role of equatorially asymmetric sea surface temperature anomalies in the indian ocean in the asian summer monsoon and el nino southern oscillation coupling using an ocean general circulation model forced by daily mean wind stresses and heat fluxes derived from the bulk formulation with the national centers for environmental protection national center for atmospheric research reanalysis we examined possible roles of the tropical indian ocean in the asian summer monsoon and el nino southern oscillation enso coupling a dominant precursory signal of anomalous monsoon circulation relevant to enso is the presence of latitudinally asymmetric anomalies of tropical convection and sea surface temperature sst near the equator in the preceding spring the model results show that the equatorial asymmetry of surface latent heat flux plays a vital role in generating the equatorially asymmetric sst in the preceding spring which implies that a positive wind evaporation sst wes feedback proposed by xie and philander 1994 is crucially responsible for generation and maintenance of those equatorial asymmetries the westward extension of anomalous convection from the vicinity of the philippines into the northern indian ocean from the preceding winter to spring which has a signal of enso can be viewed as a developing process of wes persistence of the wes feedback regime affects land surface hydrologic processes in the asian continent through a rossby wave response to anomalous convective heating it is anticipated that the wes mode in the tropical indian ocean serves as a bridge between the enso prevailing in the preceding winter and the anomalous summer monsoon

asymmetry of the indian ocean basinwide sst anomalies roles of enso and iod abstract a basinwide warming cooling in the indian ocean is observed following the el nino la nina mature phase with the amplitude of the warming being significantly larger than the cooling a composite analysis reveals that the amplitude asymmetry positive skewness between the warm and cold indian ocean basinwide sea surface temperature anomaly pattern iob appears only when enso is concurrent with the indian ocean dipole iod the amplitude asymmetry becomes insignificant during the enso only and the iod only events the physical mechanism for the amplitude asymmetry is investigated by analyzing the mixed layer heat budget based on the simple ocean data assimilation soda 2 0 2 data it is found that the positive skewness in the iod west pole iodw is mainly caused by the asymmetry of ocean temperature advection whereas the positive skewness in the iod east pole iode is caused by the asymmetry of the surface heat flux anomaly primarily shortwave radiation in response to the enso remote f

geomorphometric assessment of spatial sediment connectivity in small alpine catchments abstract complex and rugged topography induces large variations in erosion and sediment delivery in the headwaters of alpine catchments an effective connection of hillslopes with the channel network results in highly efficient sediment transfer processes such as debris flows in contrast morphological conditions producing decoupling of hillslopes from channels e g glacial cirques may exclude large areas of the catchment from sediment delivery to its lower parts moreover an efficient connection between hillslopes and channel network does not always ensure an effective downstream transfer of sediment low slope channel reaches e g in hanging valleys cause sediment deposition which often results in changes of the sediment transport processes typically from debris flow to streamflow with low bedload and suspended load rates the availability of high resolution digital terrain models such as those derived from aerial lidar improves our capability to quantify the topographic controls on sediment connectivity a geomorphometric index based on the approach by borselli et al 2008 was developed and applied to assess spatial sediment connectivity in two small catchments of the italian alps featuring contrasting morphological characteristics the results of the geomorphometric analysis were checked against field evidences showing good performance and thus potential usefulness of the index

influences of enso teleconnection on the persistence of sea surface temperature in the tropical indian ocean abstractthis study confirms a weak spring persistence barrier spb of sea surface temperature anomalies sstas in the western tropical indian ocean wio a strong fall persistence barrier fpb in the south china sea scs and the strongest winter persistence barrier wpb in the southeastern tropical indian ocean seio during el nino events a less abrupt sign reversal of sstas occurs in the wio during spring an abrupt reversal occurs in the scs during fall and the most abrupt reversal occurs in the seio during winter the sign reversal of ssta implies a rapid decrease in ssta persistence which is favorable for the occurrence of a persistence barrier the present results indicate that a more abrupt reversal of ssta sign generally corresponds to a more prominent persistence barrier el nino induced changes in atmospheric circulation result in reduced evaporation and suppressed convection this in turn leads to the warming over much of the tio basin which is an important mechanism for the abrupt

measuring gullies by synergetic application of uav and close range photogrammetry a case study from andalusia spain abstract gullies naturally exhibit complex morphologies and hence are difficult to measure photogrammetric methods are promising tools to overcome such problems due to 3d reconstruction from overlapping images without disturbing the surface airborne e g unmanned aerial vehicles uav and terrestrial image acquisition platforms are possible data sources for comprehensive digital gully modelling in this study an approach for the synergetic utilisation of uav and terrestrial images for high resolution 3d model generation is introduced while proper uav mission planning is necessary terrestrial images can be acquired spontaneously and flexibly depending on the encountered terrain conditions to supplement uav data without confining accuracy demands terrestrial images are processed solely with additional information from already existent 3d models and orthophotos from uav image processing during this field campaign uavs are suitable for flexible and frequent gully monitoring however with the case specific flight configuration 3d modelling is restricted at steep gully walls above slope gradients of 50 60 as well as overhanging gully walls due to the limiting birds eye view additional terrestrial images are used to overcome these limitations and fill up data gaps in this study the final merged digital gully model reveals a resolution about 0 5 cm and an accuracy of 1 cm a gully headcut in andalusia spain is analysed to confirm the suitability of the synergetic data utilisation a study period of three months during winter season is investigated to measure multi temporal 3d volume changes the positive volume balance amounts to 5 m 3 for a gully area of 170 m 2 and is caused mainly by anthropogenic interactions concluding the combination of uav and terrestrial data allow for comprehensive gully models with high spatial resolution at frequent intervals

