gis analysis to assess landslide susceptibility in a fluvial basin of nw sicily italy abstract landslide hazard assessment effected by means of geostatistical methods is based on the analysis of the relationships between landslides and the spatial distributions of some instability factors frequently such analyses are based on landslide inventories in which each record represents the entire unstable area and is managed as a single instability landform in this research landslide susceptibility is evaluated through the study of a variety of instability landforms landslides scarps and areas uphill from crown the instability factors selected were bedrock lithology steepness topographic wetness index and stream power index the instability landform densities computed for all the factors which were arranged in unique condition unit allowed us to derive a total of three prediction images for each landslide typology the role of the instability factors and the effects generated by the use of different landforms were analyzed by means of a bivariate analysis of the relationships between factors and landslide density b predictive power validations of the prediction images based on a random partition strategy the test area was the iato river basin north western sicily whose slopes are moderately involved in flow and rotational slide landslides 219 and 28 respectively the area is mainly made up of the following complexes numidian flysch clays 19 1 terravecchia sandy clays 5 1 terravecchia clayey sands 3 0 3 and san cipirello marly clays 9 0 the steepness parameter shows the highest landslide density in the 11 19 class for both the typologies 8 1 even if the density distributions for rotational slides are right asymmetric and right shifted we obtained significant differences in shape when we used different instability landforms unlike scarps and areas uphill from crowns landslide areas produce left asymmetric and left shifted density distributions for both the typologies as far as the topographic wetness index is concerned much more pronounced differences were detected among the instability landforms of rotational slides in contrast the flow landslides produce normal like density distributions the latter and the rotational slide landslide areas produce the highest density values in the class 5 5 6 7 despite an abrupt decreasing trend starting from the first class 3 2 4 4 which is generated by the density values of the rotational slide scarps and areas uphill from crowns the stream power index at the foot of the slopes which was automatically derived using a gis procedure shows a positive correlation with the landslide densities marked by the maximum classes 4 8 6 0 for flows and 6 0 7 2 for rotational slides the validation procedure results confirmed that the choice of instability landform influences the results of the susceptibility analysis furthermore the validation procedure indicates that a the predictive models are generally satisfactory b scarps and zones uphill from crown areas are the most diagnostically unstable landforms for flow and rotational slide landslides respectively

evaluation of mining induced energy and rockburst prediction at a diamond mine in canada using a full 3d elastoplastic finite element model abstract rockburst occurs when a volume of rock is strained beyond its elastic limit this type of failure is violent and instantaneous its occurrence is a major concern for the safety of underground personnel this paper reviews the current methods of rockburst prediction then a methodology is proposed to assess the extent and magnitude of the mining induced strain energy and its accumulation in a rock mass to predict the rockburst potentials in an underground mine both conventional and numerical methods have been combined to estimate the rockburst potentials in a real case study mine a case study of canadian diamond mine has been used to implement the proposed methodology site investigations have been conducted by traveling several times to the mine site and gathering essential data such as in situ stress states mining methods the geometry of underground openings mining and stoping sequences and rock mass classification kimberlite samples from both pipes have been collected for rock mechanics laboratory tests finally using the results of the numerical model two rockburst criteria ts and bpi have been used to assess the rockburst tendency in the understudy domain utilizing the proposed methodology potentially hazardous areas can be identified

sedimentary pyrite formation an update sedimentary pyrite formation during early diagenesis is a major process for controlling the oxygen level of the atmosphere and the sulfate concentration in seawater over geologic time the amount of pyrite that may form in a sediment is limited by the rates of supply of decomposable organic matter dissolved sulfate and reactive detrital iron minerals organic matter appears to be the major control on pyrite formation in normal non euxinic terrigenous marine sediments where dissolved sulfate and iron minerals are abundant by contrast pyrite formation in non marine freshwater sediments is severely limited by low concentrations of sulfate and this characteristic can be used to distinguish ancient organic rich fresh water shales from marine shales under marine euxinic conditions sufficient h2s is produced that the dominant control on pyrite formation is the availability of reactive iron minerals calculations based on a sulfur isotope model indicate that over phanerozoic time the worldwide average organic carbon to pyrite sulfur ratio of sedimentary rocks has varied considerably high cs ratios during permo carboniferous time can be explained by a shift of major organic deposition from the oceans to the land which resulted in the formation of vast coal swamps at that time low cs ratios compared to today during the early paleozoic can be explained in terms of a greater abundance of euxinic basins combined with deposition of a more reactive type of organic matter in the remaining oxygenated portions of the ocean the latter could have been due to lower oceanic oxygen levels and or a lack of transportation of refractory terrestrial organic matter to the marine environment due to the absence of vascular land plants at that time

integrated biogeochemical and hydrologic processes driving arsenic release from shallow sediments to groundwaters of the mekong delta abstract arsenic is contaminating the groundwater of holocene aquifers throughout south and southeast asia to examine the biogeochemical and hydrological processes influencing dissolved concentrations and transport of as within soils sediments in the mekong river delta a 50 km2 field site was established near phnom penh cambodia where aqueous as concentrations are dangerously high and where groundwater retrieval for irrigation is minimal dissolved as concentrations vary spatially ranging up to 1300 g l in aquifer groundwater and up to 600 g l in surficial clay pore water groundwaters with high as concentrations are reducing with negligible dissolved o2 and high concentrations of fe ii nh 4 and dissolved organic c within near surface environments these conditions are most pronounced in sediments underlying permanent wetlands often found within oxbow channels near the mekong river there labile c co deposited with as bearing fe hydr oxides under reducing conditions drives the reductive mobilization inclusive of fe and as reduction of as here conditions are described under which as is mobilized from these sediments and near surface as release is linked to aquifer contamination over long time periods 100s to 1000s of years site biogeochemistry is coupled with extensive hydrologic measurements and accordingly a comprehensive interpretation of spatial as release and transport within a calibrated hydraulic flow field is provided of an as contaminated aquifer that is representative of those found throughout south and southeast asia

an equivalent discontinuous modeling method of jointed rock masses for dem simulation of mining induced rock movements abstract the discrete element method dem is of obvious and inherent advantages in simulating large displacements and discontinuous deformations of rock masses and thus is suitable to simulate the mining induced rock movements however when the region of the dem calculation model is large for example when both the length and width of the research area are larger than several hundreds of meters the rock mass in the model range often contains a large number of actual joints if the calculation model is built according to the distribution of the actual joints the calculation model of dem will consist of a large number of blocks which would lead to the impossibility of numerical calculations to address this problem an equivalent discontinuous modeling method edmm of jointed rock masses for dem simulation of mining induced rock movements is proposed in this paper in this method an actual geological body with a complex joint system will be simplified into an equivalent discontinuous model edm which is a dem calculation model with a simple hypothesis joint system the approach for determining the mechanical parameters i e the cohesive strength c the internal friction angle the joint normal stiffness jkn and the joint shear stiffness jks of the hypothetical joints of the edm is the core of the proposed edmm the main procedure of the proposed edmm is composed of 1 for each subarea of an edm building a group of equivalent discontinuous cube models edcms that are of different joint spacings 2 determining the joint mechanical parameters of each edcm based on the mechanical properties of the actual rock masses of the subarea 3 establishing the relationships between the joint spacings and joint mechanical parameters for each subarea of edm and 4 determining the mechanical parameters of the hypothesis joints in each subarea of the edm according to these relationships by exploiting the edm the dem numerical simulation is performed to simulate the mining induced rock movements and failures to demonstrate the applicability the proposed edmm was employed to simulate the rock movements and failures triggered by mining under the western open pit final slope of yanqianshan iron mine

evaluation of different machine learning models for predicting and mapping the susceptibility of gully erosion abstract gully erosion constitutes a serious problem for land degradation in a wide range of environments the main objective of this research was to compare the performance of seven state of the art machine learning models svm with four kernel types bp ann rf and brt to model the occurrence of gully erosion in the kashkan poldokhtar watershed iran in the first step a gully inventory map consisting of 65 gully polygons was prepared through field surveys three different sample data sets s1 s2 and s3 including both positive and negative cells 70 for training and 30 for validation were randomly prepared to evaluate the robustness of the models to model the gully erosion susceptibility 12 geo environmental factors were selected as predictors finally the goodness of fit and prediction skill of the models were evaluated by different criteria including efficiency percent kappa coefficient and the area under the roc curves auc in terms of accuracy the rf rbf svm brt and p svm models performed excellently both in the degree of fitting and in predictive performance auc values well above 0 9 which resulted in accurate predictions therefore these models can be used in other gully erosion studies as they are capable of rapidly producing accurate and robust gully erosion susceptibility maps gesms for decision making and soil and water management practices furthermore it was found that performance of rf and rbf svm for modelling gully erosion occurrence is quite stable when the learning and validation samples are changed

