water balance observations reveal significant subsurface water seepage from lake nam co south central tibetan plateau summary hydrological observations including precipitation runoff evaporation and lake level were performed in detail in the basin of the lake nam co in the southern central tibetan plateau from 2007 to 2011 two runoff coefficients at differing catchment scales were obtained and applied to derive the surface water inflow to the lake from the non glaciated areas total runoff was partitioned into contributions from glaciated and non glaciated areas at two additional catchment scales the runoff from the non glaciated areas amounted to 1400 mm lake depth during the observation period from may 18 to october 17 2008 during which the most complete set of observations was obtained neglecting groundwater contributions this amount accounted for 55 65 of the total water input to the lake nam co the precipitation contribution and the meltwater inflow from the glaciers accounted for 23 28 and 7 22 of the total water input to the lake respectively the water input was found to be 810 1220 mm lake depth 1 63 109 2 47 109 m3 more than the output of the lake during a 5 month period in 2008 similar results were obtained for the years 2007 and 2009 2011 as there is no surface outflow from the lake the large water imbalance can only be explained by water seepage corresponding to an average outflow of 120 190 m3 s 1 or 5 8 mm lake water depth per day it is likely that the main pathway for lake water seepage is through the sub surface fault system which is known to exist in the area

flow characteristics of large eruption triggered debris flows at snow clad volcanoes constraints for debris flow models abstract theoretical modelling is not yet adequate to predict the behavior of debris flows which can be an extremely hazardous hydrologic process commonly associated with volcanic eruptions particularly at snow clad stratovolcanoes to provide a realistic basis for modelling the behavior of large 1000 m3 s debris flows this paper summarizes kinematic volumetric and hydraulic characteristics of ten large historic volcanic debris flows from four different volcanoes although debris flows larger than these are known to have occurred in the past the ten summarized here define a practical upper range in magnitude of more typical flows to be considered for future hazard prediction peak flow velocities of the ten debris flows studied were indirectly measured to be between about 5 and 20 m s on gradients of 0 005 to 0 25 m m but locally they were as great as 40 m s hydraulic average depths were as great as 25 m but were more commonly between 5 and 15 m in channels up to 400 m wide computed peak discharges volumetric flow rates were as high as 105 m3 s and total volumes were as much as 108 m3 total flow volumes increased by as much as four times in relatively steep channels as eroded sediment was incorporated into the debris flows flows generally achieved supercritical flow and deposited minimal volumes of sediment on gradients steeper than 0 02 m m subcritical flow and active deposition predominated on gradients less than 0 01 m m although flows travelled tens of kilometers on such low gradients while laying down deposits total distances travelled as debris flows were as far as 120 km

lake volume and groundwater storage variations in tibetan plateau s endorheic basin the tibetan plateau tp the highest and largest plateau in the world with complex and competing cryospheric hydrologic geodynamic processes is particularly sensitive to anthropogenic warming the quantitative water mass budget in the tp is poorly known here we examine annual changes in lake area level and volume during 1970s 2015 we find that a complex pattern of lake volume changes during 1970s 2015 a slight decrease of 2 78 gt yr 1 during 1970s 1995 followed by a rapid increase of 12 53 gt yr 1 during 1996 2010 and then a recent deceleration 1 46 gt yr 1 during 2011 2015 we then estimated the recent water mass budget for the inner tp 2003 2009 including changes in terrestrial water storage lake volume glacier mass snow water equivalent swe soil moisture and permafrost the dominant components of water mass budget namely changes in lake volume 7 72 0 63 gt yr 1 and groundwater storage 5 01 1 59 gt yr 1 increased at similar rates we find that increased net precipitation contributes the majority of water supply 74 for the lake volume increase followed by glacier mass loss 13 and ground ice melt due to permafrost degradation 12 other term such as swe 1 makes a relatively small contribution these results suggest that the hydrologic cycle in the tp has intensified remarkably during recent decades

discontinuous precipitation of rutilated quartz grain boundary migration induced by changes to the equilibrium solubility of ti in quartz we experimentally investigated changes to the titanium concentrations of quartz rich rocks caused by grain boundary migration synthesis experiments were performed to make high ti quartz starting materials for usage in recrystallization experiments we isothermally recrystallized quartz starting material in separate experiments at 10 25 kbar to reduce the solubility of ti in quartz microstructural and geochemical results indicate that the high ti quartz starting material recrystallized to form low ti quartz with acicular rutile inclusions during recrystallization high ti quartz was consumed to form low ti quartz and acicular rutile crystals precipitated behind moving grain boundaries via the discontinuous precipitation unmixing process experimentally imposed changes to the equilibrium solubility concentration of ti in quartz by amounts as low as 0 02 weight 200 g g or ppm by weight created a free energy driving force of 8 7 kj mol that was sufficient to drive large scale recrystallization of the quartzites microstructures of relict grains of the high ti quartz starting materials are characterized by cuspate and irregular grain boundaries whereas new quartz grains exhibit subhedral to euhedral grain morphologies and abundant three grain junctions discontinuous precipitation can significantly change mineral compositions and in the absence of a free fluid phase can operate much faster than other types of mass transfer processes commonly associated with solid state reactions

two dimensional water flood and mudflow simulation flo 2d is a two dimensional finite difference model that simulates clear water flood hazards mudflows and debris flows on alluvial fans and urban floodplains interactive flood or mudflow routing between channel street and floodplain flow is performed using a uniform grid system to describe complex floodplain topography a quadratic rheological model developed from field and laboratory mudflow data enables appropriate simulations of flooding conditions ranging from clear water to hyperconcentrated sediment flows computer aided design cad graphics of predicted time sequenced flood depths automates the delineation of flood hazards replication of the 1983 rudd creek mudflow in utah demonstrates the capability of the model

the role of the sediment budget in understanding debris flow susceptibility this study proposes a sediment budget model to predict the temporal variation of debris volume stored in a debris flow prone watershed the sediment budget is dominated by shallow landslides and debris outflow the basin topography and the debris volume stored in the source area of the debris flow prone watershed help evaluating its debris flow susceptibility the susceptibility model is applied to the tungshih area of central western taiwan the importance of the debris volume in predicting debris flow susceptibility is reflected in the standardized coefficients of the proposed statistical discriminant model the high prediction rate 0 874 for the occurrence of debris flows justifies the capability of the proposed susceptibility models to predict the occurrence of debris flows this model is then used to evaluate the temporal evolution of the debris flow susceptibility index the analysis results show that the numbers of watershed which are classified as a debris flow group correspond well to storage of sediment at different time periods these numbers are 10 before the occurrence of chi chi earthquake 13 after the occurrence of chi chi earthquake 16 after the occurrence of landslides induced by typhoon mindulle typhoon m and 14 after the occurrence of debris flows induced by typhoon m it indicates that the occurrence of 7 6 chi chi earthquake had significant impact on the debris flow occurrence during subsequent typhoons copyright 2009 john wiley sons ltd

