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

topography relief and trmm derived rainfall variations along the himalaya 1 along the southern himalayan topographic front the indian summer monsoon modulates erosive processes and rates to investigate the influence of topography and relief on rainfall generation and resultant erosion we processed satellite rainfall amounts for the last 8 years 1998 2005 from the tropical rainfall measurement mission trmm based upon a spatial resolution of 5 5 km for the himalaya we identify 1 the spatial distribution of rainfall and 2 the large scale relationships between topography relief and rainfall locations our results show two distinct rainfall maxima along strike in the himalaya the first outer rainfall peak occurs along the southern margin of the lesser himalaya within a narrow band of mean elevation 0 9 0 4 km and mean relief 1 2 0 2 km the second discontinuous inner band typically occurs along the southern flank of the greater himalaya elevation and relief both 2 1 0 3 km

coupling glacial lake impact dam breach and flood processes a modeling perspective glacial lake outburst floods glofs are highly mobile mixtures of water and sediment that occur suddenly and are capable of traveling tens to hundreds of kilometers with peak discharges and volumes several orders of magnitude larger than those of normal floods they travel along existing river channels in some instances into populated downstream regions and thus pose a risk to people and infrastructure many recent events involve process chains such as mass movements impacting glacial lakes and triggering dam breaches with subsequent outburst floods a concern is that effects of climate change and associated increased instability of high mountain slopes may exacerbate such process chains and associated extreme flows modeling tools can be used to assess the hazard of potential future glofs and process modeling can provide insights into complex processes that are difficult to observe in nature a number of numerical models have been developed and applied to simulate different types of extreme flows but such modeling faces challenges stemming from a lack of process understanding and difficulties in measuring extreme flows for calibration purposes here we review the state of knowledge of key aspects of modeling glofs with a focus on process cascades analysis and simulation of the onset propagation and potential impact of glofs are based on illustrative case studies numerical models are presently available for simulating impact waves in lakes dam failures and flow propagation but have been used only to a limited extent for integrated simulations of process cascades we present a spectrum of case studies from patagonia the european alps central asia and the himalayas in which we simulate single processes and process chains of past and potential future events we conclude that process understanding and process chain modeling need to be strengthened and that research efforts should focus on a more integrative treatment of processes in numerical models

vanadiferous minerals from the nereus deep red sea the chemical analysis by emp eds of 140 samples in cores from six red sea troughs and basins has led to the discovery in the nereus deep of high vanadium concentrations up to 1 3 v2o3 in several bulk samples and to the isolation of a major magnetite phase this vanado magnetite remarkable for its high content of vanadium mean 1 45 v2o3 and its lack of titanium is frequently zoned the v content decreasing toward the outer zones oxides with up to 42 v2o3 have also been found since the origin of the magnetite is clearly authigenic its high vanadium and low titanium concentrations are traced back to the differential hydrothermal leaching of fe ti oxides which occur profusely in basic eruptive rock clasts actually present in some of the overlying seams authors

removal of wavelet dispersion from ground penetrating radar data wavelet dispersion caused by frequency dependent attenuation is a common occurrence in ground penetrating radar gpr data and is displayed in the radar image as a characteristic blurriness that increases with depth correcting for wavelet dispersion is an important step that should be performed before gpr data are used for either qualitative interpretation or the quantitative determination of subsurface electrical properties over the bandwidth of a gpr wavelet the attenuation of electromagnetic waves in many geological materials is approximately linear with frequency as a result the change in shape of a radar pulse as it propagates through these materials can be well described using one parameter q related to the slope of the linear region assuming that all subsurface materials can be characterized by some q value the problem of estimating and correcting for wavelet dispersion becomes one of determining q in the subsurface and deconvolving its effects using an inverse q filter we present a

experimental investigation on the longitudinal evolution of landslide dam breaching and outburst floods abstract accurate prediction of the evolution of a landslide dam that is breached due to overtopping failure is necessary to estimate the outflow hydrograph and the resulting inundation in this study physical flume tests on the breaching of landslide dams were conducted a wide grain size distribution with unconsolidated dam material was used dam breaching was initiated by cutting a notch across the crest of the dam adjacent to the side wall of the flume this allowed water to escape from the dam while a steady inflow of water was continuously supplied upstream the effects of upstream inflow on the timescales and magnitudes of the peak discharges and the time to inflection point were also investigated experimental results reveal that the whole hydrodynamic process of dam breaching can be divided into three stages defined by clear inflection points and peak discharge a new longitudinal evolution model is proposed this model captures the initial increase of the soil erosion rate of landslide dam and its subsequent decrease along the longitudinal direction in addition a linear relationship between the soil erosion rate and shear stress of water flow was observed and this is similar to that observed in large scale natural landslide dams furthermore soil erosion resistances of landslide dam against water flow above are observed to increase with the concentration of entrained sediments along the flow direction

mineralogy and geochemistry of epigenetic features in metalliferous sediment atlantis ii deep red sea finely laminated and undisturbed except in the area of the southwest basin in this part bedding resedimentation and brecciation are common in addition some sediment cores contain vein minerals precipitated in open fissures which crosscut unlithified metalliferous sediments these veins are the conduits by which new hot brine vents into the deep vein mineralogy is dominated by anhydrite talc smectite pyrite sphalerite and chalcopyrite vertical zonation due to cooling and reaction of the incoming brine as it rises through the metalliferous sediment near the southwest basin west basin transition metalliferous sediment has been locally recrystallized to a hematite magnetite pyroxene assemblage probably due to the intrusion of basalt into the metalliferous sediments modified journal abstract

geochemistry of magnetite from the giant paleoproterozoic dahongshan fe cu deposit sw china constraints on nature of ore forming fluids and depositional setting abstract the dahongshan fe cu ore deposit hosted in the paleoproterozoic meta volcanic and meta sedimentary sequences is a giant deposit in the fe cu metallogenic province of southwestern china two ore types have been identified 1 massive and disseminated fe ores hosted dominantly in meta volcanic rocks and 2 disseminated and banded fe cu ores in meta sedimentary rocks magnetite presents in all orebodies and is dominant in the fe ores chemistry of magnetite suggest that the fluids for iron mineralization in the fe and fe cu orebodies are likely chemically similar and cogenetic minor sulfides e g molybdenite occur at the end of iron mineralization stage indicating the gradually decrease in oxygen fugacity for the mineralizing fluids with magnetite precipitation along with evolution mineralizing fluids generate magnetite with depletions in cr ni ga and v but enrichments in mn sn and co which are primarily reflective of the temperature decrease of fluids we have discovered some magnetite grains that are extremely rich in v 10000 ppm but low in ti and cr geochemical patterns suggest that they were formed by fluids similar to those of ordinary ores available knowledge about the unique high v magnetite indicates highly reduced marine environments for its generation ore bulk ree patterns showing remarkable positive eu anomalies and absence of obvious ce anomalies suggest a bif like marine environment consistent with the morphology of both fe and fe cu orebodies our results provide independent evidence for submarine environment in the formation of the giant precambrian stratiform fe cu ore deposit

