinematics and deformation timing our study in the pisuerga carrion unit reveals that an out of sequence thrust system developed and reactivated existing structures by a flexural slip mechanism that was diachronous with respect to oroclinal formation joint analysis of unconformity bounded rock sequences provide a late moscovian age for oroclinal initiation ca 308 ma at least locally additionally comparing those joint sets found in different series we quantify a minimum of 40 counterclockwise vertical axis rotation for the pisuerga carrion unit during the late pennsylvanian

modeling saltation intermittency 1 in order to investigate the intermittency of the aeolian saltation a saltation model forced with instantaneous velocity fields has been introduced in a large eddy simulation airflow model the coupled model is evaluated on a flat erodible surface under various wind conditions and soil particle size distribution it is first shown that the model is able to simulate a well developed saltation layer in equilibrium with the turbulent flow the main characteristics of the saltation layer and their sensitivity to wind conditions are in good agreement with previous data set then the saltation intermittency is visualized through the presence of blowing sand structures near the surface known as aeolian streamers this is the first time that such structures are reproduced numerically from a correlation analysis we confirm previous thoughts that these sand structures are a visual footprint of past turbulent eddies propagating in the surface boundary layer the streamers appear to be embedded in larger saltation structures with increasing wind conditions the spatial scales of these streamers change with wind conditions and soil particle size distribution this is explained by two mechanisms 1 the modification of eddy structures with the main characteristics of the saltation layer and 2 the reduction of saltating particle sensitivity to the near surface eddies with increasing wind condition and soil median particle diameter as the eddy lifetime decreases within the saltation layer and the particle response time increases respectively the standard deviation of the saltation flux associated to these saltation patterns represents about 10 to 20 of the mean saltation flux

3d modeling and monitoring of karst system as a base for its evaluation and utilization a case study from eastern serbia beljanica mountain in eastern serbia is a part of the carpathian balkan arch northern alpine branch it covers an area of about 300 km2 and consists mostly of jurassic and cretaceous limestones numerous surface karst features long caves and several large karstic springs located in beljanica s piedmont along the contact of karstic and non karstic rocks are all indicators of an intense karstification currently the large karstic water reserves of beljanica mountain are not properly utilized because of their distance from main consumers the objection by national water managers that the springs lack a stable and sufficient discharge particularly during recession periods due to its unpolluted and high quality water the area is a great prospect for future water supply and provides an opportunity for artificial regulation and for the design and implementation of specific tapping structures this paper includes an analysis of the created 3d arcgis model of karst interior and its correlation with historical and newly collected data of spring discharges and groundwater physico chemical characteristics the results of karst aquifer monitoring both quantitative and qualitative are linked with the results of extensive field geological and speleological survey of the upper non saturated part of the karst such as sinkholes pits and caves and with the investigation of the permanently saturated deeper part of the aquifer including the diving methods the model of karst interior is based on the data from the 69 caves 15 sinks and 1 682 dolines sinkholes surveyed the total length of the karst channels network calculated using the gis model and presented in a 3d environment is 647 km the catchment areas of five major springs that drain the areas are estimated to range from only 7 km2 malo vrelo spring to 124 km2 vrelo mlave spring the groundwater exploitable reserves of beljanica karst aquifer are estimated to be over 4 m3 s the waters are low mineralized unpolluted and have a great potential for water supply