thirty years of studies on badlands from physical to vegetational approaches a succinct review the scientific subjects addressed in the research into badlands since the publication of bryan and yair s book bryan r b and yair a editors 1982 badland geomorphology and piping geo books norwich 408 pp are briefly analysed with a steadily increasing number of papers per year attention to some aspects such as runoff generation piping and the role of lithology and soils varied whereas the percentage of studies on erosion rates increased steadily over time vegetation was not a subject of research in early papers as most of the papers dealing with vegetation were rather descriptive and published in local or limited diffusion media which contrasts with the present situation when about 40 of papers published in international journals about badlands address some aspect of vegetation however the growth in the attention paid to vegetation and erosion rates was not linked to any increase in papers dealing with badland reclamation badlands are now seen as a group of systems with some common features but diverse dynamics depending mainly on climatic and lithological drivers more attention should be paid in the future to investigating the evolution of these landforms over time mostly through modelling studies whereas emerging technologies foster detailed analyses that were not possible formerly although some badland areas determine on and off site environmental issues others are spots of landscape diversity that merit protection rather than reclamation

hyperscale terrain modelling of braided rivers fusing mobile terrestrial laser scanning and optical bathymetric mapping quantifying the morphology of braided rivers is a key task for understanding braided river behaviour in the last decade developments in geomatics technologies and associated data processing methods have transformed the production of precise reach scale topographic datasets nevertheless generating accurate digital elevation models dems remains a demanding task particularly in fluvial systems this paper identifies a threefold set of challenges associated with surveying these dynamic landforms complex relief inundated shallow channels and high rates of sediment transport and terms these challenges the morphological wetted channel and mobility problems respectively in an attempt to confront these issues directly this paper presents a novel survey methodology that combines mobile terrestrial laser scanning and non metric aerial photography with data reduction and surface modelling techniques to render dems from the resulting very high resolution datasets the approach is used to generate and model a precise dense topographic dataset for a 2 5 km reach of the braided rees river new zealand data were acquired rapidly between high flow events and incorporate over 5 x 109 raw survey observations with point densities of 1600 pts m 2 on exposed bar and channel surfaces a detailed error analysis of the resulting sub metre resolution is described to quantify dem quality across the entire surface model this reveals unparalleled low vertical errors for such a large and complex surface model between 0 03 and 0 12 m in exposed and inundated areas of the model respectively copyright 2013 john wiley sons ltd

badland dynamics in the central pyrenees temporal and spatial patterns of weathering processes the genesis and development of badlands is controlled by bedrock lithology topography and climate the development of badlands in the central spanish pyrenees is favoured by the presence of marls and a climate with a marked seasonality the combination of these factors results in active hydrosedimentological processes the aim of the present work was to study the dynamics of badlands in the central pyrenees with a focus on the temporal and spatial patterns of the dominant weathering processes the study area was a small mountain catchment and we focussed on the continuous observation of a number of physical parameters that control regolith development and weathering processes samples collected from different depths at sites with different aspects enabled temporal comparisons of the factors involved in the development of surface regolith that can be considered as indicators of the weathering of the marls these indicators were then related to environmental variables moisture and temperature atterberg limits were established and related to moisture content to explain slope dynamics and related processes finally analyses of carbonate content were performed in the laboratory the results validate the employed methodology supporting our description of weathering processes the established chronological sequence and the relation of these processes to climatic and topographic parameters the results obtained since january 2004 show that the chosen indicators are sensitive to seasonal dynamics variations in temperature and water supply and slope aspect the development and dynamics of regolith on north facing slopes is more active than that on south facing slopes freeze thaw is the main weathering process on north facing slopes while south facing slopes are dominated by the development of crusts associated with wetting drying processes washing effects and lower temperatures upon north facing slopes mean that the dissolution of carbonates is more pronounced in such areas compared with south facing slopes especially within the upper layers of the regolith copyright 2006 john wiley sons ltd

exploring the initial errors that cause a significant spring predictability barrier for el nino events 1 within the zebiak cane model we identify two types of initial errors that have significant season dependent evolutions related to the spring predictability barrier spb for el nino events one type includes the sea surface temperature anomaly ssta errors that have a zonal dipolar pattern with positive anomalies in the central equatorial pacific and negative ones in the eastern equatorial pacific the other type consists of the ssta errors with a spatial structure opposite to that of the former type the zonal dipolar pattern shows negative anomalies in the central equatorial pacific and positive anomalies in the eastern equatorial pacific the patterns of these two types of errors are nearly opposite of each other the former causes the el nino event to be underpredicted and the latter causes the el nino event to be overpredicted for strong el nino events the former tends to have a larger effect on the predictions than the latter but for weak el nino events it is very difficult to determine which type of initial errors results in worse predictions it is thought that strong weak el nino events could be affected by strong weak nonlinearities there are also other initial errors however they do not yield considerable season dependent evolutions nor can a common characteristic be extracted from their patterns the two types of initial errors suggest two dynamical behaviors of error growth related to the spb in one case the initial errors grow in a manner similar to the el nino events in the other case the initial errors develop with a tendency opposite to the el nino events the two types of initial errors may capture the errors that exhibit significant season dependent evolutions related to the spb in addition they may provide information regarding the sensitive area of enso predictions because of their localized regions therefore if these types of initial errors exist in the realistic el nino southern oscillation enso predictions and if a data assimilation or a target method can filter them the enso forecast skill may be improved for ensemble forecast studies different signs of prediction errors caused by the two types of initial errors could illustrate why the ensemble mean offers a better forecast than a single prediction