simulation and analysis of glacier runoff and mass balance in the nam co basin southern tibetan plateau runoff estimation in high altitude glacierized basins is an important issue on the tibetan plateau to investigate glacier mass balance runoff and water balance in the qugaqie basin and zhadang sub basin in the southern tibetan plateau two glacier models and three snow models were integrated into the spatially distributed hydrological model jams j2k the results showed that the temperature index method simulated glacier runoff better than the degree day factor method the simulated glacier melt volume in the qugaqie basin in 2006 2007 and 2008 contributed 58 50 and 41 respectively to its total runoff in the zhadang basin the glacier melt volume contributed 78 and 66 to its runoff during 2007 and 2008 respectively compared with the observation results the simulated glacier mass balance showed similar variations with slightly higher values indicating an underestimation of glacier melt volume the water balance simulation in the upstream areas 705 874 mm was comparable to that in the downstream areas 1051 1502 mm and generally lower than the observed results in both basins the glacier mass balance simulation was relatively accurate in the melt season compared to the other seasons

flow of variably fluidized granular masses across three dimensional terrain 2 numerical predictions and experimental tests numerical solutions of the equations describing flow of variably fluidized coulomb mixtures predict key features of dry granular avalanches and water saturated debris flows measured in physical experiments these features include time dependent speeds depths and widths of flows as well as the geometry of resulting deposits three dimensional 3 d boundary surfaces strongly influence flow dynamics because transverse shearing and cross stream momentum transport occur where topography obstructs or redirects motion consequent energy dissipation can cause local deceleration and deposition even on steep slopes velocities of surge fronts and other discontinuities that develop as flows cross 3 d terrain are predicted accurately by using a riemann solution algorithm the algorithm employs a gravity wave speed that accounts for different intensities of lateral stress transfer in regions of extending and compressing flow and in regions with different degrees of fluidization field observations and experiments indicate that flows in which fluid plays a significant role typically have high friction margins with weaker interiors partly fluidized by pore pressure interaction of the strong perimeter and weak interior produces relatively steep sided flat topped deposits to simulate these effects we compute pore pressure distributions using an advection diffusion model with enhanced diffusivity near flow margins although challenges remain in evaluating pore pressure distributions in diverse geophysical flows riemann solutions of the depth averaged 3 d coulomb mixture equations provide a powerful tool for interpreting and predicting flow behavior they provide a means of modeling debris flows rock avalanches pyroclastic flows and related phenomena without invoking and calibrating rheological parameters that have questionable physical significance

groundwater storage changes in the tibetan plateau and adjacent areas revealed from grace satellite gravity data abstract understanding groundwater storage gws changes is vital to the utilization and control of water resources in the tibetan plateau however well level observations are rare in this big area and reliable hydrology models including gws are not available we use hydro geodesy to quantitate gws changes in the tibetan plateau and surroundings from 2003 to 2009 using a combined analysis of satellite gravity and satellite altimetry data hydrology models as well as a model of glacial isostatic adjustment gia release 5 grace gravity data are jointly used in a mascon fitting method to estimate the terrestrial water storage tws changes during the period from which the hydrology contributions and the gia effects are effectively deducted to give the estimates of gws changes for 12 selected regions of interest the hydrology contributions are carefully calculated from glaciers and lakes by icesat 1 satellite altimetry data permafrost degradation by an active layer depth ald model soil moisture and snow water equivalent by multiple hydrology models and the gia effects are calculated with the new ice 6g c vm5a model taking into account the measurement errors and the variability of the models the uncertainties are rigorously estimated for the tws changes the hydrology contributions including gws changes and the gia effect for the first time we show explicitly separated gws changes in the tibetan plateau and adjacent areas except for those to the south of the himalayas we find increasing trend rates for eight basins 2 46 2 24 gt yr for the jinsha river basin 1 77 2 09 gt yr for the nujiang lancangjiang rivers source region 1 86 1 69 gt yr for the yangtze river source region 1 14 1 39 gt yr for the yellow river source region 1 52 0 95 gt yr for the qaidam basin 1 66 1 52 gt yr for the central qiangtang nature reserve 5 37 2 17 gt yr for the upper indus basin and 2 77 0 99 gt yr for the aksu river basin all these increasing trends are most likely caused by increased runoff recharges from melt water and or precipitation in the surroundings we also find that the administrative actions such as the chinese ecological protection and construction project help to store more groundwater in the three rivers source region and suggest that seepages from the endorheic basin to the west of it are a possible source for gws increase in this region in addition our estimates for gws changes basically confirm previous results along afghanistan pakistan north india and bangladesh and clearly reflect the excessive use of groundwater our results will benefit the water resource management in the study area and are of particular significance for the ecological restoration in the tibetan plateau

rising springs along the silk road despite its extreme aridity the hexi corridor in northwestern china part of the ancient silk road has recently been repeatedly flooded by rising springs forcing 1000 families to abandon homes here we use new isotopic and chemical data for waters collected from the corridor and the qilian mountains to investigate the cause of the rising springs the data show that the springs may have originated from the mountain slopes where glacier melt mixes with the precipitation from a local convective system between the extensively irrigated hexi corridor and the qilian mountains accelerated glacier melting may have increased recharge of groundwater in the qilian mountains that was subsequently released by recent earthquakes from the mountains to the valley to raise the local water table the result has potential implications for the impact of climate change on water resources and management in arid regions

a comparison of pyroclastic flow and debris avalanche mobility many pyroclastic flows have runout distances longer than expected from basic frictional arguments in these cases the ratio of the height descended h and the runout l are as small as 0 2 a feature which has been attributed to fluidization however significant fluidization by gases is now considered unlikely during emplacement of debris avalanches where h l and volume are inversely related we determine whether pyroclastic flows are more mobile than debris avalanches of the same volume and if different emplacement mechanisms are needed to describe their runout h l and volume data were compiled for 34 nonvolcanic and 40 volcanic debris avalanche deposits as well as 15 pyroclastic flow deposits systematic differences in the volume versus h l plots were explored by statistical analysis results show an inverse relationship between h l and volume for both nonvolcanic and volcanic debris avalanche deposits as expected and also for pyroclastic flow deposits regression lines for plots of pyroclastic flow and volcanic debris avalanche data are statistically indistinguishable and the non volcanic debris avalanche line is parallel to the other two we argue that the nonvolcanic and volcanic debris avalanche differences are due to material properties rather than emplacement mechanisms therefore since pyroclastic flows and volcanic debris avalanches have indistinguishable h l versus volume it is unlikely that pyroclastic flows have a significantly different primary emplacement mechanism based on the data in hand we conclude that it is unnecessary to invoke gas fluidization to explain the mobility of the types of pyroclastic flows examined or the excess runout of large volume debris avalanches

