predictive modeling of slope deposits and comparisons of two small areas in northern germany abstract methods for correct quantitative comparison of several terrains are important in the development and use of quantitative landscape evolution models and they need to introduce specific modeling parameters we introduce such parameters and compare two small terrains with respect to the link slope valley for the description of slope deposits colluvium in them we show that colluvium accumulation in small areas cannot be described by linear models and thus introduce non linear models two small areas perdoel 0 29 ha and bornhoved 3 2 ha are studied slope deposits in the both are mainly in dry valleys with a total thickness m total up to 2 0 m in perdoel and up to 1 2 m in bornhoved parent materials are mainly pleistocene sands aged 30 kyr bp exponential models of multiple regression that use a 1 m lidar dem digital elevation model explained 70 93 of spatial variability in m total parameters dh 12 and dv 12 of horizontal and vertical distances are introduced that permit to characterize and compare conditions of colluvium formation for various terrains the study areas differ 3 7 times by the parameter dh 12 that describes a horizontal distance from thalwegs at which m total diminishes 2 72 times dh 12 is greater in bornhoved 29 7 m than in perdoel 8 12 m we relate this difference in dh 12 to the distinction between types of the link slope valley a regional type if catchment area of a region outside a given small area plays an important role and a local type when accumulation of colluvium from valley banks within a small area is of more importance we argue that the link slope valley is regional in perdoel and local in bornhoved peaks of colluvium thickness were found on thalwegs of three studied valleys by both direct measurements in a trench and model surfaces of m total a hypothesis on the formation mechanism of such peaks is discussed the parameter dv 12 describes a vertical distance from a peak of colluvium thickness along valley bottom at which m total diminishes 2 72 times values of this parameter differ 1 4 times for the study areas dv 12 is greater in perdoel 3 0 m than in bornhoved 2 1 m thus indicating more sharp peaks of m total in bornhoved exponential models allow construction of predictive maps of buried pleistocene surfaces for both the terrains and calculate colluvium volumes with an error 4 2 for perdoel and 7 1 for bornhoved comparisons of buried and present surfaces showed that the latter are more smoothed more strongly in valleys where flow branching is increased

using multiple logistic regression and gis technology to predict landslide hazard in northeast kansas usa abstract landslides in the hilly terrain along the kansas and missouri rivers in northeastern kansas have caused millions of dollars in property damage during the last decade to address this problem a statistical method called multiple logistic regression has been used to create a landslide hazard map for atchison kansas and surrounding areas data included digitized geology slopes and landslides manipulated using arcview gis logistic regression relates predictor variables to the occurrence or nonoccurrence of landslides within geographic cells and uses the relationship to produce a map showing the probability of future landslides given local slopes and geologic units results indicated that slope is the most important variable for estimating landslide hazard in the study area geologic units consisting mostly of shale siltstone and sandstone were most susceptible to landslides soil type and aspect ratio were considered but excluded from the final analysis because these variables did not significantly add to the predictive power of the logistic regression soil types were highly correlated with the geologic units and no significant relationships existed between landslides and slope aspect

the role of biological agents in the microstructural and mineralogical transformations in aluminium lateritic deposit in central brazil abstract petrological studies using x ray diffraction xrd and micromorphological analyses optical microscopy and sem were done to understand the role of biological activity in the evolution of barro alto bauxite the results indicated that this influence came through structural or microstructural and mineralogical transformations namely i the bioturbation caused by termites and ii the mechanical degradation and geochemical transformation promoted by roots in the bioturbation caused by termites were formed i a intergrain micro aggregate structure characterised by gibbsite crystals from isalteritic bauxite fragmentation on the bottom of the profile and ii a granular structure characterised by a termitic microaggregates with fragments of gibbsite immersed in a kaolinite gibbsite goethite boehmite micromass formed by bioturbation of the degradation clay with nodules of gibbsite whose origin is the geochemistry degradation of isalteritic bauxite the processes associated with geochemical and mechanical degradation caused by roots were responsible for the genesis of i a porphyric texture with bauxite fragments surrounded by nonaggregate material and ii fine monic structure where the gibbsite neoformation has the mould cavities left by old roots generating riziform features

scale matters a multi resolution study of the determinants of patterned ground activity in subarctic finland abstract numerical studies of earth surface processes in relation to their environment are one of the central topics in physical geography however collinearity between explanatory variables and spatial autocorrelation can hinder the detection of key environmental correlates underlying response explanatory variables relationships identified by traditional regression methods moreover conclusions about the potential importance of environmental variables have generally made on analysis conducted only at one spatial scale resolution in this study a variation partitioning method provided a framework to obtain new insights into the relative roles of different factors determining patterned ground activity at multiple spatial resolutions the variation in the distribution of the sorted and non sorted patterned ground was decomposed into independent and joint effects of relief soil and spatial variables geographical location based on a multi resolution system of 1 ha 25 ha and 100 ha cells covering in total 100 km 2 of a subarctic landscape in northern finland the independent effects of relief and soil variables captured the largest fraction of the variation in the non sorted patterned ground distribution while relief had a major contribution for sorted patterned ground activity the independent effect of spatial autocorrelation on sorted patterned ground was higher than that on non sorted patterned ground however a considerable amount of variation in the distribution of both patterned ground types was accounted for by the joint effects of explanatory variables and may thus be causally related to two or all three groups of variables our analyses produced often contradicting results at different resolutions consequently this has substantial implications for the study of geomorphological systems since the choice of resolution can have a major effect on the inferences of analyses our results draw attention to the roles of resolution and spatial autocorrelation in the study of geomorphological systems

