lithologic and glacially conditioned controls on regional debris flow sediment dynamics debris flow is an efficient process of sediment transfer from slope base to piedmont depositional fans in mountain drainage basins to advance understanding of debris flow sediment dynamics at the regional scale we analyze a historical 1998 2009 database of debris flows from 77 basins of alto adige province northeastern italy by combining information on event volumetric deposition high resolution digital topography and quaternary sediment mapping we are able to link debris flow sediment flux to morphometry lithologic variability and sediment availability we show that basin wide specific sediment yield ssy scales as an inverse power function of basin area this function is strongly controlled by the way rock type and abundance of quaternary deposits affect the rate of downstream sediment recruitment when sediment flux associated with each debris flow event is subsumed across discrete spatial increments of the entire region a complex sedimentary signature in the area ssy space is apparent that is ssy increases downstream up to areas as large as 1 km2 and starts to decline beyond this scale regardless of sediment availability we propose that this area ssy relation is characteristic of debris flow dominated settings

the significance of channel recharge rates for estimating debris flow magnitude and frequency the quantification of debris flow hazard requires estimates of debris flow frequency and magnitude several methods have been proposed to determine the probable volume of future debris flows from a given basin but most have neglected to account for debris recharge rates over time which may lead to underestimation of debris flow volumes in basins with rare debris flows this paper deals with the determination of debris recharge rates in debris flow channels based on knowledge of debris storage and the elapsed time since the last debris flow data are obtained from coastal british columbia and a relation is obtained across a sample of basins with similar terrain and climatic conditions for rennell sound on the west coast of the queen charlotte islands the power law relation for area normalized recharge rate rt versus elapsed time te was rt 0 23te 0 58 with an explained variance of 75 per cent a difference in recharge rates may exist between creeks in logged and unlogged forested terrain the power function for undisturbed terrain was rt 0 20te 0 49 while the function for logged areas was rt 0 30te 0 77 this result suggests that for the same elapsed time since the last debris flow clearcut gullies tend to recharge at a slower rate than creeks in old growth forest this finding requires verification particularly for longer elapsed times since debris flow but would have important implications for forest resource management in steep coastal terrain this study demonstrates that commonly used encounter probability equations are inappropriate for recharge limited debris flow channels copyright 2005 john wiley sons ltd

spatial distribution of sediment storage types and quantification of valley fill deposits in an alpine basin reintal bavarian alps germany spatial patterns of sediment storage types and associated volumes using a novel approach for quantifying valley fill deposits are presented for a small alpine catchment 17 km 2 in the bavarian alps the different sediment storage types were analysed with respect to geomorphic coupling and sediment flux activity the dominant landforms in the valley in terms of surface area were found to be talus slopes sheets and cones followed by rockfall deposits and alluvial fans and plains more than two thirds of the talus slopes are relict landforms completely decoupled from the geomorphic system notable sediment transport is limited to avalanche tracks debris flows and along floodplains sediment volumes were calculated using a combination of polynomial functions of cross sections seismic refraction and gis modelling a total of 66 seismic refraction profiles were carried out throughout the valley for a more precise determination of sediment thicknesses and to check the bedrock data generated from geomorphometric analysis we calculated the overall sediment volume of the valley fill deposits to be 0 07 km 3 this corresponds to a mean sediment thickness of 23 3 m the seismic refraction data showed that large floodplains and sedimentation areas which have been developed through damming effects from large rockfalls are in general characterised by shallow sediment thicknesses 20 m by contrast the thickness of several talus slopes is more than twice as much for some locations e g narrow sections of valley the polynomial generated cross sections resulted in overestimations of up to one order of magnitude whereas in sections with a moderate valley shape the modelled cross sections are in good accordance with the obtained seismic data for the quantification of valley fill deposits a combined application of bedrock data derived from polynomials and geophysical prospecting is highly recommended d 2003 elsevier b v all rights reserved

processes and rates of sediment and wood accumulation in headwater streams of the oregon coast range usa channels that have been scoured to bedrock by debris flows provide unique opportunities to calculate the rate of sediment and wood accumulation in low order streams to understand the temporal succession of channel morphology following disturbance and to make inferences about processes associated with input and transport of sediment dendrochronology was used to estimate the time since the previous debris flow and the time since the last stand replacement fire in unlogged basins in the central coast range of oregon debris flow activity increased 42 per cent above the background rate in the decades immediately following the last wildfire changes in wood and sediment storage were quantified for 13 streams that ranged from 4 to 144 years since the previous debris flow the volume of wood and sediment in the channel and the length of channel with exposed bedrock were strongly correlated with the time since the previous debris flow wood increased the storage capacity of the channel and trapped the majority of the sediment in these steep headwater streams in the absence of wood channels that have been scoured to bedrock by a debris flow may lack the capacity to store sediment and could persist in a bedrock state for an extended period of time with an adequate supply of wood low order channels have the potential of storing large volumes of sediment in the interval between debris flows and can function as one of the dominant storage reservoirs for sediment in mountainous terrain copyright 2003 john wiley sons ltd

landscape form and millennial erosion rates in the san gabriel mountains ca abstract it has been long hypothesized that topography as well as climate and rock strength exert first order controls on erosion rates here we use detrital cosmogenic 10 be from 50 basins ranging in size from 1 to 150 km 2 to measure millennial erosion rates across the san gabriel mountains in southern california where a strong e w gradient in relief compared to weak variation in precipitation and lithology allow us to isolate the relationship between topographic form and erosion rate our erosion rates range from 35 to 1100 m ma and generally agree with both decadal sediment fluxes and long term exhumation rates inferred from low temperature thermochronometry catchment mean hillslope angle increases with erosion rate until 300 m ma at which point slopes become invariant with erosion rate although this sort of relation has been offered as support for non linear models of soil transport we use 1 d analytical hillslope profiles derived from existing soil transport laws to show that a model with soil flux linear in slope but including a slope stability threshold is indistinguishable from a non linear law within the scatter of our data catchment mean normalized channel steepness index increases monotonically though non linearly with erosion rate throughout the san gabriel mountains even where catchment mean hillslope angles have reached a threshold this non linearity can be mostly accounted for by a stochastic threshold incision model though additional factors likely contribute to the observed relationship between channel steepness and erosion rate these findings substantiate the claim that the normalized channel steepness index is an important topographic metric in active ranges

persistent alluvial fanhead trenching resulting from large infrequent sediment inputs we present laboratory and field evidence that in mountainous catchment fan systems persistent alluvial fanhead aggradation and trenching may result from infrequent large sediment inputs we suggest that the river fan systems along the fault bounded range front of the western southern alps new zealand are likely to be in a dynamic equilibrium on 103 yr timescales superimposed on which their fanheads undergo long term cumulative episodic aggradation these fanheads are active only in rare events do not take part in the usual behaviour of the catchment fan system and require much longer to exhibit dynamic equilibrium than the rest of the fan these findings 1 increase our knowledge of the effects of extreme events on alluvial fan morphodynamics in humid climates 2 question the general applicability of inferring past climatic or tectonic regimes from alluvial fan morphology and stratigraphy and 3 provide a conceptual basis for hazard zonation on alluvial fans copyright 2006 john wiley sons ltd

on causes and impacts of land subsidence in bandung basin indonesia the bandung basin is a large intra montane basin surrounded by volcanic highlands in western java indonesia inhabited by more than seven million people the basin an area of about 2 300 km2 is a highland plateau at approximately 650 700 m above sea level and is surrounded by up to 2 400 m high late tertiary and quaternary volcanic terrain based on the results of nine gps surveys conducted since 2000 up to 2011 it was shown that several locations in the bandung basin have experienced land subsidence with an average rate of about 8 cm year and can go up to about 23 cm year in certain locations a hypothesis has been proposed by several studies that land subsidence observed in several locations in the bandung basin has been caused mainly by excessive groundwater extraction it is found that there is a strong correlation between the rates of groundwater level lowering with the gps derived rates of land subsidence in several locations in bandung basin the gps results in this study detected significant subsidence in the textile industry area where very large volumes of groundwater are usually extracted the impact of land subsidence in bandung can be seen in several forms mainly in the cracking and damage of houses buildings and infrastructure land subsidence also aggravates the flooding in bandung basin which has brought huge economic losses and deteriorated the quality of life and environment in the affected areas