the angle of reach as a mobility index for small and large landslides the relations between the angle of reach fahrboschung and other indexes expressing the mobility of landslides and vertical drop horizontal reach and volume of landslide mass have been analyzed by means of simplified plots and regression equations results for 204 landslides of all sizes show that whatever the mechanism of motion all kinds of landslides experience a continuous reduction of the angle of reach with volume increase this reduction starts from the smallest sizes scattering in this relation is mostly due to mechanisms of motion and to both obstacles and topographic constraints on the path this synthesis indicates that small landslides less than 0 5 106 m3 in relative terms display excesses of travel distance similar to large landslides since most small landslides are not expected to develop any change in the mechanism of progression while moving the decrease in the reach angle with volume suggests that scale effects should be taken into account the angle of reach is found to be

estimation of lakes water storage and their changes on the northwestern tibetan plateau based on bathymetric and landsat data and driving force analyses abstract lake water storage changes in four lakes were analyzed based on in situ bathymetric survey data and landsat images in the extremely dry and cold northwestern tibetan plateau region the results indicated that bangdag co and aksai chin lake which are glacier fed and closed lakes showed decreasing trends from 1976 to 1996 then increasing trend from 1996 to 2015 during which period water storage increased by 1 24 km3 and 1 37 km3 respectively and 65 of the water storage increase in aksai chin lake during this period occurring in 2006 and 2013 longmu co which is a non glacier fed lake exhibited little variation from 1976 to 1996 and a slight increase of 0 1 km3 from 1996 to 2015 the precipitation temperature and potential evaporation ep trends indicated that lake shrinkage from 1976 to 1996 was attributed to less precipitation and less meltwater at lower surface air temperatures decreased ep 15 5 mm y contributed approximately 2 and 4 to the lake expansion of aksai chin lake and bangdag co from 2000 to 2009 based on the assumption of equal precipitation evaporation for the study area glacial meltwater contributed 76 6 to the lake expansion of bangdag co from 2000 to 2015 because change in lakes water storage showed a large difference between glacier fed lakes and non glacier fed lakes from 1996 to 2015 under relatively high precipitation conditions it is suggested that glacial meltwater exerted more influence on increasing lake water storage associated with rising temperatures

triggering and predisposing factors for flow like landslides in pyroclastic soils the case study of the lattari mts southern italy abstract shallow flowslides debris flows and debris avalanches are rainfall induced landslides consisting in the shear failure of few metres of soils or in some cases even less than a metre which greatly increase downslope in volume and flow velocity the southern italian region of campania has been historically affected by such events involving pyroclastic soils mainly resting on steep carbonate slopes this paper deals with the analysis of factors influencing the occurrence of flow like landslides adopting the lattari mts in campania as a case study the results of two investigation campaigns carried out in the area allowed effective large scale geological and geotechnical characterization to be set up stratigraphic profiles mean physical properties and typical friction angles at the critical state for each soil layer were investigated the effect of suction on peak and critical shear strength whose drop is responsible for soil failure was analysed using detailed information on both the stratigraphic and geotechnical features of the soils involved in past flow like landslides typical triggering models were selected representing locally recurrent geomorphologic conditions at the basin scale the identified models were adopted for slope stability analyses carried out on four cross sections of flowslides occurring prior to the event to back analyse the triggering conditions from the evidence on the triggering mechanisms and the results of analyses the infinite slope approach is not always suitable to model slope stability conditions properly because the onset of landslides is also affected by local topographic and stratigraphic factors

quartz in garnet and ti in quartz thermobarometry methodology and first application to a quartzofeldspathic gneiss from eastern papua new guinea

debris flow release processes investigated through the analysis of multi temporal lidar datasets in north western iceland debris flows are fast moving gravity flows of poorly sorted rock and soil mixed and saturated with water debris flow initiation has been studied using empirical and experimental modelling but the geomorphic changes indicative of different triggering processes are difficult to constrain with field observations only we identify signatures to distinguish two different debris flow release styles by integrating high resolution multi temporal remote sensing datasets and morphometric analysis we analyse debris flows sourced above the town of isafjor ur iceland two debris flow triggering processes were previously hypothesized for this site i slope failure characterised by landslides evolving into debris flows and ii the fire hose effect in which debris accumulated in pre existing steep sided bedrock passages is transported by a surge of water it is unknown which process dominates and determines the local risk to investigate this question we compare airborne lidar elevation models and aerial photographs collected in 2007 with similar data from 2013 we find that two new debris flow tracks were created by slope failures these are characterised by steep sliding surfaces and lateral leveed channels slope failure also occurred in two large recently active tracks creating the preparatory conditions for the fire hose effect to mobilise existing debris these tracks show alternating zones of fill and scour along their length and debris stored below the source area at rest angles 35 our approach allows us to identify and quantify the morphological changes produced by slope failure release process which generated the preparatory conditions for the fire hose effect as debris flows are rarely observed in action and morphological changes induced by them are difficult to detect and monitor the same approach could be applied to other landscapes to understand debris flow initiation in absence of other monitoring information and can improve the identification of zones at risk in inhabited areas near hillslopes with potential for debris flows

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

morphometric analysis of debris flows and their source areas using gis important factors for the initiation of debris flows include available loose sediment torrential rainfall and topographic conditions the objective of this study is to identify topographic features of debris flows and conditions favorable for debris flow initiation based on geomorphological analyses of 11 river basins in northern and central taiwan morphometric indices were derived from 10 m grid digital terrain models before and after debris flow events using gis the indices include the stream power index spi topographic wetness index twi sediment transport capacity index elevation relief ratio form factor effective basin area and slope gradient the results show that debris flows tend to initiate from steep slopes or landslides with higher twi values debris flows are expected in basins with higher spi and twi basins with lower slope gradients and spi but higher twi may also have a high potential for debris flow spi changes most significantly due to a debris flow event particularly in steep basins

elastic geobarometry for anisotropic inclusions in cubic hosts abstract mineral inclusions entrapped in other minerals may record the local stresses at the moment of their entrapment in the deep earth when rocks are exhumed to the surface of the earth residual stresses and strains may still be preserved in the inclusion if measured and interpreted correctly through elastic geobarometry they give us invaluable information on the pressures p and temperatures t of metamorphism current estimates of p and t of entrapment rely on simplified models that assumes that the inclusion is spherical and embedded in an infinite host and that their elastic properties are isotropic we report a new method for elastic geobarometry for anisotropic inclusions in quasi isotropic hosts the change of strain in the inclusion is modelled with the axial equations of state of the host and the inclusion their elastic interaction is accounted for by introducing a 4th rank tensor the relaxation tensor that can be evaluated numerically for any symmetry of the host and the inclusion and for any geometry of the system this approach can be used to predict the residual strain stress state developed in an inclusion after exhumation from known entrapment conditions or to estimate the entrapment conditions from the residual strain measured in real inclusions in general anisotropic strain and stress states are developed in non cubic mineral inclusions such as quartz and zircon with deviatoric stresses typically limited to few kbars for garnet hosts the effect of the mutual crystallographic orientation between the host and the inclusion on the residual strain and stress is negligible when the inclusion is spherical and isolated assuming external hydrostatic conditions our results suggest that the isotropic and the new anisotropic models give estimations of entrapment conditions within 2