transferability of regional permafrost disturbance susceptibility modelling using generalized linear and generalized additive models abstract to effectively assess and mitigate risk of permafrost disturbance disturbance prone areas can be predicted through the application of susceptibility models in this study we developed regional susceptibility models for permafrost disturbances using a field disturbance inventory to test the transferability of the model to a broader region in the canadian high arctic resulting maps of susceptibility were then used to explore the effect of terrain variables on the occurrence of disturbances within this region to account for a large range of landscape characteristics the model was calibrated using two locations sabine peninsula melville island nu and fosheim peninsula ellesmere island nu spatial patterns of disturbance were predicted with a generalized linear model glm and generalized additive model gam each calibrated using disturbed and randomized undisturbed locations from both locations and gis derived terrain predictor variables including slope potential incoming solar radiation wetness index topographic position index elevation and distance to water each model was validated for the sabine and fosheim peninsulas using independent data sets while the transferability of the model to an independent site was assessed at cape bounty melville island nu the regional glm and gam validated well for both calibration sites sabine and fosheim with the area under the receiver operating curves auroc 0 79 both models were applied directly to cape bounty without calibration and validated equally with auroc s of 0 76 however each model predicted disturbed and undisturbed samples differently additionally the sensitivity of the transferred model was assessed using data sets with different sample sizes results indicated that models based on larger sample sizes transferred more consistently and captured the variability within the terrain attributes in the respective study areas terrain attributes associated with the initiation of disturbances were similar regardless of the location disturbances commonly occurred on slopes between 4 and 15 below holocene marine limit and in areas with low potential incoming solar radiation

gis techniques and statistical models in evaluating landslide hazard geographical information systems gis and numerical cartography may greatly facilitate the development and use of statistical models for the assessment of regional landslide hazard from a small drainage basin located in central italy relevant geological and geomorphological factors were collected and processed by applying gis technology in particular modules were used which both generate high fidelity digital terrain models and automatically partition the terrain into main slope units the resulting information was then analysed by discriminant analysis which enabled landslide hazard and risk to be evaluated in each slope unit although not lacking drawbacks the method proved to be a feasible and cost effective approach to landslide susceptibility assessment and mapping

buried in ashes site formation processes at lapa do santo rockshelter east central brazil few archaeological sites in the americas contain high concentrations of human burials dating back to the early holocene the tropical karstic region of lagoa santa in central brazil state of minas gerais is one of the richest bioanthropological records available to study the behaviors and funerary practices of early holocene south americans with more than 200 skeletons found so far one of the key locations to examine the history of human settlement in lagoa santa is the site of lapa do santo a rockshelter known to contain the oldest rock art and the earliest evidence of funerary complexity in the continent in this geoarchaeological investigation we focus on the early holocene settlement at lapa do santo 7 9 12 7 cal kybp applying high resolution geoarchaeological techniques such as micromorphology organic petrology and ftir on both archaeological modern reference and experimental samples this is the first time that a micro contextual approach integrated with experimental geoarchaeology has been applied to study the formation of rockshelter deposits in a tropical setting our results show that the stratigraphic sequence formed under the dual influence of anthropogenic sedimentation through continuous combustion activities and geogenic sedimentation in the form of oxisol aggregates which fell from above the limestone cliff into the rockshelter intact hearths and remobilized combustion debris possibly hearth rake out are close to the graves suggesting repeated burning activities as part of the ritual behavior of early holocene south americans large amounts of ash are intermixed with heated and unheated oxisol aggregates heated termite mound fragments were also found mixed within the sediments post depositional alteration of the site includes limited bioturbation and localized low energy surface water and sub surface concentrations of moisture leading to precipitation of dense secondary carbonates the age inversions can be attributed to the human action of reworking the ashy sediments and not to post abandonment processes despite this the overall preservation of the sediments is good and most human burials can be considered to be in primary context

artificial neural networks applied to landslide susceptibility assessment abstract landslide hazard mapping is often performed through the identification and analysis of hillslope instability factors usually managed as thematic data within geographic information systems gis in heuristic approaches these factors are rated by the attribution of scores based on the assumed role played by each of them in controlling the development of a sliding process other more refined methods based on the principle that the present and the past are keys to the future have also been developed thus allowing less subjective analyses in which landslide susceptibility is assessed by statistical relationships between past landslide events and hillslope instability factors the objective of this research is to define a method with the ability to forecast landslide susceptibility through the application of artificial neural networks anns the riomaggiore catchment a subwatershed of the reno river basin located in the northern apennines italy was chosen as an ideal test site as it is representative of many of the geomorphological settings within this region in the present application two different anns used in classification problems were set up and applied one belonging to the category of multi layered perceptron mlp and the other to the probabilistic neural network pnn family the hillslope factors that have been taken into account in the analysis were the following a lithology b slope angle c profile curvature d land cover and e upslope contributing area these factors have been classified on nominal scales and their intersection allowed 3342 homogeneous domains unique condition unit ucu to be singled out which correspond to the terrain units utilized in this analysis the model vector used to train the anns is a subset of that derived from the production of unique condition units and consists of 3342 records organized in input and output variable vectors in particular the hillslope factors once classified on nominal scales as binary numbers represent the 19 input variables while the presence absence of a landslide in a given terrain unit is assumed to be the output variable the comparison between the most up to date landslide inventory of the riomaggiore catchment and the hazardous areas as predicted by the anns showed satisfactory results with a slight preference for the mlp for this reason this is an encouraging preliminary approach towards a systematic introduction of ann based statistical methods in landslide hazard assessment and mapping

digital terrain modelling a review of hydrological geomorphological and biological applications the topography of a catchment has a major impact on the hydrological geomorphological and biological processes active in the landscape the spatial distribution of topographic attributes can often be used as an indirect measure of the spatial variability of these processes and allows them to be mapped using relatively simple techniques many geographic information systems are being developed that store topographic information as the primary data for analysing water resource and biological problems furthermore topography can be used to develop more physically realistic structures for hydrologic and water quality models that directly account for the impact of topography on the hydrology digital elevation models are the primary data used in the analysis of catchment topography we describe elevation data sources digital elevation model structures and the analysis of digital elevation data for hydrological geomorphological and biological applications some hydrologic models that make use of digital representations of topography are also considered

