wind control of storm triggered shallow landslides 1 heavy rainstorms are a major control of shallow landsliding in mountainous areas the influence of three dimensional 3 d variability of precipitation is analyzed by coupling a fine resolution atmospheric model rams with a fine resolution topographic model dem to represent the 3 d precipitation flux generating the catastrophic flood that occurred in versilia central italy on 19 june 1996 matching of this flux with the observed scars and debris shows that 92 of the mass movements occurred where the normalized precipitation flux exceeds 0 80 and less then 2 where this is null these results give an insight of the detected role of exposure in explaining the spatial variability of observed landslides as emerging from multivariate statistical analysis the interaction of the wind driven precipitation field with topography is an important control of shallow landslides triggered by convective storms in upland catchments

placer mining along the fraser river british columbia the geomorphic impact we investigate the geomorphic impact of nineteenth century placer mining along the fraser river british columbia by estimating the volume and grain size distribution of excavated sediment evaluating the transport potential for the sediment in the river and discussing the relation between placer waste sediment and observed morphodynamics of the fraser river channel volume by area regression relations applied to 456 mapped mines estimate the total volume of material excavated to be 58 10 6 m 3 bulk volume sampling of mine scarp and mine lag sediments indicates that the discharged tailings consisted of 54 sand and finer material and 46 gravel and small cobbles modern observation and historical narratives indicate that the channel of the fraser between quesnel and laidlaw has been generally stable following placer mining application of a sediment transport function indicates that the river is capable of moving annually an amount of sediment comparable to the maximum loading from placer mining by applying established relations between channel scale and sediment virtual velocity we estimate the rate of downstream movement of the placer waste slug to be between 1 and 6 km yr 1 the predicted rates of sediment migration indicate that peak delivery of placer waste to the lower river below laidlaw likely occurred early in the twentieth century this predicted behavior agrees well with observed aggradation on the lower river the result emphasizes the importance of historical legacy in the appraisal of recent geomorphological processes and shows that widespread small scale disturbance has affected the fraser river with the effect concentrated where the gradient of the river is reduced

sediment from hydraulic mining detained by englebright and small dams in the yuba basin recent initiatives to find ways to reintroduce anadromous fish to the central valley of california have identified the yuba river as one of the best potential watersheds for expanding spawning habitat of spring run chinook salmon and steelhead trout salmon spawning in the yuba river would require substantial modifications or removal of englebright dam a large dam 86 million m 3 capacity built by the u s army corps of engineers in 1941 an extensive on going feasibility study by local state and federal organizations therefore is examining aspects of various dam treatment scenarios that range from no action to complete dam removal this paper examines the extraordinary history of the watershed and resulting conditions pertinent to the feasibility of altering englebright dam it seeks to accomplish four goals first historical geomorphic changes in the watershed are outlined that influence the physical context of the feasibility study the yuba watershed is centered in the hydraulic gold mining region made

tributary trunk stream relations in a cut and fill landscape a case study from wolumla catchment new south wales australia at the time of european settlement of the south coast of new south wales australia in the mid nineteenth century river courses were discontinuous throughout wolumla catchment within a few decades of settlement intact valley fills had been transformed into incised channels along trunk streams this induced associated patterns of secondary incision into tributary valley fills three of the primary subcatchments in wolumla catchment became fully incised while an upland swamp and a floodout i e sand sheet deposits atop an intact valley floor remain in mid catchment of the fourth subcatchment of the 70 lower order tributaries which join the trunk streams in the four subcatchments 27 have incised 12 of which are discontinuously incised incision of tributary streams in wolumla catchment cannot be explained by subcatchment area and slope relations the position of the trunk stream channel within the valley floor trough is the key determinant of whether or not tributary streams have incised changes to river morphology since european settlement have altered the linkage of tributary streams to the trunk stream impacting directly on the within catchment transfer of water and sediment

planetary science a chunk of ancient mars analysis of a meteorite found in northwest africa prosaically named nwa 7533 indicates that it is the first sample of the regolith or soil of mars and is derived from the earliest martian igneous crust yet identified see letter p 513 this paper identifies the nwa 7533 meteorite from northwest africa as the first sample of martian highlands rock in the meteorite collection munir humayun and co authors show that nwa 7533 has a composition indicative of a highlands breccia it also contains zircons more than 4 4 billion years old implying that early crustal differentiation on mars occurred in the first 100 million years of its history coeval with earliest crust formation on the moon and the earth

evaluation of prediction capability of the artificial neural networks for mapping landslide susceptibility in the turbolo river catchment northern calabria italy abstract landslides are one of the most widespread natural hazards that cause damage to both property and life every year and therefore the spatial distribution of the landslide susceptibility is necessary for planning future developmental activities in this paper the artificial neural network ann technique is tested for developing a landslide susceptibility map in turbolo river catchment north calabria south italy landslides were mapped through air photo interpretation and field surveys by identifying both the landslide depletion zones dzs and accumulation zones azs and relevant geo environmental thematic layers pertaining to landslide predisposing factors were generated using air photo interpretation field surveys and geographic information system gis tools ten predisposing factors were related to the occurrence of landslide lithology faults land use drainage network and a series of topographic factors elevation slope aspect plan curvature topographic wetness index twi and stream power index spi in order to evaluate and validate landslide susceptibility the dzs were divided in two groups using a random partition strategy the first group training set was used to prepare the susceptibility map employing a back propagation learning algorithm in the idrisi taiga software the second group testing set was used to validate the landslide susceptibility model using the confusion matrix and the receiver operating characteristic roc curve the susceptibility map was classified into five susceptibility classes very low low moderate high and very high about 46 of the study area falls in high to very high susceptible classes and most of the dzs mapped 87 3 occur in the same classes the validation results showed satisfactory agreement between the susceptibility map and the dzs locations over 85 of the dzs of the validation set are correctly classified falling in high and very high susceptibility areas also the roc curve had shown an area under curve auc value of 0 90 which demonstrates the robustness and good reliability of the landslide susceptibility model according to these results we conclude that the map produced by the artificial neural network is reliable and the methodology applied in the study produced high performance and satisfactory results which may be useful for land planning policy

assessment of landslide occurrences in serra do mar mountain range using kinematic analyses due to its meteorological geological and geomorphological settings brazilian s atlantic coast have suffered severe landslide phenomena particularly along the cost of sao paulo rio de janeiro and santa catarina states studies have shown that these processes are complex and triggered by several factors however within the study area many landslide locations are placed on gneiss migmatitic terrain with pronounced geological discontinuities the objective of this paper is to assess landslide occurrences in serra do mar caraguatatuba sp and investigate by means of kinematic analysis how they correlate with foliation and fractures present on the rocks kinematic analysis is used to investigate which discontinuities are more favorable to landslides occurrence and their relationship with slope directions structural information and kinematic data models are used to evaluate cause effect relationship of landslide processes results show that dip slopes with ne sw direction have greatest potential for the occurrence of planar landslides on the other hand anti dip and cross dip slopes have a greater potential to develop wedge landslides rock weathering and fluid flux along foliation planes can intensify mass movement such effect is also seen in residual soil since they are able to preserve relict structures of the rock this study contributes to a better understanding of how geological structures preserved in tropical residual soils influence shallow landslides

guiding principles for assessing geomorphic river condition application of a framework in the bega catchment south coast new south wales australia abstract based on principles from the ecological literature a semi quantitative framework to assess geomorphic river condition is outlined guiding principles that underlie the framework include the need to compare like with like selection of appropriate natural reference conditions for differing types of river framed in terms of their natural range of variability and measurement of parameters that are relevant for each type of river solid understanding of river character and behaviour along with assessment of capacity for adjustment and appraisal of river evolution including responses to human disturbance are core components of the framework reference conditions are defined for each type of river using ergodic reasoning the procedure for assessing geomorphic river condition has three steps 1 identify the type of river termed river style and its capacity for adjustment within its valley setting 2 assess river evolution as a basis for identifying irreversible geomorphic change and a natural reference condition 3 determine and explain the geomorphic condition of each reach in a catchment application of the procedure is demonstrated for reaches of an alluvial and a confined river style in bega catchment on the south coast of new south wales australia

bed waves at the basin scale implications for river management and restoration an extensive literature about fluvial sediment waves slugs or pulses has emerged in the past 20 years the concept has been useful in many respects but has been applied to diverse phenomena using a variety of definitions moreover inferred linkages between channel bed changes and sediment loads are often not justifiable this paper reviews concepts of large fluvial sediment waves at scales extending to several tens of kilometres it points out constraints on the inferences that can be made about sediment loads based on changes in channel bed elevation at this scale where channel sediment interacts with storage in floodplain and terrace deposits the type area of g k gilbert s initial sediment wave concept is re examined to show that neither wave translation nor dispersion occurred in the simple manner commonly assumed channel aggradation and return to graded conditions provide an alternative theory explaining gilbert s observed bed elevation changes recognizing the evidence and implications of the former passage of a large scale bed wave is essential to the accurate diagnosis of catchment conditions and the adoption of appropriate river restoration goals or methods sediment loads water quality channel morphologic stability and aquatic ecosystems often reflect changes in sediment storage long after the channel bed has returned to grade copyright 2006 john wiley sons ltd

variability in sediment delivery and storage along river courses in bega catchment nsw australia implications for geomorphic river recovery in many catchments in southeastern australia alluvial stores have been the dominant source of sediments mobilised in the period since european settlement in bega catchment on the south coast of new south wales nsw this has been reflected by dramatic changes to river morphology extensive volumes of material have been released and efficiently flushed to the lowland plain with a sediment delivery ratio of almost 70 however only 16 of these alluvial sediments have been flushed through to the estuary as antecedent controls on valley width have resulted in the lowland plain acting as a large sediment sink the changing nature of sediment source transfer and accumulation zones has varied markedly from subcatchment to subcatchment the volume of material supplied to the lowland plain from differing subcatchments is not related to subcatchment area rather the pattern of river types dictates the spatial variability in storage and transfer over 67 of sediment released has been sourced from just 25 of the catchment from subcatchments characterised by large valley fills cut and fill river style that previously stored extensive volumes of material at the base of the escarpment these parts of bega catchment were especially sensitive to disturbance sediment exhaustion from these parts of the catchment and from river courses elsewhere has major implications for the geomorphic recovery potential of rivers constraining what can be realistically achieved in terms of river rehabilitation