hydrological and geomorphological basin and catchment characteristics of lake nam co south central tibet abstract for lake nam co south central tibetan plateau geomorphological features and hydrological characteristics have been compiled to provide an overview of the landscape character information is based on primary data collected during field campaigns in the summers of 2005 and 2006 and secondary data as available from satellite images nam co is located at the intersection of the westerlies the winter monsoon the south west asian monsoon and the east asian monsoon it is situated in a graben structure landforms of the drainage basin are highly influenced by tectonics superimposed by fluvial and periglacial processes and locally by glacial and aeolian processes its drainage basin is endorheic thus lake level is primarily controlled by the balance between input through precipitation or inflow streams and evaporation as the output the significance of lake water evaporation is evidenced by the salinity and measurable increase of 2h and 18o of the lake water when compared to the inflow streams and precipitation maximum conductivities total 431 s mm 1 for the inflowing river waters and 1920 s mm 1 for the lake water overall the solute contents are low and characterise nam co as a pristine environment dominant ions are calcium and bicarbonate in river waters sulphate contents are relatively high in nam co and the lake is also characterised by high boron values a significant decrease in lake water salinity during the past two decades is likely related to increased freshwater input

simulation of event based landslides and debris flows at watershed level abstract a coupled model has been developed to simulate at watershed level landslides and debris flows induced by a severe typhoon tropical cyclone in taiwan the model comprises a landslide susceptibility model to predict landslide occurrence an empirical model to select debris flow initiation points and a debris flow model to simulate the transport and deposit of failed materials from the identified source areas in raster format with a 10 m spatial resolution the model output includes unstable cells debris flow initiation cells debris flow velocities runout paths and deposition zones the model was first tested and calibrated in a small area where the damage by landslides had been investigated and recorded it was then applied to a watershed and the simulation results were validated by comparing them with a landslide debris flow inventory map prepared from satellite images using a multiple change detection technique model test and validation results confirm the usefulness of the model in predicting the number and size of affected areas landslides and runouts combined runout path and volume of runout deposits it is a common practice in taiwan to separate landslide and debris flow inventories and to study debris flows only in select drainage basins this study suggests that landslide and debris flow should be modeled as a sequential process for efficient watershed management

an empirical approach to studying debris flows implications for planetary modeling studies 1 high resolution images acquired by the mars global survey mars orbiter camera show gullies on the walls of impact craters and valley systems on mars depositional aprons associated with these gullies have been interpreted by malin and edgett 2000 to be characteristic of debris flow and to indicate the presence of sources of liquid water at shallow depths below the martian surface by focusing on a terrestrial debris flow we test the application of chezy type modeling to provide more direct estimates of the dynamics of proposed debris flows on mars traditionally planetary scientists constrained by available remotely sensed data have used a range of flow models to gain insights from deposits into the behavior and rheologic nature of features such as lava flows debris flows and gravity driven flows on the basis of these model results broad interpretations of the physics governing flows of granular materials have been tempting based on limited field derived data this study tests and validates the extent to which the absolute value and relative variations of empirical parameters derived from the chezy type models describe the behavior of the general s slide debris flow 38 24 n 78 23 w in madison county virginia the results indicate that extreme caution must be taken when interpreting model results for turbulent flows of granular materials we obtained high precision topographic profiles superelevation data sedimentary facies and sedimentary textural properties over the debris flow this study focuses on the empirical parameter c whose value gauges energy dissipation in a flow thereby called flow resistance using field observations both variations and absolute values of c along the debris flow have been computed using two approaches 1 assuming constant volumetric flow rate q where only topography and high resolution images are required to compute channel dimensions and 2 a variable q calculated using field derived data assuming near newtonian flow conditions in the debris flow estimated values of c range from 0 035 to 0 099 when q is fixed c decreases as a function of distance downstream when q varies and c is computed from field derived flow speeds its value tends to increase downstream slightly these opposite results have been compared to the field observations to determine which best describes the behavior of the flow the variations in c downstream obtained using the flow speeds are most consistent with the geomorphic evidence for erosion of material by the debris flow and the presence of bends in the channel the average values of c 0 036 0 33 for the general s slide have been compared with computed c values for newtonian and near newtonian flows to assess the rheology of the flow during emplacement our terrestrial study demonstrates that advances in understanding of the dynamics of debris flows on the mars depends on obtaining debris flow speeds in addition to channel topography and flow thickness rather than just on channel topography flow thickness and the assumption that q is constant mars orbiter camera moc and mars observer laser altimeter mola data can be used to derive channel topography flow thickness and possibly flow speeds such data will provide more direct estimates of the dynamics of debris flows on mars than are currently available

a combined morphometric sedimentary gis and modelling analysis of flooding and debris flow hazard on a composite alluvial fan caveside tasmania abstract two episodes of intense flooding and sediment movement occurred in the westmorland stream alluvial system near caveside australia in january 2011 and june 2016 the events were investigated in order to better understand the drivers and functioning of this composite alluvial system on a larger scale so as to provide awareness of the potential hazard from future flood and debris flow events a novel combination of methods was employed including field surveys catchment morphometry gis mapping from lidar and aerial imagery and hydraulic modelling using riverflow 2d software both events were initiated by extreme rainfall events

estimating the mud depth of debris flow in a natural river channel a theoretical approach and its engineering application mud depth of debris flow is an essential parameter for assessing the hazard magnitude in an event however direct prediction of mud depth in a natural river channel is a scientific challenge because current methods often treat the complex relief of bed surface as a rectangular one which makes the prediction illogical in this paper we propose a new theoretical approach the so called numerical integral method based approach for estimating the maximum mud depth of debris flow at a complex cross section in a natural river channel given a predefined peak discharge of the debris flow event the numerical integral method based iteration algorithm uses the riemann method to search for an approximate mud depth in contrast to the previous methods the presented approach addresses an important issue namely it takes into account the complex shape of the bed surface and superelevation at the bend for natural channels two cases are used to illustrate the performance and advantages of the presented approach one is a well documented event in the previous study and the other is a debris flow event after ms 8 0 wenchuan earthquake an engineering application regarding the rational design of a debris flow canal is subsequently discussed the canal was completely destroyed in a debris flow event in 2008 we used the proposed method to back analyze the mud depth and velocity in the canal it was found that the abrupt decrease of mud depth from the natural channel to the concrete canal significantly reduced the transportation capability thereby causing blockage in the canal the canal was modified and reconstructed in 2009 with suggested improvements from the proposed method and successfully transported subsequent debris flow in 2011