a micromorphological view through a namaqualand termitaria heuweltjie a mima like mound heuweltjies occur throughout namaqualand and the western and southern cape coasts broad low relief termitaria of the harvester termite microhodotermes viator which show different vegetation patterns to the surrounding soils distinguishable even in satellite images there is a direct relationship between soil hardpan occurrence and the heuweltjies characteristically in the semi arid areas the hardpans grade outwards from a central sepiolitic petrocalcic horizon laterally through petro sepiolitic palygorskitic variable in the degree of cementation to the petroduric horizon on the edges in a landscape in which these hardpans are otherwise absent the aim of the study was to investigate the genesis of these hardpans associated with the heuweltjie mound with a particular focus on the build up of calcite and sepiolite the micromorphological study examined a transect through a representative sepiolite bearing heuweltjie on the coast near the olifants river mouth and revealed evidence of termite activity in the central petro calcic part of the mound this concentration of calcite and mg rich clay in the centre can be explained by termite foraging as the regionally characteristic ca and mg rich foliage is moved into the centre of the mound facilitating the precipitation of calcite and sepiolite as bacterial decomposition and subsequent leaching modify the soil solution in the mound the increase in coarse fine ratio from the centre outward showed that accumulation of calcite and sepiolite displaced the original sand matrix by a greater degree than the silica accumulation consistent with the topographically raised surface in the centre limpid yellow low birefringent nodules some with pseudo negative uniaxial interference figures showed a fibrous nature under esem and their low ca and molar mg si ratios of 0 64 to 0 68 esem edx were consistent with sepiolite the presence of the sepiolite with its mg rich composition and hydrophilic character together with organic acids generated from the vegetation collected by the termites is considered to be an explanation for the formation of ooids radial calcite crystals associated with a core of sepiolite colourless non calcareous pseudo uniaxial negative spherulites were present in fresh termite excrement from an active heuweltjie near stellenbosch these were either produced in the termite gut itself or had been ingested along with herbivore dung by the termites the presence of faecal spherulites in termite excrement is significant since it shows that faecal spherulites can be distributed over a wider area than that directly associated with mammalian herbivores

behaviour of new zealand glaciers and atmospheric circulation changes over the past 130 years there is renewed interest as to the impact of future climate change on temperate alpine glaciers because of their role as indicators of past and ongoing changes and due to their possible involvement in sea level rise substantial changes in termini of new zealand glaciers since the nineteenth century are compared with variations in atmospheric circulation patterns over the southwest pacific region reconstructed sea level pressure patterns are used back to 1911 atmospheric circulation indices obtained from pressure differences between appropriate stations are extended back to the 1860s circulation anomalies are examined for winter related to glacier accumulation and for summer related to glacier ablation behaviour of glacier termini is found to be strongly linked with circulation changes especially in summer latitudinal shifts in the southern margin of the subtropical high pressure zone are identified as important an advance of some glaciers since 1980 is consistent with circulation changes over the new zealand region induced by two large el nino events

long term evolution of denudational escarpments in southeastern brazil article i nfo topographic relief in southeastern brazil consists of a sequence of stepped surfaces that formed after the frag mentation of gondwana during the cretaceous tertiary and quaternary tectonic pulses this region is drained by four major rivers within four major river basins with interfluves that contain denudational escarpments fault escarpments and mountain ranges this study presents an analysis of the long term evolution of two denudational escarpments the cristiano otoni and the sao geraldo steps which divide the river basins of the sao francisco doce and paraiba do sul rivers in southeastern brazil denudation rates were obtained through the measurement of mean concentrations of in situ produced cosmogenic 10

can geodiversity be predicted from space abstract identification of geodiversity at regional and national scales with traditional surveying techniques remains a logistically difficult and often financially prohibitive task earth observation data in combination with statistical modeling may provide a unique approach for mapping and analyzing geodiversity cost efficiently in this study the possibility to map geodiversity using digital elevation models dems and remote sensing rs data was scrutinized in finland northern europe at a landscape scale the main methods in the evaluation of spatial prediction ability of geodiversity and the relative contributions of dem and rs data were generalized additive modeling gam and variation partitioning based on the results geodiversity was mainly determined by polygenetic bedrock topography and fluvial activity and correlated most strongly with variables describing high potential energy and topographical heterogeneity the spatial patterns of geodiversity were robustly predicted across the study areas using multivariate gams the higher predictive performance of the dem versus rs based variables was evident across the study areas in conclusion we propose that statistically based spatial prediction offers an opportunity for characterizing geodiversity of a large area in a systematic repeatable and spatially exhaustive manner

landslide hazard evaluation a review of current techniques and their application in a multi scale study central italy in recent years growing population and expansion of settlements and life lines over hazardous areas have largely increased the impact of natural disasters both in industrialized and developing countries third world countries have difficulty meeting the high costs of controlling natural hazards through major engineering works and rational land use planning industrialized societies are increasingly reluctant to invest money in structural measures that can reduce natural risks hence the new issue is to implement warning systems and land utilization regulations aimed at minimizing the loss of lives and property without investing in long term costly projects of ground stabilization government and research institutions worldwide have long attempted to assess landslide hazard and risks and to portray its spatial distribution in maps several different methods for assessing landslide hazard were proposed or implemented the reliability of these maps and the criteria behind these hazard evaluations are ill formalized or poorly documented geomorphological information remains largely descriptive and subjective it is hence somewhat unsuitable to engineers policy makers or developers when planning land resources and mitigating the effects of geological hazards in the umbria and marche regions of central italy attempts at testing the proficiency and limitations of multivariate statistical techniques and of different methodologies for dividing the territory into suitable areas for landslide hazard assessment have been completed or are in progress at various scales these experiments showed that despite the operational and conceptual limitations landslide hazard assessment may indeed constitute a suitable cost effective aid to land use planning within this framework engineering geomorphology may play a renewed role in assessing areas at high landslide hazard and helping mitigate the associated risk

