integrated hazard assessment of cirenmaco glacial lake in zhangzangbo valley central himalayas abstract glacial lake outburst floods glofs have recently become one of the primary natural hazards in the himalayas there is therefore an urgent need to assess glof hazards in the region cirenmaco a moraine dammed lake located in the upstream portion of zhangzangbo valley central himalayas has received public attention after its damaging 1981 outburst flood here by combining remote sensing methods bathymetric survey and 2d hydraulic modeling we assessed the hazard posed by cirenmaco in its current status inter annual variation of cirenmaco lake area indicates a rapid lake expansion from 0 10 0 08 km2 in 1988 to 0 39 0 04 km2 in 2013 bathymetric survey shows the maximum water depth of the lake in 2012 was 115 2 m and the lake volume was calculated to be 1 8 107 m3 field geomorphic analysis shows that cirenmaco glacial lake is prone to glofs as mass movements and ice and snow avalanches can impact the lake and the melting of the dead ice in the moraine can lower the dam level hec ras 2d model was then used to simulate moraine dam failure of the cirenmaco and assess glof impacts downstream reconstruction of cirenmaco 1981 glof shows that hec ras can produce reasonable flood extent and water depth thus demonstrate its ability to effectively model complex glofs glof modeling results presented can be used as a basis for the implementation of disaster prevention and mitigation measures as a case study this work shows how we can integrate different methods to glof hazard assessment

tidal distortion caused by the resonance of sexta diurnal tides in a micromesotidal embayment double high water and double peak flood current were observed in daya bay dyb china which is a shallow mixed mainly semidiurnal tide dominated bay with a micro to meso tidal range harmonic analysis reveals that the quarter and especially the sexta diurnal constituents are getting much stronger as tides propagating into the bay the astronomical tides induced tidal asymmetry is yet dominant at the bay entrance but overtaken by the sexta diurnal tides at the end of the bay both the m4 and m6 tide meet the requirement proposed in previous studies but still unable to produce a double high water alone therefore the conditions to produce a double high water between a fundamental tide and its higher harmonics need to be revisited analytical solutions were obtained in this paper which fit the numerical solutions very well modelling result indicates m6 alone with m2 can produce the double high water in dyb but limited in some regions while the combination of m2 m4 and m6 tides would enhance the capability the amplification of sexta diurnal tides in dyb is dominated by resonance and followed by shoaling effect bottom friction damped m6 a lot and largely confined its amplification however the quadratic friction and other nonlinear processes are just responsible for about 10 of the total m6 increase this article is protected by copyright all rights reserved

simple shear testing of sensitive very soft offshore clay for wide strain range stiffness and damping properties of sensitive very soft clay sediments of the italian adriatic continental shelf are determined by means of two series of cyclic simple shear tests one with 12 stages and one with two stages the apparatus used in this research is capable of investigating the stress strain behaviour of the soil in a wide range of shear strains from about 0 0004 to 1 test results were expressed in terms of small strain shear modulus g0 normalized equivalent shear modulus geq g0 and damping ratio d versus cyclic shear strain amplitude c these parameters were analyzed in the framework of existing literature by comparison with empirical correlations developed for onshore materials of different plasticity and limited to g0 also for soft soils the dependence of g0 geq g0 c and d c on factors such as void ratio stress history and loading cycles is analyzed and discussed

the use of one and two dimensional hydraulic modelling to reconstruct a glacial outburst flood in a steep alpine valley the hydrologic characteristics of the 1943 outburst flood from the glacier du mont mine switzerland are herein reconstructed using field evidence palaeostage indicators in conjunction with shallow water modelling techniques these techniques rely on accurately characterising the hydraulic roughness of the channel the water height established as boundary conditions and the main flow path during the former flood but the selection of appropriate parameter values can be problematic and hence there is uncertainty in the estimated discharge in this study minimal flow discharge estimates derived from one dimensional modelling were found to vary between 429 and 557 m3 s 1 as the hydraulic roughness ks and water height at the inlet were varied over a realistic range of values 0 8 1 4 m and 3 31 6 m respectively whereas flow rates derived via two dimensional modelling were confined in a narrower lower range of 358 454 m3 s 1 this degree of sensitivity to bed roughness ks boundary conditions and the spatial dimensions of the modelling approach is for the one dimensional modelling higher than reported in previous studies but the precision of flow discharge values reconstructed using the two dimensional modelling approach appears to be acceptable even for floods in the very steep valley 0 1 m m that is subject of this study

an assessment procedure for glacial hazards in the swiss alps glacial hazards such as ice avalanches glacial lake outburst floods and debris flows have caused severe damage in populated mountain regions such as the swiss alps assessment of such hazards mus

effects of confining stress density and initial static shear stress on the cyclic shear response of fine grained unclassified tailings a constant volume direct simple shear apparatus was used to investigate the effects of confining stress initial static shear stress and void ratio on the liquefaction resistance of fine grained tailings the cyclic resistance ratio also expressed as the overburden stress correction factor was found to decrease with increasing confining stresses in the range 100 400 kpa and to gradually increase from 400 kpa onwards when samples were tested at the same initial void ratio the presence of an initial static shear stress decreased the liquefaction resistance a key outcome of the work was to reveal the critical importance of density on liquefaction susceptibility of compressible tailings thus a combined correction factor to account for overburden stress and density on cyclic resistance was proposed

impact of desiccation on monotonic and cyclic shear strength of thickened gold tailings abstractvarious forms of thickened or high density tailings characterized by exhibition of a yield stress that facilitates deposition in gently sloped stacks are increasingly used for a variety of mining operations although this technology reduces reliance on containment by dams and the associated risk of catastrophic failure regulators are concerned with remobilization of such unbounded deposits by earthquakes or extreme rainfalls therefore the monotonic and cyclic shear strength of thickened tailings layers are of significant interest thickened tailings experience a particular stress history during deposition which may include desiccation rewetting and subsequent consolidation by burial under new tailings the effect of this stress history on their shear response is investigated using a norwegian geotechnical institute ngi type simple shear device samples are alternately mechanically overconsolidated or subjected to desiccation and subsequent rewetting because of burial by fresh tailings be