diamond garnet geobarometry the role of garnet compressibility and expansivity abstract we report p v and t v equations of state eos for synthetic single crystal pyrope py mg3al2si3o12 and the p v eos for synthetic single crystals of almandine alm fe3al2si3o12 as well as an intermediate composition py60alm40 as measured by in situ high pressure and high temperature x ray diffraction experiments the unit cell volumes of the three samples were measured at room temperature and different pressures and up to about 8 gpa in a diamond anvil cell the high temperature experiment was carried out using a micro furnace the pressure volume data were fitted to a third order birch murnaghan eos giving the following coefficients v0 1506 15 16 a3 kt0 163 7 1 7 gpa and k 6 4 4 for pyrope v0 1533 52 10 a3 kt0 172 6 1 5 gpa and k 5 8 5 for almandine and v0 1516 32 13 a3 kt0 167 2 1 7 gpa and k 5 6 5 for the intermediate py60alm40 composition the unit cell volume along the pyrope almandine join changes linearly within the error of measurement indicating ideality in the volume of mixing behaviour for the solid solution the first pressure derivative k for all three garnets is similar within experimental uncertainty with an average value of k 6 0 4 the thermal expansion parameters for end member pyrope as described using to the kroll type eos with the einstein temperature e fixed to 320 k are 303 k 1 bar 2 543 5 10 5 k 1 and v0 1504 64 4 a3 the determined thermoelastic parameters were combined in a thermal pressure type eos thermal p type eos to calculate the entrapment pressures pe for natural garnet inclusions in diamonds at mantle temperatures a calculated pressure of 5 8 gpa at t 1500 k using our newly determined thermoelastic parameters appears to be more consistent with diamond forming conditions compared to the higher pressures that range up to 6 8 gpa at t 1500 k which are obtained using thermoelastic data in the literature

observation and simulation of lake air heat and water transfer processes in a high altitude shallow lake on the tibetan plateau lakes are an important part of the landscape on the tibetan plateau most of the plateau lakes area has been expanding in recent years but lake atmosphere energy and water interaction is poorly understood because of a lack of observational data and adequate modeling systems based on the eddy covariance observation over a high altitude shallow and small lake the small nam co lake during an ice free period from 10 april to 30 august 2012 this study analyzes the lake air heat and water vapor turbulent transfer processes and evaluates two popular lake air exchange models a bulk aerodynamic transfer model b model and a multilayer model m model our main results are as follows 1 observations show that the bulk transfer coefficient ce and roughness length zoq for water are higher than those for heat ch and z0h especially under low wind speed 2 both models underestimate turbulent fluxes due to inaccurate values of the charnock coefficient and the roughness reynolds number rr which are both important parameters for calculating the roughness length for momentum z0m over water 3 within a reasonable range of 0 013 0 035 for rough flow and rr for smooth flow rr 0 11 are 0 031 and 0 54 respectively by our observation the wave pattern of shorter wavelength gives a larger z0m in the small and shallow lake and 4 the b model and the m model gave consistent results and both models are more suitable for simulation of turbulent flux exchange after z0m optimization

evaluation of glacier changes in high mountain asia based on 10 year grace rl05 models in this paper 10 years of time variable gravity data from the gravity recovery and climate experiment release 05 have been used to evaluate the glacier melting rate in high mountain asia hma using a new computing scheme i e the space domain inverse method we find that in hma area there are three different kinds of signal sources that should be treated together the two generally accepted sources glacier melting and india underground water depletion are estimated to change at the rate of 35 0 5 8 gt yr 0 09 mm yr sea level rising and 30 6 5 0 gt yr respectively the third source is the remarkable positive signal 30 gt yr in the inner tibetan plateau which is challenging to explain further we have found that there is a 5 year undulation in pamir and karakoram which can explain the controversies of the previous studies on the glacier melting rate here this 5 year signal can be explained by the influence of arctic oscillation and el nino southern oscillation

gis assisted modelling for debris flow hazard assessment based on the events of may 1998 in the area of sarno southern italy part i maximum run out based on the debris flow events that occurred in may 1998 in the area of sarno southern italy this paper presents an approach to simulate debris flow maximum run out on the basis of the flow source areas and an average thickness of 1 2 m of the scarps we estimated debris flow volumes of the order of 104 and 105 m3 flow mobility ratios h l derived from the x y z coordinates of the lower most limit of the source areas i e apex of the alluvial fan and the distal limit of the flows ranged between 0 27 and 0 09 we performed regression analyses that showed a good correlation between the estimated flow volumes and mobility ratios this paper presents a methodology for predicting maximum run out of future debris flow events based on the developed empirical relationship we implemented the equation that resulted from the calibration as a set of gis macros written in visual basic for applications vba and running within arcgis we carried out sensitivity analyses and observed that hazard mapping with this methodology should attempt to delineate hazard zones with a minimum horizontal resolution of 0 4 km the developed procedure enables the rapid delineation of debris flow maximum extent within reasonable levels of uncertainty it incorporates sensitivities and it facilitates hazard assessments via graphic user interfaces and with modest computing resources copyright 2007 john wiley sons ltd

volcaniclastic debris flows in the clanio valley campania italy insights for the assessment of hazard potential abstract the rugged and steep slopes of the clanio valley campania southern italy mantled by volcaniclastic deposits from explosive eruptions of somma vesuvius and phlegraean fields volcanoes have a great potential for generating volcaniclastic debris flows during the well known meteorological event of may 5 6 1998 which triggered tens of debris flows causing enormous damage and casualties in the area of sarno quindici siano bracigliano sqsb the clanio valley was also affected by these hazardous phenomena debris flows were triggered by the failure of the volcaniclastic cover of the carbonate relief in the form of soil slips mainly on the sides of steep valleys slope between 26 and 45 a map of the hazard potential was created on the basis of both field and computer assisted morphometric data three classes characterised by a high medium and low hazard potential were distinguished within the higher class a better and more detailed zonation was obtained by studying the shape of the disrupted and undisrupted basins during the may 5 6 1998 event in the nearby sarno quindici siano bracigliano area this type of morphometric analysis can be applied rapidly by using a digital elevation model dem which allows a rapid investigation of large scale areas such an approach can be useful in areas characterised by similar geological and geomorphological settings

potential forcing mechanisms of holocene lake level changes at nam co tibetan plateau inferred from the stable isotopic composition of shells of the gastropod radix the timing of lake level fluctuations on the tibetan plateau and their relationship with climatic changes is still under debate and the main reason for this is the lack of suitable archives for reconstructing the paleohydrology and paleoclimatology of the lakes here we present the results of analyses of the shell geochemistry of radix sp from an exposed terrace of nam co lake on the south central tibetan plateau optically stimulated luminescence osl dating reveals that deep water lacustrine sediments formed between ca 4 4 and 2 2 ka suggesting a high and stable lake level significantly above the present the results of sr ca 13c and 18o analyses of the fossil shells of radix sp indicate that during the mid to late holocene lake level variations in nam co were mainly controlled by variations in the indian summer monsoon a trend of decreasing evaporation also played an important role comparison with other results suggests a consistent pattern of mid to late holocene lake level changes acro