a procedure for landslide susceptibility zonation by the conditional analysis method numerous methods have been proposed for landslide probability zonation of the landscape by means of a geographic information system gis among the multivariate methods i e those methods which simultaneously take into account all the factors contributing to instability the conditional analysis method applied to a subdivision of the territory into unique condition units is particularly straightforward from a conceptual point of view and particularly suited to the use of a gis in fact working on the principle that future landslides are more likely to occur under those conditions which led to past instability landslide susceptibility is defined by computing the landslide density in correspondence with different combinations of instability factors the conceptual simplicity of this method however does not necessarily imply that it is simple to implement especially as it requires rather complex operations and a high number of gis commands moreover there is the possibility that in order to achieve satisfactory results the procedure has to be repeated a few times changing the factors or modifying the class subdivision to solve this problem we created a shell program which by combining the shell commands the gis geographical research analysis support system grass commands and the gawk language commands carries out the whole procedure automatically this makes the construction of a landslide susceptibility map easy and fast for large areas too and even when a high spatial resolution is adopted as shown by application of the procedure to the parma river basin in the italian northern apennines

distribution of local landforms at head and end points of gullies on different grid spacing abstract local landforms described by signs of curvatures can be considered as potential indicators of gully formation however the role of these landforms is not generally investigated in literature hence the goals of the present research are i identification of the relationships of land surface attributes at the head and end points of gullies with the size of these gullies at different grid spacings of a digital elevation model dem ii explanation of the frequency of occurrence fo of local landforms investigations were conducted on the example of 439 gullies of the hronska pahorkatina hill land in slovakia the sizes of the gullies were described by their area and perimeter altitude slope steepness maximal catchment area mca and curvatures were calculated at the head and end points of these gullies 12 types of main local landforms mllfs were identified by the signs of six curvatures for calculation of land surface attributes a set of dems with grid spacings at every 10 m interval from 10 m to 100 m was prepared at the head points of gullies significant spearman s rank correlation coefficients rs show that mca and curvatures related with gully size at dem grid spacings from 10 m to 30 m at the end points such relationships are observed at all grid spacings a negative rs between gully size and slope steepness is obtained at the head points it is demonstrated that the large gullies reached more flat locations in comparison with small gullies at the end points negative rs indicates that large gullies are characterized by flatter outlets in comparison with small gullies the fo of mllfs at the head and end points of gullies relative to their frequency for the whole dem indicate that only four types of mllf are systematically related to gully occurrence

a gis based approach for gully erosion susceptibility modelling a test in sicily italy the aim of this study is to analyze the susceptibility conditions to gully erosion phenomena in the magazzolo river basin and to test a method that allows for driving the factors selection the study area is one of the largest 225 km2 watershed of southern sicily and it is mostly characterized by gentle slopes carved into clayey and evaporitic sediments except for the northern sector where carbonatic rocks give rise to steep slopes in order to obtain a quantitative evaluation of gully erosion susceptibility statistical relationships between the spatial distributions of gullies affecting the area and a set of twelve environmental variables were analyzed stereoscopic analysis of aerial photographs dated 2000 and field surveys carried out in 2006 allowed us to map about a thousand landforms produced by linear water erosion processes classifiable as ephemeral and permanent gullies the linear density of the gullies computed on each of the factors classes was assumed as the function expressing the susceptibility level of the latter a 40 m digital elevation model dem prepared from 1 10 000 scale topographic maps was used to compute the values of nine topographic attributes primary slope aspect plan curvature profile curvature general curvature tangential curvature secondary stream power index topographic wetness index ls usle factor from available thematic maps and field checks three other physical attributes lithology soil texture land use were derived for each of these variables a 40 m grid layer was generated reclassifying the topographic variables according to their standard deviation values in order to evaluate the controlling role of the selected predictive variables one variable susceptibility models based on the spatial relationships between each single factor and gullies were produced and submitted to a validation procedure the latter was carried out by evaluating the predictive performance of models trained on one half of the landform archive and tested on the other large differences of accuracy were verified by computing geometric indexes of the validation curves prediction and success rate curves roc curves drawn for each one variable model in particular soil texture general curvature and aspect demonstrated a weak or a null influence on the spatial distribution of gullies within the studied area while on the contrary tangential curvature stream power index and plan curvature showed high predictive skills hence predictive models were produced on a multi variable basis by variously combining the one variable models the validation of the multi variables models which generally indicated quite satisfactory results were used as a sensitivity analysis tool to evaluate differences in the prediction results produced by changing the set of combined physical attributes the sensitivity analysis pointed out that by increasing the number of combined environmental variables an improvement of the susceptibility assessment is produced this is true with the exception of adding to the multi variables models a variable as slope aspect not correlated to the target variable the addition of this attribute produces effects on the validation curves that are not distinguishable from noise and as a consequence the slope aspect was excluded from the final multi variables model used to draw the gully erosion susceptibility map of the magazzolo river basin in conclusion the research showed that the validation of one variable models can be used as a tool for selecting factors to be combined to prepare the best performing multi variables gully erosion susceptibility model

badland susceptibility assessment in volterra municipality tuscany italy by means of gis and statistical analysis badlands can be defined as complex and peculiar types of erosional formations that develop in clayey environments and are mainly favoured by lithological and topographic features as well as by markedly seasonal climate this work aims at assessing badland susceptibility in volterra municipality located in tuscany region italy by means of bivariate statistical analysis implemented in a geographic information system the volterra municipality is affected by intense soil erosion processes including rill and gully erosion usually turned out as badland forms mostly occurring on pliocene pleistocene clayey sediments firstly an inventory of 234 badland areas was produced on the basis of an available pre existing database integrated with the interpretation of aerial photographs and supported by a field survey badlands were distinguished in type a and type b according to different evolutional stage vegetation presence and consequently different landforms then nine geoenvironmental factors supposed to be predisposing for badland occurrence were chosen and combined with the spatial frequency of badland areas derived from the inventory through information value statistic approach the result was a badland susceptibility map that highlights a strong control of lithology slope gradient and land use in conditioning badland development in the investigated area the effectiveness of the performed model was demonstrated by a validation test computed through a receiver operating characteristics analysis the outcomes of this work provide an updated badland database that is useful for soil erosion management and further land use planning within the volterra municipality

sediment yield and erosion rate estimation in the mountain catchments of the camastra artificial reservoir southern italy a comparison between different empirical methods abstract the sedimentary budget assessment is an important topic for the scientific and social community because it is crucial to understand the dynamics of orogenic belts and cope with a number of practical problems such as soil conservation and sediment accumulation in reservoir sediment yield or denudation rate estimates in southern central italy are generally obtained either by applying simple empirical relationships based on the statistical regression between the geomorphic parameters of the drainage network and the suspended sediment yield measured at the drainage basins outlets or by using qualitative quantitative sediment delivery ratio or erosion models in this work we carry out a study of catchment dynamics and a sedimentary yield computation of several mountain catchments of the central western sector of the basilicata region southern italy which are located upstream of an artificial reservoir the sediment yield and erosion rate have been computed through both an indirect assessment of the suspended sediment yield based on the tu index mean annual suspension sediment yield and the application of the rusle and usped empirical methods the results obtained have been compared with the historical data of sediment accumulation measured in the artificial reservoir of the camastra dam where a detailed evaluation of the volumes of historical i e about 40 years sediment storage was collected the collected dataset represents a basic tool both for the investigation of the morpho dynamics of a typical mountain catchment of the mediterranean area and the evaluation of sediment budget related to fluvial and hillslope processes the 38 year long record of the sediment storage in the camastra artificial reservoir located at the outlet of the studied mountain catchments permits the validation of empirical relationships based on the geomorphic and climatic parameters of the drainage basin among the three different methods of sediment yield evaluation tu index rusle and usped the tu index showed the best prediction ability although usped erosion model also furnished a good estimation as also confirmed by other works the indirect estimation of sediment yield based on ciccacci s empirical relationships can represent a good proxy of short term denudation rates in the mediterranean areas with geological and geomorphological features similar to the study area but the use of empirical models with increasing complexity such as the usped erosion model can help to explore the spatial distribution of the sediment yield sectors of the drainage basin the erosion hot spots and the role of landslides in sediment mobilization and hillslope channel connectivity processes