erosion of steepland valleys by debris flows episodic debris flows scour the rock beds of many steepland valleys along recent debris flow runout paths in the western united states we have observed evidence for bedrock lowering primarily by the impact of large particles entrained in debris flows this evidence may persist to the point at which debris flow deposition occurs commonly at slopes of less than 0 03 0 10 we find that debris flow scoured valleys have a topographic signature that is fundamentally different from that predicted by bedrock river incision models much of this difference results from the fact that local valley slope shows a tendency to decrease abruptly downstream of tributaries that contribute throughgoing debris flows the degree of weathering of valley floor bedrock may also decrease abruptly downstream of such junctions on the basis of these observations we hypothesize that valley slope is adjusted to the long term frequency of debris flows and that valleys scoured by debris flows should not be modeled using conventional bedrock river incision laws we use field observations to justify one possible debris flow incision model whose lowering rate is proportional to the integral of solid inertial normal stresses from particle impacts along the flow and the number of upvalley debris flow sources the model predicts that increases in incision rate caused by increases in flow event frequency and length as flows gain material downvalley are balanced by rate reductions from reduced inertial normal stress at lower slopes and stronger less weathered bedrock these adjustments lead to a spatially uniform lowering rate although the proposed expression leads to equilibrium long profiles with the correct topographic signature the crudeness with which the debris flow dynamics are parameterized reveals that we are far from a validated debris flow incision law however the vast extent of steepland valley networks above slopes of 0 03 0 10 illustrates the need to understand debris flow incision if we hope to understand the evolution of steep topography around the world

geologic versus wildfire controls on hillslope processes and debris flow initiation in the green river canyons of dinosaur national monument abstract as in many areas of high relief debris flows are an important process linkage between hillslopes and the green river in the canyons of the eastern uinta mountains yet the physical conditions that lead to debris flow initiation are unknown a recent episode of enhanced debris flow and wildfire activity provided an opportunity to examine the geomorphic impact of fire and the processes by which weathered bedrock is transported to the green river field investigations and analysis of elevation and precipitation data were undertaken in 15 catchments with recent debris flows to determine how surficial geology wildfire topography bedrock strength and meteorology influence hillslope processes the recent debris flows were triggered by intense summer rainstorms the dominant debris flow initiation mechanism the firehose effect occurred when overland flow generated on bedrock hillslopes cascaded down steep cliffs onto colluvium causing failure sixty percent of the debris flows occurred in unburned catchments however 15 of the burned catchments in the study area produced debris flows over the study period whereas only 7 of the unburned catchments did thus fire was not the primary driver of debris flows but fire related events did contribute to the increased debris flow activity the geomorphic impact of wildfire in the eastern uinta mountains is not as great as in transport limited settings with regolith mantled hillslopes the strong rocks and dry climate of the study area cause hillslopes to be very steep and weathering limited with high runoff ratios and a dearth of regolith as a result there is little vegetation and thus we hypothesize that burning does little to change hillslope processes the suite of hillslope processes in the eastern uintas are like those documented in the similarly dry grand canyon but differ from other locations in the western u s where wildfire is a primary control on debris flow processes

a probabilistic sediment cascade model of sediment transfer in the illgraben we present a probabilistic sediment cascade model to simulate sediment transfer in a mountain basin illgraben switzerland where sediment is produced by hillslope landslides and rockfalls and exported out of the basin by debris flows and floods the model conceptualizes the fluvial system as a spatially lumped cascade of connected reservoirs representing hillslope and channel storages where sediment goes through cycles of storage and remobilization by surface runoff the model includes all relevant hydrological processes that lead to runoff formation in an alpine basin such as precipitation snow accumulation snowmelt evapotranspiration and soil water storage although the processes of sediment transfer and debris flow generation are described in a simplified manner the model produces complex sediment discharge behavior which is driven by the availability of sediment and antecedent wetness conditions system memory as well as the triggering potential climatic forcing the observed probability distribution of debris flow volumes and their seasonality in 2000 2009 are reproduced the stochasticity of hillslope sediment input is important for reproducing realistic sediment storage variability although many details of the hillslope landslide triggering procedures are filtered out by the sediment transfer system the model allows us to explicitly quantify the division into transport and supply limited sediment discharge events we show that debris flows may be generated for a wide range of rainfall intensities because of variable antecedent basin wetness and snowmelt contribution to runoff which helps to understand the limitations of methods based on a single rainfall threshold for debris flow initiation in alpine basins

assessments of land subsidence in the gippsland basin of australia using alos palsar data abstract in this paper the land deformation in the gippsland basin victoria australia has been mapped using the interferometric synthetic aperture radar insar time series analysis with the alos l band sar data land subsidence in the basin resulting from mining activities has already been known over the past few decades there has been ongoing concern that irrigation and off shore oil and natural gas extraction has significantly lowered groundwater levels on shore and that this may lead to further subsidence therefore it is important to map the land surface change in the basin in order to understand the actual impact of these activities the total area of gippsland basin is approximately 46 000 km2 where approximately one third of the basin is located onshore because of the large area of the basin alos palsar data from 4 different paths were used to map the land displacement over the basin the insar result suggests that the land displacement at 98 of the measurement points in the basin was between 10 mm year and 10 mm year the insar result has been compared to the ground survey data in several areas collected with gps and total station surveys the comparison of results suggested that the insar measurement and the ground survey measurement agree with each other in general the standard deviation of difference between the insar results and the ground survey data is approximately 4 mm year near the coastal area and 15 mm year near the mining sites several rapidly deforming areas have been identified at the mining sites and the surrounding areas deformation rate at up to 82 9 mm year is observed in these areas the deformation at the mining sites and the surrounding areas are expected to be resulted from mining activities and associated mine dewatering moreover several minor displacement zones have been observed and investigated in the area between the loy yang mines and the gippsland coast as well as the area between yanakie and wilsons promontory

quantitative reconstruction of late holocene surface evolution on an alpine debris flow fan debris flow fans form a ubiquitous record of past debris flow activity in mountainous areas and may be useful for inferring past flow characteristics and consequent future hazard extracting information on past debris flows from fan records however requires an understanding of debris flow deposition and fan surface evolution field scale studies of these processes have been very limited in this paper we document the patterns and timing of debris flow deposition on the surface of the large and exceptionally active illgraben fan in southwestern switzerland we use terrain analysis radiocarbon dating of sediment fill in the illgraben catchment and cosmogenic 10be and 36cl exposure dating of debris flow deposits on the fan to constrain the temporal evolution of the sediment routing system in the catchment and on the fan during the past 3200 years we show that the fan surface preserves a set of debris flow lobes that were predominantly deposited after the occurrence of a large rock avalanche near the fan apex at about 3200 years ago this rock avalanche shifted the apex of the fan and impounded sediment within the illgraben catchment subsequent evolution of the fan surface has been governed by both lateral and radial shifts in the active depositional lobe revealed by the cosmogenic radionuclide dates and by cross cutting geometrical relationships on the fan surface this pattern of frequent avulsion and fan surface occupation provides field scale evidence of the type of large scale compensatory behavior observed in experimental sediment routing systems

hydrogeomorphic processes in a steep debris flow initiation zone 1 many debris flows initiate in steep channels 20 degrees yet studies have focused on lower gradient streams where failure is controlled by water height above channel deposits multiple debris flows in a steep channel in ohya landslide central japan were linked to infilling processes i e freeze thaw and dry ravel and partial saturation of accumulated sediment because of very active geomorphic processes in this catchment 39 debris flows were observed in the past 6 yr pre and post event imagery indicates selective transport of finer materials during most debris flows that comprise saturated and unsaturated flows however fluvial sediment processes important in relation to debris flow initiation in gentler channels were minimal critical conditions for the movement of such unsaturated materials are derived by equating shear stress with solid friction of the channel bed

