perturbation solution for dam break floods a solution for the complete and instantaneous collapse of a dam in a prismatic infinitely long sloping channel is found by using the method of matched asymptotic expansions the outer solution is a kinematic wave approximation and an inner solution that includes a depth gradient term in the momentum equation is calculated for the region near the moving kinematic shock front the reservoir is modeled with a point mass source and the solution is believed to become asymptotically valid after the shock front has advanced about four reservoir lengths downstream a comparison with experiment shows good qualitative agreement but more comparisons with experiment should be made in order to assess the qualitative accuracy of the solution

fluvial response to paleo equatorial climate fluctuations during the late paleozoic ice age the maritimes basin of atlantic canada preserves a 12 km thick stratigraphic succession deposited within a low latitude predominantly continental setting during the late paleozoic this paper examines the utility of using such successions for paleoclimate analysis with specific reference to changes in fluvial style modern rivers in the subhumid and semiarid tropics preserve a suite of features that are distinct from those in humid and arid environments these features include an abundance of sedimentary structures formed under froude transcritical to supercritical flow conditions and the presence of in situ vegetation growing within the channel environment this fluvial style is indicative of prolonged low flow conditions punctuated by intense precipitation events in a strongly seasonal climatic setting fluvial channel bodies within the maritimes basin preserve a remarkably similar style compared with these modern systems suggesting that a subhumid strongly seasonal paleoclimate was the dominant imprint on parts of the preserved successions strongly seasonal deposits are concentrated within four discrete stratigraphic intervals e1 e4 ranging in duration from 2 to 6 m y these intervals are correlated across the entire basin and between basins characterized by markedly different tectonic regimes which suggests that a coherent regional climate signal is recorded intervals are separated by deposits characteristic of humid and arid river systems and the alternation between these different fluvial styles implies that several pronounced long term changes in precipitation and runoff regimes occurred during the carboniferous within the region furthermore these intervals broadly coincide with major periods of southern hemisphere glaciation which suggests that glaciation had a profound and controlling effect on paleotropical climate

towards a better understanding of riparian zone water table response to precipitation surface water infiltration hillslope contribution or pressure wave processes determining how riparian zone hydrological conditions may change in response to precipitation in various geomorphic settings is critical to determine the occurrence of hot moments of biogeochemical transformations for phosphorus nitrogen sulfate mercury and greenhouse gases in these systems the author investigate water table response to precipitation at a high temporal resolution 15 min in a riparian zone located in a deeply incised glacial till valley 20 m with approximately 2 m of alluvium over a confining layer in indiana usa during storms larger water table fluctuations approximately 100 cm occurred near the stream than near the toe slope 10 25 cm a quick rise in water table near the stream occurred for all storms with partial flow reversals occurring for three of seven storms the quick rise of the water table near the stream was associated with a decrease in hillslope water contributions to the stream during storms and the development of a water table down valley gradient for most storms water table fluctuations groundwater flow velocities and electrical conductivity data indicated that riparian zone water table response to precipitation was primarily regulated by pressure wave processes regardless of the storm high water tables persisted for at least 2 days after the cessation of precipitation although this suggests that high resolution precipitation data may be useful to quantify hot moments of biogeochemical transformation associated with high water tables in riparian zones precipitation data alone are not sufficient to correctly estimate the magnitude of riparian water table level changes during storms copyright 2011 john wiley sons ltd

transition from arc to intraplate magmatism associated with backarc rifting evolution of the sikhote alin volcanism k ar dates and chemical compositions of lavas in sikhote alin far east russia demonstrate marked secular variation in lava chemistry and suggest a linkage between magmatism and the major tectonic opening of the japan sea backarc basin lavas having typical arc magma chemistry were produced at 40 25 ma in the eastern part of sikhote alin a conspicuous volcanic hiatus is revealed in the region at 25 20 ma which is contemporaneous with the period of the major rifting of the backarc basin subduction related magmatism may have been switched off by an oceanward retreat of the arc trench system in contrast intraplate type lavas with typical hotspot magma compositions have dominated magmatism in both the eastern and western sikhote alin since 20 ma and occupy the eastern margin of the cenozoic intraplate magmatism in the ne asian continent

linking granulites silicic magmatism and crustal growth in arcs ion microprobe zircon u pb ages from the hidaka metamorphic belt japan there is no consensus as to how the extreme metamorphic conditions required to form granulites are attained or how these rocks relate to crustal growth and differentiation processes studying young granulites offers two advantages the tectonic setting is likely to be well constrained and the ambiguities that result from overprinting by younger metamorphic events are potentially avoided we report the first ion microprobe u pb zircon ages for orthopyroxene bearing granulites tonalites and gabbros of the cenozoic hidaka metamorphic belt hokkaido japan to clarify the magmatic metamorphic connection in this area the data support a two stage evolution for this terrane which is attributed to episodes of supra subduction zone magmatism late eocene and back arc extension early miocene we relate granulite facies metamorphism and garnet orthopyroxene tonalite generation to mafic magma under accretion and lithosphere thinning due to the opening of the japan sea at 19 ma the hidaka granulites are thus among the youngest exposed granulites on earth and manifest the thermal response to continental growth

modeling subsurface stormflow on steeply sloping forested watersheds five mathematical models for predicting subsurface flow were compared to discharge measurements made by hewlett and hibbert 1963 on a uniform sloping soil trough at the coweeta hydrologic laboratory the models included one and two dimensional finite element models based on the richards equation a kinematic wave model and two simple storage discharge models based on the kinematic wave and boussinesq assumptions the simple models simulated the subsurface response and water table positions as well as the more complex models based on the richards equation and were much more economical to use from the point of view of computational costs such models have features that would allow them to be incorporated into more complex watershed models thus placing hydrologic prediction on a more physically correct and less empirical footing

mathematical simulation of interdependent surface and subsurface hydrologic processes it has become popular with some hydrologists to consider runoff produced by rainfall intensities in excess of soil infiltration capacity horton excess and runoff produced by rain falling on saturated soil zones saturation excess to be alternative or competitive models for describing surface runoff on the contrary we contend with freeze 1972 that these two mechanisms along with subsurface stormflow are three parts of a continuum of hydrologic response that are controlled by the relative properties of the soil and the rainfall we introduce a model which trades some of the generality of the freeze 1972 hillslope model for increased efficiency by selecting efficient approximations for key elements in hillslope hydrodynamics infiltration and movement in the unsaturated flow zone the hillslope is considered to consist of two soil layers with the lower soil capable of restricting vertical flow at the interface to create a perched aquifer and subsurface stormflow the slope of the interface is arbitrary a kinematic method for routing unsaturated vertical flow is described and is linked consistently with a modern analytically derived infiltration model which operates when rainfall exceeds surface saturated hydraulic conductivity ks the model is used to demonstrate several of the relationships between rainfall flux soil hydraulic properties hillslope geometry and runoff characteristics the model is also applied to simulate experimental data from a hillslope in western australia subsurface stormflow recessions are demonstrated to be affected by the ratio ks ql anisotropy and spatial distribution of saturated hydraulic conductivity ks where ql is the rate of loss from the perched aquifer vertical growth of the saturated zone depth is demonstrated to have a potentially greater effect on runoff than horizontal movement in cases where anisotropy and or slope is not severe

kinematic wave approximation to infiltration into soils with sorbing macropores infiltration into soils with macropores is treated as two domain flow the first domain is the soil matrix in which water is subjected to capillarity and infiltration is approached by philip s sorptivity concept the second domain is the soil macropore system in which water moves only under gravity and flow is approached by kinematic wave theory a sink function with respect to flow in the macropore system accounts for water sorption by the soil matrix the two domain flow model is then applied to infiltration into a block of undisturbed soil containing macropores

modelling gully erosion for a small catchment on the chinese loess plateau the rolling hills region of the chinese loess plateau is one of the areas with the highest erosion rates on earth a striking feature of this area is the occurrence of many large permanent gullies a 3 5 km2 catchment was selected to study the processes of erosion and to adapt the storm based limburg soil erosion model lisem to the conditions prevailing on the loess plateau part of this work consisted of mapping and measuring the largest gully headcuts the amount of loose soil material beneath the headcuts was also estimated observations suggest that gully headcuts are relatively stable i e do not migrate rapidly but that gullies can nevertheless produce significant amounts of sediment during overland flow events erosion of headcuts occurs mainly by soil falls in between storms the loose soil material produced by these soil falls accumulates on the gully bottom as the lisem simulates storm erosion the development of gullies over time can be ignored and only the amount of material produced by them during runoff events needs to be studied a digital elevation model dem was used to estimate the position of existing gully heads by applying an adapted form of the montgomery and dietrich science 255 1992 826 index using the assumption that headcuts are vertical it is possible to calculate headcut height from the slope angle map a simple stability model which assumes soil falls on gully headcuts to be a function of soil moisture content and headcut height was applied this daily based model can then be used to simulate the accumulation of loose soil material below the headcut the results show that while the dem is not accurate enough to allow the detection of individual headcuts this method can be used to produce a reasonable estimate of the amount of loose soil material available a map showing the amount of loose soil material accumulated can then serve as input for a storm based erosion model such as lisem