application of lidar and discriminant analysis to determine landscape characteristics for different types of slope failures in heavily vegetated steep terrain horseshoe run watershed west virginia abstract a landslide inventory map was created for horseshoe run watershed west virginia using high resolution topographic data obtained from airborne lidar a total of 152 landslides were remotely mapped and classified as planar slides rotational slumps debris flows debris fans debris slides and active slopes based on morphologic characteristics interpreted from lidar derived shaded relief maps with field verification at several locations seven landscape variables were calculated for the watershed from the high resolution 0 5 m topographic data elevation slope angle slope aspect distance from roads distance from streams plan curvature and profile curvature statistical analyses were conducted to determine the mean and standard deviations for each variable and corresponding slope failure type discriminant analyses were conducted on the different types of failed slopes with a maximum 86 accuracy level to determine which landscape characteristics contribute to each type of landslide results from the discriminant analyses indicate that statistically significant differences exist between the failure classes mapped within the watershed and that slope angle slope aspect and landscape curvature are important variables influencing the type of process the results from this study have important implications for predicting where certain types of slope failures may occur based on landscape characteristics

morphological controls on the downstream passage of a sediment wave in a gravel bed stream sediment waves in river systems have been widely reported although few studies have examined the interaction between these waves and the morphology of the reaches through which they pass this interaction determines how waves are modified as they propagate downstream this study documents the origin and downstream passage of an avulsion generated sediment wave through a 374 m study reach of the allt dubhaig scotland a nested survey framework was adopted with volumes calculated from cross sections spaced between 10 and 40 m apart documenting the origin and downstream passage of the wave the wave moved through an intensively c 1 m cross section spacing monitored 120 m stretch reach a within the study reach allowing assessment of sediment exchanges between the incoming wave and the local morphology successive surveys show the movement of the wave through and out of the reach and also that areas where wave sediment was deposited did not always correspond with areas of subsequent erosion reach a was divided into three morphologically distinct sub reaches 1a 2a and 3a within which sediment fluxes and the three dimensional distribution of erosion deposition were estimated sediment wave input into 1a and 2a relatively stable sub reaches caused forced bar aggradation and erosion of sediment from elsewhere within the reach which then became part of the wave the downstream transfer of this sediment into unstable 3a caused aggradation and in response widespread erosion which increased the magnitude of the sediment wave as it exited reach a sediment exchange between the recipient reach and the wave depends upon local morphological stability and is a crucial process affecting wave magnitude and attenuation the macroscale sediment wave interacted with rather than overwhelmed the recipient morphology 1998 john wiley sons ltd

active channel width as a proxy of sediment supply from mining sites in new caledonia although the channel morphology of upland fluvial systems is known to be strongly controlled by sediment supply from hillslopes it is still difficult to isolate this effect from the other controlling factors of channel forms such as the sediment transport capacity depending notably on the size of the catchment and local conditions e g confinement riparian vegetation valley floor slope the rivers in new caledonia offer an interesting field laboratory to isolate the morphological effect of contrasted sediment supply conditions some of these rivers are known to be highly impacted by the coarse sediment waves induced by the mining of nickel deposits that started in the early 1870s which was particularly intensive between the 1940s and 1970s the propagation of the sediment pulses from the mining sites can be traced by the presence of wide and aggraded active channels along the stream network of nickel rich peridotite massifs a first set of 63 undisturbed catchments in peridotite massifs distributed across the grande terre was used to fit a classic scaling law between active channel width and drainage area a second set of 86 impacted sites where the presence of sediment waves was clearly attested by recent aerial imagery showed systematically wider active channels with a width ratio around 5 established from the intercept ratio of width area power laws more importantly this second set of disturbed sites confirmed that the residual of active channel widths computed from the scaling law of undisturbed sites is statistically positively related to the catchment scale relative area of major mining sediment sources it is therefore confirmed that the characterization of sediment supply conditions is crucial for the understanding of spatial patterns of active channel width and this should be more thoroughly considered in morphological studies of rivers draining environments with contrasted geomorphic activities on hillslopes

one dimensional bed wave movement in lowland rivers we show that recent measurements in the east fork river wyoming of annual gravel wave translation annual bedload transport and annual variations in riverbed cross sectional area can be described to within a factor of 2 by using the gradowczyk characteristic velocity for bed waves to describe gravel wave translation the engelund hansen formula for bedload transport and a duboys like formula for changes in cross sectional area no free parameters are needed

channel response to an extreme flood and sediment pulse in a mixed bedrock and gravel bed river we exploit a natural experiment caused by an extreme flood 500 year recurrence interval and sediment pulse derived from more than 2500 concurrent landslides to explore the influence of valley scale geomorphic controls on sediment slug evolution and the impact of sediment pulse passage and slug deposition and dispersion on channel stability and channel form sediment slug movement is a crucial process that shapes gravel bed rivers and alluvial valleys and is an important mechanism of downstream bed material transport further increased bed material transport rates during slug deposition can trigger channel responses including increases in lateral mobility channel width and alluvial bar dominance pre and post flood lidar and aerial photographs bracketing the 2007 flood on the chehalis river in south western washington state usa document the channel response with high spatial and temporal definition the sediment slug behaved as a gilbert wave with both channel aggradation and sequestration of large volumes of material in floodplains of headwaters reaches and reaches where confined valleys enter into broad alluvial valleys differences between the valley form of two separate sub basins impacted by the pulse highlight the important role channel and channel floodplain connectivity play in governing downstream movement of sediment slug material finally channel response to the extreme flood and sediment pulse illustrate the connection between bed material transport and channel form specifically the channel widened lateral channel mobility increased and the proportion of the active channel covered by bars increased in all reaches in the study area the response scaled tightly with the relative amount of bed material sediment transport through individual reaches indicating that the amount of morphological change caused by the flood was conditioned by the simultaneous introduction of a sediment pulse to the channel network copyright 2015 john wiley sons ltd

coarse sediment connectivity in river channel systems a conceptual framework and methodology identification of coarse sediment connectivity down river channel systems is important for understanding the linkages between river reaches the influence of sediment sources on channel morphology and the mechanisms and liability to propagation of morphological change a conceptual framework is developed in which several types and degrees of connectivity are proposed it is hypothesised that sediment connectivity varies with sediment sources and with stream competence to transport the coarse fractions a method of identifying the status of reaches is developed based on field mapping of morphology and sedimentology the analysis is exemplified by two channels one an ephemeral channel in se spain the other a perennial channel in nw england questions arise over whether reaches that lack channel stores transfer coarse sediment three scenarios are suggested 1 lack of flux due to lack of competence of the reach 2 flushing through of sediment due to high competence and 3 potential transport of coarse sediment but exhaustion or lack of availability changes in connectivity will take place over different time scales depending on the nature of exchange and time scales of storage short term variations in connectivity can be identified by repeated mapping

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

magnitude frequency characteristics and preparatory factors for spatial debris slide distribution in the northern faroe islands abstract the faroe islands in the north atlantic ocean are highly susceptible to debris avalanches and debris flows originating from debris slide activity in shallow colluvial soils to provide data for hazard and risk assessment of debris avalanches and debris flows this study aims at quantifying the magnitude and frequency of their debris slide origins as well as identifying which preparatory factors are responsible for the spatial debris slide distribution in the landscape for that purpose a debris slide inventory was generated from aerial photo interpretation api fieldwork and anecdotal sources covering a 159 km2 study area in the northern faroe islands a magnitude cumulative frequency mcf curve was derived to predict magnitude dependant debris slide frequencies while preparatory factors responsible for spatial debris slide distribution were quantified through gis supported discriminant function analysis dfa nine factors containing geological lithology dip geomorphological slope angle altitude aspect plan and profile curvature and land use infield outfield sheep density information were included in the multivariate analysis debris slides larger than 100 m2 with magnitude expressed as topographic scar area can be predicted from the power law function y 936 26x 1 277 r2 0 98 while a physical explanation is preferred for the roll over pattern of smaller slope failures the dfa is able to correctly classify app 70 of the modeled terrain units into their pre determined stable unstable groups preparatory factors responsible for the spatial debris slide distribution are aspect slope angle sheep density plan curvature and altitude while influence of the remaining factors is negligible

stratigraphic evidence for a pluvial phase between ca 8200 7100 ka from renella cave central italy a stratigraphic and chronological study of the upper level of renella cave apuan alps central italy reveals that two episodes of flowstone accumulation bracket a thick clastic layer deposited between ca 8 2 and 7 1 ka this layer which represents a period of enhanced cave flooding is substantially in phase with an interval of depleted oxygen isotope values previously recorded in a stalagmite from nearby corchia cave interpreted to have resulted from an increase in local precipitation these data confirm that during this period of time the region experienced relatively wetter conditions including an increase in high magnitude events capable of invading the higher passages of renella cave the timing of the clastic phase occurred when the eastern mediterranean experienced deposition of sapropel layer s1 which is thought to reflect the stagnation of sea water produced largely by enhanced flood activity along the nile in response to increased monsoon intensity in northern equatorial africa recent estimates suggest that s1 may have lasted from ca 10 8 to ca 6 1 ka cal bp combined evidence from renella and corchia cave indicates that the period corresponding to the wettest phase in the apuan alps was much shorter than this and suggests that there is no straightforward connection between increased advection of water vapour from the atlantic between 8 2 and 7 1 ka as recorded in the corchia and renella records and monsoon driven enhancement of nile discharge and s1 deposition in the eastern mediterranean