an integrated approach for the prediction of subsidence for coal mining basins abstract in this study land subsidence caused by underground mining activities was investigated by means of a new subsidence prediction approach isp tech which takes into account the most important parameters contributing subsidence development such as coal production methods depth mining sequence and other geomechanical characteristics of underground rock strata etc isp tech can be applied to operating mines to keep land subsidence under control as well as virgin coal sites to predict surface subsidence prior to mining activities in the method geological information gathered from the geographic information system gis and the mining information system mis are utilised to obtain geological cross sections which are used in finite element models for mesh building then a number of two dimensional finite element modelling analyses are carried out to determine land subsidence occurring due to mining operations finally land subsidence predicted from modelling studies is compared to the gps and or differential interferometry synthetic aperture radar din sar measurements if incompatibility of the results is detected finite element meshes should be optimised and then reanalysed to obtain more compatible results in the study two different case studies were given as examples of the application of isp tech results of the case studies showed that isp tech can successfully be applied to complex mine subsidence problems the proposed approach gives more accurate results than those obtained from other classical subsidence prediction methods

assessment of calanchi and rill interrill erosion susceptibilities using terrain analysis and geostochastics a case study in the oltrepo pavese northern apennines italy

predicting gully occurrence at watershed scale comparing topographic indices and multivariate statistical models abstract in this study the ability of five topographic indices to predict the gully trajectories observed in two adjacent watersheds located in sicily italy was evaluated two of these indices named mspi and mtwi as far as we know have never been employed to this aim they were obtained by multiplying the stream power index spi and the topographic wetness index twi respectively by the convergence index ci the predictive ability of the topographic indices was measured by using both cut off independent auc area under the receiver operating characteristic curve and dependent statistics cohen s kappa index sensitivity specificity these statistics were calculated also for 100 mars multivariate adaptive regression splines and 100 lr logistic regression model runs which used as predictors the topographic variables i e contributing area slope steepness plan curvature and convergence index combined into the five indices performance statistics of both topographic indices and statistical models were calculated using 100 random samples of 2 m grid cells which were extracted only from flow concentration lines this was done in order to focus the validation process on where gully erosion is more likely to occur mspi achieved the best predictive skill auc 0 93 0 71 among the topographic indices and exhibited similar and better accuracy than local i e trained and validated in the same watershed and transferred i e trained in one watershed and tested in the other one lr models respectively on the other hand mspi performed similarly to transferred mars runs auc 0 92 0 71 but slightly worse than local mars runs auc 0 95 0 77 based on the results of this experiment it can be inferred that i including ci helps in detecting hollow areas where gullies are more likely to occur and ii mpsi can be a valid alternative to a data driven approach for mapping gully erosion susceptibility in areas where a gully inventory is not available which is necessary to calibrate statistical models

application of the egem model to predict ephemeral gully erosion in sicily italy abstract recent research has shown the importance of ephemeral gully eg erosion in the context of global erosion and at the same time the lack of adequate models to estimate it at present the ephemeral gully erosion model egem is the only conceptual model specifically developed for ephemeral gully erosion estimation the main aim of the paper is to evaluate the performance of egem model adapted to local conditions compared with that of simple empirical equations a data set of 92 ephemeral gullies formed between 1995 and 2000 in a wheat cultivated study area in sicily italy was used for the purpose in order to improve egem performance two important adaptations were made both the rain distribution type and the causative rainfall of the hydrological component of egem were modified to reproduce local conditions the egem assumption of a constant depth for the entire length of the ephemeral gully was also modified egem performance was tested with two different rain distribution types three different causative rainfalls and two different eg depths the adaptation of the egem hydrological component improves the volume prediction with respect to the standard version of egem the improvement is mainly due to the rain distribution type whereas causative rainfall seems to be less important the use of adjusted eg depths is however essential to minimise the errors between measured and predicted volumes the capability of egem to predict the ephemeral gully cross section is weak and non significant relationships were found between measured and estimated width a regression analysis between ephemeral gully eroded volume and different morphological topographical and hydrological parameters confirms the great importance of eg length to explain eroded volume r 2 0 64 for the simple correlation between volume and length considering that the adaptation of the hydrological component and the measurement of eg depths are necessary for the eg volumes estimated by egem to be reliable it seems more simple as suggested by other authors to use empirical relations between eroded volume and length performed in different environments until more precise physically based models are developed

dynamic and static models of gully erosion abstract the main causes of gully formation are anthropogenic factors the clearing of native forests tilling of fallow lands and associated change of the hydrological conditions in the rainfall runoff system gully channels formation is very rapid during the period of gully initiation when morphological characteristics of a gully length depth width area and volume are far from stable this period is relatively short about 5 of a gully s lifetime for the most part of a gully s lifetime its size is near stable maximum value these two stages of gully development led to two types of gully erosion models 1 dynamic models to predict rapid changes of gully morphology at the first period of gully development 2 static models to calculate final morphometric parameters of stable gullies the dynamic gully model is based on the solution of the equations of mass conservation and gully bed deformation the model of straight slope stability was used for prediction of gully side walls inclination the static gully model is based on the assumption of final morphological equilibrium of a gully when averaged for several years elevations and width of gully bottom do not change this stability is associated with a negligible rate both of erosion and sedimentation at the gully bottom it means that flow velocity is less than the threshold value for erosion initiation but is more than the critical velocity of wash load sedimentation the dynamic and static gully models were verified on the data on gullies morphology and dynamics from yamal peninsula russia and new south wales australia

three dimensional variations in extensional fault shape and basin form the cache valley basin eastern basin and range province united states seismic reflection profiles drill hole data and geologic maps delimit the form of normal faults and tertiary sedimentary rocks in the southern half of the cache valley basin in northern utah dips of faults and sedimentary rocks were estimated from time migrated reflection profiles by using the stacking velocities for the data at the southern end of the basin the east cache fault zone is listric it shows 50 w dips near the surface and 20 w dips at depth the fault zone has been the site of 5 6 km of net dip slip tertiary rocks dip 18 e 25 e and exhibit a rollover geometry above the fault zone no faults are interpreted on the western side of the basin in the central part of the basin in utah the east cache fault is a single fault that dips at least 45 w near the surface and is the site of 4 5 6 4 km of net dip slip here the basin is bounded to the west by the west cache fault which is the site of at least 1 km of net slip that increases northward to 2 km of net slip slip on the east cache fault resulted in planar east dipping older tertiary rocks near the bottom of the basin younger tertiary strata with southwest west and northwest dips reflect complex tilting due to slip on the west and east cache faults anticlines in the tertiary basin fill deposits are present in the central part of the basin and may reflect changes in normal fault geometry at depth northward dip slip on the east cache fault zone decreases to 2 5 km the basin is broad shallow and filled with nearly flat lying tertiary rocks this area near the north south midpoint of the basin is bounded by the west and east cache faults but slip on the west cache fault appears to diminish northward a north trending reflection profile tied to both drill hole data and the east trending seismic profiles indicates that the basin is deeper in the southern end the along strike changes in fault geometry the amount of fault slip the subsurface form of the basin filling sedimentary rocks and the form of the basin indicate a complex history of faulting and deposition during its formation this study and other recent ones from the basin and range province indicate that such complexities may be typical of many tertiary basins in the region

empirical investigation and characterization of surface subsidence related to block cave mining abstract for guidance on relationships between caving depth and surface subsidence a comprehensive database was developed after an exhaustive search of published data from cave mining operations from around the world the distribution of data was found to largely focus on caving angles and macro deformations very little empirical data exists on the extent and magnitudes of smaller surface displacements the data clearly show that caving induced surface deformations tend to be discontinuous and asymmetric due to large movements around the cave controlled by geologic structures rock mass heterogeneity and topographic effects the data also show that as undercut depth increases for a given extraction volume the magnitude and extent of the caved zone on surface decreases however numerical modeling indicates that this is only the case for macro deformations and the extent of smaller displacements actually increases as a function of undercut depth the results presented caution against relying on existing empirical design charts for estimates of caving induced subsidence where small strain subsidence is of concern as the data being relied upon does not properly extrapolate beyond the macro deformations i e caving angles that make up the majority of the observations the findings also suggest that the extent and magnitudes of subsidence may be underestimated if the analysis adopted neglects the influence of geological structures and assumes symmetrical surface displacements above the undercut