monitoring and modelling morphological change in a braided gravel bed river using high resolution gps based survey recent research in fluvial geomorphology has emphasized the direct monitoring of channel topography as a useful tool to better understand the interrelationship between river form and process and in particular to estimate bedload transport rates and reach scale sediment budgets until recently however this morphometric approach has been limited to comparison of repeatedly surveyed cross sections with the associated problems of low frequency sampling and an emphasis on cross stream as opposed to downstream morphological dynamics recent advances in analytical photogrammetry have however permitted the acquisition of data at sufficient resolutions to represent macroform 101 m and microform 10 m channel geometry in fully three dimensions while inherently spatially distributed the photogrammetric approach to land surveying is however restricted to observable areas of the channel and is thus of limited use in the subaqueous zone especially if flows are turbid or highly coloured this paper presents an alternative approach to the study of three dimensional morphological dynamics of a divided reach of the gravelly river feshie scotland in which topographic survey of both exposed and submerged areas of the reach was undertaken using the global positioning system gps survey results from two field programmes in 1998 and 1999 are presented in which a geotronics geotracer 2000 real time kinematic gps receiving unit was used to survey a 200 80 m reach rapid radial survey methods were employed permitting the collection of 2000 survey points per day giving a mean density over the 13 ha reach of 1 1 points per square metre a detailed assessment of survey errors and dem quality is presented and a limit of detection of c 10 cm proposed as an upper threshold for the identification of significant change between dems preliminary interpretation of channel dynamics in 1998 99 reveals relatively little change to the overall macroscale reach structure dem differencing techniques however highlight important local changes including the progradation of submerged bar fronts bar head aggradation and scour along major channel thalwegs and the erosion of fines from sloughs copyright 2000 john wiley sons ltd

erosion rates in badland areas of the central ebro basin ne spain abstract erosion rates have been estimated for two badland areas in the ebro basin el barranco and la charca plots using direct measurement techniques these measurements were made by means of erosion pins and a microtopographic profile gauge measurements with erosion pins at the el barranco plot indicate highest erosion rates around rills and at rill junctions in contrast at the la charca plot only small differences between erosional rates for rill and interrill areas are observed microtopographic profiles carried out in el barranco show irregular ground lowering greater in rill than in interrill areas at la charca similar denudation rates are observed in rill and interrill areas erosion rates determined with the microtopographic profile gauge were 7 and 19 mm year in el barranco and la charca plot respectively and close to 6 and 17 mm year respectively using erosion pins

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

quantitative study of piping processes in badland areas of the ebro basin ne spain abstract in the ebro basin piping is an ubiquitous erosion process in badland areas occurring in two main situations on slopes of exposed tertiary clays and in recently incised silty clay holocene valley fill sediments the quantitative importance of the main factors controlling piping processes in those conditions was obtained by statistical analysis based on multiple and stepwise regressions piping erosion is strongly related to a high sodium absorption ratio sar which favours clay dispersion however the statistical analysis indicates that the chemical characteristics and the physical chemical behaviour are a necessary condition but are not sufficient on their own to develop piping processes on the slopes piping is controlled by the physical and chemical properties of the material such as the dispersion index the granulometric fraction smaller than 4 m ph and crack density in the valley fill sediments piping is mainly controlled by the sulphate concentration in the water extract from saturated paste which is also associated with high sar values and the dispersion index in both geomorphic situations piping is always related to high crack density and high topographic gradient

variations of sea surface temperature wind stress and rainfall over the tropical atlantic and south america abstract empirical orthogonal functions e0fs and composite analyses are used to investigate the development of sea surface temperature sst anomaly patterns over the tropical atlantic the evolution of large scale rainfall anomaly patterns over the equatorial atlantic and south america are also investigated the eof analyses revealed that a pattern of anomalous sst and wind stress asymmetric relative to the equator is the dominant mode of interannual and longer variability over the tropical atlantic the most important findings of this study are as follows atmospheric circulation anomalies precede the development of basinwide anomalous sst patterns over the tropical atlantic anomalous sst originate off the african coast simultaneously with atmospheric circulation anomalies and expand westward afterward the time lag between wind stress relaxation strengthening and maximum sst warming cooling is about two months anomalous atmospheric circulation patterns over northern tropical atlantic are phase

patterns of topographic change in sub humid badlands determined by high resolution multi temporal topographic surveys abstract badlands are highly erodible landscapes with sparse vegetation and rapid runoff responses badland surfaces experience high erosion rates that may have a direct and marked influence on river channel networks and catchment scale sediment budgets erosion rates from badlands have been widely estimated by discrete observations of topographic change measured by erosion pins or profile meters recent developments in survey instrumentation provide the opportunity to build high resolution topographic models over multiple spatial scales at sub centimeter accuracy in this paper we demonstrate how reliable estimates of topographic variables and temporal change can be derived for badlands by repeat terrestrial laser scanning tls surveys undertaken at multiple temporal event to annual scales a total of seven tls surveys were obtained in an experimental sub humid badland located in the central pyrenees data analyses were conducted on two temporal scales a five rainfall events and b three long term spaced over an annual cycle scales our results show a clear erosional pattern for most of the badland at the annual scale i e annual net change at around 6 cm yr 1 aspect surface roughness and slope were significant predictors of topographic change although the sign and magnitude of the change differed at the event scale net topographic change at the event scale varied from 1 8 to 1 4 cm although these patterns could be also affected by swell shrink processes surface roughness was more important at controlling badland geomorphological processes at the event scale than the annual scale our observations suggest that longer term studies may underestimate the importance of surface roughness as a control on badland geomorphology at the annual scale the effect of aspect in the sign of the topographic change was removed and slope becomes more important erosion proved to be dominant on slopes higher than 100 overall the results indicate that coupling of appropriately scaled spatial and temporal data is critical to understand topographic changes and their drivers on badlands although the approach outlined in this paper was only applied to a relatively small area with careful survey design and application of new survey technology it could readily be upscaled to cover entire badland systems such surveys would permit detailed analysis of controls of sedimentological connectivity across badlands and their influence on channel networks and catchment sediment budgets

