submarine debris flow impact on pipelines part i experimental investigation estimating the impact forces exerted by a submarine debris flow on a pipeline is a challenge and there is room for considerably more work to advance the state of the art to this end an experimental program was performed to investigate the impact on two pipeline installation scenarios 1 suspended pipeline and 2 laid on seafloor pipeline the results and observations from the experimental investigation are discussed the definition of reynolds number was modified for non newtonian fluids and an ad hoc method was developed to estimate the drag force exerted by an impact perpendicular to the pipe axis the method may be used in prototype situations to estimate the drag force from submarine debris flow impact on pipelines the experimental program was complemented by computational fluid dynamics cfd analyses the details of which are discussed in the accompanying paper

sedimentary record of recent tsunamis in the huelva estuary southwestern spain abstract the coast of the gulf of cadiz has been repeatedly struck by tsunamis during the late holocene and the historic period historical documents record at least seven catastrophic tsunamis affecting this coast while others have been detected by oceanic instruments nevertheless very few studies have documented the sedimentary record of these tsunamis in the low energy coastal environments of the gulf of cadiz the huelva estuary is located at the central sector of the gulf of cadiz and is a mesotidal estuary fed by the tinto and odiel rivers the mean tidal range of the huelva estuary is ca 2 m and the mean significant wave height is ca 0 5 m the outer part of the estuary is characterized by extensive sand rich sedimentary bodies of marine origin whereas the central and inner parts are infilled by muddy tidally deposited sediment bodies recorded within these estuarine sediment bodies are five laterally continuous shelly units these units display many of the typical characteristics of tsunami deposits each typically comprises an erosional base followed by a fining upwards sequence that begins with the shell accumulation and ends with bioturbated muddy sand the results of 14 c ages and recent radionuclides accumulation rates in this study illustrate that these five tsunami deposits correspond with known events that occurred in ad 1755 1531 949 1033 881 and 395 381 all of which are documented in historical sources

understanding how volume affects the mobility of dry debris flows 1 the prediction of the runout length l of large dry debris flows has long been the subject of a considerable research effort primarily due to the obvious concern caused by their destructive power one seemingly well established feature is the increase of the mobility of a rock avalanche defined as the ratio of the runout distance to the fall height with its volume v the physical nature of this lubrication mechanism remains however controversial in this paper we analyse field data and discrete numerical simulations of granular flows and demonstrate the geometrical origin of the apparent enhancement of the mobility with the volume we evidence the intertwined role of volume and topography and show the existence of two contributions in the runout defining two flow regimes one dominated by sliding in which the runout is independent of v and another dominated by spreading in which the runout is strongly dependent on v in the light of these results the search of a volume dependent lubrication mechanism appears to be an ill posed problem

on the mobility of pyroclastic currents in light of deposit thickness and clast size trends abstract pyroclastic currents pcs represent the most hazardous manifestations of explosive volcanic activity the evaluation of their mobility as related to the eruptive source parameters and the interactions with the surroundings along their path is crucial for hazard assessment at active volcanoes in order to define the areas exposed to their impacts here we report on two case studies from the latera volcanic complex vulsini volcanic district central italy that may approach the two end members of the classical spectrum of pc dynamics in terms of particle concentration and dominant flow regime i e dilute turbulent vs concentrated laminar pcs for the two examples we document specific and contrasting variation trends of deposit thickness and maximum lithic and pumice clast sizes with distance from vent which provide a further characterization in terms of forced vs inertial flow behavior in the first case thickness and maximum lithic and pumice sizes show a mild linear decrease with distance implying a sort of balance between forced and inertial regimes flow pressure and mass progressively drop via deposition along with flow competence for given source conditions i e mass eruption rate fountaining height erupting mixture etc and slope angle of topography the pc runout depends primarily on the waning density contrast between the flow and the surrounding atmosphere density current ending with the loft of the current the second case representative of moderate to large volume dense pcs derived by continuous feeding with high mass discharge rate i e from collapsing plinian columns or caldera forming events shows an increase of deposit thickness with distance which is accompanied by opposite lithic and pumice clast size distance trends i e decreasing lithic sizes and increasing pumice sizes downcurrent compatible with high particle concentration and forced non turbulent granular flow regime by analogy with the mobility of dry debris flows we suggest that the sliding component of transport which prevails in proximal to intermediate settings may account for the prevailing tendency of the pc to transport than to deposit which leaves behind relatively thin sheets with coarse lithics while the dominant spreading component downcurrent would result in increasing accumulation and the stacking of coarse pumice rich flow lobes in more distal settings the spreading component of transport would become more and more important with increasing material supply at pc source resulting in additional runout these findings cast new light on the first order controlling factors of flow mobility for the two pc end members laying the groundwork for determining the most relevant pc hazard parameters i e the maximum runout and the flow properties upon impact dynamic pressure burial potential temperature

critical slip surface and landslide volume of a soil slope under random earthquake ground motions finding the critical slip surface and estimating the landslide volume are of primary importance for slope seismic design however this may be difficult due to the uncertainty of ground motions to address this problem a new method for calculating uncertainties is recommended in this paper especially for the critical slip surface and landslide volume under random earthquake ground motions firstly a series of intensity frequency nonstationary random earthquake ground motions were generated based on an improved orthogonal expansion method a given number of potential slip surfaces were set in a soil slope subsequently the factor of safety fos of each slip surface for all ground motions was calculated and the minimum fos curves were obtained it was found that the critical slip surfaces and failure times are uncertain under different earthquakes the monte carlo method was used to verify the accuracy of probability density evolution method pdem and the results of the pdem and the monte carlo method are consistent meaning that the pedm has higher computational efficiency moreover the distributions of earthquake triggered landslide volume and landslide depth were analyzed by considering equivalent extreme events both landslide volume and depth exhibit a normal distribution for a homogeneous soil slope the framework of this study is meaningful for slope seismic design in engineering for example the location of critical slip surface can be used for slope reinforcement and the distribution of sliding volume can be used for disaster assessment

vector empirical orthogonal function modes of the ocean surface wind variability derived from satellite scatterometer data ocean surface winds derived from nscat quikscat and ers 1 2 scatterometer observations during a period from january 1992 to april 2000 were analyzed using the vector empirical orthogonal function veof method with the boreal winter and summer oscillation the first veof is dominated by the indian and east asian monsoons and also shows an annual cycle of the trade winds the second veof represents the boreal autumn and spring oscillation and reveals a transition state between winter and summer the third veof indicates the wind variability associated with el nino southern oscillation enso events because the temporal mode has a high correlation coefficient of 0 8 with the southern oscillation index soi furthermore the third mode reveals the teleconnection of the indian monsoon and wind variability over high latitude oceans such as the aleutian low system with enso events

