groundwater controls on biogeomorphic succession and river channel morphodynamics biogeomorphic succession describes feedbacks between vegetation succession and fluvial processes that at the decadal timescale lead to a transition from bare river deposited sediment to fully developed riparian forest where the rate of stabilization by biogeomorphic succession is greater than the rate of ecological disturbance by fluvial processes a river is likely to evolve into less dynamic states while river research has frequently considered the physical dimensions of morphodynamics less is known about physical controls on succession rates and how these impact stream morphodynamics here we test the hypothesis that groundwater dynamics influence morphodynamics via the rate of biogeomorphic succession we applied historic imagery analysis in combination with dendroecological methods for willows growing on young gravelly fluvial landforms along a steep groundwater depth gradient we determined the following floodplain morphodynamics and plant encroachment at the decadal scale pioneer willow growth rates and their relationships to hydrological variables willow growth rates were correlated with moisture availability groundwater discharge and precipitation variability in the downwelling reach while little correlation was found in the upwelling reach after a reduction in ecological disturbance frequency data suggest that where groundwater is upwelling biogeomorphic succession is fast the engineering effect of vegetation is quickly established and hence channel stability increased and active channel width reduces where groundwater is downwelling deeper and more variable biogeomorphic succession is slower the engineering effect is reduced and a wider active width is maintained thus groundwater is an important control on biogeomorphic feedbacks intensity and through the stabilizing effect of vegetation may drive long term river channel morphodynamics

composite model with fractional flow dimensions for well test analysis in fractured rocks abstract the represented analytical model is addressed to fracture zone aquifers in which well test responses can be commonly matched with models involving fractional flow dimensions the model assumes a composite structure representing the fractures opening into the pumping well and the fracture system comprising the actual aquifer the aim is to assess the hydraulic properties for the near well zone and the aquifer in terms of concrete parameters even if flow dimensions have fractional values dimensionless drawdown in pumping and observation wells was solved by applying laplace transforms the early time approximation for the pumping well can be used to assess the transmissivity t 1 if the flow dimension in the inner zone n 1 is greater than about 1 7 the long time solutions indicate that the inner zone induces a pseudo skin effect that can be estimated by comparing the pumping well and observation well data if k 1 is known the extent of the inner zone r can be estimated from the pseudo skin factor the responses tend to form log log straight lines with slopes of 1 n 2 by plotting drawdown vs t 1 n 2 on the double logarithmic scale the product of the hydraulic conductivity and the through flow area at the wellbore radius ka 2 and the hydraulic diffusivity d 2 of the aquifer can be estimated from the slope and the intercept the hydraulic conductivity of the aquifer k 2 is estimated by considering the through flow area as a projection of an n 2 dimensional sphere with a radius of r wb through three dimensional space by an amount r 3 n 2 the analyzed field example comprises a pumping test of a fracture zone aquifer in south central finland for the pumping well simultaneous matching of drawdown and derivative type curves with observed responses can be used to verify the results of the early time analysis and the proposed straight line procedure in addition type curve matching yields estimates of the hydraulic diffusivity ratio and a value of the dimensionless wellbore storage the analyzed observation wells are considered to be sufficiently far from the inner zone consequently type curves are produced based on the dimensionless drawdown solution that is identical to generalized radial flow model type curve matching of the observation well responses produces estimates for ka 2 k 2 and d 2 the obtained values are similar to previous studies that included models relying on integer flow dimensions however models relying on the fractional flow dimensions are capable to simulate the observed responses more accurately

