new absolute time scale for the quaternary climate in the chinese loess region by grain size analysis continuous loess sequences in china provide not only information for paleoclimatic reconstructions but also permit the establishment of a reliable absolute time scale for the quaternary an empirical relationship is developed between the grain size of the loess and the sedimentation rate in a short well dated reference section step 1 this relationship is extrapolated to the complete quaternary section step 2 after derivation of the sedimentation rate by measuring the grain size in all the layers of the sequence the duration of deposition of each layer is obtained by dividing thickness by sedimentation rate and subsequently the age of each point in the sequence is calculated by adding together all the duration values of the overlying layers the chronology of the extrapolated part of the section obtained in this way is independent of dates provided by other methods and may also be checked by them

subsurface lateral flow generation in aspen and conifer dominated hillslopes of a first order catchment in northern utah mountain headwater catchments in the semi arid intermountain west are important sources of surface water because these high elevations receive more precipitation than neighboring lowlands this study examined subsurface runoff in two hillslopes one aspen dominated the other conifer dominated adjacent to a first order stream in snow driven northern utah snow accumulation soil moisture trenchflow and streamflow were examined in hillslopes and their adjacent stream snow water equivalents swes were greater under aspen stands compared to conifer the difference increasing with higher annual precipitation semi variograms of shallow spatial soil moisture patterns and transects of continuous soil moisture showed no increase in soil moisture downslope suggesting the absence of subsurface flow in shallow 12 cm soil layers of either vegetation type however a clear threshold relationship between soil moisture and streamflow indicated hillslope stream connectivity deeper within the soil profile subsurface flow was detected at 50 cm depth which was sustained for longer in the conifer hillslope soil profiles under the two vegetation types varied with deep aspen soils having greater water storage capacity than shallow rocky conifer soils though swes were less under the conifers the soil profile had less water storage capacity and produced more subsurface lateral flow during the spring snowmelt copyright 2010 john wiley sons ltd

the effect of macropores on bi directional hydrologic exchange between a stream channel and riparian groundwater summary macropores and soil pipes in stream banks are common geomorphic features macropores and soil pipes that are open to the channel i e bank face connected macropores are inundated when channel stage is elevated e g from precipitation snowmelt dam release however previous studies have not investigated macropore impact on bi directional water exchange between the channel and bank riparian groundwater under variable hydrologic conditions we monitored two transects of riparian groundwater wells perpendicular to the bank of a 2nd order stream for a year one with bank face connected macropores m transect and one without bank face connected macropores nm transect fluctuations in water level and temperature during storms in those wells closest to the channel were on average 139 and 29 higher respectively in the presence of macropores rising head tests in the same wells indicated that hydraulic conductivity was 61 140 times higher in the presence of macropores bank storage indicated by gradient reversals between channel and riparian zone occurred on two temporal scales bank storage during storms was more frequent in the m transect occurred all year than in the nm transect occurred just in winter and spring smaller magnitude gradient reversals at the m transect are consistent with faster head equilibration and greater exchange volume bank storage also occurred on an annual basis with channel water entering storage during summer and fall and returning to the channel during winter and spring taken together these results suggest that macropores act as preferential flow paths that enhance the connectivity between channels and riparian groundwater that influences bank storage where bank macropores are present conceptual models of hyporheic and groundwater flow should account for their effects

field experiments in a fractured clay till 2 solute and colloid transport a field tracer experiment was conducted in a lateral flow field in the weathered and highly fractured upper 6 m of a 40 m thick clay rich till plain in southwestern ontario in the upper 3 m where fractures are closely spaced 5 m d simulations with a discrete fracture porous matrix flow and transport model which used the cubic law for flow in fractures showed that diffusion of the solutes but not the much larger colloids into the matrix pore water between fractures is sufficient to cause the observed difference in solute and colloid transport rates transport derived and hydraulic conductivity derived fracture aperture values were similar within a factor of 3 and falling mainly within a range of 5 40 m in the upper 3 m the solute tracers were evenly distributed between pore water in the fractures and the matrix and as a result solute transport can be closely approximated with an equivalent porous medium epm approach below this depth fractures are more widely spaced 0 13 to 1 m with concentration peaks tending to occur near visible fractures and solute transport cannot be adequately described with an epm approach

four dimensional assimilation in the presence of baroclinic instability current operational assimilation methods have revealed deficiencies in cases of strong baroclinic development baroclinic conditions are therefore appropriate for evaluating the potential for improvement which could be achieved through the implementation of a fully four dimensional data assimilation in this paper the behaviour of a variational scheme is investigated for a typical baroclinic instability problem where a wave develops and retroacts on to the basic zonal flow

flow and solute transport through the soil matrix and macropores of a hillslope segment subsurface flow from various portions of a soil profile on a steep forested hillslope was evaluated by two sets of step change miscible displacement tests at different application rates and antecedent hydrologic conditions solutions of nacl 1000 mg l 1 cl were applied at steady state rates equivalent to 20 and 30 mm h 1 of standing water over the entire plot area using a line irrigation source located 1 5 m upslope lateral distance from an excavated soil pit subsurface flow and tracer breakthrough from five portions the organic rich soil layer including macropores the mineral soil matrix and three groups of macropores in the mineral soil layer of the soil profile were individually measured and analyzed using a convective dispersive model matrix flow dominated discharge from the soil pit during tracer tests 70 93 of total discharge however during wet periods with upslope drainage macropores including organic rich soil contributed proportionally more flow than during periods when upslope drainage was minimal outflow from macropores during the test with wet antecedent conditions had lower cl concentrations than drainage from the soil matrix suggesting dilution in macropores from upslope drainage effective pore volumes calculated for the flow averaged breakthrough data from the entire profile were much less 40 than the estimates measured by tensiometers of total volume of pore water suggesting that preferential flow significantly contributed to subsurface transport of tracer the pore volume for the entire profile increased only slightly with increasing application rate however the relative proportions of pore volumes calculated for individual portions varied proportionally to antecedent hydrologic conditions these changes are attributed to the expansion of individual macropores with surrounding soil and the lateral extension of macropore networks during wetter conditions

effect of catchment scale subsurface mixing on stream isotopic response a 3 8 ha watershed on the west coast of new zealand was instrumented with suction lysimeters and automatic water samplers to determine the relationship between subsurface isotopic and chemical concentrations to those of rainfall and resulting streamflow a t test showed that 2 represented a significant difference between successive sample deuterium values eleven rainfall episodes were subdivided into two categories 1 two events where stream isotopic composition did not deflect 2 from prestorm values and 2 four events which demonstrated new water flushing detailed analysis of one 47 mm rainfall 9 8 mm runoff event showed that old water dominated stream water exiting the watershed by 90 using a standard two component hydrograph separation for deuterium corroborated by cl and electrical conductivity three component hydrograph separation indicated that 12 16 was in the form of soil water with 5 as on channel precipitation and 80 groundwater analysis of over 1000 water samples revealed systematic trends in soil water and groundwater isotopic composition both in a downslope and downprofile direction between storm suction lysimeter deuterium data showed a systematic dampened response to temporally variable rainfall deuterium concentrations multivariate cluster analysis revealed three distinct soil water groundwater groupings with respect to soil depth and geographic position within the watershed within storm suction lysimeter sampling preserved similar groupings indicating that the subsurface reservoir is poorly mixed on short time scales understanding subsurface mixing response to rainfall should greatly improve models of episodic stream response and partitioning of storm flow into waters of different age

impact of piping on gully development in mid altitude mountains under a temperate climate a dendrogeomorphological approach abstract gullies are complex geomorphic systems induced and transformed not only by surface erosion processes but also by subsurface processes such as piping however the transient nature of piping makes this process more difficult to observe and study especially when a pipe roof has totally collapsed this study aims at assessing piping impact on gully initiation and development using dendrogeomorphological analyses which are a novel approach in piping study the survey was carried out in a mountainous area under a temperate climate using the bere nica wyzna catchment in the bieszczady mts eastern carpathians as a case study we estimated the minimum age of pipe collapses and presented the transformation of pipe collapses in order to identify the direction of pipe and gully development we also verified the contribution of piping to gully development by the reconstruction of gully bottom deepening the analysis was based on changes in tree and root wood anatomy in diffuse porous deciduous angiosperm species i e common alder alnus glutinosa and field maple acer campestre the pipe collapses in the piping system studied are at least 19 to 23 27 years old and the pipe roof initially collapsed in the lower sections of the slope above the gully head and the pipe develops up the slope by headward erosion the gully that was analysed in forest had been deepened by piping during several episodes connected with high precipitation events in contrast the pipe located in grasslands collapsed 1 2 years after such events indicating that dense vegetation delays pipe collapse this study shows that dendrogeomorphological analyses based on diffuse porous deciduous angiosperm species may be a useful tool in piping research it provides information on pipe and gully development as well as enabling estimates to be made of the age of pipe collapses