massive ice avalanches on iapetus mobilized by friction reduction during flash heating the great distance travelled by long runout landslides observed previously on the earth and mars requires a mechanism of friction reduction identification and analysis of long runout landslides on saturn s moon iapetus suggests that the iapetian landslides are enabled by flash heating of the icy sliding surface

a perturbation solution for bingham plastic mudflows an analytical solution is proposed for laminar mudflows and debris flows that can be modeled by a bingham plastic law two dimensional unsteady nonuniform bingham flows released from a point source or a source of finite size dam break problem or mudslide problem on a steep slope are considered the method of matched asymptotic expansions was implemented to get a first order solution for the dam break problem the proposed model is found to be valid when the shock wave has advanced three reservoir lengths downstream also it is found that the bingham flow only propagates a finite distance downstream with the shock depth asymptotically approaching the yield depth and the shock velocity asymptotically falling to zero the hydrograph produced by a bingham flow is seen to have a slower and lower flood peak and a longer and higher flow tail than that produced by newtonian flow having the same dynamic viscosity comparison of the model predictions with laboratory observations shows reasonable agreement

sedimentological and geomorphological imprints of holocene tsunamis in southwestern spain an approach to establish the recurrence period this paper reviews the sedimentological and geomorphological imprints of prehistoric and historical tsunamis in the four main estuaries of sw spain these imprints include beach erosion filling of intertidal channels deposition of bioclastic layers washover fans and reworked aeolian sheets and the breaching of spits and tombolos most of these imprints were caused by the 218 209 bc and ad 1755 tsunamis although evidence of other tsunamis has been identified in these two events effects on human populations were severe and diverse such as human loss of life changes in coastal settlements and international borders damage to port infrastructure or flooding of marsh and inhabited areas new radiocarbon reservoir data were included in order to obtain an approach to the recurrence period of these high energy events 700 1000 years in this area 2013 elsevier b v

on the evolution of the qe ii storm i synoptic aspects abstract the hurricane force winds and heavy seas which battered the liner queen elizabeth ii on 10 and 11 september 1978 were associated with an extreme example of a meteorological bomb as defined by sanders and gyakum despite the existence of surface buoys and the relatively high density of mobile ships in the north atlantic real time weather analyses subjective forecasts and numerical prognoses all erred in the intensity and track of this storm in this study deficiencies in the real time surface analysis were compensated for by the addition of seasat a surface wind fields and previously discarded conventional ship reports this paper examines the synoptic aspects of this case with emphasis on physical mechanisms most likely responsible for the development the cyclone originated as a shallow barocline disturbance west of atlantic city new jersey and explosive deepening 60 mb 24 h commenced once the storm moved offshore and in association with cumulus convection adjacent to the storm cent

modeling the geostrophic drag coefficient for aidjex a model of the planetary boundary layer flow over the arctic pack ice was found to relate geostrophic flow determined from a large scale pressure field to the surface stress vector a summary of the model and some data comparison is presented

the landslide stage of the hsiaolin catastrophe simulation and validation 1 typhoon morakot struck southern taiwan in the summer of 2009 causing the most severe flooding since the 1950s in the early morning of august 9 rainfall triggered the hsiaolin landslide and the resulting debris avalanche covered the township of hsiaolin village kaohsiung around five hundred people were buried alive reconstruction of the runout of the debris avalanche would increase understanding of the large scale avalanches for future hazard mitigation purposes simulation of the debris avalanche runout can provide valuable information for this purpose a new continuum shallow water model is applied to flow over general topography the coulomb friction law is adopted the friction coefficient is initially determined by high pressure rotary shearing tests and subsequently fine tuned by an iterative procedure to minimize the difference between the simulation and the measurement the friction coefficients measured by laboratory tests are found to be in reasonable agreement with the best fit result of the simulation in addition voellmy rheology is applied but it is found that the role of the fluid viscous drag is insignificant the simulation result in the village area is further corroborated by near surface magnetic surveys these indicate that the northern part of the village is dislocated while the artifact structures of the southern part are buried near their original locations by comparing the landslide front and the flow direction of the simulation we are able to confirm as also described by survivors that the landslide swept the northern part of the village into the cishan river while the southern part was flooded subsequently by the debris from a dam breach about 20 min after the landslide

the reduction of friction in long runout landslides as an emergent phenomenon campbell et al 1995 modeled long runout landslides as granular flow using a soft particle code their model essentially simulates landslides from first principles and although no fluid or obvious mechanism for reduction of friction is included the model successfully reproduced many field observations of landslides e g the preservation of source stratigraphy in the final slide mass and a decreasing effective friction with increasing slide volume we extend the work of campbell et al 1995 with a focus on the mechanism that reduces friction in these slides we find sliding preferentially occurs when the overburden is relieved by pressure variations in the slide further analysis shows that our results are very similar to the predictions of the acoustic fluidization hypothesis moreover we determine that for long runout landslides the wavelength of vibrations associated with acoustic fluidization is determined by the size of the rock fragments in the slide

sea level changes an integrated approach sea level changes an integrated approach in october 1985 sepm sponsored a four day conference entitled sea level changes an integrated approach the purpose of the conference was to provide a forum for an interdisciplinary exchange of ideas on sea level changes and to provide an opportunity for integrating various types of evidence in approaching unresolved issues the conference was successful in bringing together scientists from industry academia and government representing all of the major geosciences disciplines presentations of many new papers plus significant releases of data that were previously held proprietary provided fertile ground for discussion this much cited volume represents the best of the material presented at the conference includes the early vail chart

seasat scatterometer detection of gale force winds near tropical cyclones hurricane center advisories specifying the radius of gale force winds gfw in tropical cyclones are severely limited by inadequate data their accuracy is especially vulnerable in the data void tropical ocean regions the seasat a satellite scatterometer sass sensed surface winds associated with numerous tropical cyclones although instrument design ruled out retrieval of winds within the inner core of the storm surface truth studies indicate sass can detect the threshold of gale force winds 17 18 1 with an accuracy comparable to the original seasat specifications 2 ms 1 or 10 and 20 accurate and abundant sass observations were thus used as verification for advisories specifying the radius of gale force winds for tropical cyclones in the pacific and atlantic ocean basins advisories were found to consistently overestimate the radius of gfw often by a factor of two in the central pacific large asymmetries in the gfw distribution measured by sass were often in considerable disagreement with symmetric circular and semicircular advisory values however advisories that had access to low level aircraft data closely matched sass measured gfw values

