direct and indirect evaluation of denudation rates in central italy abstract this paper presents the main results of a series of geomorphological studies aimed to the quantitative direct and indirect evaluation of denudation processes in central italy these studies which started in some sample areas since long ago were further deepened and extended to a wider number of drainage basins representative of a variety of morphostructural conditions the complex cause effect relationships among factors influencing both the morphogenesis and the plano altimetric configurations of drainage basins resulted in a large variability in the values of the denudation index tu which ranged from 200 to 2500 t km2 year very high values tu 10 000 t km2 year were obtained for small catchments belonging to the wider basins of ombrone river and tevere river where fast morphological modifications occur due to the action of surface running waters and gravity in the drainage basins affected by the most powerful denudation processes direct measurements of denudation were performed several monitoring stations were equipped with iron stakes and disks to record the local modifications of the topographic surface with time whereas some of these stations have been working continuously since 1993 some others have been running only periodically direct measurements pertinent to periods longer than a decade indicated that mean annual values of denudation range between 1 and 2 5 cm year for slopes affected by sharp edged and or rounded edged badlands higher denudation rates 3 4 cm year were obtained for shorter observation periods still higher rates were recorded for short periods at the gully bottom or in coincidence with mass movements before bench marks were turned up or damaged denudation processes are likely to occur discontinuously they show a step like trend with time and are triggered by rainfall events distributed over a number of consecutive days though not greatly intense particularly their amount should overcome the threshold of 60 mm per 5 consecutive days below this threshold the surface runoff does not seem to reach the power necessary to induce significant modifications of the topographic surface in the study area

development and controlling factors of gullies and gully complexes east coast new zealand sequential aerial photographs of a small headwater catchment in the waiapu basin east coast region north island new zealand were interpreted to measure and analyse temporal changes in active area of gullies and gully complexes for a longer time span 1939 2003 and with higher temporal resolution compared to previous studies we focus on the conditions leading to the development of gullies and gully complexes under pasture and forest by using topographic thresholds slope area relationships of catchments for the initiation of gullies and gully complexes in addition the influence of two different lithologies as well as the occurrence of major rainfall events was related to gully activity twenty gullies and four gully complexes occupying 62 5 ha or 12 5 per cent of the catchment area occurred in the study catchment between 1939 and 2003 however the majority of these were not active at all of the dates studied gullies developed in the sandstone dominated tapuwaeroa formation tended to attain their maximum size by 1957 with a mean catchment area of 2 1 ha gullies developed in mudstone of the whangai formation attained their maximum size in 1939 with a mean catchment area of 4 31 ha exceptions are gullies which developed into mass movement deposits or into an earth flow deposit as well as gullies developed under indigenous forest topographic threshold values for gullies under pasture and indigenous forest show that values for gullies under forest plot far above the threshold line of gullies under pasture indicating that the topographical threshold for gully development under forest is higher compared to under pasture a threshold value of 9 4 ha in catchment area is needed for the development of gully complexes under pasture all located in the whangai formation and with the same orientation as the strike of the mudstones gully complex area and dominance of mass movement erosion increased with larger catchment area a decreasing distance to the threshold line for gullies under pasture indicates a later development for gully complexes no gully complexes developed under indigenous forest indicating that the threshold value for gully complex development is higher than for gully complexes under pasture and was not reached in the study area a model of shifting topographical threshold for gully development for a given catchment is developed which depends on land use when a catchment has an indigenous forest cover the topographical threshold is very high after conversion to pasture threshold values decrease drastically with the invasion of scrub the threshold slowly increases and returns to a similar level to that under indigenous forest after reforestation development of gullies and gully complexes is a highly dynamic phenomenon and phases of expansion and inactivity indicate that models describing only unidirectional advancing stages without periods of inactivity are not suitable therefore this study adds more phases to models of gully and gully complex development in the east coast region the threshold line for gully initiation under pasture and a value of 9 4 ha in catchment area for gully complex initiation permits one to predict which catchments under similar environmental settings develop gullies and gully complexes on a physical basis this enables land managers to implement sustainable land use strategies to reduce erosion rates of gullies and gully complexes copyright 2006 john wiley sons ltd