improving sinkhole hazard models incorporating magnitude frequency relationships and nearest neighbor analysis abstract this work presents a methodology for elaborating sinkhole hazard models that incorporate the magnitude and frequency relationships of the subsidence process the proposed approach has been tested in a sector of the ebro valley mantled evaporite karst where sinkholes largely induced by irrigation practices have a very high occurrence rate 50 sinkholes km 2 yr in this area covering 10 km 2 a total of 943 new cover collapse sinkholes were inventoried in 2005 and 2006 multiple susceptibility models have been generated analyzing the statistical relationships between the 2005 sinkholes and different sets of variables including the nearest sinkhole distance the quantitative evaluation of the prediction capability of these models using the 2006 sinkhole population has allowed the identification of the method and variables that produce the most reliable predictions the incorporation of the indirect variable nearest sinkhole distance has contributed significantly to increase the quality of the models despite simplifying the modeling process by using categorical rather than continuous variables the best susceptibility model generated with the total sinkhole population and the selected method and variables has been transformed into a hazard model that provides minimum estimates of the spatial temporal probability of each pixel to be affected by sinkholes of different diameter ranges this transformation has been carried out combining two equations derived from the more complete 2006 sinkhole population one of them expressing the expected spatial temporal probability of sinkhole occurrence and the other the empirical magnitude and frequency relationships generated for two different types of land surfaces which control the strength of the surface layer and the size of the sinkholes the presented method could be applied to predict the spatial temporal probability of events with different magnitudes related to other geomorphic processes e g landslides

ants as a powerful biotic agent of olivine and plagioclase dissolution the biotic enhancement of ca mg silicate weathering has helped maintain earth s habit ability over geological time scales by assisting in the gradual drawdown of atmospheric co 2 25 years of in situ measurements of ca mg silicate mineral dissolution by ants termites root mats bare ground and a control reveals ants to be one of the most powerful biotic weathering agents yet recognized six sites in arizona and texas usa indicate that eight different ant species enhance mineral dissolution by 50 300 over controls a comparison of extracted soil at a 50 cm depth in ant colonies and adjacent bare ground shows a gradual accumulation of caco 3 content for all eight ant species over 25 yr ants thus have potential to provide clues on how to enhance contemporary carbon sequestration efforts to transform ca mg sili cates and co 2 into carbonate given that ants underwent a great diversification and biomass expansion over the cenozoic a speculative implication of this research is that ant enhance ment of ca mg silicate dissolution might have been an influence on cenozoic cooling

pedogenesis in a pleistocene fluvial system of the northern pantanal brazil sedimentology and hydrology seem to play a predominant role in soil formation in the pantanal since the fluvial systems of this wetland provided quaternary sediments and shaped the landscape however pedogenic processes are active in this region mainly due to the floods that occur during the summer and fall season the goal of this work was to study the pedogenesis in a representative transect on the sao lourenco fluvial fan which has an area of about 16 000 km2 and is one of the largest sedimentary compartments of the northern pantanal west central brazil a transect of 125 m was studied in the late pleistocene sedimentary lobe of the fluvial fan where four landform elements were identified paleo channel paleo levee paleo floodplain and mound and described to show the soil horizon boundaries along the landform unit samples were collected from trenches auger holes and boreholes and were analyzed for soil description and characterization soil analyses carried out were macro and micromorphological physical chemical mineralogical c isotope fractionation and osl dating analyses the set of evidence shows that the studied transect originated from pleistocene sediments due to the activity of the sao lourenco fluvial fan the following soil landform element relationships developed quartzipsamments in the paleo channel plinthaquults in the paleo levee and paleo floodplain and natrustalfs in the mound evidences of pedogenic processes in the transect are a clay eluviation and illuviation resulting in formation of the bt horizon in the soils at the lower part of the transect and mound b gleization and plinthization mainly at the lower part of the transect resulting in formation of mottles reduced soil matrix and nodules plinthite and petroplinthite c bioturbation responsible for addition of materials at the soil surface assisting in the formation maintenance of the mound and d the sodium concentration observed in soils that have higher clay contents which are highest in the mound has the highest levels

effects of sample size on the accuracy of geomorphological models abstract commonly the most costly part of geomorphological distribution modelling studies is gathering the data thus guidance for researchers concerning the quantity of field data needed would be extremely practical this paper scrutinises the relationship between the sample size the number of observations varied from 20 to 600 and the predictive ability of the generalized linear model glm generalized additive model gam generalized boosting method gbm and artificial neural network ann in two data settings i e independent and split sample approaches the study was performed using empirical data of periglacial processes from an area of 600 km2 in northernmost finland at grid resolutions of 1 ha 100 100 m and 25 ha 500 500 m a rather sharp increase in the predictive ability of the models was observed when the number of observations increased from 20 to 100 and the level of robust predictions was reached with 200 observations the result indicates that no more than a few hundred observations are needed in geomorphological distribution modelling at a medium scale resolution ca 0 01 1 km2

interaction of geomorphic and ecologic features across altitudinal zones in a subarctic landscape abstract vegetation is often considered to stabilize geomorphic processes an increasing abundance of vegetation may cause negative feedbacks within a periglacial system in this study we explored the importance of vegetation on the occurrence of active cryoturbation dominated feature fields in subarctic finland on a landscape scale the vegetation cryoturbation interaction was studied across three altitudinal zones by applying hierarchical partitioning hp and variation partitioning vp methods that overcome collinearity problems in multivariate analysis firstly our results showed that vegetation factors especially the canopy cover of the field layer vegetation and the total above ground biomass were among the most important environmental variables affecting the occurrence of active cryoturbation features moreover vegetation factors were for the most part positively associated with cryoturbation under the predicted global warming the greening of arctic and subarctic regions may therefore decrease and also increase the activity of the periglacial processes in sparsely vegetated terrain secondly our analyses gave contrasting results of the environmental factors of the periglacial processes across altitudinal zones although the relative importance of the vegetation group was rather constant throughout the zones thus we stress the importance of the spatial study setting in geomorphic studies in topographically varying relief we recommend either taking the altitudinal zonation of the landscape into consideration or studying the features within a predetermined zone to decrease misinterpretations in environment process relationships methodologically our results encourage wider applications of partitioning methods in multivariate settings in geomorphology