geomorphic agents versus vegetation spreading as causes of badland occurrence in a mediterranean subhumid mountainous area abstract previous evidence on the chief role of physical weathering on badland development in the vallcebre area south eastern pyrenees led to the study of the amounts of energy available for the main geomorphic agents and to analyze the results in the light of the patterns of vegetation cover and species distribution in order to explain both the occurrence of these badland forms and their preference for north facing shady hillslopes results showed that the weathering potential provided by freezing is about two orders of magnitude greater than rainfall kinetic energy and that the former strongly depends on hillslope aspect the study of vegetation demonstrated that vegetation is poorer in cover and species composition on shady hillslopes than on sunny ones spontaneous revegetation of these surfaces being restrained by cold thermal conditions rather than by water availability these results show that the occurrence of these badland areas depends on montane climatic attributes that control geomorphic and biological processes and that are different from those that promote the occurrence of badlands in dry mediterranean areas the preference for northern aspects provides evidence for these differences

high resolution topography for understanding earth surface processes opportunities and challenges abstract in the last decade a range of new remote sensing techniques has led to a dramatic increase in terrain information providing new opportunities for a better understanding of earth surface processes based on geomorphic signatures technologies such as airborne and terrestrial lidar light detection and ranging to obtain high resolution topography have opened avenues for the analysis of landslides hillslope and channellization processes river morphology active tectonics volcanic landforms and anthropogenic signatures on topography this review provides an overview of the recent flourishing literature on high resolution topographic analyses underlining their opportunities and critical issues such as their limitations the goal is to provide answers to questions such as what kind of processes can be analyzed through high resolution topographic data and how to do it the review focuses on two different environments natural and engineered landscapes in both contexts high resolution topography offers opportunities to better understand geomorphic processes from topographic signatures particular attention is given to engineered landscapes in which the direct anthropic alteration of processes is significant the last part of the review discusses future challenges

morphology and development of selected badlands in southeast spain implications of climatic change four areas were selected to represent a range of processes characteristic of badland surfaces in southeast spain petrer and monnegre in alicante vera and tabernas in almeria at petrer rilling and swelling processes produce a deeply cracked surface drained by a finely textured network of shallow rills at monnegre piping and rilling are differentially developed on slopes ultimately controlled by basal incision at vera aspect controlled lichen and vegetation cover produce a sequence of badland development within which the relative importance of piping mass movement and rilling varies through the sequence at tabernas simple overland flow is the dominant process but aspect influences rill network density and badland evolution the factors controlling badland development can be grouped into those related to gross morphology to surface cover and runoff generation and to material properties these factors are effective over varying timescales implying that morphological response times differ among the selected badlands

tropical atlantic sea surface temperature variability and its relation to el nino southern oscillation past analyses of tropical atlantic sea surface temperature variability have suggested a dipole behavior between the northern and southern tropics across the intertropical convergence zone itcz by analyzing an improved 43 year 1950 1992 record of sst smith et al 1996 and other data derived from the comprehensive ocean atmosphere data set coads it is shown that the regions north and south of the itcz are statistically independent of each other at the seasonal to interannual timescales dominating the data confirming the conclusions of houghton and tourre 1992 some dipole behavior does develop weakly during the boreal spring season when there is a tendency for sst anomaly west of angola to be opposite of that in the tropical north atlantic it is further shown that tropical atlantic sst variability is corre lated with pacific e1 nifio southern oscillation enso variability in several regions the ma jor region affected is the north atlantic area of ne trades west of 40ow along 10on 20on and extending into the caribbean there about 50 80 of the anomalous sst variability is associ ated with the pacific enso with atlantic warmings occurring 4 5 months after the mature phases of pacific warm events an analysis of local surface flux fields derived from coads data shows that the enso related atlantic warmings occur as a result of reductions in the surface ne trade wind speeds which in turn reduce latent and sensible heat losses over the region in ques tion as well as cooling due to entrainment this enso connection is best developed during the boreal spring following the most frequent season of maximum enso anomalies in the pacific a region of secondary covariability with enso occurs along the northern edge of the mean itcz position and appears to be associated with northward migrations of the itcz when the north at lantic warmings occur although easterly winds are intensified in the western equatorial atlantic in response to pacific warm events they do not produce strong local changes in sst contrary to expectations from studies based on equatorial dynamics these teleconnected wind anomalies do not give rise to significant correlations of sst in the gulf of guinea with the pacific enso as the teleconnection sequence matures strong se trades at low southern latitudes follow the de velopment of the north atlantic sst anomaly and precede by several months the appearance of weak negative sst anomalies off angola and stronger positive anomalies extending eastward from southern brazil along 15o 30os