the formation and failure of natural dams of the numerous kinds of dams that form by natural processes dams formed from landslides glacial ice and late neoglacial moraines present the greatest threat to people and property landslide dams form in a wide range of physiographic settings the most common types of mass movements that form landslide dams are rock and debris avalanches rock and soil slumps and slides and mud debris and earth flows the most common initiation mechanisms for dam forming landslides are excessive rainfall and snowmelt and earthquakes landslide dams can be classified into six categories based on their relation with the valley floor type i dams 11 of 184 landslide dams from around the world that we were able to classify do not reach from one valley side to the other type ii dams 44 span the entire valley floor in some cases depositing material high on opposite valley sides type iii dams 41 move considerable distances both upstream and downstream from the landslide failure type iv dams 1 are rare and involve the contemporaneous failure of material from both sides of a valley type v dams 1 also are rare and are created when a single landslide sends multiple tongues of debris into a valley and forms two or more landslide dams in the same reach of river type vi dams 3 involve one or more failure surfaces that extend under the stream or valley and emerge on the opposite valley side many landslide dams fail shortly after formation in our sample of 73 documented landslide dam failures 27 of the landslide dams failed less than 1 day after formation and about 50 failed within 10 days over topping is by far the most common cause of failure the timing of failure and the magnitude of the resulting floods are controlled by dam size and geometry material characteristics of the blockage rate of inflow to the impoundment size and depth of the impoundment bedrock control of flow and engineering controls such as artificial spill ways diversions tunnels and planned breaching by blasting or conventional excavation glacial ice dams can produce at least nine kinds of ice dammed lakes the most dangerous are lakes formed in main valleys dammed by tributary glaciers failure can occur by erosion of a drainage tunnel under or through the ice dam or by a channel over the ice dam cold polar ice dams generally drain supraglacially or marginally by downmelting of an outlet channel warmer temperate ice dams tend to fail by sudden englacial or subglacial breaching and drainage late neoglacial moraine dammed lakes are located in steep mountain areas affected by the advances and retreats of valley glaciers in the last several centuries these late neoglacial dams pose hazards because 1 they are sufficiently young that vegetation has not stabilized their slopes 2 many dam faces are steeper than the angle of repose 3 these dams and lakes are immediately downslope from steep crevassed glaciers and near vertical rock slopes and 4 downstream from these dams are steep canyons with easily erodible materials that can be incorporated in the flow and increase flood peaks the most common reported failure mechanism is overtopping and breaching by a wave or series of waves in the lake generated by icefalls rockfalls or snow or rock avalanches melting of ice cores or frozen ground and piping and seepage are other possible failure mechanisms natural dams may cause upstream flooding as the lake rises and downstream flooding as a result of failure of the dam although data are few for the same potential energy at the dam site ownstream flood peaks from the failure of glacier ice dams are smaller than those from landslide moraine and structed earth fill and rock fill dam failures moraine dam failures appear to produce some of the largest downstream flood peaks for potential energy at the dam site greater than 1011 1012 joules differences in flood peaks natural dam failures appear to be controlled by dam characteristics and failure mechanisms

effects of fines content on liquefaction strength and dynamic settlement of reclaimed soil in this study the reclaimed soils in the yunlin area of west taiwan are adopted as test samples the specimens were prepared by moist tamping at different relative densities and fines contents triaxial liquefaction tests were performed to evaluate the liquefaction strength and liquefaction induced settlement the test results show that the liquefaction strength of reclaimed soil increases as the relative density increases in addition under constant relative density the liquefaction strength decreases as the fines content increases based on the test results and one dimensional consolidation theory the volumetric strain and settlement can be evaluated by dry density and fines content of the reclaimed soil the results show that the settlement ratio decreases as the relative density increases the figures and results can be references for the evaluation of liquefaction strength and liquefaction induced settlement the results are useful for liquefaction strength and settlement analysis for planning d

response of normally consolidated kaolin clay under irregular cyclic loading and comparison with predictions from the accumulation procedure the accumulation procedure on contour diagrams of shear strain is used in geotechnical design to account for the effect of cyclic loading on offshore foundations in this paper contour diagrams of

liquefaction testing of stratified silty sands the cyclic behavior of stratified silty sandy soils is at present poorly understood yet these materials are commonly found in alluvial deposits and hydraulic fill which have a history of liquefaction during earthquakes the main objective of this research project was to compare the behavior of stratified and homogeneous silty sands during seismic liquefaction conditions for various silt contents and confining pressures a comprehensive experimental program was undertaken in which a total of 150 stress controlled undrained cyclic triaxial tests were performed two methods of sample preparation were used for each soil type these methods included moist tamping representing uniform soil conditions and sedimentation representing layered soil conditions the silt contents ranged from 10 to 50 and confining pressures in the range of 50 to 250 kpa were considered the results indicated that the liquefaction resistances of layered and uniform soils are not significantly different despite the fact that th

shear and dewatering behaviour of densified gold tailings in a laboratory simulation of multi layer deposition tailings may undergo desiccation stress history under varied climatic and depositional parameters while tailings substantially dewatered prior to deposition may experience desiccation under the gr