soil shear strength its measurement and soil detachability abstract recent research on soil erosion mechanics has pointed out that the condition at which rill flow becomes erosive is controlled by soil surface shear strength torri et al 1987a rauws govers 1988 also splash detachment processes are strictly linked to soil shear strength as shown by nearing bradford 1985 torri et al 1987b a comparison of the proposed threshold conditions for incipient rilling immediately shows that they differ in the two quoted papers the same situation characterizes the relations proposed between splash detachment and soil shear strength those differences may depend on the different instruments used for measuring soil shear strength a geonor model g 200 laboratory cone penetration apparatus a laboratory vane tester and a pocket vane tester those instruments differ in shape pocket and laboratory vane testers or in the physics involved in their functioning vane tester and drop cone penetrometer the experimental results show that the drop cone penetrometer is characterized by a low repeatability moreover it is sensitive to small variations in soil texture the laboratory vane apparatus seems to determine a surface of shear close to that of a sphere circumscribed to the vane the pocket vane apparatus instead is characterized by a cylindrical surface of shear those results seem to explain the main differences in soil detachment in particular incipient rilling conditions are clearly reduced to a single relation between critical shear velocity and soil shear strength it can consequently be concluded that soil detachability is strictly linked to soil shear strength

space time variability of denudation rates at the catchment and hillslope scales on the tyrrhenian side of central italy studies on denudation rates can provide insight into the influence of climate change tectonics and human activities on landscape evolution research performed in central italy has shown considerable spatial variability of denudation rates in the major river basins these studies have focused mainly on the tyrrhenian side of the italian peninsula where plio pleistocene marine deposits filling nw se elongated sedimentary basins have been uplifted during the quaternary up to several hundreds of meters above present sea level small sub catchments developed on clays are affected by sharp and or rounded edged badlands i e calanchi and biancane representing denudation hot spots in the present day morphoclimatic framework in this paper we analyze the relationships between indirectly estimated denudation rates at the catchment scale and field monitoring data at the hillslope scale we attempt to better understand and quantify all hillslope processes that contribute to seasonal variability of denudation to help with predicting the net input from hot spots to the overall estimated sediment yield at the basin outlets at the hillslope scale we discuss in particular the variability of denudation rates at calanchi and biancane badlands as a function of their different morphoevolution

eocene seasonality and seawater alkaline earth reconstruction using shallow dwelling large benthic foraminifera abstract intra test variability in mg ca and other trace elements within large benthic foraminifera lbf of the family nummulitidae have been investigated using laser ablation inductively coupled plasma mass spectrometry la icpms these foraminifera have a longevity and size facilitating seasonal proxy retrieval and a depth distribution similar to surface dwelling planktic foraminifera coupled with their abundance in climatically important periods such as the paleogene this means that this family of foraminifera are an important but under utilised source of palaeoclimatic information we have calibrated the relationship between mg ca and temperature in modern operculina ammonoides and observe a 2 increase in mg ca c 1 o ammonoides is the nearest living relative of the abundant eocene genus nummulites enabling us to reconstruct mid eocene tropical sea surface temperature seasonality by applying our calibration to fossil nummulites djokdjokartae from java our results indicate a 5 6 c annual temperature range implying greater than modern seasonality in the mid eocene bartonian this is consistent with seasonal surface ocean cooling facilitated by enhanced eocene tropical cyclone induced upper ocean mixing as suggested by recent modelling results analyses of fossil n djokdjokartae and operculina sp from the same stratigraphic interval demonstrate that environmental controls on proxy distribution coefficients are the same for these two genera within error using previously published test seawater alkaline earth metal distribution coefficients derived from an lbf of the same family raitzsch et al 2010 and inorganic calcite with appropriate correction systematics for secular mg casw variation evans and muller 2012 we use our fossil data to produce a more accurate foraminifera based mg casw reconstruction and an estimate of seawater sr ca we demonstrate that mid eocene mg casw was 2 mol mol 1 which is in contrast to the model most commonly used to correct deep time mg ca data from foraminifera but in agreement with most other paleogene proxy and model data this indicates that mg casw has undergone a substantial 3 4 rise over the last 40 ma