from precipitation to runoff stable isotopic fractionation effect of glacier melting on a catchment scale stable isotope variability and fractionation associated with transformation of precipitation accumulation to firn to glacial river water is critical in a variety of climatic hydrological and paleoenvironmental studies this paper documents the modification of stable isotopes in water from precipitation to glacier runoff in an alpine catchment located in the central tibetan plateau isotopic changes are observed by sampling firnpack profiles glacier surface snow ice meltwater on the glacier surface and catchment river water at different times during a melt season results show the isotopic fractionation effects associated with glacier melt processes the slope of the d 18o regression line and the deuterium excess values decreased from the initial precipitation to the melt impacted firnpack slope from 9 3 to 8 5 and average d excess from 13 4 to 7 4 the slope of the d 18o line further decreased to 7 6 for the glacier runoff water the glacier surface snow ice from different locations which produces the main runoff had the same d 18o line slope but lower deuterium excess by 3 9 compared to values observed in the firnpack profile during the melt season the d 18o regression line for the river water exhibited a lower slope compared to the surface snow ice samples although they were closely located on the d 18o plot isotope values for the river and glacier surface meltwater showed little scatter around the d 18o regression line although the samples were from different glaciers and were collected on different days results indicate a high consistency of isotopic fractionation in the d 18o relationships as well as a general consistency and temporal covariation of meltwater isotope values at the catchment scale copyright 2013 john wiley sons ltd

evaporative fractions and elevation effects on stable isotopes of high elevation lakes and streams in arid western himalaya summary isotopes of oxygen and hydrogen in water from streams snow and lakes were used to model the ratio of evaporation to total inflow e i of four high elevation lakes in closed basins in the indian himalaya air temperature and relative humidity h data from meteorological stations and global climate grids gmao merra were used as input to the model a second model of the volume of inflow during snowmelt constrained the magnitude of seasonal variability in isotopic composition similar to other areas of the himalaya elevation was a strong determinant of isotopic composition of stream water suggesting that heavier isotopes rain out at lower elevations deuterium excess d in stream water suggests that summer precipitation originating from the bay of bengal rather than winter precipitation from central asia is the dominant source of precipitation for the largest and deepest lakes 15 m e i was 77 87 and 18 50 for two shallow lakes

hydrological variations on the central tibetan plateau since the last glacial maximum and their teleconnection to inter regional and hemispheric climate variations decadal to sub decadal variability of inflow evaporation and biological productivity derived from lake nam co was used to reconstruct hydrological changes for the past ca 24 k cal a bp the timing of these variations corresponds to known climatic shifts on the northern hemisphere after a dry and cold last glacial maximum the lake level of nam co initially rose at ca 20 k cal a bp moist but further cold conditions between ca 16 2 and 14 k cal a bp correspond to heinrich event 1 a warm and moist phase between ca 14 and 13 k cal a bp is expressed as a massive enhancement in inflow and biological productivity and might be associated with a first intensification of the indian ocean summer monsoon coinciding with the bolling allerod complex a two step decrease in inflow and a contemporaneous decline in biological productivity until ca 11 8 k cal a bp points to cool and dry conditions during the younger dryas lake levels peak at ca 9 4 k cal a bp although hydrological conditions remain relatively stable during the holocene with only low amplitude variations observed

assessment of the reliability of elastic geobarometry with quartz inclusions abstract elastic geobarometry makes use of the contrast in elastic proprieties between host and inclusion crystals to determine the entrapment conditions of the inclusions from the residual stress and strain measured in the inclusion when its host is at ambient conditions the theoretical basis has been developed extensively in the past few years but an experimental validation of the method is still required we performed two syntheses experiments with quartz inclusions in pure almandine garnet at eclogitic conditions experiment labelled alm 1 with synthesis performed at p 3 0 gpa and t 775 c and alm 2 at p 2 5 gpa and t 800 c all the experiments have been carried out in a piston cylinder press isolated fully enclosed quartz inclusions in the recovered garnets have been then measured using micro raman spectroscopy all fully buried inclusions exhibit raman peaks at higher frequencies and wavenumbers than those obtained from quartz crystals at ambient pressure if these peak shifts are interpreted as a remnant pressures by use of hydrostatic calibrations of the raman shifts of quartz with pressure the remnant pressures show a large spread in values and lead to significant errors in back calculated entrapment pressures of up to 1 4 gpa for inclusions synthesised at 3 0 gpa these results confirm that quartz inclusions trapped inside garnet are not subject to hydrostatic pressure we therefore used the phonon mode gruneisen tensors of quartz to calculate the full strain state of each inclusion from which the full anisotropic stress state can be calculated by using the elastic properties of quartz the mean residual remnant stress of the inclusions determined in this way show a much smaller spread in values entrapment pressures calculated from this mean stress with the isotropic model for host inclusion systems differ from the known experimental values by

gis assisted modelling for debris flow hazard assessment based on the events of may 1998 in the area of sarno southern italy ii velocity and dynamic pressure the velocity and dynamic pressure of debris flows are critical determinants of the impact of these natural phenomena on infrastructure therefore the prediction of these parameters is critical for hazard assessment and vulnerability analysis we present here an approach to predict the velocity of debris flows on the basis of the energy line concept first we obtained empirically and field based estimates of debris flow peak discharge mean velocity at peak discharge and velocity at channel bends and within the fans of ten of the debris flow events that occurred in may 1998 in the area of sarno southern italy we used this data to calibrate regression models that enable the prediction of velocity as a function of the vertical distance between the energy line and the surface despite the complexity in morphology and behaviour of these flows the statistical fits were good and the debris flow velocities can be predicted with an associated uncertainty of less than 30 and less than 3 m s 1 we wrote code in visual basic for applications vba that runs within arcgis to implement the results of these calibrations and enable the automatic production of velocity and dynamic pressure maps the collected data and resulting empirical models constitute a realistic basis for more complex numerical modelling in addition the gis implementation constitutes a useful decision support tool for real time hazard mitigation copyright 2008 john wiley sons ltd

calculation of river discharge and prediction of lake height from satellite radar altimetry example for the lake chad basin 1 the application of satellite radar altimetry to the determination of lake and river elevations has been used in numerous projects and is well validated here we show that with the aid of ground based information this technique can be extended to determine river discharge and predict downstream lake and marsh height the lake chad basin provides an ideal case study due to its well known hydrology and complex lake and marsh morphology and because prediction of lake and marsh height has been identified as potentially useful to people living in the region altimetric stage measurements from the topex poseidon satellite at the chari ouham confluence estimate river discharge about 500 km downstream at n djamena 10 days in advance r2 0 9562 via simple linear correlation methods the stage measurements successfully estimate the height of the permanent waters of the lake 600 km downstream 39 days in advance r2 0 9297 predicting the water height on the western marshes of the lake bed is poorer r2 0 7958 due to a change in response time of the local stage to the seasonal floods coincident with an observed increase in mean water level in the latter half of the 1990s before 1997 a 96 day phase lag results in the best fit r2 0 6463 after 1997 the best fit is obtained with a 66 day phase lag r2 0 8139 the excellent river discharge and lake height predictions show that altimetry is a useful tool where ground based data are difficult to obtain and where rapid water resource assessment is desirable