a process based model for colluvial soil depth and shallow landsliding using digital elevation data a model is proposed for predicting the spatial variation in colluvial soil depth the results of which are used in a separate model to examine the effects of root strength and vertically varying saturated conductivity on slope stability the soil depth model solves for the mass balance between soil production from underlying bedrock and the divergence of diffusive soil transport this model is applied using high resolution digital elevation data of a well studied site in northern california and the evolving soil depth is solved using a finite difference model under varying initial conditions the field data support an exponential decline of soil production with increasing soil depth and a diffusivity of about 50 cm 2 yr the predicted pattern of thick and thin colluvium corresponds well with field observations soil thickness on ridges rapidly obtain an equilibrium depth which suggests that detailed field observations relating soil depth to local topographic curvature could further test this model bedrock emerges where the curvature causes divergent transport to exceed the soil production rate hence the spatial pattern of bedrock outcrops places constraints on the production law the infinite slope stability model uses the predicted soil depth to estimate the effects of root cohesion and vertically varying saturated conductivity low cohesion soils overlying low conductivity bedrock are shown to be least stable the model may be most useful in analyses of slope instability associated with vegetation changes from either land use or climate change although practical applications may be limited by the need to assign values to several spatially varying parameters although both the soil depth and slope stability models offer local mechanistic predictions that can be applied to large areas representation of the finest scale valleys in the digital terrain model significantly influences local model predictions this argues for preserving fine scale topographic detail and using relatively fine grid sizes even in analyses of large catchments

reaction and relaxation in a coarse grained fluvial system following catchment wide disturbance abstract the waiapu river catchment drainage area of 1734 km2 is one of the most prolific conveyors of sediment in the world annually delivering roughly 35 mt of fine material to the ocean from eroding gullies hillslopes and reworked sediment on valley floors tectonic and geologic influences in combination with a dynamic climate influenced by tropical cyclones and clearance of vegetation from steep hillslopes predisposes this region to high rates of erosion the bedload sediment regime of the river is strongly influenced by several exceptionally large gullies and gully complexes that produce a coarse grained poorly sorted sediment mixture rapid abrasion and breakdown leads to high rates of suspended sediment yield a wave of bedload material manifesting as elevated bed levels and significant widening of active alluvial fills has been triggered by large inputs of hillslope material from a few key tributary catchments following cyclone bola in 1988 we review the evidence for the relaxation process of the sedimentary system in the subsequent 29 years appraising some of the legacy effects that may endure as associated with reworking of the considerable alluvial stores within the waiapu system we use structure from motion sfm techniques and archival aerial photos to quantify changes in sediment storage at the base of two major gully systems in recent decades a record of over 850 cross section surveys at 62 sites on 10 rivers throughout the catchment 1958 2017 indicates recent transition from a trend of continuous accumulation to downcutting and remobilisation of valley bottom deposits the channel cross sections provide a minimum estimate of sediment flux from source areas to the lower reaches of the river giving a rudimentary but spatially extensive picture of the wave of material cascading through the drainage network the largest impacts occur in the upper steepland rivers closest to the landslide derived sediment supply transport rates here as inferred from cross section change are at a maximum during an aggradational phase following cyclone bola then taper off despite the large sediment accumulations remaining in the system as of 2017 the river is in the process of incising the upper extents of this deposit on a trajectory of recovery toward pre bola conditions the compilation of cross section data provides us with new insights into the sensitivity of particular sites in the landscape as well as the changing relationship between reach sediment storage and transport rates during the response and relaxation phase of a major disturbance in a large catchment

a physically based model for the topographic control on shallow landsliding a model for the topographic influence on shallow landslide initiation is developed by coupling digital terrain data with near surface through flow and slope stability models the hydrologic model topog o loughlin 1986 predicts the degree of soil saturation in response to a steady state rainfall for topographic elements defined by the intersection of contours and flow tube boundaries the slope stability component uses this relative soil saturation to analyze the stability of each topographic element for the case of cohesionless soils of spatially constant thickness and saturated conductivity the steady state rainfall predicted to cause instability in each topographic element provides a measure of the relative potential for shallow landsliding the spatial distribution of critical rainfall values is compared with landslide locations mapped from aerial photographs and in the field for three study basins where high resolution digital elevation data are available tennessee valley in marin county california mettman ridge in the oregon coast range and split creek on the olympic peninsula washington model predictions in each of these areas are consistent with spatial patterns of observed landslide scars although hydrologic complexities not accounted for in the model e g spatial variability of soil properties and bedrock flow control specific sites and timing of debris flow initiation within areas of similar topographic control

the sediment delivery problem abstract the linking of on site rates of erosion and soil loss within a drainage basin to the sediment yield at the basin outlet and improved knowledge and representation of the associated processes of sediment delivery represent a major research need within the field of erosion and sedimentation and also an important scale problem in drainage basin studies this paper reviews the limitations of the sediment delivery ratio concept by considering the problems of temporal and spatial lumping and its blackbox nature some recent advances in our understanding of the sediment delivery system and its modelling are described and the lack of detailed empirical investigations is highlighted the significance of recent concern for the role of sediments in the transport of nutrients and contaminants to sediment delivery studies is introduced and the need for further work in this field is emphasised

impacts of pre vs postcolonial land use on floodplain sedimentation in temperate north america abstract this paper evaluates the relative importance of anthropogeomorphic sedimentation on floodplains in the mid latitudes of north america before and after the arrival of euroamericans geohistorical and geoarchaeological theories have emerged that have conflicts concerning the relative effectiveness of pre and postcolonial anthropogeomorphic change in north america many geoarchaeologists paleoecologists historians and cultural geographers have concluded that intensive precolonial land use resulted in substantially humanized landscapes prior to the arrival of colonists this presents a geomorphic paradox to fluvial geomorphologists and river restorationists who interpret buried floodplain soils as evidence of landscape stability evidence for these theories is reviewed from a geomorphic perspective while making distinctions between ecological and geomorphic change and recognizing spatial and temporal variability in some locations mid millennial land use generated erosion and floodplain sedimentation subsequent indigenous population declines and reductions in land use intensity may have been followed by precolonial geomorphic stability and pedogenesis an abandoned landscape hypothesis that floodplain soils developed on precolonial anthropogenic alluvium and were subsequently buried should be considered where indigenous populations and land use activities were high variability is also noted in postcolonial floodplain sedimentation many stratigraphic studies show that rates of sedimentation increased greatly after colonization in response to land clearance for agriculture timbering and mining an inventory of studies that document postcolonial floodplain sediment shows strong spatial patterns most studies of postcolonial sedimentation cluster in the eastern usa from the mid atlantic southward and in the mississippi valley from wisconsin to mississippi but many occurrences of mining sediment are scattered throughout the west few of the studies reviewed in the west document anthropogenic floodplain sediment from agriculture or logging although more thorough regional inventories could change that vast areas of temperate north america do not have historical deposits that are well represented in the scientific literature so assumptions that legacy sediment on floodplains is ubiquitous are ill founded spatial and temporal variations in pre and postcolonial floodplain sedimentation are complex and more research is needed to fill in the knowledge gaps

relevance of tectonic and structural parameters in triassic bedrock formations to landslide susceptibility in quaternary hillslope sediments important controlling factors of mass movements are generally soil water and geometric topographic terrain factors such as inclination curvature type and degree and the relative position of unstable slopes and embankments in addition various geologic parameters that have a direct or indirect connection to soil mechanical properties of slide masses are also of importance some studies also emphasise tectonic parameters in the context of susceptibility to mass movements this study considers the relevance of tectonic and structural parameters in bedrock formations for landslides in periglacial hillslope sediments on top of the bedrock the research area is part of the southern solling anticline a saddle structure in the middle bunter sandstone formation in northern hesse and southern lower saxony germany in this geologic formation sandstone siltstone and mudstone are interbedded with impermeable strata uplift of the solling anticline in particular during the quaternary resulted in a partially intensive dissection of the bunter sandstone plateau into separate blocks with disrupted tilted and partially rotated layers the structural conditions have an indirect impact upon landslides in the superposed hillslope sediments water flow along strata and joints above water impermeable strata cause water infiltration and moistening of the periglacial hillslope sediments on top of the bedrock mass movements are frequently linked to sites of outcrop springs and occur after long periods of rainfall a gis based analysis was used to statistically evaluate possible factors controlling landslides factors were weighted and included in an empiric statistical model that allows spatial description of hazard potentials due to mass movements in addition to morphologic parameters the structural parameters of the bedrock are of utmost importance for the occurrence of landslides

the dominance of dispersion in the evolution of bed material waves in gravel bed rivers bed material waves are temporary zones of sediment accumulation created by large sediment inputs recent theoretical experimental and field studies examine factors influencing dispersion and translation of bed material waves in quasi uniform gravel bed channels exchanges of sediment between a channel and its floodplain are neglected within these constraints two factors influence relative rates of dispersion and translation 1 interactions between wave topography flow and bed load transport and 2 particle size differences between wave material and original bed material our results indicate that dispersion dominates the evolution of bed material waves in gravel bed channels significant translation requires a low froude number which is uncharacteristic of gravel bed channels and low wave amplitude which for a large wave can be achieved only after substantial dispersion wave material of small particle size can promote translation but it primarily increases bed load transport rate and thereby accelerates wave evolution copyright 2001 john wiley sons ltd