from gullies to mountain belts a review of sediment budgets at various scales this paper reviews the state of the art in the concept as well as in the application of sediment budgets in sedimentary research sediments are a product of mass dispersal at the earth surface and take part in global cycles sediment budgets aim at quantifying this mass transfer based on the principle of mass conservation and are the key to determine ancient fluxes of solid matter at the earth surface this involves fundamental questions about the interplay of uplift climate and denudation in mountain belts and transfer of sediments from the continents to the oceans as well as applied issues such as soil and gully erosion reservoir siltation and coastal protection first after introducing basic concepts relevant scales and methodologies the different components of quaternary routing systems from erosion in headwaters river systems glacial and paraglacial systems lakes deltas estuaries coasts shelves epicontinental seas and deep sea fans are discussed in terms of their sediment budget most suitable are sedimentologically closed or semi closed depositional environments e g alluvial fans lakes deltas and deep sea fans in a second step the dynamics of passive active and collisional tectonic settings and sediment budgets in related sedimentary basins are explored and new concepts of sediment portioning at large geodynamic scales are introduced ancient routing systems are more or less incomplete and may be intensively fragmented or destroyed in active tectonic settings in terms of sedimentary basin types rifts intracontinental and epicontinental settings are preferred objects of sediment budgets because of their persistence and relatively simple overall sedimentary architecture however closing basins such as foreland forearc retroarc piggy back and wedge top basins may provide excellent snapshots of orogenic sediment fluxes in a third step the large long lived routing systems of the amazon the ganges brahmaputra and the rhine are reviewed for each system estimates of either sediment volumes mass or sediment fluxes of continental and marine subsystems have been compiled in order to receive a complete routing in terms of mass conservation for specific time periods since the late glacial maximum as well as the cenozoic following lessons can be taken from these case studies i depositional centers and fluxes show strong shifts in space and time and call for caution when simply looking at subsystems ii the response times of these large systems are within the milankovich time interval thus lower than predicted from diffusion models iii cyclic routing of sediments in continental basins is much more dominated by climate human control than by eustacy and iv at long time scales ultimate sinks win over intermittent storage it is concluded from this review that the quantitative understanding of global sediment cycling over historic and geologic time and its response to allogenic forcing is still in its infancy and further research is needed towards a holistic view of sediment routing systems at various temporal and spatial scales and their coupling with global biogeochemical cycles this includes i to better determine response times of large routing systems by linking quaternary with cenozoic sediment budgets and continental with marine sub systems ii to combine advanced provenance techniques with sediment budgets in order to reconstruct ancient systems iii to study sediment partitioning at the basin scale iv to reconcile continental supply dominated sequence stratigraphy with the eustatic dominated marine concept and iv to account for non actualism of ancient systems with respect to their erosion and transport mode in particular during glaciations and pronounced arid intervals glacial and eolian sediment routing may cross over hydrologic boundaries of drainage basins thus challenging the principle of mass conservation

sources of debris flow material in burned areas abstract the vulnerability of recently burned areas to debris flows has been well established likewise it has been shown that many if not most post fire debris flows are initiated by runoff and erosion and grow in size through erosion and scour by the moving debris flow as opposed to landslide initiated flows with little growth to better understand the development and character of these flows a study has been completed encompassing 46 debris flows in california utah and colorado in nine different recently burned areas for each debris flow progressive debris production was measured at intervals along the length of the channel and from these measurements graphs were developed showing cumulative volume of debris as a function of channel length all 46 debris flows showed significant bulking by scour and erosion with average yield rates for each channel ranging from 0 3 to 9 9 m 3 of debris produced for every meter of channel length with an overall average value of 2 5 m 3 m significant increases in yield rate partway down the channel were identified in 87 of the channels with an average of a three fold increase in yield rate yield rates for short reaches of channels up to several hundred meters ranged as high as 22 3 m 3 m debris was contributed from side channels into the main channels for 54 of the flows with an average of 23 of the total debris coming from those side channels rill erosion was identified for 30 of the flows with rills contributing between 0 1 and 10 5 of the total debris with an average of 3 debris was deposited as levees in 87 of the flows with most of the deposition occurring in the lower part of the basin a median value of 10 of the total debris flow was deposited as levees for these cases with a range from near zero to nearly 100 these results show that channel erosion and scour are the dominant sources of debris in burned areas with yield rates increasing significantly partway down the channel side channels are much more important sources of debris than rills levees are very common but the size and effect on the amount of debris that reaches a canyon mouth is highly variable

a morphometric analysis of gullies scoured by post fire progressively bulked debris flows in southwest montana usa in the fall of 2001 an intense thunderstorm in southwest montana triggered many debris flows in the burned area of sleeping child creek in most instances the debris flows cut deep gullies into previously unchannelized colluvial hollows and deposited large volumes of sediment onto the valley floor the presence of rill networks above the gullies as well as the absence of landslide features indicate that the gullies were scoured by progressively bulked debris flows a process in which dilute surface runoff becomes increasingly more laden with sediment until it transforms into a debris flow in this contribution we present a morphometric analysis of six of the gullies to better understand this relatively understudied process we find that the locations of the rill heads and gully heads conform to slope area thresholds that are characteristic of erosion by overland flow our data also suggest that the volumes of the debris flows increase exponentially with normalized drainage area thus lending support to an assumption used in a recently proposed debris flow incision law finally the debris flow fans have been relatively unaltered since deposition suggesting that the valley may be currently aggrading while the hillslopes are being denuded

the role of debris supply conditions in predicting debris flow activity debris flow frequency and magnitude were determined for 33 basins in southwest british columbia basins were first classifiedaseitherweathering limitedortransport limitedusingadiscriminantfunctionbasedondebris contributingarea an area weighted terrain stability number and drainage density multiple regression was used to predict magnitude peak discharge frequency and activity frequency times magnitude within each group of basins model performance was improved by stratifying the total sample of debris flow basins into weathering and transport limited groups explained varianceincreasedbyanaverageof15percentinthetransport limitedsample indicatingthatsedimentsupplyconditionsin themoreactivebasinsarefundamentalinpredictingdebrisflowactivity anindependenttestoftheregressionmodelswith 11basinsyieldedgenerallygoodresultsfordebrisflowmagnitudeandpeakdischarge predictionofdebrisflowfrequency provedproblematicalinweathering limitedbasins themethodsdevelopedhereprovideestimatesofdebrisflowattributes in basins for which few data on past events are available copyright 1999 john wiley sons ltd

advances in holocene mountain geomorphology inspired by sediment budget methodology the sediment budget which links sediment sources to sediment sinks with hydroclimatic and weathering processes mediating the response is applied to the analysis of sediments in three alpine lakes in british columbia we provide two ways of using the sediment budget as an integrating device in the interpretation of mountain geomorphology these approaches differ in their resolution and ability to budget the major components of the fine sediment cascade in glaciated environments taken together they provide an integrated index of landscape change over the holocene the first example compares the hydroclimatic controls of lake sedimentation for the last 600 years a d 1370 1998 preserved in varved sediments from two of the lake basins this hydroclimatological approach incorporates contemporary monitoring air photo analysis and detailed stratigraphy of sedimentation events within a single varve to infer the timing sources and preferred pathways of fine grained sediments reaching the lake basins the results indicate that glaciers hillslope and channel instability within the major subbasins are the principal sediment sources to the lake basins transitory sediment storage of glacially derived sediments within the channels is believed to modulate the episodic and more frequent delivery of sediments from adjacent hillslope and fluvial storage sites and direct routing of glacial rock flour during years of prolonged glacial melt the second example relying on the phosphorus geochemistry of sediments in an alpine lake basin considers the evolution of phosphorus forms from mineral to occluded and organic fractions as a function of the soil development inherent slope instability and repeated cycles of glaciation and neoglaciation over the holocene this geochemical approach demonstrates that both neoglaciation and full glaciation have essentially zeroed the system in such a way that a high proportion of mineral phosphorus remains in the present lake sediments and the bioavailability of phosphorus a key to ecosystem development is low both examples illustrate the importance of variable sediment sources the seasonality frequency and magnitude of sediment transfers and the profound influence of ice cover over contemporary neoglacial and pleistocene time scales they also signal the value of including both clastic and dissolved components in the sediment budget d 2003 elsevier science b v all rights reserved

linkage of sediment supply and transport processes in miyagawa dam catchment japan 1 linkages between sediment supply by episodic geomorphic processes obtained from aerial photographs and field surveys and sediment transport estimated from changes in sediment deposition behind a large dam were investigated in the miyagawa dam catchment central japan a total of 6667 landslides were confirmed in the period from 1965 to 2000 on the basis of seven temporal pairs of aerial photographs both the occurrence of landslides and discharge into the dam lake affect sediment yield indicating that fluvial systems in miyagawa dam catchment are supply limited with respect to sediment sediment yields are affected by not only the initial failed volume of landslides but also the mobility of landslides and debris flows in miyagawa dam catchment percentages of landslides reaching channels varied from 56 in 1997 2000 to 75 in 1976 1981 and were correlated with maximum hourly rainfall in addition the mobility of debris flows was higher during periods with high maximum instantaneous discharge compared to lower discharge suggesting that the water content both in initially failed materials and transported sediment controlled their mobility topography also affected the mobility of landslides debris flows for catchments 0 1 km2 the percentage of channel network length impacted by debris flows decreased with increasing catchment area due to reduced channel gradient thus both the magnitude of rainfall runoff events and the catchment topography affect how landslide sediment contributes to sediment yield at the large catchment scale