the 2015 chileno valley glacial lake outburst flood patagonia abstract glacial lake outburst floods glofs have become increasingly common over the past century in response to climate change posing risks for human activities in many mountain regions in this paper we document and reconstruct the sequence of events and impact of a large glof that took place in december 2015 in the chileno valley patagonia hydrograph data suggests that the flood continued for around eight days with an estimated total discharge of 105 6 106 m3 of water the sequence of events was as follows 1 a large debris flow entered the lake from two steep and largely non vegetated mountain gullies located northeast of the chileno glacier terminus 2 water displaced in the lake by the debris flow increased the discharge through the chileno lake outflow 3 lake and moraine sediments were eroded by the flood 4 eroded sediments were redistributed downstream by the glof the post glof channel at the lake outlet widened in some places by 130 m and the surface elevation of the terrain lowered by a maximum of 38 8 1 5 m farther downstream large amounts of entrained sediment were deposited at the head of an alluvial plain and these sediments produced an 340 m wide fan with an average increase in surface elevation over the pre glof surface of 4 6 1 5 m we estimate that around 3 5 million m3 of material was eroded from the flood affected area whilst over 0 5 million m3 of material was deposited in the downstream glof fan the large debris flow that triggered the glof was probably a paraglacial response to glacier recession from its little ice age limits we suggest that glofs will continue to occur in these settings in the future as glaciers further recede in response to global warming and produce potentially unstable lakes detailed studies of glof events are currently limited in patagonia and the information presented here will therefore help to inform future glacial hazard assessments in this region

a consensus estimate for the ice thickness distribution of all glaciers on earth knowledge of the ice thickness distribution of the world s glaciers is a fundamental prerequisite for a range of studies projections of future glacier change estimates of the available freshwater resources or assessments of potential sea level rise all need glacier ice thickness to be accurately constrained previous estimates of global glacier volumes are mostly based on scaling relations between glacier area and volume and only one study provides global scale information on the ice thickness distribution of individual glaciers here we use an ensemble of up to five models to provide a consensus estimate for the ice thickness distribution of all the about 215 000 glaciers outside the greenland and antarctic ice sheets the models use principles of ice flow dynamics to invert for ice thickness from surface characteristics we find a total volume of 158 41 103 km3 which is equivalent to 0 32 0 08 m of sea level change when the fraction of ice located below present day sea level roughly 15 is subtracted our results indicate that high mountain asia hosts about 27 less glacier ice than previously suggested and imply that the timing by which the region is expected to lose half of its present day glacier area has to be moved forward by about one decade the ice volume of glaciers outside the greenland and antarctic ice sheets totals about 158 000 km3 with about 27 less ice in high mountain asia than thought according to multiple models that estimate ice thickness from surface characteristics

mineralogical and geochemical constraints on the origin of ferromanganese crusts from the rivera plate western margin of mexico abstract marine hydrogenetically precipitated ferromanganese crusts are widespread in the pacific ocean they occur as pavements coating volcanic or sedimentary hard rock substrates mainly on the slopes of seamounts plateaus and hills in ocean basins and continental margins we studied three ferromanganese crusts from one dredge haul from the rivera plate western margin of mexico which are up to 15 mm thick and grow directly on a substrate of pillow basalt fragments they consist of laminated botryoidal porous aggregates mostly of fe and mn oxyhydroxides and up to 10 silicates xrd analysis showed the predominance of poorly crystallized mineral phases in the crusts that include mn feroxyhyte and vernadite and an authigenic smectite like clay detrital minerals probably derive from granodiorites of the eastern wall of the neighboring middle america trench scattered barite grains occur on the crust surface and suggest plume fall out derived from hydrothermal vents although a possible pelagic source cannot be dismissed ratios between major fe mn si and trace co ni cu elements reveal that such crusts are predominantly hydrogenetic in origin although they show a hydrothermal influence that increases in the outer layers iron contents range from 16 2 to 25 2 wt and manganese from 3 4 to 14 5 wt the fe mn ratio ranges from 1 6 to 7 0 the sio 2 al 2 o 3 ratio ranges from 4 3 to 6 6 indicating the presence of biogenic silica radiolarians the concentrations of copper up to 383 ppm and cobalt up to 534 ppm are significantly below those of the typical hydrogenetic crusts whereas ni up to 1320 ppm is about the same or slightly lower ree normalized profiles and ree values 486 to 732 ppm match those reported for hydrogenetic crusts but suggest a hydrothermal contribution for the later crust layers the inferred crust growth rates using the co chronometer 44 and 229 mm myr are higher than those reported for pure hydrogenetic crusts mostly 1 to 6 mm myr thus indicating an increasing hydrothermal influence the highest growth rate 229 mm myr corresponding to the outer crust layers suggests a regional hydrothermal input of iron and manganese to seawater the intensification of regional submarine hydrothermal activity began about 13 000 yr ago and may be related to the tectonic activity in the complex junction of the rivera cocos pacific and north america plates

the maximum discharge of outburst floods caused by the breaching of man made and natural dams the sudden release of water impounded in natural and man made reservoirs has been responsible for some major disasters in mountainous regions of the world recent natural damming events and failures of natural dams have illustrated the need to examine the nature and magnitude of outburst floods and the behaviour of debris dams in general an empirical relationship between maximum discharge qmax and volume of water released during the outburst event vmax is established qmax 0 72vmax0 53 for man made dams and the relationship is thought applicable to the breaching of natural debris dams landslides and moraines this relationship allows a first order estimate to be made of qmax in the vicinity of the breach for a given vmax during the failure of a man made dam or a natural debris dam key words outburst floods man made dams natural dams landslide dam failure

chemical and isotopic 87sr 86sr δ18o δd constraints to the formation processes of red sea brines abstract about twenty deeps filled with hot brines and or metalliferous sediments are located along the red sea axis these brines present a well suited framework to study the hydrothermal activity in such a young ocean the present study outlines the results of a geochemical approach combining major trace element and isotopic oxygen hydrogen strontium analyses of brines in six of the deeps to evaluate different processes of brine formation and to compare the evolution of each deep important heterogeneities in temperature salinity hydrographic structure and chemistry are recorded each brine having its own characteristics the intensity of hydrothermal circulation varies among the deeps and ranges from being strong atlantis ii and nereus to weak port soudan and even to negligible valdivia and suakin and it varies along the entire red sea axis these observations do not favour a unique formational model for all of the brines for example the brines of the suakin deep appear to have been formed by an old sea water which dissolved evaporite beds without significant fluid circulation and hydrothermal input while others such as atlantis ii or nereus deeps appear to be dominated by hydrothermal influences a striking feature is the absence of a relationship between the position of the deeps along the axis and their evolutionary maturity