soil pipe distribution and hydrological functioning within the humid tropics a synthesis some of the most responsive runoff systems in the world are found within the humid tropics these runoff responses are likely to be affected by the presence of natural pipes within the soil this study provides a synthesis of the hydrological aspects of these phenomena within the humid tropics of the studies reporting the presence of soil piping within the humid tropics most are associated with ultisol soils and locally most pipe outlets are observed on the lower sections of hillslopes while the drainage role of pipes has been observed providing faster and slower components of stream hydrographs the mechanism of their recharge remains less clear in part this is because their spatial extent is poorly mapped within the hillslopes of the humid tropics further studies quantifying the length and recharge of soil pipe networks within the humid tropics are needed

chernobyl fallout and radionuclide activity in bottom sediments at the river adige estuary northern adriatic sea italy the artificial radionuclides 137cs 134cs and 106ru have been determined up to 16 cm deep in two sediment cores collected in march 1988 at the river adige estuary in the northern adriatic sea interdependent relations between the properties of the sediment levels and the activity of radionuclides have been investigated using multivariate statistical analysis the interactions between radiocontaminants and the particulate matter or water phase are discussed during their transfer processes from the river to the estuary and the marine environment diffusion phenomena within the sedimentary column have also been considered the vertical distribution of the artificial radionuclides due to chemobyl fallout in sediment cores from the river adige mouth compared to those from similar estuarine environments in the adriatic sea point out a general rapid accumulation of river borne solid material in coastal zones of the north adriatic sea

snowmelt runoff pathways in a boreal forest hillslope the role of pipe throughflow abstract on an instrumented slope of the lac laflamme basin we observed that during snowmelt season 1 the unsaturated matrix flow seems to be a negligible component of the downslope flow through the soil horizons 2 the groundwater flow from an aquifer in till a few meters thick is the major pathway for rain melt inputs and 3 when groundwater levels are high a turbulent pipe throughflow occurs at the mineral and organic soils interface gauging one of the subsurface streams showed that although its discharge is correlated and synchronized with nearby groundwater levels its hydrograph often reflected that of rain melt input according to our calculations pipe throughflow does not carry more than one fifth of the seasonal rain melt input during short periods hourly basis however it may become the main source of water input to the lake the water delivered by pipe throughflow forms a distinct 0 5 1 m thick acidic layer ph 4 4 4 8 that invades the lake just beneath the lake ice cover and is susceptible to affect the fish spawning ground

chemical fingerprints of hydrological compartments and flow paths at la cuenca western amazonia a forested first order catchment in western amazonia was monitored for 2 years to determine the chemical fingerprints of precipitation throughfall overland flow pipe flow soil water groundwater and streamflow we used five tracers hydrogen calcium magnesium potassium and silica to distinguish fast flow paths mainly influenced by the biological subsystem from slow flow paths in the geochemical subsystem the former comprise throughfall overland flow and pipe flow and are characterized by a high potassium silica ratio the latter are represented by soil water and groundwater which have a low potassium silica ratio soil water and groundwater differ with respect to calcium and magnesium the groundwater controlled streamflow chemistry is strongly modified by contributions from fast flow paths during precipitation events the high potassium silica ratio of these flow paths suggests that the storm flow response at la cuenca is dominated by event water

directions of preferential flow in a hillslope soil 1 quasi steady flow preferred infiltration is mainly perceived as vertically down whereas subsurface storm flow is thought to occur parallel to slopes the transition from vertical to lateral flow in a layered hillslope soil is the focus of the contribution transient flow is assumed to move as a wetting front three time domain reflectometry tdr wave guides each 0 15 m long were mounted in the shape of a truncated tetrahedron with its peak pointing down each wave guide focuses the front velocity along its axis the three front velocity vectors are decomposed into their x y and z components which are then assembled to the resultant velocity vector the volume density flux of preferred flow is the product of the front velocity and the mobile water content the latter is the amplitude of transient soil moisture measured with each wave guide the resultant vector of the volume flux density is computed similarly to the velocity vector the experimental approach allows for the rapid assessment of transient flows without relying on the variation of water potentials the experiments indicate that the directions of the resultant vectors of velocity and volume flux density can be estimated if the moisture variations of the three tdr wave guides are strongly correlated during the passing of the wetting front

characteristics of wave packets in the upper troposphere part i northern hemisphere winter abstract gridded data produced by the ecmwf reanalysis project have been analyzed to document the properties of wave packets in the northern hemisphere winter midlatitude upper troposphere based on results from earlier investigations 300 hpa meridional wind variations were chosen for analysis wave packet envelopes were also defined by performing complex demodulation on the wind data the properties of the wave packets are mainly illustrated using time lagged one point correlation maps performed both on and wave packet envelopes the results show that over most regions in the northern hemisphere winter with the exception of the deep tropics and near the aleutian low medium scale waves dominant wavenumber 5 8 exhibit the characteristics of downstream development and occur within wave trains that propagate with eastward group velocities much faster than the phase speeds of individual phases of the waves their group velocity is highly correlated with the local time mean 200 400 hpa wind while the

shallow groundwater response to rainfall on a forested headwater catchment in northern coastal california implications of topography rainfall and throughfall intensities on peak pressure head generation the pore water pressure head that builds in the soil during storms is a critical factor for the prediction of potential slope instability we report findings from a 3 year study of pressure head in 83 piezometers distributed within a 13 ha forested catchment on the northern coast of california the study s primary objective was to observe the seasonal and storm based dynamics of pressure head at a catchment scale in relation to observed rainfall characteristics and in situ topography to better understand landscape patterns of pressure head an additional goal was to determine the influence of the interaction between rainfall and forest canopy in altering delivery of water and pressure head during the large storms necessary to induce landsliding we found that pressure head was highly variable in space and time at the catchment scale pore pressures peaked close to maximum rainfall intensity during the largest storms measured the difference between rainfall and throughfall delivered through the canopy was negligible during the critical landslide producing peak rainfall periods pore pressure was spatially variable within the catchment and did not strongly correlate with surficial topographic features only 23 of the piezometers located in a variety of slope positions were found to be highly responsive to rainfall topographic index statistically explained peak pressure head at responsive locations during common storms but not during the larger storms with potential to produce landslides drainage efficiency throughout the catchment increased significantly in storms exceeding 2 to 7 months peak pressure head return period indicated by slowing or cessation of the rate of increase of pressure head with increasing storm magnitude this asymptotic piezometric pattern persisted through the largest storm measured during the study faster soil drainage suppressed pressure head response in larger storms with important process implications for pore pressure development and landslide hazard modelling copyright 2012 john wiley sons ltd

structure and evolution of baroclinic waves as inferred from regression analysis abstract the structure of transient disturbances with periods shorter than a week is documented an the basis of one point regression maps and longitude height sections derived from the national meteorological center nmc operational analyses for nine winter seasons the reference time series for the regression coefficients is highpass filtered normalized 500 mb height at a grid point in the pacific stormtrack the field variables that were regreesed on the reference time series were not filtered the regression statistics yield quantitative estimates of the amplitudes of the high frequency fluctuations in the geopotential height temperature wind ageostrophic wind vorticity divergence vertical velocity and outgoing longwave radiation fields the observed high frequency fluctuations exhibit a vertical and meridional structure suggestive of baroclinic waves evolving through the mature phase of their life cycle most of the results are in qualitative agreement with previous studies but the ageostrop

runoff generation processes estimated from hydrological observations on a steep forested hillslope with a thin soil layer abstract in order to understand runoff generation processes on a forested hillslope involving large heterogeneities this study monitored runoff from a steep hillslope with a thin soil layer as well as matric potential within it and analyzed their responses to storm rainfall a comparison of storm runoff responses from the study slope with those from two adjacent catchments one of which includes it showed that physical properties of the slope reflected the runoff characteristics although no responses occurred in very dry conditions because of the absence of wet zones near the stream the area contributing to storm runoff more rapidly extended to the whole slope due to its topographic properties they also caused its steep hydrographs produced in the wettest condition where almost all the rainfall contributed to storm runoff in this wettest condition tensiometric responses near bedrock showed the vertical quick propagation of the rainfall pulse and a good agreement of storm hydrograph simulated through a kinematic wave runoff model suggested that runoff from the slope was produced by a lateral flow on the bedrock receiving the quick propagation in a transition process from dry to the wettest conditions the development of the lateral flow producing smaller responses at the downslope end was estimated from decreasing of matric potential near bedrock from high negative to low values with increasing cumulative rainfall