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

time and the persistence of alluvium river engineering fluvial geomorphology and mining sediment in california abstract river managers need to understand fluvial systems as they change through time many river systems are presently in a state of flux as a result of substantial anthropogenic changes to water and sediment regimes and channel hydraulics yet historical approaches to understanding river systems rarely receive adequate attention because historical methodologies are not conducive to the application of quantitative analysis while there is limited precision in most historical reconstructions the information derived from these studies constrains other interpretations and is essential to a full understanding of the behavior of fluvial systems geomorphology provides a perspective on river systems in which time at various scales is interwoven into practical and theoretical aspects of scientific inquiry thus geomorphology is important to our understanding of not only physical systems but also fundamental concepts of time this study examines channel morphological changes in the bear and american basins brought about by two episodes of sedimentation from hydraulic gold mining the primary event was the production of more than 1 billion m3 of sediment throughout the northern sierra nevada from 1853 to 1884 which caused aggradation in many channels across the sierra foothills and sacramento valley assumptions by both engineers and geomorphologists that morphologic responses to this event were ephemeral that sediment loads have returned to previous levels and that deposits have stabilized are not borne out by field and historical data in the sacramento valley a secondary sedimentation event not previously studied was the production of at least 24 million m3 of sediment during a period of licensed mining from 1893 to 1953 this episode of sedimentation has been largely overlooked as a geomorphic hydrologic or water quality event yet channel morphologic responses in phase with mining during this period are demonstrated systematic changes in stage discharge relationships reflect channel morphological changes that are relevant to flood risk assessments stability of engineering structures on floodplains and geomorphic interpretations

characterising the spatial distribution frequency and geomorphic controls on landslide occurrence molise italy abstract an 815 km2 area in molise central italy was used as a natural laboratory to characterise the lithological topographic and fluvial controls on the spatial distribution and frequency of active landslides in temperate climates the study area is part of the central apennines fold and thrust belt and is characterised by the presence of a tectonic melange of scaly clays known as argille varicolori as well as more competent limestone and sandstone units the area has been subjected to a cumulative stream incision of up to 400 m since the mid pleistocene the landslide inventory was developed by combining satellite image interpretation and existing data sets ground truthed in the field statistical analysis of the inventory data demonstrates that the coupling between landslide occurrence in the area and lithology is strong with landslides occurring 3 10 times more frequently where the mechanically weak argille varicolori scaly clays outcrops compared to other lithologies analysis of the relationship between landslide occurrence and hillslope gradients shows that 50 of all landslides occur on slopes between 10 and 15 despite this interval representing only 30 of hillslope gradients in the study area these results demonstrate the major control that the properties of the regionally significant argille varicolori have on landslide occurrence in the area directly and through their control on hillslope gradients additionally our results show that more than 50 of the landslides occur at a distance of

susceptibility assessments of shallow earthflows triggered by heavy rainfall at three catchments by logistic regression analyses abstract sometimes regional meteorological anomalies trigger different types of mass movements in may 1998 the western black sea region of turkey experienced such a meteorological anomaly numerous residential and agricultural areas and engineering lifelines were buried under the flood waters besides the reactivation of many previously delineated landslides thousands of small scale landslides mostly the earthflow type occurred all over the region the earthflows were mainly developed in flysch type units which have already presented high landslide concentrations in this study three different catchments namely agustu egerci and kelemen were selected because they have the most landslide prone geological units of the region the purposes of the present study are to put forward the spatial distributions of the shallow earthflows triggered to describe the possible factors conditioning the earthflows and to produce the shallow earthflow susceptibility maps of the three catchments the unique condition units ucu were employed during the production of susceptibility maps and during statistical analyses the unique condition units numbered 4052 for the agustu catchment 13 241 for the egerci catchment and 12 314 for the kelemen catchment the earthflow intensity is the highest in the agustu catchment 0 038 flow ucu and lowest in the egerci catchment 0 0035 flow ucu logistic regression analyses were also employed however during the analyses some difficulties were encountered to overcome the difficulties a series of sensitivity analyses were performed based on some decision rules introduced in the present study considering the decision rules the proper ratios of ucu free from earthflow 0 ucu including the earthflow 1 for the agustu egerci and kelemen catchments were obtained as 3 6 and 5 respectively also a chart for the proper ratio selection was developed the regression equations from the selected ratios were then applied to the entire catchment and the earthflow susceptibility maps were produced the landslide susceptibility maps revealed that 15 of the agustu catchment 8 of the egerci catchment and 7 of the kelemen catchment have very high earthflow susceptibility and most of the earthflows triggered by the may 1998 meteorological event were found in the very high susceptibility zones

bounce rock a shergottite like basalt encountered at meridiani planum mars additional co authors thanasis economou steven p gorevan brian c hahn gostar klingelhofer timothy j mccoy harry y mcsween jr douglas w ming richard v morris daniel s rodionov steven w squyres heinrich wanke shawn p wright michael b wyatt albert s yen

multidisciplinary investigations in evaluating landslide susceptibility an example in the serchio river valley italy abstract the proposed experimental study is aimed at contributing to the landslide susceptibility evaluation using a multidisciplinary approach geological geomorphological and geo engineering survey together with multivariate statistical analysis and gis technique it is included in a wider research project aimed at defining the landslide hazard in the area of the map no 250 castelnuovo di garfagnana 1 50 000 scale this study is based on the realization of a landslides inventory map and statistical data analysis using probabilistic methods the methodology applied in ranking slope instability proceeded step by step at first geomorphologic investigation was performed in order to realize a landslide inventory map a gis database was created to collect the characteristics related to landslides geometry type of movement and state of activity geo engineering survey and characterization with in situ and laboratory tests allowed assessing rock mass classification and geotechnical properties of soils texture and consistency the statistical approach for evaluating the landslide susceptibility is based on the assumption that the landslide probability for the currently landslides free areas could be evaluated studying the conditions which led to past and present instability a set of environmental factors thought to be related to landslides were analysed and their spatial distribution organized in different layers then gis supported spatial analysis conditional and multivariate analysis allowed to calculate the connections between instability factors and landslide distribution this step evolved towards two distinct statistical methods both indirect and quantitative leading to a classification of the land surface in some different susceptibility domains conditional analysis was applied to a particular type of terrain unit named unique condition unit ucu that is a unique combination of the instability factors the computer aided evaluation of the landslide index within each ucu represents the probability of landslide occurrence according to bayes statistical concept multivariate analysis was applied to the same set of instability factors but to a different type of terrain unit the grid cell the results showed a quantitative response more reliable about the effectiveness of each instability factors with the possibility of verifying their statistical significance

digital photogrammetric analysis and electrical resistivity tomography for investigating the picerno landslide basilicata region southern italy abstract digital photogrammetric analysis and electrical resistivity tomography ert techniques were applied to evaluate the volume of material involved in a complex roto translational slide occurred in the territory of picerno basilicata region southern italy analytical and digital photogrammetric techniques facilitated a multi temporal analysis of aerial photos for the years 1997 2004 and 2006 in order to identify different geomorphologic features scarps terraces and trenches of the landslide and their development the analytical and digital photo interpretation was performed at the maximum scale of 1 5000 geological and geomorphological surveys were carried out to verify photo interpretation results digital elevation models dems for 1997 2004 and 2006 were produced by applying the grid adaptive method the differential dems 2006 1997 2006 2004 2004 1997 for the most dangerous part of the landslide allowed us to recognize the areas affected either by deposition or erosion and also estimate any altitudinal changes in each geomorphologic unit to detect the sliding surface and estimate the thickness of the sliding material several transversal and longitudinal ert profiles were obtained the electrical images of subsurface supported by stratigraphical data from boreholes were integrated with the information from the dems the altitudinal changes and the sizes of the source and accumulation areas allowed us to estimate the volume of material involved in the mass movement the fusion of data from different sensors allows us to gather indications on the surface and subsurface characteristics of the landslide providing useful information for landslide mitigation activities such an approach can help both to improve our knowledge and overcome the drawbacks of each methodology

the influence of the geological and geomorphological settings on shallow landslides an example in a temperate climate environment the june 19 1996 event in northwestern tuscany italy on june 19 1996 an extremely heavy rainstorm hit a restricted area in the apuan alps northwestern tuscany italy its max intensity concentrated over an area of about 150 km2 astride the apuan chain where 474 mm was recorded in about 12 h 21 of the mean annual precipitation with an intensity up to 158 mm h the storm caused floods and hundreds of landslides and debris flows which produced huge damage hundreds of millions of euros partially destroyed villages and killed 14 people this paper reports the results obtained from a detailed field survey and aerial view interpretation in the most severely involved area 647 main landslides were investigated mapped and related to the geologic geomorphic and vegetational factors of the source areas this was in order to define the influence of these factors and contribute to an evaluation of the landslide hazard in the study area an assessment was also made of the total area and volume of material mobilised by landsliding the study area about 46 km2 wide includes three typically mountainous basins characterised by narrow deep cut valleys and steep slopes where many rock types outcrop most of the landslides were shallow and linear referable to complex earth and debris translational slide which quickly developed into flow soil slip debris flow usually they involved colluvium and started in hollows underlain by metamorphic rock metasandstone and phyllite often dipping downslope therefore bedrock lithology and impermeability appeared to be important factors in the localisation of the landslide phenomena the investigation of the geomorphic and land use features in the source areas also frequently highlighted a rectilinear profile of the slope a high slope gradient 31 45 and dense chestnut wood cover in the area about 985 000 m2 2 1 of 46 km2 was affected by landsliding and about 700 000 m2 of this area was covered by chestnut forest the landslides removed about 7000 trees the volume of mobilised material was about 1 360 000 m3 about 220 000 m3 remained on the slopes while the rest poured into the streams in addition about 945 000 m3 was mobilised by the torrential erosion in the riverbeds

regional clastic sediment yield in british columbia the data archive of the water survey of canada supplemented by data of the british columbia hydro and power authority is used to investigate the areal pattern of fluvial sediment yield in british columbia the data represent suspended sediment loads at 63 stations derived from observations within the period 1966 1985 in most of the province there is a single annual peak in sediment transport in spring corresponding to the dominant snowmelt freshet however on the coast winter rainfall induces the sediment peak and in the coast and cascade mountains there is a transitional regime with two peaks from 65 to 90 of annual sediment yield occurs in the spring three months sediment yield per unit area specific sediment yield increases with drainage area at all scales from 10 up to 30 000 km2 the pattern persists seasonally throughout the year this contradicts the conventional model in which sediment yield declines downstream because of deposition along channels of a portion of the load derived from e