reduced sediment supply in a fast eroding landscape a multi proxy sediment budget of the upper rhone basin central alps alpine water and sediment supply influence the sediment budget of many important european fluvial systems such as the rhine rhone and po rivers in the light of human induced climate change and landscape modification it becomes increasingly important to understand the mechanisms of sediment production and supply in alpine sediment systems this study aims to investigate the modern sediment budget of the upper rhone basin one of the largest alpine intramontane watersheds located in the central alps of southwestern switzerland major areas of sediment generation are fingerprinted by framework petrography heavy mineral concentrations and bulk geochemistry the relative contributions of the three major sources to the sediment of the trunk rhone river are identified by compositional mixing modelling concentrations of the terrestrial cosmogenic nuclide 10be measured in quartz separated from fluvial sediments provide spatially averaged denudation rates for selected tributary basins results from sediment fingerprinting and mixing modelling suggest that tributaries located in the north and the east of the catchment are generating most of the sediment transported by the rhone river to its primary sedimentary sink in lake geneva despite having some of the highest denudation rates within the basin tributaries located in the southern area of the rhone basin are relatively underrepresented in the sediment budget of the rhone river these tributaries are severely affected by human activities for example through sediment mining as well as water and sediment abstraction in large hydropower reservoirs together these processes reduce the basin wide sediment discharge by about 50 thereby explaining most of the observed compositional pattern in addition there is evidence suggesting that large amounts of glaciogenic sediments are currently supplied by retreating glaciers glaciogenic material with its low 10be concentrations can lead to a significant overestimation of denudation rates and thus limit the applicability of cosmogenic nuclide analysis in such glaciated settings

groundwater derived land subsidence in the north china plain land subsidence usually bears strong relationship to abstraction of underground fluid land subsidence occurs commonly in the north china plain ncp and has become a major environmental factor hindering regional sustainable development this paper focuses on issues associated with mechanism of land subsidence in the ncp the analysis shows that multi layer aquifer systems with deep confined aquifers and the thick normally consolidated or unconsolidated compressible clay layers are the key of geological and hydrogeological conditions favorable for the development of land subsidence in the ncp groundwater withdrawal results in an increase in the distribution of effective stress within the strata and the compression of the aquifers and the confining layers and then triggers land subsidence in the middle east plain of the ncp the land subsidence volume approximately represents the amount of water released from compression of deep aquifers and aquitards in that land subsidence is primarily caused by excessive groundwater withdrawal in deep aquifer system the percentage of water released from compression of aquifers and aquitards in deep groundwater abstraction is significant but distinct in cangzhou city and in the whole middle east plain this is due to the difference in local lithological structure and recharge and discharge conditions of deep groundwater system the hysteresis of land subsidence is also discussed in typical areas and the results reveal that the time for completing the primary consolidation ranges from less than one year to tens of years and that the rate of secondary compression tends to increase with the moisture content

field observations of a debris flow event in the dolomites a debris flow event occurred in june 1997 in the dolomites eastern alps italy the phenomenon was directly observed in the field and recorded by a video camera near its initiation area the debris flow originated shortly after an intense rainstorm 25 mm in 30 min whose runoff mobilised the loose coarse debris that filled the bottom of the channel in its upper part the analysis of the steep headwater basin indicates a very short concentration time 9 14 min that fits the quick hydrological response observed in the field the debris flow mobilisation was not contemporaneous with the arrival of the peak water discharge in the initiation area probably due to the time required for the saturation of the highly conductive channel bed material channel cross section measurements taken along the flow channel indicate debris flow peak velocity and discharge ranging from 3 1 to 9 0 m s and from 23 to 71 m3 s respectively samples collected immediately after deposition were used to determine the water content and bulk density of the material channel scouring fines enrichment and transported volume increase testify erosion and entrainment of material along the flow channel field estimates of the rheological properties based on open channel flow of bingham fluid indicate a yield strength of 5000 400 pa and relatively low viscosity 60 326 pa s probably due to a high percentage of fines approx 30

spatial and temporal variation of sediment processes in the alpine semi arid basin of alkali creek colorado usa this paper develops a simple method of predicting sediment removal during snowmelt and flashfloods in alkali creek watershed western colorado the method links successful runoff simulations to field monitored sediment relationships to predict site yield the yield data are differenced to derive an index of scour and fill from which it is possible to infer the patterns of erosion and deposition that the stimulated events might produce across the watershed site sediment yield patterns produced suggest that even for a basin with this south facing orientation the summer storms are geomorphologically ineffective when compared to the amount of sediment transport potentially associated with the melt flows from a stimulated snowpack predicted patterns of scour and fill are spatially and temporally variable and are dependent on sediment supply laterally to the network scour is extensive at tributary junctions explaining the overall network concavity these patterns conform generally with monitored channel change in the network over a 13 year period and can be contrasted with patterns of sediment yield documented for other climatic types it is concluded that in this alpine semi arid environment the sediment rich debris removal associated with the decay of a considerable snowpack in the spring months is the most important geomorphic process and that tributary junctions appear likely to be the most active sites of change implications for threshold behaviour in these environments are also explored

stochastic forcing of sediment supply to channel networks from landsliding and debris flow sediment influx to channel networks is stochastically driven by rainstorms and other perturbations which are discrete in time and space and which occur on a landscape with its own spatial variability in topography colluvium properties and state of recovery from previous disturbances the resulting stochastic field of sediment supply interacts with the topology of the channel network and with transport processes to generate spatial and temporal patterns of flux and storage that characterize the sedimentation regime of a drainage basin the regime varies systematically with basin area we describe how the stochastic sediment supply is generated by climatic topographic geotechnical and biotic controls that vary between regions the general principle is illustrated through application to a landscape where sediment is supplied by mass wasting and the forcing variables are deterministic thickening of colluvium random sequences of root destroying wildfires and random sequences of rainstorms that trigger failure in a population of landslide source areas with spatial variance in topography and colluvium strength landslides stop in channels or convert to scouring debris flows depending on the nature of the low order channel network sediment accumulates within these channels for centuries before being transferred downstream by debris flows time series of sediment supply transport and storage vary with basin scale for any combination of climatic topographic and geotechnical controls in a companion paper benda and dunne this issue we use simulations of timing volumes and locations of mass wasting to study the interaction between a stochastically forced sediment supply and systematic changes of storage and flux through channel networks

alluvial cover dynamics in response to floods of various magnitudes the effect of the release of glaciogenic material in a swiss alpine catchment abstract fluvial incision into formerly glaciated landscapes is commonly affected by the release of glaciogenic sediments from the hillslopes via landsliding hillslope failure and debris flow activity these deposits typically comprise abundant block size clasts here we determine the ability of the fluvial processes to evacuate glacially derived sediments in an alpine hanging valley blanketed by 100 m thick glacial till we assess along stream profiles of basal shear stress during annual decadal and centennial floods by means of the hydrological model hec ras we use bed surface grain size data to i evaluate the shields stress profiles for these floods ii determine at which timescale the bed undergoes significant changes and to iii predict transport capacity patterns for each flood in addition we present digital photogrammetry based estimates of bed elevation changes over two selected time intervals that experienced low and high magnitude floods respectively the results indicate that floods with return periods of 10 years are capable of mobilizing the coarse fraction of the bed material thereby substantially altering the channel geometry the predicted near critical shields stress values for these floods in the area where the glacial deposits are thickest suggest a strong hillslope channel coupling which may have resulted in the formation of the knickzone observed in this sector however decadal to centennial floods are required to transport the material over long distances and scour the bed in the upper part of the inner gorge in addition the observed downstream trend from bed scouring to deposition in the inner gorge for these floods and the opposite trend for low magnitude floods suggest that these patterns are not directly controlled by downstream variations of transport capacity we propose that the supply of sediment through hillslope failure and bank collapse significantly contributes to the sediment flux for high magnitude floods we conclude that the morphology and the timescale of sediment transport in this glacially conditioned landscape have been substantially controlled by the hillslope derived supply of coarse grained material

dendrogeomorphic approaches for identifying the probable occurrence of debris flows and related torrential processes in steep headwater catchments the hrubý jesenik mountains czech republic abstract culminating parts of mid mountain ranges in central europe are interwoven by a network of high gradient streams these parts together with the surrounding slopes form a coupling system in which hazardous geomorphic processes such as landslides debris flows or flash floods can occur in the case of the hrub jesenik mountains eastern sudetes czech republic we present an evaluation of the debris flows and related torrential processes in the high gradient streams of the selected catchment based on dendrogeomorphic methods in addition to the classical dendrogeomorphic approaches we refined the procedure of identifying certain and probable events using new weighted indexes for event reconstruction additionally because of the steep narrow channels without a characteristic accumulation cone a new spatial approach is defined based on the spacing of disturbed trees for each event random distribution or clustering and location of disturbed trees in an individual section of the valley floor using kernel density analysis for each event and calculating the particular grids in arcgis software we are able to describe the spatial reach and probable nature of an event debris flow or hyperconcentrated flow dendrogeomorphic analysis of 397 sampled trees predominantly coniferous trees revealed 24 torrential events 15 certain nine probable since 1928 with peaks in 1991 1997 and 2010 according to index values in addition the spatial distribution of disturbed trees grouped in clusters in these years indicates debris flow events in the upper parts of the catchment it seems that new dendrogeomorphic approaches should be valuable in remote steep headwater catchments where several types of processes affect the valley floors