wetting front advance and freezing of meltwater within a snow cover 1 observations in the canadian arctic in a naturally stratified snow cover the movement of meltwater into dry snow is complicated by the interaction of the wetting front with stratigraphic horizons field observations showed that when the wetting front reached premelt stratigraphic horizons water ponded at the interface and then flow fingers developed and penetrated the lower stratum the flux in these fingers which was increased to about twice that of the surface flux was used to feed water to the impeding horizons where it froze to form ice layers these ice layers were the major source of latent heat released within the snow cover and they were responsible for the warming of the snow and the underlying soil these continuous ice layers grew only at stratigraphic boundaries because of this ice layer growth the wetting front advance was retarded and the arrival of meltwater at the snow cover base was significantly delayed owing to a cold substrate the strong heat flux from the snow into the soil delays the warming of the snow cover and limits runoff after the snow is isothermal at 0 c by the refreezing of soil infiltration and the development of a basal ice layer

one dimensional bed wave movement in lowland rivers we show that recent measurements in the east fork river wyoming of annual gravel wave translation annual bedload transport and annual variations in riverbed cross sectional area can be described to within a factor of 2 by using the gradowczyk characteristic velocity for bed waves to describe gravel wave translation the engelund hansen formula for bedload transport and a duboys like formula for changes in cross sectional area no free parameters are needed

analysis of river wave types in this paper we consider long period shallow water waves in rivers that are a consequence of unsteady flow river waves result from hydroelectric power generation or flow control at a dam the breach of a dam the formation or release of an ice jam and rainfall runoff processes the saint venant equations are generally used to describe river waves dynamic gravity diffusion and kinematic river waves have been defined each corresponding to different forms of the momentum equation and each applying to some subset of the overall range of river hydraulic properties and time scales of wave motion however the parameter ranges corresponding to each wave description are not well defined and the transitions between wave types have not been explored this paper is an investigation into these areas which are fundamental to river wave modeling the analysis is based on the concept that river wave behavior is determined by the balance between friction and inertia the saint venant equations are combined to form a system equation that is written in dimensionless form the dominant terms of the system equation change with the relative magnitudes of a group of dimensionless scaling parameters that quantify the friction inertia balance these scaling parameters are continuous indicating that the various river wave types and the transitions between them form a spectrum additional data describing the physical variability of a river and wave are incorporated into the analysis by interpreting the scaling parameters as random variables this probabilistic interpretation provides an improved estimate of the friction inertia balance further insight into the continuous nature of wave transitions and a measure of the reliability of wave type assessments near a transition case studies are used to define the scaling parameter ranges representing each wave type and transition and to provide data with which to evaluate the usefulness of the analysis for general application

sediment provenance in a tropical fluvial and marine context by magnetic fingerprinting of transportable sand fractions the sources and fluxes of sediment to the great barrier reef lagoon from northeastern australian rivers have been the subject of much concern and study with the large catchments of the burdekin and fitzroy rivers thought to be the key sources at present here the utility of newly developed magnetic fingerprinting methods for identifying sediment provenance both onshore and offshore and in association with individual large flood events is investigated within the burdekin catchment sediments are mobilized from different subcatchments by runoff generated by intense localized rainfall events magnetic measurements were made on untreated and acid treated samples of river channel sediments within the burdekin river subcatchments and from the estuarine and inner shelf depocentres of burdekin river sediments the acid treatment removes all discrete magnetic particles and coatings and leaves magnetic inclusions protected within host silicate grains as the basis of the measured magnetic signature of a sample the magnetic properties of the acid treated samples display statistically distinct sediment provenance groupings sand samples from the upper burdekin river appear magnetically distinct from samples from tributaries of the burdekin e g hann creek fanning river and also from nearby coastal rivers including the haughton suspended sand samples from a burdekin flood event in 2000 appear to have a different source compared with those from floods in 1998 and 1999 comparisons of the terrestrial acid treated sand fractions with the same acid treated sand size fractions from transects taken offshore suggest that the surface sediments in upstart bay and bowling green bay have different sources some of these sources are as yet unidentified but may represent the unsampled lower discharge south western burdekin subcatchments and or along shore drift of sand from the south perhaps even from the fitzroy river over millennial timescales of cyclone pumping the magnetic inclusion method precludes any obfuscation or confounding of sediment source which might arise from hydraulic sorting and or post depositional magnetic diagenesis or authigenesis

obstacle marks produced by flow around stranded ice blocks during a glacier outburst flood jokulhlaup in west greenland the effects of glacier ice block grounding on the morphology and sedimentology of proglacial fluvial outwash were examined during a glacier outburst flood or jokulhlaup near sondre stromfjord west greenland observations made during and after the 1987 jokulhlaup both on the surface of an ice contact delta and within a confined valley sandur plain provided information about the formation of ice block obstacle marks and the significance of these bedforms for sandur morphology and sedimentology flow directions determined from obstacle mark morphology have been used successfully to chart flow direction changes on the falling limb of the jokulhlaup maximum flow depths for scour around stranded ice blocks may be given by 0 5 0 9 times the diameter of the ice block as estimated from the depth of scour the height of the obstacle shadow or the extent of ice block meltout sediments minimum flow depths can be represented by the height of the obstacle shadow above the mean bed level the internal composition of the shadow indicates the ability of the flow to transport various sizes of material into the lee of obstacles ice block obstacle marks within the distal portion of the sandur initiated waning stage channel change proximal and lateral erosion around stranded ice blocks extended downstream from the ice block forming chute channels which then captured waning stage flows resulting in significant bar incision with associated deposition of lobate or deltaic deposits it is suggested that ice block obstacle marks are important in terms of channel morphology channel morphological change and their usefulness as palaeohydrological indicators

unsteady overland sedimentation abstract sediment flux to fluid flow in a rill is represented with physically based models for simultaneous sediment entrainment detachment deposition settlement and lateral inflow and is shown to be an improvement over existing concepts for describing low sediment concentrations unsteady flow and sedimentation in overland rills are then described by continuity equations and approximations for flow entrainment and transport capacity the equations are reduced for an assumed rill pattern on an overland plot to one dimensional equations of motion which do not utilize sheet flow approximations the method of characteristics solution to these equations for uniform rainfall excess yields both the hydrograph rising limb and uniform crest and a three part sediment concentration graph with a predicted time lag between peaks of these graphs the resulting model allows substitution of reasonable parameter values as opposed to the requirements of conventional sheet flow approximations sediment concentration is given by steady uniform transport capacity equations only when the flow is steady uniform no lateral inflow over infinite channel length or recirculating flume or when the steady uniform transport capacity concentration in the rill is equal to the lateral inflow concentration it then appears that rill topographies develop to the point where the latter condition is satisfied boundary conditions on the first derivative of sediment concentration with time suggest constraints on the form of the equations for fluid flow entrainment and transport capacity which agree well with empirical evidence general observations on the solution are made which outline the expected nature of overland sedimentation

caesium 137 in sandy sediments of the river loire france assessment of an alluvial island evolving over the last 50 years recent sedimentological and morphological evolution of an island in the river loire france was investigated using the 137cs method this study describes the morphological adjustment of the island in the last 50 years which corresponds to the increased bed incision of this sandy multiple channel environment because of among other things the increase in sediment extraction up to 1995 the results show that some 137cs can be retained by sandy particles potentially in clay minerals forming weathering features included in detrital sand grains from a morphological perspective significant lateral erosion can be observed in the upstream part of the island while a weak lateral accretion occurs in its downstream section data about 137cs and aerial photographs show that the morphology of the island margins has undergone significant changes leading to a lateral migration while the centre of the island has remained relatively stable or is slowly eroding the migration of the island depends on 1 the withdrawal of inherited preincision morphological units such as levees or the development of new units such as a channel shelf 2 water and sediment supply from surrounding channels during flood events 3 preferential sediment trapping 20 mm year 1 from the presence of riparian vegetation on the bank of the secondary channel that is subject to narrowing the sedimentological and morphological response of the island in the context of incision of the loire river bed is expressed mainly by lateral migration and secondarily by a low vertical adjustment

a screening model for nonaqueous phase liquid transport in the vadose zone using green ampt and kinematic wave theory in this paper a screening model for flow of a nonaqueous phase liquid napl and associated chemical transport in the vadose zone is developed the model is based on kinematic approximation of the governing equations for both the napl and a partitionable chemical constituent the resulting governing equation is a first order quasi linear hyperbolic equation to which the generalized method of characteristics can be applied this approach generally neglects the contribution to the napl flux from capillary pressure gradients during infiltration under ponded conditions or when the napl flux exceeds the maximum effective conductivity of the soil the effect of capillary suction is included in the model through the usage of the green ampt model all of the resulting model equations are in the form of ordinary differential equations which are solved numerically by a variable time step runge kutta technique results from a simple column experiment were used to evaluate the vadose zone flow model assumptions independently measured parameters allow simulation without calibration of the model results the match of the model to the data suggests that the model captures the qualitative behavior of the experimental system and is capable of an acceptable degree of quantitative agreement

hydraulic causes for basin hydrograph skewness it has been suggested that hydrograph skewness depends on the relative dominance between hillslope and channel network transport processes where the former ones make the hydrograph positively skewed while the latter tends to make it negatively skewed more recently however the role of river hydraulics in shaping the hydrograph has been highlighted we present a set of numerical modelling experiments using a hydrodynamic model of river networks in which we investigate how channel hydraulics influence the shape of the hydrograph particularly its skewness we further investigate the influence of baseflow rainfall intensity cross section geometry and basin scale on unit hydrograph response we show that river hydraulics has a decisive role because positively skewed hydrographs may occur even when water inputs to the river network are negatively skewed and in catchments whose width function is also negatively skewed we show additional results related to the effect of the degree of non linearity in the relationship between celerity and discharge the effects of baseflow and rainfall intensity these further confirm that hydraulic factors may be decisive in determining hydrograph shape