tailings fans and valley spur cutoffs created by hydraulic mining sand and gravel tailings from nineteenth century open pit hydraulic gold mines formed large alluvial fans at tributary con uences in the northwestern sierra nevada california in the bear river watershed several of these fans were so large that they blocked main channels for decades some channels not only aggraded deeply but also moved laterally and cut across the inner bends of valley spurs now locked in bedrock channels these valley spur cutoffs impose local controls on geomorphic hydraulic and sedimentary processes one cutoff has incised 25 m into bedrock over the past century 25 cm a 1 with rapid initial incision rates of up to 50 cm a 1 1884 1890 recognition of spur cutoffs in the geological record may help to identify large landslides and provide an analogue for a type of natural earth ll dam spillway not prone to catastrophic failures tailing fans valley spur cutoffs and the sediment they trap are described from contemporary accounts and recent eld conditions in the bear river watershed these anthropogenic changes represent a major shift in the watershed from supply limited to transport limited sediment budgets and a change in geomorphic processes away from long term drainage evolution dominated by ingrown meanders the large volumes of mining sediment stored in these landforms will be slowly released over the next millennium and could be signi cant to contemporary ecological and public health issues due to recent ndings of high mercury loadings associated with hydraulic mines copyright 2004 john wiley sons ltd

floodplain construction by recent rapid vertical accretion waipaoa river new zealand the rate of vertical accretion typically 14 18 mm h 1 during eight floods in the waipaoa river basin with recurrence intervals of 5 to 60 years was determined by relating the floodplain stratigraphy at mcphail s bend to the 1948 1995 flood history overbank deposits remaining after a flood that occurred in march 1996 suggest a rate of vertical accretion of 15 mm h 1 by contrast because the flow velocity across the floodplain was too high to permit deposition from suspension during the record flood of march 1988 the rate of vertical accretion was only 6 mm h 1 the sequence of deposition is highly discontinuous and the rapid vertical accretion is a response to a late 19th to early 20th century phase of deforestation in the headwaters that probably initiated a far greater change in suspended sediment yield than in discharge cross section surveys conducted since 1948 indicate that the high suspended sediment load of the waipaoa river also promoted in channel deposition which effected a progressive reduction in bankfull channel width although due to the overbank deposition channel capacity remained constant 1998 john wiley sons ltd

management responses to pulses of bedload sediment in rivers abstract rivers can experience sudden pulses of sediment from human and natural erosion processes that can accumulate in the bed abundant studies have examined the sources and dynamics of sediment pulses and problems caused by these pulses particularly flooding avulsions and habitat simplification much less has been written about what managers can do about sediment pulses and that is the purpose of this review the first option for managers is to do nothing and this decision can be informed by many case studies and by theory on the propagation and character of sediment pulses their diffusion translation and celerity doing nothing should be informed by the secondary effects of sediment pulses on channels including widening avulsions and tributary interactions if managers decide that something needs to be done about the sediment they have four options 1 reducing the sediment supply at source 2 trapping sediment in the channel 3 accelerating sediment transport through a reach and 4 directly extracting sediment the most common of these actions is undoubtedly to reduce the supply at source but there are few examples of the consequences of this for sediment pulses there are even fewer examples of trapping accelerating and extracting sediment all of these options have great potential for managing sediment pulses however they also have the potential to trigger incision of tributaries and of the channel behind the passing sediment wave overall the literature equips managers to understand the dynamics of sediment pulses but it does not yet equip them to confidently manage these geomorphic events

channel morphology and bedload pulses in braided rivers a laboratory study bedload pulses in gravel bed rivers have been widely reported in recent years and attempts have been made to relate them to channel morphology bedload transport and channel morphology were measured in a small scale generic model of braided gravel bed streams two experiments are described in which braided channels developed in a 14 m 3 m sand tray total bedload output from the tray was weighed every 15 minutes stream bed geometry was surveyed every four hours pulses were observed in the bedload output time series and were qualitatively related to the channel morphology immediately upstream of the measuring section the bagnold 1980 bedload equation generally overpredicts measured bedload transport rates when applied to channels that were in equilibrium or aggrading underprediction occurred when applied to degrading channels aggradation was associated with channel multiplication and bar deposition channel pattern simplification occurred when degradation took place and bars emerged from the water flow development of phases of aggradation and degradation is dependent upon the three dimensional geometry of the stream beds spatial and temporal feedback loops can be identified enabling links between channel morphology and bedload transport rate to be directly identified

a gis based automated procedure for landslide susceptibility mapping by the conditional analysis method the baganza valley case study italian northern apennines among the many gis based multivariate statistical methods for landslide susceptibility zonation the so called conditional analysis method holds a special place for its conceptual simplicity in fact in this method landslide susceptibility is simply expressed as landslide density in correspondence with different combinations of instability factor classes to overcome the operational complexity connected to the long tedious and error prone sequence of commands required by the procedure a shell script mainly based on the grass gis was created the script starting from a landslide inventory map and a number of factor maps automatically carries out the whole procedure resulting in the construction of a map with five landslide susceptibility classes a validation procedure allows to assess the reliability of the resulting model while the simple mean deviation of the density values in the factor class combinations helps to evaluate the goodness of landslide density distribution the procedure was applied to a relatively small basin 167 km2 in the italian northern apennines considering three landslide types namely rotational slides flows and complex landslides for a total of 1 137 landslides and five factors namely lithology slope angle and aspect elevation and slope bedding relations the analysis of the resulting 31 different models obtained combining the five factors confirms the role of lithology slope angle and slope bedding relations in influencing slope stability

a centennial tribute to g k gilbert s hydraulic mining debris in the sierra nevada abstract g k gilbert s 1917 classic monograph hydraulic mining debris in the sierra nevada is described and put into the context of modern geomorphic knowledge the emphasis here is on large scale applied fluvial geomorphology but other key elements e g coastal geomorphology are also briefly covered a brief synopsis outlines key elements of the monograph followed by discussions of highly influential aspects including the integrated watershed perspective the extreme example of anthropogenic sedimentation computation of a quantitative semidistributed sediment budget and advent of sediment wave theory although gilbert did not address concepts of equilibrium and grade in much detail the rivers of the northwestern sierra nevada were highly disrupted and thrown into a condition of nonequilibrium therefore concepts of equilibrium and grade for which gilbert s early work is often cited are discussed gilbert s work is put into the context of complex nonlinear dynamics in geomorphic systems and how these concepts can be used to interpret the nonequilibrium systems described by gilbert broad basin scale studies were common in the period but few were as quantitative and empirically rigorous or employed such a range of methodologies as pp105 none demonstrated such an extreme case of anthropogeomorphic change

differentiating the effects of logging river engineering and hydropower dams on flooding in the skokomish river washington usa abstract a decades long progressive loss of channel capacity in the skokomish river a 622 km2 basin draining the southeast olympic mountains of washington state has caused increasing flooding with severe consequences to endangered salmon runs infrastructure and private property to differentiate among multiple potential drivers of the capacity loss we analyze the geomorphic evidence for the potential effects of flow regulation by two dams constituting the cushman hydroelectric project which began regulating flow in the river s north fork in 1925 and diverting water out of the basin in 1930 sediment production from mid twentieth century logging in the river s south fork basin and twentieth century river engineering in the mainstem bankfull channel capacity in the mainstem has steadily declined since about 1940 from 370 m3 s 1 to

application of radar data to modeling rainfall induced landslides many shallow landslides are triggered by heavy rainfall previous studies of landslide modeling have been hampered by the scarcity of rain gauges to adequately depict the spatial variability of rainfall conditions triggering landslides this study simulates the efficiency of the critical rainfall model for landslide prediction in a mountainous watershed with inputs of different rainfall estimates associated with a typhoon tropical cyclone event doppler radar data at a spatial resolution of 1 km and measurements from six gauging stations provide the sources for rainfall estimates inverse distance weighted splines and kriging are the interpolation methods for gauged rainfall estimates a comparison of the simulation outputs shows that the model using radar rainfall estimates has a better performance than those using gauged rainfall estimates in predicting both landslides and stable areas in light of the results this paper also discusses the validity of the critical rainfall model for landslides in relation to its rainfall input and steady state hydrological assumption

landslides triggered by the 7 august 2009 typhoon morakot in southern taiwan abstract landslides triggered by typhoon morakot with an area over 576 m2 were mapped from formosat 2 images recognition and calculation of the number and area of landslides show that at least 22 705 landslides with a total area of 274 km2 were recognized in the 7811 km2 study area among these landslides 17 417 with a total area of 150 km2 are recognized as new ones and 5288 with a total area of 124 km2 are classified as enlarged from pre existing ones out of the 22 705 landslides there were 22 221 recognized with an area smaller than 10 ha 298 recognized in the range of 10 to 20 ha twenty two landslides with an area of over 60 ha have also been identified and the total area of these landslides is 20 km2 which is equal to 7 37 of the total landslide area with respect to exposed rock type the landslides mainly occurred in eocene miocene slate and miocene sandstone and shale in addition morakot induced landslides mainly occurred in areas with cumulative precipitation in the range of 800 to 2600 mm and the magnitude of landslide concentration is roughly linearly proportional to the amount of cumulative rainfall

designing forward with an eye to the past morphogenesis of the lower yuba river abstract the early geomorphic evolution of the lower yuba river lyr northern california up to 1906 is reconstructed using cartographic documentary topographic and stratigraphic evidence the importance of early river mining is identified along with rates and patterns of floodplain aggradation and channel incision at the turn of the 20th century the lyr is a classic example of anthropogeomorphic transformation of a river by episodic hydraulic mining sedimentation this was followed by channelization damming dredging and other engineering works to redirect contain and stabilize channels these geomorphic changes and engineering controls continue to govern channel and floodplain form and process control the trajectory of river responses and constrain flood control water quality and aquatic ecosystem management options returning a river system to a prior condition should not be the primary goal of river rehabilitation projects especially if hydrologic inputs have substantially changed reconstructing former conditions may be impractical and unsustainable under modern circumstances instead fluvial systems should be designed and managed for present inputs and processes while anticipating future conditions rapid changes in land use and climate that generate changes in runoff and sediment loadings are likely to generate morphological instability and these changes should be considered in the design and management of fluvial systems the past geomorphic evolution of fluvial systems should also be considered in design and management decisions to recognize trajectories and suppressed tendencies recognition of trends and system vulnerabilities may avoid potential blunders such as removing critical stabilizing works complex causalities may be difficult to reconstruct from geomorphic form alone however due to process form dynamics detailed research on the geomorphic and engineering history of a river is essential therefore if substantial changes and morphologic instabilities have occurred