rare earth and trace element geochemistry of termite mounds in central and northeastern namibia mechanisms for micro nutrient accumulation abstract rare earth element ree and trace element concentrations of ten termite mounds and adjacent topsoil from central and northeastern namibia were used to investigate the processes underlying the alteration of soil chemical and physical properties by termites macrotermes spp accumulation of micro nutrients in the mounds was of particular interest because of the ecological implications of the enhanced availability of these scarce elements the absolute concentrations of ree and trace elements including nine micro nutrients b fe mn ni cu zn se mo and cd were greater in termite mounds compared to topsoil suggesting a possible external supply of enriched materials or accumulation of in situ weathering products of the underlying bedrock similarities between the chondrite normalized ree patterns of the samples and those of the average upper continental crust ucc and post archaean average australian shale compositions indicated that the mounds and topsoil at each site originated from the same host bedrock coherent behavior between two incompatible elements th and la in both topsoil and mound samples suggested that the two sets of samples were exposed to two different weathering processes the relatively low zr sc ratios fine particle sizes and the persistence of positive eu anomalies of the mounds relative to ucc were interpreted as reflecting 1 a lack of grain sorting effects and 2 active transport of materials rich in primary clay minerals and trace elements from the deeper regolith to the surface by termites lower permeability of mound materials may also prevent leaching of primary minerals and trace elements titanium and zr enrichment in most mound samples 8 samples was attributed to the decomposition of biotite by macrotermes with the concomitant release of ti and zr into the mounds suggesting the termites ability to transform soil minerals and enhance chemical weathering this was further corroborated by a substantial increase in th u ratios in most mounds relative to topsoil because of the oxidizing conditions of the mounds ti and zr are likely to be adsorbed onto fe oxides positive ce anomalies relative to ucc and the high ph values in the mounds indicate calcrete aggradation or mound aeration as a result of burrowing activities of the termites and evaporation from mounds the impacts of the changes in environmental conditions and the termite activities on the mound geochemistry are highlighted by heavy ree hree as well as fe and mn retentions in the mounds heavy ree and light ree lree are likely to coprecipitate with carbonate complexes and fe and mn oxyhydroxides and in the process scavenge a series of micro nutrients such as zn cu cd and co a substantial enrichment of se in mounds despite the oxidizing conditions of the mounds could be attributed to active transport of se enriched materials from deep soil horizons the study demonstrated the suitability of ree and trace element geochemistry for assessing the influence of macrotermes on the physico chemical properties of semi arid soils

stratigraphy age and formation of peaty earth hummocks pounus finnish lapland detailed investigations of peaty earth hummocks called pounus were carried out in northemmost finnish lapland in the vicinity of the kevo subarctic research station pounus are complex often vegetated cryogenic mounds formed partly of peat some have a core of mineral soil or several large stones or just one frost heaved boulder covered by peat they belong to the same group of earth hummocks as thufur and non sorted circles the typology of pounus is described and compared with other types of cryogenic earth hummocks stratigraphical study of pounus shows how cryoturbation has deformed the previous soil horizons of typical arctic podzols and has been followed by intense peat growth and later frost reactivation microstructures in pounus confirm the frost activity and several phases of peat growth during their formation alternating warmer and dryer conditions with water table rise and renewed peat formation could be inferred the present stage of development is frost reactivation and peat growth poun

transferability of geomorphological distribution models evaluation using solifluction features in subarctic and arctic regions extrapolation potential of statistically based geomorphological distribution models gdms has not been scrutinized here the possibility to transfer solifluction models within and between six study areas in subarctic and arctic environments was examined a generalized linear model generalized additive model maximum entropy and boosted regression tree methods were used in the analyses the transferability success of the gdms was assessed by the area under the curve of a receiver operating characteristic plot based on the results slope angle mean annual air temperature and a remote sensing based index of vegetation abundance were the most important variables contributing to the occurrence of solifluction at a landscape scale in model extrapolation over half of the calibrated solifluction models were transferable from one area to another the topographical conditions of the study areas had a greater effect than climate conditions on the extrapolation potential more precisely it was more difficult to extrapolate the models to a high relief environment than to an area with moderate topography on the contrary the models transferred within arctic and subarctic areas were not better than the models between the arctic and subarctic environments in conclusion i region specific geomorphological and environmental conditions may significantly affect the relative importance of variables in gdms ii solifluction models were transferable with certain limitations across areas iii the range of the environmental conditions of the calibration area was a critical factor for transferability success and iv machine learning based methods performed marginally better than parametric models in the model extrapolation extensive knowledge about the transferability of gdms in space is needed before the models can be reliably used in climate change explorations

combining spatial data in landslide reactivation susceptibility mapping a likelihood ratio based approach in w belgium a key issue in landslide susceptibility mapping concerns the relevance of the spatial data combination used in the prediction various combinations of high resolution predictor variables and possibilities of selecting them from a larger dataset are analysed the scarp reactivation of several landslides in a hilly region of w belgium is investigated at the pixel scale the susceptibility modelling uses the reactivated scarp segments as the dependent variable and 13 factors at a 2 m resolution related to topography hydrology land use and lithology as potential independent variables the modelling uses a likelihood ratio approach based on the comparison for each independent variable between two empirical distribution functions edfs respectively for the reactivated and non reactivated areas it uses these edfs as favourability values to build membership values and combine them with a fuzzy gamma operator five different data combinations are tested and compared by analysing the prediction rate curves obtained by cross validation the geomorphological value of the resulting susceptibility maps is also discussed this research shows relevant results for predicting the susceptibility to scarp reactivation we highlight the need for testing several data combinations and underline that combining quantitative criteria with expert opinion is an asset for reliable predictions

effects of large deep seated landslides on hillslope morphology western southern alps new zealand 1 morphometric analysis and air photo interpretation highlight geomorphic imprints of large landslides i e affecting 1 km2 on hillslopes in the western southern alps wsa new zealand large landslides attain kilometer scale runout affect 50 of total basin relief and in 70 are slope clearing and thus relief limiting landslide terrain shows lower mean local relief relief variability slope angles steepness and concavity than surrounding terrain measuring mean slope angle smoothes out local landslide morphology masking any relationship between large landslides and possible threshold hillslopes large failures also occurred on low gradient slopes indicating persistent low frequency high magnitude hillslope adjustment independent of fluvial bedrock incision at the basin and hillslope scale slope area plots partly constrain the effects of landslides on geomorphic process regimes landslide imprints gradually blend with relief characteristics at orogen scale 102 km while being sensitive to length scales of slope failure topography sampling and digital elevation model resolution this limits means of automated detection and underlines the importance of local morphologic contrasts for detecting large landslides in the wsa landslide controls on low order drainage include divide lowering and shifting formation of headwater basins and hanging valleys and stream piracy volumes typically mobilized yet still stored in numerous deposits despite high denudation rates are 107 m3 and theoretically equal to 102 years of basin wide debris production from historic shallow landslides lack of absolute ages precludes further estimates deposit size and mature forest cover indicate residence times of 101 104 years on these timescales large landslides require further attention in landscape evolution models of tectonically active orogens