the use of velocity and conductivity data for the quantification of heterogeneity a comparison hydraulic conductivities of a portion of the twin lake aquifer are derived from grain size analyses performed at 3 cm vertical sampling intervals in four boreholes spaced l m apart correlation of conductivity logs between four boreholes leads to a geometrical model which corresponds closely to the spatial structure derived from the velocity field of previous tracer tests histogram and correlogram analyses of conductivities agree closely with those of velocities and the two data sets appear equally useful for characterizing the aquifer and its spatial variability using darcy s law flow velocities and conductivities are combined to calculate a theoretical hydraulic gradient comparison to gradients observed at the site reveals agreement on a large scale however differences exist in detail because observed piezometric heads fail to reflect small scale heterogeneity since these differences are significant for contaminant transport prediction it is recommended for future studies to directly measure flow velocities from a tracer experiment rather than to reply on head measurements and on darcy s law for the calculation of transport parameters

morphological adaptation of river channels to vegetation establishment a laboratory study while the scientific community has long recognized that alluvial rivers are the product of interactions between flowing water and bed material transport it is increasingly evident that vegetation mediates these interactions and influences the stream channel characteristics in a novel set of mobile bed laboratory experiments with variable discharge we demonstrate that vegetation colonization affects bank erosion rates channel shape channel sinuosity and bar pattern our analyses compared the morphological evolution of channels with initially steady bars considering the following three scenarios 1 channel without vegetation 2 channel with vegetation added to the floodplains and 3 channel with vegetation added to both the floodplains and the bar surfaces that emerge at low flows absence of vegetation produced the widest and shallowest channel with the lowest sinuosity floodplain vegetation in the second scenario reduced bank erosion and resulted in a deeper and more sinuous channel with shorter bars in the third scenario vegetation establishment on emerging bar surfaces intensified erosion on the opposing bank enlarging the amplitude of bends enhanced sedimentation on vegetated bar areas increased both bar elevation and bar length compared to the second scenario the results show that the colonization of bar surfaces by plants creates the conditions for new floodplain and island formation fostering channel meandering and anabranching finally our experiments emphasize the role of alternating high and low flows on the morphological development of streams mediated by vegetation

characterization of aquifer heterogeneity by in situ sensing in analyzing groundwater flow and mass transport most commonly the heterogeneity of a geologic formation is quantified by the field mapping of the hydraulic conductivity distribution in this paper two alternative approaches are proposed according to the first nonparametric approach aquifer heterogeneity is characterized in terms of spatial variability in the concentration field generated in a natural gradient tracer test with a high energy gamma emitting radiotracer in situ sensing technology is used for mapping the concentration distribution and collected concentration versus depth profiles are correlated to produce the local scale geometric model of aquifer heterogeneities for further numerical groundwater flow and mass transport modeling in the second parametric approach heterogeneity is characterized in terms of spatial variability of the groundwater velocity rather than in terms of spatial variability of the hydraulic conductivity geostatistics is used to characterize the local scale velocity variation in terms of velocity integral scales in three orthogonal directions in the longitudinal along the mean flow and two transverse across the flow directions the velocity correlation volume is estimated as 16 68 2 0 22 m it defines the characteristic volume for the field scale groundwater flow and mass transport modeling it was concluded that the field mapping of aquifer structure by measuring concentrations and travel times of a radiotracer leads to a fundamentally new approach to the characterization of geologic heterogeneity and offers a reliable means for solving this complex problem of contemporary hydrogeology in quantitative terms

numerical modeling on flow of groundwater energies in transient well capture zones capture zone delineation is indispensable in all wellhead protection programs for the safeguarding of groundwater supplies transients in the flow model tend to influence the capture zone geometry over time thus transient analyses of well capture zones are superior to the steady state analogs for all practical cases with time varying flow parameters energy gradients drive groundwater flow like any other natural phenomena along with the evolving capture zone energy transformations within the model domain were also therefore assessed to portray the state of the system with time the energy components in the form of frictional dissipation and change in internal energy were estimated at all time steps beside delineating the capture zones this paper numerically models a two dimensional homogeneous isotropic confined aquifer and thereby delineating the capture zones by subsequent examination of the energies within the energy approach facilitated the identification of areas having pronounced transient behavior compared to the entire region within the capture zone and model domain the current study reveals that there was an unusual increase in the internal energy term for two time periods of the entire cycle investigated and highlighted the compressibility effects of the system this has been correlated to the change in the distribution of capture fraction values within the capture zones of those specific time periods