new insights on the runout of large landslides in the valles marineris canyons mars 1 analogy with lab scale dry granular flow experiments demonstrates that runouts and deposits heights of valles marineris vm landslides can be scaled on a curve varying primarily with the initial aspect ratio of the mobilized rock mass before slope failure this results suggests both that any interstitial fluid played a negligible part in the vm landslides dynamics and that mobility is not an appropriate tool to characterize their dynamics

self lubrication for long runout landslides examination by computer simulation this paper describes the use of a discrete particle computer simulation to test whether the apparent low friction exhibited by long runout landslides could be explained in terms of simple granular mechanics the flow structure consists of an active basal shear zone supporting the majority of the landslide which travels as a relatively solid plug the observed runout appears to depend on the total energy dissipation which is a trade off between 1 the inelasticity of the particles which governs the energy dissipated in each event and 2 the size of the dissipating shear zone which governs the number of particles that are actively dissipating energy very inelastic particles quickly dissipate the work performed at boundaries and result in thin dissipative zones as a result these two factors balance and the runout is nearly independent of particle inelasticity along the same lines increasing the boundary roughness was found to increase the size of the dissipative shear zone and markedly decrease the runout also a distribution of particle sizes destroyed ordered structures within the body which once again increases the dissipation and decreases the runout unfortunately the simulations also indicate that the runout should be independent of the depth of the flow and thus cannot account for the observed volumetric effect on runout

mesotidal estuarine sequences a perspective from the georgia bight abstract although much has been written about estuaries and estuarine sediments very few facies models have been proposed to date and considerable ambiguity remains in coastal classification schemes current stratigraphic concepts fail to elucidate not only the differences between certain deltaic estuarine and lagoon fill sequences but also the pronounced similarities between many riverine and salt marsh estuarine sequences these distinctive latero vertical successions recent and ancient warrant increased scrutiny and conceptual refinement preliminary stratigraphic models and definitions presented here based largely upon modern georgia estuaries should provide a broad framework for further evaluation and clarification of the above facies relationships from that standpoint an estuarine sequence consists of complex intertidal to subtidal mostly channel form facies dominated to some extent by tidal effects typically displaying abrupt variations in sediment texture and composition and in physical and biogenic sedimentary structures subtle to pronounced salinity gradients may be discernible nevertheless the features most diagnostic of the overall sequence are 1 tidally influenced channel form deposits and 2 characteristic bioturbate textures and trace fossils

submarine debris flow impact on pipelines part ii numerical analysis computational fluid dynamics cfd numerical analysis was employed to analyze the situations tested experimentally as described in part i the methodology and results of the cfd analyses are discussed and compared with the observations made from the experiments the numerical model performed satisfactorily with regard to obtaining the impact forces exerted on the model pipe as well as simulating the hydroplaning phenomenon and estimating slurry flow heights the experimental results were combined with the results of the cfd analyses to develop a practical method to compute the drag force caused by a submarine debris flow impact on a pipeline the cfd analyses provided some insight to the separated region characterization but the attempt to analyze the vortex shedding phenomenon as observed in the experiments was unsuccessful additional studies are required for better understanding of both the separated region characteristics and vortex shedding

predictability of long runout landslide motion implications from granular flow mechanics quality of landslide motion prediction is directly linked to the understanding of the basic flow mechanisms although it is known that landslides are granular mass flows and granular flow mechanics is an established area of research hypotheses on landslide motion are still based on simple geometrical relations and heuristic assumptions new insights into the development of flow properties of high speed high concentration granular flows are given by results of discrete particle simulations rapid granular flows are self organizing dynamic systems that are forced to develop a plastic body rheology this behaviour must be described by a coefficient of internal friction cm that refers to the center of mass of a flow coefficients of rapid granular flows of inelastic and rough particles which are typical for common rock materials do not vary significantly around cm 0 45 that is definitively smaller than the friction coefficient of soil creep 0 6 the motion of the center of mass is superimposed by the spreading of the granular mass that is controlled by the same plastic body rheology this combined motion is a scale invariant self similar process that depends only on the drop height of a landslide and its volume this allows specification of implications that must be given special attention in the development of future models for landslide prediction

field and laboratory analysis of the runout characteristics of hillslope debris flows in switzerland abstract hillslope debris flows are unconfined flows that originate by shallow failures in unconsolidated material at steep slopes in spite of their significant hazard for persons and infrastructure in mountainous regions research on hillslope debris flows is rather scarce in comparison to other landslide types this study focusses on the runout characteristics of hillslope debris flows applying two different approaches first detailed landslide inventories which include field measurements of 548 slope failures that occurred during the last two decades in seven parts of switzerland were analysed second laboratory tests were carried out to study the effect of the soil water content grain size distribution and mobilized volume on the runout behaviour of hillslope debris flows most of the failures in the field started as shallow translational slides at terrain slopes between 25 and 45 and involved volumes of some tens to a few hundred cubic meters an analysis of the runout distance of 117 hillslope debris flows showed that they normally travelled some tens of meters but sometimes the runout exceeded 300 m a positive relation between volume and runout distance and between volume and affected area was observed although there is considerable scatter in the data the affected area of 63 hillslope debris flows ranged from 100 to 1500 m2 based on the field data a 7 5 m long laboratory hillslope was designed with a geometrical scale factor of 20 a total of 75 runs with volumes from 4 to 20 dm3 water contents from 18 to 38 and four grain size distributions were carried out the laboratory tests revealed that water content is the dominant control but also the clay content strongly influences the runout distance and the affected area even a small increase in water or clay content produces a considerably larger or smaller runout distance respectively in contrast the influence of the volume on the runout was smaller and a positive relation was observed between these two parameters the field and laboratory results are in general agreement and consistent with the results of other studies the results of this work improve the understanding of hillslope debris flows and may aid in the hazard assessments of these processes

late quaternary infilling of the assu river embayment and related sea level changes in ne brazil abstract a detailed geomorphological survey using light detection and ranging lidar was carried out along the western part of the assu river valley ne brazil the study was complemented by the investigation of sedimentological mineralogical and sediment benthic foraminifera indicators within the 14c geochronological framework the integration of data sets permitted the reconstruction of the main phases in the evolution of this area during the holocene the shallow embayment which is now completely infilled acquired its present form within the limits of antecedent morphology developed since the last interglacial period the main forcing factors responsible for repositioning the shoreline which ran along the strike slip afonso bezerra fault at an angle of approximately 35 to the present coast in the early mid holocene were as follows 1 tectonic activity along the strike slip afonso bezerra fault 2 fast inundation of the shallow paleo valley embayment during the last pulse of holocene transgression ca 8000 cal yr bp 3 advance of the assu river mouth through accretion of fluvial bay head delta and costal drift sediments and 4 sheltering of embayment by barrier islands which permitted a widespread development of mangrove forest during the last 3 millennia the estimated rate of progradation of the assu estuary that led to the present stage of terminal infilling is in the order of 3 4 m yr