morphometric and hydraulic geometry assessment of a gully in sw spain abstract gully erosion represents one of the most significant types of land degradation in the mediterranean areas giving place to important on and off site effects in this paper a second order gully located in sw spain is analyzed along the gully 28 cross sections were established and measured with a leica tcrm1102 laser total station approximately every 6 months from 2001 to 2007 the sections were located at variable distance placing them in areas where active erosion was evident in total 13 field measurements were carried out and the geometric characteristics of 28 cross sections were obtained morphometric analyses were carried out in both the main gully and a tributary reach by applying an empirical relationship between channel length and eroded volume morphometric variables of the gully sections were combined into two dimensionless groups and a morphological similarity between different linear erosion landforms rills ephemeral and permanent gullies was obtained then the coefficient of variation of the calculated volumes was used to compare the instability between the main gully and the tributary reach finally the hydraulic geometry of the gully was assessed by calibrating three empirical power equations which relate bankfull discharge with mean flow velocity cross sectional depth and width the hydraulic characterization of the main gully and the tributary reach was investigated for each field survey and a different behavior was detected the hydraulic analysis also demonstrated that higher values of discharge provide better predictions of flow velocity the size of the main and tributary gullies affects the discharge width relationship and that gully depth is the variable which can be predicted with the highest accuracy

impact of ground surface subsidence due to underground mining on surface infrastructure the case of the anomaly no 12 sechahun iran ground surface subsidence as the result of the application of caving methods block caving sublevel caving and longwall mining may leave significant impact on surface infrastructures which are located in subsidence influence zone the anomaly no 12 sechahun located in 32 km from bafq in yazd province iran was planned to be extracted by sublevel caving method evaluating the amount of surface subsidence in this mine was very important because different surface infrastructures railway road natural gas transmission pipeline and water pipeline and an open pit mine anomaly no 10 are located within the mining area the main purpose of this research was to evaluate the effect of surface subsidence due to underground iron mine anomaly no 12 sechahun on surface infrastructures through numerical and empirical methods for this purpose first the subsidence parameters such as caving angle subsidence angle and the influence zone were estimated by empirical methods then numerical modeling was applied to estimate rock mass properties joint mapping was taken from the site at anomaly no 10 and a set of numerical models were employed through a discrete fracture network in 3dec software to determine representative elemental volume the flac3d software was used to simulate the ground surface subsidence due to sublevel caving method then the longitudinal and transverse profiles of subsidence and the influence zone were studied the results show that surface infrastructures which are located in subsidence influence zone should be moved to 2 3 km from the orebody deposit center however the results of this study still must be validated by engineering monitoring data

a review of the source behaviour and distribution of arsenic in natural waters the range of as concentrations found in natural waters is large ranging from less than 0 5 g l 1 to more than 5000 g l 1 typical concentrations in freshwater are less than 10 g l 1 and frequently less than 1 g l 1 rarely much higher concentrations are found particularly in groundwater in such areas more than 10 of wells may be affected defined as those exceeding 50 g l 1 and in the worst cases this figure may exceed 90 well known high as groundwater areas have been found in argentina chile mexico china and hungary and more recently in west bengal india bangladesh and vietnam the scale of the problem in terms of population exposed to high as concentrations is greatest in the bengal basin with more than 40 million people drinking water containing excessive as these large scale natural as groundwater problem areas tend to be found in two types of environment firstly inland or closed basins in arid or semi arid areas and secondly strongly reducing aquifers often derived from alluvium both environments tend to contain geologically young sediments and to be in flat low lying areas where groundwater flow is sluggish historically these are poorly flushed aquifers and any as released from the sediments following burial has been able to accumulate in the groundwater arsenic rich groundwaters are also found in geothermal areas and on a more localised scale in areas of mining activity and where oxidation of sulphide minerals has occurred the as content of the aquifer materials in major problem aquifers does not appear to be exceptionally high being normally in the range 1 20 mg kg 1 there appear to be two distinct triggers that can lead to the release of as on a large scale the first is the development of high ph 8 5 conditions in semi arid or arid environments usually as a result of the combined effects of mineral weathering and high evaporation rates this ph change leads either to the desorption of adsorbed as especially as v species and a range of other anion forming elements v b f mo se and u from mineral oxides especially fe oxides or it prevents them from being adsorbed the second trigger is the development of strongly reducing conditions at near neutral ph values leading to the desorption of as from mineral oxides and to the reductive dissolution of fe and mn oxides also leading to as release iron ii and as iii are relatively abundant in these groundwaters and so4 concentrations are small typically 1 mg l 1 or less large concentrations of phosphate bicarbonate silicate and possibly organic matter can enhance the desorption of as because of competition for adsorption sites a characteristic feature of high groundwater as areas is the large degree of spatial variability in as concentrations in the groundwaters this means that it may be difficult or impossible to predict reliably the likely concentration of as in a particular well from the results of neighbouring wells and means that there is little alternative but to analyse each well arsenic affected aquifers are restricted to certain environments and appear to be the exception rather than the rule in most aquifers the majority of wells are likely to be unaffected even when for example they contain high concentrations of dissolved fe

genesis and geomorphic evolution of the velke pinky stopes in the zlatohorska highlands eastern sudetes montanogenic landforms are commonly viewed as hazards by society but they are also holders of specific and uncommon morphology with unique dynamics that act as remarks on landscape history the velke pinky stopes in the zlatohorska highlands eastern sudetes are naturally revitalized post mining landforms with long term geoecological succession their genetic origin is diverse but recent processes such as deep seated slope deformations rockfalls and ground subsidence have resulted in a distinct morphology dominated by rock walls and the accumulation of blocks and debris wedges this morphology predisposes the stopes to become the core area of the most recent dynamic geomorphic activity within the wider relatively homogenous area by dendrogeomorphic techniques we identified more than 20 rockfall events within three of the stopes with increased activity since the 1980s only the 1991 and 2006 events were identical for all three stopes we obtained the years of exposures from 10 roots revealing the ground subsidence and opening of tension cracks or even the lateral retreat of the flanks of minor depressions the schmidt hammer test revealed the most recent and fresh gravitational activity in one of the stopes a relationship between the superficial morphology and underground structure was proven by electrical resistivity profiling compared to the previous studies engaged with the abandoned mines we presented how complex their evolution can be our study brings new information about the historical development of anthropogenic relief forms moreover our results suggest that standard research approaches can be successfully applied for development analysis of these specific forms

water erosion susceptibility mapping by applying stochastic gradient treeboost to the imera meridionale river basin sicily italy abstract soil erosion by water constitutes a serious problem affecting various countries in the last few years a number of studies have adopted statistical approaches for erosion susceptibility zonation in this study the stochastic gradient treeboost sgt was tested as a multivariate statistical tool for exploring analyzing and predicting the spatial occurrence of rill interrill erosion and gully erosion this technique implements the stochastic gradient boosting algorithm with a tree based method the study area is a 9 5 km 2 river catchment located in central northern sicily italy where water erosion processes are prevalent and affect the agricultural productivity of local communities in order to model soil erosion by water the spatial distribution of landforms due to rill interrill and gully erosion was mapped and 12 environmental variables were selected as predictors four calibration and four validation subsets were obtained by randomly extracting sets of negative cases both for rill interrill erosion and gully erosion models the results of validation based on receiving operating characteristic roc curves showed excellent to outstanding accuracies of the models and thus a high prediction skill moreover sgt allowed us to explore the relationships between erosion landforms and predictors a different suite of predictor variables was found to be important for the two models elevation aspect landform classification and land use are the main controlling factors for rill interrill erosion whilst the stream power index plan curvature and the topographic wetness index were the most important independent variables for gullies finally an roc plot analysis made it possible to define a threshold value to classify cells according to the presence absence of the two erosion processes hence by heuristically combining the resulting rill interrill erosion and gully erosion susceptibility maps an integrated water erosion susceptibility map was created the adopted method offers the advantages of an objective and repeatable procedure whose result is useful for local administrators to identify the areas that are most susceptible to water erosion and best allocate resources for soil conservation strategies