a general geomorphological recession flow model for river basins 1 recession flows in a basin are controlled by the temporal evolution of its active drainage network adn the geomorphological recession flow model grfm assumes that both the rate of flow generation per unit adn length q and the speed at which adn heads move downstream c remain constant during a recession event thereby it connects the power law exponent of dq dt versus q discharge at the outlet at time t curve with the structure of the drainage network a fixed entity in this study we first reformulate the grfm for horton strahler networks and show that the geomorphic g is equal to d d 1 where d is the fractal dimension of the drainage network we then propose a more general recession flow model by expressing both q and c as functions of horton strahler stream order we show that it is possible to have g for a recession event even when q and c do not remain constant the modified grfm suggests that is controlled by the spatial distribution of subsurface storage within the basin by analyzing streamflow data from 39 u s geological survey basins we show that is having a power law relationship with recession curve peak which indicates that the spatial distribution of subsurface storage varies across recession events

understanding processes of island development on an island braided river over timescales from days to decades this is the peer reviewed version of the following article gurnell a m bertoldi w francis r a gurnell j and mardhiah u 2019 understanding processes of island development on an island braided river over timescales from days to decades earth surf process landforms 44 624 640 https doi org 10 1002 esp 4494 which has been published in final form at https doi org 10 1002 esp 4494 this article may be used for non commercial purposes in accordance with wiley terms and conditions for use of self archived versions

strontium isotope systematics of base flow in piedmont province watersheds georgia usa abstract 87 sr 86 sr ratio variations were analyzed in rainfall shallow ground water and base flow collected from 4 piedmont streams within the middle oconee river basin in northeastern georgia during the period between march 2003 and march 2004 they sr isotope ratio analyses were accompanied by measurements of stream discharge rainfall stable o isotope ratios and major ion and 3 h concentrations the average sr ion concentration and 87 sr 86 sr ratio for the terminal stream basin the middle oconee river were 23 6 g l and 0 7172 respectively the average 87 sr 86 sr ratios of the rainwater and shallow ground water were below 0 7125 indicating that most of the sr in this stream water is input by weathering reactions in deeper ground water rather than by ion exchange in shallow soil horizons this is consistent with the higher alkalinity concentrations 23 47 mg l and specific conductance values 60 113 s cm that characterize stream base flow piedmont streams are characterized by lower concentrations of sr and higher 87 sr 86 sr ratios than average global stream flow base flow rates decreased by a factor of 2 3 during the summer months and this is accompanied by increased alkalinity concentrations 87 sr 86 sr ratios however were temporally invariant for a given stream basin and were independent of season antecedent rainfall and discharge 87 sr 86 sr ratios were unique for each of the 4 basins and a general trend toward higher ratios with increasing basin area was apparent the inferred contribution from minerals with high rb contents such as k feldspar and muscovite may have resulted from the greater integration of flow from mineralogically diverse pathways afforded by a larger basin area the basin specificity and temporal or seasonal invariability make 87 sr 86 sr ratios an invaluable hydrological tracer that can be readily employed in mass balance studies of stream flow within the piedmont province

the recycling of flint throughout the lower and middle paleolithic sequence of tabun cave israel abstract tabun cave provides an opportunity to examine transformations in the methods and intensity at which hominins recycled flint items along a sequence of ca 500 ky from the lower paleolithic to the middle paleolithic periods the studied sequence is composed of results from jelinek s excavations and ronen s excavations which sampled different parts of the stratigraphic section of tabun cave together covering 16 m depth of superimposed archaeological layers the recycling of flint is examined using three aspects 1 the presence of patinated items 2 the phenomenon of handaxes with a preferential flake scar along with other aspects indicating the recycling of handaxes as cores and 3 the presence of items which are both cores on flakes and tools indicating a complex life history the changes in their frequencies and characteristics along the sequence are presented through a study of 20 assemblages spanning from the acheulean lower paleolithic to the early middle paleolithic