the sediment budget of a highly dynamic mesoscale catchment the river isabena the paper presents the sediment budget of the isabena basin a highly dynamic 445 km2 catchment located in the central pyrenees that is patched by highly erodible areas i e badlands the budget for the period 2007 2009 is constructed following a methodology that allows the interpolation of intermittent measurements of suspended sediment concentrations and enables a subsequent calculation of sediment loads data allow specification of the contribution of each subbasin to the water and sediment yield in the catchment outlet mean annual sediment load was 235 000 t y 1 specific sediment yield reached 2000 t km 2 y 1 a value that indicates very high sedimentary activity especially in the case of villacarli and lascuarre subcatchments were most badlands are located the specific sediment yield obtained for the entire isabena is 527 t km 2 y 1 a high value for such a mesoscale basin results show that a small part of the area i e 1 controls most of the catchment s gross sediment contribution sediment delivery ratio ratio between sediment input from primary sources and basin export has been estimated at around 90 while in channel storage represents the 5 of the annual load on average the high connectivity between sediment sources i e badlands and transfer paths i e streamcourses exacerbates the influence of the local sediment production on the catchment s sediment yield a quite unusual fact for a basin of this scale

causes of the el nino and la nina amplitude asymmetry in the equatorial eastern pacific abstract the amplitude asymmetry between el nino and la nina is investigated by diagnosing the mixed layer heat budget during the enso developing phase by using the three ocean assimilation products simple ocean data assimilation soda 2 0 2 soda 1 4 2 and the global ocean data assimilation system godas it is found that the nonlinear zonal and meridional ocean temperature advections are essential to cause the asymmetry in the far eastern pacific whereas the vertical nonlinear advection has the opposite effect the zonal current anomaly is dominated by the geostrophic current in association with the thermocline depth variation the meridional current anomaly is primarily attributed to the ekman current driven by wind stress forcing the resulting induced anomalous horizontal currents lead to warm nonlinear advection during both el nino and la nina episodes and thus strengthen weaken the el nino la nina amplitude the convergence divergence of the anomalous geostrophic mixed layer currents dur

clay mineralogy as a crucial factor in badland hillslope processes abstract comprehensive and important work has been done in understanding badland processes on both the big scale and more recently on smaller scale in order to understand the subtle differences between sites however most studies lack important information regarding clay mineralogy and their importance for weathering processes type and rate of weathering depend on material physico chemical properties climatic regimes and slope characteristics as weathering progresses the surface conditions change influencing erosion processes usually badland lithologies are reported as sodium rich highly dispersive materials but that is not invariably true the primary objective of this study is to show that clay minerals have an important role in defining surface and subsurface processes on badland hillslopes field studies conducted in dinosaur park badlands alberta canada chinguacousy badlands ontario canada and sestino badlands tuscany italy have shown that there are two dominant clay rich lithologies smectite rich and smectite poor mudrocks different surface crust and weathering profiles were observed on smectite rich mudrocks during two field years with distinct precipitation inputs after a dry fall winter season the popcorn surface was very well developed 2 3 cm the subsurface layer 10 15 cm thick overlaid the layer of smaller shards followed by the unweathered material after a very wet fall winter season the surface layer was denser and thinner 0 5 cm with wider cracks and a thin subsurface layer attached to the crust weathering profiles on smectite poor lithologies did not show any differences with variable climatic conditions a thin surface layer was composed of soft thin and small 0 5 0 3 0 1 cm shards a layer of larger shards overlying unweathered material was beneath it in order to better understand the described occurrences badland materials were monitored in controlled laboratory conditions during an incremental weathering experiment six samples of each material were subjected to 10 cycles of simulated rainfall which duration ranged 10 60 min very short rainfalls 10 20 min can cause swelling of clay minerals in smectite rich materials and formation of popcorn surface during drying periods during subsequent wetting drying periods the crust becomes flatter and denser and desiccation cracks become wider and deeper samples subjected to 50 and 60 min of rainfall showed maximum swelling after only one cycle of rainfall after this swift swelling samples became unstable and dispersive during subsequent wetting dispersion became dominant resulting in flatter surfaces thinner crust and narrower desiccation cracks smectite poor mudrocks appeared to be resistant to variable wetting and drying large shards broke down into smaller due to differential swelling of illite and chlorite once they were reduced to tiny flaky shards the surface became compacted the surface cracks served as the initial pathways for sediment and water movement knowing if the material is smectite rich or smectite poor can help in prediction of processes and the erosion rates the amount intensity and duration of precipitation will determine not only the rate of weathering but also the type of the weathered surface on smectite rich surfaces smectite poor materials appear to be more resistant to change in precipitation

filtering spatial error from dems implications for morphological change estimation abstract scour and fill estimation from digital elevation model dem subtraction or differencing is an increasingly common technique in morphological and sediment transport investigations the technique is commonly used to estimate scour and fill volumes and to produce scour and fill maps that provide process based information to geomorphologists accounting for sources of uncertainty within the dem is of critical importance dem error is spatially variable and has a tendency to be greater at breaks of slope such as bar and bank edges in the past however this has been achieved using a uniform error metric across the dem resulting in over conservative estimates of error in turn this has led to over conservative scour and fill volumes and incorrect process interpretation this paper applies a new approach that permits assessment of spatially distributed error across a dem the method is tested on a sequence of field surveys of the gravel bed river nent cumbria uk the results demonstrate some dramatic differences application of conventional techniques that account for mean error across a dem led to a 15 and 31 underestimation in scour and fill volumes respectively between july and october 1998 whilst for the october 1998 june 1999 subtraction 31 and 13 of scour and fill were underestimated respectively use of a uniform error across a surface captures less change in comparison to a spatially distributed approach furthermore the changes captured using a uniform error are biased toward areas of the channel that have more local topographic variability such as bar and bank edges in contrast the use of a spatially distributed approach provides information on change from flatter surfaces such as bar tops that would otherwise be missed this study also demonstrates that estimates of morphological change can be misleading in the absence of an error filter where the raw survey data is available it is recommended that sediment budgeting studies take account of the spatial variability of error in each dem involved in the subtraction