relationship between groundwater flow estimated by soil temperature and slope failures caused by heavy rainfall shikoku island southwestern japan most of the slope failure disasters in a humid area such as that of japan are caused by heavy rain however even for the case of heavy rainfall that occurs once in every 10 years total area of slope failures seldom exceeds 10 of a watershed from this background we focused on the vein like groundwater flows that increase pore water pressure and clarified the relationship between distributions of slope failures and groundwater veins in this study a 1 m depth ground temperature survey and water chemistry analyses at springs and boreholes were conducted in zentoku area of shikoku island southwestern japan to grasp the distribution of groundwater veins and their sources subsequently slope stability was analyzed to investigate the relationship between groundwater veins and slope failures at study sites these results lead to the following conclusions the slope failures appear to concentrate around shallow groundwater veins and groundwater veins rising from deep layers this means that slope failures caused by these groundwater veins in addition to rainfall two types of groundwater originate in the deep layers one has short storage time as indicated by the fact that dissolved substances are low the other is stored for a lengthy period as noted by a high concentration of dissolved substances by combining the results of stability analyses and distribution of groundwater veins it is suggested that prediction of zones with high potential for slope failure can be more accurate

channel responses to varying sediment input a flume experiment modeled after redwood creek california article i nfo storage flume aggradation degradation at the reach scale a channel adjusts to sediment supply and flow through mutual interactions among channel form bed particle size and flow dynamics that govern river bed mobility sediment can impair the beneficial uses of a river but the timescales for studying recovery following high sediment loading in the field setting make flume experiments appealing we use a flume experiment coupled with field measurements in a gravel bed river to explore sediment transport storage and mobility relations under various sediment supply conditions our flume experiment modeled adjustments of channel morphology slope and armoring in a gravel bed channel under moderate sediment increases channel bed elevation increased and sediment output increased but channel planform remained similar to pre feed conditions during the following degradational cycle most of the excess sediment was evacuated from the flume and the bed became armored under high sediment feed channel bed elevation increased the bed became smoother mid channel bars and bedload sheets formed and water surface slope increased concurrently output increased and became more poorly sorted during the last degradational cycle the channel became armored and channel incision ceased before all excess sediment was removed selective transport of finer material was evident throughout the aggradational cycles and became more pronounced during degradational cycles as the bed became armored our flume results of changes in bed elevation sediment storage channel morphology and bed texture parallel those from field surveys of redwood creek northern california which has exhibited channel bed degradation for 30 years following a large aggradation event in the 1970s the flume experiment suggested that channel recovery in terms of reestablishing a specific morphology may not occur but the channel may return to a state of balancing sediment supply and transport capacity published by elsevier b v

incision and morphologic evolution of an alluvial channel recovering from hydraulic mining sediment hydraulic gold mining in the sierra nevada california produced such a large volume of sediment from 1853 to 1884 that channels could not carry a substantial proportion of the delivered sediment the lower bear river aggraded as much as 5 m and underwent a major avulsion during the 1870s channel morphology continues to respond to these changes more than 100 years after the cessation of most hydraulic mining textures of mine tailings and older alluvium are contrasted and channel incision and channel shape changes from 1930 to 1985 are documented unlike the yuba and sacramento rivers the lower bear river had not returned to pre mining base levels by 1950 as sediment loads decreased nor were incision rates or morphological change governed by reduced sediment loads below dams built in 1928 and in the mid 1960s channel stability was due to resistance of a cohesive stratum on the channel bed an episode of channel down cutting was instigated by a moderately large flood in december 1955 that pierced the cohesive layer and was sustained through the 1970s by moderate magnitude floods the 1955 flood did not directly erode large volumes of sediment but it destabilized the channel allowing smaller floods to erode the channel at an accelerated rate episodic channel bed incision is contrasted to progressive morphologic changes cross section shape narrowed and deepened steadily from 1930 through the mid 1970s as the channel was superimposed onto cohesive older alluvium progressive deepening set up a positive feedback that ensured the ultimate penetration of the paved bed channel morphologic readjustment from the avulsion thus was both progressive and episodic

unique meteorite from early amazonian mars water rich basaltic breccia northwest africa 7034 we report data on the martian meteorite northwest africa nwa 7034 which shares some petrologic and geochemical characteristics with known martian meteorites of the snc i e shergottite nakhlite and chassignite group but also has some unique characteristics that would exclude it from that group nwa 7034 is a geochemically enriched crustal rock compositionally similar to basalts and average martian crust measured by recent rover and orbiter missions it formed 2 089 0 081 billion years ago during the early amazonian epoch in mars9 geologic history nwa 7034 has an order of magnitude more indigenous water than most snc meteorites with up to 6000 parts per million extraterrestrial h2o released during stepped heating it also has bulk oxygen isotope values of 17o 0 58 0 05 per mil and a heat released water oxygen isotope average value of 17o 0 330 0 011 per mil suggesting the existence of multiple oxygen reservoirs on mars

channel incision on the lower american river california from streamflow gage records channel incision along the lower american river from 1905 to 1995 is investigated using channel cross section plots and statistical analysis of stage discharge data from two streamflow gages located at three sites channel incision lowered thalweg elevations at rates of up to 8 2 cm yr 1 and flow stages decreased at rates of up to 4 3 cm yr 1 for periods lasting several decades at a critical flood risk location in sacramento flow stages lowered 2 m from 1924 to 1970 channel incision was the result of channel recovery from aggradation due to hydraulic gold mining sediment and was exacerbated by sediment storage behind dams prolonged erosion and transport of historical alluvium in this river suggest that g k gilbert s symmetrical sediment wave model is inappropriate for the lower american river and may not adequately allow for the importance of sediment storage and remobilization in fluvial systems

ten conceptual models of large scale legacy sedimentation a review abstract considerable interest has been directed toward the recognition and documentation of legacy sediment i e anthropogenic sediment in fluvial systems little has been written however to identify implicit or explicit theories about how these deposits form and evolve over decennial to centennial time scales this review attempts to redress this void by examining conceptual models of the physical behavior and characteristics of catchment scale anthropic fluvial sedimentation events these concepts which are not unique to anthropogenic sediment include cascades sediment delivery ratios waves aggradation degradation episodes residence times budgets connectivity stream power nonlinear dynamical systems and geohistorical geoarchaeological and chronostratigraphic principles a broad definition of legacy sediment as episodically produced anthropogenic sediment is adopted that includes early episodes of large scale human induced sedimentation throughout the world the models apply to a variety of environments so the examples from north america following the introduction of european settlement can be related to other post settlement sedimentation episodes elsewhere during aggradation episodes rates of erosion and sedimentation often increased an order of magnitude in response to land clearance for agriculture timbering or mining these sediments may remain as a lasting geomorphic legacy that provides evidence of anthropogenic change and governs modern rates of sediment production and nonpoint source pollution

temporal variations in bedload transport rates associated with the migration of bedforms temporal variations in bedload transport rates that occur at a variety of timescales even under steady flow conditions are accepted as an inherent component of the bedload transport process rarely however has the cause of such variations been explained clearly we consider three data sets obtained from laboratory experiments that refer to measurements of bedload transport made with continuously recording bedload traps each data set is characterized by a predominant low frequency oscillation on which additional higher frequency oscillations generally are superimposed the period of these oscillations as isolated through the use of spectral analysts ranged between 0 47 and 168 minutes and was associated unequivocally with the migration of bedforms such as ripples dunes and bars the extent to which such oscillatory behaviour may be recognized in a data set depends on the duration of sampling and the length of the sampling time with respect to the period of a given bedform several theoretical probability distribution functions have been developed to describe the frequency distributions of relative bedload transport rates that are associated with the migration of bedforms einstein 1937b hamamori 1962 carey and hubbell 1986 these distribution functions were derived without reference to a sampling interval we present a modification of hamamori s 1962 probability distribution function generated by monte carlo simulation which permits one to specify the sampling interval in relation to the length of a bedform comparisons between the simulated and observed frequency distributions that were undertaken on the basis of the data described herein are good significant at the 90 per cent confidence level finally the implications that temporal variability which is associated with the migration of bedforms have for the accurate determination of bedload transport rates are considered

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

regolith structure analysis a contribution to understanding the local occurrence of shallow landslides austrian tyrol abstract this study focuses on shallow landslides on alpine slopes usually triggered by extreme rainfall events or rapid snowmelt shallow landslides cause soil loss of agricultural land and can even induce larger mass movements to estimate shallow landslide susceptibility it is crucial to understand the interactions of the conditioning factors the structure of the shallow subsurface regolith represents the least well known variable hydrological characteristics of the slope and its resulting stability depend very much on the structure and thickness of the regolith however conditions of the shallow subsurface have hitherto not been investigated in detail due to difficulties in area wide data collection by adapting a common method from engineering sciences our research provides new insights into the small scale structure of a regolith body on an alpine slope in the inner schmirn valley tyrol austria we carried out field measurements by applying densely spaced lightweight dynamic cone penetrometer tests dcpt on a test site of 30 m by 30 m to cope with the three dimensional 3d characteristics of the regolith body we suggest the application of a 3d volumetric lattice voxel model for the analysis of patterns and variations in the penetration resistance we propose a spatial interpolation by the regularized spline with tension rst method we approximated three different geotechnical parameters i the thickness of the local regolith ii the penetration resistance within the regolith and iii the surface of the solid bedrock an exploratory analysis allowed us to describe surface and bedrock morphology and to detect discontinuities in the regolith in the immediate vicinity of the landslide in addition we were able to establish a distinct spatial relation of the derived geotechnical parameters and slope failure the proposed method was developed tested and verified in an individual case study but the results indicate a great potential for future applications in shallow landslide susceptibility analysis the findings of this study improve knowledge on the relation between shallow subsurface structure and the occurrence of shallow landslides they also allow predictions about the potential evolvement of existing shallow landslides through secondary gliding processes