pedogenesis on the uplands of the diamantina plateau minas gerais brazil a chemical and micropedological study abstract little is known about the soil distribution on quartzitic uplands of brazil the diamantina plateau where deeply weathered oxisols latosols and shallow sandy soils occur side by side represents part of the higher and oldest planation on the quartzitic uplands of minas gerais state we studied representative soils from the diamantina plateau to help understand the pedogenesis and landscape evolution of this part of minas gerais we found evidence of a lithological and tectonic control on the distribution of soils in the landscape polygenetic oxisols acrustox occur at the top of the landscape at altitudes of 1300 m or more resting uncomformably on quartzitic saprocks xanthic types or mafic rocks rhodic types they change downslope to in situ quartzpsamments and haplorthods in the b horizon of the xanthic acrustox quartz grains smaller than 0 3 mm are surrounded by gibbsitic plasma forming subspherical microaggregates microaggregates in the bw horizon of all upland oxisols display inherited features of intense biological activity regardless of the parent material or texture the nutrient poor catena of xanthic acrustox ustic quartzpsamments oxyaquic haplorthods represents a sequence of increasing hydromorphic conditions downwards in which clay minerals are destroyed in low ph and ferrolysis in the poorly drained soils downslope low ph and eh induce the movement of reduced fe 2 and organic matter om bound al and fe both per descendum and through lateral flow downslope in the bottom micromorphological features and the chemistry of organic matter indicated that some bsh horizons represent buried a horizons subjected to post burial podzolization corroborating morphological field data this indicates the pertinence of the study of humic fractions in defining the bhs spodic horizons of brazilian spodosols

the application of gis based logistic regression for landslide susceptibility mapping in the kakuda yahiko mountains central japan as a first step forward in regional hazard management multivariate statistical analysis in the form of logistic regression was used to produce a landslide susceptibility map in the kakuda yahiko mountains of central japan there are different methods to prepare landslide susceptibility maps the use of logistic regression in this study stemmed not only from the fact that this approach relaxes the strict assumptions required by other multivariate statistical methods but also to demonstrate that it can be combined with bivariate statistical analyses bsa to simplify the interpretation of the model obtained at the end in susceptibility mapping the use of logistic regression is to find the best fitting function to describe the relationship between the presence or absence of landslides dependent variable and a set of independent parameters such as slope angle and lithology here an inventory map of 87 landslides was used to produce a dependent variable which takes a value of 0 for the absence and 1 for the presence of slope failures lithology bed rock slope relationship lineaments slope gradient aspect elevation and road network were taken as independent parameters the effect of each parameter on landslide occurrence was assessed from the corresponding coefficient that appears in the logistic regression function the interpretations of the coefficients showed that road network plays a major role in determining landslide occurrence and distribution among the geomorphological parameters aspect and slope gradient have a more significant contribution than elevation although field observations showed that the latter is a good estimator of the approximate location of slope cuts using a predicted map of probability the study area was classified into five categories of landslide susceptibility extremely low very low low medium and high the medium and high susceptibility zones make up 8 87 of the total study area and involve mid altitude slopes in the eastern part of kakuda mountain and the central and southern parts of yahiko mountain

prediction of landslide susceptibility using rare events logistic regression a case study in the flemish ardennes belgium abstract in this article a statistical multivariate method i e rare events logistic regression is evaluated for the creation of a landslide susceptibility map in a 200 km2 study area of the flemish ardennes belgium the methodology is based on the hypothesis that future landslides will have the same causal factors as the landslides initiated in the past the information on the past landslides comes from a landslide inventory map obtained by detailed field surveys and by the analysis of lidar light detection and ranging derived hillshade maps information on the causal factors e g slope gradient aspect lithology and soil drainage was extracted from digital elevation models derived from lidar and from topographical lithological and soil maps in landslide affected areas however we did not use the present day hillslope gradient in order to reflect the hillslope condition prior to landsliding the pre landslide hillslope was reconstructed and its gradient was used in the analysis because of their limited spatial occurrence the landslides in the study area can be regarded as rare events rare events logistic regression differs from ordinary logistic regression because it takes into account the low proportion of 1s landslides to 0s no landslides in the study area by incorporating three correction measures the endogenous stratified sampling of the dataset the prior correction of the intercept and the correction of the probabilities to include the estimation uncertainty for the study area significant model results were obtained with pre landslide hillslope gradient and three different clayey lithologies being important predictor variables receiver operating characteristic roc curves and the kappa index were used to validate the model both show a good agreement between the observed and predicted values of the validation dataset based on a qualified judgement the created landslide susceptibility map was classified into four classes i e very high high moderate and low susceptibility if interpreted correctly this classified susceptibility map is an important tool for the delineation of zones where prevention measures are needed and human interference should be limited in order to avoid property damage due to landslides

evaluation of current statistical approaches for predictive geomorphological mapping abstract predictive models are increasingly used in geomorphology but systematic evaluations of novel statistical techniques are still limited the aim of this study was to compare the accuracy of generalized linear models glm generalized additive models gam classification tree analysis cta neural networks ann and multiple adaptive regression splines mars in predictive geomorphological modelling five different distribution models both for non sorted and sorted patterned ground were constructed on the basis of four terrain parameters and four soil variables to evaluate the models the original data set of 9997 squares of 1 ha in size was randomly divided into model training 70 n 6998 and model evaluation sets 30 n 2999 in general active sorted patterned ground is clearly defined in upper fell areas with high slope angle and till soils active non sorted patterned ground is more common in valleys with higher soil moisture and fine scale concave topography the predictive performance of each model was evaluated using the area under the receiver operating characteristic curve auc and the kappa value the relatively high discrimination capacity of all models auc 0 85 0 88 and kappa 0 49 0 56 implies that the model s predictions provide an acceptable index of sorted and non sorted patterned ground occurrence the best performance for model calibration data for both data sets was achieved by the cta however when the predictive mapping ability was explored through the evaluation data set the model accuracies of cta decreased clearly compared to the other modelling techniques for model evaluation data mars performed marginally best our results show that the digital elevation model and soil data can be used to predict relatively robustly the activity of patterned ground in fine scale in a subarctic landscape this indicates that predictive geomorphological modelling has the advantage of providing relevant and useful information on earth surface processes over extensive areas such data being unavailable through more conventional survey methods