subsurface flow velocities through selected forest soils south island new zealand subsurface flow through soils in tawhai big bush and craigieburn state forests has been studied by applying water at a line source 1 m upslope from a pit in the base of which an intercepting trough is located by measuring lag times between the centres of mass of input and outflow and between the start of input and start of outflow minimum estimates of mean and maximum flow velocity v and vmax at 51 locations were obtained mean values for the tawhai sites were for v 0 3 cm s and for vmax 0 42 cm s but a considerable degree of variability was present with coefficients of variation up to 90 a number of different pathways through the soil are followed by flowing water macropore networks root channels etc are effective transmitters of water and at some sites conveyed up to 40 of the input rapidly to the interception trough variability in flow velocity and the proportion of the input appearing as rapid outflow is a function of antecedent moisture conditions and of the relative importance of the various pathways at a given site which is in turn a function of the characteristics of the soil the macropore network and the parent material at the base of the soil at sites where the soil had an open structure and the parent material was shattered or permeable the macropore network was a less important control upon soil hydrological behavior than where the subsoil had a less open structure and was underlain by impermeable bedrock measurements of flow velocities on undisturbed logged and logged burned planted sites were made at tawhai sf but the spatial and temporal variability was such that no statistically significant differences could be discerned the time lapse since logging may be insufficient for changes in the root systems to be having a hydrological impact but the high variability would require a sample size of over 1000 to show a significant difference in velocity of even 10 for rapid flow through macropores to have a significant influence on streamflow saturation of the soil is necessary before water can enter the macropores soil topographic geologic and climatic conditions in tawhai sf are such that saturation of the lower layers of the soil regularly occurs so that rapid flow through macropores can contribute to storm period streamflow water may reach the channel system from a proportion of the catchment which varies with antecedent moisture conditions and storm duration and intensity but which may attain 100 in moderate to large rain events because of the drier climate and deeper soils subsurface flow contributions to stormperiod streamflow should be less important in the big bush area and particularly in the craigieburn area where the parent materials shattered sandstone or ancient scree deposits do not provide an impermeable layer which diverts flow laterally

vashon drift definition of the formation in the georgia depression southwest british columbia vashon drift was deposited during the fraser glaciation late wisconsinan at the time of maximum expansion of the southwestern part of the cordilleran ice sheet when it filled the georgia depression about 14 500 years ago the drift is present throughout the depression and comprises till and glaciofluvial and glaciolacustrine sediments derived from source areas surrounding the coastal trough it is overlain by capilano sediments and underlain by quadra sand also of fraser age drift deposition was diachronous and complex probably caused by alpine glaciers coalescing in the trough with the ice margin repeatedly grounding and floating in seawater studies of bedrock striae till fabrics and clast provenance reveal that vashon ice movement was generally southward although locally controlled by topography a time space diagram is presented that confirms the long held hypothesis that advance and decay of vashon ice were rapid

lateral subsurface stormflow and solute transport in a forested hillslope a combined measurement and modeling approach preferential flow dominates water movement and solute transport in boreal forest hillslopes however only a few model applications to date have accounted for preferential flow at forest sites here we present a parallel and coupled simulation of flow and transport processes in the preferential flow domain and soil matrix of a forested hillslope section in kangaslampi finland using a new three dimensional physically based dual permeability model our aim is to simulate lateral subsurface stormflow and solute transport at the slope during a chloride tracer experiment and to investigate the role of preferential flow in the tracer transport the model was able to mimic the observed tracer transport during tracer irrigation but overestimated the dilution velocity of the tracer plume in the highly conductive soil horizons near the soil surface after changing the irrigation to tracer free water according to the model 140 times more chloride was transported downslope in the preferential flow domain than in the soil matrix during the tracer irrigation the simulations showed together with reference simulations with a traditional one pore domain model that a two pore domain approach was required to simulate the observed flow and transport event the event was characterized by the transmissivity feedback phenomenon and controlled by preferential flow mechanisms in particular by lateral by pass flow according to our results accounting for the slow flow and fast flow domains of soil as well as the water and solute exchange between the domains is essential for a successful simulation of flow and solute transport in preferential flow dominated hillslopes

subsurface lateral preferential flow network revealed by time lapse ground penetrating radar in a hillslope subsurface lateral preferential flow lpf has been observed to contribute substantially to hillslope and catchment runoff however the complex nature of lpf and the lack of an appropriate investigation method have hindered direct lpf observation in the field thus the initiation persistence and dynamics of lpf networks remain poorly understood this study explored the application of time lapse ground penetrating radar gpr together with an artificial infiltration to shed light on the nature of lpf and its dynamics in a hillslope based on our enhanced field experimental setup and carefully refined gpr data postprocessing algorithms we developed a new protocol to reconstruct lpf networks with centimeter resolution this is the first time that a detailed lpf network and its dynamics have been revealed noninvasively along a hillslope real time soil water monitoring and field soil investigation confirmed the locations of lpf mapped by time lapse gpr surveys our results indicated the following 1 increased spatial variations of radar signals after infiltration suggested heterogeneous soil water changes within the studied soil which reflected the generation and dynamics of lpf 2 two types of lpf networks were identified the network at the location of soil permeability contrasts and that formed via a series of connected preferential flow paths and 3 the formation and distribution of lpf networks were influenced by antecedent soil water condition overall this study demonstrates clearly that carefully designed time lapse gpr surveys with enhanced data postprocessing offer a practical and nondestructive way of mapping lpf networks in the field thereby providing a potentially significant enhancement in our ability to study complex subsurface flow processes across the landscape

lagoon subsidence and tsunami on the west coast of new zealand abstract sediment core and trench data from a coastal lagoon on the west coast of the south island new zealand are used to investigate evidence for co seismic subsidence and associated tsunami inundation physical data are used to document a salt marsh soil buried 80 cm below the modern sediment surface that is locally covered by a gravelly sand bed the sediment record also contains geochemical and biological diatom and foram evidence for abrupt changes in salinity of lagoon waters that link to subsidence tsunami flooding and to the open versus closed state of the lagoon tidal entrance at the local scale these relationships allow for separation of tsunami evidence from other agents of environmental change in the lagoon we also propose a conceptual connection between these local changes and regional drivers of landscape development most notably major earthquakes and resultant pulses in sediment supply to the coast

preferential flow mechanisms identified from staining experiments in forested hillslopes field staining experiments in five different plots at two sites in japan okaya in nagano prefecture and konohara in mie prefecture were undertaken to improve understanding of subsurface stormflow runoff within organic layers of natural forested hillslopes this type of shallow lateral subsurface flow specifically referred to as biomat flow was observed only at the okaya site based on staining experiments conducted under controlled water application rates when the same irrigation rate 50 100 mm h 1 was applied to the konohara site overland flow without a significant shallow subsurface component was the dominant flow mechanism even in gently sloping 15 20 forest soils at the okaya site biomat flow was responsible for lateral dye transport over much longer distances than sub surface flow in the matrix of mineral soil layers based on analysis of staining pattern images observed in the okaya site we conclude that i the organic biomat layer could be divided into two sub layers of different structure ii biomat flow transported the dye tracer longer distances than subsurface flow in the matrix and iii the biomat layer topography affected biomat flow by generating preferential flowpaths and subsequent percolation into the deeper soil based on field experimental results and pore scale consideration of water infiltration into pores of soils with varying wettability properties we hypothesized and developed a conceptual model for two key biomat flow mechanisms the first mechanism considers lateral subsurface flow due to a permeability contrast between the much more porous and hence permeable biomat layer and the underlying mineral soil the second mechanism involves a hydrophobic soil layer between the biomat and the underlying mineral soil flow across the hydrophobic layer is believed to occur when a threshold pore pressure is exceeded i e as a result of a perched water table within the biomat layer lower pore pressures are needed to initiate flow when preferential flow paths exist that are less hydrophobic than the surrounding organic layers numerical models of catchment hydrology should include lateral biomat flow when such layers are present in hillslope soils in addition to typical subsurface flow within the soil matrix this article is protected by copyright all rights reserved

hydrologic impacts of landslide disturbances implications for remobilization and hazard persistence landslides typically alter hillslope topography but may also change the hydrologic connectivity and subsurface water storage dynamics in settings where mobile materials are not completely evacuated from steep slopes influences of landslide disturbances on hillslope hydrology and susceptibility to subsequent failures remain poorly characterized since landslides often recur at the site of previous failures we examine differences between a stable vegetated hillslope vh and a recent landslide ls these neighboring hillslopes exhibit similar topography and are situated on steep landslide prone coastal bluffs of glacial deposits along the northeastern shore of puget sound washington our control hillslope vh is mantled by a heterogeneous colluvium supporting a dense forest in early 2013 our test hillslope ls also supported a forest before a landslide substantially altered the topography and disturbed the hillslope in 2015 we observed a clay rich landslide deposit at ls with sparse vegetation and limited root reinforcement soil structures and macropores our characterization of the sites also found matrix porosity and hydraulic conductivity are both lower at ls continuous monitoring during 2015 2016 revealed reduced effective precipitation at vh due to canopy interception an earlier seasonal transition to near saturated conditions at ls and longer persistence of positive pore pressures and slower drainage at ls both seasonally and between major storm events these differences along with episodic complex slope failures at ls support the hypothesis that despite a reduced average slope other disturbances introduced by landsliding may promote the hydrologic conditions leading to slope instability thus contributing to the persistence of landslide hazards