finding the strike direction of fractures using gpr gpr reflection energy varies with antenna orientation relative to the strike and dip of the reflector this directional dependence of gpr responses was investigated through numerical experiments and was used to estimate the azimuth of fractures and joints three antenna configurations were considered in this study perpendicular broadside yy mode parallel broadside xx mode and cross polarization yx mode the reflection energy in the cross polarization mode shows a shape characteristic similar to the strike regardless of the dip angle those in the other two modes show quite different amplitudes from the strike depending on the dip angle we have developed a strike direction finding scheme using data obtained from the three different modes for the same survey line the azimuth angle of each reflector was displayed in colour on the gpr profile this scheme was applied to a field survey at a granite quarry in southern korea the gpr profiles showed different images of the reflectors depending on the antenna configuration the estimated azimuths of reflectors obtained using our scheme matched fairly well with those of known fractures and joints

how well can we simulate complex hydro geomorphic process chains the 2012 multi lake outburst flood in the santa cruz valley cordillera blanca peru changing high mountain environments are characterized by destabilizing ice rock or debris slopes connected to evolving glacial lakes such configurations may lead to potentially devastating sequences of mass movements process chains or cascades computer simulations are supposed to assist in anticipating the possible consequences of such phenomena in order to reduce the losses the present study explores the potential of the novel computational tool r avaflow for simulating complex process chains r avaflow employs an enhanced version of the pudasaini 2012 general two phase mass flow model allowing consideration of the interactions between solid and fluid components of the flow we back calculate an event that occurred in 2012 when a landslide from a moraine slope triggered a multi lake outburst flood in the artizon and santa cruz valleys cordillera blanca peru involving four lakes and a substantial amount of entrained debris along the path the documented and reconstructed flow patterns are reproduced in a largely satisfactory way in the sense of empirical adequacy however small variations in the uncertain parameters can fundamentally influence the behaviour of the process chain through threshold effects and positive feedbacks forward simulations of possible future cascading events will rely on more comprehensive case and parameter studies but particularly on the development of appropriate strategies for decision making based on uncertain simulation results 2017 the authors earth surface processes and landforms published by john wiley sons ltd

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

rising river flows throughout the twenty first century in two himalayan glacierized watersheds greater himalayan glaciers are retreating and losing mass a combination of the latest ensemble of climate models combined with a glacio hydrological model suggests that in two contrasting watersheds in the greater himalaya glaciers will recede but net glacier melt runoff is on a rising limb until at least 2050

a regional scale assessment of himalayan glacial lake changes using satellite observations from 1990 to 2015 abstract the himalaya the world s highest mountain ranges are home to a large group of glaciers and glacial lakes glacial lake outburst floods glofs in this region have resulted in catastrophic damages and fatalities in the past decades the recent warming has caused dramatic glacial lake changes and increased potential glof risk in the himalaya however our knowledge on the current state and change of glacial lakes in the entire himalaya is limited this study maps the current 2015 distribution of glacial lakes across the entire himalaya and monitors the spatially explicit evolution of glacial lakes over five time periods from 1990 to 2015 using a total of 348 landsat images at 30 m resolution the results show that 4950 glacial lakes in 2015 cover a total area of 455 3 72 7 km2 mainly located between 4000 m and 5700 m above sea level himalayan glacial lakes expanded by approximately 14 1 from 1990 to 2015 the changing patterns of supraglacial lakes and proglacial lakes are rather complex involving both lake disappearance and emergence many emergent glacial lakes are found at higher elevations especially the new proglacial lakes which have formed as a result of glacier retreat spatially heterogeneous changes of himalayan glacial lakes are observed with the most significant expansion occurring in the southern slopes of the central himalaya increasing glacier meltwater induced by the himalayan atmospheric warming is a primary cause for the observed lake expansion this study provides primary data for future glof risk assessments a total of 118 rapidly expanded glacial lakes are identified as potential vulnerable lakes for the priority of risk assessment

representative lake water extent mapping at continental scales using multi temporal landsat 8 imagery abstract inland lakes important water resources play a crucial role in the global water cycle and are sensitive to climate change and human activities there clearly is a pressing need to understand temporal and spatial variations of lakes at global and continental scales the recent operation of landsat 8 extends the unprecedented landsat record to over 40 years allowing long term large scale lake dynamics mapping at high resolutions using our circa 2000 lake product derived from landsat 7 images as a reference this research produces a circa 2015 map of representative lake extents and distributions and addresses seasonal and inter annual lake area variability using landsat 8 images acquired in lake stable seasons at a continental scale oceania is chosen here as a case study as it contains a large group of salt lakes that exhibit high area variability and has the most intensive image coverage during the first 2 5 year operation of landsat 8 accordingly this paper describes an adaptive algorithm to automate lake mapping for various surface conditions using images acquired during lake stable seasons and a compositing scheme in the vector domain to generate a representative continental mosaic of lake extents from multi temporal mapping our results demonstrate that these strategies and methods produce a highly reliable and representative composite of highly variable lake extents across oceania and are potentially applicable to other large scale lake mapping projects using multi temporal data

reconstructing the chongbaxia tsho glacial lake outburst flood in the eastern himalaya evolution process and impacts abstract glacial lake outburst floods glof are one of the most destructive natural disasters understanding glof evolution and their impacts plays a fundamental role in glof hazard assessment and risk management reconstructing historical glofs is an important exercise because detailed case studies of such glacial hazards are rare which hinders the capacity of glacial hazard practitioners to learn from these events in this study we reconstruct a historical glof from moraine dammed chongbaxia tsho 89 745 e 28 211 n in the eastern himalaya which is a unique case study because the outburst flood cascaded into two further lakes downstream we employ a combination of i multi source and multi temporal satellite imagery ii field investigation including an unmanned aerial vehicle survey iii numerical dam breach and hydrodynamic modelling and iv qualitative and quantitative cryospheric and meteorological analysis to investigate the evolution of the glof hazard simulate moraine dam failure and glof propagation and explore the role that long and short term climate trends played in providing the conditioning factors for the outburst chongbaxia tsho expanded rapidly between 1987 until 2001 in response to glacier recession most likely caused by a regional warming trend of 0 37 c per decade based on satellite image analysis we refine the outburst date to be 6 august 2001 instead of 6 august 2000 as previously reported and attribute an ice avalanche into the glacial lake originating from the receding parent glacier as the most likely trigger for moraine dam failure through dem differencing and lake level decrease we estimate that a total water volume of 27 1 1 6 106 m3 was released from the lake during the event and using dam breach modelling we estimate that the peak discharge at the breach was 6600 m3 s 1 the glof flowed through downstream chongbamang tsho and chongbayong tsho both of which served to attenuate the glof and reduce downstream losses the latter stored an estimated 96 of the flood volume precipitation totals in the weeks preceding the glof exceeded the historical mean by up to 40 and may have contributed to instability of the parent glacier and generation of an ice avalanche with enough impact energy to cause lake water to overtop the moraine dam and initiate breach development a future glof from chongbaxia tsho cannot be ruled out but more field data including detailed lake bathymetry and information pertaining to the sedimentological and geotechnical characteristics of the moraine dam are required for a more robust parameterization of a predictive glof model and quantification of the hazard posed by a future glof