the tsiolkovskiy crater landslide the moon an lroc view abstract evidence suggests that the lobate flow feature that extends 72 km outward from the western rim of tsiolkovskiy crater is a long runout landslide this landslide exhibits three possibly four morphologically different parts likely caused by local conditions all of these plus the ejecta of tsiolkovskiy crater and its mare fill are approximately of the same crater model age i e 3 55 0 1 ga the enormous size of this landslide is unique on the moon and is a result of a combination of several geometric factors e g its location relative to fermi crater and that tsiolkovskiy crater was an oblique impact that produced an ejecta forbidden zone on its western side schultz 1976 the landslide formed in this ejecta free zone as the rim of tsiolkovskiy collapsed and its debris flowed across the relatively smooth flat floor of fermi crater in this location it could be easily identified as a landslide and not ejecta its mobility and coefficient of friction are similar to landslides in valles marineris on mars but less than wet or even dry terrestrial natural flows this suggests that the mars landslides may have been emplaced dry the high density of small craters on the landslide is likely an illusion caused by the effects of age related differences in regolith thickness on crater morphology and the presence of the abundant young circular secondary craters produce by debris ejected from distant fresh craters

a scheme for improving scatterometer surface wind fields a method is presented for improving quikscat surface wind fields the university of washington planetary boundary layer model is used to retrieve a surface pressure field from any swath of quikscat surface wind vectors an alternate set of surface wind vectors is computed from the newly calculated pressure field the latter can be smoothed and the process can be iterated new surface wind vectors can be calculated where ambiguity removal fails and where measurements are missing the present methodology preserves boundary layer dynamics and is an improvement over a statistical filter

ocean surface pressure fields from satellite sensed winds abstract the university of washington s planetary boundary layer model is inverted to use remotely sensed satellite scatterometer derived surface winds as input to calculate maritime surface pressure fields the analysis of three different synoptic storm situations is performed using the model and is then compared to conventional national weather service analyses agreement is good isolation of the pbl secondary flow stratification and thermal wind effects in the model revealed that each may be significant under certain conditions however the model shows sensitivity to the thermodynamic features only in a general sense and even a neutral stratification solution gives a good approximation the high density of the scatterometer data produces mesoscale hundreds of kilometers dynamic details which cannot be confirmed by conventional data at this stage

scaling behaviour of clay rich submarine debris flows we perform a statistical study of submarine debris flows based on recent data from the storegga area off the western coast of norway due to the high quality of the data and the uniformity of materials the data from the storegga database are far less dispersed than world wide compilations available so far allowing for a fit with good statistical significance we find that both the run out and the ratio between fall height and run out are best described as a power law function of the volume for small to moderate volumes visco plastic models are able to reproduce the power law in contrast to granular frictional models however either progressive mixing of the shear layer with ambient water or hydro planing must be invoked in order to explain the extreme run out distances of larger debris flows

evolution of estuarine facies in a tidal channel environment sw spain evidence for a change from tide to wave domination abstract the transition from tide to wave dominated environments is documented in holocene estuaries along the mesotidal coast of huelva southwestern spain this transition is a consequence of the decreasing tidal prism caused by estuarine siltation a process favoured by the inherited morphology of the prior fluvial valleys the domingo rubio tidal channel is a small estuary adjacent to the mouth of two wave dominated estuaries along the coast of huelva coring and vibracoring of both surficial and subsurface sediments allow the distinction of six lithofacies that form five depositional environments 1 salt marsh 2 active channel margin 3 washover fan 4 tidal channel and 5 estuarine channel the facies architecture reveals the infilling process of the tidal channel due to the interaction of both waves and tides wave activity is registered in the elongation of the spit whereas tidal action produces facies associations characteristic of tide dominated estuaries the recent history of this estuary records three successive stages 1 an initial tide dominated open marine environment beginning at 3090 60 years b p with strong tidal currents in very energetic channels displaying a straight meandering straight morphology 2 a wave dominated period during which waves transport sand into the inner estuary and also along the mouth spit at about 2500 years b p and 3 a second tide dominated stage from 300 80 years b p onward during which weaker tidal currents distribute the sediment four factors controlled the transition from tide to wave domination 1 the relief formed during deposition 2 the decreasing tidal prism 3 the inner facies distribution versus those of the outlet and 4 the seaward spit elongation of adjacent estuaries

depositional history of estuarine infill during the last postglacial transgression gulf of cadiz southern spain abstract the late pleistocene and holocene evolution of the estuaries in the gulf of cadiz is interpreted for the first time using drill cores logs trenches and 38 new radiocarbon data and the results compared with the shelf the odiel tinto and guadalete rivers deposited conglomerates during a highstand that did not reach the present sea level dated at ca 25 30 ka isotopic stage is 3 corresponding to a relatively humid period in the area rivers incised these coarse grained deposits during the last main lowstand at ca 18 ka when sea level dropped to 120 m and the coastline lay 14 km seawards from the present the erosional surface is a sequence boundary and the flooding surface of the postglacial eustatic rise overlain by the valley fill deposits of the transgressive and highstand phases of the last fourth and fifth order depositional sequences recognised in the shelf the first marine influence in the estuaries during the transgression occurs at 25 30 m at ca 10 000 years bp according to fossil assemblages the transgressed basins changed from brackish to more open marine as the sea rose until ca 6500 years bp when it reached the maximum flooding and the sandy estuarine barriers ceased to retrograde toward the muddy central basins then the rate of eustatic rise decreased drastically and the estuarine filling followed a two fold pattern governed by the progressive change from vertical accretion to lateral centripetal progradation at ca 4000 years bp the fluvial input surpassed the already negligible rate of rise causing partial emergence of tidal flats and spit barriers in the largely filled estuarine basins prevalence of coastal progradation upon vertical accretion at ca 2400 years bp caused accelerated expansion of tidal flats and rapid growth of the sandy barriers further changes since the 16th century reflect widespread anthropic impacts

wind and pressure fields near tropical cyclone oliver derived from scatterometer observations the results of this study demonstrate that the surface wind velocity and pressure fields derived from spaceborne scatterometers are useful in monitoring the location and intensity of tropical cyclones satellite borne microwave scatterometers can penetrate the cloudy core regions of tropical cyclones to resolve the circulation in detail over data sparse regions the location of the cyclone observed by the ers 1 scatterometer is very close to that revealed in geostationary meteorological satellite images the surface winds provided by the ers 1 scatterometer are used here with a modified two layer planetary boundary layer model which includes effects of curvature stability and secondary flow to derive surface pressures near tropical cyclone oliver the curvature effect is found to be more significant than stability and secondary flow which are crucial in deriving accurate surface pressure fields in midlatitudes