an improved method to represent dem uncertainty in glacial lake outburst flood propagation using stochastic simulations modelling glacial lake outburst floods glofs or jokulhlaups necessarily involves the propagation of large and often stochastic uncertainties throughout the source to impact process chain since flood routing is primarily a function of underlying topography communication of digital elevation model dem uncertainty should accompany such modelling efforts here a new stochastic first pass assessment technique was evaluated against an existing gis based model and an existing 1d hydrodynamic model using three dems with different spatial resolution the analysis revealed the effect of dem uncertainty and model choice on several flood parameters and on the prediction of socio economic impacts our new model which we call mc lcp monte carlo least cost path and which is distributed in the supplementary information demonstrated enhanced stability when compared to the two existing methods and this stability was independent of dem choice the mc lcp model outputs an uncertainty continuum within its extent from which relative socio economic risk can be evaluated in a comparison of all dem and model combinations the shuttle radar topography mission srtm dem exhibited fewer artefacts compared to those with the advanced spaceborne thermal emission and reflection radiometer global digital elevation model aster gdem and were comparable to those with a finer resolution advanced land observing satellite panchromatic remote sensing instrument for stereo mapping alos prism derived dem overall we contend that the variability we find between flood routing model results suggests that consideration of dem uncertainty and pre processing methods is important when assessing flow routing and when evaluating potential socio economic implications of a glof event incorporation of a stochastic variable provides an illustration of uncertainty that is important when modelling and communicating assessments of an inherently complex process

comparison of truly undrained and constant volume direct simple shear tests the paper describes a chamber for the norwegian geotechnical institute s direct simple shear device that enables undrained tests with pore pressure measurements to be run the results of undrained

mechanism for postliquefaction water film generation in layered sand soil investigations at two sites demonstrate that layered structure or stratification in sand deposits is prevalent not only in reclaimed ground but also in natural alluvial ground one dimensional liquefaction tests in a lucite tube are then carried out for models of several types of layered sand indicating that water films will develop under most circumstances beneath or within less permeable sublayers a basic mechanism for the water film generation is discussed based on the measurements of soil settlement and excess pore pressure the development of the water film and the associated soil settlement are numerically simulated by a simple sedimentation analysis and a rational explanation of the test results is found thus a significant involvement of water films in liquefied sand deposits and their basic mechanism are clarified it is highly probable that water films are involved as a part of a sliding surface and play a significant role in a seismically induced flow failure in loose and layered sand deposits during liquefaction

cyclic behaviour of reconstituted and desiccated rewet thickened gold tailings in simple shear a simple shear apparatus norwegian geotechnical institute ngi type has been used to investigate the mechanical behaviour of gold tailings under monotonic cyclic and post cyclic loading specimens were prepared either by reconstituting the tailings at different water contents or by employing a dry wet preparation technique the latter technique attempted to simulate a realistic stress history for thickened tailings deposition by preparing the specimen at the pumping water content and subsequently allowing it to settle and then desiccate to a target water content subsequently these specimens are rewetted and then consolidated cyclic resistance ratios for specimens prepared by the dry wet preparation technique were considerably higher than those of specimens prepared by the standard technique though there appears to be no advantage in drying the tailings past the shrinkage limit in general the tailings could experience significant deformation during cyclic and post cyclic loading irrespective

cyclic loading response of loose air pluviated fraser river sand for validation of numerical models simulating centrifuge tests cyclic loading response of loose fraser river sand was investigated as input to numerical simulation of centrifuge physical models using constant volume direct simple shear tests conducted with a

cyclic shear response of fine grained mine tailings the mechanical response of three different types of fine grained mine tailings is examined using data from constant volume cyclic direct simple shear dss tests under cyclic dss loading fine grained tailings typically exhibit a cumulative decrease in effective stress along with progressive degradation of shear stiffness the observed shear strain development due to cyclic mobility is similar in form to that of the previously observed cyclic shear response for natural silts the cyclic resistance ratio crr of laterite tailings is observed to increase with an increase in the initial effective confining stress vc for this material the dilative tendency due to stress densification seems to have overridden the contractive tendency due to the increase in confining stress in contrast the crr of copper gold zinc tailings is insensitive to the initial effective confining stress suggesting a response similar to that of normally consolidated clay the postcyclic maximum shear strength ratio su pc v

flow of variably fluidized granular masses across three dimensional terrain 1 coulomb mixture theory rock avalanches debris flows and related phenomena consist of grain fluid mixtures that move across three dimensional terrain in all these phenomena the same basic forces govern motion but differing mixture compositions initial conditions and boundary conditions yield varied dynamics and deposits to predict motion of diverse grain fluid masses from initiation to deposition we develop a depth averaged three dimensional mathematical model that accounts explicitly for solid and fluid phase forces and interactions model input consists of initial conditions path topography basal and internal friction angles of solid grains viscosity of pore fluid mixture density and a mixture diffusivity that controls pore pressure dissipation because these properties are constrained by independent measurements the model requires little or no calibration and yields readily testable predictions in the limit of vanishing coulomb friction due to persistent high fluid pressure the model equations describe motion of viscous floods and in the limit of vanishing fluid stress they describe one phase granular avalanches analysis of intermediate phenomena such as debris flows and pyroclastic flows requires use of the full mixture equations which can simulate interaction of high friction surge fronts with more fluid debris that follows special numerical methods described in the companion paper are necessary to solve the full equations but exact analytical solutions of simplified equations provide critical insight an analytical solution for translational motion of a coulomb mixture accelerating from rest and descending a uniform slope demonstrates that steady flow can occur only asymptotically a solution for the asymptotic limit of steady flow in a rectangular channel explains why shear may be concentrated in narrow marginal bands that border a plug of translating debris solutions for static equilibrium of source areas describe conditions of incipient slope instability and other static solutions show that nonuniform distributions of pore fluid pressure produce bluntly tapered vertical profiles at the margins of deposits simplified equations and solutions may apply in additional situations identified by a scaling analysis assessment of dimensionless scaling parameters also reveals that miniature laboratory experiments poorly simulate the dynamics of full scale flows in which fluid effects are significant therefore large geophysical flows can exhibit dynamics not evident at laboratory scales