numerical simulations of twin lake natural gradient tracer tests a comparison of methods the primary objectives of the twin lake experiments have been to study geologic heterogeneities and field scale dispersion and to provide data for developing and evaluating groundwater flow and transport models the experiment reported here was undertaken in 1987 1988 to expand the studies of heterogeneity and dispersion from a 40 m scale investigated in 1983 to a full 270 m scale from the point of tracer injection to the groundwater discharge zone the hydrogeologic setting the experimental and analytical methods and the interpretation of experimental data are the topics of discussion in this paper the 1983 and 1987 1988 tracer tests were used to evaluate the predictive abilities of various numerical groundwater flow and transport models the modeling is done along the mean flow direction in the vertical plane the two dimensional finite element modeling was successful in simulating the hydraulic head distribution but not the groundwater motion or the tracer transport in addition owing to the advection dominated nature of the groundwater flow the transport simulation suffered from numerical dispersion significant improvements in simulations were obtained using method of characteristics and random walk based computer models the influence of dimensionality on the transport simulation was evaluated by comparing the two and three dimensional random walk simulations it was found that over the first 40 m along the mean flow path the three dimensional simulation does not reproduce the plume migration any better than the two dimensional simulation does random walk simulations of the transport observed in the 1983 and 1987 1988 tests are also done on the basis of the advection dispersion equation and tracer test derived velocities without invoking the concept of hydraulic conductivity and darcy s law these simulations were found to be superior to simulations based on the coupled flow and transport models it was also found that the simulated hydraulic head distribution is insensitive to spatial variations in hydraulic conductivity and the simulated groundwater velocity distribution is inappropriate for transport modeling it was concluded that the advection dispersion models of the local scale transport perform better in predicting the tracer migration at the twin lake aquifer using measured velocities rather than velocities simulated by a flow model

cross borehole slug test analysis in a fractured limestone aquifer summary this work proposes new semi analytical solutions for the interpretation of cross borehole slug tests in fractured media our model is an extension of a previous work by barker barker j a 1988 a generalized radial flow model for hydraulic tests in fractured rock water resources research 24 10 1796 1804 butler jr j j zhan x 2004 hydraulic tests in highly permeable aquifers water resources research 40 w12402 doi 10 1029 2003 wr002998 it includes inertial effects at both test and observation wells and a fractional flow dimension in the aquifer the model has five fitting parameters flow dimension n hydraulic conductivity k specific storage coefficient ss and effective lengths of test well le and of observation well leo the results of a sensitivity analysis show that the most sensitive parameter is the flow dimension n the model sensitivity to other parameters may be ranked as follows k le leo ss the sensitivity to aquifer storage remains one or two orders of magnitude lower than that to other parameters the model has been coupled to an automatic inversion algorithm for facilitating the interpretation of real field data this inversion algorithm is based on a gauss newton optimization procedure conditioned by re scaled sensitivities it has been used to interpret successfully cross borehole slug test data from the hydrogeological experimental site hes of poitiers france consisting of fractured and karstic limestones hes data provide flow dimension values ranging between 1 6 and 2 5 and hydraulic conductivity values ranging between 4 4 10 5 and 7 7 10 4 m s 1 these values are consistent with previous interpretations of single well slug tests the results of the sensitivity analysis are confirmed by calculations of relative errors on parameter estimates which show that accuracy on n and k is below 20 and that on ss is about one order of magnitude the k values interpreted from cross borehole slug tests are one order of magnitude higher than those previously interpreted from interference pumping tests these findings suggest that cross borehole slug tests focus on preferential flowpath networks made by fractures and karstic channels i e the head perturbation induced by a slug test propagates only through those flowpaths with the lowest hydraulic resistance as a result cross borehole slug tests are expected to identify the hydrodynamic properties of karstic channels and fracture flowpaths and may be considered as complementary to pumping tests which more likely provide bulk properties of the whole fracture karstic channel matrix system