effects of debris flow composition on runout depositional mechanisms and deposit morphology in laboratory experiments predicting debris flow runout is of major importance for hazard mitigation apart from topography and volume runout distance and area depends on debris flow composition and rheology but how is poorly understood we experimentally investigated effects of composition on debris flow runout depositional mechanisms and deposit geometry the small scale experimental debris flows were largely similar to natural debris flows in terms of flow behavior deposit morphology grain size sorting channel width depth ratio and runout deposit geometry lobe thickness and width in our experimental debris flows is largely determined by composition while the effects of initial conditions of topography i e outflow plain slope and channel slope and width and volume are negligible we find a clear optimum in the relations of runout with coarse material fraction and clay fraction increasing coarse material concentration leads to larger runout however excess coarse material results in a large accumulation of coarse debris at the flow front and enhances diffusivity increasing frontal friction and decreasing runout increasing clay content initially enhances runout but too much clay leads to very viscous flows reducing runout runout increases with channel slope and width outflow plain slope debris flow volume and water fraction these results imply that debris flow runout depends at least as much on composition as on topography this study improves understanding of the effects of debris flow composition on runout and may aid future debris flow hazard assessments

landslide hazard assessment by smoothed particle hydrodynamics with spatially variable soil properties and statistical rainfall distribution rainfall induced landslide has caused significant damage to structures and casualties in the past decades and it is of great importance to assess the post failure behavior of slopes this study pr

the perfect debris flow aggregated results from 28 large scale experiments 1 aggregation of data collected in 28 controlled experiments reveals reproducible debris flow behavior that provides a clear target for model tests in each experiment 10 m3 of unsorted water saturated sediment composed mostly of sand and gravel discharged from behind a gate descended a steep 95 m flume and formed a deposit on a nearly horizontal runout surface experiment subsets were distinguished by differing basal boundary conditions 1 versus 16 mm roughness heights and sediment mud contents 1 versus 7 percent dry weight sensor measurements of evolving flow thicknesses basal normal stresses and basal pore fluid pressures demonstrate that debris flows in all subsets developed dilated coarse grained high friction snouts followed by bodies of nearly liquefied finer grained debris mud enhanced flow mobility by maintaining high pore pressures in flow bodies and bed roughness reduced flow speeds but not distances of flow runout roughness had these effects because it promoted debris agitation and grain size segregation and thereby aided growth of lateral levees that channelized flow grain size segregation also contributed to development of ubiquitous roll waves which had diverse amplitudes exhibiting fractal number size distributions despite the influence of these waves and other sources of dispersion the aggregated data have well defined patterns that help constrain individual terms in a depth averaged debris flow model the patterns imply that local flow resistance evolved together with global flow dynamics contradicting the hypothesis that any consistent rheology applied we infer that new evolution equations not new rheologies are needed to explain how characteristic debris flow behavior emerges from the interactions of debris constituents

observations of grain scale interactions and simulation of dry granular flows in a large scale flume a series of 30 tests on dry granular flows were performed using a large scale flume under varying source volumes and basal friction conditions to capture grain scale interactions and their impact o

estuarine fluvial floodplain formation in the holocene lower tagus valley central portugal and implications for quaternary fluvial system evolution abstract we present a brief synthesis of the quaternary fluvial record in the lower tagus basin central portugal concentrating on factors controlling infill and incision the holocene part of the record forms the focus of this paper and guides the questioning of the basic assumptions of the established quaternary fluvial evolution model in particular the link between sea level change and fluvial incision deposition we suggest that several incision aggradation phases may have occurred during glacial periods major aggradation events may overlap with cold episodes while incision appears to concentrate on the warming limb of climate transitions the complex stratigraphy of the quaternary record in the lower tagus valley is influenced by repeated base level and climate changes this paper submits the first chronostratigraphic framework for valley fill deposits in the lower tagus area sea level rise forced aggradation and controlled deposition of the fine grained sedimentary wedge underlying the low gradient lower tagus floodplain investigations have focused on the lower muge tributary where rapidly aggrading estuarine and fluvial environments were abruptly established 8150 cal bp as sea level rose base level at the valley mouth controlled the upstream extent of the fine grained backfill tidal environments disappeared abruptly 5800 cal bp when the open estuary at the muge confluence was infilled by the tagus river the decrease and final still stand of sea level rise led to floodplain stabilisation with peat 6400 5200 cal bp and soil formation 5200 2200 cal bp localised renewed sedimentation 2200 200 cal bp is linked to human activity

scaling and design of landslide and debris flow experiments abstract scaling plays a crucial role in designing experiments aimed at understanding the behavior of landslides debris flows and other geomorphic phenomena involving grain fluid mixtures scaling can be addressed by using dimensional analysis or more rigorously by normalizing differential equations that describe the evolving dynamics of the system both of these approaches show that relative to full scale natural events miniaturized landslides and debris flows exhibit disproportionately large effects of viscous shear resistance and cohesion as well as disproportionately small effects of excess pore fluid pressure that is generated by debris dilation or contraction this behavioral divergence grows in proportion to h3 where h is the thickness of a moving mass therefore to maximize geomorphological relevance experiments with wet landslides and debris flows must be conducted at the largest feasible scales another important consideration is that unlike stream flows landslides and debris flows accelerate from statically balanced initial states thus no characteristic macroscopic velocity exists to guide experiment scaling and design on the other hand macroscopic gravity driven motion of landslides and debris flows evolves over a characteristic time scale l g 1 2 where g is the magnitude of gravitational acceleration and l is the characteristic length of the moving mass grain scale stress generation within the mass occurs on a shorter time scale h gl 1 2 which is inversely proportional to the depth averaged material shear rate a separation of these two time scales exists if the criterion h l

a physical model based field wise and self contained algorithm for removing directional ambiguities of ocean surface winds retrieved from scatterometer measurements an algorithm is introduced to remove the directional ambiguities in ocean surface winds measured by scatterometers which requires scatterometer data only it is based on two versions of pbl planetary boundary layer models and a low pass filter a pressure field is first derived from the median filtered scatterometer winds is then noise filtered and is finally converted back to the winds respectively by an inverted pbl model a smoothing algorithm and a pbl model the derived wind field is used to remove the directional ambiguities in the scatterometer data this new algorithm is applied to hurricane eugene and produces results comparable to those from the current standard ambiguity removal algorithm for nasa jpl seawinds project which requires external numerical weather forecast analyses data