rossby wave packets on the midlatitude waveguide a review abstractrossby wave packets rwps are rossby waves for which the amplitude has a local maximum and decays to smaller values at larger distances this review focuses on upper tropospheric transient rwps along the midlatitude jet stream their central characteristic is the propagation in the zonal direction as well as the transfer of wave energy from one individual trough or ridge to its downstream neighbor a process called downstream development these rwps sometimes act as long range precursors to extreme weather and presumably have an influence on the predictability of midlatitude weather systems the paper reviews research progress in this area with an emphasis on developments during the last 15 years the current state of knowledge is summarized including a discussion of the rwp life cycle as well as rossby waveguides recent progress in the dynamical understanding of rwps has been based in part on the development of diagnostic methods these methods include algorithms to identify and track rwps

dye tracer visualization of flow patterns and pathways in glacial sandy till at a boreal forest hillslope abstract dyes are valuable tracers in visualizing flow patterns and pathways in soil we applied the dye acid blue 9 to unsaturated and saturated soil profiles at a boreal forest hillslope consisting of glacial sandy till and determined the soil physical properties from soil samples the objective was to characterize preferential flowpaths investigate their porosity extent and connectivity and complement earlier findings on subsurface flow formation at the site according to the results preferential flowpaths were formed by roots erosion related to soil water flow freezing thawing cycles and soil fauna the role of roots and stones in the formation of preferential flowpaths was emphasized porosity of preferential flowpaths was 5 1 1 8 and they extended to a depth of about 55 cm from the soil surface the deepest roots reached the same depth when the soil saturated individual preferential flowpaths self organized into continuous and well connected lateral flow systems along the slope at the slope shoulder preferential flow network covering the entire soil profile as well as preferential flowpaths on the underlying bedrock surface were considered crucial for runoff generation in the midslope area runoff generation was characterized by lateral preferential flow and the transmissivity feedback phenomenon at the slope foot preferential flowpaths in soil below the eluvial horizon were the major runoff contributors a full saturation of the soil profile at the slope is unlikely under natural conditions however lateral flow was found to occur also in unsaturated soil

sediment detachment and transport processes associated with internal erosion of soil pipes subsurface flow can be an important process in gully erosion through its impact on decreasing soil cohesion and erosion resistance as soil water content or pressure increases and more directly by the effects of seepage forces on particle detachment and piping the development of perched water tables in duplex soils fosters lateral flow that can result in seepage at the surface of hillslopes and or formation of soil pipes by internal erosion of lateral preferential flow paths continued internal erosion of soil pipes can lead to gullies dam and levee failures however the processes involved in particle and aggregate detachment from soil pipe walls and transport processes within soil pipes have not been well studied or documented this paper reviews the limited research on sediment detachment and transport in macropores and soil pipes and applies the knowledge learned from the much more extensive studies conducted on streams and industrial pipes to hydrogeologic conditions of soil pipes knowledge gaps are identified and recommendations are made for future research on sediment detachment and transport in soil pipes

stream scanning laser system electric sensing counter and settling grain size analysis a comparison using reference materials and marine sediments abstract surface and deep sea core sediments and two sets of standards were measured by three different techniques galai cis 1 laser system coulter counter ta ii and micromeritics sedigraph 5000d in order to compare the galai results with the other two the differences between the three types of measuring device turned out to be greater in sediments than in standards and were attributed to the physical properties shape density and composition of the particles complexity of the matrix comparison of moment statistics showed that the galai determines coarser grain sizes than the coulter and finer than the sedigraph particularly as regards analysis of surface sediments the relationships between galai and sedigraph were estimated using analysis of variation residuals within individual intervals the analysis showed a higher variability of residuals for the coarser fractions 8 16 m and 16 32 m with respect to the finer 2 4 m and 4 8 m fractions the

vertical structure of midlatitude analysis and forecast errors abstract the dominant vertical structures for analysis and forecast errors are estimated in midlatitudes using a small ensemble of operational analyses errors for fixed locations in the central north pacific and eastern north america are selected for comparing errors in regions with relatively low and high observation density respectively results for these fixed locations are compared with results for zonal wavenumber 9 which provides a representative sample of baroclinic waves this study focuses on deviations from the ensemble mean for meridional wind and temperature at 40 n these quantities are chosen for simplicity and because they capture dynamical and thermodynamical aspects of midlatitude baroclinic waves results for the meridional wind show that analysis and forecast errors share the same dominant vertical structure as the analyses this structure peaks near the tropopause and decays smoothly toward small values in the middle and lower troposphere the dominant vertical structure for analysi

distribution patterns of the elements in the ocean a synthesis the observed partition patterns of elements between a marine solid phase e g pelagic clays deep sea manganese nodules seamount manganese crusts and plankton and seawater can be to the first approximation explained by the james and healy adsorption model except for ce co mn pb and tl which are concentrated in the solid phase through oxidative uptake processes in other words the composition of seawater is mainly controlled by the compositions of source materials i e the crustal igneous rocks and primary magmatic volatiles and the physicochemical principles regulating the adsorption processes of various chemical species in seawater onto oceanic pelagic clays

influence of antecedent soil moisture on hydraulic conductivity in a series of texture contrast soils antecedent soil moisture significantly influenced the hydraulic conductivity of the a1 a2e and b21 horizons in a series of strong texture contrast soils tension infiltration at six supply potentials demonstrated that in the a1 horizon hydraulic conductivity was significantly lower in the wet treatment than in the dry treatment however in the a2e horizon micropore and mesopore hydraulic conductivity was lower in the dry treatment than the wet treatment which was attributed to the precipitation of soluble amorphous silica in the b21 horizon desiccation of vertic clays resulted in the formation of shrinkage cracks which significantly increased near saturated hydraulic conductivity and prevented the development of subsurface lateral flow in the dry treatment in the wet treatment the difference between the hydraulic conductivity of the a1 and b21 horizons was reduced however lateral flow still occurred in the a1 horizon due to difficulty displacing existing soil water further down the soil profile results demonstrate the need to account for temporal variation in soil porosity and hydraulic conductivity in soilwater model conceptualisation and parameterisation

comparisons of dry ert diachronic ert and the spectral analysis of surface waves for estimating bedrock depth in various mediterranean landscapes abstract bedrock depth provides important information for many applications such as groundwater modelling the estimation of soil water availability and crop production potential direct estimates of bedrock depth from destructive soil observations are discontinuous and too expensive to be used in large areas geophysical methods are often cited as possible alternatives however their ability to provide reliable estimations of bedrock depth relies greatly on local site characteristics therefore this study examines the ability of electrical resistivity tomographie ert in dry conditions diachronic ert and the spectral analysis of surface waves sasw method to determine bedrock depth bd in different geopedological contexts that are representatives of the mediterranean landscape southern france sasw was performed using the data that were measured in the field with classical seismic equipment impulse source and geophones along a transect in each study site in the same place transects of ert wenner schlumberger array 1 m electrode spaced were measured under wet and dry conditions to calibrate the geophysical measurements 131 boreholes from two to 5 m deep were interpreted to determine the bedrock depth dry ert diachronic ert and sasw were found to have highly variable performances for the estimation of bedrock depth in all geopedological contexts sasw correctly estimated the bedrock depth rmse 0 3 0 7 m in all situations except in the case of shallow soils conversely dry ert only estimated bedrock depth rmse 0 2 m in the case of a high contrast of the resistivity between the soil and bedrock by analysing the pattern of the water uptake by grapevine diachronic ert determined the bedrock depth in the case of very low contrasts in resistivity rmse 0 5 according to a prior pedological knowledge such soil maps the combination with the use of a sensor based on different physical parameters may enhance the bedrock detection

lithological controls on hydrological processes that trigger shallow landslides observations from granite and hornfels hillslopes in hiroshima japan abstract a comprehensive understanding of landslide processes is critical in explaining the spatial distribution of shallow landslides and rainfall thresholds for triggering landslides under different bedrock conditions here we discuss the observed shallow landslide mechanisms on adjacent granite and hornfels hillslopes in northern hiroshima city western japan the thickness structure and geotechnical properties of the shallow subsurface materials were characterized via field based surveys and laboratory experiments the observed pore water pressure responses in the soil layer due to rainfall infiltration were monitored using tensiometers in the granite hillslopes the rapid percolation of rainwater from the near surface high permeability sandy soil to the low permeability saprolite at depth and the limited water storage capacity of the saprolite led to the development of a saturated zone that extended upward from the base of the soil layer the cohesionless soils in the granite hillslopes can slip along the boundary between the weak upper layer and stiff lower layer once this boundary experiences weak positive pore fluid pressure as the perched water table rises from the underlying saprolite boundary conversely the hornfels hillslopes are covered by cohesive soils in which permeability decreases with depth which contributes to the formation of a perched groundwater body above the lower soil layer when a large positive pressure acts on the potential sliding surface the upper soil layer can slip along the hydraulic and mechanical discontinuity between two soil layers in the hornfels hillslopes these results indicate that the underlying bedrock lithology controls the subsurface structures that shape the hydraulic and mechanical properties of the hillslope materials as well as their subsurface hydrological processes which in turn influence the potential for shallow landslides