lithology controls the regional distribution and morphological diversity of montane mediterranean badlands in the upper llobregat basin eastern pyrenees abstract badlands are pervasive in a wide range of environmental conditions across the mediterranean region including arid semiarid and humid environments on montane cold subhumid and humid mediterranean landscapes harsh thermal conditions on north facing hillslopes favour intense bedrock weathering by freezing and impose serious constraints on plant colonization the above are the customary arguments to explain the high abundance of montane badlands on north exposed shady aspects we studied the distribution and morphological diversity of badlands in the upper llobregat basin catalan pyrenees ne spain using remote sensing information high resolution orthophotos and complementary landsat 8 imagery digital elevation data and regional information on lithology badlands extend over about 200 ha in the upper llobregat basin and occur on two different parent materials swelling smectite rich continental garumnian lutites of late cretaceous age and nonswelling illitic marine eocene marls vegetation assessed by remote sensed vegetation greenness is less developed on north facing badland slopes however badland slope aspect distribution varies considerably with lithology while badlands on eocene marls show preferential distribution on north facing shady slopes badland occurrence on garumnian lutites does not reveal clear slope aspect anisotropy patterns lithology also affects slope gradient with badlands on eocene marls showing rougher topography 30 40 average slope angle than on garumnian lutites 20 30 badland morphological differences induced by lithology are discussed in terms of the greater weathering susceptibility and slope instability of the swelling smectite rich garumnian lutites than of the nonswelling eocene marls elevation which broadly controls annual precipitation and winter air temperature within the region shows no clear influence on badland distribution overall our results reveal lithology as the main factor controlling badland distribution and morphological diversity under the montane mediterranean conditions of the upper llobregat basin

morphodynamics of a gully and floodout system in the sneeuberg mountains of the semi arid karoo south africa implications for local landscape connectivity abstract the aim of this study was to investigate sedimentary processes in a discontinuous gully system and to establish how they impacted upon overland flow and erosion in the short term while also considering their impact on long term landscape connectivity this manuscript documents the effect that a series of discontinuous gullies located in the semi arid karoo south africa had on local valley morphology and landscape evolution the longitudinal and cross sectional morphology of two discontinuous gully systems were accurately surveyed in addition the sedimentology of eight cores was described and sediment particle size and percentage organics determined while the activity of the radioactive element 210 pb was measured in three of the cores in contrast to previous studies floodouts on the karoo gullies formed progressively downstream as avulsion occurred on the floodout more quickly than upstream backfilling 210 pb geochronology suggests that the most recent avulsion occurred following one of the wettest seasons on record where double the mean annual rainfall fell in just a few months a series of palaeo floodouts along the length of the gullies suggests that the process of gullying and depositional floodout formation is not restricted to the recent past and is a long term landscape process thus despite the lack of characteristic cut and fill features such as terraces the long term evolution of the karoo landscape may be related to episodic gullying in the short term palaeo and current floodouts alter the overland flow hydrology of the landscape and prevent the local formation of badlands by diverting overland flow away from gully thalwegs this results in the formation of amphitheatre type gullies with laterally eroded areas draining into narrow outlet channels incised into palaeo floodouts

three decades of monitoring in the rio cordon instrumented basin sediment budget and temporal trend of sediment yield this paper investigates nearly 30 years of monitoring of sediment fluxes in an instrumented alpine basin rio cordon italy the collected bedload and suspended sediment transport data allows sediment dynamics to be analyzed at different time scales ranging from short single event to long term three decades the rio cordon monitoring station has been operating since 1986 continuously recording water discharge bedload and suspended load at the flood event scale a good relationship was found between peak discharges qpeak and sediment load bedload and suspended load the inter annual sediment yields were analyzed also assessing the contribution of the single floods to the total sediment budget the annual suspended load ranges from 10 to 2524 t yr 1 while the bedload varies from 0 to 1543 t yr 1 the higher annual yields were recorded in the years when large floods occurred highlighting that the sediment budget in the rio cordon is strongly controlled by the occurrence of high magnitude events investigation of the seasonal suspended load contribution demonstrated that from 1986 to 1993 most fine sediments were transported during the snowmelt summer seasons while autumn and snowmelt were the dominant seasons contributing to sediment yield in the periods 1994 2002 and 2003 2014 respectively the mean annual sediment yield from 1986 to 2014 is equal to 103 t km 2 yr 1 and overall bedload accounts for 21 of the total sediment yield the ratio between the sediment transport and the effective runoff of the events allowed the temporal trends of transport efficiency to be inferred highlighting the existence of periods characterized by different sediment availability in particular despite no significant changes in the hydrological variables i e rainfall nearly a decade 1994 2002 with high transport efficiency appears to have occurred after an exceptional event recurrence interval 100 years this event affected the sediment availability at the basin and channel bed scales and provided a legacy influencing the sediment dynamics in the basin over the long term by increasing the transport efficiency for approximately a decade this work benefits from the long lasting monitoring program undertaken in the rio cordon and is the product of long term data series the quasi unique dataset has provided detailed evidence of sediment dynamics over about three decades in a small alpine basin also enabling the effects triggered by an exceptional event to be analyzed