physical and biogenic aspects of backbarrier sedimentary sequences georgia coast u s a abstract configuration of the present georgia coast with its broad expanses of salt marsh and intricate tidal drainages behind pleistocene holocene barrier islands implies the filling of an extensive backbarrier lagoonal system however riverine and salt marsh estuaries dominate the modern depositional setting and reconstructed vertical sequences suggest that backbarrier filling was accomplished by estuarine processes backbarrier sediments exhibit considerable diversity in grain size and physical and biogenic sedimentary structures principal sediment textures include clean to muddy coarse and fine sand mud and to a lesser extent shells pebbles and mud and bedrock clasts physical sedimentary structures many modified by bioturbation include large scale cross bedding trough and planar with graded sets small scale crossbedding ripple lamination and flaser wavy and lenticular bedding laminated to interbedded sand and mud and rare pebble or shell beds ebb oriented structures predominate over flood oriented ones except in upper reaches of riverine estuaries biogenic sedimentary structures typically are diverse and abundant characteristic lebensspuren include polychaete dwelling tubes decapod and polychaete burrows ray holes and bioturbate textures imparted by amphipods ophiuroids bivalves and anemones patterns of bioturbation are controlled to some extent by sediment type salinity levels and rates of deposition and physical reworking of sediments although intensity of bioturbation generally increases seaward bioturbate textures are more readily preservable in the lower energy middle reaches of estuaries because of numerous local pleistocene sediment sources and local variations in hydrographic regimes the stratigraphic record of salt marsh estuaries differs relatively little from that of riverine estuaries the basic sequence in ascending order typically consists of 1 channel lag and or channel fill deposits 2 estuarine accretionary beds 3 point bar tidal flat and shoal sediments and 4 channel margin and salt marsh deposits

can the collapse of a fly ash heap develop into an air fluidized flow reanalysis of the jupille accident 1961 a fly ash heap collapse occurred in jupille liege belgium in 1961 the subsequent flow of fly ash reached a surprisingly long runout and had catastrophic consequences its unprecedented degree of fluidization attracted scientific attention as drillings and direct observations revealed no water saturated zone at the base of the deposits scientists assumed an air fluidization mechanism which appeared consistent with the properties of the material in this paper the air fluidization assumption is tested based on two dimensional numerical simulations the numerical model has been developed so as to focus on the most prominent processes governing the flow with parameters constrained by their physical interpretation results are compared to accurate field observations and are presented for different stages in the model enhancement so as to provide a base for a discussion of the relative influence of pore pressure dissipation and pore pressure generation these results show that the apparently high diffusion coefficient that characterizes the dissipation of air pore pressures is in fact sufficiently low for an important degree of fluidization to be maintained during a flow of hundreds of meters

slow unconfined spreading of a mudflow mudflows are natural highly concentrated water clay grain mixtures that flow in mountain streams after long or intense rainy periods and may cause considerable damage if they overflow on the alluvial fan the possibility of predicting the extent of these flows on the basis of material and flow parameters is examined the simplest realistic case of a yield stress mudflow moving through a narrow open channel followed by a wide long plane is considered it is demonstrated that the unconfined flow of a yield stress fluid over an inclined plane cannot be uniform even in steady state the flow width should increase continuously from the channel exit a complete treatment of the flow equation on the basis of the long wave approximation including an appropriate three dimensional expression for the constitutive equation makes it possible to establish a system of equations from which flow characteristics at any point longitudinal and lateral mean velocities and fluid depth can be deduced in particular for a herschel bulkley fluid with a flow index of 1 3 it is found that the lateral extent will increase proportionally to the distance from the channel exit to the power 9 20 and that in the sheared part the fluid depth in a cross section will have a parabolic distribution experiments have been carried out with fine mud suspensions at different solid fractions whose rheological behavior is similar to that of natural mudflows the theory is in fair agreement with experimental data concerning fluid depth distribution but systematically overestimates lateral extent by 30 this is certainly due to the fact that the assumption of lateral extent much smaller than flow length is not respected in our tests

large scale landslide simulations global deformation velocities and basal friction the cause of the apparent small friction exhibited by long runout landslides has long been speculated upon in an attempt to provide some insight into the matter this paper describes results obtained from a discrete particle computer simulation of landslides composed of up to 1 000 000 two dimensional discs while simplified the results show many of the characteristics of field data the volumetric effect on runout preserved strata etc and with allowances made for the two dimensional nature of the simulation the runouts compare well with those of actual landslides the results challenge the current view that landslides travel as a nearly solid block riding atop a low friction basal layer instead they show that the mass is completely shearing and indicate that the apparent friction coefficient is an increasing function of shear rate the volumetric effect can then be understood with all other conditions being equal different size slides appear to travel with nearly the same average velocity however as the larger landslides are thicker they experience smaller shear rates and correspondingly smaller fractional resistance

shallow viscoplastic flow on an inclined plane evolving viscoplastic flows upon slopes are an important idealization of many flows in a variety of geophysical situations where yield stress is thought to play a role for such models asymptotic expansions suitable for slowly moving shallow fluid layers lubrication theory reduce the governing equations to a simpler problem in terms of the fluid thickness we consider the version of the theory for fluids described by the herschel bulkley constitutive law and provide a variety of solutions to the reduced equation both numerical and analytical for extruded inclined domes we derive the characteristic temporal behaviour of measures of the dome s dimensions

objective delineation of lahar inundation hazard zones a new method of delineating lahar hazard zones in valleys that head on volcano flanks provides a rapid objective reproducible alternative to traditional methods the rationale for the method derives from scaling analyses of generic lahar paths and statistical analyses of 27 lahar paths documented at nine volcanoes together these analyses yield semiempirical equations that predict inundated valley cross sectional areas a and planimetric areas b as functions of lahar volume v the predictive equations a 0 05v 2 3 and b 200v 2 3 provide all information necessary to calculate and plot in

applicability of power law for describing the rheology of soils of different origins and characteristics the rate dependent rheological behaviour of soils of different origins and characteristics was studied and the applicability of the power law model was examined the studied soils were divided into

experimental study of the grain flow fluid mud transition in debris flows abstract we have performed a series of laboratory experiments that clarify the nature of the transition between fluid mud and grain flow behavior the surface velocity structure and the speed of the nose of debris flows in channels with semicircular cross sections were measured with several cameras and visual tracers while the mass flow rate was recorded using a load cell at the exit chamber other rheological tests were used to calculate independently the yield strength and matrix viscosity of the debris flow mixture shear rates were varied by nearly an order of magnitude for each mixture by changing the channel radius and slope shear rates were significantly higher than expected 6 55 s 1 given the modest slopes examined 10 7 15 2 the large values were primarily a result of the concentration of shear into narrow bands between a central nondeforming plug and the sidewall as a result the shear rate of interest was calculated by using the width of the shear band and the plug velocity as oppose