the role of discharge variability in the formation and preservation of alluvial sediment bodies abstract extant planform based facies models for alluvial deposits are not fully fit for purpose because they over emphasise plan form whereas there is little in the alluvial rock record that is distinctive of any particular planform and because the planform of individual rivers vary in both time and space accordingly existing facies models have limited predictive capability in this paper we explore the role of inter annual peak discharge variability as a possible control on the character of the preserved alluvial record data from a suite of modern rivers for which long term gauging records are available and for which there are published descriptions of subsurface sedimentary architecture are analysed the selected rivers are categorized according to their variance in peak discharge or the coefficient of variation cvqp standard deviation of the annual peak flood discharge over the mean annual peak flood discharge this parameter ranges over the rivers studied between 0 18 and 1 22 allowing classification of rivers as having very low 0 90 annual peak discharge variance deposits of rivers with very low and low peak discharge variability are dominated by cross bedding on various scales and preserve macroform bedding structure allowing the interpretation of bar construction processes rivers with moderate values preserve mostly cross bedding but records of macroform processes are in places muted and considerably modified by reworking rivers with high and very high values of annual peak discharge variability show a wide range of bedding structures commonly including critical and supercritical flow structures abundant in situ trees and transported large woody debris and their deposits contain pedogenically modified mud partings and generally lack macroform structure such a facies assemblage is distinctively different from the conventional fluvial style recorded in published facies models but is widely developed both in modern and ancient alluvial deposits this high peak variance style is also distinctive of rivers that are undergoing contraction in discharge over time because of the gradual annexation of the channel belt by the establishment of woody vegetation we propose that discharge variability both inter annual peak variation and flashiness may be a more reliable basis for classifying the alluvial rock record than planform and we provide some examples of three classes of alluvial sediment bodies representing low intermediate and high very high discharge variability from the rock record that illustrate this point

kinematic properties of mudflows on mt st helens summarized are findings of a computer based study of the mud flows on mt st helens following its eruption on may 18 1980 analyses were made of the start up dynamics and flow of mud down various drainages of the mountain and of the surge wave generation in swift reservoir when the mudflow down east pine creek entered the reservoir viscosities of mudflows in the muddy creek and pine creek drainages were evaluated in order to establish a basis for general analysis of mudflow phenomena starting with estimates of snow deposition on the mountain and incorporating the characteristics of the pyroclastic blast of the eruption initiation of flow was approximated subsequent flow down different drainages was modeled and time sequencing of the flows into swift reservoir was compared with measured reservoir elevations recorded on the morning following the eruption additional kinematics of the flows were compared with corresponding field measured data where possible

bottomset architecture formed in the troughs of dunes and unit bars abstract bottomsets are formed in the troughs of migrating bedforms the flow and sediment dynamics downstream of bedforms differ and consequently the thickness grain size and internal structure of bottomsets vary greatly a classification of the controls on bottomset formation is proposed related to two and three dimensional processes flow and sediment unsteadiness and pre existing deposits structures and deposits created by flow and sediment unsteadiness as well as pre existing deposits are also considered in relation to changes they can induce in subsequent trough processes the classification is illustrated by observations from laboratory flumes the modern burdekin river australia and the rock record the roaches grit england and hawkesbury sandstone australia in bottomset examples described in this paper internal variability both vertically and laterally was much greater than that within the dominant foreset component complex compound structures were created by the interaction and predominance of different bottomset controls this combined with their high preservation potential makes them a highly useful paleoenvironmental indicator bottomset variation e g changes in the abundance of mud laterally will influence the permeability heterogeneity of fluvial reservoir rocks bottomsets formed under relatively steady conditions are likely to be laterally extensive and have similar characteristics over their entire length they may act as significant barriers to vertical flow conversely bottomsets generated in unsteady regimes tend to be highly variable potentially creating conduits between cross bed sets aiding inter set permeability

variations in character and preservation potential of vegetation induced obstacle marks in the variable discharge burdekin river of north queensland australia abstract vegetation induced obstacle marks are described from dalrymple bend in the burdekin river of queensland australia and their preservation potential is discussed the bend is divided into a sand and gravel covered lower bar and a vegetated upper bar obstacle marks comprising an erosional scour and a depositional sediment tail are recognised on the lower bar and the lower margin of the upper bar two types of obstacle marks are dominant in the lower part of the lower bar sediment tail dominated obstacle marks associated with inclined trees of melaleuca argentea silver leaved paperbark and comparatively small obstacle marks around stranded driftwood obstacle marks in the upper part of the lower bar are formed around grass clumps armoured with mud and gravel at the lower margin of the upper bar scours and gravelly sediment tails are recognised around mature tall trees in these cases the scour is 4 m in width and covered with alternating beds of fine sand and mud among the obstacle marks described sediment tail dominated obstacle marks around groves of m argentea have the highest preservation potential obstacle marks in the lower margin of the upper bar are also considered to have high preservation potential obstacle marks around stranded driftwood have the lowest preservation potential obstacle marks around grass clumps survive more than 1 year but their long term preservation potential is nonetheless low implications for the stratigraphic record are also discussed

is hydrology kinematic a wide range of phenomena natural as well as man made in physical chemical and biological hydrology exhibit characteristics similar to those of kinematic waves the question we ask is can these phenomena be described using the theory of kinematic waves since the range of phenomena is wide another question we ask is how prevalent are kinematic waves if they are widely pervasive does that mean hydrology is kinematic or close to it this paper addresses these issues which are perceived to be fundamental to advancing the state of the art of water science and engineering copyright 2002 john wiley sons ltd

asymptotic solution for dam break on sloping channel the kinematic wave approximation is used to obtain a closed form solution for the catastrophic failure of a dam upon a wet sloping channel the solution shows that increasing the initial water depth upon the channel increases both the time and distance required for the resulting shock to approach any given depth downstream it is also shown that the kinematic wave solution becomes valid only after the shock travels a certain distance downstream and that increasing the initial water depth upon the channel increases this distance

fossil trees in ancient fluvial channel deposits evidence of seasonal and longer term climatic variability it has been established that large numbers of certain trees can survive in the beds of rivers of northeastern australia where a strongly seasonal distribution of precipitation causes extreme variations in flow on both a yearly and longer term basis in these rivers minimal flow occurs throughout much of any year and for periods of up to several years allowing the trees to become established and to adapt their form in order to facilitate their survival in environments that experience periodic inundation by fast flowing debris laden water such trees notably paperbark trees of the angiosperm genus melaleuca adopt a reclined to prostrate downstream trailing habit have a multiple stemmed form modified crown with weeping foliage development of thick spongy bark anchoring of roots into firm to lithified substrates beneath the channel floor root regeneration and develop in flow parallel linear groves individuals from within flow parallel linear groves are preserved in situ within the alluvial deposit of the river following burial and death four examples of in situ tree fossils within alluvial channel deposits in the permian of eastern australia demonstrate that specialised riverbed plant communities also existed at times in the geological past these examples from the lower permian carmila beds upper permian moranbah coal measures and baralaba coal measures of central queensland and the upper permian newcastle coal measures of central new south wales show several of the characteristics of trees described from modern rivers in northeastern australia including preservation in closely spaced groups these properties together with independent sedimentological evidence suggest that the permian trees were adapted to an environment affected by highly variable runoff albeit in a more temperate climatic situation than the modem australian examples it is proposed that occurrences of fossil trees preserved in situ within alluvial channel deposits may be diagnostic of environments controlled by seasonal and longer term variability in fluvial runoff and hence may have value in interpreting aspects of palaeoclimate from ancient alluvial successions c 2001 elsevier science b v all rights reserved

dam break solution a closed form solution is obtained for a dam break problem in which the reservoir dam breach and downstream channel all have different widths the reservoir outflow is calculated by using a quasi steady flow approximation and downstream flood depths are calculated by using the kinematic wave approximation an investigation into the validity of these two approximations leads to constraints that must be placed upon applications of the solution a numerical example shows that maximum downstream flood depths decay relatively slowly because of storage contained within the upstream reservoir

preferential flow and the generation of runoff 1 boundary layer flow theory approaches to soil water flow which are based on the theory of potential flow often overestimate either the volume of flow or the response time at the hillslope scale when their results are compared with observations macropore flow is frequently thought to be the reason for the discrepancy between observations and model performance the expression macropore flow is considered to be too restricting it confines the rapid flow and transport processes to the easily observed channels concealing the more general question as to what degree potential flow theory adequately describes flow in porous media the application of potential flow theory to infiltration leads to the richards equations only when hydrodynamic dispersion of soil water and capillary potential are perfectly correlated in this paper a boundary layer infiltration model is presented which is based on kinematic theory it is also expanded to lateral flow in a sloping soil

meltwater movement in a deep snowpack 2 simulation model a numerical simulation model is developed describing the one dimensional flow of meltwater in a snowpack based on established methods of modeling unsaturated groundwater flow the results of field observations of snowmelt and meltwater flow are used to determine parameters describing the hydraulic properties of the snowpack and surface energy balance measurements are used as input to the model tests of the performance of the model show a high sensitivity to the saturated hydraulic conductivity of the snowpack and to liquid water content of the snow saturated hydraulic conductivity can be measured with acceptable precision by simple field methods however measurement of liquid water content is more difficult and constitutes the major limitation affecting calibration of the model the model is relatively insensitive to exponents in the power law equations relating conductivity capillary pressure and liquid water content meltwater wave speeds predicted by the model are somewhat slower than those observed in the field observations of snowpack layering and horizontal inhomogeneity of flow suggest that these features affect transient storage of meltwater and consequently cause meltwater wave speeds to differ from those predicted by a one dimensional model