speciation and behavior of arsenic in evaporation basins california usa disposal of saline subsurface drainage waters from croplands into evaporation basins or ponds in the san joaquin valley of california causes excessive accumulation of salts and elevated concentrations of arsenic as a potentially high risk element with little information about its fate in the agricultural evaporation ponds we examined dissolved as concentration speciation and distribution in waters as well as as fractionation in sediments in the 10 cell south evaporation basin for better understanding of processes and conditions affecting as transformations and fate in a specific drainage disposal facility the increase of total dissolved as concentrations were observed with higher cl and electric conductivity along flow path indicating that evaporation was an important factor regulating total dissolved as concentration the increases of reduced as species such as arsenite as iii and organic as monomethylarsonic acid and dimethylarsinic acid were found towards the terminal flow pathway however arsenate as v the oxidized species remained greater than 67 of total dissolved as in all cell waters sequential extractions of sediments indicated that reducing conditions may influence as behavior in sediments to be more soluble and exchangeable arsenic association with oxides was appreciable only under oxidizing condition carbonate minerals played an important role in immobilizing as into the sediments under alkaline condition and a broad range of redox conditions however these sink mechanisms did not significantly reduce as concentrations in the cell waters the reducing condition facilitated by high concentration of organic matter might be a major factor for the increase in as mobility

numerical analysis and prediction of ground surface movement induced by coal mining and subsequent groundwater flooding abstract ground surface movement shows different features during mining and post mining period if the mine goaf is dry surface subsidence is observed in both periods if the mine goaf is flooded by groundwater however ground surface uplift can be observed although much smaller in amplitude compared to the preceding subsidence a numerical modeling strategy is proposed to predict uplift during the flooding process of an excavated coal mining area under complex geological conditions the modeling approach considers three phases virgin state before mining stage immediately after mine closure flooding phase the model considers elasto plastic material behavior including faults represented by interfaces in situ measurements are used for calibration of the model the oelsnitz abandoned coal mine is used for model validation and prediction the measured subsidences up to 17 m were reproduced as well as the uplift within the last 10 years with values between 0 5 2 0 mm year spatial distribution of uplift areas is well reproduced predictions up to the year 2051 show an increase in uplift velocity between 0 5 3 0 mm year and additional total uplift of up to 300 mm

comparing models of debris flow susceptibility in the alpine environment abstract debris flows are widespread in val di fassa trento province eastern italian alps where they constitute one of the most dangerous gravity induced surface processes from a large set of environmental characteristics and a detailed inventory of debris flows we developed five models to predict location of debris flow source areas the models differ in approach statistical vs physically based and type of terrain unit of reference slope unit vs grid cell in the statistical models a mix of several environmental factors classified areas with different debris flow susceptibility however the factors that exert a strong discriminant power reduce to conditions of high slope gradient pasture or no vegetation cover availability of detrital material and active erosional processes since slope and land use are also used in the physically based approach all model results are largely controlled by the same leading variables overlaying susceptibility maps produced by the different methods statistical vs physically based for the same terrain unit of reference grid cell reveals a large difference nearly 25 spatial mismatch the spatial discrepancy exceeds 30 for susceptibility maps generated by the same method discriminant analysis but different terrain units slope unit vs grid cell the size of the terrain unit also led to different susceptibility maps almost 20 spatial mismatch maps based on different statistical tools discriminant analysis vs logistic regression differed least less than 10 hence method and terrain unit proved to be equally important in mapping susceptibility model performance was evaluated from the percentages of terrain units that each model correctly classifies the number of debris flow falling within the area classified as unstable by each model and through the metric of roc curves although all techniques implemented yielded results essentially comparable the discriminant model based on the partition of the study area into small slope units may constitute the most suitable approach to regional debris flow assessment in the alpine environment

assessing the susceptibility to water induced soil erosion using a geomorphological bivariate statistics based approach the aim of this study was the assessment at basin scale of the susceptibility to water induced soil erosion processes i e gully erosion and sheet rill erosion using geomorphological analysis geographical information systems gis and bivariate statistics the study was carried out in a watershed located in southern italy a detailed analysis of the pre existing literature led to select lithology land use slope angle and slope aspect as soil erosion determining factors dfs as they are non redundant and affect both the soil forming processes that control soil erodibility and the erosive power of running waters water produced erosional landforms such as gullies and areas severely affected by sheet rill erosion were surveyed and mapped using classical techniques of geomorphological analysis the gis processing of the geomorphological data allowed calculating the areal density of these landforms in each df class weighting values wi corresponding to the susceptibility level of each df class were calculated using bivariate statistics finally gis overlay procedures of the thematic maps previously reclassified on the basis of the calculated wi allowed to produce two susceptibility maps i e gully erosion and sheet and or rill erosion susceptibility map the soil geomorphological coherence of the produced results has been checked and widely discussed in the framework of the pre existing literature both the geomorphological coherence of the calculated wi and the results of the validation procedure suggested a good reliability of the method which is also relatively easy to apply and update

use of terrain variables for mapping gully erosion susceptibility in lebanon this paper predicts the geographic distribution and size of gullies across central lebanon using a geographic information system gis and terrain analysis eleven primary elevation upslope contributing area aspect slope plan profile and tangential curvature flow direction flow width flow path length rate of change of specific catchment area along the direction of flow and three secondary steady state quasi dynamic topographic wetness sediment transport capacity topographic variables were generated and used along with digital data collected from other sources soil geology to statistically explain gully erosion field measurements three tree based regression models were developed using 1 all variables 2 primary topographic variables only and 3 different pairs of variables the best regression tree model combined the steady state topographic wetness and sediment transport capacity indices and explained 80 of the variability in field gully measurements this model proved to be simple quick realistic and practical and it can be applied to other areas of the mediterranean region with similar environmental conditions thereby providing a tool to help with the implementation of plans for soil conservation and sustainable management copyright 2007 john wiley sons ltd

factors controlling as and u in shallow ground water southern carson desert nevada abstract unusually high as and u concentrations 100 g l are widespread in shallow ground water beneath the southern carson desert the high concentrations which locally exceed 1000 g l are of concern from a human health standpoint because the shallow ground water is used for domestic supply possible affects on wildlife are also of concern because the ground water flows into shallow lakes and marshes within wildlife refuges arsenic and u concentrations in ground water of the southern carson desert appear to be affected by evaporative concentration redox reactions and adsorption the relation of these elements with cl suggest that most of the high concentrations can be attributed to evaporative concentration of carson river water the primary source of recharge some ground water contains higher as and u concentrations that cannot be explained by evaporative concentration alone oxidation reduction reactions involving metal oxides and sedimentary organic matter appear to contribute as u inorganic c fe and mn to the ground water arsenic in fe oxide was confirmed by chemical extraction and is consistent with laboratory adsorption studies uranium in both sedimentary organic c and fe oxide coatings has been confirmed by fission tracks and petrographic examination arsenic concentrations in the ground water and chemical extracts of aquifer sediments are broadly consistent with adsorption as a control on some dissolved as concentrations an apparent loss of as from some ground water as evaporative concentration proceeds is consistent with adsorption as a control on as however evidence for adsorption should be viewed with caution because the adsorption model used values for the adsorbent that have not been shown to be valid for the aquifer sediments throughout the southern carson desert hydrologic and geochemical conditions in the carson desert are similar to other areas with high as and u concentrations in ground water including the salton sea basin and southern san joaquin valley of california hydrologic and geochemical conditions that produced some sandstone type u ore deposits including those in the non marine closed basin sediments of the morrison formation near grants new mexico suggest that the carson desert may be a modern analog for those systems

solid phases and desorption processes of arsenic within bangladesh sediments abstract arsenic is a contaminant in the groundwater of bangladesh and west bengal india where an estimated 57 million people may be drinking water with unsafe arsenic levels the source of arsenic appears to be natural solid phase arsenic in the sediments and various theories have been put forth regarding the modes of arsenic release ranging from the oxidative or reductive degradation of arsenic bearing solids to competitive ligand displacement by phosphate currently however reductive dissolution of fe iii hydr oxides and concomitant arsenic release is the most widely accepted explanation of high arsenic groundwater concentrations using micro x ray fluorescence elemental mapping and micro x ray absorption near edge structure spectroscopy we detect arsenic bearing sulfides in the aquifer sediments from our field site in munshiganj bangladesh reduction of fe and as in surface soil layers is apparent but fe iii hydr oxides are not detected in the holocene aquifer materials rapid abiotic desorption of arsenic from sediments is observed in batch experiments and positive controls with ferrihydrite dismiss the role of ferric hydr oxides in arsenic retention within the aquifer sediments based on our laboratory results we do not see evidence for ferric hydr oxide reductive dissolution at well depths in the holocene aquifer in contrast our data suggest that arsenic is only released via redox cycling in surface soils sediments and thus must then be transported to well depth through the sandy aquifer