subsurface flow velocities in a hillslope with lateral preferential flow 1 our understanding of hillslope subsurface flow relies on assumptions about how storm characteristics affect the hillslope runoff response experiments in hillslopes dominated by preferential flow features often show that runoff is dynamic and is affected by antecedent conditions rainfall conditions and position of the slope we applied tracers to a hillslope under natural and steady state flow boundary conditions to determine the relationship between lateral tracer velocities and various hillslope lengths and storm indicators tracer velocities were similar to the fastest velocities measured in other similar experiments the velocities were dependent on the boundary conditions and slope length and the subsurface flow velocity was most closely related to the 1 h rainfall intensity unlike some studies there was little correlation between our measured flow velocities and storm volume or antecedent conditions we attributed this to the hillslope characteristics and the relatively consistent wet antecedent conditions during the experiments this experiment showed that the connectivity of the hillslope preferential flow network is an important factor governing the average subsurface flow velocity

a case study of cyclogenesis using a model hierarchy abstract it is universally agreed that cyclogenesis in midlatitudes occurs through baroclinic conversion of the potential energy available from an initial state the mechanical process by which that conversion takes place is a perennial subject of discussion at least as far back as the 1950s it was recognized that in any practical forecast problem the initial condition is influential observational research continues to confirm the prevalence of tropopause level perturbations preceding surface cyclogenesis the observations also suggest that the growing disturbances have time varying vertical structures relating these observations to the classical linear theory of baroclinic instability is not immediately obvious since in the latter the precise form of the initial condition is not important and the theory predicts cyclogenesis with a fixed in time vertical structure these differences between theory and observations are but a few of the many that have been recognized and treated in modified theorie

how do disconnected macropores in sloping soils facilitate preferential flow runoff from hillslopes is generated by processes such as infiltration excess and saturation overland flow subsurface stormflow and subsurface return flow preferential flow through macropores can affect any one of these runoff generation processes field studies at the hitachi ohta experimental watershed in japan have noted that self organization processes may manifest the connectivity of such subsurface flow paths particularly via macropores from hillslopes to stream channels it is well established from soil physics principles that the connectivity of macropore networks depends on soil wetness and this has been shown experimentally at hitachi ohta where subsurface flow and streamflow respond to thresholds of wetness numerical solutions to the three dimensional richards equation are derived for a sloping soil block containing a population of disconnected macropores of various sizes shapes and orientations solutions for the case of steady water flux applied to the surface of the soil block are evaluated to determine the conditions where the disconnected macropores become active in the flow process results show that subsurface flow is directed through the preferential flow network in the saturated portion of the soil but bypasses the macropores in the drier regions the preferential flow network expands as the degree of saturation increases the expanding network of active macropores leads to less resistance to overall flow in the domain and access to increased volumes of the flow domain although the individual macropores are disconnected it is argued that large localized hydraulic gradients can potentially lead to preferred zones of subsurface erosion in addition to the importance of these findings related to stormflow generation in catchments they add support to the concept of self organization of subsurface flow systems in soils copyright 2010 john wiley sons ltd

shallow lateral flow from a forested hillslope influence of antecedent wetness abstract a 5 m wide soil pit at the base of a forested hillslope in coastal british columbia was instrumented for studying subsurface flow processes during rainstorms three typical low intensity autumn rainfall events with different antecedent moisture conditions are assessed outflow from the organic horizon was captured and measured by a single trough and outflow from the mineral horizon above compact glacial till and bedrock was measured separately for three adjacent sections of the soil pit for two storms that were preceded by dry conditions lateral outflow from the organic horizon occurred although the water table did not rise up to the organic horizon however the calculated effective contributing area was small 2 and the effective contributing slope length was short 170 m 2 and the effective contributing slope length 36 m were substantially greater for the wet antecedent storm compared to the dry storm events shallow lateral flow over unsaturated soil is therefore unlikely to be a significant contributor to storm runoff at such forested sites flow at the organic horizon mineral soil interface may contribute to interconnected preferential flow pathways during wetter antecedent conditions

fine scale structure of the extratropical tropopause region 1 a vertically high resolved climatology of the thermal and wind structure of the extratropical tropopause region is presented the climatology is based on data from 80 u s radiosonde stations covering the period 1998 2002 time averages for each radiosonde station are computed using the tropopause as a common reference level for all vertical profiles within the mean a strong inversion at the tropopause in the mean vertical temperature gradient is uncovered that is temperature strongly increases with altitude within the lowermost stratosphere this tropopause inversion layer exists on average throughout the investigated extratropics about 30 n to 70 n accordingly the static stability parameter shows considerably enhanced values within the lowermost extratropical stratosphere compared to typical extratropical stratospheric values further aloft conventional averages are not able to capture the tropopause inversion layer mean profiles of the horizontal wind show behavior qualitatively corresponding to thermal wind balance winter and summer exhibit distinctly different climate states in the extratropical tropopause region an approximated potential vorticity is considered and found to be close to well mixed within the troposphere as well as within the tropopause inversion layer this suggests the view of the tropopause inversion layer as representing a dynamically active atmospheric layer some potential implications are discussed

glaciotectonic structures as useful ice movement indicators in glacial deposits four canadian case studies glaciotectonic deformation structures are useful directional indicators of ice movement but are rarely reported by north american authors being three dimensional they are commonly conspicuous in cleaned sections measuring just a few of them can provide accurate ice movement directions at a site and they assist in deciphering the interaction of past glaciers and their substrata this paper concentrates on structures generally less than 10 m long in unconsolidated sediments that were induced by overriding glacial ice examples and interpretations of various types of structures are presented in four new canadian case studies from british columbia and southern ontario that illustrate different deformational circumstances in sediments of various ages

vegetation influences near surface hydrological characteristics on a surface coal mine in eastern usa abstract mining processes alter natural landscapes worldwide and methods for restoration of mined areas are widely studied establishment of vegetation is essential to mined land restoration prior research has addressed vegetative influence on erosion and runoff but effects of vegetation type on surface hydrologic processes are less studied we measured infiltration rates and observed subsurface flow paths in mine soils on a reforested area and a grassed area on a former surface coal mine in the eastern united states the two areas were constructed and reclaimed fourteen years prior to our study using processes similar in all aspects except vegetation minidisk tension infiltrometers and brilliant blue fcf dye staining analyses were utilized to evaluate near surface flow processes in the vegetated mine soils mean infiltration rates were 16 5 10 7 cm h 1 and 10 4 7 7 cm h 1 for the reforested and grassed areas respectively infiltration rates hydraulic conductivities dye coverage and dye stained areas were significantly higher in the reforested area the grassed area had constant dye coverage with depth but more flow paths than the reforested area a transition from vegetation controlled subsurface flow to abiotic control at greater depths was evident in the stained soil profiles results highlight the heterogeneous nature of mine soils and the influence of vegetation type in development of mine soil hydrologic processes

developing wave packets in the north pacific storm track developing wave packets in the western north pacific storm track are diagnosed observationally an abrupt upstream edge to baroclinic wave activity over the western north pacific facilitates comparisons between the observational results and previous theoretical predictions on the spatiotemporal evolution of an impulse disturbance results show that surface cyclogenesis events are preceded by a sharply peaked wave packet that originates poleward of the himalaya plateau and develops rapidly across the north pacific to north america composite wave packet structure is broadly consistent with linear theory for idealized models such as eady s the longitude height structure of the mature packet reveals deep growing waves with horizontal wavelengths of approximately 4000 km near the packet peak downstream from the peak amplitude decays exponentially and wavelength decreases approximately linearly to about 2500 3000 km at the leading edge meridional potential vorticity gradients are concentrated near the tropopause in contrast to linear theory the packets show an abrupt upstream edge and no evidence of upstream development as the packet travels through the along stream variations of the pacific jet stream the packet peak and leading edge group velocity vary these accelerations change the packet length and suggest that the pacific jet may act to focus the packets a sample of north atlantic storm track events reveals similar results and suggests that the atlantic storm track is often seeded by wave packets that originate over the western north pacific ocean in contrast atlantic packets refract equatorward and become trapped on the subtropical jet to the south of himalaya plateau suggesting perhaps less potential for seeding disturbances in the pacific storm track

assessment of grass root effects on soil piping in sandy soils using the pinhole test abstract soil piping is an important land degradation process that occurs in a wide range of environments despite an increasing number of studies on this type of subsurface erosion the impact of vegetation on piping erosion is still unclear it can be hypothesized that vegetation and in particular plant roots may reduce piping susceptibility of soils because roots of vegetation also control concentrated flow erosion rates or shallow mass movements therefore this paper aims to assess the impact of grass roots on piping erosion susceptibility of a sandy soil the pinhole test was used as it provides quantitative data on pipeflow discharge sediment concentration and sediment discharge tests were conducted at different hydraulic heads i e 50 mm 180 mm 380 mm and 1020 mm results showed that the hydraulic head was positively correlated with pipeflow discharge sediment concentration and sediment discharge while the presence of grass roots expressed as root density was negatively correlated with these pipeflow characteristics smaller sediment concentrations and sediment discharges were observed in root permeated samples compared to root free samples when root density exceeds 0 5 kg m 3 piping erosion rates decreased by 50 compared to root free soil samples moreover if grass roots are present the positive correlation between hydraulic head and both sediment discharge and sediment concentration is less pronounced demonstrating that grass roots become more effective in reducing piping erosion rates at larger hydraulic heads overall this study demonstrates that grass roots are quite efficient in reducing piping erosion rates in sandy soils even at high hydraulic head 1 m as such grass roots may therefore be used to efficiently control piping erosion rates in topsoils