on satellite scatterometer model functions satellite scatterometer model functions are the empirical correlations between observed backscatter and geophysical parameters one problem is the choice of surface truth for the latter currently buoy data and general circulation model surface analyses have been used to establish 10 m neutrally stratified wind model functions the correlation between backscatter and surface winds has been the foundation of the scatterometers the backscatter is anisotropic with respect to wind direction allowing wind direction information to be derived from multiple looks at the same patch of ocean here the evolution of a model function for the pressure gradient hence surface geostrophic wind is given the european center for medium range weather forecasts surface pressure analyses are used to establish the pressure based model function there are limitations and advantages to both geophysical data sets

giant landslides topography and erosion abstract distributions of slope angles in tectonically active mountain belts point to the development of threshold conditions where hillslopes attain a critical inclination or height at which they fail readily because of limitations in material strength it has been proposed that hillslopes adjust to rapid uplift and bedrock incision through an increase in the rate of relief limiting landsliding rather than gradual slope steepening here we test this concept by investigating the relationship between mean local relief h which we take to be a proxy of long term erosion rates e and the occurrence of over 300 of the largest v 10 8 m 3 terrestrial landslides on earth we find that nearly two thirds of these giant landslides have occurred in the steepest 5 of the earth s land surface where relief is close to its proposed upper strength limit they are primarily located in deeply incised valleys along fault bounded fringes of active mountain belts and in volcanic arcs this distribution coincides with areas of high long term erosion rates 4 mm yr 1 confirming that giant landslides contribute to rapid denudation of mountains most of the eroded volume is concentrated in the smallest but steepest parts of mountain belts and volcanic arcs first order estimates of minimum erosion rates accomplished by the largest landslides are 0 01 mm yr 1 these rates are between 1 and 10 of the late pleistocene to holocene mean erosion rates in a given area importantly the landslide erosion rates show a nonlinear increase with mean local relief suggesting that the contribution of giant landslides in total and per event increases significantly with increasing overall erosion rates however giant landslides also occur in areas of lower than average relief h 300 700 m irrespective of whether threshold hillslopes have developed or not factors contributing to these failures include soft rocks extensive low angle discontinuities high rates of fluvial bedrock incision and tectonically driven deformation and slope loading

interpretation of scatterometer ocean surface wind vector eofs over the northwestern pacific abstract satellite scatterometer winds over the northwestern pacific were analyzed with the vector empirical orthogonal function veof method the hilbert huang transform hht a newly developed non linear and non stationary time series data processing method was also employed in the analysis a combination of european remote sensing satellite ers 1 2 scatterometer nasa scatterometer nscat and nasa s quick scatterometer quikscat winds covering the period from january 1992 to april 2000 and the area of 0 50 n 100 148 e constitutes the baseline for this study the results indicate that annual cycles dominate the two leading veof modes the first veof shows the east asian monsoon features and the second represents a spring autumn oscillation we removed the annual signal from the data set and calculated the interannual veofs the first interannual veof represents the interannual variability existing in the spring autumn oscillation the temporal mode is correlated with the southern oscillation index soi but has a half year lag with respect to the soi the spatial mode of the first interannual veof reflects the response of the tropical and extratropical winds to enso events the second interannual veof is another enso related mode and the temporal veof mode is correlated with the soi with a correlation coefficient of 0 78 revealing the wind variability over mid latitudes which is associated with enso events further analysis indicated that the wind variability over the coast of east asia represents anomalies of a hadley cell the quasi biennial oscillation qbo was found in the temporal mode indicating and verifying that the qbo in the wind fields is related to enso events the third veof shows the interannaul variability in the winter summer mode and displays the interannual variability of the east asian monsoon the three leading interannual veofs are statistically meaningful as confirmed by a significance test

grain size segregation and levee formation in geophysical mass flows 1 data from large scale debris flow experiments are combined with modeling of particle size segregation to explain the formation of lateral levees enriched in coarse grains the experimental flows consisted of 10 m3 of water saturated sand and gravel which traveled 80 m down a steeply inclined flume before forming an elongated leveed deposit 10 m long on a nearly horizontal runout surface we measured the surface velocity field and observed the sequence of deposition by seeding tracers onto the flow surface and tracking them in video footage levees formed by progressive downslope accretion approximately 3 5 m behind the flow front which advanced steadily at 2 m s 1 during most of the runout segregation was measured by placing 600 coarse tracer pebbles on the bed which when entrained into the flow segregated upwards at 6 7 5 cm s 1 when excavated from the deposit these were distributed in a horseshoe shaped pattern that became increasingly elevated closer to the deposit termination although there was clear evidence for inverse grading during the flow transect sampling revealed that the resulting leveed deposit was strongly graded laterally with only weak vertical grading we construct an empirical three dimensional velocity field resembling the experimental observations and use this with a particle size segregation model to predict the segregation and transport of material through the flow we infer that coarse material segregates to the flow surface and is transported to the flow front by shear within the flow head coarse material is overridden then recirculates in spiral trajectories due to size segregation before being advected to the flow edges and deposited to form coarse particle enriched levees

satellite based midlatitude cyclone statistics over the southern ocean 1 scatterometer derived pressure fields and storm tracking 1 a wavelet based method is described for incorporating swaths of surface pressure derived from scatterometer measurements into surface pressure analyses obtained from the european centre for medium range weather forecasts ecmwf the resulting modified pressure fields are used to identify low pressure centers over the southern ocean and to build statistics of midlatitude cyclones during 7 years of the seawinds on quikscat operational period july 1999 to june 2006 the impact of the scatterometer derived pressure swaths is assessed with a statistical analysis of cyclone characteristics central pressure radius depth performed in parallel on the ecmwf and on the modified pressure fields more low pressure centers 5 10 depending on the season are identified with the modified pressure fields in particular incipient lows captured earlier than ecmwf and more short lived mesoscale cyclones with a life span less than 4 days the cyclones identified with the modified pressure fields are characterized by lower central pressure and tighter isobars on average a parallel spectral analysis reveals 1 additional energy at scales less than 2000 km in the modified pressure fields

the impact of seasat a scatterometer data on the numerical prediction of the queen elizabeth ii storm the development of the queen elizabeth ii storm from 1200 ut on september 9 1978 to 0000 ut on september 11 1978 is forecast with a limited area fine resolution 100 km numerical weather prediction model forecasts from initial conditions that include and exclude seasat scatterometer surface winds are performed when the seasat winds are allowed to influence the upper levels of the atmosphere a large positive impact is found