surface collapse control under thick unconsolidated layers by backfilling strip mining in coal mines abstract surface subsidence induced by mineral extraction from underground mines can significantly affect the ecological environment and human life surface collapse is extremely hazardous and typically occurs without warning in china numerous surface collapses have occurred during mining operations in coal mines located under thick unconsolidated layers via analysis of the stability of the bearing structure arch structure in unconsolidated layers and key strata in rock strata based on their effects on strata movement our study reveals the formation mechanism of surface collapses and the roles played by two critical parameters mining length and mining height it is speculated that the bearing structure cannot be self stable and will collapse during longwall mining with increasing mining length and mining height as a result the ground surface will collapse on the longwall face gob accompanied by the failure of the bearing structure with these risks in mind this study proposes a backfilling strip mining method via determination of the appropriate longwall face length and mining height to guard against bearing structure failure and thus avoid surface collapse a field trial of the technique was conducted at a suitable chinese coal mine located under thick unconsolidated layers the maximum surface subsidence observed was only 0 369 m which is 92 less than the subsidence in longwall face lw 3a04 no surface collapse occurred during the mining process thus our results indicate that the proposed technique can successfully prevent surface collapse during longwall mining under thick unconsolidated layers

geochemistry of aquifer sediments and arsenic rich groundwaters from kandal province cambodia abstract elevated as is well known to be present in aquifers utilised for drinking water and irrigation in west bengal and bangladesh this problem has also more recently been discovered in other parts of asia including vietnam cambodia inner mongolia and the middle ganges plain analysis of groundwaters in kandal province of cambodia found waters with comparable geochemistry to the as rich groundwaters of the west bengali delta similarities included high but heterogeneous as distributions predominantly in the form as iii high fe moderate to high hco 3 circumneutral ph low so 4 2 and geochemical components indicative of reducing conditions good positive correlations between as fe hco 3 and nh 4 and dissolved organic c is consistent with as release predominantly via microbially mediated reductive dissolution of as bearing fe iii oxides further evidence for such a process is found from correlations between as fe and organic matter from analysis of aquifer sediments by the presence of goethite in the finer fractions and from the association of as with amorphous poorly crystalline and well crystallised hydrous fe oxides the presence of several high as but low fe wells implies that microbes could have a more direct role in mediating as release via the direct utilisation of fe iii or as v as electron acceptors the presence of elevated as in waters with short aquifer residence times as indicated by their geochemical signature highlights the possible vulnerability of these aquifers to the influx of surface derived waters providing an additional source of labile organic c that could exacerbate as release by stimulating microbial activity

mapping accumulated mine subsidence using small stack of sar differential interferograms in the southern coalfield of new south wales australia the southern coalfield is located in the sydney basin in the state of new south wales nsw australia the coal seams of the southern coalfield contain high quality hard coking coals which are mostly used for steel production this paper describes an approach developed to study the subsidence associated with underground coal mining activity in the west cliff colliery in the southern coalfield of nsw using multiple sar differential interferograms accumulated subsidence maps have been derived using the approach within the study area results obtained by processing ten 10 alos palsar images showed that the land surface had subsided by more than 700 mm in the area of west cliff colliery longwall 32 during the period of image acquisitions june 2007 to october 2008 the results have been compared with deformation predicted by modelling as well as with the available gps field survey data high correlation has been observed between the dinsar derived subsidence results and the predicted mining induced deformation by comparing the dinsar measured subsidence with the gps derived results between september 2007 and march 2008 the magnitude and trend of the deformation has been confirmed the absolute differences range from 0 to 45 mm with a standard deviation of 8 mm and an average absolute difference of 12 mm

predicting the susceptibility to gully initiation in data poor regions permanent gullies are common features in many landscapes and quite often they represent the dominant soil erosion process once a gully has initiated field evidence shows that gully channel formation and headcut migration rapidly occur in order to prevent the undesired effects of gullying there is a need to predict the places where new gullies might initiate from detailed field measurements studies have demonstrated strong inverse relationships between slope gradient of the soil surface s and drainage area a at the point of channel initiation across catchments in different climatic and morphological environments such slope area thresholds s a can be used to predict locations in the landscape where gullies might initiate however acquiring s a requires detailed field investigations and accurate high resolution digital elevation data which are usually difficult to acquire to circumvent this issue we propose a two step method that uses published s a thresholds and a logistic regression analysis lr s a thresholds from the literature are used as proxies of field measurement the method is calibrated and validated on a watershed close to the town of algiers northern algeria where gully erosion affects most of the slopes the gullies extend up to several kilometres in length and cover 16 of the study area first we reconstruct the initiation areas of the existing gullies by applying s a thresholds for similar environments then using the initiation area map as the dependent variable with combinations of topographic and lithological predictor variables we calibrate several lr models it provides relevant results in terms of statistical reliability prediction performance and geomorphological significance this method using s a thresholds with data driven assessment methods like lr proves to be efficient when applied to common spatial data and establishes a methodology that will allow similar studies to be undertaken elsewhere

comparison of gis based gullying susceptibility mapping using bivariate and multivariate statistics northern calabria south italy abstract this paper presents gis aided procedures for the evaluation of gullying susceptibility on a statistical basis field surveys and air photo interpretation allowed us to identify gullies geology and land use while some predisposing factors were derived from a 7 5 m cell size dem in order to investigate the role of each instability factor in controlling the spatial distribution of gullies we implemented four models that differ in the types of method bivariate vs multivariate training set sampling polygon or point based and variables continuous or categorical the models were applied to the turbolo river catchment a tributary of the crati river northern calabria italy the susceptibility values were classified into five categories model performance was evaluated using prediction rate curves and by comparing the proportion of each susceptibility class with gully distribution in the validation set although all models showed relatively good performances the bivariate method overestimated the extent of the high susceptibility classes the multivariate logistic regression model using continuous variables was found to be the best model in predicting gullying susceptibility of the study area the area classified as stable increased with dem cell size meaning that a reasonably fine dem should be used

modelling the occurrence of gullies in rangelands of southwest spain gully erosion has been recognized as an important soil degradation process in rangelands of southwest spain in this paper a relatively new data mining technique called multivariate adaptive regression splines mars was applied to construct a model capable of predicting the location of gullies a large database was used to support the model composed of a target variable presence or absence of gullies and 36 independent variables related to topography lithology soils rainfall land use and vegetation cover the performance of the model was evaluated using the receiver operating characteristic roc curve for five external datasets the model had high predictive power with values for the area under the roc curve of the external validation datasets varying from 0 75 to 0 98 1 0 being perfect prediction the most important variables explaining the spatial distribution of gullies were lithology and soil type finally the model was compiled and implemented into a geographical information system to obtain maps of susceptible areas for gully erosion these maps show that approximately 7 of the study area presents favourable conditions for the development of gullies the results demonstrate that mars constitutes a valuable model in geomorphic research and could also be a useful tool for assessing the impacts of changing climate and land use on gully erosion copyright 2009 john wiley sons ltd

prediction of mining induced surface subsidence and ground movements at a canadian diamond mine using an elastoplastic finite element model a full three dimensional elastoplastic finite element model of diavik diamond mine is developed to predict surface induced ground movement due to underground blasthole stoping activities a mesh convergence study has been conducted to reach to an optimum meshing scenario when further mesh refinements produce a negligible change in the results this way the calculation cost and time has been managed successfully furthermore sequences of the excavation backfilling in the model are defined according to the mine production plan however some simplifications in the shape of the stopes have been made consequently the developed finite element model simulates the complete stress strain path through the entire excavation and backfilling simulation steps in full three dimensional space the model is calibrated using two extensometers installed on the back of two secondary undercut drifts in one of the kimberlite pipes the results of the calibrated model are validated using pit surface prism monitoring system data the average relative error between the measured data and fe model predictions is 7 95 it is shown that the numerical predictions of the mining induced surface subsidence due to the blasthole stoping mining method matched well with the gaussian distribution a significant increase approximately by 44 to the amount of the induced settlements on the surface occurred as the mining activities reaches near surface ground levels finally the comparison between the predicted results of the finite element model and monitoring data showed that the predictive capacity of the numerical model is a valuable tool for stability and design analysis of underground mines