characteristics and controlling factors of old gullies under forest in a temperate humid climate a case study from the meerdaal forest central belgium abstract in many forests of northwestern europe old gullies can be found but few studies have reported their genesis and characteristics this study investigates these old gullies under forest in the large case study area of meerdaal forest in the central belgian loess belt the objectives are 1 to determine the spatial distribution of these gullies 2 to measure their morphological and topographical characteristics and 3 to reconstruct the factors that led to their development in the 1329 ha study area 252 channel like incisions were mapped different types of incisions could be distinguished besides small and large gullies many incisions were sunken lanes or road gullies these road gullies are aligned along north south oriented lines whereas the concentration of old gullies is strongly related to the distribution of archaeological sites out of the 252 mapped incisions 43 large gullies and 21 representative road gullies were selected for detailed morphological and topographical measurements the characteristics of these two types of incisions were compared with ephemeral gullies formed under nearby cropland significant differences in morphology between the three types could be demonstrated ephemeral gullies under cropland and large gullies under forest differ significantly in all measured parameters except bottom width both the old gullies and road gullies under forest have a significantly larger cross section and total eroded volume compared with the ephemeral gullies observed under cropland this indicates that once formed the old gullies were not ploughed in nor were they filled by sediment originating in their drainage areas because of limited sediment production comparing topographical characteristics i e slope at the gully head and runoff contributing area of forest gullies and ephemeral gullies that formed under cropland yields important indications about their formation the larger sedimentation slope of forest gullies compared with ephemeral gullies and road gullies suggests that the forest gullies incised on vegetated slopes as a consequence of runoff from the adjacent plateau where the forest cover was disturbed for the old gullies under forest no relation between slope at the gully head and runoff contributing area is observed probably because most gullies occur on very steep slopes when simulating arable land use in the study area zones where ephemeral gullies are expected to develop can be predicted using published topographical threshold relationships comparing the zones where ephemeral gullies are predicted with the position of old gullies under forest leads to the conclusion that gully incision was most probably not triggered by extreme rainfall events and that they are not of periglacial origin the observed gully pattern can best be explained by local anthropogenically determined land use changes

geomorphic features of a badland biancane area central italy characterisation distribution and quantitative spatial analysis abstract the biancana landscapes rather common in several italian areas have a very complex morphology different geomorphic features often occur along the same hillslope from a morphological survey of an experimental site in southern tuscany the forms were classified and their distribution analysed spatial analysis of the biancane provided insights into the range of forces responsible for their formation and evolution the results confirm an evolutionary trend from an original gently sloping surface to a complex biancana landform emphasising a trend from the taller bean forms to the terminal souffle like and cone forms the presence of scarp and sliding forms in the most sloping areas and along the residual surfaces supports the hypothesis of a process influenced by base level acting initially by small mass movements spatial analysis did not reveal any systematic trend in the variability of the erosional features along the slopes variographic analysis showed that selected morphological attributes are spatially auto correlated over a short range suggesting that the erosive processes responsible for morphogenic evolution of biancane act mostly on a local scale the strong geometric anisotropy detected in directions parallel to the main jointing systems also indicated a broader scale tectonic control of biancane evolution probably in an early stage of their formation