quantitative analysis of debris torrent hazards for design of remedial measures debris torrents which are rapid flows of soil and organic debris down steep mountain channels are a major natural hazard in many parts of british columbia a series of recent occurrences along the

numerical simulation of some lahars from mount st helens abstract an unsteady open channel model is used to simulate lahars discharge flow depth peak arrival time etc under the restriction of negligible volume and solid fraction variations and of channelled flow the model is able to deal with the propagation of steep fronts and transitions from a supercritical to a subcritical flow regime and vice versa conditions frequently occurring on account of the rapidity of lahar triggering mechanisms large water debris volumes are often mobilized in a very short time and of topographical characteristics the model is based on equations governing balance of mass and momentum while the energy dissipation term is expressed as a power function of the flow depth and discharge two past lahars at mount st helens the pine creek and muddy river lahars of may 18 1980 are simulated and the results obtained are discussed for these lahars the triggering mechanism was the melting of snow and ice due to pyroclastic flows and surges many millions of cubic meters of water mostly from the melting of ice and snow and sediments eroded material and pyroclastic products were mobilized in only a few minutes the simulation begins at some kilometers from the vent where lahar volumes reach an almost constant value and the flow is channelled the triggering mechanism plays a fundamental role in the downvalley destructive power of a lahar initial hydrographs characterized by steep slopes such as those occurring as a consequence of pyroclastic flows and surges rapidly flatten downvalley as predicted by the model conversely hydrographs with a prolonged peak discharge even if the peak value is smaller undergo little changes over distances of lens of kilometers with disastrous consequences as in the case of the 1980 north fork lahar at mount st helens triggered by the seismic shaking of an avalanche debris

field and laboratory investigations of runout distances of debris flows in the dolomites eastern italian alps abstract the estimation of runout distances on fans has a major role in assessing debris flow hazards different methods have been devised for this purpose volume balance limiting topographic methods empirical equations and physical approaches data collected from field observations are the basis for developing testing and improving predictive methods while laboratory tests on small scale models are another suitable approach for studying debris flow runout under controlled conditions and for developing predictive equations this paper analyses the problem of assessing runout distance focusing on six debris flows that were triggered on july 5th 2006 by intense rainfall near cortina d ampezzo dolomites north eastern italy detailed field surveys were carried out immediately after the event in the triggering zone along the channels and in the deposition areas a fine scale digital terrain model of the study area was established by aerial lidar measurements total travel and runout distances on fans measured in the field were compared with the results of formulae from the literature empirical statistical and physically oriented and samples of sediment collected from deposition lobes were used for laboratory tests the experimental device employed in the tests consists of a tilting flume with an inclination from 0 to 38 on which a steel tank with a removable gate was installed at variable distances from the outlet a final horizontal plane works as the deposition area samples of different volumes and variable sediment concentrations were tested multiple regression analysis was used to assess the length of the deposits as a function of both the potential energy of the mass and the sediment concentration of the flow our comparison of the results of laboratory tests with field data suggests that an energy based runout formula might predict the runout distances of debris flows in the dolomites

late cretaceous plateau deserts in the south china block and quaternary analogues sedimentology dune reconstruction and wind water interactions abstract plateau deserts are among those continental systems with the most significant examples of clastic deposits associated with the complex combination of the action of ice wind and water the late cretaceous rocks of china contain the record of desert systems migration and partial destruction in a palaeoplateau desert the evolution of the south china block during late cretaceous was characterized by widespread destructive plate margin activity this favoured orogenic uplift and high altitude mountain ranges of which a direct consequence was a widespread rain shadow effect triggering desertification and erg expansion similar to that of quaternary counterparts in the tibetan plateau this work presents a detailed analysis of the sedimentology stratigraphic architecture palaeogeography and palaeocurrent reconstruction of aeolian and associated alluvial depositional systems the reconstruction of aeolian bedforms based on field data analysis indicates that during late cretaceous draas and crescentic dunes accumulated and migrated in extensive intermontane desert systems heavy rains led to partial destruction of aeolian dunes and the reworking of aeolian sands in interdraa corridors the fault controlled subsidence and an increasing input of windblown sediments favoured the long lasting accumulation of the erg system possible monsoonal rains recharged the groundwater system causing the rise of the regional phreatic level that favoured the ulterior long lasting preservation of the aeolian system in the xinjiang basin the dimensions and processes inferred from this cretaceous desert system are similar to those observed today in the linking zone of the taklamakan gobi deserts where meltwater flows from alpine glaciers in surrounding mountain ranges recharge the alluvial and fluvial network of the erg margin the occurrence of striated cobbles in the alluvial facies suggests glacial activity in the catchment areas of the cretaceous plateau

variations in water level and glacier mass balance in nam co lake nyainqentanglha range tibetan plateau based on icesat data for 2003 09 water level fluctuations of inland lakes are related to regional scale climate changes and reflect variations in evaporation precipitation and glacier meltwater flowing into the lake area in its catchment in this paper ice cloud and land elevation satellite icesat altimeter data and landsat imagery 2002 09 are used to estimate nam co lake nyainqentanglha range tibetan plateau water elevation changes during 2002 09 in 2003 nam co lake covered an area of 1998 8 4 2 km 2 and was situated at 4723 m a s l over such inland water bodies icesat altimeter data offer both wide coverage and spatial and temporal accuracy we combine remote sensing and gis technology to map and reconstruct lake area and increased volume changes during a 7 year time series nam co lake water level increased by 2 4 0 12 m 0 33 m a 1 between 23 february 2003 and 1 october 2009 and lake volume increased by 4 9 0 5 km 3 in the past 7 years nam co lake area has increased from 1998 78 5 4 to 2023 8 3 4 km 2 the glacier covered area has decreased from 832 34 to 821 0 km 2 and the drainage basin area has decreased from 201 1 4 2 to 196 1 2 3 km 2 however the most spectacular feature is the continual water level rise from 2003 to 2009 without an obvious associated increase in precipitation based on digital elevation models dems from shuttle radar topography mission srtm dem data and corrected icesat elevation data significant changes to glacier mass balance in the western nyainqentanglha mountains are indicated nyainqentanglha mountain glacier surface elevations decreased by 8 39 0 45 m during 2003 09 over the same period at least 1 01 km 3 of glacial meltwater flowed into nam co lake assuming a glacial runoff coefficient of 0 6 the mean glacier mass balance value is 490 mm w e over the corresponding period indicating that glacier meltwater in the catchment contributes to lake level rise the contribution rate of glacial meltwater to lake water volume rise is 20 75 the temporal lake level fluctuation correlates with temperature variations over the same time span