a functional entity approach to predict soil erosion processes in a small plio pleistocene mediterranean catchment in northern chianti italy abstract in this paper we evaluate different methods to predict soil erosion processes we derived different layers of predictor variables for the study area in the northern chianti italy describing the soil lithologic complex land use and topographic characteristics for a subcatchment of the orme river we mapped erosion processes by interpreting aerial photographs and field observations these were classified as erosional response units eru i e spatial areas of homogeneous erosion processes the eru were used as the response variable in the soil erosion modelling process we applied two models i bootstrap aggregation random forest rf and ii stochastic gradient boosting treenet tn to predict the potential spatial distribution of erosion processes for the entire orme river catchment the models are statistically evaluated using training data and a set of performance parameters such as the area under the receiver operating characteristic curve auc cohen s kappa and pseudo r2 variable importance and response curves provide further insight into controlling factors of erosion both models provided good performance in terms of classification and calibration however tn outperformed rf similar classes such as active and inactive landslides can be discriminated and well interpreted by considering response curves and relative variable importance the spatial distribution of the predicted erosion susceptibilities generally follows topographic constraints and is similar for both models hence the model based delineation of eru on the basis of soil and terrain information is a valuable tool in geomorphology it provides insights into factors controlling erosion processes and may allow the extrapolation and prediction of erosion processes in unsurveyed areas

landslide susceptibility delineation in the ar rayth area jizan kingdom of saudi arabia using analytical hierarchy process frequency ratio and logistic regression models mountain areas in the southern western corner of the kingdom of saudi arabia ksa frequently suffer from various types of landsides induced by rainstorms and anthropogenic activities to mitigate these problems landslide susceptibility mapping and classification is important to develop quick and safe mitigation or remediation measures and to help the decision making in future planning by identifying the most vulnerable areas this paper summarizes the findings of a landslide susceptibility analysis in the ar rayth area jizan ksa using an analytical hierarchy process ahp frequency ratio fr and logistic regression lr models with the aid of gis tools and remote sensing data the landslide inventory map was prepared according to historical data interpretation of high resolution satellite images geo eye 0 5 m resolution and quickbird 0 6 m resolution topographic maps 1 10 000 and verified by field investigations an inventory map with 253 landslides locations was extracted from many sources the landslide inventory was randomly divided into two datasets 75 for training the models and 25 for validation an enhanced thematic mapper plus 15 m satellite image acquired in 2006 was used for determining the normalized difference vegetation index a contour map 1 10 000 with a 10 m contour interval was converted to digital elevation model 10 m resolution and subsequently converted to slope slope aspect curvature elevation and drainage networks geological data obtained with the help of satellite images were used to prepare lithological units and lineaments roads were digitized from the high resolution image and a rainfall map was prepared from the rainfall gauges distributed throughout the study area all these data were used to construct a spatial database using gis and image processing three landslide susceptibility maps were constructed one on the basis of a heuristic method using an ahp the other two on the basis of landslide inventories and causative factors using fr and lr furthermore each causative factor s weight was determined according to these three models and landslide susceptibility indices were calculated for verification receiver operating characteristic curves were calculated and the areas under the curve auc for success rate are 0 755 0 828 and 0 749 and for prediction rate are 0 708 0 781 and 0 727 for the ahp fr and lr respectively in addition the percentage of existing training landslides data in high and very high zones of the susceptibility maps is of 73 2 85 31 and 88 59 and for the validation landslides data is 73 2 85 31 and 88 59 for the ahp fr and lr respectively the findings indicated that the values of auc are above 0 7 for both success and prediction rate which indicate these three models are suitable for susceptibility analysis also percent of training and validation landslides data of high and very high zones indicate that lr model is more accurate followed by fr model and ahp model

radiocarbon chronology of lake bonneville eastern great basin usa abstract lake bonneville occupied a series of connected topographically closed structural basins in the eastern great basin from about 30 ka to 12 ka the following synthesis of lake bonneville history is based on a critical evaluation of the stratigraphic and geomorphic contexts of 83 radiocarbon ages of a variety of samples including wood charcoal dispersed organic matter mollusk shells and tufa the lake began to rise from levels close to average holocene levels after about 28 ka by 22 ka it had transgressed approximately 100 m between 22 and 20 ka it regressed about 45 m in the stansbury oscillation and the stansbury shoreline was formed transgression after 20 ka proceeded in two phases a rapid phase from 20 to 18 ka and a slower phase from 18 to 15 ka the lake overflowed intermittently at its highest level the bonneville shoreline from about 15 to 14 5 ka then catastrophically dropped 100 m during the bonneville flood to the level of the provo shoreline which it occupied until about 14 ka subsequent closed basin regression was rapid and complete by 12 ka and was followed by a modest transgression to form the gilbert shoreline between 10 9 and 10 3 ka the lake bonneville record is an accurate proxy of the changing water balance in the bonneville basin during the late pleistocene although the nature of the climatic changes during this period are still uncertain

estimating the quality of landslide susceptibility models we present a landslide susceptibility model for the collazzone area central italy and we propose a framework for evaluating the model reliability and prediction skill the landslide susceptibility model was obtained through discriminant analysis of 46 thematic environmental variables and using the presence of shallow landslides obtained from a multi temporal inventory map as the dependent variable for statistical analysis by comparing the number of correctly and incorrectly classified mapping units it is established that the model classifies 77 0 of 894 mapping units correctly model fitting performance is investigated by comparing the proportion of the study area in each probability class with the corresponding proportion of landslide area we then prepare an ensemble of 350 landslide susceptibility models using the same landslide and thematic information but different numbers of mapping units this ensemble is exploited to investigate the model reliability including the role of the thematic variables used to construct the model and the model sensitivity to changes in the input data by studying the variation of the model s susceptibility estimate the error associated with the susceptibility assessment for each mapping unit is determined this result is shown on a map that complements the landslide susceptibility map prediction skill of the susceptibility model is then estimated by comparing the forecast with two recent event inventory maps the susceptibility model is found capable of predicting the newly triggered landslides a general framework for testing a susceptibility model is proposed including a scheme for ranking the quality of the susceptibility assessment

arsenic in groundwater testing pollution mechanisms for sedimentary aquifers in bangladesh in the deltaic plain of the ganges meghna brahmaputra rivers arsenic concentrations in groundwater commonly exceed regulatory limits 50 m gl 21 because feooh is microbially reduced and releases its sorbed load of arsenic to groundwater neither pyrite oxidation nor competitive exchange with fertilizer phosphate contribute to arsenic pollution the most intense reduction and so severest pollution is driven by microbial degradation of buried deposits of peat concentrations of ammonium up to 23 mg l 21 come from microbial fermentation of buried peat and organic waste in latrines concentrations of phosphorus of up to 5 mg l 21 come from the release of sorbed phosphorus when feooh is reductively dissolved and from degradation of peat and organic waste from latrines calcium and barium in groundwater come from dissolution of detrital and possibly pedogenic carbonate while magnesium is supplied by both carbonate dissolution and weathering of mica the 87 sr 86 sr values of dissolved strontium define a two component mixing trend between monsoonal rainfall 0 711 6 0 001 and detrital carbonate 0 735

mineralogy and geochemistry affecting arsenic solubility in sediment profiles from the shallow basin fill aquifer of cache valley basin utah abstract elevated arsenic concentrations have been reported in groundwater samples collected from the semi arid western u s including the cache valley basin utah the volcanic rock in the basin fill aquifers underlying portions of the west is considered the primary source of arsenic but there is debate about the mechanisms that control arsenic solubilization in these semi arid and arid climates sediment cores were collected from a shallow basin fill aquifer in the cache valley basin to systematically determine arsenic mineralogy and solubilization mechanisms in relation to non redox and redox induced soil processes soluble arsenic was present throughout the two studied profiles in varying abundance and oxidation state with the highest concentration of soluble as v and as iii at the depth of the water table sequential chemical extractions of arsenic with oxidation preservation strategies revealed mineral sources and sinks of arsenic vulnerable to altering redox conditions down the profile weathering of primary arsenic bearing minerals resulted in soluble arsenic in the vadose zone once soluble arsenic was leached to the deeper profile arsenic solubility was controlled by carbonate minerals that concentrate at the water table in the zone with alternating oxidizing and reducing conditions iron oxides became the controlling mineral phase the association between arsenic and sulfides limited arsenic solubility at depths under permanent water saturation arsenic solubility was revealed to be controlled by a sequence of processes that prevail under different geochemical regimes down the profile