analytical model of surface flow on hillslopes based on the zero inertia equations abstractcoming from the zero inertia zi equations an analytical model to describe sheet flow phenomena with a special focus on rainfall runoff processes is developed a slight modification of the zi equations which draws upon the concept of a momentum representative cross section of the moving water body leads after comprehensive mathematical calculus to an analytical solution describing essentially one dimensional shallow overland flow in a test series the analytical zi model is applied together with three numerical models one based on the saint venant equations one on the kinematic wave equations and another one on diffusion wave equations the test application refers to a typical rainfall runoff situation i e rather shallow overland flow on a hillslope as a consequence of excess rainfall contrary to the analytical model the comparative analysis clearly shows the difficulties of the numerical solutions in terms of exactness and robustness when approaching typical shallow water depths th

on subsurface stormflow predictions with simple kinematic theory for saturated and unsaturated flows this paper provides analytical solutions for some simple cases of subsurface stormflow the solutions are based on kinematic approximations in both unsaturated and saturated zones solutions for rising falling and partial equilibrium hydrographs are given the analytical model has been applied to data collected on a hillslope of the east twin brook catchment mendip united kingdom measured and predicted hillslope hydrographs were in good agreement

throughflow and solute transport in an isolated sloping soil block in a forested catchment a 3m wide by 9m long by 1m deep soil block on a forested hillslope near orono me was isolated by excavation of encircling trenches a sprinkler system for application of water and potassium bromide tracer was constructed over the plot outflow was collected at six locations with troughs experiments were conducted at application rates of 2 5 5 and 10 cm h 1 pulses of tracer were applied subsequent to attainment of steady flow and breakthrough curves were measured at all outflow points recession limbs of outflow hydrographs exhibited distinct breaks when plotted on semilogarithmic axes indicating drainage from at least two distinguishable pore size classes or flow pathways solute breakthrough curves were dominated by a single peak travel times of solute were inversely related to the application rate a secondary peak in the outflow curve which is inconsistent with transport theories for a homogeneous soil was observed in all cases this second peak is unexplained but is conceptually consistent with the notion of transport in at least two pore size classes an undisturbed soil core diameter of 30 cm and length of 40 cm was sprinkled at the same rates as was the soil block using methylene blue as tracer in the last run drainage hydrographs and visual examination of dye stains in the block indicated also at this smaller scale that flow and transport are controlled by preferred paths in the soil paths that cannot be morphologically distinguished from the surrounding soil matrix theoretical explanations of processes on such hillslopes need to account for this fact

flood behaviour of the burdekin river tropical north queensland australia strongly seasonal rainfall in north queensland australia causes extremely variable fluvial discharge and tropical cyclones commonly produce high magnitude short duration floods in the burdekin river catchment 129 500 km2 of eastern queensland rapid runoff and channel floodplain configuration lead to very fast flood wave speeds up to 4 34 m s 1 calculated the large catchment and varying tropical cyclone paths result in extreme variations in flood history at different sites changes in channel conditions bed elevation vegetation bedforms sediment surface character in successive events combined with complex rainfall patterns and highly unsteady flow make flood estimates extremely difficult because of the short duration of flow events and very rapid rate of change in discharge during individual events sediment transport rate bedforms and bed elevation change continuously for most of the year the channel is occupied by an underfit stream but this small perennial stream does not significantly rework the deposits or change channel form before the next major discharge event consequently there is little channel form recovery between major discharge events successive events have very variable size and consequently the bedforms and channel morphology are normally out of equilibrium with the flow and record the result of the most recent major events high magnitude floods transport coarse sediment onto the floodplain and the short duration of flooding and rapid runoff results in relatively low preservation of mud in the channel or overbank environment the holocene flood deposits include thick coarse sand and medium sand units and generally thin fine grained units

sedimentological effects and stratigraphic implications of a rare high stage flow in an evolving braided to anabranching stream with riparian woodland abstract low frequency 1 in 25 years high stage flows on the south platte and upper platte rivers in nebraska usa during september october 2013 produced sedimentary effects that are unaccounted for in depositional models of that fluvial system being superimposed on a historically recent trend of channel belt abandonment and encroachment of woody vegetation these outcomes are even more useful for comparison with the wider sedimentary record rooted vegetation particularly riparian trees played a major role in determining where erosion and sedimentation occurred outside of the main perennially flowing channels effects of the 2013 event include 1 small pebble to cobble sized gravel in various bar top and flood channel settings 2 common current or sediment shadows including streamlined sediment shadow bars several meters or more in length which formed downstream from rooted trees and logjams 3 sand lobes that prograded into densely wooded abandoned parts of the historical channel belt at angles of as much as 85 from average downstream flow 4 large scours some approaching 2 m in depth many of which formed behind trees near the diffluences of flood channels and the main channel 5 deposits of sand that were baffled by nonwoody or shrubby vegetation in the abandoned channel belt and 6 local accumulations of large woody debris in front of rooted trees as cross flood channel dams and rarely as walls alongside flood channels in an aggrading system these features should be preserved as a distinctive set of sedimentary structures which may be interpretable as evidence for episodic major flows in a system in which woody vegetation has encroached widely onto the channel belt

kinematic subsurface stormflow this paper builds on the analysis of henderson and wooding 1964 in comparing simplified models of subsurface stormflow for the case of a sloping soil mantle in which the hydraulic conductivity is constant throughout it is shown that models based on a kinematic wave formulation may be good approximations for those based on the extended dupuit forchheimier assumptions for values of the nondimensional parameter 4i cos k sin2 less than about 0 75 in terms of predicting both water table profiles and subsurface stormflow hydrographs by using this critical value of the range of values of slope angle and saturated hydraulic conductivity for which the kinematic approximation is valid can be specified a comparison is made with slope angles and hydraulic conductivities at field sites where subsurface stormflow has been shown to be an important component of catchment storm response it is concluded that the kinematic approximation may be useful for cases of practical interest

a fast simplified model for predicting river flood inundation probabilities in poorly gauged areas the capability of a simple kinematic storage model ksm is analysed to be used as a tool for a decision support system for the evaluation of probability inundation maps in near real time in poorly gauged areas ksm simulates the floodplain as a storage and assumes no exchange of momentum with the channel for the in bank flow the storage is modified through a coefficient for taking the variations of channel cross sections into account the generalized likelihood uncertainty estimation approach is used for addressing the probability flood maps along with their associated uncertainties the model is tested on two river reaches along the tiber river in central italy where observed inundation maps are available for two recent flood events despite the inherent uncertainties present in the input data and in the model structure the results show that the model reproduces reasonably well in terms of both precision and accuracy the observed inundated areas tests were performed at different digital elevation model resolutions showing a small effect of the geometry on the maximum performance obtained the very low computational times the parsimony of the model and its low sensitivity to the quality of the geometry representation of the channel and the floodplain makes ksm very appealing for flood forecasting and early warning system applications in poorly gauged and inaccessible areas copyright 2014 john wiley sons ltd

a distribution function approach to water flow in soil macropores based on kinematic wave theory kinematic wave theory is adapted to gravity driven flow in narrowly defined macropore groups the frequency distribution of macropore conductance b dimensions l t 1 is obtained by superimposing the predicted drainage hydrographs from the individual groups of macropores and matching predicted outputs to observed drainage hydrographs the time period over which this concept applies is limited to about 1 5 times the duration of the water input to the soil surface the drainage hydrographs from four different soils using three different measuring devices were analyzed accordingly the analysis suggests that between 10 2 and 0 2 of the input is required to supply water to the macropore system while a parameter controlling losses to the matrix varies over only a small range

meltwater movement in a deep snowpack 1 field observations the flow of meltwater through a snowpack can be described by darcy s law and by a set of equations relating conductivity capillary pressure and liquid water content which are similar to the equations governing unsaturated groundwater flow field observations were conducted which were designed to test the applicability of the unsaturated flow equations to the description of meltwater movement at the scale of a small watershed simple instrumentation was used to measure capillary pressure and meltwater flux rates this was supplemented with energy and water balance measurements for the study watershed observations of surface snowmelt meltwater flux and streamflow for the snowmelt period confirm the nature of meltwater flow as described by the unsaturated flow equations and illustrate the controlling influence of snowpack hydraulics on the streamflow hydrograph observed speeds of the meltwater wave front in the snowpack average about 0 22 m h 1 and capillary pressures and kinematic wave speeds observed are comparable to those reported in other deep snow environments the difficulty of obtaining reliable liquid water content measurements is identified as a major limitation in the determination of hydraulic properties of the snowpack

kinematic models for soil moisture and solute transport the kinematic theory of soil moisture and solute transport in the vertical direction for unsaturated groundwater recharge is considered the general theory of kinematic models is reviewed and applied for an isolated wetting event wherein the soil starts at and eventually drains to field capacity analytical expressions are developed for the water content and moisture flux as a function of depth and time the approach is extended for an arbitrary sequence of surface flux or water content boundary conditions the transport of a solute with a general nonlinear sorption isotherm is also considered it is shown that for the general isotherm the vertical displacement of a solute isochore during an arbitrary wetting sequence depends only on the total depth of water infiltrated and not on how the infiltration rate varies with time