numerical delineation of transient capture zones delineating capture zones plays an important role in the protection of drinking water wells in the recent literature most of the related work has dealt with the uncertainty of location and extent of the capture zone due to the heterogeneity of the hydrogeologic parameters of the aquifer this paper is about the impact of considering transient aquifer conditions when computing the capture zone of a well the presented approach alternates for predefined time steps between the groundwater flow and a particle tracking module enabling the management of a vast number of individual particles thus the development of the capture zone can be monitored more precisely and it can be differentiated between parts of it specific results are presented for an aquifer in south east austria in terms of the percentage of particles of any starting location that are terminated by a well and of the minimum travel time a particle needs from the same starting location to reach a well the transient delineated capture zone is compared to those derived from steady state computations for specific groundwater flow conditions though the results are site specific the significance of considering the transient system boundary conditions is demonstrated since a superposition of the steady state case results clearly overestimates the area to be protected additionally in order to address sensitivity and computational efficiency the effect of increasing the release interval and the starting pattern of particles on the development of the capture zone is analyzed

estimation of discharge from three braided rivers using synthetic aperture radar satellite imagery potential application to ungaged basins analysis of 41 ers 1 synthetic aperture radar images and simultaneous ground measurements of discharge for three large braided rivers indicates that the area of active flow on braided river floodplains is primarily a function of discharge a power law correlation is found between satellite derived effective width we and discharge q where we is the water surface area within a braided reach divided by the reach length synthetic values of we and q generated from a cellular automata model of stream braiding display a similar power law correlation power functions that are fit through plots of we and q represent satellite derived rating curves that can subsequently be used to estimate instantaneous river discharge from space with errors ranging from tens to hundreds of cubic meters per second for ungaged rivers changes in relative discharge can be determined from satellite data alone to determine the shape and timing of annual flows in glacierized basins absolute discharge can probably be estimated within a factor of 2 more accurate estimates will require either 1 one or more ground measurements of discharge acquired simultaneously with a satellite image acquisition or 2 successful parameterization of known morphologic controls such as total sinuosity 5 p valley slope bank material and stability and braid channel hydraulic geometry values of total sinuosity 5 p derived from satellite imagery and field measurements from two rivers of braid channel width depth velocity water surface slope and bed material grain size indicate that while the shape of satellite derived we q rating curves may be influenced by all of these variables the sensitivity of flow area to changing discharge is most dependent upon the degree of braiding efforts to monitor river discharge from space will be most successful for intensely braided rivers with high values of total sinuosity subsampling of existing daily discharge records from the iskut river suggests that satellite return times of about 1 week are sufficient for approximating the shape and timing of the seasonal hydrograph in large glacierized basins although errors are large the presented technique represents the only currently available way to estimate discharge in ungauged braided rivers

structural analysis of supracrustal faults in the charlevoix area quebec relation to impact cratering and the st laurent fault system the charlevoix area which is host to an impact structure of devonian age straddles the boundaries among crystalline rocks of the grenville province the cambrian ordovician sedimentary succession of the st lawrence platform and accreted units of the appalachian orogen the area features well developed supracrustal fault systems attributed to impact cratering a major fault system oriented from northeast to northwest consists of normal faults marked by cataclastic and gouge breccias and less frequently by pseudotachylyte detailed mapping of faults both within and outside the charlevoix impact crater suggests that brittle faulting occurred both before and after impact cratering polymictic fault breccias occurring along some supracrustal faults are the clearest evidence of impact related fault rocks in the charlevoix area the st laurent fault trending to the northeast represents a major structure interpreted as being related to late proterozoic early paleozoic rifting of the iapetus ocean howev