evaluation of tandem x dems on selected brazilian sites comparison with srtm aster gdem and alos aw3d30 abstract a first assessment of the tandem x dems over brazilian territory is presented through a comparison with srtm aster gdem and alos aw3d30 dems in seven study areas with distinct geomorphological contexts vegetation coverage and land use visual analysis and elevation histograms point to a finer effective spatial i e horizontal resolution of tandem x compared to srtm and aster gdem in areas of open vegetation tandem x lower elevations indicate a deeper penetration of the radar signal dems of differences dods allowed the identification of issues inherent to the production methods of the analyzed dems such as mast oscillations in srtm data and mismatch between adjacent scenes in aster gdem and alos aw3d30 a systematic difference in elevations between tandem x 12 m tandem x 30 m and srtm was observed in the steep slopes of the coastal ranges related to the moving window process used to resample the 12 m data to a 30 m pixel size it is strongly recommended to produce a dod with srtm before using aster gdem or alos aw3d30 in any analysis to evaluate if the area of interest is affected by these problems the dods also highlighted changes in land use in the time span between the acquisition of srtm 2000 and tandem x 2013 data whether by natural causes or by human interference in the environment the results show a high level of detail and consistency for tandem x data indicate that the effective horizontal resolution of srtm is coarser than the nominal 30 m and highlight the errors in aster gdem and alos aw3d30 due to mismatch between adjacent scenes in the photogrammetric process

changes in glacial lakes and glaciers of post 1986 in the poiqu river basin nyalam xizang tibet glacial lakes and glaciers are sensitive indicators of recent climate change in the poiqu river basin of southern tibet 60 100 km nw of mt everest landsat imagery defines post 1986 changes in the size and distribution of both glacial lakes and glaciers total area of glaciers in the 229 km2 drainage area has decreased by 20 the number of glacial lakes with areas in excess of 0 020 km2 has increased by 11 and the total area of glacial lakes has increased by 47 the areas of typical large glacial lakes of the area galongco gangxico and cirenmaco have increased by 104 118 and 156 respectively and these increases are confirmed by field investigations comparing the 1986 data the area of glaciers in the basin headwaters has decreased by 46 18 km2 to a present total area of 183 12 km2 an annual rate of change of 3 30 km2 year trends indicate that the total area of glaciers will continue to decrease and that both the numbers and areas of glacial lakes will continue to increase accompanying these trends will be an increased risk of debris flows formed by entrainment of sediment in glacial outburst floods and in surges from both failure and avalanche and landslide induced overtopping of moraine dams based on both the local and world wide history of catastrophes from flows of these origins disaster mitigation must be planned and appropriate engineering countermeasures put in place as soon as possible

ultrawide bandwidth fully polarimetric ground penetrating radar classification of subsurface unexploded ordnance an ultrawide bandwidth uwb ground penetrating radar gpr was used to collect fully polarimetric backscattered data from 10 to 800 mhz using a dual polarization version of the previously developed dielectric loaded horn fed bow tie hfb antenna special processing algorithms were developed to extract the polarization orientation depth and length features of the target under investigation the polarization and resonance features were utilized to discriminate subsurface ordnance from false alarm objects that do not have elongated bodies the classification of a specific type of unexploded ordnance uxo was also performed using the known length information the processed results obtained from an initial blind field test show a very encouraging discrimination performance

apparent apertures from ground penetrating radar data and their relation to heterogeneous aperture fields considering fractures with heterogeneous aperture distributions we explore the reliability of constant aperture estimates derived from ground penetrating radar gpr reflection data we generate geostatistical fracture aperture realizations that are characterized by the same mean aperture and variance but different hurst exponents and cut off lengths for each of the 16 classes of heterogeneity considered we generate 1000 fracture realizations from which we compute gpr reflection data using our recent effective dipole forward model we then use each noise contaminated data set individually to invert for a single apparent aperture that is we assume that the fracture aperture is homogeneous we find that the inferred apparent apertures are only reliable when fracture heterogeneity is non fractal the hurst exponent is close to 1 and the scale of the dominant aperture heterogeneities is larger than the first fresnel zone these results are a direct consequence of the nonlinear character of the thin bed reflection coefficients as fracture heterogeneity is ubiquitous and often fractal our results suggest that robust field based inference of fracture aperture can only be achieved by accounting for the nonlinear response of fracture heterogeneity on gpr data

application of alford rotation to ground penetrating radar data we investigate the application of alford rotation to ground penetrating radar gpr data by recording the reflected field amplitudes using four different configurations we extract information about the orientation of buried objects that have angle dependent reflectivity in theory this method can be successfully applied to find the orientation of dipping layers cylinders and vertical fractures modeling results show angle dependent reflections in all three cases as a result we can exactly determine the orientation of these targets analysis of a field survey at a controlled gpr test site in which reflections were collected from an elongate cylinder buried in a homogeneous soil show good prediction of the angle of orientation of the cylinder and confirm the expected theoretical and modeling results the alford rotation method requires accurate data acquisition for effective practical implementation improved results will require exact knowledge of the radiation pattern of the gpr antennas under different circumstances

modelling outburst floods from moraine dammed glacial lakes in response to climatic change the size and number of moraine dammed supraglacial and proglacial lake systems have increased dramatically in recent decades given an appropriate trigger the natural moraine dams that impound these proglacial lakes are breached producing catastrophic glacial lake outburst floods glofs these floods are highly complex phenomena with flood characteristics controlled in the first instance by the style of breach formation downstream glofs typically exhibit transient often non newtonian fluid dynamics as a result of high rates of sediment entrainment from the dam structure and channel boundaries combined these characteristics introduce numerous modelling challenges in this review the historical contemporary and emerging approaches available to model the individual stages or components of a glof event are introduced and discussed a number of methods exist to model the stages of a glof event dam breach models can be categorised as being empirical analytical or numerical in nature with each method having significant advantages and shortcomings empirical relationships that produce estimates of peak discharge and time to peak are straightforward to implement but the applicability of these models is often limited by the nature of the case study data from which they are derived furthermore empirical models neglect the inclusion of basic hydraulic principles that describe the mechanics of breach formation analytical or parametric models simulate breach development using simplified versions of the physically based equations that describe breach enlargement whilst complex physically based codes represent the state of the art in numerical dam breach modelling to date few of the latter have been applied to investigate the moraine dam failure problem despite significant advances in the physical complexity and availability of higher order hydrodynamic solvers the majority of published accounts that have attempted to reconstruct or predict glof characteristics have been limited often by necessity to the use of relatively simplistic models this is in part attributable to the unavailability of terrain models of many high mountain catchments at the fine spatial resolutions required for the effective application of numerically sophisticated codes and their proprietary and often cost prohibitive nature however advanced models are experiencing increasing use in the glacial hazards literature in particular the suitability of emerging mesh free particle based methods for simulating dam breach and glof routing may represent a solution to many of the challenges associated with modelling this complex phenomenon sources of uncertainty in the glof modelling chain have been identified by various workers however to date their significance for the robustness of reconstructive and predictive modelling efforts have been largely unexplored and quantified in detail these sources include the geometric and material characterisation of moraine dam complexes including lake bathymetry and the presence and extent of buried ice initial conditions freeboard precise spillway dimensions spatial discretisation of the down valley domain hydrodynamic model dimensionality and the dynamic coupling of successive components in the glof model cascade