comparison of wave packets associated with extratropical transition and winter cyclones abstractdifferences in the development of wave packets associated with midlatitude cyclones and the extratropical transition et of tropical cyclones in the western north pacific wnp and atlantic basins are diagnosed observationally by compositing climate forecast system reanalysis cfsr data over a 32 yr period and applying the null hypothesis of no difference in the development structure propagation or downstream extent while the development of midlatitude cyclones during the fall august october and winter november march amplifies a preexisting wave packet moving through the midlatitude storm track et is associated with the quasi stationary amplification of the midlatitude flow the et cases involving the interaction of the decaying tc with a preexisting midlatitude trough are associated with a greater downstream amplitude and longer lasting downstream response than et cases that do not involve the interaction with a trough in the wnp et wave packets have greater amplitude than those asso

development of algebra algorithms for automated generation of grain size distribution maps the grain size distribution of sediments is a fundamental characteristic in understanding the earth s surface environments and an essential tool in classifying sedimentary environments grain size data provide important information on the energy and dynamics of depositional environments and aid our understanding of sediment transport ternary diagrams tds are useful and conventional tools to classify sediments on the basis of relative grain size i e gravel sand mud or sand silt clay the development of spatial modelling in a geographical information system gis can assist in treating computing and displaying sedimentological data such as grain sizes in this work four map algebra ma algorithms are written in a gis environment to automatically produce maps depicting the spatial distribution of sediment texture classes based on the most frequently used grain size tds the shepard classification and flemming classification for sand silt clay components and the folk et al classification and blair and mcpherson classification for sand gravel mud components the proposed method allows rapid assessments by producing map distributions of the parameters most widely used in sedimentology copyright 2007 john wiley sons ltd

comparison of laser grain size analysis with pipette and sieve analysis a solution for the underestimation of the clay fraction classically the grain size of soil and sediment samples is determined by the sieve method for the coarse fractions and by the pipette method based on the stokes sedimentation rates for the fine fractions results from the two methods are compared with results from laser diffraction size analysis which is based on the forward scattering of monochromatic coherent light from a point of view of laboratory efficiency the laser sizing technique is far superior accuracy and reproducibility are shown by measurements on certified materials it appears that laser grain size measurements of certified materials correspond very well with the certificated measurements tests were also done on a set of randomly selected sediments of fluvial aeolian and lacustrine origin except for the 2 m clay fraction there is a coarsening of the mean diameter of one to two size classes 0 25 caused by the non sphericity of the particles the platy form of the clay particles induces considerable differences eight size classes between pipette and laser measurements the 2 m grain size defined by the pipette method corresponds with a grain size of 8 m defined by the laser particle sizer for the studied sediments using a higher grain size level for the clay fraction when laser analysis is applied enables workers in the geological and environmental field to compare classical pipette analysis with a laser sizing technique

interelement relationship in abyssal pacific ferromanganese nodules and associated pelagic sediments abstract by r mode factor analysis and enrichment factor calculations most of the elements in abyssal ferromanganese nodules and associated pelagic sediments excluding common authigenic minerals like apatite barite opal and carbonates are found to be preferentially concentrated in one of the following three major phases aluminosilicates e g al si sc ga cr be na k rb and cs fe oxides e g fe p s v se te as b sn u hg pb ti ge y zr nb pd in rare earths hf th pa pu am ru and bi and mn oxides e g mn tl ag cd mg ca ba ra co ni cu zn mo sb and probably w the specific association of elements with these three phases can be explained by the difference in chemical forms of elements in seawater and by fundamental differences in physicochemical properties e g the ph of zero point of charge and dieletric constant of these three phases

terrigenous sedimentation processes along the continental margin off nw africa implications from grain size analysis of seabed sediments the terrigenous fraction of seabed sediments recovered along the north west african continental margin illustrates spatial variability in grain size attributed to different transport mechanisms three subpopulations are determined from the grain size analyses n 78 of the carbonate free silt fraction applying an end member modelling algorithm g j weltje 1997 the two coarsest endmembers are interpreted as representing aeolian dust and the fine grained end member is related to fluvial supply the end member model thus allows aeolian fallout to be distinguished from fluvial sourced mud in this area the relative contributions of the end members show distinct regional variations that can be related to different transport processes and pathways understanding present day sediment dispersal and mixing is important for a better understanding of older sedimentary records and palaeoclimate reconstructions in the region

soil pipe flow tracer experiments 2 application of a streamflow transient storage zone model soil pipes are important subsurface flow pathways in many soil erosion phenomena however limited research has been performed on quantifying and characterizing their flow and transport characteristics the objectives of this research were to determine the applicability of a streamflow model with transient storage in deriving flow and transport characteristics of soil pipes tracer data from pulse inputs were collected in four different soil pipes after a fluorescein dye was injected in the upstream end of each soil pipe network in three branches west middle and east of a main catchment and a back catchment in goodwin creek experimental watershed in mississippi multiple sampling stations were positioned along each soil pipe network the transient storage zone model otis p was executed inversely to estimate transport parameters by soil pipe reach such as the soil pipe cross sectional area a soil storage zone cross sectional area as and exchange rate between the soil pipe and the soil storage zone s model convergence was achieved and simulated breakthrough curves of the reaches were in good agreement with actual tracer data for eight of the nine reaches of the three branches of the main catchment and five of the seven reaches of the back catchment soil pipe simulation parameters for the soil pipe networks were similar to the range of values reported for flow and transport characteristics commonly observed in streams inversely estimated soil pipe flow velocities were higher with increased tortuosity which led to a smaller cross sectional areas predicted for the soil pipe flowpaths while other parameters were not sensitive to tortuosity in general application of one dimensional transport with inflow and storage p to this unique soil pipe condition suggested larger transient storage as and s compared with most stream systems this was hypothesized to be because of relatively higher ratio of the wetted perimeter to flow area in the soil pipe the hydraulic roughness of the soil pipe potential retention in collapsed portions of the pipe and interaction with smaller preferential flow systems copyright 2015 john wiley sons ltd

sedimentation and time of transition techniques for measuring grain size distributions in lagoonal flats comparability of results abstract a comparative study was performed of three instruments used to measure thegrain size distribution of thirty sediment samples from shallow lagoonal ats the hydrometer the sedigraph 5100 and the cis 1 the hydrometer andsedigraph are based on sedimentation whereas the cis 1 uses the time oftransition the percentage of the samples accounted for by the 8 lm fractionwas not affected by the technique used but this was not the case with the clayfraction 2 lm due to its relative independence from the analytical methodapplied the 8 lm fraction can be used in ternary diagram classi cations thisfraction also has an environmental signi cance in coastal lagoons in terms ofhydrodynamics organic enrichment and macrozoobenthos assemblages thelinear relationships obtained in this study may provide useful operationalindications for similar studies keywords grain size analysis lagoon mud non sortable silt sortable silt time of transition introductionalthough common standards of analysis have notyet been established by the scienti c community grain size and grain size distribution are keyfactors in sedimentology and landscape evolution goossens 2008 sediment grain size data arecommonly used for textural classi cation but thedetails remain unresolved for lagoon sediments lagoons may display a large variety of sedimentpatterns depending on the relative strength ofwaves and tides nichols boon 1994 grain size distribution is certainly one of the morehelpful tools for describing the environmentalconditions in lagoon systems because ne grained material correlates strongly withpollutants in addition variability in chemical physical and hydrographical parameters is alwaysrelatedtovariationinsedimentgrain size kjerfve 1994 particle dimensions therefore describeenvironmental conditions and provide informa tion about processes acting on the ecosystem theymay thus be regarded as an environmental tracer for these reasons it is very important to charac terize the grain size of bottom sediments indeed grain size data are essential for the modelling andmanagement of lagoon environments flemming 2000 proposed an updated versionof the texture ternary diagram reineck siefert 1980 pejrup 1988 which increases the range ofapplication and the environmental sensitivity oftextural sediment classi cation the classi ca tion incorporates a genetic element by distin guishing between different hydrodynamicregimes although molinaroli et al 2009a b showed that the 8 lmandca 20 lm fractionscould be used to classify lagoonal sediments interms of their hydrodynamics chang et al 2006 2007 showed that 8 lm is an important size limitin the wadden sea sediments delimiting thetransition between cohesive ocs and aggregatesand non cohesive single grains the debatesedimentology 2011 58 1407 1413