modified kinematic model application to bed forms the kinematic wave theory originally developed for flood routing purposes is generalized in such a way that kinematic dynamic couplings are accounted for due to various forces the equations of continuity for water and sediment are transformed into a typical mass transport equation including convection diffusion and source terms each of these terms is shown to represent dynamic contributions of certain forces on the kinematics of the motion the theory is used to explain various aspects of bed form phenomena a numerical modeling method based on the proposed dynamic wave equation is suggested

kinematic wave approximation to the transport of escherichia coli in the vadose zone threshold values for macropore flow parameters that are thought to be critical in the transport of microbial suspensions through macroporous soils were established through the application of a kinematic wave approach to bacterial breakthrough curves according to the presented examples moisture content w and conductance b in the macropore systems of four different soils had simultaneously to exceed 0 015 m3 m3 and 0 1 m s respectively before substantial microbial breakthrough was observed at the bottom of undisturbed columns of macroporous soils with lengths ranging from 0 21 to 0 32 m the application of these thresholds in a modeling approach to large scale flow revealed that hardly any microbes can be transported deeper than 2 3 m in soils when durations and intensities of naturally occurring precipitation events were entered into the model it was also shown however that prolonged or intensified water input to the soil surface may efficiently carry microbes deeper than 100 m into the vadose zone

crustal structure volcanism and opening mode of the ulleung basin east sea sea of japan abstract a study of the ulleung basin in the southwestern east sea sea of japan based on single and multi channel seismic reflection profiles and ocean bottom seismometer obs data suggests that the basin formed largely by pull apart opening and the deep northern basin is underlain by thicker than normal oceanic crust 10 km thick probably formed during the earliest stage of seafloor spreading volcanic activity in association with basin opening occurred over much of the basin but it ceased first in the south while it continued in the north until recently the principal evidence for pull apart opening includes 1 an overall rhomboidal shape of the basin consisting of two basement lows and a median high known to be characteristic of pull apart basins 2 the location and orientation of the major volcanic sources suggesting more or less n s opening and 3 the strike slip fault system along the western basin margin which appears to have guided the pull apart opening the lack of extensional deformation along the western basin margin which would have been prevalent if sw japan had rotated away from the korean peninsula as suggested by paleomagnetic data is also not in favor of the alternative rotational opening of the basin the absence of graben and rift topography in the acoustic basement in the deep northern ulleung basin is indicative of the non brittle or ductile nature of the crust tau p analysis of the obs data reveals that the igneous crust consists of upper and lower layers with velocities typical of oceanic layers the velocity depth profiles with a two gradient velocity structure is also characteristic of oceanic crust however the lower layer is much thicker than oceanic layer 3 and the change of velocity gradient which occurs at around 6 5 km s in typical oceanic crust occurs at about 6 km s suggesting that the crust is not a typical oceanic crust the meager basin size and short opening period may suggest that the basin opening did not lead to the formation of full fledged oceanic crust but instead resulted in embryonic or incipient oceanic crust thickened by upper mantle thermal perturbations evoked by rifting

fluvial processes in a forested anastomosing river flood partitioning and changing flow patterns in an effort to further our understanding of multiple channel systems this paper presents data on the flood response of channels in one of the last wooded semi natural anastomosing systems in europe the gearagh ireland is characterized by hundreds of small islands separated by interconnected channels of low slope these include channels that cross islands at right angles to the main flow and blind anabranching channels islands are relatively stable and wooded with evidence of division by channel erosion and growth by in channel sedimentation four active zone cross profiles were surveyed each containing between seven and 13 channels velocities were measured in several channels before and during two separate floods from these observations channels have been categorised into three types fast shallow and trapezoidal slow deep and more irregular and flood channels during the floods interchannel flows were caused by variations in water surface elevations due to backing up behind debris dams and it is suggested that this is the origin of the anomalous cross island channels and one cause of island division another potential cause of island division blind anabranching channels is the result of concentrated bank scour between root masses biotic components such as debris dams tree root masses and tree throw pits play a key role in the partitioning of flow and cause variations in channel velocities and the overbank velocity distribution the implications of these observations for channel pattern maintenance are briefly discussed

discussion of computing nonhydrostatic shallow water flow over steep terrain the authors are to be commended for their valuable and unique comparison of experimental data for clear water dam break floods on steep slopes and for their nonhydrostatic shallow water model the dam break experiments down a steep slope at the usgs outdoor laboratory logan and iverson 2007 mimic the behavior of natural flows and shed light on different mechanisms inertia viscous dissipation pressure gradient that control the flow dynamics the discusser has studied roll wave development in dam breaks and similar problems on steep slopes restricted to relatively long timescales for which the kinematic regime is reached and the authors fine results present a great opportunity to consider some interesting features of the dam break wave it is understood that there is a lack of validation of asymptotic solutions for dam break waves on steep slopes based on the kinematic wave approximation lighthill and whitham 1955 with both experimental data and numerical simulations even the earlier solutions by hunt 1982 1984 and weir 1983 for shallow slopes have not yet been validated as discussed by hunt 1984 a comparison with experiment shows good qualitative agreement but more comparisons with experiment should be made in order to assess the qualitative accuracy of the solution this question remains still unresolved e g singh 2002 and references therein to address this point the value of enhanced gravity g must

vertical mixing of coarse particles in gravel bed rivers a kinematic model burial of transported material in gravel bed rivers was examined using several hundred magnetically tagged particles burial depth of individual particles varies with no simple relation to particle size distributions of burial depth of particles were examined by considering observed burial depth of individual size groups of all mobile particles and of all tagged particles including static ones simple single peak flow events yielded exponential distributions of burial depth of mobile particles distributions with secondary peaks were obtained from large and multipeak events season long results were skew peaked with a tendency toward uniformity an m layer model is developed to account for the variation of frequency of burial depth of particles based on the assumptions that the burial depth of particles in a simple event is exponentially distributed and the proportion of particles which change vertical position from a given layer is constant from event to event the model is elaborated for varying mixing rates varying scour depths and variable behavior of different size classes after many events the material is uniformly distributed throughout all layers in conformity with field experience

wetting front advance and freezing of meltwater within a snow cover 2 a simulation model a simulation model is developed which incorporates the effect of flow fingers at the leading edge of the wetting front ice layer growth within and at the base of the snow cover and meltwater infiltration into the underlying frozen soils the model results demonstrated that ice layers grow rapidly over a 24 to 36 hour period due to the conduction of heat into the snow and underlying soil sufficient water is frozen as ice layers to slow the finger wetting front and to account for the rapid snow and soil warming wetting front advance and ice layer growth were found to be sensitive to snow temperature thermal conductivity volume of flow in the fingers and irreducible water saturation simulation of a warm snow cover showed that with reduced ice layer growth the flow fingers were able to transmit rapidly water to the snow cover base before the entire snow cover was wet in the arctic situation the soil was sufficiently cold to ensure basal ice growth throughout the melt period basal ice growth was found to be sensitive to soil infiltration length of the growing period and the snowmelt rate as a result of the negative soil heat flux all meltwater is not available for runoff until both the liquid and thermal requirements of the snow and soil have been satisfied

current crescents formed by marine algae valonia sp a new record of obstacle marks lacking preservation of obstacles obstacle marks formed around non permanent tools commonly occur on the beach faces of lower long sand island and sagar island two tidal islands in the ganga river estuary india the marine globose algae valonia sp which bloom profusely in the waters of the bay of bengal during winter are deposited on beach faces after being carried by wave swash and then act as impermeable obstacles in the path of wave backwash this creates around the globose algal bodies u shaped or crescentic marks 2 3 cm in width with arms 1 3 cm in length the globose vesicles are soon broken up by external forces or by forces of surface tension leaving crescentic marks around a circular filamentous impression the crescents always open toward the direction of wave backwash these structures may prove useful not only for interpreting the palaeoslope and palaeocurrent directions but also for recognizing the palaeoecology

cenozoic episodic volcanism and continental rifting in northeast china and possible link to japan sea development as revealed from k ar geochronology abstract cenozoic volcanic rocks in northeast china comprise part of the volcanic belt of the western circum pacific rim and represent one of the presently active tectono magmatic regions of the world over 590 volcanoes with erupted basalts covering an area of 50 000 km 2 are exposed in the songliao graben and particularly on its flanks k ar dating of the volcanic rocks sampled from a selection of eruption sites over the region reveals that the volcanism occurred episodically through the entire cenozoic corresponding to the tectono magmatic interactions particularly between the india eurasia and pacific plates the volcanism initiated in the songliao graben in late cretaceous 86 ma and migrated flankward since 28 ma the magmatic propagation shows three major stages intimately associated with the evolution of japan sea and related to the geodynamic forcing of the india eurasia collision prior to japan sea rifting volcanic eruptions were restricted to the songliao basin during japan sea opening volcanism migrated into the lateral belts after cessation of japan sea opening at 15 ma volcanism with greatest intensity occurred on both flanks particularly along the yi yi fault system around 14 13 ma and subsequently the fu mi fault between 11 and 7 ma continuing this trend of migration eruptions scattered further away from the songliao basin in the last 4 5 ma we suggest that the cenozoic volcanic belt in northeast china and the japan sea backarc basin are competitive parts in the eastern marginal magmatic system of the eurasian plate the early stage of the volcanism in the songliao basin may have resulted from mantle upwelling beneath the songliao bohai basin belt rifting of the ne faults and relatively weak intensity of volcanism in northeast china during japan sea opening could be attributable to the lithospheric breakup in the japan sea and spreading of japan sea the subsequent strong volcanism in northeast china after cessation of the japan sea opening implicates the easiest pathway for the melts of the magmatic system in the plate margin the diversified volcanism in scattered localities during the quaternary may indicate localized melting processes or notable modifications in smaller sized individual domains and possibly a magmatically waning phase of the limited source in eastern china