a spatially resolved estimate of high mountain asia glacier mass balances from 2000 to 2016 glacier mass balances in high mountain asia are uncertain satellite stereo imagery allows a spatially resolved estimate for about 92 of the glacierized area and yields a region wide average of about 16 gt yr 1 for 2000 to 2016

vertical fracture detection by exploiting the polarization properties of ground penetrating radar signals vertically oriented thin fractures are not always detected by conventional single polarization reflection profiling ground penetrating radar gpr techniques we study the polarization properties of em wavefields and suggest multipolarization acquisition surveying to detect the location and azimuth of vertically oriented fractures we employ analytical solutions 3d finitedifference time domain modeling and field measurements of multipolarization gpr data to investigate em wave transmission through fractured geologic formations for surface based multipolarization gpr measurements across vertical fractures we observe a phase lead when the incident electric field component is oriented perpendicular to the plane of the fracture this observation is consistent for nonmagnetic geologic environments and allows the determination of vertical fracture location and azimuth based on the presence of a phase difference and a phase lead relationship between varying polarization gpr data

massive collapse of two glaciers in western tibet in 2016 after surge like instability surges and glacier avalanches are expressions of glacier instability and among the most dramatic phenomena in the mountain cryosphere until now the catastrophic collapse of a glacier combining the large volume of surges and mobility of ice avalanches has been reported only for the 2002 130 106 m3 detachment of kolka glacier caucasus mountains which has been considered a globally singular event here we report on the similar detachment of the entire lower parts of two adjacent glaciers in western tibet in july and september 2016 leading to an unprecedented pair of giant low angle ice avalanches with volumes of 68 2 106 m3 and 83 2 106 m3 on the basis of satellite remote sensing numerical modelling and field investigations we find that the twin collapses were caused by climate and weather driven external forcing acting on specific polythermal and soft bed glacier properties these factors converged to produce surge like enhancement of driving stresses and massively reduced basal friction connected to subglacial water and fine grained bed lithology to eventually exceed collapse thresholds in resisting forces of the tongues frozen to their bed our findings show that large catastrophic instabilities of low angle glaciers can happen under rare circumstances without historical precedent two catastrophic glacier collapse events in western tibet in 2016 were caused by a convergence of weather and glacier bed conditions according to an analysis of observations and modelling

which dem is best for analyzing fluvial landscape development in mountainous terrains abstract regional studies of fluvial landforms and long term quaternary landscape development in remote mountain landscapes routinely use satellite derived dem data sets the srtm and aster dems are the most commonly utilised because of their longer availability free cost and ease of access however rapid technological developments mean that newer and higher resolution dem data sets such as alos world 3d aw3d and tandem x are being released to the scientific community geomorphologists are thus faced with an increasingly problematic challenge of selecting an appropriate dem for their landscape analyses here we test the application of four medium resolution dem products 30 m srtm aster aw3d 12 m tandem x for qualitative and quantitative analysis of a fluvial mountain landscape using the dades river catchment high atlas mountains morocco this landscape comprises significant dem remote sensing challenges notably a high mountain relief steep slopes and a deeply incised high sinuosity drainage network with narrow canyon gorge reaches our goal was to see which dem produced the most representative best fit drainage network and meaningful quantification to achieve this we used arcgis and stream profiler platforms to generate catchment hillshade and slope rasters and to extract drainage network channel long profile and channel slope and area data tandem x produces the clearest landscape representation but with channel routing errors in localised high relief areas thirty metre dems are smoother and less detailed but the aw3d shows the closest fit to the real drainage network configuration the tandem x elevation values are the closest to field derived gps measurements long profiles exhibit similar shapes but with minor differences in length elevation and the degree of noise smoothing with aw3d producing the best representation slope area plots display similarly positioned slope break knickpoints with modest differences in steepness and concavity indices but again best represented by aw3d collectively our study shows that despite the higher effective resolution of tandem x 12 m the aw3d 30 m data performs strongly across all analyses suggesting that it currently offers the greatest potential for regional mountain geomorphological analyses

observations of dune interactions from dems using through water structure from motion abstract the role of three dimensionality 3d in modulating both flow and sediment transport remains poorly understood 3d bed elevation measurements are difficult to obtain due to irregular dune shapes and submergence using photogrammetric tools for topographic reconstruction has become popular in surface studies yet water refraction makes through water image capturing of submerged dunes still challenging we show that through water images and structure from motion sfm tools can produce accurate digital elevation models dems of a measured dune field with a high level of detail it is a low cost and non intrusive alternative for submerged bed elevation measurements we provide a detailed sfm workflow introduce and discuss the use of camera coordinates and underwater ground control points and processing steps needed to obtain high accuracy dems our method results in dems with mm resolution in controlled laboratory conditions new data for 23 dune field dems from 6 experiments were obtained and are presented the dune field dem time series provide insights on dune interaction processes in our experiments merging and defect creation were most common merging decreases the number of bedforms and defect creation is responsible for more bedforms dunes continue to interact and jostle after achieving equilibrium simple crests are much more frequently observed than irregular sinuous or double crests two dimensional 2d crest shapes were observed although crest shapes were generally of 3d nature observed dune migration rates are not steady and vary in time and space bedform splitting speeds up dune migration whilst neighbouring dunes tend to accelerate or decelerate we identify a cascade of processes and show that 3d dems at high frequency are required to resolve observed rapid deformations and interaction of dunes the identified dune interaction processes are inherent to sediment flux variability whereas the temporal component of the underlying sediment transport processes is still not well understood in relation to average transport