the contribution of termites to the microgranular structure of soils on the uasin gishu plateau kenya abstract the structure of many clay soils in tropical africa is composed of microaggregates that range in size from 0 03 to 1 mm these structural units are often very stable and known as pseudo sand or pseudo silt their presence is detected from the loamy feel of the soil this paper tests the hypothesis that termites contribute to a stable microgranular i e finely aggregated soil structure a termite mound was selected on pedologically unaffected clayey weathering material derived from phonolite the fate of microaggregates produced by termites has been followed through the various stages of mound building field evidence was supplemented with microscopic analysis development of the mound begins when lumps of soil are detached from the subsoil by termites and carried as microaggregates up to the surface in the next stage the microaggregates are cemented to form the nest breakdown begins when the nest is abandoned and disintegrates by splash and runoff producing colluvium or is demolished by ants in the final stage this material is integrated in the soil of the mound soil aggregates produced by splash ants and soil forming processes have different size characteristics but the original microaggregates produced by the termites are preserved in the matrix throughout it is assumed that they owe their stability to impregnation with saliva or other body fluid excreted by the termites termites produce also microaggregates in the form of fecal pellets but these appear to be unstable and are found only in the voids of the soil developed during the last stage

giant landslides topography and erosion abstract distributions of slope angles in tectonically active mountain belts point to the development of threshold conditions where hillslopes attain a critical inclination or height at which they fail readily because of limitations in material strength it has been proposed that hillslopes adjust to rapid uplift and bedrock incision through an increase in the rate of relief limiting landsliding rather than gradual slope steepening here we test this concept by investigating the relationship between mean local relief h which we take to be a proxy of long term erosion rates e and the occurrence of over 300 of the largest v 10 8 m 3 terrestrial landslides on earth we find that nearly two thirds of these giant landslides have occurred in the steepest 5 of the earth s land surface where relief is close to its proposed upper strength limit they are primarily located in deeply incised valleys along fault bounded fringes of active mountain belts and in volcanic arcs this distribution coincides with areas of high long term erosion rates 4 mm yr 1 confirming that giant landslides contribute to rapid denudation of mountains most of the eroded volume is concentrated in the smallest but steepest parts of mountain belts and volcanic arcs first order estimates of minimum erosion rates accomplished by the largest landslides are 0 01 mm yr 1 these rates are between 1 and 10 of the late pleistocene to holocene mean erosion rates in a given area importantly the landslide erosion rates show a nonlinear increase with mean local relief suggesting that the contribution of giant landslides in total and per event increases significantly with increasing overall erosion rates however giant landslides also occur in areas of lower than average relief h 300 700 m irrespective of whether threshold hillslopes have developed or not factors contributing to these failures include soft rocks extensive low angle discontinuities high rates of fluvial bedrock incision and tectonically driven deformation and slope loading

catastrophic landslides glacier behaviour and moraine formation a view from an active plate margin the influence of large bedrock landslides rock avalanches on the behaviour of glaciers is incompletely recognised here we present an example from an active tectonic margin in south island new zealand where large earthquakes leave a significant imprint on glacial records we demonstrate that terminal moraines on the western side of the southern alps record both ordinary i e climate driven and landslide initiated glacial advances following consideration of the processes involved in rock avalanche initiated moraine construction we suggest ways of determining the nature of the advance that built the terminal moraine the implications of these observations are important in breaking the conventional linkage of individual terminal moraines with climate forcing

absence of cooling in new zealand and the adjacent ocean during the younger dryas chronozone as the climate warmed at the end of the last glacial period a rapid reversal in temperature the younger dryas yd event briefly returned much of the north atlantic region to near full glacial conditions the event was associated with climate reversals in many other areas of the northern hemisphere and also with warming over and near antarctica however the expression of the yd in the mid to low latitudes of the southern hemisphere and the southwest pacific region in particular is much more controversial here we show that the waiho loop advance of the franz josef glacier in new zealand was not a yd event as previously thought and that the adjacent ocean warmed throughout the yd

chemical physical and micromorphological properties of termite mounds and adjacent soils along a toposequence in zona da mata minas gerais state brazil article i nfo little is known about the effects of neotropical mound building termites in soil chemical and physical properties the influence of soil termite activity on soil characteristics was studied by assessing chemical physical and micromorphological properties of a toposequence of latosols oxisols soil samples were collected from the walls and inner parts of termite mounds and also from adjacent soil a high diversity of termite genera was found in the mounds along the toposequence together with the inquiline termites and other soil dwelling arthropods chemical analyses showed that ph and the contents of organic c and n p ca and mg were significantly higher in termite mounds compared with adjacent areas with an inverse trend for al content significant differences in ph and exchangeable al were observed between soil and mound across the slopes the mound density across the landscape was higher at the upper slope segment followed by the hill top middle slope and lower slope segments considering a lifespan of 30 years and dimensions of termite mounds found in the toposequence we conclude that the textural and chemical uniformity of latosols may be increased following the pedobiological turnover during mound building with local rates varying from 2 1 to 7 5 m 3 ha 1

suspended sediment flux modeling with artificial neural network an example of the longchuanjiang river in the upper yangtze catchment china artificial neural network ann was used to model the monthly suspended sediment flux in the longchuanjiang river the upper yangtze catchment china the suspended sediment flux was related to the average rainfall temperature rainfall intensity and water discharge it is demonstrated that ann is capable of modeling the monthly suspended sediment flux with fairly good accuracy when proper variables and their lag effect on the suspended sediment flux are used as inputs compared with multiple linear regression and power relation models ann can generate a better fit under the same data requirement in addition ann can provide more reasonable predictions for extremely high or low values because of the distributed information processing system and the nonlinear transformation involved compared with the anns that use the values of the dependent variable at previous time steps as inputs the anns established in this research with only climate variables have an advantage because it can be used to assess hydrological responses to climate change