freshwater megaflood sedimentation what can we learn about generic processes abstract there is growing recognition that sedimentary deposits related to high energy large scale freshwater floods are widespread across the continents and in the main can be related to quaternary outbreak flows from ice dammed lakes such deposits may also occur in the neogene and earlier recognition of these megaflood deposits is hindered by the lack of well conditioned stratigraphic models of depositional successions however descriptions of successions from many locations often exhibit commonalities when compared carefully thus the primary purpose of this paper is to examine and condense the published stratigraphic and sedimentological evidence so as to identify the key signatures of megaflood successions the deposits often are the only record of a flood and so the secondary purpose is to interpret the sedimentary sequences in order to recreate the behaviour of floods through single and multiple events finally some pointers are provided as to those areas of sedimentological research that might be profitably explored in more depth to improve understanding of megaflood dynamics a key characteristic of megaflood deposits is the apparent massive appearance of single units which on closer inspection usually are amalgamated layers of similar grain size distribution individual beds and sets of beds are commonly near horizontal planar and laterally extensive successions evidently are not channelized and extensivity is indicative of simultaneous and coherent deposition over large areas localised large scale clinoforms or smaller scale cross beds are common associated with bar front or dune progradation respectively but otherwise extensivity implies that cross cutting erosional contacts notably steeply inclined examples and small scale scours are not common except immediately around large isolated clasts such as dropstones and ice blocks a common vertical stack of sequences in any one succession consists of 1 basal thick coarse parallel bedded units 2 large scale clinoforms 3 horizontally bedded thin laminated units 4 ripple and dune cross beds 5 silt beds and 6 succession capping debris flow deposits in some cases such a succession usually is indicative of a single cycle of waxing and waning flood flow generally dominated by high concentration suspension deposition onto plane beds the high power allows the transport of fine gravel and coarse sand in suspension leading upon deposition to relatively coarse beds from suspension fall out clay and silt is generally sparse or absent being transported further down the system at the scale of the hydrograph the successions indicate that flows initially accelerate and then decelerate with significant shorter period flow pulses also evident in the sedimentary signatures in parallel bedded sequences primarily during waxing flows bedload transport often was ineffective in sorting sediment due to the high rates of deposition from the highly sediment charged waters resulting in diffuse accretion surfaces at each location similar sequence stacks are common leading to the impression of rhythmic deposition from pulsing flow including from repetitive series of floods although often composed of coarse grains many sequence stacks excluding any debris flows are not dissimilar to turbidity flow sequences the bouma sequence in particular although there is limited experimental evidence for turbidity currents associated with high energy freshwater flows theory does not preclude the deposition of similar sedimentary motifs from high concentration flows such that an analogy between some megaflood sedimentary beds and turbidites is not unreasonable despite considerable variation in megaflood sedimentary successions commonalities occur which are indicative of similar processes of deposition from high energy floods at geographically different locations the changes in style of deposition throughout a succession provide clues as to the nature of the flood flows and this information could be used to improve estimates of flood hydrograph behaviour however hypotheses linking deposit characteristics to flow dynamics are currently ill conditioned and often poorly tested the majority of published studies describe the coarser scale stratigraphy with only passing reference to the fine scale structure of individual beds closer attention to lamination styles particle orientation and syn depositional deformation structures for example should provide information on the flow mechanics at the time of bed deposition thus better consideration of the sedimentology of megaflood deposit beds will lead to better understanding of the controlling hydraulics and should result in better models of flood deposition

reconstructing historic glacial lake outburst floods through numerical modelling and geomorphological assessment extreme events in the himalaya westoby m j glasser n f hambrey m j brasington j reynolds j m hassan m a a m 2014 reconstructing historic glacial lake outburst floods through numerical modelling and geomorphological assessment extreme events in the himalaya earth surface processes and landforms 39 12 1675 1692

active tectonics in eastern lunana nw bhutan implications for the seismic and glacial hazard potential of the bhutan himalaya 1 paleoseismological investigations brittle fault analysis and paleostrain calculations combined with the interpretation of satellite imagery and flood wave modeling were used to investigate the seismic and associated glacial hazard potential in eastern lunana a remote area in nw bhutan seismically induced liquefaction features cracked pebbles and a surface rupture of about 6 8 km length constrain the occurrence of m 6 earthquakes within this high altitude periglacial environment which are the strongest earthquakes ever been reported for the kingdom of bhutan seismicity occurs along conjugate sets of faults trending ne sw to nnw sse by strike slip and normal faulting mechanism indicating e w extension and n s shortening the strain field for these conjugate sets of active faults is consistent with widespread observations of young e w expansion throughout southern tibet and the north himalaya we expect however that n s trending active strike slip faults may even reach much farther to the south at least into southern bhutan numerous glacial lakes exist in the investigation area and today more than 100 106 m3 of water are stored in moraine dammed and supraglacial lakes which are crosscut by active faults strong earthquakes may trigger glacial lake outburst floods and the impact of such flash floods may be worst 80 km downstream where the valley is broad and densely populated consequently tectonic models of active deformation have to be closely linked with glacial hazard evaluation and require rethinking and modification

static and dynamic properties of a lightly cemented silicate grouted sand this paper describes the results of an experimental investigation on the behaviour of a lightly grouted loose medium sand under both monotonic and cyclic loading the experimental programme in the present study was carried out on both untreated and treated sand specimens stabilized with a silica based grout and comprises isotropic triaxial compression tests equipped with bender elements drained triaxial monotonic shearing tests and undrained cyclic tests in a simple shear ss apparatus the results highlight that the weak cementation level induced by chemical treatment was sufficient to moderately increase small strain stiffness and stress dilatancy of the grouted sand during drained monotonic shear a small cohesion intercept was observed in the analyzed failure envelope while cyclic liquefaction resistance exhibited a much more significant increase with a different pattern of behaviour between low and high stress levels finally undrained cyclic ss test results evidenced that silicate grout emplo