spatial and temporal variability of sediment delivery from alpine lake basins cathedral provincial park southern british columbia this paper presents reconstructions of holocene sediment yield from four alpine lakes in southern british columbia sediment yield is reconstructed on the basis of suites of dated and correlated cores from each lake facies analysis of the complete set of cores suggests that significant changes in sediment delivery have occurred during the holocene specifically a shift to a higher energy sedimentary environment in cooler wetter conditions in the late holocene estimated sediment yields range between 2 3 and 11 2 t km 2 a 1 maximum holocene variability is a 115 increase at one site highest variability is observed at sites just above treeline suggesting that reduced vegetation cover under cooler conditions is a key control on temporal variability of sediment yield at these sites the temporal variability observed at holocene timescales is within the range of natural spatial variability observed between the four closely spaced lakes overall the results suggest that the response of small catchments to climate change is highly contingent upon local catchment conditions and that at all but the most sensitive sites sediment yield changes associated with moderate climate warming are likely to be of a lesser magnitude than the natural spatial variability

initiation conditions for debris flows generated by runoff at chalk cliffs central colorado abstract we have monitored initiation conditions for six debris flows between may 2004 and july 2006 in a 0 3 km 2 drainage basin at chalk cliffs a band of hydrothermally altered quartz monzonite in central colorado debris flows were initiated by water runoff from colluvium and bedrock that entrained sediment from rills and channels with slopes ranging from about 14 to 45 the availability of channel material is essentially unlimited because of thick channel fill and refilling following debris flows by rock fall and dry ravel processes rainfall exceeding i 6 61 d 0 77 where i is rainfall intensity mm h and d is duration h was required for the initiation of debris flows in the drainage basin the approximate minimum runoff discharge from the surface of bedrock required to initiate debris flows in the channels was 0 15 m 3 s colluvium in the basin was unsaturated immediately prior to antecedent and during debris flows antecedent volumetric moisture levels in colluvium at depths of 1 cm and 29 cm ranged from 4 9 and 4 7 respectively during debris flows peak moisture levels in colluvium at depths of 1 cm and 29 cm ranged from 10 20 and 4 12 respectively channel sediment at a depth of 45 cm was unsaturated before and during debris flows antecedent moisture ranged from 20 22 and peak moisture ranged from 24 38 although we have no measurements from shallow rill or channel sediment we infer that it was unsaturated before debris flows and saturated by surface water runoff during debris flows our results allow us to make the following general statements with regard to debris flows generated by runoff in semi arid to arid mountainous regions 1 high antecedent moisture levels in hillslope and channel sediment are not required for the initiation of debris flows by runoff 2 locations of entrainment of sediment by successive runoff events can vary within a basin as a function of variations in the thickness of existing channel fill and the rate of replenishment of channel fill by rock fall and dry ravel processes following debris flows and 3 rainfall and simulated surface water discharge thresholds can be useful in understanding and predicting debris flows generated by runoff and sediment entrainment

long term consecutive dinsar for volume change estimation of land deformation in this paper the long term consecutive differential interferometric synthetic aperture radar sar technique is used to measure the volume change during land deformation this technique was used to investigate the subsidence of bandung city indonesia by assessing the data from two japanese l band spaceborne sars japanese earth resources satellite 1 sar and advanced land observation satellite phased array type l band synthetic aperture radar during the periods of 1993 1997 and 2007 2010 the results are confirmed using gps observation data ground survey data local statistics ground water level trend data and the geological formation of the study area the obtained results reveal a close correlation between the subsidence measurements and changes in the ground water level due to water pumping population growth industry growth and urbanization of the study area

initiation and runout characteristics of debris flow surges in ohya landslide scar japan abstract the characteristics of debris flows e g velocity discharge kinematic energy are highly dependent on surges incurring abrupt changes to flow height velocity and boulder concentration therefore understanding the initiation and runout characteristics of surges is essential when planning debris flow mitigation monitoring performed using 10 time lapse cameras tlcs in ohya landslide central japan where debris flows occur frequently due to mobilization of storage i e talus cone and channel deposits allowed us to obtain data on a series of surge processes from initiation to termination which occurred during each debris flow event we also analyzed temporal changes in the spatial distribution of storage in the debris flow initiation zone associated with sediment supply from hillslopes and evacuation of sediment by the occurrence of debris flows through periodic measurements of topography using unmanned aerial vehicles uavs debris flow surges were mainly induced by repetitive mass movement of storage through the erosion of channel deposits by overland flow sliding of channel deposits and sediment and water supply from channel banks and tributaries development of a spontaneous wave on the flow surface was not an important formation process of surges in the ohya landslide many debris flow surges initiated at channel sections with deep storage 2 m in depth located

the effects of artificial recharge of groundwater on controlling land subsidence and its influence on groundwater quality and aquifer energy storage in shanghai china long term groundwater overpumping in shanghai has caused serious land subsidence to restore the declined piezometric groundwater levels and to decrease the land subsidence rate artificial recharge ar of groundwater into confined aquifers through injected wells has been proposed as an important measurement since the beginning of the 1960s in the case of shanghai recharge source is tap water whose chemical constituents and temperature are different from groundwater consequently the issues of groundwater quality change and thermal energy are worthy of discussion in this paper we discussed the influences of ar for controlling land subsidence on 1 groundwater level and land subsidence rate 2 groundwater quality 3 aquifer thermal energy storage the results based on the collected long term historical data in the study area show that ar not only is beneficial to groundwater level rising and land rebound but also provides cheap energy sources for industrial production the groundwater quality presented the trend of desalination and a general increase in sulfate iron and manganese contents organic and nitrogenous compounds after the tap water injection however the ar s influence on groundwater quality was limited with the radius 100 m for single well recharge and 1000 m for well groups recharge to control the development of the land subsidence within a safe limit in the study area the injected confined aquifers and the distribution of the ar wells need to be further adjusted due to the limitation of current ar

colluvial sediment dynamics in mountain drainage basins abstract colluvial sediment dynamics are examined using a 70 year landslide inventory in formerly glaciated mountain drainage basins of coastal british columbia canada landslide sediment transfer is documented by identifying landslide types and by characterizing preferential sites of landslide initiation delivery and storage across spatial scales data analysis reveals that open slope landslides delivering material to seasonal or perennial channels and fluvial terraces are the dominant mechanisms of sediment transfer this finding suggests high instability of the low order channel network and its ongoing re organization degradation after generalized sediment recharge occurred in the last glacial maximum in the study period landslide activity across the landscape has generated net degradation on planar slopes and first order colluvial channels whereas unchannelled valleys higher order colluvial channels and alluvial channels have accumulated material the scaling relation of the landslide sediment yield appears to be controlled by the spatial arrangement of the relict glacial macro forms landslide yield is highest in unchannelled topography decreases at the scale of channel initiation ad 0 002 km2 and remains constant for drainage areas where length scales of cirque valley walls and hanging valley floors overlap 0 002

river loads and modern denudation of the alps a review this paper presents the first comprehensive analysis of sediment and dissolved load across an entire mountain range we investigate patterns and rates of modern denudation of the european alps based on a compilation of data about river loads and reservoir sedimentation from 202 drainage basins that are between ca 1 to 10 000 km2 large the study basins cover about 50 of the total area of the alps modern glaciated basins have the highest sediment yields of up to 7000 t km 2 a 1 which are on average 5 to 10 times higher than in non glaciated basins likewise sediment yield and glacial cover are positively correlated instead relief is a relatively weak predictor of sediment yield the strong glacial impact in the correlations is due to glacier recession since the 19th century as well as due to glacial conditioning during repeated quaternary glaciations which have produced the strong transient state of the alpine landscape we suggest that this is the major cause for ca 3 fold enhanced denudation of the western compared to the eastern alps chemical denudation rates are highest in the external alps dominated by carbonate sedimentary rocks where they make up about one third of total denudation the high rates cannot be explained without anhydrite dissolution we estimated that only 45 of the sediments mobilized in headwaters are exported out off the alps most sediments being trapped in artificial reservoirs the total amount of sediment annually trapped within the alps equates to 43 mt when corrected for sediment storage we obtain an area weighted mean total denudation rate for the alps of about 0 32 mm a 1 the pre dam rate might be as high as 0 42 mm a 1 in total ca 35 plus 23 mt of mass are exported each year out of the alps as solids and solutes respectively these rates are not enough to out pace modern rock uplift nevertheless pattern of sediment yield across the alps coincides roughly with the intensity of glacial conditioning and modern rock uplift supporting the hypothesis of an erosion driven uplift of the alps