which fractures are imaged with ground penetrating radar results from an experiment in the aspo hardrock laboratory sweden abstract identifying fractures in the subsurface is crucial for many geomechanical and hydrogeological applications here we assess the ability of the ground penetrating radar gpr method to image open fractures with sub mm apertures in the context of future deep disposal of radioactive waste gpr experiments were conducted in a tunnel located 410 m below sea level within the aspo hard rock laboratory sweden using 3 d surface based acquisitions 3 4 m 19 m with 160 mhz 450 mhz and 750 mhz antennas the nature of 17 identified gpr reflections was analyzed by means of three new boreholes bh1 bh3 9 9 5 m deep out of 21 injection and outflow tests in packed off 1 m sections only five provided responses above the detection threshold with the maximum transmissivity reaching 7 0 10 10 m2 s most gpr reflections are situated in these permeable regions and their characteristics agree well with core and optical televiewer data a 3 d statistical fracture model deduced from fracture traces on neighboring tunnel walls show that the gpr data mainly identify fractures with dips between 0 and 25 since the gpr data are mostly sensitive to open fractures we deduce that the surface gpr method can identify 80 of open sub horizontal fractures we also find that the scaling of gpr fractures in the range of 1 10 m2 agrees well with the statistical model distribution indicating that fracture lengths are preserved by the gpr imaging no measurement bias our results suggests that surface gpr carries the resolution needed to identify the most permeable sub horizontal fractures even in very low permeability formations thereby suggesting that surface gpr could play an important role in geotechnical workflows for instance for industrial scale siting of waste canisters below tunnel floors in nuclear waste repositories

impact of a rock avalanche on a moraine dammed proglacial lake laguna safuna alta cordillera blanca peru hubbard bryn heald a reynolds j quincey d 2005 impact of a rock avalanche on a moraine dammed proglacial lake laguna safuna alta cordillera blanca peru earth surface processes and landforms 30 10 pp 1251 1264 rae2008

visualization of active faults using geometric attributes of 3d gpr data an example from the alpine fault zone new zealand three dimensional ground penetrating radar gpr data are routinely acquired for diverse geologic hydrogeologic archeological and civil engineering purposes interpretations of these dataareinvariablybasedonsubjectiveanalysesofreflectionpatterns such analyses are heavily dependent on interpreter expertiseandexperience usingdataacquiredacrossgravelunitsoverlyingthealpinefaultzoneinnewzealand wedemonstratethe utilityofvariousgeometricattributesinreducingthesubjectivity of3dgprdataanalysis weuseacoherence basedtechniqueto compute the coherency azimuth and dip attributes and a graylevel co occurrence matrixglcmmethod to compute the texture basedenergy entropy homogeneity andcontrastattributes a selection of the gpr attribute volumes allows us to highlight key aspects of the fault zone and observe important features not apparent in the standard images this selection also provides information that improves our understanding of gravel deposition andtectonicstructuresatthestudysite anewdepositional structuralmodellargelybasedontheresultsofouranalysisofgprattributes includes four distinct gravel units deposited in three phases and a well defined fault trace this fault trace coincides with a zone of stratal disruption and shearing bound on one side by upward tilted to synclinally folded stratified gravels and on the other side by moderately dipping stratified alluvial fan gravelsthatcouldhavebeenaffectedbylateralfaultdrag whenused in tandem the coherence and texture based attribute volumes can significantly improve the efficiency and quality of 3d gpr interpretation especially for complex data collected across activefaultzones

multiconfiguration gpr measurements for geometric fracture characterization in limestone cliffs alps rock mass fracturing is a key parameter in rock fall hazard assessment however traditional geologic observations can provide information only about discontinuities at the surface in this case study detailed ground penetrating radar gpr measurements with antennas of 50 mhz 100 mhz 200 mhz and 400 mhz were conducted on a test site using different acquisition configurations deployed on vertical cliff faces conventional 2d profile data common midpoint cmp survey data and transmission data were acquired to evaluate the potential use of radar waves to characterize the geometry and properties of the major discontinuities fractures within a mesozoic limestone massif results showed that the continuity and geometry orientation and dip of the major observed fractures which are crucial parameters for assessing rock stability can be obtained by combining vertical and horizontal profiles measured along the cliff we used 100 mhz antennae and reached a maximum penetration of 20 m which limi

multicomponent georadar data some important implications for data acquisition and processing many seismic reflection processing techniques are applied routinely to ground penetrating radar georadar or gpr data although similarities exist between seismic acoustic and radar wave propagation there are some significant differences some of the most important of which are associated with the dipole nature 1 of georadar sources and receivers and 2 of elemental sources used to represent scattering bodies neglecting the dipole character of electromagnetic surveys may result in incomplete or biased images of the subsurface in an attempt to understand better the consequences of recording dipolar wavefields we have simulated numerous multicomponent georadar data sets these simulations are based on the weak scattering born approximation such that point heterogeneities in the subsurface can be represented by infinitesimal dipoles with moments parallel and proportional to the incident georadar wavefields the effects of depolarization and dispersion are not included nevertheless many subsurfa

combination of h alpha decomposition and migration for enhancing subsurface target classification of gpr polarimetric technology has been one of the most important advances in microwave remote sensing during recent decades h alpha decomposition which is a type of polarimetric analysis technique has been common for terrain and land use classification in polarimetric synthetic aperture radar however the technique has been less common in the ground penetrating radar gpr community in this paper we apply the h alpha decomposition to analyze the surface gpr data to obtain polarimetric attributes for subsurface target classification also by combining h alpha decomposition and migration we can obtain a subsurface h alpha color coded reconstructed target image from which we can use both the polarimetric attributes and the geometrical features of the subsurface targets to enhance the ability of subsurface target classification of surface gpr a 3 d full polarimetric gpr data set was acquired in a laboratory experiment in which four targets a scatterer with many branches a ball a plate and a dihedral scatter were buried in dry sand under flat ground surface and used to test these techniques as results we obtained the subsurface h alpha distribution and classified the subsurface targets also we derived a subsurface h alpha color coded reconstructed target image and identified all four targets in the laboratory experiment

one dimensional modeling of dam break flow over movable beds a one dimensional model has been established to simulate the fluvial processes under dam break flow over movable beds the hydrodynamic model adopts the generalized shallow water equations which consider the effects of sediment transport and bed change on the flow the sediment model computes the nonequilibrium transport of bed load and suspended load the effects of sediment concentration on sediment settling and entrainment are considered in determining the sediment settling velocity and transport capacity in particular a correction factor is proposed to modify the van rijn formulas of equilibrium bed load transport rate and near bed suspended load concentration for the simulation of sediment transport under high shear flow conditions the governing equations are solved by an explicit finite volume method with the first order upwind scheme for intercell fluxes the model has been tested in two experimental cases with fairly good agreement between simulations and measurements the sensitivities of the model results to parameters such as the sediment nonequilibrium adaptation length manning s roughness coefficient and the proposed correction factor have been verified the proposed model has also been compared to an existing model and the results indicate the new model is more reliable

diffraction imaging of sub vertical fractures and karst with full resolution 3d ground penetrating radar abstract vertical fractures with openings of less than one centimetre and irregular karst cause abundant diffractions in ground penetrating radar gpr records gpr data acquired with half wavelength trace spacing are uninterpretable as they are dominated by spatially undersampled scattered energy to evaluate the potential of high density 3d gpr diffraction imaging a 200 mhz survey with less than a quarter wavelength grid spacing 0 05 m 0 1 m was acquired at a fractured and karstified limestone quarry near the village of cassis in southern france after 3d migration processing diffraction apices line up in sub vertical fracture planes and cluster in locations of karstic dissolution features the majority of karst is developed at intersections of two or more fractures and is limited in depth by a stratigraphic boundary such high resolution 3d gpr imaging offers an unprecedented internal view of a complex fractured carbonate reservoir model analogue as seismic and gpr wave kinematics are similar improvements in the imaging of steep fractures and irregular voids at the resolution limit can also be expected from high density seismic diffraction imaging