patterns of legacy sediment deposits in a small south carolina piedmont catchment usa abstract anthropogeomorphic changes to channels and floodplains occurred in response to destructive agricultural practices following the arrival of european settlers into the americas the southeastern piedmont physiographic region of the usa experienced severe erosion and sedimentation after settlement in the 1700s and farming up through the 1930s in places deep floodplain aggradation formed uninterrupted alluvial deposits that extend many kilometers this research examines anthropogenic impacts of land use change on valley bottom sedimentation in the chicken creek watershed of south carolina abrupt contacts between precolonial floodplain soils and a thick overburden of historical legacy sediment are common and well exposed throughout the two km study reach and provide clear evidence of extensive postcolonial sedimentation soil stratigraphic and sedimentologic evidence are presented to identify and contrast pre and postcolonial sediment characteristics and thicknesses lidar based spatial analysis is used to examine patterns of legacy sediment deposition and floodplain storage and together with field observations of bank stratigraphy examine the environments in which this occurred precolonial geomorphic stability is indicated by a buried soil epipedon ab horizon and other features on precolonial floodplain surfaces legacy sediment 2 to 4 m thick rests on top of exposed precolonial soils throughout the stream corridor with the pre postcolonial contact 1 5 m above the channel bed on average linear regression analysis shows that legacy sediment thickness varies statistically with changes in valley width and proximity to tributary sediment sources thin precolonial alluvium over bedrock suggests modest erosion and sedimentation rates prior to the arrival of euroamerican settlers mean grain sizes are similar between the pre and postcolonial alluvium but substantial contrasts in the degree of stratification and bulk density document differences between the respective depositional environments and post depositional changes to the two units channel adjustments since the time of maximum aggradation include bed incision to at least as low as the precolonial longitudinal profile and widening that is ongoing

geomorphic response to gravel augmentation and high flow dam release in the trinity river california the geomorphic effect of introducing a gravel augmentation totaling 520 m3 into a gravel bed stream during a dam controlled flood in may of 2015 was monitored with bedload transport measurements an array of seismometers and repeated topographic surveys half of the augmented gravel was injected into the flow with front end loaders on the rising limb of the flood and the other half was injected on the first day of the peak virtually all of the gravel transported past the injection point was deposited within about 7 to 10 channel widths of the injection point most of the injected gravel deposited along the left bank of the river whereas the right half of the channel bed was dominated by scour the downstream third of the depositional area consisted of a small dune field that developed prior to the second gravel injection and subsequently migrated about one channel width downstream a second depositional front was observed upstream from the gravel injection point where a delta like wedge of bed material developed in the first hours of the flow release and changed little over the remainder of the release these two depositional areas represent small scale bed material storage reservoirs with the potential to accumulate and periodically release packets of bed material interactions with such storage reservoirs are hypothesized to cause large bed material pulses to disperse by fragmenting into multiple smaller pulses as a refinement to the conceptual model that views sediment pulse evolution in terms of dispersion and translation the concept of pulse fragmentation has practical implications for gravel management it implies that gravel augmentations can produce morphologic changes at locations that are separated from the augmentation point by arbitrarily long reaches and it highlights the dependence of pulse propagation rates on the nature and distribution of the bed material storage reservoirs in the channel system copyright 2017 john wiley sons ltd

failure characteristics of rainfall induced shallow landslides in granitic terrains of shikoku island of japan soil slips debris slides and flow occurrences on hill slopes of particular areas are closely related to the mode of rainfall because of geological geomorphological and climatic settings japan is highly prone to rainfall induced landslides in 2004 shikoku the smallest island of japan faced extreme events of typhoon rainfalls and suffered huge losses of life and property because of floods and landslides this paper deals with the synoptic descriptions of failures that occurred in the granitic terrain of northeast shikoku island japan along with rainfall and failure relationships during the typhoon 0423 tokage of 2004 examples of typical failures that occurred in moriyuki and monnyu of northeast shikoku are taken into consideration in this study data from laboratory and field were used to perform sensitivity and stability analyses with respect to varying slope angles strength parameters and thicknesses of saturated residual soil this study attempts to employ a standard method of stability analysis of translational slides which are very common in masa soil weathered granite during extreme rainfall average rainfall intensities and duration during typhoon tokage were also used to interpret landslide triggering thresholds for the study area

sediment pulses in mountain rivers 1 experiments 1 sediment often enters rivers in discrete pulses associated with landslides and debris flows this is particularly so in the case of mountain streams the topographic disturbance created on the bed of a stream by a single pulse must be gradually eliminated if the river is to maintain its morphological integrity two mechanisms for elimination have been identified translation and dispersion according to the first of these the topographic high translates downstream according to the second of these it gradually diffuses away in any given river both mechanisms may operate this paper is devoted to a description of three controlled experiments on sediment pulses designed to model conditions in mountain streams each of the experiments began from the same mobile bed equilibrium with a set rate and grain size distribution of sediment feed in one experiment the median size of the pulse material was nearly identical to that of the feed sediment in the other two the pulse material differed in grain size distribution from the feed sediment being coarser in one case and finer in the other case in all cases the mode of pulse deformation was found to be predominantly dispersive a result that constitutes the main conclusion of this paper the pulses resulted in a notable but transient elevation of sediment transport rate immediately downstream when the pulse was coarser than the ambient sediment the bed downstream remained armored and a migrating delta formed in the backwater upstream when the pulse was finer than the ambient sediment translation was observed in addition to dispersion the presence of the finer material notably elevated the transport of ambient coarse material on the bed downstream in part 2 cui et al 2003 the experimental results are used to test a numerical model

evolution of a landslide induced sediment wave in the navarro river california a streamside landslide delivered 60 000 m3 of mixed size sediment to the navarro river a sinuous gravel bed channel drainage area 535 km2 at the end of the annual high runoff period in spring 1995 the deposit formed a 9 m high dam that partially breached within several hours but recessional flows entrained little material until the following high runoff season the landslide afforded the opportunity to measure the evolution of a sediment wave from its inception to near obliteration and particularly to test relative tendencies for translation and dispersion of a sediment wave in a natural gravel bed channel this study represents a simple case the wave originated from a single input the preexisting channel was relatively uniform and resistant banks prevented adjustments in width we surveyed channel topography over a 1 5 4 5 km reach centered on the landslide dam each year from 1995 to 1999 and we sampled bed material downstream of the dam in 1995 and 1997 landslide material was coarser than ambient bed material but all sizes were mobilized by subsequent peak flows abrasion of weathered and fractured graywacke sandstone landslide material was roughly an order of magnitude greater than the ambient river gravel the sediment wave dispersed and mostly disappeared within a few years with no measurable translation sediment filled the reservoir created by the eroding landslide dam until throughput of bed load was restored in 1998 the stationary wave crest eroded until in 1999 it was 1 m higher e mail dsutherl fs fed us than the preslide elevation as the wave profile flattened its detectable leading edge extended downstream from 620 m in 1995 to 1600 m in 1997 downstream advance of the wave was associated with coarsening of bed material the sediment wave created a longitudinal disturbance in sediment transport by using the dam as a reference datum of zero bed load transport we computed longitudinal variations in annual bed load and suspended sediment transport rates in 100 m increments downstream of the dam these longitudinal variations were controlled by scour and fill of the bed and by abrasion of bed load particles bed load transport rates in the first and second years after the landslide increased in the landslide vicinity and then decreased downstream as sediment deposited behind the advancing leading edge of the wave the location of peak bed load transport rate advanced from the first year 400 m to the second 800 m we used a physically based one dimensional model cui et al 2002b to hindcast annual changes in transversely averaged bed elevation over the study reach agreement between measured and predicted bed elevations was very good this result supports our conclusion that once emplaced sediment waves in gravel bed rivers tend to disperse with little or no translation

susceptibility and triggering scenarios at a regional scale for shallow landslides abstract the work aims at identifying susceptible areas and pluviometric triggering scenarios at a regional scale in calabria italy with reference to shallow landsliding events the proposed methodology follows a statistical approach and uses a database linked to a gis that has been created to support the various steps of spatial data management and manipulation the shallow landslide predisposing factors taken into account are derived from i the 40 m digital terrain model of the region an 15 075 km2 extension ii outcropping lithology iii soils and iv land use more precisely a map of the slopes has been drawn from the digital terrain model two kinds of covers prevalently coarse grained cg cover or fine grained fg cover were identified referring to the geotechnical characteristics of geomaterial covers and to the lithology map soilscapes were drawn from soil maps and finally the land use map was employed without any prior processing subsequently the inventory maps of some shallow landsliding events totaling more than 30 000 instabilities of the past and detected by field surveys and photo aerial restitution were employed to calibrate the relative importance of these predisposing factors the use of single factors first level analysis therefore provides three different susceptibility maps second level analysis however enables better location of areas susceptible to shallow landsliding events by crossing the single susceptibility maps on the basis of the susceptibility map obtained by the second level analysis five different classes of susceptibility to shallow landsliding events have been outlined over the regional territory 8 9 of the regional territory shows very high susceptibility 14 3 high susceptibility 15 moderate susceptibility 3 6 low susceptibility and finally about 58 very low susceptibility finally the maps of two significant shallow landsliding events of the past and their related rainfalls have been utilized to identify the relevant pluviometric triggering scenarios by using 205 daily rainfall series different triggering pluviometric scenarios have been identified with reference to cg and fg covers a value of 365 mm of the total rainfall of the event and or 170 mm d of the rainfall maximum intensity and a value of 325 mm of the total rainfall of the event and or 158 mm d of the rainfall maximum intensity are able to trigger shallow landsliding events for cg and fg covers respectively the results obtained from this study can help administrative authorities to plan future development activities and mitigation measures in shallow landslide prone areas in addition the proposed methodology can be useful in managing emergency situations at a regional scale for shallow landsliding events triggered by intense rainfalls through this approach the susceptibility and the pluviometric triggering scenario maps will be improved by means of finer calibration of the involved factors

modelling sediment transport as a moving wave the transfer and deposition of mining waste abstract the movement of slugs of bedload from a discrete input point down a river has proved difficult to model using conventional finite difference formulations of equations of motion a model is proposed which makes explicit allowance for the mean sediment velocity and through a dispersion coefficient the distribution of sediment velocity about the mean a second comparative model uses the normal mass conservation or sediment transport continuity approach the models have been tested over a 43 month period using data from seven monitored cross sections of the kawerong river on bougainville island papua new guinea a system which receives waste from a large copper mine the dispersion model performs considerably better than the mass conservation model