nummulitic banks in the upper lutetian buil level ainsa basin south central pyrenean zone the impact of internal waves nummulites a particularly abundant and diverse genus of larger benthonic foraminifera formed huge accumulations banks during the eocene which are often good hydrocarbon reservoirs especially in north africa despite their economical interest these accumulations are not well understood and their origin is still under discussion reasons for this debate are the absence of living nummulites accumulations and the high variability of facies including the size shape and extension of the banks which reflect the array of processes controlling sediment production and accumulation the nummulitic banks near santa maria de buil in the ainsa basin south pyrenean foreland basin are composed of recurrent facies associations within mappable bed units bounded by physical surfaces the depositional processes that produced the nummulites deshayesi accumulations are interpreted considering the shape of the banks the type of bounding surfaces the distribution of sedimentary textures nummulites test shapes and the associated skeletal components within the banks this integrative analysis indicates that nummulitic banks accumulated from mass flows with very poor sediment sorting textural and compositional differences among banks suggest that globose nummulites thrived in the shallower part of the mesophotic zone with abundant nummulithoclasts whereas flat nummulitic forms thrived in deeper mesophotic clay dominated settings interbedded with nummulitic banks coral biostromes and coral mounds bearing operculina discocyclina and asterocyclina represent in situ accumulation near the base of the photic zone internal waves waves that propagate along the pycnocline are thought to be the triggering mechanism for the density flows internal waves and induced bottom currents are sporadic but strong enough to bring sediments into suspension in contrast to surface waves both fair weather and storm whose impact is strongest near the sea surface and decreases with bathymetry the impact of internal waves is usually strongest in the mid shelf region and weaker in shallow water this explains the compositional character of the nummulitic banks

stable isotopes in recent larger foraminifera abstract oxygen and carbon isotope analyses have been made on large benthic foraminifera from bermuda the persian gulf and the philippines the foraminifera belong to the two suborders rotallina and miliolina life spans range between one season to more than two years shells contain information about seasonal temperature ranges and life history stages recorded as fluctuations of oxygen and carbon isotopic values within the shell material almost all specimens studied showed the expected variations in 18o with respect to ambient conditions water isotopic composition and seasonal temperature fluctuations the specimens from bermuda seemed enriched in 18o whereas all specimens from the philippines independent of their taxonomic position seemed to the depleted in 18o with respect to calcita equilibrium specimens from the same species showed about the same level and range of 18o values the miliolid species marginopora vertebralis cyclorbiculina compressa archaias angulatus peneroplis proteus and praesorites orbitolitoides cf monensis commonly show carbon isotope values up to 2 5 lighter than expected equilibrium values independent of sample locality the rotaliid species heterostegina depressa operculina sp and calcarina spengleri show carbon isotope values more than 2 lighter than expected equilibrium values also independent of sample locality all analyzed miliolid species show a tendency with age towards lighter than equilibrium 13c values the analyzed rotaliid species showed the reverse that is shells tend toward increased 13 values with age

the value of a physically based model versus an empirical approach in the prediction of ephemeral gully erosion for loess derived soils abstract a data set on soil losses and controlling factors for 58 ephemeral gullies has been collected in the belgian loess belt from march 1997 to march 1999 of the observed ephemeral gullies 32 developed at the end of winter or in early spring winter gullies and 26 ephemeral gullies developed during summer summer gullies the assessed data have been used to test the physically based ephemeral gully erosion model egem and to compare its performance with the value of simple topographical and morphological indices in the prediction of ephemeral gully erosion analysis shows that egem is not capable of predicting ephemeral gully cross sections well although conditions for input parameter assessment were ideal some parameters such as channel erodibility critical flow shear stress and local rainfall depth showed great uncertainty rather than revealing egem s inability of predicting ephemeral gully erosion this analysis stresses the problematic nature of physically based models since they often require input parameters that are not available or can hardly be obtained with respect to the value of simple topographical and morphological indices in predicting ephemeral gully erosion this study shows that for winter gullies and summer gullies respectively over 80 and about 75 of the variation in ephemeral gully volume can be explained when ephemeral gully length is known moreover when previously collected data for ephemeral gullies in two mediterranean study areas and the data for summer gullies formed in the belgian loess belt are pooled it appears that one single length l volume v relation exists v 0 048 l 1 29 r 2 0 91 these findings imply that predicting ephemeral gully length is a valuable alternative for the prediction of ephemeral gully volume a simple procedure to predict ephemeral gully length based on topographical thresholds is presented here secondly the empirical length volume relation can also be used to convert ephemeral gully length data extracted from aerial photos into ephemeral gully volumes