relationships between hydrodynamic parameters and grain size in two contrasting transitional environments the lagoons of venice and cabras italy abstract a comparison was made of shallow water sediments from the lagoon of venice lv and the lagoon of cabras lc comparing depositional environments and exploring the relationships between hydrodynamics and sedimentological parameters the two water bodies are very different in size lv 360 km2 lc 22 km2 and the sediments predominantly consist of silty clay lv mz 26 m lc mz 6 m however there are large differences between the two lagoons with respect to sand lv mean 19 lc mean 3 and clay lv mean 20 lc mean 45 contents the lagoon of venice mean depth 1 m can be considered a tidal basin whereas the lagoon of cabras mean depth 2 m has the character of a coastal lake in which wind is the main hydrodynamic forcing factor a comparison of sediment grain size distributions with water circulation patterns in different parts of the lagoons highlighted some interesting differences grain size analyses of samples reveal a deficiency of particles around 8 m in the lc which is interpreted as reflecting the transition between cohesive flocs aggregates and non cohesive coarser silt particles while the transition limit in the lv is 20 m thus particles are cohesive below 8 m in the lc and below 20 m in the lv this is probably because of the differences in the clay silt ratio which is much lower in the lv 0 3 than in lc 1 conferring a silt dominated network structure on most of the lv sediments the hydrographical data used were root mean square velocity rmsv and water residence time wrt computed under the main forcing conditions the results show a general correlation between rmsv and sortable silt in the lc and between rmsv and coarser sediments 63 105 m in the lv some significant differences between the lagoons were detected in the degree of correlation between wrt and grain size root mean square velocity 7 cm s 1 in the lv and 3 cm s 1 in the lc was a greater forcing factor in the lc than in the lv conversely wrt which is on average 16 days in the lv and 19 days in the lc has more influence in the lv this study highlights the usefulness of comparing environments with different hydrodynamic energies e g tidal and or wind driven currents to elucidate and thereby improve our understanding of the processes governing the spatial distribution of sedimentological features the transport mechanisms of sediments and the relationship between them the results demonstrate that the approach outlined in this study has the potential to provide a universal hydro sedimentological classification scheme

dynamic earth system and ecological controls of rainfall initiated landslides abstract rainfall initiated landslides continue to inflict damages and loss of life throughout the world processes and mechanisms revealed from hydrological geomorphic geotechnical pedological geological hydrochemical and biological investigations have advanced our understanding of these effects on slope stability however the interactions amongst these processes and attributes as they affect the initiation and propagation of landslides are not as well understood too often landslide studies are conducted from only one or at most two of these perspectives moreover while precipitation and hydrology are recognized as dynamic influences the earth system and ecological effects are often assumed to be static we assess the interplay of these processes related to landslides triggered by positive pore water accretion and loss of soil suction each of these conditions arguably requires a different view on the processes that cause slope failure and predictive approaches this review starts from the perspective of dynamic adapting earth and ecological systems and discusses how these attributes relate to landslide initiation mode location and timing specifically the role that large and small scale preferential flow plays in both contributing to and mitigating instability is elucidated including effects of bedrock exfiltration we also examine how and under what conditions these pathways manifest in different soils lithology and landforms the multiple effects of rhizosphere processes on slope stability are discussed including root reinforcement evaporation from canopies and litter layers transpiration and the role of root structure affecting preferential flow paths rainfall initiated landslides involve highly dynamic hydrologic earth surface and ecological processes that persist over a range of spatial and temporal scales however guidance for overcoming these challenges has been elusive a conceptual framework is presented to shed light on these dynamic and interactive processes that should lend insights into why and when certain slopes fail during storms while other seemingly similar slopes do not fail such advances will benefit landslide hazard assessments and disaster responsiveness protocols

runoff process on a steep forested slope abstract three slope units are defined by combining nine basic slope types a convergent slope unit is called a zero order basin because it combines a slope and a stream field measurements of the runoff process of stormflow on pliocene slopes are presented pipe flow and saturated overland flow play an important part on convergent colluvial slope units surface soils significantly influence saturated throughflow on creeping middle slopes the depth of weathering has a major effect on initial moisture storage for residual and creeping slopes a subsurface storm flow pattern on a typical pliocene slope is reconstructed based on the field measurements

a conceptual model of preferential flow systems in forested hillslopes evidence of self organization preferential flow paths are known to be important conduits of subsurface stormflow in forest hillslopes earlier research on preferential flow paths focused on vertical transport however lateral transport is also evident in steep forested slopes underlain by bedrock or till macropores consisting of decayed and live roots subsurface erosion surface bedrock fractures and animal burrows form the basis of a backbone for lateral preferential flow in such sites evidence from field studies in japan indicates that although individual macropore segments are generally 0 5 m in length they have a tendency to self organize into larger preferential flow systems as sites become wetter staining tests show clear evidence of interconnected macropore flow segments including flow within decayed root channels and subsurface erosion cavities flow in small depressions of the bedrock substrate fracture flow in weathered bedrock exchange between macropores and mesopores and flow at the organic horizon mineral soil interface and in buried pockets of organic material and loose soil here we develop a three dimensional model for preferential flow systems based on distributed attributes of macropores and potential connecting nodes e g zones of loose soil and buried organic matter we postulate that the spatially variable and non linear preferential flow response observed at our japan field site as well as at other sites is attributed to discrete segments of macropores connecting at various nodes within the regolith each node is activated by local soil water conditions and is influenced strongly by soil depth permeability pore size organic matter distribution surface and substrate topography and possibly momentum dissipation this study represents the first attempt to characterize the spatially distributed nature of preferential flow paths at the hillslope scale and presents strong evidence that these networks exhibit complex system behaviour

rossby wave initiation by recurving tropical cyclones in the western north pacific abstractthe interaction of recurving tropical cyclones tcs with midlatitude rossby waves during extratropical transition et can significantly alter the midlatitude flow configuration this study provides a climatological investigation of rossby wave initiation rwi by transitioning tcs in the specific configuration of an initially zonal midlatitude waveguide and elucidates physical processes governing ab initio flow amplification during et recurving tcs interacting with a zonally oriented waveguide in the western north pacific wnp basin from 1979 to 2013 are categorized into cases initiating rossby waves tc rwi or not tc norwi interactions with a zonally oriented waveguide occurred for 22 7 of the recurving tcs and one third of these resulted in tc rwi in the presence of a tc the probability of rwi on a zonally oriented waveguide is 3 times larger than in situations without a tc the occurrence of tc rwi exhibits a seasonality and is relatively more common during boreal summer than in aut

controls on the seasonal deformation of slow moving landslides article history precipitation drives seasonal velocity changes in slow moving landslides by increasing pore water pressure and reducing the effective normal stress along basal shear zones this pressure change is often modeled as a pore water pressure wave that diffuses through the landslide body such that the minimum time required for landslides to respond to rainfall should vary as the square of landslide depth which often approximates the saturated thickness and inversely with hydraulic diffusivity here we assess this model with new observations from the landslide prone eel river catchment northern california using satellite radar interferometry insar time series precipitation data and high resolution topographic data from airborne lidar we quantify the seasonal dynamics of 10 slow moving landslides which share the same lithologic tectonic and mediterranean climate conditions these slope failures have areas ranging from 0 16 to 3 1 km 2

piping process genesis and network characterization through a pedological and geophysical approach abstract piping is a soil erosion process initiated by concentrated subsurface water flow which can develop in both natural and anthropogenic landscapes and causes various environmental impacts the piping process acts as a relief modifier leading to soil subsidence on a short time scale this paper aims to provide a more comprehensive characterization of the piping process in a tropical forested area of brazil first we sought to understand and examine the subsurface environment of the soil using field description and soil sampling for chemical and physical analyses ph cec bulk density total porosity flocculation degree based on this information we performed geophysical tests using direct current resistivity method dc resistivity with six lines of electrical resistivity tomography ert to map the pipes and check the connection between subsurface tunnels data on the basic properties of the soil aided our interpretation of the geophysical results and the genesis of the piping process the soil of the study area presented horizons in which textural variations accompanied changes in total porosity bulk density and flocculation degree the dc resistivity method efficiently detected the pipes resistive zones of values 4000 o m and high contrast with adjacent zones and revealed the connection and continuity of the pipe network while various factors may contribute to the subsurface erosive process in the study area the decisive factor triggering the process seems to be the presence of a permeable layer that lies just above the impermeable layer which may stop water infiltration and facilitate the lateral water movement

rainfall induced landslides and debris flows in this preface we introduce the special issue on rainfall induced landslides and debris flows the topic is of high interest for many practical and scientific reasons in fact rainfall is the most relevant factor for the triggering of both shallow and deep seated landslides and rainfall analysis is the most frequently adopted approach for forecasting the occurrence of such phenomena the six papers of the special issue cover most of the key issues relative to rainfall induced landslides starting from the analysis of these contributions we identify and discuss in this paper several main topics that deserve further research in the field of rainfall induced landslide such as the uncertainty of the data the quality of geotechnical analysis the validation of the models and the applicability of results in the framework of natural hazards copyright 2007 john wiley sons ltd