new lakes in the taklamakan desert 1 at the beginning of this century some new lakes unexpectedly appeared in the taklamakan desert one of the largest and driest deserts in the world the origin of the water in the new lakes however has been a matter of debate we test the hypotheses by analyzing water samples collected from the new lakes the bosten lake and the foothills of the mountains that surround the desert using the isotopic composition of these waters as tracers together with data from remote sensing local weather stations and stream gauges we infer that the new lakes may originate from increased recharge of groundwater from meltwater in the nearby mountains we further speculate supported by first order simulation of earthquake induced discharge of groundwater from mountains that the source of this increased recharge may be related to earthquake induced discharge of groundwater from nearby altyn and kunlun mountains

quartz in garnet inclusion barometry under fire reducing uncertainty from model estimates quartz inclusions in garnet are suitable for barometry because quartz is highly compressible relative to garnet and the garnet host can maintain large stress differences generated as pressure temperature conditions change however experimental validation of the quartz in garnet approach has been limited raising questions concerning the accuracy of calculated entrapment pressure here we test the results of quartz in garnet barometry by conducting in situ raman analysis of natural inclusions over a range of temperatures 175 to 600 c we assess the temperature t dependence of inclusion pressure p incl at 1 bar and compare calculated entrapment pressures derived from measurements at different temperatures experiments used two quartz standards oriented c and and fully encapsulated quartz inclusions from three different terranes retaining different p incl at room t 444 296 and 755 mpa the stretched quartz inclusion p incl 0 had the greatest increase in p incl 264 mpa during heating from 25 to 500 c whereas the high p inclusions underwent less change 138 mpa in p incl over the same t interval the greater t sensitivity of inclusions with low p incl reflects the greater thermal expansivity of quartz near the to quartz transition while measured p incl t trends are consistent with predictions numerical models tend to overestimate p incl at elevated t and calculated entrapment pressures show an unrealistic dependence on reference t raman spectroscopic measurements conducted in situ at elevated t provide optimal results in addition we have recalibrated the thermal portion of the numerical method based on the present results and provide new empirical expressions for improved quartz in garnet barometry

isotopic signatures of precipitation surface water and groundwater interactions poyang lake basin china poyang lake whose hydrological characteristics are impacted by the operation of the three gorges dam is the largest freshwater lake in china however water cycle mechanisms in the poyang lake basin remain poorly understood in this study stable isotopes d and 18o of water samples taken in april july and november 2013 and hydrological data are used to investigate the interactions between precipitation river water lake water and shallow groundwater in the poyang lake region the isotopic results show seasonal variations in precipitation surface water and groundwater which provides a set of tools to identify waters that have different histories the similar isotopic compositions of river water and groundwater suggest a close hydrological connection hydrological data present a positive correlation between river run off and precipitation however isotopic results show that rivers in the poyang lake basin in different seasons are primarily recharged by subsurface run off with different proportion between base flow and near surface quick flow rather than by surface run off directly formed by concurrent rainfall due to the geological characteristics of stratum in the poyang lake basin it is easier for precipitation to infiltrate into soil and recharge groundwater than to form direct surface flow that feeds rivers the groundwater system is like a huge reservoir which can effectively impound rainfall water playing an important role in restraining floodwater during the flood season and in ensuring river run off supply during the dry season

cosmogenic 35s measurements in the tibetan plateau to quantify glacier snowmelt the cosmogenic radionuclide s t 87 days is a unique tracer for high altitude air mass and has been used extensively to understand stratospheric air mass mixing in this paper we investigate if s can be utilized as an independent tracer to quantify glacier melt we report the first measurements of s in samples collected from the tibetan plateau during 2009 2012 with an aim to interpret s in atmospheric particles and their deposition over glacier and snowmelts our measurements show that s activity in the aerosol phase varies from 116 13 to 2229 52 atoms m resulting in higher values during winter spring and lower values during summer autumn this seasonality is likely due to higher mixing of s rich stratospheric air masses during winter spring and s poor air masses from the bay of bengal during the asian summer monsoon the average s activity in the zhadang glacier was found to be 3 8 times higher relative to the nearby lake water the main source of s activity in the zhadang glacier is atmospheric deposition whereas both atmospheric deposition and glacier snowmelt are the primary sources in the nam co lake the focus of this study is to quantitatively determine the spatial and temporal variations in glacier snowmelt in the future extensive sampling of aerosols and snow is required for determining s in combination with stable oxygen isotopes in sulfate to better understand the glacier melt process and hydrological cycle on the tibetan plateau

a fluid dynamics approach to modelling the 18th march 2007 lahar at mt ruapehu new zealand lahars are water sediment mass flows from a volcanic source they can be triggered by a variety of mechanisms and span a continuum of flow rheology and hydraulic properties even within the same event lahars are extremely powerful landscaping agents and represent a considerable hazard potential however this highly dynamic character and a lack of direct measurements has made modelling lahars difficult this study therefore applies a fluid dynamics model delft3d to analyse the 18th march 2007 dam break lahar at mount ruapehu new zealand the modelled lahar routed through the whangaehu gorge in 30 min crossed the whangaehu fan in 60 min and then over a further 3 h travelled an additional 22 km distance along the whangaehu river to the tangiwai bridge the modelled mean frontal velocity was 6 5 m s 1 along the gorge although peak velocity reached up to 19 6 m s 1 the modelled lahar flow front progressively slowed across the fan but along the river it accelerated from 2 1 3 3 m s 1 calculated peak velocity along the river was 4 5 m s 1 these results generally compare well with gauged records with historical records and with other modelling approaches however discrepancies in frontal velocity and time to peak stage arise due to 1 specifying roughness which arises from slope variations between adjacent computational nodes and which is stage dependant and 2 due to rapid topographic changes that produce frequent hydraulic jumps which are inadequately accommodated in the numerical scheme the overall pattern of discharge attenuation and of relationships between topographic and hydraulic variables is similar to that calculated for lahars on other volcanoes this modelling method could be applied at other similar sites where a likely source hydrograph and high resolution topographic data are available these results have important implications for hazard management at ruapehu and for examining geomorphic and sedimentary impacts of this lahar

quantifying evaporation and its decadal change for lake nam co central tibetan plateau most lakes in the interior tibetan plateau have expanded rapidly since the late 1990s because of a lack of observations lake water balances and their changes are far from well understood evaporation is a component of the lake water balance and this study quantifies its magnitude decadal change and its contribution to the water balance changes in lake nam co one of the largest lakes on the tibetan plateau with an area of approximately 2000 km2 and a mean depth of approximately 40 m the lake temperature and the evaporation are simulated by the flake model the simulation results are validated against observed lake temperature profile from 2013 and moderate resolution imaging spectroradiometer lake surface temperature data from 2000 to 2014 the simulated latent heat flux and sensible heat flux are validated against bowen ratio derived estimates for 2013 based on the validated simulation results the long term mean annual evaporation is approximately 832 69 mm and this value is much less than the potential evaporation estimated using the penman monteith equation the annual evaporation from 1980 to 2014 displays a complex decadal oscillation mainly due to the changes in energy related terms air temperature and radiation the mean lake evaporation since the late 1990s is greater than previous periods thus this change in evaporation has suppressed the recent expansion of nam co