from experimental plots to experimental landscapes topography erosion and deposition in sub humid badlands from structure from motion photogrammetry in the last decade advances in surveying technology have opened up the possibility of representing topography and monitoring surface changes over experimental plots 10 m2 in high resolution 103 points m 1 yet the representativeness of these small plots is limited with structure from motion sfm and multi view stereo mvs techniques now becoming part of the geomorphologist s toolkit there is potential to expand further the scale at which we characterise topography and monitor geomorphic change morphometrically moving beyond previous plot scale work using terrestrial laser scanning tls surveys this paper validates robustly a number of sfm mvs surveys against total station and extensive tls data at three nested scales plots 30 m2 within a small catchment 4710 m2 within an eroding marl badland landscape 1 km2 sfm surveys from a number of platforms are evaluated based on i topography ii sub grid roughness and iii change detection capabilities at an annual scale oblique ground based images can provide a high quality surface equivalent to tls at the plot scale but become unreliable over larger areas of complex terrain degradation of surface quality with range is observed clearly for sfm models derived from aerial imagery recently modelled doming effects from the use of vertical imagery are proven empirically as a piloted gyrocopter survey at 50m altitude with convergent off nadir imagery provided higher quality data than an unmanned aerial vehicle uav flying at the same height and collecting vertical imagery for soil erosion monitoring sfm can provide data comparable with tls only from small survey ranges 5 m and is best limited to survey ranges 10 20 m synthesis of these results with existing validation studies shows a clear degradation of root mean squared error rmse with survey range with a median ratio between rmse and survey range of 1 639 and highlights the effect of the validation method e g point cloud or raster based on the estimated quality

regolith behaviour and physical weathering of clayey mudrock as dependent on seasonal weather conditions in a badland area at vallcebre eastern pyrenees abstract studies on badland areas in the vallcebre basin pyrenees suggest that erosion rates are controlled by the weathering rate of mudrocks to obtain the temporal pattern of physical weathering and its control on the erosive processes monitoring of regolith temperatures at different aspect depth and lithology and periodical determination of regolith moisture and bulk density were carried out changes in surface regolith have also been monitored by means of photographic techniques using an especially designed tripod finally the hydrological and erosive response of the regolith trough the seasons were studied using rainfall simulations the results obtained support and confirm previous knowledge on the role of frost action in mudrock weathering and the role of subsequent regolith development and wetness status on infiltration and runoff generation these seasonal changes of behaviour are so important that they raise serious questions about the validity of observations or experiments carried out in only one season this work confirms that erosion processes are controlled by regolith formation during winter and regolith depletion by storm rainfall erosion during summer spring and early autumn it also raises important points about annual trends of infiltration and erodibility that should be used as guidelines for modelling runoff and sediment production

field observations experiments and modeling of sediment production from freeze and thaw action on a bare weathered granite slope in a temperate region of japan abstract in the present study field observations and model simulations were conducted to examine the process of sediment production due to freeze and thaw action in a temperate climate region two small areas were designated and observations were conducted to determine the mechanisms of sediment production due to freeze and thaw action on a bare weathered granite slope in the tanakami mountains in the southern part of shiga prefecture japan during the cold season from 2004 to 2005 air surface and subsurface temperatures were measured at 10 min intervals the sediment produced on plot 1 was collected and weighed once per week whereas the sediment produced on plot 2 was left untouched until the end of the cold season the freeze and thaw cycle occurred repeatedly with the frozen zone i e temperature 2 year 1 of sediment respectively this difference indicates that sediment cover of the saprolite surface mitigated the destructive effects of freezing during the cold season from 2005 to 2006 a half of plot 1 was covered by broadleaves quercus serrata and the other half was covered by coniferous leaves pinus densiflora plot 2 was covered by no leaves to understand the effects of surface cover on the reduction in sediment production the results showed that surface leaf cover dramatically decreased sediment production due to freeze and thaw action versus the no surface cover a simulation model combining a thermal conductivity analysis and a simple and empirical sediment production model was developed to estimate the amount of sediment produced by the freeze and thaw action the observation results of temperature change and amount of sediment during the first season from 2004 to 2005 were simulated with the model the model assumption that repeated freezing and thawing events are necessary for the production of sediment from saprolite 14 cycles of the freeze and thaw with a freezing threshold of 1 c is supported by comparisons of the simulated results and the observations from an engineering viewpoint a freeze and thaw index that incorporates the freezing depth and the repetition number of freeze and thaw cycles is proposed to estimate total amount of sediment produced from a wide area such as a catchment scale over a long period

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

connectivity as a crucial determinant of badland morphology and evolution the way in which threshold behaviour landscape sensitivity and connectivity1 operate together at the meso and macro scale in badlands is initially considered from a theoretical energy utilisation perspective the argument is developed that intrinsic changes to process domain dominance can result in progressive shifts in process connectivity without the need to invoke external climatic or tectonic change from this premise a meso scale closed system model for the evolution of connected states in regionally isolated badlands is developed applicable to systems evolving towards a fixed base level within a less erosive host landscape the model shows how badlands disconnected from regional drainage can develop from a wide range of initial states into a convergent quasi equilibrium followed by a period of complex response as energy is dissipated across thresholds giving rise to a range of equifinal maximum entropy landscapes this classification is illustrated using a range of global badland examples longer term macro scale interruptions to this semi deterministic model of badland relief degradation are also considered from this longer term larger scale perspective it is argued that extrinsic changes to relative relief can be driven by base level changes tectonically isostatically or eustatically induced in which case the continuity and linkages of information within the system are modified by effects which move up through the system bottom up control macro scale climatic changes also alter connectivity by changing the power distribution of prevailing events and by causing long term changes in mean precipitation temperature and e p ratio which affect vegetation and therefore runoff resistance all across the landscape from this perspective longer term climatic change operates in a top down manner the interplay between these two larger scale controls will inevitably determine the pattern of connected states that the landscape experiences through time the top down and bottom up combinations that can lead to either rejuvenation and a return to the stages described for the closed system model or stabilisation enhanced phases of both morphological and geochemical stabilisation are discussed