3 d seismic discontinuity for faults and stratigraphic features the coherence cube seismic data are usually acquired and processed for imaging reflections this paper describes a method of processing seismic data for imaging discontinuities e g faults and stratigraphic features one application of this nontraditional process is a 3 d volume or cube of coherence coefficients within which faults are revealed as numerically separated surfaces figure 1 compares a traditional 3 d reflection amplitude time slice with the results of the new method to our knowledge this is the first published method of revealing fault surfaces within a 3 d volume for which no fault reflections have been recorded

four dimensional mapping of tracer channelization in subhorizontal bedrock fractures using surface ground penetrating radar 1 to observe flow channeling in situ surface ground penetrating radar gpr was used to detect a saline tracer moving through a sub horizontal bedrock fracture the tracer is mapped using amplitude variations resulting from the significant difference in electromagnetic properties between the tracer and natural ground water within the fracture results show that hydrogeophysical investigations using gpr can successfully image tracer movement in a variety of flow configurations in three spatial dimensions through time hence 4d observed tracer travel paths demonstrated meter scale spatial variability that may be attributed to heterogeneity in fracture aperture

discovery of a large brine deep in the northern red sea the red sea is formed of marginal areas shallower than 1 000 m which are separated by a deeper axial zone the axial zone can be subdivided into three main segments the southern segment is a relatively simple trough which north of 16 n corresponds to an oceanic rift1 the middle segment from 19 30 n to 23 50 n is characterized by the presence of about 15 closed depressions or axial deeps ranging from several kilometres to less than a kilometre in length and containing hot of cold brines underlain by their associated deposits of soft and fine grained metalliferous muds1 3 the northern segment of the axial zone is shallower with depths rarely exceeding 1 500 m and has a smoother relief than the southern and central segments in the northern segments south of the al wajh depression at 25 25 n the axis strikes north south fig 1 north of the depression towards the approaches of the gulf of suez the strike is nnw sse the small circular 1 km diameter oceanographer deep is located4 along the western border of the axial zone of this northernmost segment the jean charcot deep which we discovered on 3 december 1983 during a cruise of the rv jean charcot lies near 25 15 n 35 22 e close to the axis of maximum depth of the same segment in contrast with the magnetically quiet neighbourhood a strong dipolar magnetic anomaly typifies this deep which in spite of intensive international surveys is the first brine deep to have been discovered in the red sea in the past 10 years

classification of slope processes based on multitemporal dinsar analyses in the himalaya of nw bhutan abstract slope deformation in mountainous terrain can be driven by different processes the nature of which is either gravitational and irreversible or seasonal and reversible the latter induced by permafrost variations or by hydromechanical or thermomechanical effects the importance of identifying such deformations is not only related to the hazard they can pose but also to the understanding of changes that permafrost or local hydrological conditions undergo here we carry out a multi temporal insar analysis over a mountainous area 8000 km2 large straddling north western bhutan and southern tibet we propose a methodology to separate locally deforming areas from the effects of long wavelength signals through the analysis of the spatio temporal behaviour of 4 years long time series of surface displacements we present the mapping of hundreds of small scale features that appear to be actively deforming as well as several examples of reversible deformation rarely detected at this scale in such a challenging and vast region the analysis of the multi annual trend of ground deformation shows a relatively small number of irreversible gravitational movements clearly related to rock slides which attests a low level of recent activity of large rock slope instabilities in the region in the southernmost lower elevation parts of the study area we quantify reversible surface displacements with amplitudes ranging between 5 and 17 mm and showing maximum displacements towards the satellite in summer months thus compatible with hydro mechanical effects related to groundwater table variations in addition the ground movement induced by the active layer s response to thawing and freezing over the gentler slopes and high elevation permafrost regions of bhutan and southern tibet is on average around 10 mm with maxima up to 28 mm the localised displacements appear to be largely associated to braided stream plains glacier outwash plains or low angle fine sediment covered slopes

structure from motion photogrammetry a low cost effective tool for geoscience applications abstract high resolution topographic surveying is traditionally associated with high capital and logistical costs so that data acquisition is often passed on to specialist third party organisations the high costs of data collection are for many applications in the earth sciences exacerbated by the remoteness and inaccessibility of many field sites rendering cheaper more portable surveying platforms i e terrestrial laser scanning or gps impractical this paper outlines a revolutionary low cost user friendly photogrammetric technique for obtaining high resolution datasets at a range of scales termed structure from motion sfm traditional softcopy photogrammetric methods require the 3 d location and pose of the camera s or the 3 d location of ground control points to be known to facilitate scene triangulation and reconstruction in contrast the sfm method solves the camera pose and scene geometry simultaneously and automatically using a highly redundant bundle adjustment based on matching features in multiple overlapping offset images a comprehensive introduction to the technique is presented followed by an outline of the methods used to create high resolution digital elevation models dems from extensive photosets obtained using a consumer grade digital camera as an initial appraisal of the technique an sfm derived dem is compared directly with a similar model obtained using terrestrial laser scanning this intercomparison reveals that decimetre scale vertical accuracy can be achieved using sfm even for sites with complex topography and a range of land covers example applications of sfm are presented for three contrasting landforms across a range of scales including an exposed rocky coastal cliff a breached moraine dam complex and a glacially sculpted bedrock ridge the sfm technique represents a major advancement in the field of photogrammetry for geoscience applications our results and experiences indicate sfm is an inexpensive effective and flexible approach to capturing complex topography

the second chinese glacier inventory data methods and results the second chinese glacier inventory was compiled based on 218 landsat tm etm scenes acquired mainly during 2006 10 the widely used band ratio segmentation method was applied as the first step in delineating glacier outlines and then intensive manual improvements were performed the shuttle radar topography mission digital elevation model was used to derive altitudinal attributes of glaciers the boundaries of some glaciers measured by real time kinematic differential gps or digitized from high resolution images were used as references to validate the accuracy of the methods used to delineate glaciers which resulted in positioning errors of 10 m for manually improved clean ice outlines and 30 m for manually digitized outlines of debris covered parts the glacier area error of the compiled inventory evaluated using these two positioning accuracies was 3 2 the compiled parts of the new inventory have a total area of 43 087 km 2 in which 1723 glaciers were covered by debris with a total debris covered area of 1494 km 2 the area of uncompiled glaciers from the digitized first chinese glacier inventory is similar to 8753 km 2 mainly distributed in the southeastern tibetan plateau where no images of acceptable quality for glacier outline delineation can be found during 2006 10