laboratory analysis of mudflow properties a rotational viscometer has been designed for laboratory measurements of the rheological properties of natural mudflow deposits in colorado the mudflow matrices comprised of silt and clay particles are sheared under temperature controlled conditions at volumetric sediment concentrations ranging from 0 10 0 45 this study stresses the importance of conducting rheological measurements at low rates of shear because 1 those are the conditions found in natural channels and 2 they avoid the slippage problems observed at large sediment concentrations at low rates of shear the bingham model is fitted to the measured rheograms and both the viscosity and yield stress increase exponentially with the sediment concentration of the fluid matrix both the yield stress and the viscosity increase by three orders of magnitude as the volumetric concentration of sediments in the fluid matrix changes from 10 to 40 the addition of sand particles does not significantly alter the rheological properties of the matrix unless the volumetric concentration of sands exceeds 0 20

cyclic strength of a natural liquefiable sand stabilized with colloidal silica grout this paper summarizes the experimental results of a series of cyclic simple shear tests on liquefiable silty sand with and without sample improvement with colloidal silica grout the objective of t

shear band formation observed in ring shear tests on sandy soils shear band formation is an important factor in understanding failures in soil in this paper shear localization and shear band formation and evolution are examined using ring shear tests performed on three sands prepared by air pluviation a transparent outer confining ring was used to visualize formation and evolution of the entire shear band by comparing the ring shear stress paths with visual observations made during shearing the writers show that the specimen shears uniformly over its entire height prior to shear localization bifurcation under constant volume and drained conditions occurs as the soil fully mobilizes its effective friction angle and subsequent shear displacements occur only within the shear band consistent with previous studies the final thickness of the observed shear band ranged from 10 to 14 times the median particle diameter substantial particle damage occurred within the shear band after large displacements particularly for dilative specimens causing additional strain softening in contractive specimens and a second phase transformation and considerable strain softening in dilative specimens

outburst flood forecasting by monitoring glacier dammed lake using satellite images of karakoram mountains china abstract glacier lake outburst floods glofs that originate in the shaksgam valley on the northern slope of the karakoram mountains china occur frequently and they cause many local and regional disasters in the yarkant river basin in order to monitor and assess their hazard potential this study used both hj 1a b and landsat tm etm oli satellite images to investigate the formation drainage processes of the kyagar glacier dammed lake since 2009 results show that four formation drainage processes of the lake occurred with estimated maximum lake water volumes of 50 7 10 6 49 8 10 6 49 2 10 6 and 34 9 10 6 m 3 in 2009 2015 and in july and august 2016 respectively a statistical relationship based on the observed lake water volume and peak discharge at the hydrometric station during 1959 2008 was found relatively effective for forecasting peak glof discharge with an average relative error of 24 in comparison with observed values at the hydrometric station dynamic changes of the kyagar glacier especially its advances since 2013 were directly responsible for the repeated thickening of the glacial dam and formation of the lake this study provides an effective method for monitoring and forecasting glofs in the yarkant river basin

recent climatic change and catastrophic geomorphic processes in mountain environments climatic warming during the last 100 150 years has resulted in a significant glacier ice loss from mountainous areas of the world certain natural processes which pose hazards to people and development in these areas have accelerated as a result of this recent deglaciation these include glacier avalanches landslides and slope instability caused by glacier debuttressing and outburst floods from moraine and glacier dammed lakes in addition changes in sediment and water supply induced by climatic warming and glacier retreat have altered channel and floodplain patterns of rivers draining high mountain ranges the perturbation of natural processes operating in mountain environments caused by recent climatic warming ranges from tens of decades for moraine dam failures to hundreds of years or more for landslides the recognition that climatic change as modest as that of the last century can perturb natural alpine processes has important implications for hazard assessment and future development in mountains even so these effects are probably at least an order of magnitude smaller than those associated with late pleistocene deglaciation ca 15 000 to 10 000 years ago

hydraulic conductivity of homogenized tailings from hard rock mines tailings produced by milling for one extraction from hard rock mines which range in size from clay to fine sand have relatively low hydraulic conductivity k the value of k must be known with a certain degree of certainty to analyze consolidation and seepage conditions in and around tailings ponds in this paper the authors present the results of a laboratory investigation on hydraulic conductivity of homogenized tailings from hard rock mines after describing some of the basic properties of four different materials including mineralogy grain size atterberg limits compaction characteristics and consolidation curves permeability test results are given the hydraulic conductivity value usually varies between 10 4 and 10 5 cm s the effect of various factors on this value including void ratio and grain size is then discussed in relation to predictive models it is shown that a modified version of the kozeny carman equation in which a tortuosity factor and a grain size distribution function are i

assessment of the liquefaction susceptibility of fine grained soils observations from recent earthquakes and the results of cyclic tests indicate that the chinese criteria are not reliable for determining the liquefaction susceptibility of fine grained soils fine grained soils that liquefied during the 1994 northridge 1999 kocaeli and 1999 chi chi earthquakes often did not meet the clay size criterion of the chinese criteria cyclic testing of a wide range of soils found to liquefy in adapazari during the kocaeli earthquake confirmed that these fine grained soils were susceptible to liquefaction it is not the amount of clay size particles in the soil rather it is the amount and type of clay minerals in the soil that best indicate liquefaction susceptibility thus plasticity index pi is a better indicator of liquefaction susceptibility loose soils with pi 0 85 were susceptible to liquefaction and loose soils with 12 0 8 were systematically more resistant to liquefaction soils with pi 18 tested at low effective confining stresses

erodibility of cohesive streambeds in the loess area of the midwestern usa excess stress parameters critical shear stress c and erodibility coefficient k d for degrading channels in the loess areas of the midwestern usa are presented based on in situ jet testing measurements critical shear stress and k d are used to define the erosion resistance of the streambed the jet testing apparatus applies hydraulic stresses to the bed and the resulting scour due to the impinging jet is related to the excess stress parameters streams tested were primarily silt bedded in texture with low densities which is typical of loess soils results indicate that there is a wide variation in the erosion resistance of streambeds spanning six orders of magnitude for c and four orders of magnitude for k d erosion resistance was observed to vary within a streambed from streambed to streambed and from region to region an example of the diversity of materials within a river system is the yalobusha river basin in mississippi the median value of c for the two primary bed materials naheola and porters creek clay formations was 1 31 and 256 pa respectively streambeds composed of the naheola formation are readily eroded over the entire range of shear stresses whereas only the deepest flows generate boundary stresses great enough to erode streambeds composed of the porters creek clay formation therefore assessing material resistance and location is essential in classifying and modelling streambed erosion processes of these streams