winners and losers stable isotopes and microhabitats of living archaiadae and eocene nummulites larger foraminifera abstract this paper discusses isotopes in larger foraminiferal calcite from two contrasting settings modern florida bay dominated by archaiadae the winners and the upper eocene barton clay of england locally dominated by nummulites the losers the archaiads plus peneroplids and soritids were mainly collected from thalassia leaves they yield signatures that closely reflect strong isotopic gradients in sea water across florida bay and the outer patch reefs isotopic signatures of eurytopic androsina lucasi record extreme conditions to the north of the bay which includes 13 c evidence for much nutrient regeneration such tolerance of relatively eutrophic conditions may explain the capacity of archaiadae for survival in the caribbean region during the neogene isotopes of nummulites prestwichianus from the basal bartonian compare more closely with data from living nummulite heterostegina 18 o indicates a yearly growth cycle under tropical bottom water temperatures with an annual range of approximately 2 5 c carbon isotopes show a trend towards heavier values with growth here related to decelerating rates of calcification and perhaps the additional effects of test thickening on carbon isotope fractionation by endosymbionts the nummulitic data indicate a much more stable carbon and nutrient cycle in the basal barton clay than seen in the florida bay mudmound assemblage this is consistent with their presumed stenotopic and oligotrophic life habit it could well explain their vulnerability to extinction after the mid eocene and the post aquitanian decline of larger rotaliids and reefs in the caribbean region

predicting the topographic limits to a gully network using a digital terrain model and process thresholds a digital terrain model is used with process thresholds to predict the extent of a stable gully network in a 5 km2 catchment of the southeastern highlands of australia the model developed by dietnch et al 1992 1993 predicts the topographic controls on channel networks and interprets these in terms of a critical shear stress for channel incision c applied by saturation overland flow we adapt the model slightly to compare the shear stress applied by hortonian overland flow to that applied by saturation overland flow the limits to gully erosion in the catchment are controlled strongly by a topographic threshold that has an inverse relationship between upslope catchment area and local gradient the topographic threshold for channel incision is reproduced using a simple model of hortonian overland flow and a c appropriate for incision into a degraded grass surface c 245 dyn cm2 this is consistent with historical evidence for the timing of gully erosion the study confirms a strong topographic control on the extent of the channel network in a catchment significantly different from the western north america catchments where the topographic threshold was first demonstrated despite its simplicity the model for incision by overland flow appears capable of distinguishing the hydrological processes responsible for channel incision when these are reflected in the relationship between channel network and landscape morphology the model requires relatively simple inputs suggesting it may be useful for mapping gully erosion hazard in actively eroding catchments

factors controlling the spatial distribution of soil piping erosion on loess derived soils a case study from central belgium abstract collapsible loess derived soils are prone to soil piping erosion where enlargement of macropores may lead to a subsurface pipe network and eventually to soil collapse and gully development this study aims at understanding the main factors controlling spatial patterns of piping in loess derived soils under a temperate climate to map the spatial distribution of piping and identify the environmental controls on its distribution a regional survey was carried out in a 236 km2 study area in the flemish ardennes belgium orthophotos taken at optimal field conditions winter were analyzed to detect piping in open landscapes and ground thruthing was systematically done through field surveys in total 137 parcels having 560 collapsed pipes were mapped dimensions of the sinkholes and local slope gradient were measured in the field and topographical variables were derived from lidar data land use plays an important role as 97 of the sites with piping are found under pasture the probability of piping increases rapidly on hillslopes with gradients exceeding 8 and with a concave profile and plan curvature enhancing subsurface flow concentration the zones with soil profiles on shallow loess over a relatively thin layer of homogeneous blue massive clays aalbeke member are most prone to piping soil characteristics are of less importance to explain piping occurrence furthermore the topographical threshold line indicating the critical slope gradient for a given contributing drainage area was determined this threshold line negative power relation is similar to the threshold line for shallow gully initiation