role of erosion processes on the morphogenesis of a semiarid badland area bardenas reales ne spain abstract bardenas reales badlands are located in the middle western sector of the ebro depression northern spain this consists of a big erosional depression with deeply dissected valley bounded by steep slopes labile argillaceous bedrock scarce high intensity rainfall and high temperatures make erosion the dominant morphogenetic process several erosion processes operate in the bardenas reales rilling gullying piping and mass movements the relative role played by these processes on the morphogenesis is largely controlled by physico chemical properties of the materials and climatic conditions precipitation distribution over the year controls the development of mass movements whereas regolith physical chemical properties favor piping gullying and rilling during the rainfall maxima soil erodibility in this area is clearly controlled by the sodium content and the presence of swelling clays these factors determine the distribution and appearance of piping processes cracking in holocene clay deposits devoid of swelling clays is related to high sodium content that confers a dispersive character clay dispersion causes loss of cohesion favoring piping in the rainfall maxima soil loss is significant and controlled by precipitation amount and maximum intensity conversely during periods of cyclonic rain erosion is scarce and mass movements are the dominant process in the slopes underlain by tertiary mudstones mud flows are frequent during the winter months in winter time when rains are of low intensity and evapotranspiration is limited infiltration through cracks is high consequently water content in the regolith may increase until the plastic limit is reached under these conditions and due to the high gradient of the slopes 34 shear strength is surpassed and the clay material is able to slide and flow

geochronology biostratigraphy and changing shell morphology in the land snail subgenus poecilozonites during the quaternary of bermuda shells from over 280 collections representing all known forms of subgenus poecilozonites zonitidae from bermuda have been ranked in stratigraphic order and relative age aminostratigraphy the samples were first grouped by their source lithostratigraphic unit with additional refinements being made based on the epimerization ratio d alloisoleucine l isoleucine or a i from nearly 400 representative individual shells of each of the forms a plot of a i frequency defines several modes or aminozones the aminozones correlate strongly with defined lithostratigraphy with some minor variation resulting from less optimally preserved shells the succession of land snails is ranked over chronological range from the middle and early pleistocene with greatest resolution since 500 ka this 500 ka age range and density of sampling is among the most extensive for any organism on an oceanic island morphological analysis of poecilozonites demonstrates oscillation and repetition of morphotypes over multiple sea level cycles shells from the small island s that formed during interglacial times are generally small and show little variation in form during glacial periods when bermuda reached maximal size shells are much larger extreme variation in shell size and shape occurs at interglacial glacial transitions in as little as 2 4 ka because the subgenus has been endemic to bermuda for at least ca 1000 ka such dramatic and rapid shifts in shell morphology cannot be the result of recolonization from outside sources an intact and undisturbed 130 ka long biostratigraphic record of poecilozonites is contained in a single vertical 2 m thick talus accumulation in admirals cave that has been dated at high resolution by three independent techniques the bio and chronostratigraphy show that snails were very large at the close of glacial stage marine isotope stage mis 6 small during interglacial mis 5 re evolved identical large size during the last glaciation mis 4 2 and changed abruptly to the small paedomorphic modern form at the onset of the holocene mis 2 1 about 10 12 ka ago when assessed with care shells of poecilozonites may be used as guide fossils for rapid field identification of lithostratigraphic units in surface deposits and as chronological indicators in cave and fissure fills when used in combination with vertebrate remains

flood based analysis of high magnitude sediment transport using a non parametric method francke t lopez tarazon j a vericat d bronstert a batalla r j 2008 flood based analysis of high magnitude sediment transport using a non parametric method earth surface processes and landforms 33 13 2064 2077 sponsorship sesam catalan government european social fund

modeling river bed morphology roughness and surface sedimentology using high resolution terrestrial laser scanning 1 recent advances in technology have revolutionized the acquisition of topographic data offering new perspectives on the structure and morphology of the earth s surface these developments have had a profound impact on the practice of river science creating a step change in the dimensionality resolution and precision of fluvial terrain models the emergence of hyperscale survey methods including structure from motion photogrammetry and terrestrial laser scanning tls now presents the opportunity to acquire 3 d point cloud data that capture grain scale detail over reach scale extents translating these data into geomorphologically relevant products is however not straightforward unlike traditional survey methods tls acquires observations rapidly and automatically but unselectively this results in considerable noise associated with backscatter from vegetation and other artifacts moreover the large data volumes are difficult to visualize require very high capacity storage and are not incorporated readily into gis and simulation models in this paper we analyze the geomorphological integrity of multiscale terrain models rendered from a tls survey of the braided river feshie scotland these raster terrain models are generated using a new computationally efficient geospatial toolkit the topographic point cloud analysis toolkit topcat this performs an intelligent decimation of point cloud data into a set of 2 5 d terrain models that retain information on the high frequency subgrid topography as the moments of the locally detrended elevation distribution the results quantify the degree of terrain generalization inherent in conventional fluvial dems and illustrate how subgrid topographic statistics can be used to map the spatial pattern of particle size grain roughness and sedimentary facies at the reach scale