on the formation of tide produced seiches and double high waters in coastal seas we describe a mechanism by which the tide forcing a coastal water body produces an oscillation at the natural period of the water body a seiche around the time of high water the seiche appears as a distortion in the tidal curve which can under certain conditions produce a double high water the formation of the seiche is explored with a numerical simulation of a sea strait forced by the tide at its open ends a seiche of wavelength equal to twice the length of the strait is formed when the mean depth of the strait is similar to the tidal range the rapid reduction of friction as high water is approached appears to be an important part of the formation process observations of water level in the centre of a shallow sea strait in north wales confirm that there is a residual oscillation around high water with the form of a damped seiche the crest of the seiche occurs just before and the trough just after the maximum in the fitted tidal curve the seiche slows the fall of the tide after high water and on one occasion at neap tides the fall is reversed and a double high water is formed it is possible that this mechanism hitherto unidentified contributes to the formation of double high waters in other shallow coastal locations

prediction and assessment of multiple glacial lake outburst floods scenario in pho chu river basin bhutan in this study the characteristic of multiple glacial lake outburst floods glofs in the pho chu river basin in bhutanese himalayas is evaluated to help assess the potential impact thorthormi cho tc and lugge cho lc in the east branch and two unnamed lakes labelled a and b in the west branch of pho chu are chosen for the study numerical models were employed to simulate different involved processes the results show that the peak sediment discharge in the east branch of the pho chu river by the tc dam breach reached about 5000 m3 s during the first glof at 4 km whereas by the lc dam breach is about 600 m3 s second glof at 6 km however the highest peak hydrographs sediment and water mixture calculated during the first and second glof are about 10 000 m3 s at the 18 km section and about 23 000 m3 s at the 10 km section respectively in the west branch of pho chu erosion and depositions are the frequent intermittent local processes during the first glof event from lake a because the first event stabilized the irregular river bed profile there is not much sediment discharge developed during the second glof from lake b at the 17 km section of the west branch the peak hydrograph reached about 9000 m3 s during the first event against the peak of about 800 m3 s during the second event the results suggest that even if multiple dam breaches occur simultaneously glof surges pass through the main river channel at different times with very different flood characteristics the differences in travel time and flood characteristics mostly depend on the distributions of bed slope and potential erosion depth along the reach further the amount of sediment accumulated in and transported by each surge is reliant on the temporal geomorphologic setting of the river and therefore on the impact of the previous glof on riverbed profile and potential erosion depth the robustness in peak glof hydrographs is associated with sediment flow dynamics as a consequence serious inundation of punakha lobeysa and major portion of wangdue phodrang is anticipated copyright 2011 john wiley sons ltd

residual flow bedforms and sediment transport in a tidal channel modelled with variable bed roughness abstract the frictional influence of the seabed on the tidal flow in shelf seas and estuaries is usually modelled via a prescribed spatially temporally invariant drag coefficient in practice the seabed exhibits considerable variability particularly spatially that should in principle be included in simulations local variations in the seabed roughness k s alter the flow strength and hence local sediment transport rates the effect of using a spatially temporally varying k s is assessed here with reference to a tidal channel menai strait n wales in which the variability of the bedforms has been monitored using multi beam surveying the channel not only exhibits strong tidal flow but also a residual induced flow that is used here as diagnostic to assess various bed roughness formulations tested in a telemac model tidal simulations have been carried out with both constant and temporally spatially variable k s and the predicted residual flow is shown to be sensitive to these representations for a mean spring neap sn cycle with variable k s the average residual flow is calculated to be 525 m 3 s 1 consistent with observations this residual flow can be recovered using imposed constant values of k s in the range 0 15 m to 0 3 m the results suggest that the overall effective roughness of the seabed is less than half of the maximum local roughness due to the dunes in mid channel but more than the spatially averaged k s value in the channel as a whole by about 50 simulations carried out with an m 2 alone tide using variable k s produce a somewhat smaller by 7 residual flow of 491 m 3 s 1 the use of an equivalent m 2 tide of amplitude enhanced by 7 3 reconciles these estimates the main contribution to k s is made by dunes which are modelled using van rijn s 2007 formulation subject to an additional history effect the modelled k s is found to equal approximately the observed height of the dunes along mid channel transects rather than half the height as expected this is attributed to the non equilibrium nature of the bedforms in the reversing tidal flow which exhibited shorter wavelength and more symmetrical profiles than dunes in steady flow

quick release of internal water storage in a glacier leads to underestimation of the hazard potential of glacial lake outburst floods from lake merzbacher in central tian shan mountains glacial meltwater and ice calving contribute to the flood volume of glacial lakes such as lake merzbacher in the tian shan mountains of central asia in this study we simulated the lake s volume by constructing an empirical relationship between the area of lake merzbacher determined from satellite images and the lake s water storage derived from digital elevation models results showed that the lake water supply rate before glacial lake outburst floods glofs generally agreed well with those during the glofs from 2009 to 2012 but not in 2008 and 2015 furthermore we found that the combination of glacial meltwater and ice calving is not enough to fully explain the supply rate during glofs in 1996 and 1999 suggesting other factors affect the supply rate during glofs as well to examine this further we compared the water supply rate before and during glof events in 1999 and 2008 we inferred that quickly released short term and intermediate term water storage by glaciers have likely contributed to both flood events in those years this study highlights the need to improve our understanding of the supply component of outburst floods such as irregularly released stored water may lead to glof events with generally three different types case i singular event triggered englacial water release case ii glacier melt due to temperature changes and case iii englacial water release mixed with glacier melt