observed and modelled distributions of channel and gully heads with examples from se spain and belgium abstract in soil erosion by overland flow sediment discharge is driven by discharge and gradient against the resistance of the soil and vegetation the form of the relationship which is taken as a sum of power law terms may then be inferred from several data sources 1 ephemeral gully head location 2 permanent channel head location 3 slope profile form 4 consistency with evolutionary models and 5 erosion plot data the paper focuses on 1 to 4 in order to understand how far these data constrain the form of the dependence on discharge and gradient field data from mapping a set of ephemeral gully heads after storms show a weak inverse relationship between channel head gradient and catchment area which flattens towards an upper threshold gradient of about 25 these relationships are compared with those theoretically obtained for a range of sediment transport laws which have been previously used and which are analysed to forecast both overall slope profile form and the location of stream heads the theory predicts that the location of ephemeral gully heads produced in a single storm will differ from the long term average stream head location there is a fairly good relationship between theoretical and observed locations associated with the form of the sediment transport law for a single event the location depends on storm magnitude which cannot be well defined from the data sets creating a spread of data with an envelope curve defined for the largest events the empirically acceptable sediment transport equations have also been used to analyse families of slope profiles in a small area and used within a landscape evolution model to generate landscapes which are compatible with those observed in the field and provide confirmation of the long term viability of the expressions obtained to forecast the direction style and rates of landscape evolution in response to land use or climate drivers

the recurring cycles of biancana badlands erosion vegetation and human impact abstract the biancana badlands a typical element of the southern tuscany landscape were in expansion for centuries until bulldozers began erasing them for land reclamation purposes over the last 10 15 years some of the scattered remnants of biancanas have been placed under protection in order to preserve their biodiversity and their particular cultural and geomorphological landscapes rural abandonment and the lack of appropriate management practices have contributed to vegetation encroaching on biancana badland slopes causing a loss of elements of high ecological and cultural values as well as eroded spots the aim of this paper is to explore the direction and rate of change in land use of the biancana badland landscapes over the last 50 years evaluating the erosion vegetation dynamics and examining the processes involved in two biancana badlands lucciola bella and crete di camposodo crete di leonina which are sites of community importance first we analysed the landscape changes that occurred in the biancana areas from 1954 to 2005 comparing old and recent land use maps twinspan classification was applied on selected plots of a plant dataset to distinguish vegetation types and identify the indicator species of each different type we then evaluated soil erodibility on the eroded biancana surfaces regosols and well developed vertisols which represent the coexisting extremes of the soil situation within the biancana badlands we empirically assessed the effects of a few roots on saturated soil shear strength to introduce direct links between plants and soil processes our results showed a decrease in bare or scarcely vegetated spots of 0 9 ha y 1 if the encroachment continues to progress at this rate in 35 40 years from now all the biancana domes will be completely re vegetated encroachment on the most eroded biancanas was mainly ascribed to generalist ruderal species such as avena fatua and dactylis glomerata we showed that rills and subsurface micropipes are characterized by the same erosion processes meaning that they can be contrasted and eventually halted by the same means and we observed a clear positive trend that will substantially suppress rilling at very low plant cover no more than 20 badlands were previously kept alive by limited but nonetheless devastating grazing activities if this picture is correct then mimicking traditional badland grazing practices seems to be a necessary step towards saving the landscape and biodiversity that the protected areas were established to preserve