different landslide sampling strategies in a grid based bi variate statistical susceptibility model abstract this study had three aims the first was to assess the performance of the weights of evidence wofe landslide susceptibility model in areas that are very different in terms of size geoenvironmental settings and landslide types the second was to test the appropriate strategies to sample the mapped landslide polygon the final aim was to evaluate the performance of the method to changes in the landslide sample size used to train the model the method was applied to two areas the fella river basin eastern italian alps containing debris flows and buzau county romanian carpathians with shallow landslides the three landslide sampling strategies used were 1 the landslide scarp centroid 2 points populating the scarp on a 50 m grid and 3 the entire scarp polygon the highest success rates were obtained when sampling shallow landslides as 50 m grid points and debris flow scarps as polygons prediction rates were highest when using the entire scarp polygon method for both landslide types the sample size test using the landslide centroids showed that a sample of 104 debris flow scarps was sufficient to predict the remaining 941 debris flows in the fella river basin while 161 shallow landslides was the minimum required number to predict the remaining 1451 scarps in buzau county below these landslide sample thresholds model performance was too low however using more landslides than the threshold produced a plateau effect with little to no increase in the model performance rates

catastrophic landslide deposits in the karakoram himalaya in july 1986 three catastrophic landslides deposited about 20 x 106 cubic meters of debris on bualtar glacier in the karakoram himalaya a sudden acceleration and superficial breakup of the glacier provided an opportunity to examine the fresh deposits in depth beneath a surface layer of large boulders finer materials mainly sand and silt made up half of the total volume the fine materials were formed during the rock avalanche from mostly intact massive rock of the source zone velocity estimates suggest that this disaggregation occurred in less than 2 minutes coarse materials remained in bands of uniform lithology but the fine materials had diffused throughout the landslides a small amount of carbonate appears to have been calcined by frictional heating presumably at the base of the initial sliding masses these observations are relevant to understanding the mechanisms of catastrophic landslides other nearby rock avalanche deposits indicate that landslides are an important geomorphic process in the area and that they pose a continuing risk to human activity

statistical estimation and generalized additive modeling of rock glacier distribution in the san juan mountains colorado united states 1 our goal is to quantify rock glacier abundance and analyze the topographic controls of rock glacier distribution patterns for this purpose we use statistical estimation techniques and generalized additive models relating rock glacier occurrences to terrain attributes significant applied results include the ability to determine water equivalence and denudation rates the statistical estimation of regional rock glacier abundance based on local interpretation of air photos is an efficient alternative to costly rock glacier inventories these presence absence data n 2933 also allow us to analyze the partly nonlinear topographic controls on rock glacier distribution with generalized additive models we apply these techniques in the san juan mountains 2874 km2 above 3400 m colorado where we obtained a total rock glacier surface area of 70 km2 corresponding to a water equivalence in the order of 0 50 0 76 km3 estimated rock glacier debris volumes imply postglacial denudation rates on the order of 0 5 1 1 mm yr 1 within the talus sheds of rock glaciers the distribution model shows the nonlinear factors of local slope slope of the contributing area local curvature and size of the contributing area controlling the probability of rock glacier occurrence the model yields an area under the receiver operating characteristics curve of 0 91 which indicates an excellent fit on the basis of the present results the integration of terrain attributes with remote sensing data will be the next step toward automatic mapping of rock glaciers in vast mountain areas

mapping landslide susceptibility from small datasets a case study in the pays de herve e belgium a landslide susceptibility map is proposed for the pays de herve e belgium where large landslides affect cretaceous clay outcrop areas based on a bayesian approach this gis supported probabilistic map identifies the areas most susceptible to deep landslides the database is comprised of the source areas of ten pre existing landslides i e a sample of 154 grid cells and of six environmental data layers namely lithology proximity to active faults slope angle and aspect elevation and distance to the nearest valley floor a 30 m resolution dem from the belgian national geographical institute is used for the analysis owing to the small size of the sample a special cross validation procedure of the susceptibility map is performed which uses in an iterative way each of the landslides to test the predictive power of the map derived from the other landslides four different sets of variables are used to produce four susceptibility maps whose prediction curves are compared while the prediction rates associated with the models not involving the proximity to active fault criterion are comparable to those of the models considering this variable strong weaknesses inherent in the fault data on which the latter rely suggest that the final susceptibility map should be based on a model that excludes any reference to fault this highlights the difference between a triggering factor and determining factors and in the same time broadens the scope of the produced map a single reactivated slide is also used to test the possibility of predicting future reactivation of existing landslides in the area finally the need for geomorphological control over the mathematical treatment is underlined in order to obtain realistic prediction maps 2007 elsevier b v all rights reserved

landslide characteristics and slope instability modeling using gis lantau island hong kong steep terrain and high a frequency of tropical rainstorms make landslide occurrence on natural terrain a common phenomenon in hong kong this paper reports on the use of a geographical information systems gis database compiled primarily from existing digital maps and aerial photographs to describe the physical characteristics of landslides and the statistical relations of landslide frequency with the physical parameters contributing to the initiation of landslides on lantau island in hong kong the horizontal travel length and the angle of reach defined as the angle of the line connecting the head of the landslide source to the distal margin of the displaced mass are used to describe runout behavior of landslide mass for all landslides studied the horizontal travel length of landslide mass ranges from 5 to 785 m with a mean value of 43 m and the average angle of reach is 27 7 this gis database is then used to obtain a logistic multiple regression model for predicting slope instability it is indicated that slope gradient lithology elevation slope aspect and land use are statistically significant in predicting slope instability while slope morphology and proximity to drainage lines are not important and thus excluded from the model this model is then imported back into the gis to produce a map of predicted slope instability the results of this study demonstrate that slope instability can be effectively modeled by using gis technology and logistic multiple regression analysis