a conceptual hydrodynamic model of a geological discontinuity in hard rock aquifers example of a quartz reef in granitic terrain in south india summary the structure and hydrodynamic properties of geological discontinuities and of a deeply weathered granite aquifer near these structures are described on the basis of geological geophysical and hydrodynamic investigations in two sites of south india located along a 20 40 m wide quartz reef intruding a weathered archean biotite granite one of the two sites also comprises a metre wide dolerite dyke weathering processes appear to be at the origin of fissures development and of a related enhanced local hydraulic conductivity both in the quartz reef and in the surrounding granite the weathering profile in the granite saprolite and fissured layer is characterized by an abrupt deepening of the weathered layers in the granite near the contact and in the quartz reef itself therefore the weathering profile shows a u shape geometry with among others the verticalization of the granite s fissured layer the hydraulic conductivity of this verticalized layer is on average 5 10 6 m s and storativity about 10 3 the hydraulic conductivity of the fissured quartz is 4 6 10 6 m s and its storativity about 3 5 10 4 both media are also characterized by a matrix hydraulic conductivity 10 7 10 9 m s and by a significant heterogeneity in hydrodynamic properties that generates preferential flow paths along the sub vertical fissures parallel to the reef axis a special attention has been paid for characterizing this heterogeneity the weathering of the dolerite dyke however results in a local low hydraulic conductivity which consequently does not enhance either the thickness of weathered granite layers or its hydraulic conductivity the obtained results complete the conceptual hydrogeological model developed for weathered granite aquifers in characterizing the relationships between weathering processes and hydrodynamic properties near geological discontinuities

flow bearing structures of fractured rocks insights from hydraulic property scalings revealed by a pumping test abstract a long duration pumping test conducted over 151 days in a fractured sandstone and shale formation displays a nonstandard drawdown response and anomalous pressure diffusion which cannot be properly interpreted using existing frameworks e g homogeneous double porosity boundary conditions and fractal models an alternative framework with simple geometry and more complex hydraulic properties is thus proposed to interpret such kind of drawdown responses the analytical development allows first to demonstrate all scaling relations in this interpretation framework then and most importantly the multi scale hydraulic test provides consistent scalings of transmissivity t to storativity s over distances ranging from 83 to 383 m in a faulted area drawdown analysis in several monitoring wells shows persistent decrease of transmissivity in highly channelized fracture flow structures in one structure the cubic dependency of transmissivity to storativity identifies a well defined fault and also demonstrates the validity of poiseuille flow at a scale rarely investigated in the other structure the linear dependency of transmissivity to storativity indicates that the flow bearing structure is the surrounding fracture network well designed pumping tests combined with scaling analysis driven by geological evidence thus provide essential information on flow bearing structures for site characterization and modeling tasks at least for moderate to low permeable fractured rocks the scaling of transmissivity to storativity appears to be more informative than any separate interpretation of hydraulic property scaling exponents

uncertainty in wellhead protection area delineation due to uncertainty in aquifer parameter values abstract the importance of modeling in hydrogeologic investigations has been stressed in a number of studies since the applicability of any model is dependent on the type of need and availability of hydrogeological information a parametric analysis is essential to determine its applicability this paper presents the results of a parametric analysis conducted to evaluate the effect of data uncertainty on wellhead protection area whpa delineation the precision of aquifer parameter values is the most important factor in a whpa delineation process in relation to the model itself to demonstrate the effect of variable values in a wellfield we tested modified version of time related analytical groundwater flow concept using a ressqc model which is used for capture zone delineation and to delineate contaminant front for injection wells the ressqc model is a modified version of the ressq code which was initially designed to only delineate contaminant fronts for injection wells field measured aquifer parameters for a shallow aquifer were used in the analysis the results indicate that great caution must be taken when aquifer parameters such as hydraulic gradient thickness transmissivity and porosity are being used for whpa delineation since over or under protection of whpa can jeopardize the public health an extended aquifer test and installation of various observation wells in or near different lithologic and depth zones may increase reliability of parameter values