floods in mountain environments a synthesis floods are a crucial agent of geomorphic change in the channels and valley floors of mountains watercourses at the same time they can be highly damaging to property infrastructure and life because of their high energy mountain watercourses are highly vulnerable to environmental changes affecting their catchments and channels many factors have modified and frequently still tend to modify the environmental conditions in mountain areas with impacts on geomorphic processes and the frequency magnitude and timing of floods in mountain watercourses the ongoing climate changes vary between regions but may affect floods in mountain areas in many ways in many mountain regions of europe widespread afforestation took place over the twentieth century considerably increasing the amounts of large wood delivered to the channels and the likelihood of jamming bridges at the same time deforestation continues in other mountain areas accelerating runoff and amplifying the magnitude and frequency of floods in foreland areas in many countries in channel gravel mining has been a common practice during recent decades the resultant deficit of bed material in the affected channels may suddenly manifest during flood events resulting in the failure of scoured bridges or catastrophic channel widening during the past century many rivers in mountain and foreland areas incised deeply the resultant loss of floodplain water storage has decreased attenuation of flood waves hence increasing flood hazard to downstream river reaches on the other hand a large amount of recent river restoration activities worldwide may provide examples of beneficial changes to flood risk attained as a result of increased channel storage or reestablished floodplain water storage relations between geomorphic processes and floods operate in both directions which means that changes in flood probability or the character of floods e g increased wood load may significantly modify the morphology of mountain rivers but morphological changes of rivers can also affect hydrological properties of floods and the associated risk for societies this paper provides a review of research in the field of floods in mountain environments and puts the papers of this special issue dedicated to the same topic into context it also provides insight into innovative studies methods or emerging aspects of the relations between environmental changes geomorphic processes and the occurrence of floods in mountain rivers

3d polarimetric gpr coherency attributes and full waveform inversion of transmission data for characterizing fractured rock ground penetrating radar gpr can detect and describe fractures to help us characterize fractured rock formations a fracture alters the incident waveform or wave shape of a gpr signal through constructive and destructive interference depending on the aperture fill and orientation of the fracture because the electromagnetic em waves of gpr are vectorial features exhibiting strong directionality can change the state of polarization of the incident field gpr methods that focus on changes in waveform or polarization can improve detection and discrimination of fractures within rock bodies an algorithm based on coherency a seismic attribute that delineates discontinuities in wavelet shape is developed for polarimetric gpr it uses the largest eigenvalue of the time domain scattering matrix when calculating coherence this algorithm is sensitive to wave shape and is unbiased by the polarization of gpr antennas polarimetric coherency works better than scalar coherency in removing the effects of polarization on field data collected from a fractured limestone plot used for hydrologic experimentation another method for time domain full waveform inversion of transmission data quantitatively determines fracture aperture and em properties of fill based on a thin layer model inversion results from field data show consistency with the location of fractures from reflection data these two methods offer better fracture detection capability and quantitative information on fracture aperture dielectric permittivity and electrical conductivity of the fill than traditional gpr imaging and scalar coherency attributes

texture attribute analysis of gpr data for archaeological prospection we evaluate the applicability and the effectiveness of texture attribute analysis of 2 d and 3 d gpr datasets obtained in different archaeological environments textural attributes are successfully used in seismic stratigraphic studies for hydrocarbon exploration to improve the interpretation of complex subsurface structures we use a gray level co occurrence matrix glcm algorithm to compute second order statistical measures of textural characteristics such as contrast energy entropy and homogeneity textural attributes provide specific information about the data and can highlight characteristics as uniformity or complexity which complement the interpretation of amplitude data and integrate the features extracted from conventional attributes the results from three archaeological case studies demonstrate that the proposed texture analysis can enhance understanding of gpr data by providing clearer images of distribution volume and shape of potential archaeological targets and related stratigraphic units particularly in combination with the conventional gpr attributes such strategy improves the interpretability of gpr data and can be very helpful for archaeological excavation planning and more generally for buried cultural heritage assessment

investigating multi polarization gpr wave transmission through thin layers implications for vertical fracture characterization this is the published version copyright 2006 american geophysical union all rights reserved

full resolution 3d gpr imaging noninvasive 3d ground penetrating radar gpr imaging with submeter resolution in all directions delineates the internal architecture and processes of the shallow subsurface full resolution imaging requires unaliased recording of reflections and diffractions coupled with 3d migration processing the gpr practitioner can easily determine necessary acquisition trace spacing on a frequency wavenumber f k plot of a representative 2d gpr test profile quarter wavelength spatial sampling is a minimum requirement for full resolution gpr recording an intensely fractured limestone quarry serves as a test site for a 100 mhz 3d gpr survey with 0 1 m 0 2 m trace spacing this example clearly defines the geometry of fractures in four different orientations including vertical dips to a depth of 20 m decimation to commonly used half wavelength spatial sampling or only 2d migration processing makes most fractures invisible the extra data acquisition effort results in image volumes with submeter resolution both

an inventory of historical glacial lake outburst floods in the himalayas based on remote sensing observations and geomorphological analysis abstract glacial lake outburst floods glofs are a unique type of natural hazard in the cryosphere that may result in catastrophic fatalities and damages the himalayas are known as one of the world s most glof vulnerable zones effective hazard assessments and risk management require a thorough inventory of historical glof events across the himalayas which is hitherto absent existing studies imply that numerous historical glof events are contentious because of discrepant geographic coordinates names or outburst time requiring further verifications this study reviews and verifies over 60 historical glof events across the himalayas using a comprehensive method that combines literature documentations archival remote sensing observations geomorphological analysis and field investigations as a result three unreported glof events were discovered from remote sensing images and geomorphological analysis eleven suspicious events were identified and suggested to be excluded the properties of five outburst lakes i e degaco chongbaxia tsho geiqu lemthang tsho and a lake on tshojo glacier were corrected or updated a total of 51 glof events were verified to be convincing and these outburst lakes were classified into three categories according to their statuses in the past decades namely disappeared 12 stable 30 and expanding 9 statistics of the verified glof events show that glof tended to occur between april and october in the himalayas we suggest that more attention should be paid to rapidly expanding glacial lakes with high possibility of repetitive outbursts this study also demonstrates the effectiveness of integrating remote sensing and geomorphic interpretations in identifying and verifying glof events in remote alpine environments this inventory of glofs with a range of critical attributes e g locations time and mechanisms will benefit the continuous monitoring and prediction of potentially dangerous glacial lakes and contribute to outburst induced risk assessments and hazard mitigations