application of an integrated geotechnical and topographic monitoring system in the lorano marble quarry apuan alps italy abstract accurate slope stability analysis is essential for human activity in high risk geological contexts this may however not be enough in the case of quarrying where the dynamic and evolving environment also requires effective monitoring a well designed monitoring system requires the acquisition of a huge dataset over time improving knowledge of the study area and helping to refine prediction from stability analysis this paper reports the implementation of an integrated monitoring system in a marble quarry in the apuan alps italy and some of the results obtained the equipment consists of a traditional geotechnical monitoring system extensometers crackmeters and clinometers and two modern topographic monitoring systems a terrestrial interferometer and a robotic total station this work aims to provide in depth knowledge of the large scale rock mass behaviour as a result of marble exploitation thereby allowing continuous excavation the results highlight the importance of integrating different monitoring systems

historical erosion and sedimentation in two small watersheds of the southern blue ridge mountains north carolina usa sediment bodies produced during historical periods of human land use sometimes referred to as legacy sediment may be found in various locations within drainage basins and potentially remobilized by hydrogeomorphic processes accompanying land use change the amounts and locations of stored legacy sediment can be significant factors in modern drainage basin function and should be accounted for when possible in this study late nineteenth century erosion and sediment storage were investigated and used to construct approximate sediment budgets for two small blue ridge mountain drainage basins in north carolina usa erosion was quantified using a distributed implementation of the universal soil loss equation usle and calibrated on the separate bases of soil profile truncation data and recent published rates for long term erosion in the region sediment yield information was reconstructed from pond sediments trapped behind a mill dam alluvial sediment storage was quantified using field studies of streambank and floodplain sediment profiles and digital elevation data colluvial storage was calculated as a residual in the sediment budget and further evaluated using soil profile studies of footslope deposits and soil survey maps the proportions of erosion accounted for by the different budget terms in the most reliable budget are 28 sediment yield i e a sediment delivery ratio of 0 28 69 colluvial storage and 3 alluvial storage blue ridge basins with low levels of ground disturbance erode like piedmont basins at high levels of ground disturbance primarily due to higher slope angles sediment delivery ratio is high relative to those given for much larger basins in the adjacent and more frequently studied piedmont province and generally in accordance with published sediment delivery curves that reflect higher hydrogeomorphic connectivities within smaller basins low values for alluvial storage in blue ridge basins may be explained by high sediment transport within steep channels colluvial storage values have high uncertainties because of the well known problem of error accumulation in residual budget terms field data on colluvial deposits reported here are not sufficient to correct for this problem and in general the acquisition of accurate field data on historical colluviation remains an important methodological issue in historical sediment budgeting

magnitude and timing of downstream channel aggradation and degradation in response to a dome building eruption at mount hood oregon a dome building eruption at mount hood oregon starting in a d 1780 and lasting until ca 1793 produced dome collapse lithic pyroclastic flows that triggered lahars and intermittently fed 10 8 m 3 of coarse volcaniclastic sediment to sediment reservoirs in headwater canyons of the sandy river mobilization of dominantly sandy sediment from these reservoirs by lahars and seasonal floods initiated downstream migration of a sediment wave that resulted in a profound cycle of aggradation and degradation in the lowermost reach of the river depositional reach 61 87 km from the source stratigraphic and sedimentologic relations in the alluvial fill together with dendrochronologic dating of degradation terraces demonstrate that 1 channel aggradation in response to sediment loading in the headwater canyons raised the river bed in this reach at least 23 m in a decade or less 2 the transition from aggradation to degradation in the upper part of this reach roughly coincided with the end of the dome building eruption 3 fluvial sediment transport and deposition augmented by one lahar achieved a minimum average aggradation rate of 2 m yr 4 the degradation phase of the cycle was more prolonged than the aggradation phase requiring more than half a century for the river to reach its present bed elevation and 5 the present longitudinal profile of the sandy river in this reach is at least 3 m above the pre eruption profile the pattern and rate of channel response and recovery in the sandy river following heavy sediment loading resemble those of other rivers similarly subjected to very large sediment inputs the magnitude of channel aggradation in the lower sandy river greater than that achieved at other volcanoes following much larger eruptions was likely enhanced by lateral confinement of the channel within a narrow incised valley a combination of at least one lahar and winter floods from frequent moderate magnitude rainstorms and infrequent very large storms was responsible for flushing large volumes of sediment to the depositional reach these conditions permitted a sedimentation response in the sandy river that approached the magnitude of channel aggradation resulting elsewhere from large explosive eruptions and high intensity rainfall regimes despite the fact that the sandy river aggradation was in response to an unremarkable dome building eruption in a climate dominated by low to moderate rainfall intensities

probabilistic rainfall thresholds for triggering debris flows in a human modified landscape abstract in the carrara marble basin cmb apuan alps italy quarrying has accumulated widespread and thick quarry waste lying on steep slopes and invading valley bottoms the apuan alps are one of the rainiest areas in italy and rainstorms often cause landslides and debris flows the stability conditions of quarry waste are difficult to assess owing to its textural geotechnical and hydrogeological variability therefore empirical rainfall thresholds may be effective in forecasting the possible occurrence of debris flows in the cmb three types of thresholds were defined for three rain gauges of the cmb and for the whole area rainfall intensity rainfall duration id cumulated event rainfall rainfall duration ed and cumulated event rainfall normalized by the mean annual precipitation rainfall intensity emapi the rainfall events recorded from 1950 to 2005 was analyzed and compared with the occurrence of debris flows involving the quarry waste they were classified in events that triggered one or more debris flows and events that did not trigger debris flows this dataset was fitted using the logistic regression method that allows us to define a set of thresholds corresponding to different probabilities of failure from 10 to 90 and therefore to different warning levels the performance of the logistic regression in defining probabilistic thresholds was evaluated by means of contingency tables skill scores and receiver operating characteristic roc analysis these analyses indicate that the predictive capability of the three types of threshold is acceptable for each rain gauge and for the whole cmb the best compromise between the number of correct debris flow predictions and the number of wrong predictions is obtained for the 40 probability thresholds the results obtained can be tested in an experimental debris flows forecasting system based on rainfall thresholds and could have implications for the debris flow hazard and risk assessment in the cmb

regionalization of rainfall thresholds an aid to landslide hazard evaluation rainfall soil properties and morphology are major factors controlling shallow landsliding a series of meteorological events that triggered soil slips in northern italy were studied to define rainfall thresholds and to evaluate a possible regionalization soil properties triggering rainfall and local lithological and morphometrical settings of different sites were used as input to an infiltration model the approach allows the recognition of several triggering conditions in the piedmont pre alpine and alpine regions this suggests the need for different rainfall thresholds with respect to those derived with other methods intensity versus rainfall duration relationships become particularly important when related to soil permeability and thickness and demonstrate the role of antecedent precipitation events with exceptional water discharge from obstructed road culverts reveal the role played by anthropic structures in triggering such phenomena different approaches to slope stability analysis are shown taking into account bedrock lithology topography seepage and local saturation conditions

fluvial geomorphology a perspective on current status and methods fluvial geomorphology seeks to study river landform history understand formative processes and predict changes using a combination of field observation experimental studies and numerical models a resurgence in fluvial geomorphology is taking place fostered for example by its interaction with river engineering and the availability of new analytical methods instrumentation and techniques these have enabled development of new applications in river management landscape restoration hazard studies river history and geoarchaeology this paper presents a perspective on recent advances in fluvial geomorphology and introduces a selection of papers presented during the fluvial geomorphology and palaeohydrology session within the sixth international conference on geomorphology held in zaragoza spain in september 2005

regolith breccia northwest africa 7533 mineralogy and petrology with implications for early mars northwest africa 7533 a polymict martian breccia consists of fine grained clast laden melt particles and microcrystalline matrix while both melt and matrix contain medium grained noritic monzonitic material and crystal clasts the matrix also contains lithic clasts with zoned pigeonite and augite plus two feldspars microbasaltic clasts vitrophyric and microcrystalline spherules and shards the clast laden melt rocks contain clump like aggregates of orthopyroxene surrounded by aureoles of plagioclase some shards of vesicular melt rocks resemble the pyroxene plagioclase clump aureole structures submicron size matrix grains show some triple junctions but most are irregular with high intergranular porosity the noritic monzonitic rocks contain exsolved pyroxenes and perthitic intergrowths and cooled more slowly than rocks with zoned pyroxene or fine grain size noritic material contains orthopyroxene or inverted pigeonite augite calcic to intermediate plagioclase and chromite to cr bearing magnetite monzonitic clasts contain augite sodic plagioclase k feldspar ti bearing magnetite ilmenite chlorapatite and zircon these feldspathic rocks show similarities to some rocks at gale crater like black trout mara and jake m the most magnesian orthopyroxene clasts are close to alh 84001 orthopyroxene in composition all these materials are enriched in siderophile elements indicating impact melting and incorporation of a projectile component except for ni poor pyroxene clasts which are from pristine rocks clast laden melt rocks spherules shards and siderophile element contents indicate formation of nwa 7533 as a regolith breccia the zircons mainly derived from monzonitic melt rocks crystallized at 4 43 0 03 ga humayun et al 2013 and a 147sm 143nd isochron for nwa 7034 yielding 4 42 0 07 ga nyquist et al 2016 defines the crystallization age of all its igneous portions the zircon from the monzonitic rocks has a higher 17o than other martian meteorites explained in part by assimilation of regolith materials enriched during surface alteration nemchin et al 2014 this record of protolith interaction with atmosphere hydrosphere during regolith formation before melting demonstrates a thin atmosphere a wet early surface environment on mars and an evolved crust likely to have contaminated younger extrusive rocks the latest events recorded when the breccia was on mars are resetting of apatite much feldspar and some zircons at 1 35 1 4 ga bellucci et al 2015 and formation of ni bearing pyrite veins during or shortly after this disturbance lorand et al 2015