analysis of the scale dependence of the hydraulic conductivity in complex fractured media abstract fractured geological media are complex systems where hydrodynamic parameters are highly variable as result of their structure indeed measured parameters depend on the scale and the implemented methodologies with high variability of hydrodynamic parameters this variableness also depends on the scale of measurement most theoretical frameworks assume homogeneous media adding uncertainty to the fractured media hydrogeological characterization in fractured media the complexity is even harder to characterize as available theoretical frameworks assume homogeneous media nevertheless the increase of underground engineering projects and their reported impacts on surface and groundwater resources claim efforts to a better understanding of fractured media groundwater hydrodynamics in this work we propose a general approach for the scale dependence of the hydraulic conductivity based on power law concepts to do so the hydraulic conductivity field of a highly fractured massif in the colombian andes is estimated over scales from 6 cm to 12 km laboratory measurements re analyzes of hydraulic tests and calibration of 3d numerical models were performed using the la linea tunnels in colombia as real scale laboratory hydraulic conductivity values vary up to four orders of magnitude at each characteristic length scale and show an increase until the local scale followed by a small decrease at regional scale in this way field and regional scales display the same orders of magnitude finally the scale dependence of the hydraulic conductivity values based on power law concepts is proposed as a consequence it suggests the possibility to use field data in regional models once hydrogeological units and structures are properly defined

insights on pumping well interpretation from flow dimension analysis the learnings of a multi context field database abstract the flow dimension parameter n derived from the generalized radial flow model is a valuable tool to investigate the actual flow regimes that really occur during a pumping test rather than suppose them to be radial as postulated by the theis derived models a numerical approach has shown that when the flow dimension is not radial using the derivative analysis rather than the conventional theis and cooper jacob methods helps to estimate much more accurately the hydraulic conductivity of the aquifer although n has been analysed in numerous studies including field based studies there is a striking lack of knowledge about its occurrence in nature and how it may be related to the hydrogeological setting this study provides an overview of the occurrence of n in natural aquifers located in various geological contexts including crystalline rock carbonate rock and granular aquifers a comprehensive database is compiled from governmental and industrial sources based on 69 constant rate pumping tests by means of a sequential analysis approach we systematically performed a flow dimension analysis in which straight segments on drawdown log derivative time series are interpreted as successive specific and independent flow regimes to reduce the uncertainties inherent in the identification of n sequences we used the proprietary siren code to execute a dual simultaneous fit on both the drawdown and the drawdown log derivative signals using the stated database we investigate the frequency with which the radial and non radial flow regimes occur in fractured rock and granular aquifers and also provide outcomes that indicate the lack of applicability of theis derived models in representing nature the results also emphasize the complexity of hydraulic signatures observed in nature by pointing out n sequential signals and non integer n values that are frequently observed in the database

groundwater flow patterns in extensive shallow aquifers with gentle relief theory and application to the galena locust grove region of eastern maryland 1 the delmarva peninsula between the chesapeake bay and the atlantic ocean comprises an irregular sequence of almost horizontal sand and silt or clay layers shedlock et al 1999 bohlke and denver 1995 whose connectivity and detailed geometry are not well known a mosaic of groundwater basins with areas generally less than 30 km2 provide the water supply for the region the concentration of dissolved nitrate has increased greatly since 1950 shedlock et al 1999 and a series of test wells drilled in the locust grove area for chemical analyses of the groundwater provide useful data on water table levels at various locations a new depth integrated hydraulic model of the aquifer flow is developed to handle the complex and poorly known structure of the region it requires as inputs 1 historical rainfall data 2 the elevation profiles along potential discharge streambeds and 3 the depth integrated hydraulic conductivity inferred from a few individual well water levels the analysis predicts quantitatively and without arbitrary parameters the distribution of groundwater heights above mean sea level and the patterns of total groundwater flow throughout the study region throughout the test area the predicted and measured groundwater levels generally agree to within 1 meter the groundwater flow patterns show two distinctive types of domain with little intermingling one type originating near the groundwater divide and discharging into the semipermanent streams and the other kind arising between the lower stream sections and discharging directly along the estuary shoreline the measured distribution of water age with depth bohlke and denver 1995 agrees well with a simple formula provided by the theory