seismic table investigation of the effect of inclusions on the cyclic behaviour of tailings when subjected to cyclic loadings such as those induced by earthquakes hard rock mine tailings may undergo liquefaction such a response can be damaging to the tailings impoundment and in the ca

colloquium 2004 hydrogeotechnical properties of hard rock tailings from metal mines and emerging geoenvironmental disposal approaches tailings are ground rock particles from which the valuable minerals or metals have been extracted an historical overview on hard rock mines shows that since the 1930s it has become current practice to pump the tailings into storage areas circumscribed by dykes made of the tailings themselves however numerous physical and chemical stability problems were observed mainly owing to the particular hydrogeotechnical and mineralogical properties of the tailings therefore modifications to the conventional methods were proposed but these were relatively costly not always efficient and sometimes difficult to implement new management methods that improve the physical and or chemical stability have hence been developed to reduce environmental risks associated with tailings storage namely densified tailings environmental desulphurization covers built with tailings and co disposal of tailings and waste rock even if many aspects need to be optimized these approaches can be considered today as interest

infragravity currents in a small ria estuary amplified coastal edge waves abstract observations are presented of estuarine infragravity oscillations in a very small estuary the ria de santiuste northern spain that discharges into a bay time scale calculations and measurements indicate that the most likely source of amplified infragravity waves within the estuary are coastal edge waves which appear to be resonating between the headlands of the bay and onshore offshore seiching of waters that may be resonating between the beach and the bay s seaward limit infragravity waves in the estuary have a narrow power dominant periodicity range of 4 3 4 8 min generally only very weak waves and at other periodicities occur within the tidal river when it is unaffected by the tide although infragravity water level amplitudes are small in the tidal river typically 0 01 m during high water the corresponding velocity amplitudes are significant typically 0 1 m s 1 despite the occurrence of high runoff conditions during these measurements within the estuary and close to the mouth near bed salinity shows considerable variability that is a consequence of salt wedge oscillations with periodicities that are within the range of 4 3 4 8 min model results for simulated neap to spring high water water levels show that wave periodicities in the range 3 5 4 5 min correspond approximately to 3 4 resonances the model also indicates that an effect of low runoff is to greatly enhance resonant behaviour within the estuary such that water level amplitudes of 0 02 m at the mouth can produce wave currents as fast as 0 4 m s 1 within the estuary compared with 0 1 m s 1 during high runoff

gps measurements of present day convergence across the nepal himalaya the high elevations of the himalaya and tibet result from the continuing collision between india and asia which started more than 60 million years ago1 4 from geological and seismic studies of the slip rate of faults in asia5 it is believed that approximately one third of the present day convergence rate between india and asia 58 4mmyr 1 is responsible for the shortening uplift and moderate seismicity of the himalaya great earthquakes also occur infrequently in this region releasing in minutes the elastic strain accumulated near the boundary zone over several centuries and accounting for most of the advance of the himalaya over the plains of india the recurrence time for these great earthquakes is determined by the rate of slip of india beneath tibet which has hitherto been estimated indirectly from global plate motions6 from the slip rates of faults in asia7 8 from seismic productivity9 and from the advance of sediments on the northern ganges plain10 here we report geodetic measurements using the global positioning system gps of the rate of contraction across the himalaya which we find to be 17 52 2 mm yr 1 from the form of the deformation field we estimate the rate of slip of india beneath tibet to be 20 5 2 mmyr 1 strain sufficient to drive one or more great himalayan earthquakes with slip similar to that accompanying the magnitude 8 1 bihar nepal 1934 earthquake may currently be available in western nepal

hydrodynamic characteristics of the tam pokhari glacial lake outburst flood in the mt everest region nepal the tam pokhari glacial lake outburst flood glof which occurred in 1998 in the mt everest region of nepal was evaluated using hydrodynamic models to gain a better understanding of the flow behaviour the flood wave was analysed separately under rigid and erodible boundary conditions in both cases the calculated dam breach hydrograph which had a peak discharge of about 10 000 m3 s was routed through the inkhu river which originates from the lake the morphologic changes along the river were also analysed and the results were compared with satellite images field observations and recorded data in the case of rigid boundaries the routing procedure gradually attenuated the peaks of the hydrographs to account for hydraulic pooling in narrow gorges and storage in the channel in the case of erodible boundaries such effects were minimized due to the increment in channel capacity associated with erosion by debris flow the study revealed that the glof event produced a large scale debris flow additionally the results revealed that erosion and deposition took place intermittently but that approximately 440 000 m3 of sediment was deposited about 14 km downstream from the lake mouth the calculated peak of the water and sediment mixture at 14 4 km was found to be 30 000 m3 s which is almost 6 times as large as that observed when the rigid boundary conditions were used further the increase in the peaks of the hydrographs due to sediment transport was the primary reason for the destruction associated with the glof these findings suggest that the local sedimentology and topography as well as other geo hazard conditions in the area should be carefully evaluated before recommending any control measures against glofs in the himalayan region copyright 2009 john wiley sons ltd

fourth avenue landslide during 1964 alaskan earthquake this paper presents a reevaluation of the fourth avenue landslide in anchorage that occurred during the 1964 alaskan earthquake laboratory constant volume ring shear and field vane shear tests were used to measure the undrained peak and residual shear strength of the bootlegger cove clay the results of these tests are presented and compared to back calculated shear strengths of the bootlegger cove clay the comparison shows that slide blocks that moved less than 0 15 m mobilized at least 80 of the undrained peak shear strength slide blocks that moved between 0 15 to 2 5 m mobilized an undrained shear strength between the peak and residual shear strengths slide blocks that displaced more than 2 5 m mobilized the undrained residual strength