late cretaceous palaeomagnetic results from sikhote alin far eastern russia tectonic implications for the eastern margin of the mongolia block summary wepresent palaeomagnetic results from late cretaceous welded tuffs in the kisin group monastirskaya suite primorskaya series collected at 27 sites from the sikhote alin mountain range a high unblocking temperature magnetization component 590 c was isolated after stepwise thermal demagnetization from 25 sites combined with previously reported data reliable characteristic remanence directions from 39 sites are distributed at eight areas ranging from 46 7 n 138 1 e to 43 4 n 134 8 e in the sikhote alin block the bedding tilt test is positive for two area mean directions and inconclusive for the remaining six areas the data set for all 39 sites reveals a positive bedding tilt test at the 99 per cent confidence level and their tilt corrected mean direction is d 335 6 i 54 4 95 8 5 corresponding to a palaeopole at 71 5 n 38 9 e with a95 9 9 this westerly direction is ascertained through the tilt corrected mean direction d 331 1 i 53 5 95 8 5 based on the 25 data selected from four areas kema river terney plastun and moryak rybolov where each data set passes the positive bedding tilt test or reveals an increase in the precision parameter after tilt correction palaeomagnetic declination indicates that the sikhote alin block has rotated counterclockwise by 41 16 with respect to the eurasian continent between late cretaceous times and 53 50 ma compared with palaeomagnetic data from the surrounding regions we find that the rotation recorded in sikhote alin extends westward into the interior of the mongolia block the eastern margin of the asian continent experienced both counterclockwise rotation of the eastern part of the mongolia block and clockwise rotation of the eastern part of the north china block over the cretaceous we interpret these data in terms of a strong net horizontal force towards the ocean side acting on the lithosphere at the eastern margin of the asian continent between the late cretaceous and 53 50 ma intermittently occurring upwellings of mantle and associated horizontal flows may have played an important role in producing the net horizontal force acting on the continental block during late cretaceous times

anabranching rivers ridge form alluvial channels in tropical northern australia sand dominated ridge form anabranching rivers on the kimberley plateau in northwestern australia are a new type of alluvial channel system not previously described or explained in detail this paper examines the morphology sedimentology and stratigraphy of this type of river and proposes mechanisms for their formation and maintenance alternating with relatively narrow bedrock reaches of valley are wider depositional alluvial reaches that support roughly parallel very elongated steep sided and treed sandy ridges of approximately floodplain height these ridges subdivide the total flow system into remarkably straight canal like anabranching channels in this seasonally arid environment there is an abundance of riparian vegetation in places growing chaotically over wider sections of stream bed it is proposed here that the formation of ridges results in a reduction of flow resistance with an increase in depth the ridges concentrate the flow and compensate for the less efficient flow conditions associated with these well vegetated alluvial reaches trees generally do not survive on the bed of the higher energy channels enhanced velocities and increased bed shear act to maintain or increase water and sediment flux in these alluvial reaches the formation of the channels and intervening ridges may be aided by the development of double flow helices in each anabranch similar to that described for much smaller ridge features observed in laboratory flumes anabranches are also observed having formed by channel avulsion scouring new channels into adjacent floodplains particularly in widened sections of valley near tributary junctions

plant material deposition in the tropical burdekin river australia implications for ancient fluvial sediments abstract in the deposits of the burdekin river north queensland australia plant material character and directional fabric together with the sedimentary facies character are generally diagnostic of depositional environment plant material is selectively entrained transported and deposited in all flow conditions ranging from dry season minimal flow

coarse grained floodplain deposits in the seasonal tropics towards a better facies model abstract floodplain deposits in semiarid and subhumid settings with erratic rainfall may contain relatively high proportions of sand because of climatically controlled patterns of discharge and vegetation cover ancient formations with abundant floodplain sands may record fluvial systems with extreme discharge variability of this type but are difficult to interpret because of the paucity of published modern analogues the lower burdekin and haughton river alluvial and delta plains of north queensland australia are used here to illustrate this type of fluvial architecture the modern burdekin and haughton channels have gravelly sand beds and transport a mixed load in the wet season the channels have low relief levees that decrease in amplitude downstream across the low gradient floodplains tropical cyclone activity results in high magnitude short duration sediment charged floods that inundate large areas of the coastal lowland bankfull discharge is infrequently exceeded return interval 25 years because the channels are enlarged by major cyclone induced runoff events and between these events flows are too small to modify the channel form significantly suspended sediment loads and the proportions of these that are sand are particularly high when intense rainfall occurs after prolonged drought when vegetation cover is reduced as a consequence of these factors most of the deposition on the levees and floodbasins occurs in very large discharge events with significant suspended sand load these floods carry a lot of sand out of the channel and efficiently in suspension over the floodplains because of deep inundation boreholes drilled in these floodplains encountered sharply bounded and gradationally bounded sand beds that fine upward or show no vertical grain size trend these are interbedded with thin silt clay and minor gravel beds holocene paleochannels make up about 30 of the floodplain area and consist predominantly of coarse sand that is similar to modern channel bed deposits the overbank sand in contrast is predominantly fine medium grained and beds have distinctly different granulometry from each other and from channel floor deposits efficient sediment partitioning in the runoff and extreme variation in flood magnitude explain variations in sand bed granulometry in the alluvial valley and upper delta plain individual sand beds are difficult to correlate between adjacent boreholes even over very short distances tens of meters in contrast on the lower delta plain overbank sands have a more sheet like geometry this is explained by the lower lying landscape negligible levee development greater inundation depths and reduced surface roughness in addition the channel bodies are thinner and wider and may be connected to overbank sand wings

maximum clear water scour around circular piers the potential predictors of the maximum clear water scour are compared with the available experimental data the range of flow parameters for which these formulas either overpredicted or underpredicted are delineated comparison indicates that the scour formula by laurson and toch is the best predictor among those examined for it encompasses all data and overpredicts less than the other formulas however the laursen and toch formula predicts that the scour depth is independent of sediment size a new formula for the maximum clear water scour is proposed it is very similar to that of laursen and touch but includes the effect of sediment size on scour depth

fluvial islands first stage of development from nonmigrating forced bars and woody vegetation interactions abstract fluvial islands can develop from the channel bed by interactions between pioneer trees and bars although vegetation recruitment and survival is possible on all bar types it is easier for trees to survive on nonmigrating bars developed from a change in channel geometry or to the presence of a steady perturbation this field study details the first stages of development of a vegetated mid channel nonmigrating or forced bar and its evolution toward an island form over six years analysis of bed topographical changes vegetation density and roughness scour and fill depths sediment grain size and architecture and excess bed shear stress highlighted a specific signature of trees on topography and grain size segregation two depositional processes combining the formation of obstacle marks and upstream shifting deposition of sediments led to the vertical accretion of the vegetated bar during the first stage of the bar accretion bedload sediment supply coming from surrounding channels during floods was identified as a key process modulated by the presence of woody vegetation and a deflection effect induced by the preexisting topography grain size segregation between vegetated and bare areas was also highlighted and interpreted as an important process affecting the development of surrounding channels and the degree of disconnection and hence the speed of development of a growing island the heterogeneity of bedload supply can explain why sediment deposition and density of trees are not strictly related a general conceptual model detailing the first stages of evolution from a bar to an established island is proposed for relatively large lowland rivers

gravel antidunes in the tropical burdekin river queensland australia the geological record is punctuated by the deposits of extreme event phenomena the identification and interpretation of which are hindered by a lack of data on contemporary examples it is impossible to directly observe sedimentary bedforms and grain fabrics forming under natural particle transporting high velocity currents and therefore their characteristics are poorly documented the deposits of such flows are exposed however in the dry bed of the burdekin river queensland australia following tropical cyclone induced floods long wave length up to 19 m gravel antidunes develop during short days high discharge flows in the upper burdekin river maximum recorded discharge near the study reach over 25 600 m s in february 1927 flood water levels fall quickly metres in a day and flow is diverted away from raised areas of the river bed into subchannels exposing many of the high stage bedforms with little reworking by falling stage currents gravel bedforms were observed on the dry river bed after the moderate flows of february 1994 max 7700 m s and january 1996 max 3200 m s the bedforms had wave lengths in the range 8 19 m amplitudes of up to 1 m with steeper stoss than lee faces and crest lines generally transverse to local peak discharge flow direction the gravel fabric and size sorting change systematically up the stoss and down the lee faces the antidune deposits form erosive based lenses of sandy gravel with low angle downstream dipping lamination and generally steep upstream dipping a b planes the internal form and fabric of the antidune gravel lenses are distinctly different from those of dune lee gravel lenses the erosive based lenses of low angle cross bedded gravel with steep upstream dipping a b planes are relatively easy to recognize and may be diagnostic of downstream migrating antidunes the antidune gravel lenses are associated with thick to 1 m high angle cross bed sets ancient antidune gravel lenses may be diagnostic of episodic high discharge conditions and particularly when they are associated with high angle cross bedded gravelly sand they may be useful for palaeoenvironmental interpretation