debris flows some physical characteristics and behaviour field observations on 449 debris flows in the queen charlotte islands british columbia are summarized movement of debris is classified according to seven characteristic types designated for the purposes of the study data on the physical characteristics of the events are presented an analysis of the data is made with reference to event initiation yield and deposition using both mechanistic and morphological criteria for those events which initiate on an open slope the infinite slope model is used to establish a relationship between field drainage class and slope angle for assumed frictional and cohesive soil strength parameters the field drainage classes are directly related to the postulated location of the groundwater surface within the depth of the rupture plane deposition of channelized events is found to be influenced by the ratio of channel width to channel gradient with the onset of deposition expected when the ratio exceeds unity five classes of depositional area are proposed the mag

limits of sediment transfer in an alpine debris flow catchment illgraben switzerland abstract the 9 5 km 2 illgraben catchment located in the rhone valley in the central alps of switzerland is one of the most active debris flow torrents in the alps in this paper we present sediment yield data collected in 2006 for segments where hillslopes and channels form a fully connected network and contrast these with sediment yields measured for disconnected hillslopes the data reveal that sediment yields are 1 2 orders of magnitude larger in segments where hillslopes are connected with the channel network than on disconnected hillslopes support for this conclusion is provided by observations made on 1959 1999 and 2004 aerial photographs that the vegetation cover in the disconnected segments is still intact whereas denudation rates of several centimeters per year in the connected segments have inhibited the establishment of a stable vegetation cover furthermore sediment supplied from hillslopes during the past 40 years has temporarily accumulated along the illgraben channel indicating that the channel aggraded over this period and has not yet recovered an implication of this observation is that initiation of debris flows in the illgraben catchment is limited more by the availability of intense rainfall than sediment in contrast on disconnected hillslopes sediment flux does not appear to be driven by precipitation the petrographic composition of the illgraben fan deposits indicates two distinct sediment sources one related to rockfall and the other to landslides and debris flows the presence of clasts from both sources implies multiple processes of erosion deposition mixing and re entrainment in the catchment before the material is exported to the illgraben fan and to the rhone river in addition delivery of large amounts of coarse grained sediment to the rhone causes a modification of the flow pattern from meandering or anastomosing upstream to braided downstream hence the direct connectivity between hillslope and channelized processes in the illgraben catchment causes not only rapid topographic modifications in the catchment but also morphologic adjustment in the rhone valley downstream

rapid channel response to variability in sediment supply cutting and filling of the tarndale fan waipaoa catchment new zealand abstract in the headwaters of the waipaoa catchment fluvio mass movement gully complexes are currently significant contributors of sediment delivery of which is buffered by fans which have developed in the small tributaries that lead from the gully complexes biannual channel cross section surveys made since 1983 show seasonal aggradation incision cycles channels generally incise in summer and infill during the winter months this seasonal pattern of cutting and filling is driven by variations in sediment supply from the gully complexes in this paper to better understand patterns and processes of sediment delivery at the top of the sediment cascade we examine cut and fill cycles on the 11 ha tarndale fan over a two and a half year period analysis of sequential dems compiled from survey data obtained between december 2004 and august 2007 indicates cutting and filling may involve up to 47 000 tonnes of sediment over as little as three months during discrete severe rainstorm and or wet weather periods mass movements in the gully complex are enhanced and contribute large quantities of sediment to the fan via debris flows and landslides which infill channels during drier periods mass movement activity is inhibited and runoff incises the feeder channels

tectonic uplift threshold hillslopes and denudation rates in a developing mountain range studies across a broad range of drainage basins have established a positive correlation between mean slope gradient and denudation rates it has been suggested however that this relationship breaks down for catchments where slopes are at their threshold angle of stability because in such cases denudation is controlled by the rate of tectonic uplift through the rate of channel incision and frequency of slope failure this mechanism is evaluated for the san bernardino mountains california a nascent range that incorporates both threshold hillslopes and remnants of pre uplift topography concentrations of in situ produced cosmogenic 10 be in alluvial sediments are used to quantify catchment wide denudation rates and show a broadly linear relationship with mean slope gradient up to 30 above this value denudation rates vary substantially for similar mean slope gradients we propose that this decoupling in the slope gradient denudation rate relationship marks the emergence of threshold topography and coincides with the transition from transport limited to detachment limited denudation the survival in the san bernardino mountains of surfaces formed prior to uplift provides information on the topographic evolution of the range in particular the transition from slope gradient dependent rates of denudation to a regime where denudation rates are controlled by rates of tectonic uplift this type of transition may represent a general model for the denudational response to orogenic uplift and topographic evolution during the early stages of mountain building

the influence of landsliding on sediment supply and channel change in a steep mountain catchment abstract rates of sediment supply by landsliding to an alluvial channel in a small catchment in central switzerland were estimated over an 11 month study period fluvial sediment transport in the channel is independently monitored at the upstream and downstream ends of the study reach yielding a unique opportunity to quantitatively compare the volume of sediment supplied to the channel with the volume in fluvial transport landslide derived sediment discharge to the channel was greatest during the winter and spring months while most of the fluvial sediment transport occurred during short intense summer storms approximately 98 m 3 of sediment was delivered directly to the study reach by landsliding 80 m 3 was transported into the reach from upstream and 70 m 3 was transported out of the reach thus there was a net accumulation of 100 m 3 of sediment during the 11 month study decadal scale channel aggradation was independently assessed by comparing channel longitudinal profiles in 1993 and 2004 during this 11 year period a total of 1500 m 3 of sediment has accumulated in the study reach aggradation has occurred largely in two broad zones that correspond with both the locations of major landslide complexes and reaches of high channel slope indicating that hillslope sediment input left an imprint on the morphology of the channel bed that appears to be stable over at least decadal time scales

simulation of fully coupled finite element analysis of nonlinear hydraulic properties in land subsidence due to groundwater pumping a fully coupled mathematical model of land subsidence caused by groundwater pumping was established based on the mechanics of porous seepage and the theory of fluid solid interaction the mathematical model employing the galerkin finite element method was proposed to simulate the deformation dependencies of hydraulic properties due to the water pressure decrease in aquifers this model has been verified by comparing with the known analytical solutions in the confined aquifer results show that the simulated drawdown and displacements match well with those of analytical solutions to evaluate the nonlinear effects of hydraulic properties in the seepage and consolidation coupling phenomena the numerical model is applied to an ideal three layers numerical experiment the results show that the subsidence rate is faster than conventional groundwater theory when the nonlinear hydraulic properties nhp are considered in the coupled model the reason is that the water level decline due to groundwater withdrawal induces the soil compression and the porosity and permeability decrease decrease of permeability in regions adjacent to the pumping well produces hydraulic gradient and seepage forces that may result in accelerated subsidence therefore the effect of the nhp is an interaction process of pore water pressure and soil consolidation deformation and should not be ignored further studies of various hydrogeology problems are recommended to consider the heterogeneity concerning different stratigraphic condition in the field

an integrated method for rapid estimation of the valley incision by debris flows abstract valley incision by debris flow is an important process in creating and maintaining the topography of a valley in addition to explaining the significant growth of the magnitudes of debris flow hazards in this paper we introduce a semi empirical method to quantitatively estimate the valley incision process by debris flows over complex bed surface we first reproduce natural bed surface across the valley by a polyline and use a hydrograph of discharge versus time to represent the temporal variation of debris flow process the presented method subsequently predicts the debris flow behavior over an irregular bed surface a dynamic erosion law considers the solved debris flow behavior and estimates an instantaneous erosion rate finally the accumulative incision depth of bed sediment is calculated reshaping the initial bed surface across the valley the presented method is simple and therefore notably beneficial for practical work the performance of the proposed method has been tested using two case study applications results demonstrate that the presented method estimates comparable incision depth as revealed in the in situ survey and the numerical simulation