assessing the influence of the merzbacher lake outburst floods on discharge using the hydrological model swim in the aksu headwaters kyrgyzstan nw china glacial lake outburst floods glof often have a significant impact on downstream users including their effects in hydrological models identifying past occurrences and assessing their potential impacts are challenges for hydrologists working in mountainous catchments the regularly outbursting merzbacher lake is located in the headwaters of the aksu river the most important source of water discharge to the tarim river northwest china modelling its water resources and the evaluation of potential climate change impacts on river discharge are indispensable for projecting future water availability for the intensively cultivated river oases downstream of the merzbacher lake and along the tarim river the semi distributed hydrological model swim was calibrated to the outlet station xiehela on the kumarik river by discharge the largest tributary to the aksu river the glacial lake outburst floods add to the difficulties of modelling this high mountain heavily glaciated catchment with poor data coverage and quality the aims of the study are to investigate the glacier lake outburst floods using a modelling tool results include a two step model calibration of the kumarik catchment an approach for the identification of the outburst floods using the measured gauge data and the modelling results and estimations of the outburst flood volumes results show that a catchment model can inform glof investigations by providing normal i e without the outburst floods catchment discharge the comparison of the simulated and observed discharge proves the occurrence of glofs and highlights the influences of the glofs on the downstream water balance 2013 the authors hydrological processes published by john wiley sons ltd

liquefaction and drainage in stratified soil remediation schemes for the treatment of liquefiable ground such as vertical drains have evolved over the last 30 years largely as a result of consideration of uniform sand beds however many liquefiable sites also contain thin layers of silts and clays which will act as an obstacle to fluid dissipating from liquefying sands such that the performance and requirements of a remediation scheme will be different in particular water films may be produced this paper presents results from a series of dynamic centrifuge experiments on vertical drains in level liquefiable sand deposits centrifuge tests were conducted both with and without surface fine layers the drains prevented sand boiling and the thin surface fine layers did not significantly affect excess pore pressure response a further centrifuge test on a thin layer of low permeability fines separating two liquefiable sandy layers showed evidence suggesting that material boiled from the lower sand to the upper sand in the absence of a drain through the fines all of the experiments suggest that the presence of unblocked vertical drains prevent water film formation

effect of waste rock inclusions on the seismic stability of an upstream raised tailings impoundment a numerical investigation over the years seismic activity has been a relatively common cause of tailings impoundment failure the flow of liquefied tailings from such ruptures can result in very severe consequences includ

estimating slope of critical state line from cone penetration test an update estimation of density from cone penetration test cpt results is challenging as cone resistance is a function of a number of soil properties particularly compressibility while many of the relev

integrated monitoring of mountain glaciers as key indicators of global climate change the european alps the internationally recommended multi level strategy for monitoring mountain glaciers is illustrated using the example of the european alps where especially dense information has been available through historical times this strategy combines in situ measurements mass balance length change with remote sensing inventories and numerical modelling it helps to bridge the gap between detailed local process oriented studies and global coverage since the 1980s mass balances have become increasingly negative with values close to 1 m w e a 1 during the first 5 years of the 21st century the hot dry summer of 2003 alone caused a record mean loss of 2 45 m w e roughly 50 above the previous record loss in 1998 more than three times the average between 1980 and 2000 and an order of magnitude more than characteristic long term averages since the end of the little ice age and other extended periods of glacier shrinkage during the past 2000 years it can be estimated that glaciers in the european alps lost about half their total volume roughly 0 5 a 1 between 1850 and around 1975 another 25 or 1 a 1 of the remaining amount between 1975 and 2000 and an additional 10 15 or 2 3 a 1 in the first 5 years of this century

a laboratory investigation of the dynamic properties of tailings the dynamic response of tailings from a gold mine located in western quebec was evaluated using cyclic laboratory testing these tailings are classified as nonplastic silt and sand specimens of the tailings were prepared as slurries consolidated to vertical effective stresses of 100 400 kpa and subjected to cyclic direct simple shear testing with cyclic stress ratio csr values between 0 075 and 0 15 the shear modulus reduction of the tailings under cyclic loading was found to be fairly similar to that described for clean sands in the literature the cyclic resistance ratio crr which reflects the liquefaction resistance of the samples was not significantly affected by the effective consolidation stress in the range considered here analysis of test results with the simplified method of liquefaction evaluation indicates that this method may be applicable to these tailings however other factors such as the possible effects of layering and ageing of the tailings in situ should also be consider

liquefaction susceptibility criteria for silts and clays new liquefaction susceptibility criteria for saturated silts and clays are presented that are based on the mechanics of their stress strain behavior and which provide improved guidance for selecting engineering procedures for estimating potential strains and strength loss during seismic loading monotonic and cyclic undrained loading test data for silts and clays show that they transition over a fairly narrow range of plasticity indices pi from soils that behave more fundamentally like sands sand like behavior to soils that behave more fundamentally like clays clay like behavior with the distinction having a direct correspondence to the type of engineering procedures that are best suited to evaluating their seismic behavior it is recommended that the term liquefaction be reserved for describing the development of significant strains or strength loss in fine grained soils exhibiting sand like behavior whereas the term cyclic softening failure be used to describe similar phenomena in fine grained soils exhibiting clay like behavior for practical purposes clay like behavior can be expected for fine grained soils that have pi 7 although a slightly lower transition point for soils with a cl ml classification perhaps pi 5 or 6 would be equally consistent with the available data issues related to the practical application of these criteria are discussed

volumetric strains of clean sands subject to cyclic loads we utilize simple shear testing to investigate the volume change of clean sands subject to cyclic loads we examine the effects of a number of compositional and environmental factors on the vertical strain at 15 uniform shear strain cycles and on the cycle to cycle variation of vertical strain the compositional factor found to principally affect seismic compression susceptibility is relative density compositional factors found to not significantly affect cyclic volume change include gradation parameters mean grain size and uniformity coefficient particle angularity soil fabric mineralogy and void ratio breadth e emin an environmental factor found to affect seismic compression susceptibility is confining stress with volumetric strains decreasing with increasing stress environmental factors that do not significantly affect seismic compression susceptibility for clean sands are saturation and age stress history can decrease vertical strains from seismic compression for certain conditions but