a kinematic model for surface irrigation verification by experimental data a kinematic model for surface irrigation is verified by experimental data obtained for 31 borders these borders are of varied characteristics calculated values of advance times water surface profiles when water reaches the end of the border and recession times are compared with their observations the prediction error in most cases remains below 20 for the advance time and below 15 for the recession time the water surface profiles computed by the model agree with observed profiles reasonably well for the data analyzed here the kinematic wave model is found to be sufficiently accurate for modeling the entire irrigation cycle except for the vertical recession

kinematic shock sensitivity analysis a series of numerical experiments is performed to determine the flow and channel characteristics that are most conducive to kinematic wave steepening and associated kinematic shock phenomena relevant flow and channel characteristics are identified at the outset and a program of 80 computer runs is completed varying the inflow hydrograph peak froude number time to peak and base to peak flow ratio and the channel cross sectional shape it is found that all have a definite effect on kinematic shock development the size of the wave is perhaps mostly responsible for the occurrence or nonoccurrence of the shock

sedimentology of the upper burdekin river of north queensland australia an example of a tropical variable discharge river the burdekin river is an example of a class of tropical streams which experience two to four orders of magnitude variation in discharge in response to seasonal but erratic monsoonal rainfall floods of the burdekin rise abruptly reaching peak discharges of up to 40 000 m s in less than 24 h maintain peak flow for up to a few days and recede exponentially the geomorphology and deposits of these rivers reflect the extreme discharge fluctuations and have not previously been described a stretch of the upper burdekin river comprising four bends and one straight reach was examined near the town of charters towers the river bed is largely exposed for most of any year with a small misfit perennial channel carrying low stage flow major geomorphic elements of bends include point bars with ridge and swale topography three distinct types of chute channels avalanche slipfaces up to 5 m or more high around the downstream edges of bars and on the outer part of one point bar an elevated vegetated ridge straight reaches are flat or gently inclined sand and gravel covered surfaces much of the river bed is covered by well sorted in places gravelly coarse to very coarse grained sand with local accumulations of pebble to boulder gravel lower parts of the river bed are periodically draped by mud which is desiccated on exposure dunes and plane beds are the most commonly occurring bedforms with local development of gravelly antidunes most bank tops and upper vegetated bars are covered by silt and fine grained sand the river bed also hosts a low diversity but locally high abundance flood tolerant flora dominated by the paperbark tree melaleuca argentea which plays an important role in controlling the distribution of sediment the gross geomorphology of the river bed and most of the sedimentary features are interpreted as having formed during major bankfull or near bankfull flows which have a recurrence of about 18 years based on 65 years hydrographic data the initial rapid drop in discharge following flood peaks appears to preserve flood peak features on upper bars more or less intact whereas lower areas are subjected to variable degrees of modification during falling stage and by more frequent non bankfull discharge events

avoiding confusion between pressure front pulse displacement and groundwater displacement illustration with the pumping test in a confined aquifer two distinct phenomena may be distinguished and defined during a pumping test conducted in a confined aquifer the pressure front pulse displacement and the groundwater displacement this scientific briefing examines and clarifies the difference between the pressure wave displacement and the groundwater displacement by stating the differences in their respective transit times and velocities the pressure front pulse displacement is controlled by the diffusivity of the aquifer whereas groundwater displacement is controlled by the pumping flow rate and the effective porosity of the aquifer to calculate the transit time and velocity of each type of displacement several equations are presented and compared an example is provided to illustrate the differences in velocity between the pressure front pulse displacement and the groundwater displacement

in channel woody vegetation controls on sedimentary processes and the sedimentary record within alluvial environments a modern example of an anabranch of the river loire france a multidisciplinary approach was used to analyse the role of pioneer trees populus nigra on bar formation in the modern fluvial system of the river loire france data were collected on seven plots located on a secondary channel chosen for their vegetation cover and their sedimentary context physical features of vegetation topographical evolution sediment grain size and flow velocity were investigated during and after floods between 2001 and 2003 woody vegetation responds morphologically to fast flowing waters and sediment deposition these adaptations influence the role played by trees on local sedimentary processes some morphological types of trees exert a strong influence during flood events by deflecting reducing or increasing the flow energy as a consequence the evolution of bedforms distribution of sediment grain size and slopes are controlled by the flood type the morphological context i e high or low energy zones the morphology of the vegetated bar and the characteristics of vegetation conceptual models are proposed to account for local processes and evolution of tree groves the first model which describes the behaviour of groves during a single flood underlines the sediment deposition downstream of the trees and the trapping of bedload sediments during the falling stage of the flood the reorientation of current streams constrained by both local bed topography and woody vegetation induces transverse sediment fluxes for these water levels the control exerted by trees on small scale sedimentary processes becomes significant the second model shows the evolution of vegetation bands over several flood events in particular it describes the influence of vegetation on the fixing and reworking of bedload sediments during the falling limb of the hydrograph the coalescence of vegetation induced bedforms and the resulting morphological changes increase the deflection power of the vegetated bar inducing the deposition of finer sediments

kinematic wave modelling of vertical movement of snowmelt water through a snowpack vertical movement of snowmelt water through snowpacks is modelled by applying the kinematic wave theory analytical solutions are obtained for moisture flux particle velocity time history and velocity of meltwater front and total moisture content for a single melt event assuming that the melt rate is constant these solutions are extended to the case involving more than one event

kinematic wave solutions for dam break floods in non uniform valleys abstract in non uniform valleys dam break flood waves can be significantly affected by downstream variations in river width slope and roughness to model these effects we derive new analytical solutions to the kinematic wave equation applicable to rating curves in the power law form and hydrographs of generic shape as long as they produce a single shock at the wave front new results are first obtained for uniform channels using the gauss green theorem applied to characteristic bounded regions of the x t plane the results are then extended to non uniform valleys using a change of variable that homogenizes river properties by rescaling the distance coordinate the solutions are illustrated and validated for idealized cases then applied to three historical dam failures the 2008 breaching failure of the tangjiashan landslide dam the 1976 piping failure of teton dam and the 1959 sudden failure of malpasset dam in spite of the much reduced computational cost and data requirements the results agree well with the field data and with more elaborate simulations they also clarify how both river and hydrograph properties affect flood propagation and attenuation

multiple magma sources involved in marginal sea formation pb sr and nd isotopic evidence from the japan sea region the cenozoic basaltic rocks in sikhote alin and sakhalin exhibit a change over 55 m y from subduction zone related to continental rift related volcanism as the japan sea opened between eastern sikhote alin and the japan arc the temporal geochemical trends in volcanic rocks erupted before and during the opening of the japan sea suggesting that there was a change in magma source from the lithosphere to the depleted asthenosphere as the japan sea opening progressed two geochemical groups can be identified within the basalts that postdate the japan sea opening tholeiitic basalts and alkalic basalts as the tholeiitic basalts have emi type signatures we propose that the tholeiites had a significant contribution from an emi type precambrian subcontinental lithospheric mantle the alkalic basalts yielding geochemical characteristics similar to enriched oceanic island basalts may have been derived from the subcontinental asthenospheric mantle the opening of the japan sea was triggered by lateral migration of asthenospheric mantle from beneath northeast china toward the japan arc

hydraulic control on the development of megaflood runup deposits abstract runup deposits are veneers of alluvium that drape floodway valley side walls above the height of giant bars deposited during megafloods given sufficient sediment supply the highest giant bars deposited in re entrants along the flood margins tend to grow to close to the maximum time averaged water level of the flood however considerable fluctuations in the water level caused by sediment charged floodwaters surging over shorter time scales are responsible for the higher runup deposits here the theoretical calculations of the expected maximum runup heights are compared with surveyed heights of six runup deposits in the chuja valley altai siberia the limitations and strengths of the theoretical approach are identified and modified parameters proposed that can be used to provide partial explanation for the differences between theory and observation conceptually surging can be viewed as caused by four interrelated elements 1 propagation of undular weir flow 2 macroturbulence 3 flow separation and 4 standing reflection and interference waves the heights of the observed runup deposits primarily are related to the depth of the flood water above the bar tops and to a lesser extent the froude number but tend to lie below the maximum surge heights of the modelled flow changes in the effective geometry of the flow re entrant mediating flow patterns as water depth increases is likely the cause of mismatch between theory and observation runup deposits may also lie at lower elevations than predicted because of sediment supply considerations and the return flow of surges combing down deposits nonetheless the difference between observed and predicted runup heights is often only a few tens of metres such that for deep floods runup deposits potentially are useful palaeostage indicators the analysis also indicates that upper stage plane beds do not dominate bar tops rather bar top deposition was primarily to lower stage plane beds from dense suspensions

revisiting the dynamics of catastrophic late pleistocene glacial lake drainage altai mountains central asia abstract in this work we present a whole system model of megafloods from catastrophic ice dam failure in the late pleistocene that comprises the study of the dynamics of the glacial lake the propagation of the flood wave downstream of the dam and an approximation to the ice breach process the ice dam incision rate was simply considered an unknown constant which was varied systematically to best fit the maximum altitude of the simulated water surface and the paleostage indicators in the downstream valley during the transient megaflood hence the hydrograph resulting from the breach of the ice dam was not prescribed but was an output of the paleohydraulic reconstruction by considering two possible configurations of the breach in the ice dam i e full or partial removal of the ice we constrained the incision rate in the narrow range of 28 42 m h 1 two connected glacial lakes kuray and chuja released 95 of the stored water volume i e 564 km3 in 33 8 hours a peak discharge of 10 5 m m3 s 1 was required to form numerous giant bars and run up deposits in the chuja and katun valleys the peak streamflow occurred after 11 h when 45 of the available lake volume had been evacuated from the kuray and chuja basins further verification of the reconstructed megaflood was achieved by studying the computed hydraulic conditions during the lake draining that justify the existence and orientation of several fields of subaqueous gravel dunes in the glacial lake complex spatiotemporal patterns during the recession stage of the flood built most of the fields of bedforms in terms of nondimensional parameters the froude and shields numbers that formed the dune fields were similar to those observed in large sandy rivers but the flow was undoubtedly unsteady and two dimensional we conclude by noting that the extensions of the simulated area cannot be cropped or analysed by independent parts in order to predict the formation of the most relevant geological records due to the unsteady two dimensional nature of the flow motion and the development of backwater effects in the drainage network lastly the paleohydrological reconstruction of a megaflood has helped not only to infer the dynamics of the event but also to retrodict the mean parameters of the ice dam failure mechanism