estuarine sedimentation on the eastern shore of nova scotia abstract vibracored sedimentary sequences and microfauna foraminifera were studied in lawrencetown lake a small wavedominated estuary with minor fluvial input located on the eastern shore of nova scotia seven lithofacies were identified on the basis of sedimentological characteristics microfaunal assemblages and stratigraphic relationships these lithofacies can be grouped into three associations which define estuarine basin fill channel cut and fill and channel bypass subenvironments within the estuary system facies relationships indicate a cyclic pattern of estuarine sedimentation controlled by fluctuating local sediment supply superimposed upon a regional transgression

changes in sedimentation trends in sw iberia holocene estuaries spain abstract an analysis of sedimentation rates during the holocene in estuaries in the southwestern coast of the iberian peninsula using depth age diagrams reveals the existence of two distinct phases the first between ca 10 000 and 6500 cal bp still in the transgressive phase yields values of sedimentation rates of 5 mm yr the second phase extends after the maximum transgressive ca 6500 cal bp until the present with sedimentation rates of 1 5 2 mm yr these results support the idea that marine sedimentation began during the transgressive phase and continued during the highstand phase far beyond the time of the transgressive maximum as postulated in some previous papers

runout of dry granular avalanches laboratory experiments on granular avalanching of dry sands and gravels reveal a consistent pattern of runout distance varying with fall height fall slope and volume of material for volumes rangi

mobility of long runout rock flows a discrete numerical investigation summary in the perspective of studying the mobility and deposit geometry of long runout flows discrete numerical simulations of model granular avalanches over simple topography are performed analysing the behaviour of the ratio h l depending on the parameters varied in the simulations we show its poor sensitivity to the topographic parameters namely the initial height of the flowing mass and the slope on the contrary a correlation between h l and the frictional properties of the material is established however the existence of variations of the effective friction induced by the dynamics are not reflected by the value of h l as an alternative to the h l description of the flow behaviour we propose a new scaling for the runout distance taking into account the lateral extension l0 of the relief forming the normalized runout l l0 and defining the aspect ratio a of the topography we show the dependence of l l0 on a thus generalizing previous analysis of martian data analysing the correlation between the normalized runout and the front velocity for the numerical simulations we show how l l0 depends both on the frictional properties of the material and on the dynamics of the flow this result suggests the necessity of evaluating the lateral extension of the relief l0 in the case of natural flows in order to define a horizontal travel index including the topography in an attempt to better understand the flow dynamics analysing the deposit for both simulations and real flow data we evidence a common behaviour suggesting that the geometric factors prevail in the spreading dynamics irrespective of the details of the flow context and conditions we moreover assert the relevance of discrete simulations to the discussion of real cases

buried sandbodies within present day estuaries atlantic coast of france revealed by very high resolution seismic surveys abstract studies of sandbanks within estuaries and macrotidal bays are critical for management of those coastal environments where human activity concentrates they are also excellent analogues of reservoirs new very high resolution vhr seismic profilers are now available for studying at the outcrop resolution scale sandbodies in very shallow water we present here a vhr seismic study constrained by vibrocores repetitive bathymetric surveys and radiocarbon dating which provide evidence of buried sandbodies in mixed tide and wave influenced estuaries of the french atlantic coast the three selected buried sandbodies are chosen because they are located at various water depths and have different internal architecture and outer shape they include 1 a very shallow water around 2 m under low tide elongated nearshore sandbody emplaced during the last centuries 2 a 6 to 7 m deep elongated nearshore sandbody dated to 2965 30 bp and 3 sandwaves lying around 17 m of water depth over the top of a large rounded shape sandbody dated to 5260 30 bp deepest 6 and 17 m sandbodies are interpreted as remnants of lower sea levels and thus transgressive sandbodies all those sandbodies are buried under estuarine mud which have been mainly emplaced during the last millenium such major sedimentary transition from basal sand to upper mud is assumed to record a major environmental change in relation to both natural infilling of estuaries climate change and increasing human activities anthropogenic perturbations are however believed to be the most important factor they have mainly consisted of land reclamation and are responsible for 1 rapid infilling of tidal bays 2 tidal prism and tidal current energy decreases and 3 deposition of muddy sediments upon sandbodies

channeled flow analytic solutions laboratory experiments and applications to lava flows although channeled lava flows are common in basaltic volcanism relationships between channel morphology eruption and emplacement parameters and lava properties are not well understood several models have commonly been used to constrain these relations but they have not been well tested on natural or simulated lava flows over a wide range of parameter space here we test the accuracy and assumptions of a moderately simple analytic rectangular channel solution by comparing the behavior of well controlled laboratory polyethylene glycol peg channeled flows to the analytic solution for isothermal steady newtonian flow in a rectangular channel with constant dimensions this analytic solution agrees well with laboratory measurements volumetric effusion rates q m3 s 1 calculated from the analytical model using measured peg flows as input yield ratios of qcalculated qpumped of 0 2 to 3 6 and flow rates calculated from a best fit surface velocity profile to measured velocities give more accurate ratios of 0 8 to 1 2 we find a very weak dependence of solution accuracy on slope attributable to flow front effects within the laboratory flows we subsequently apply the solution to several subaerial and submarine terrestrial flows as well as extraterrestrial channeled flows over a wide range of flow parameters viscosity ranges and flow rates obtained using measured channel dimensions and assumed lava properties are plausible interestingly the resulting extraterrestrial estimates of viscosities and flow rates tend to fall closer to known terrestrial measurements and estimates of channel flow than to previous planetary estimates we therefore suggest that the analytic newtonian rectangular channel flow model is a more appropriate physical model for many channeled terrestrial and planetary flows than the newtonian infinite sheet flow and approximation to bingham channel flow widely used previously

seafloor environmental changes resulting from nineteenth century reclamation in mishou bay bungo channel southwest japan this study reconstructed environmental changes to the seafloor associated with reclamation in mishou bay bungo channel japan based on measurements of sediment grain size organic matter and sulfur contents of surface sediments and data from sediment cores grain size within sediment cores from the middle of mishou bay decreased from the beginning of the 1800s to the 1900s in contrast a grain size profile from the river mouth shows a gradual increase in grain size up through the sediment core these changes in grain size indicate a decrease in tidal current velocity within the middle of the bay and that the delta system is gradually prograding from the river mouth records of organic matter composition and sulfur contents indicate that the effect of the river on seafloor sedimentation became stronger during the nineteenth century these changes are related to reclamation during the late 1700s and 1800s the decrease in sea area resulting from reclamation probably led to a decrease in tidal prism and current velocity it is likely that the increasing effect of river water on sedimentation is associated with reclamation related progradation of the river delta system