ecology of extant nummulitids and other larger benthic foraminifera applications in palaeoenvironmental analysis abstract larger benthic foraminifera lbf are important contributors to modern and ancient tropical shallow marine sediments over the past 30 years a substantial body of literature has built up on the ecology of modern lbf especially in terms of their environmentally sensitive depth distribution reproductive strategy and morphology and the symbiotic relationship between many larger foraminifera and photosynthetic algae over the same period the extinct genus nummulites which is abundant in eocene sediments of southern europe north africa and the arabian peninsula has increasingly been studied principally because significant volumes of hydrocarbons have been discovered reservoired within nummulitic limestones offshore tunisia and libya the modern ecological studies of lbf provide a powerful tool with which to develop palaeoecological models for fossil nummulites and other symbiont bearing larger foraminifera in the rock record

preliminary study of the erosion mechanisms in a biancana badland tuscany italy abstract italian badlands are present along the appennini mountains with an annual precipitation which ranges from 400 to 1200 mm the genesis of these badlands has often been studied whereas current processes and erosion rates have only rarely been examined and measured this paper describes a preliminary study on a badland developed in temperate mediterranean climate and located in sw tuscany italy the selected site is characterized by biancane dome shaped features a few meters in height generally having a vegetated nne aspect and severely eroded ssw slope with a sub horizontal basal pediment field rainfall and runoff experiments were carried out field results were substantiated by data collected in specially devised laboratory tests it was concluded that near surface pipes which develop at the point of contact between a surficial layer of weathered and severely fractured regolith and the less fractured and weathered regolith underneath are the main drainage channels while rills play a secondary role soil detachment is largely due to mechanical and chemical slaking of the regolith during infiltration the role of runoff is almost solely transport in particular it was found that the runoff detachment rate is limited by the rate at which the water front penetrates into the regolith

badlands denudation hot spots the role of parent material properties on geomorphic processes in 20 years monitored sites of southern tuscany italy abstract some monitoring stations have been recording for 20 years the geomorphic processes acting on calanchi and biancane badlands located in the tyrrhenian side of central italy field monitoring was aimed at studying the dynamics of surface processes such as sheet rill and gully erosion shallow landsliding piping and tunneling considering their space time variability as a consequence of both natural factors and human pressure this paper shows the results of grain size geochemical and mineralogical composition of parent materials from upper orcia valley sites southern tuscany to further elucidate the role of their properties on processes acting on both bare and vegetated surfaces parent materials properties are discussed with respect to the initiation and development of different badlands processes in particular clay dispersivity at different depths in the sample sites is examined as a well known controlling factor of accelerated erosion thus providing some interesting clues for understanding the spatial variability of denudation rates in the considered badlands sites

geochemical transport modelling of drainage from experimental mine tailings cells covered by capillary barriers the use of covers with capillary barrier effects ccbes for reducing acid mine drainage amd from sulphidic mine tailings is simulated using the min3p finite volume model for coupled groundwater flow o2 diffusion and multi component reactive transport the model is applied to simulate five pilot scale in situ test cells containing reactive tailings from the manitou mine site val d or que canada four of the cells were constructed with ccbes over the tailings while the fifth tailings cell was left uncovered observed and simulated discharge from the base of each cell showed that the capillary barrier covers significantly reduced sulphide oxidation and amd compared to acidic discharge from the uncovered cell discharge from the four ccbe covered cells had neutral ph levels and 1 7 orders of magnitude lower concentrations of so4 fe zn cu and al the simulations showed that the moisture retaining layer of the ccbes reduced amd by inhibiting o2 diffusion into the underlying reactive wastes provided the moisture retention layer of the ccbe remains close to saturation its thickness had a relatively minor effect under such near saturated conditions o2 availability is limited by its diffusion rate through the bulk porous medium and not by the diffusion rate through the oxidized grain shells the model is providing important new insights for comparing design alternatives for reducing or controlling amd

stable isotope composition of benthic foraminifera from the equatorial pacific when ranked according to deviation from isotopic equilibrium deep sea benthic foraminifera exhibit no correlation between the rankings for oxygen and for carbon both rank sequences are stable from east to west in the equatorial pacific fertility independent and from glacial to post glacial time independent records for the past 15 000 yr suggest marked changes in deep sea circulation during this time interval