land subsidence characteristics of bandung basin as revealed by envisat asar and alos palsar interferometry abstract in this work land subsidence in bandung basin indonesia between 2002 and 2011 was mapped using the c band envisat asar and l band alos palsar data twenty four alos palsar and thirty envisat asar images acquired between 2002 2008 and 2007 2011 respectively were analysed several locations that were experiencing land displacement were identified including cimahi dayeuh kolot rancaekek solokan jeruk and gedebage the subsidence rates in the basin range from 240 mm year to 40 mm year the comparison between the alos palsar and envisat asar measurements which showed good agreement suggested the subsidence in many areas of the basin were steady between 2002 and 2011 except south bandung acceleration of subsidence in south bandung was observed between the measurements from the two datasets likely as a result of increasing population and industries the subsidence in the basin was expected mainly as a result of excessive groundwater extraction and soil consolidation caused by surficial loading gps survey data collected between 2002 and 2010 were used to validate the alos palsar and envisat asar measurements good correlations were observed between insar and gps measurements the comparison between the land subsidence measurements and the groundwater level information showed there were some correlations between them for every 1 m reduction in groundwater level per annum ground subsidence of 20 23 mm per annum has been observed the comparison results suggested that there was no evidence showing the aquifer in the basin is being recovered

the tectonic and metallogenic framework of myanmar a tethyan mineral system myanmar is perhaps one of the world s most prospective but least explored minerals jurisdictions containing important known deposits of tin tungsten copper gold zinc lead nickel silver jade and gemstones a scarcity of recent geological mapping available in published form coupled with an unfavourable political climate has resulted in the fact that although characterized by several world class deposits the nation s mineral resource sector is underdeveloped as well as representing a potential new search space for a range of commodities many of myanmar s known existing mineral deposits remain highly prospective myanmar lies at a crucial geologic juncture immediately south of the eastern himalayan syntaxis however it remains geologically enigmatic its mesozoic recent geological history is dominated by several orogenic events representing the closing of the tethys ocean we present new zircon u pb age data related to several styles of mineralization within myanmar we outline a tectonic model for myanmar from the late cretaceous onwards and document nine major mineralization styles representing a range of commodities found within the country we propose a metallogenetic model that places the genesis of many of these metallotects within the framework of the subduction and suturing of neo tethys and the subsequent himalayan orogeny temporal overlap of favourable conditions for the formation of particular deposit types during orogenic progression permits the genesis of differing metallotects during the same orogenic event we suggest the evolution of these favourable conditions and resulting genesis of much of myanmar s mineral deposits represents a single evolving mineral system the subduction and suturing of neo tethys

effects of human activity on erosion sedimentation and debris flow activity a case study of the qionghai lake watershed southeastern tibetan plateau china we report the results of a study of the qionghai lake watershed located on the southeastern edge of the qinghai tibetan plateau china designed to investigate the effects of human activity on changes in soil erosion intensity debris flow activity and lacustrine sedimentation the results indicate that the mean denudation rate of the watershed was about 0 82mm yr during the holocene however since 1952 the rate has increased to 1 82mm yr accompanied by a greatly increased sedimentation rate in qionghai lake the increased denudation rate was accompanied by increases in population and the related intensified exploitation of land resources including deforestation and an increase in the area of cultivated land in addition the increasing rate of denudation and lacustrine sedimentation is closely linked to the increased frequency of flooding and debris flows in the watershed based on our results we estimate that the longevity of qionghai lake is about 1200years in the case of natural evolution however this is reduced to 540years in the context of continued intensive human activity in the region these findings are important for the mitigation of mountain hazards such as debris flows and for the promotion of sustainable economic development in the qionghai lake area they also provide a basis for obtaining an improved estimate of changes in denudation rate on the southeastern edge of the qinghai tibet plateau

debris flow initiation and sediment recharge in gullies landslides that enter gullied low order drainages can either initiate debris flow or stop depositing sediment in the channel this process is one of the most common ways that debris flows initiate but little attention to date has been paid to evaluating the factors that affect whether or not the initial landslide will become a debris flow or deposit sediment in the channel statistically significant parameters that determine whether slope failures become debris flows or act to recharge in channel sediment are channel gradient angle of entry of failure into the channel initial failure volume and the amount of in channel stored sediment steeper channels low angles of entry lower volumes of in channel sediment and larger initial failures were more likely to result in debris flows this study found that as the volume of in channel stored sediment increased the volume of initial failure required to initiate a debris flow also increased this result calls into question the simple supply limited model of cyclical debris recharge and debris flow in low order gullied drainages and suggests a negative feedback mechanism between debris accumulation and debris flow susceptibility

sediment connectivity a framework for understanding sediment transfer at multiple scales a major challenge for geomorphologists is to scale up small magnitude processes to produce landscape form yet existing approaches have been found to be severely limited new ways to scale erosion and transfer of sediment are thus needed this paper evaluates the concept of sediment connectivity as a framework for understanding processes involved in sediment transfer across multiple scales we propose that the concept of sediment connectivity can be used to explain the connected transfer of sediment from a source to a sink in a catchment and movement of sediment between different zones within a catchment over hillslopes between hillslopes and channels and within channels using fluvial systems as an example we explore four scenarios of sediment connectivity which represent end members of behaviour from fully linked to fully unlinked hydrological and sediment connectivity sediment travel distance when combined with an entrainment parameter reflecting the frequency magnitude response of the system maps onto these end members providing a coherent conceptual model for the upscaling of erosion predictions this conceptual model could be readily expanded to other process domains to provide a more comprehensive underpinning of landscape evolution models thus further research on the controls and dynamics of travel distances under different modes of transport is fundamental copyright 2014 john wiley sons ltd

assessing entrainment of bed material in a debris flow event a theoretical approach incorporating monte carlo method entrainment of underlying bed sediment by a debris flow can significantly increase the debris flow magnitude to study this phenomenon a theoretical approach to assessing bed sediment entrainment is presented the approach is based on a static approximation that bed sediment entrainment occurs when the shearing stress of the flow is sufficiently high to overcome the basal resistance of the bed sediment in order to delineate erodible zones in a channel we analyze the critical condition of this static equilibrium model and subsequently propose a new concept of a critical line to detect the entrainment reaches in a channel considering the spatial and temporal uncertainties of the input parameter the approach is further incorporated within a monte carlo method and the distribution of entrainment zones and post entrainment volumes can be analyzed this approach is illustrated by back analysis of the 2010 yohutagawa debris flow event japan results from 10 000 trials of monte carlo simulation are compared with the in situ surveys it is shown that the present approach can be satisfactorily used to delineate erodible zones and estimate possible entrainment volume of the event discussion regarding the sensitivities and limitations of the approach concludes the paper copyright 2015 john wiley sons ltd

sediment transfer patterns at the illgraben catchment switzerland implications for the time scales of debris flow activities debris flows strongly control sediment transfer patterns in mountainous catchments we quantify sediment transfer at the illgraben switzerland where debris flows are frequent and geomorphic change is rapid four sequential aerial image series from fall 2007 to fall 2009 were used to measure landscape change in relation to debris flows the debris often originating from bedrock landslides was transported in patterns of erosion storage and remobilization the landslides typically stopped on the downslope hillslope or in the channel and they did not transform directly into debris flows the magnitude and nature of sediment transfer patterns show large spatial and temporal variability and the storage time of the deposits was shorter than one year landslide volumes were an order of magnitude smaller than the debris flows at the catchment outlet while the mechanism of debris flow initiation could not be determined unambiguously clearly debris flows must entrain substantial amounts of sediment along the flow path to attain the volumes estimated at the distal end of the fan

erosion under climate and human pressures an alpine lake sediment perspective we review the scientific efforts over the last decades to reconstruct erosion from continuous alpine lake sediment records we focused both on methodological issues showing the growing importance of non destructive high resolution approaches xrf core scanner as well as progresses in the understanding of processes leading to the creation of an erosion signal in lakes we distinguish continuous records from event records both provide complementary information but need to be studied with different approaches continuous regionally relevant records proved to be particularly pertinent to document regional erosion patterns throughout the holocene in particular applying the source to sink approach event based approaches demonstrated and took advantage of the strong non linearity of sediment transport in high altitude catchment areas this led to flood frequency and intensity reconstructions highlighting the influence of climate change upon flood dynamics in the mountain the combination of different record types both in terms of location high vs low elevation sedimentology high vs low terrigenous contribution and significance local vs regional is one of the main outputs of this paper it allows the establishment of comprehensive histories of nw french alps erosion but also and consequently soil dynamics and hydrological patterns throughout the holocene we also discuss the influence of glacier dynamics one of the major agents of erosion in the alps a major feature is the growing human influence upon erosion at a local scale since at least the middle of the bronze age 3500 cal bp however and according to the regional record from lake bourget only few periods of rising erosion at local scales generated a regional record that can be discriminated from wetter climatic periods among them the period between 200 bce and 400 ad appeared to be marked by a generalised rise in human triggered erosion at local scales in the northern french alps this review highlights the importance of modern high resolution and interdisciplinary studies of lake sediments in order to better understand the complex relationships between humans climate and the earth system in general we strongly argue that regional integration of data is now required to move a step further such an integration is easier with cost and time effective methods as well as after a better definition of approaches and their limits this should lead to a stronger collaboration between paleo data producers and modellers in the near future