heavy metal geochemistry of surface sediments from the southern black sea shelf and upper slope abstract a wide variety of sediment types mud to sandy gravel was obtained at fourty seven stations on the southern black sea shelf and upper slope and analyzed for their heavy metal geochemistry distribution of grain size carbonates organic carbon and heavy metals show marked changes in the topography biological activity and land geology of the region studied sediments constitued up to 39 caco3 mainly of biogenic origin from the shell remains of benthic organisms organic carbon contents of the sediments 0 13 3 09 usually reflect the prevailing primary productivities in the black sea although significant terrigenous influences are also inferred the heavy metal concentrations largely indicate the influences from the geochemical weathering of terrigenous sources on land in comparison with the average sedimentary rocks and other modern sediments from the adjacent regions the concentrations of cr ni cu zn and pb are somehow higher in the surface sediments from the southern black sea in particular cr ni and cu are found in high abundances in the eastern parts of the study area this is thought to reflect not only the well mixed fine grained nature of the sediments but also the possible contribution from metal rich rocks mafic and ultramafic sources and associated economic mineral deposits in the catchment areas of rivers which drain this part of the coast the presence of significant positive correlations between the concentrations of cr and ni and zn and pb strongly suggest common sources and or similar enrichment mechanisms for these metals the relationships among the geochemical variables revealed that fe and mn oxides hydrates and sulfides and organic phases together with the clay and silt sized grain fractions are the important associations of the studied heavy metals

spatially varying hydraulic and solute transport characteristics of a fractured till determined by field tracer tests funen denmark a natural gradient tracer test that simulated one dimensional flow was conducted in a large 4 m 4 8 m surface area isolated block of fractured till in funen denmark to determine both bulk and spatially distributed hydraulic properties hydraulic conductivity based on free flow tests was higher in the upper 2 5 m 5 81 10 5 m s 1 than in the upper 4 m 8 00 10 6 m s 1 of till indicating the more highly fractured and bioturbated nature of the upper part of the till chloride was introduced at the surface of the block as nacl solution 490 mg l 1 cl and breakthrough of cl was monitored in 13 horizontal screens at depths of 2 5 and 4 m arrival times of half of the input cl concentrations c c0 0 5 ranged about sevenfold among various screens at each sampling depth 5 35 hours at 2 5 m and 11 68 hours at 4 m chloride breakthrough data for the two depths were fitted to both an equivalent porous media epm model based on the convective dispersive equation and a discrete fracture model these results indicate differences in transport characteristics of the till with depth at the 2 5 m depth the epm model fit the initial part of the breakthrough curves quite well for most samplers but did not predict the long tails adequately the converse was generally true for the discrete fracture model thus it appears that transport in the upper 2 5 m of till is controlled by a complex interconnected system of fractures and macropores field measurements of fractures and macropores at this site substantiate these results at the 4 m depth the discrete fracture model described solute transport in all samplers better than the epm model indicating that vertical fracture flow dominates in the lower portion of the block fracture apertures and spacings were estimated based on the cubic law and fitting the breakthrough data to the discrete fracture model fitted fracture spacings at the 4 m depth 0 025 0 08 m were slightly smaller than the minimum spacing 0 09 m mapped in the field calculated apertures at the 4 m depth were large compared with other studies and ranged from 65 to 127 m average value of 94 m

biological energy in landscape evolution traditional conceptual models of landscape evolution view topography as an outcome of endogenic forces uplift working against exogenic forces of denudation the energy considerations of these concepts have focused on the conversion of the potential energy of landscape relief to kinetic energy the concept of the biosphere as a planetary membrane for capturing and converting solar energy coupled with the critical geomorphic role of biota call for a consideration of biotic contributions to geomorphic work a review of estimates of global rates of kinetic energy of denudation and uplift and net primary production npp indicates that the energy density of npp is on average three to seven orders of magnitude greater than the others if even a tiny fraction of npp is geologically significant then the biological subsidy to the energy of landscape evolution must be considered on a par with that of geophysical and geochemical phenomena a case study in eastern kentucky shows that even if only 0 1 percent of npp is geomorphically significant it still far exceeds the energy inputs from uplift and conversion of potential to kinetic energy by denudation this is unlikely to be unique though the relative importance of biological and geophysical processes must obviously vary with climate tectonic setting and other factors results indicate that particularly where biological activity is significant geomorphic work performed by biota may be greater than that associated with endogenic processes and with the kinetic energy of denudation

impact of soil characteristics on piping activity in a mountainous area under a temperate climate bieszczady mts eastern carpathians abstract this paper aims at a better understanding of the role of soil characteristics in piping activity in a mountainous area under a temperate climate the recognition of favourable soil properties is widely described in badlands with dispersive materials and in loess covered hilly regions in other regions without dispersive materials or without extensive loess deposits piping conditions draw hardly any attention the survey was carried out in the tyskowa catchment in the bieszczady mts eastern carpathians we focused on soil characteristics that can impact erodibility including texture structure consistence porosity and bulk density these characteristics as well as selected chemical properties ph exchangeable cations and sodium absorption ratio sar were studied in detail for 4 soil profiles with a different position in relation to collapsed pipes cps on a slope with abundant cps and on one lacking cps we tested a hypothesis that soil properties control the occurrence of pipes and we checked if there is any difference in soil properties on slopes with and without cps moreover we compared soil profiles within the slope with cps additionally detailed geomorphological mapping of piping forms was carried out in the selected catchment in order to determine the depth of the pipe formation no clear difference in soil characteristics was observed between the slope with high piping activity and the one without it with cambisols occupying both sites the soils exhibit a large content of silt which potentially enhances piping the chemical properties do not differ among the analysed soils however the profiles at the site above cps with potential piping and in the sinkhole are characterized by intense biological activity the development of soil structure in deeper horizons angular and subangular blocky structure down to 90 105 cm high porosity and low bulk density to summarize it is the combination of biological activity and soil properties silty texture well developed soil structure low bulk density and high porosity that determines the formation of pipes in the study area combining all the results from the soil profiles and the depth of pipes indicates that pipes develop on the boundary of b and c soil horizons and the mean depth of pipe formation is almost 0 80 m with the maximum of 1 55 m

a comparison of the downstream predictability associated with et and baroclinic cyclones abstractthe impact of the extratropical transition et of tropical cyclones and baroclinic cyclogenesis in the western north pacific wnp atlantic and southern indian ocean sio basins on the predictability of the downstream midlatitude flow is assessed using 30 years of cases from the global ensemble forecast system gefs reforecast version 2 in all three basins et is associated with statistically larger 500 hpa geopotential height forecast standard deviation sd compared to the forecast climatology the higher sd values originate from where the tc enters the midlatitudes and spread downstream at the group velocity of the associated wave packet of the three basins wnp et is associated with the largest amplitude and longest lasting sd anomalies forecasts initialized 2 4 days prior to the onset of et have larger sd anomalies compared to forecasts initialized during or after the onset of et by contrast the region of positive sd anomaly associated with winter baroclinic cyclones is confined to

contaminant migration through fractured till into an underlying aquifer this paper examines the potential impact on groundwater quality of contaminant migration from a landfill site through a fractured till and into an underlying aquifer the paper describes a simple semi analytic technique for modelling contaminant transport through the fractured till including consideration of diffusion of contaminants from the fractures into the till matrix sorption and radioactive decay the model also considers the finite mass of contaminant and dilution due to the flow of groundwater in the aquifer the model can be readily implemented on a microcomputer the model allows examination of variations in fracture spacing fracture opening size thickness of the fractured zone diffusion coefficient dispersivity effective porosity of the matrix radioactive decay darcy velocity thickness of the aquifer distribution coefficient and mass of contaminant the paper describes the results of a limited parametric study that inter alia examines the effects of uncertainty in fracture sp

two methods for the tracing of pipe flow on hillslopes abstract two techniques for the determination of soil pipe networks on hillslopes which avoid the logistic difficulties associated with the unpredictable and ephemeral nature of pipe flow are described passive detectors of activated charcoal in conjunction with fluorescent dyes proved to be most useful for the general definition of networks over moderate areas whereas artificial injections of water permitted much more detailed information to be obtained the networks comprised anastomosing bands with definite tributary and distributary zones the gross network form was stable over a five year period but the function of individual links could change even during a storm event velocities of pipe flow were comparable with those of overland flow in the area and very much faster than observed rates of throughflow a complex interrelation between these three flow processes was observed during the experiments

application of image based granulometry to siliceous and calcareous estuarine and marine sediments abstract grain size analysis has long been used as a descriptor of transport and depositional processes this paper presents the possibility of using image based granulometries not yet widely used in the earth sciences to characterize granulometric composition of unconsolidated estuarine and marine sediments to test the method conventional sediment analysis of siliceous and calcareous sediments are compared to image based analysis of sediments obtained along the ore estuary northern sweden and the adriatic sea croatia and italy these grains have different textural characteristics composition roundness and specific surface area granulometric parameters are calculated using both a graphical method and the mathematical method of moments grains have been imaged using a microscope and mathematical granulometries have been applied to the digital data image based granulometric moment descriptors are compared with sieve coulter counter derived moments although it is not claimed that digital imaging should be the only method used in sedimentology the results show the potential of applying digital electronic imaging to granulometric analysis of sediments in this way sampling for granulometric analysis and sieving processes combined with coulter counter analysis of fraction