controls of groundwater floodwave propagation in a gravelly floodplain summary interactions between surface water and groundwater can occur over a wide range of spatial and temporal scales within a high hydraulic conductivity gravelly floodplain in this research dynamics of river groundwater interactions in the floodplain of the matane river eastern canada are described on a flood event basis eleven piezometers equipped with pressure sensors were installed to monitor river stage and groundwater levels at a 15 min interval during the summer and fall of 2011 results suggest that the alluvial aquifer of the matane valley is hydraulically connected and primarily controlled by river stage fluctuations flood duration and magnitude the largest flood event recorded affected local groundwater flow orientation by generating an inversion of the hydraulic gradient for 16 h piezometric data show the propagation of a well defined groundwater floodwave for every flood recorded as well as for discharges below bankfull 0 5 qbf a wave propagated through the entire floodplain 250 m for each measured flood while its amplitude and velocity were highly dependent on hydroclimatic conditions the groundwater floodwave which is interpreted as a dynamic wave propagated through the floodplain at 2 3 orders of magnitude faster than groundwater flux velocities it was found that groundwater exfiltration can occur in areas distant from the channel even at stream discharges that are well below bankfull this study supports the idea that a river flood has a much larger effect in time and space than what is occurring within the channel

unsteady sedimentation in nonuniform rills abstract runoff and sediment were measured from agricultural land exposed to controlled simulated rainfall we extended the kinematic unsteady overland sedimentation theory of prismatic channels to the experiments by considering both hydraulics and sediment dynamics of rill flow for changing flow geometries of nonuniform and unsteady rill development the characteristic unimodal concentration peak observed in the experiments and the changing channel geometry were interpreted in theoretical terms overland sedimentation in unsteady nonprismatic rills under uniform rainfall can be described with kinematic models of flow entrainment and deposition applied to developing flow geometries this is not possible with sheet flow models other interpretations are considered and experimental needs are identified

flow and sediment dynamics in the vegetated secondary channels of an anabranching river the loire river france this study investigates the hydrological and sedimentological mechanisms occurring in the vegetated secondary channels of an anabranching river affected by incision the loire river france during and after flood events that occurred between 2000 and 2003 observations and measurements were performed on a vegetated secondary channel located in the study site of brehemont 790 km downstream the source morphological changes and sediment dynamics were analysed using low elevation airborne photographs topographic and bathymetric surveys and scour chains the hydraulic behaviour of the channel was also analysed by measurements performed on flow velocity and direction during different flood stages in order to quantify the influence of woody vegetation on flow resistance the roughness of bands of trees was determined from measurements performed on the field the impact of the disruption of armour layers on bedload pulses the variation of sedimentary processes during a single flood event and the fixation of bedforms by vegetation are all identified as key processes influencing the behaviour of the study channel topographic surveys demonstrate that sediment dynamics is substantial in the upstream part of the channel and that sediment budgets are different according to the temporal scale considered moreover an asymmetrical behaviour of the secondary channel is demonstrated reduced quantities of sediment deposited and preserved in the vegetated zones contrast with material by passing observed in the third order channels flow velocity and direction measurements indicate that these parameters vary according to the water level and to the morphological units of the channel pools riffles vegetated areas during low flows scouring and export of particles from the secondary channel are a consequence of reduced sediment supply from the main channel of the loire river for these water levels sedimentation occurs in pools where velocity and turbulence decrease whereas third order channels are subjected to erosion during high discharges large quantities of sediment available in the main channel feed the temporary stores formed by riffles and bars in the secondary channel the vegetated area located in the downstream part of the secondary channel deflects current trickles at low discharges and decreases flow velocity during high water levels the sedimentary accretion observed in this area exerts a feedback on flow and sedimentary processes d 2005 elsevier b v all rights reserved

preservation of in situ arborescent vegetation and fluvial bar construction in the burdekin river of north queensland australia abstract in sub humid parts of north queensland ne australia certain types of trees are well adapted to living in river bed habitats the bed of the tropical variable discharge upper burdekin river hosts a community dominated by the paperbark melaleuca argentea trees grow preferentially in flow parallel linear groves and engineer their own environment by deflecting currents building sand and gravel bars and stabising banks this is the first study to document in channel bar development resulting from vegetation growth rather than the reverse which has been inferred by previous workers in the burdekin river study site individual melaleuca range from seedlings to mature trees over 100 years old these trees survive regular partial to total submergence and impact damage during wet season runoff events often reaching over 20 000 m3 s 1 at peak discharge partly by adopting structural and growth modifications these modifications include a reclined downstream trailing habit multiple stemmed form modified crown with weeping foliage development of thick spongy bark root regeneration and group strategies notably development of flow parallel linear groves following death in situ remains of trees are preserved within the mainly coarse sand to gravel channel fill either as reclined stems trunks stripped of branches and foliage or as more upright trunks snapped at a height of typically 1 2 m above base both with roots the morphological adapations and styles of preservations of in situ vegetation within the burdekin river are considered distinctive of variable discharge rivers and may be useful in the identification of facies formed in such environments in the rock record particularly when associated with bar development

analytical solutions for gradual dam breaching and downstream river flooding 1 an analytical model is proposed to describe lake drainage and downstream flooding due to the gradual breaching of natural and manmade earthen dams erodible triangular dams are considered undergoing gradual incision by a breaching channel of constant effective width adopting a simple stream power law for dam material transport the long profile evolution of the breaching channel is governed by a diffusion equation with variable diffusion rate proportional to the water discharge the resulting flood is routed downstream using the kinematic wave equation moving boundary problems are obtained due to retrogression of the breach crest and to the downstream propagation of the flood wavefront for both the dam breaching and flood routing problems explicit analytical solutions are derived they depict a breaching process that is at first self accelerating then becomes self limiting results include boundary paths long profiles and stage and discharge hydrographs in particular the breaching solution yields a discharge hydrograph of simple analytical shape that turns out to be ideally suited for kinematic wave routing the model is applied to the well documented breaching of the tangjiashan landslide dam sichuan in june 2008 calculated results for this and other cases are in reasonably good agreement with the measured data as the model is simple to apply with minimal computational and data requirements it could prove useful as a tool for rapid risk assessment the proposed analytical approach also complements numerical models by providing more transparent links between solution outcomes and the problem data

cenozoic rifting and volcanism in eastern china a mantle dynamic link to the indo asian collision abstract the indo asian continental collision is known to have had a great impact on crustal deformation in south central asia but its effects on the sublithospheric mantle remain uncertain studies of seismic anisotropy and volcanism have suggested that the collision may have driven significant lateral mantle flow under the asian continent similar to the observed lateral extrusion of asian crustal blocks here we present supporting evidence from p wave travel time seismic tomography and numerical modeling the tomography shows continuous low velocity asthenospheric mantle structures extending from the tibetan plateau to eastern china consistent with the notion of a collision driven lateral mantle extrusion numerical simulations suggest that at the presence of a low viscosity asthenosphere continued mass injection under the indo asian collision zone over the past 50 my could have driven significant lateral extrusion of the asthenospheric mantle leading to diffuse asthenospheric upwelling rifting and widespread cenozoic volcanism in eastern china

unit bar architecture in a highly variable fluvial discharge regime examples from the burdekin river australia unit bars are relatively large bedforms that develop in rivers over a wide range of climatic regimes unit bars formed within the highly variable discharge burdekin river in queensland australia were examined over three field campaigns between 2015 and 2017 these bars had complex internal structures dominated by co sets of cross stratified and planar stratified sets the cross stratified sets tended to down climb the development of complex internal structures was primarily a result of three processes i superimposed bedforms reworking the unit bar avalanche face ii variable discharge triggering reactivation surfaces and iii changes in bar growth direction induced by stage change internal structures varied along the length and across the width of unit bars for the former down climbing cross stratified sets tended to pass into single planar cross stratified deposits at the downstream end of emergent bars such variation related to changes in fluvial conditions whilst bars were active a hierarchy of six categories of fluvial unsteadiness is proposed with these discussed in relation to their effects on unit bar and dune internal structure across deposit variation was caused by changes in superimposed bedform and bar character along bar crests such changes related to the three dimensionality of the channel and bar geometry when bars were active variation in internal structure is likely to be more pronounced in unit bar deposits than in smaller bedform for example dune deposits formed in the same river this is because smaller bedforms are more easily washed out or modified by changing discharge conditions and their smaller dimensions restrict the variation in flow conditions that occur over their width in regimes where unit bar deposits are well preserved their architectural variability is a potential aid to their identification this complex architecture also allows greater resolution in interpreting the conditions before and during bar initiation and development