conditions for generation of fire related debris flows capulin canyon new mexico comparisonoftheresponsesofthreedrainagebasinsburnedbythedomefireof1996innewmexicoisusedtoidentifythe hillslope channelandfirecharacteristicsthatindicateasusceptibilityspecificallytowildfire relateddebrisflow summer thunderstorms generated three distinct erosive responses from each of three basins the capulin canyon basin showed widespreaderosivesheetwashandrillingfromhillslopes andseverefloodingoccurredinthechannel thenorthtributary basin exhibited extensive erosion of the mineral soil to a depth of 5 cm and downslope movement of up to boulder sized material andatleastonedebrisflowoccurredinthechannel negligiblesurfacerunoffwasobservedinthesouthtributary basin thenegligiblesurfacerunoffobservedinthesouthtributarybasinisattributedtothelimitedextent andseverityof the fire in that basin the factors that best distinguish between debris flow producing and flood producing drainages are drainage basin morphology and lithology a rugged drainage basin morphology an average 12 per cent channel gradient andsteep roughhillslopescoupledwithcolluviumandsoilweatheredfromvolcaniclasticandvolcanicrockspromotedthe generation of debris flows a less rugged basin morphology an average gradient of 5 per cent and long smooth slopes mantled with pumice promoted flooding flood and debris flow responses were produced without the presence of waterrepellentsoils thecontinuityandseverityoftheburnmosaic theconditionoftheriparianvegetation theconditionofthe fibrous root mat accumulations of dry ravel and colluvial material in the channel and on hillslopes and past debris flow activity appearedtohavelittlebearingonthedistinctiveresponsesofthebasins publishedin2000byjohnwiley sons ltd

patterns and controls of sediment production transfer and yield in the illgraben quantification of the volumes of sediment removed by rock slope failure and debris flows and identification of their coupling and controls are pertinent to understanding mountain basin sediment yield and landscape evolution this study captures a multi decadal period of hillslope erosion and channel change following an extreme rock avalanche in 1961 in the illgraben a catchment prone to debris flows in the swiss alps we analyzed photogrammetrically derived datasets of hillslope and channel erosion and deposition along with climatic and seismic variables for a 43 year period from 1963 to 2005 based on these analyses we identify and discuss 1 patterns of hillslope production channel transfer and catchment sediment yield 2 their dominant interactions with climatic and seismic variables and 3 the nature of hillslope channel coupling and implications for sediment yield and landscape evolution in this mountain basin our results show an increase in the mean hillslope erosion rate in the 1980s from 0 24 0 01 m yr 1 to 0 42 0 03 m yr 1 that coincided with a significant increase in air temperature and decrease in snow cover depth and duration which we presume led to an increase in the exposure of the slopes to thermal weathering processes the combination of highly fractured slopes close to the threshold angle for failure and multiple potential triggering mechanisms means that it is difficult to identify an individual control on slope failure on the other hand the rate of channel change was strongly related to variables influencing runoff a period of particularly high channel erosion rate of 0 74 0 02 m yr 1 1992 1998 coincided with an increase in the frequency and magnitude of intense rainfall events hillslope erosion exceeded channel erosion on average indicative of a downslope directed coupling relationship between hillslope and channel and demonstrating the first order control of rock slope failure on catchment sediment yield and landscape evolution

a combined study of radar facies lithofacies and three dimensional architecture of an alpine alluvial fan illgraben fan switzerland alluvial fans serve as useful archives that record the history of depositional and erosional processes in mountainous regions and thus can reveal the environmental controls that influenced their development economically they play an important role as groundwater reservoirs as well as host rocks for hydrocarbons in deeply buried systems the interpretation of these archives and the evaluation of their reservoir architecture however are problematic because marked heterogeneity in the distribution of sedimentary facies makes correlation difficult this problem is compounded because the accumulated sedimentary deposits of modern unconsolidated fan systems tend to be poorly exposed and few such systems have been the focus of investigation using high resolution subsurface analytical techniques to overcome this limitation of standard outcrop analogue studies a geophysical survey of an alpine alluvial fan was performed using ground penetrating radar to devise a scaled three dimensional subsurface model radar facies were classified and calibrated to lithofacies within a fan system that provided outcropping walls and these were used to derive a three dimensional model of the sedimentary architecture and identify evolutionary fan stages the illgraben fan in the swiss alps was selected as a case study and a network of ca 60 km sections of ground penetrating radar was surveyed seven radar facies types could be distinguished which were grouped into debris flow deposits and stream flow deposits assemblages of these radar facies types show three depositional units which are separated by continuous fan wide reflectors they were interpreted as palaeo surfaces corresponding to episodes of sediment starvation that affected the entire fan an overall upward decline in the proportion of debris flow deposits from ca 50 to 15 and a corresponding increase in stream flow deposits were identified the uppermost depositional unit is bounded at its base by a significant incision surface up to 700 m wide which was subsequently filled up mostly by stream flow deposits the pronounced palaeo surfaces and depositional trends suggest that allocyclic controls governed the evolution of the illgraben fan making this fan a valuable archive from which to reconstruct past sediment fluxes and environmental change in the alps the results of the integrated outcrop geophysical approach encourage similar future studies on fans to retrieve their depositional history as well as their potential reservoir properties

the influence of debris flows on channels and valley floors in the oregon coast range u s a debris flows are one of the most important processes which influence the morphology of channels and valley floors in the oregon coast range debris flows that initiate in bedrock hollows at heads of first order basins erode the long accumulated sediment and organic debris from the floors of headwater first and second order channels this material is deposited on valley floors in the form of fans levees and terraces in channels deposits of debris flows control the distribution of boulders the stochastic nature of sediment supply to alluvial channels by debris flows promotes cycling between channel aggradation which results in a gravel bed morphology and channel degradation which results in a mixed bedrock and boulder bed morphology temporal and spatial variability of channel bed morphology is expected in other landscapes where debris flows are an important process

stochastic forcing of sediment routing and storage in channel networks the stochastic field of sediment supply to the channel network of a drainage basin depends on the large scale interactions among climatically driven processes such as forest fire and rainstorms topography channel network topology and basin scale during infrequent periods of intense erosion large volumes of colluvium are concentrated in parts of a channel network particularly near tributary junctions the rivers carry bed material and wash load downstream from these storage sites at different rates the bed material travels slowly creating transient patterns of sediment transport sediment storage and channel morphology along the channel network as the concentrations of bed material migrate along the network their waveforms can undergo changes by diffusion interference at tributary junctions and loss of mass through temporary sediment storage in fans and terraces and through particle abrasion which converts bed material to wash load we investigated how these processes might influence the sediment mass balance in channels of third and higher order in a 215 km 2 drainage basin within the oregon coast range over a simulated 3000 year period with a climate typical of the late holocene we used field measurements and a simulation model to illustrate interactions between the major controls on large scale processes functioning over long periods of time in complex drainage basins

interplate coupling model off the southwestern coast of java indonesia based on continuous gps data in 2008 2010 abstract we present an interplate coupling model of the australia java plate interface off the southwestern coast of java indonesia based on data from the indonesian permanent gps station network from 2008 to 2010 the majority of vertical data indicate uplift while the baseline change rate indicates coastal contraction in the middle of the network and coastal extension in the eastern part of the network using the rate of baseline length changes and the absolute rate of vertical displacements we apply a geodetic inversion method by yabuki and matsu ura 1992 from the inversion result we interpret the main source of the observed velocity in west java as resulting from contributions of 1 interplate coupling off ujung kulon pelabuhan ratu at 20 to 40 km depth with a slip rate range from 48 to 56 mm yr 2 interplate coupling off pangandaran at 37 to 45 km depth with a slip rate of 48 to 55 mm yr 3 afterslip off pangandaran within the rupture area of the 2006 m7 8 java earthquake in the depth range of 15 20 km with a slip excess rate of 57 61 mm yr the absence of a megathrust earthquake for at least 300 years in this region implies seismic moment accumulation during this time period of 1 6 10 21 nm mw 8 7 off ujung kulon pelabuhan ratu and 3 9 10 21 nm mw 8 3 off pangandaran unless episodic slow slips release tectonic stress