mineralogy and geochemistry of shallow sediments of sonargaon bangladesh and implications for arsenic dynamics focusing on the role of organic matter abstract mineralogy and geochemistry of modern shallow sediments up to 5 m thick within the zone of water table fluctuations were studied to determine the likely sources and processes responsible for releasing as into groundwater samples were collected from different geological settings with varying groundwater as concentrations during dry december 2005 and wet september 2006 seasons at sonargaon bangladesh stratigraphic sequences of the studied sediments showed three distinct lithofacies viz clayey silt silty clay and silty very fine sand corresponding to fine grained overbank associations total as concentrations of shallow sediments ranged from 80 of the as was fixed in insoluble and organic phases while the amount of as in reducible and acid soluble phases was very low

mobility of arsenic in a bangladesh aquifer inferences from geochemical profiles leaching data and mineralogical characterization aquifer geochemistry was characterized at a field site in the munshiganj district of bangladesh where the groundwater is severely contaminated by as vertical profiles of aqueous and solid phase parameters were measured in a sandy deep aquifer depth 150 m below a thick confining clay 119 to 150 m a sandy upper aquifer 3 5 to 119 m above this confining layer and a surficial clay layer 3 5 m in the deep aquifer and near the top of the upper aquifer aqueous as levels are low 10 g l but aqueous as approaches a maximum of 640 g l at a depth of 30 to 40 m and falls to 58 g l near the base 107 m of the upper aquifer in contrast solid phase as concentrations are uniformly low rarely exceeding 2 g g in the two sandy aquifers and never exceeding 10 g g in the clay layers solid phase as is also similarly distributed among a variety of reservoirs in the deep and upper aquifer including adsorbed as as coprecipitated in solids leachable by mild acids and reductants and as incorporated in silicates and other more recalcitrant phases one notable difference among depths is that sorbed as loads considered with respect to solid phase fe extractable with 1 n hcl 0 2 m oxalic acid and a 0 5 m ti iii citrate edta solution appear to be at capacity at depths where aqueous as is highest this suggests that sorption limitations may in part explain the aqueous as depth profile at this site competition for sorption sites by silicate phosphate and carbonate oxyanions appear to sustain elevated aqueous as levels in the upper aquifer furthermore geochemical profiles are consistent with the hypothesis that past or ongoing reductive dissolution of fe iii oxyhydroxides acts synergistically with competitive sorption to maintain elevated dissolved as levels in the upper aquifer microprobe data indicate substantial spatial comapping between as and fe in both the upper and deep aquifer sediments and microscopic observations reveal ubiquitous fe coatings on most solid phases including quartz feldspars and aluminosilicates extraction results and xrd analysis of density magnetic separates suggest that these coatings may comprise predominantly fe ii and mixed valence fe solids although the presence of fe iii oxyhydroxides can not be ruled out these data suggest as release may continue to be linked to dissolution processes targeting fe or fe rich phases in these aquifers copyright 2004 elsevier ltd

gully erosion susceptibility assessment by means of gis based logistic regression a case of sicily italy article i nfo article history this research aims at characterizing susceptibility conditions to gully erosion by means of gis and multivariate statistical analysis the study area is a 9 5 km 2 river catchment in central northern sicily where agriculture ac tivities are limited by intense erosion by means of field surveys and interpretation of aerial images we prepared a digitalmap of thespatial distribution of 260 gulliesinthestudy area inaddition fromavailable thematicmaps a 5 m cell size digital elevation model and field checks we derived 27 environmental attributes that describe the variability of lithology land use topography and road position these attributes were selected for their potential influence on erosion processes while the dependent variable was given by presence or absence of gullies within two different types of mapping units 5 m grid cells and slope units average size 2 66 ha the functional re lationships between gully occurrence and the controlling factors were obtained from forward stepwise logistic regression to calculate the probability to host a gully for each mapping unit in order to train and test the predictive models three calibration and three validation subsets of both grid cells and slope units were randomly selected results of validation based on roc receiving operating characteristic curves attest for acceptable to excellent accuracies of the models showing better predictive skill and more stable performance of the susceptibility model based on grid cells

a methodology based on strain analysis for identifying potential discontinuous deformation zones in sublevel caving mines abstract underground mining operations using the sublevel caving method often result in discontinuous ground deformations involving surface cracks determining the limit of the discontinuous deformation zone is important for the relocation of neighbouring residential areas mining infrastructure and the planning of underground mining operations the limit of the discontinuous deformation zone is characterised by the outermost surface crack which is a tensile crack when it occurs and is correlated with the horizontal ground tensile strain in this study a mathematical procedure combining the horizontal displacement as periodically monitored by total station and gps multiquadric radial basis function mq rbf interpolation and continuum mechanics is provided to calculate the strain state at any point on the ground then the relationship between a new tensile crack and horizontal ground tensile strain is studied to determine the criterion representing the presence of a new tensile crack this means that when the criterion at any point on the ground is satisfied the point will have the potential to crack based on this the potential discontinuous deformation zone where surface cracks may occur can be identified potential break angles at representative sections can then be determined a case study is presented to illustrate the results given by the above methodology the result shows that when major principal horizontal ground strain e1 at any point on the ground reaches the potential cracking major principal strain pcmps 6 mm m in this case study the point will have the potential to crack subsequently the area within the outermost contour of the pcmps can be defined as the potential discontinuous deformation zone moreover the approximate matching of the limits of potential discontinuous deformation zones and surface cracks verifies the reliability of the mathematical procedure and the rationality of the pcmps in identifying the discontinuous deformation zone additionally in this case study the potential break angles at two respective sections are significantly different indicating that the break angles should be further studied and care taken in design of works in these two zones respectively

arsenic solubilization and redistribution under anoxic conditions in three aquifer sediments from a basin fill aquifer in northern utah the role of natural organic carbon and carbonate minerals abstract the basin fill aquifers of the western u s contain elevated concentrations of arsenic in the groundwater due to ancient volcanic deposits that host arsenic minerals microcosms were constructed using two oxidized sediments and by contrast a reduced sediment collected from a shallow basin fill aquifer in the cache valley basin northern utah to evaluate the fate of geologic arsenic under anoxic conditions sequential extractions indicated the primary arsenic host mineral was amorphous iron oxides but 13 17 of the total arsenic was associated with carbonate minerals arsenic was solubilized from the sediments when incubated with groundwater in the presence of native organic carbon arsenic solubilization occurred prior to iron reduction rather than the commonly observed co reactivity arsenic v associated with carbonate minerals was the main source of arsenic released to solution and redistributed onto less soluble minerals including fes and siderite as defined by chemical extraction arsenic reduction occurred only in the site oxidized sediments the addition of a carbon and energy source glucose resulted in enhanced arsenic solubilization which was coupled with iron reduction from the site oxidized sediments adding glucose promoted iron reduction that masked the role of carbonate minerals in arsenic solubilization and retention as observed with incubation with groundwater only

geochemistry and arsenic behaviour in groundwater resources of the pannonian basin hungary and romania abstract groundwater resources in the pannonian basin hungary romania croatia and serbia are known to contain elevated naturally occurring as published estimates suggest nearly 500 000 people are exposed to levels greater than the eu maximum admissible concentration of 10 g l in their drinking water making it the largest area so affected in europe in this study a variety of groundwaters were collected from romania and hungary to elucidate the general geochemistry and identify processes controlling as behaviour concentrations ranged from so 4 2 reduction containing low as levels so 4 2 ongoing so 4 2 reduction will release s2 removing as from solution either by the formation of as sulfides or from sorption onto fe sulfide phases in methanogenic waters as released by reductive dissolution is not removed from solution and can rise to the high levels observed levels of organic c are thought to be the ultimate control on the redox conditions in these 2 groups high levels of organic c as found in group 1 would quickly exhaust any so 4 2 present in the waters driving the system to methanogenesis and subsequent high levels of as group 2 has much lower concentrations of organic c and so so 4 2 is not exhausted therefore as levels in waters of the pannonian basin are controlled not by release but by retention mechanisms ultimately controlled by levels of toc and so 4 2 in the waters d and 18o analysis showed that groundwaters containing elevated as dated mostly from the last ice age and are sourced from late pliocene to quaternary aquifers the importance of toc and retention capabilities of so 4 2 reduction have only previously been suggested for recent holocene sediments and groundwater most notably those in se asia as these are the most likely to contain the right combination of factors to drive the system to a redox situation leading to high aqueous as concentrations in contrast it is shown here that a much older system containing as bearing fe oxides also has the potential to produce elevated levels of as if the toc is suitable for the microbial population to drive the system to the correct redox situation and so 4 2 is either absent or wholly consumed