simulation of groundwater flow in a crystalline rock aquifer system in southern ghana an evaluation of the effects of increased groundwater abstraction on the aquifers using a transient groundwater flow model monitored groundwater level data well logs and aquifer data as well as the relevant surface hydrological data were used to conceptualise the hydrogeological system of the densu basin in southern ghana the objective was to numerically derive the hydraulic conductivity field for better characterization of the aquifer system and for simulating the effects of increasing groundwater abstraction on the aquifer system in the basin the hydraulic conductivity field has been generated in this study through model calibration this study finds that hydraulic conductivity ranges between a low of 2 m d in the middle sections of the basin and about 40 m d in the south clear differences in the underlying geology have been indicated in the distribution of aquifer hydraulic conductivities this is in consonance with the general assertion that the hydrogeological properties of the aquifers in the crystalline basement terrains are controlled by the degree of fracturing and or weathering of the country rock the transient model suggest aquifer specific storage values to range between 6 0 10 5 m 1 and 2 1 10 4 m 1 which are within acceptable range of values normally quoted for similar lithologies in the literature there is an apparent subtle decrease in groundwater recharge from about 13 of the annual precipitation in 2005 to about 10 3 of the precipitation in 2008 the transient model was used to simulate responses of the system to annual increment of groundwater abstraction by 20 at the 2008 recharge rates for the period 2009 2024 the results suggest that the system will not be able to sustain this level of abstraction as it would lead to a basin wide drawdown in the hydraulic head by 4 m by the end of the prediction period it further suggests a safe annual increment in groundwater abstraction by 5 under business as usual recharge conditions identification and protection of groundwater recharge areas in the basin are recommended in order to safeguard the integrity of the resource under the scenario of increased abstraction for commercial activities in the basin copyright 2012 john wiley sons ltd

modeling high sinuosity meanders in a small flume meandering channels with exposed point bars and sinuosities near 2 0 can spontaneously develop in a mix of diatomaceous earth and kaolinite clay the experimental streams that were studied were as small as 4 cm wide they showed many of the characteristics found in large meandering streams such as migration of channels formation of point bars clay plugs chutes and bar scrolls most of the meander series began as a first sharp bend that induced subsequent bends down stream sediment transport specifically bed load together with the slope of the floodplain were the dominant influences if not the cause of the channel instabilities that led to channel migration and bend formation bank cohesion allowed migrating channels to assume sinuous shapes and to maintain fairly uniform widths the experiments were conducted in a small flume and used simple equipment the use of light fine grained materials in flume experiments may prove to be valuable in learning more about the conditions of soil slope and flow which produce various meandering planforms

stability analysis of ecomorphodynamic equations in order to shed light on the influence of riverbed vegetation on river morphodynamics we perform a linear stability analysis on a minimal model of vegetation dynamics coupled with classical one and two dimensional saint venant exner equations of morphodynamics vegetation is modeled as a density field of rigid nonsubmerged cylinders and affects flow via a roughness change furthermore vegetation is assumed to develop following a logistic dependence and may be uprooted by flow first we perform the stability analysis of the reduced one dimensional framework as a result of the competitive interaction between vegetation growth and removal through uprooting we find a domain in the parameter space where originally straight rivers are unstable toward periodic longitudinal patterns for realistic values of the sediment transport parameter the dominant longitudinal wavelength is determined by the parameters of the vegetation model bed topography is found to adjust to the spatial pattern fixed by vegetation subsequently the stability analysis is repeated for the two dimensional framework where the system may evolve toward alternate or multiple bars on a fixed bed we find instability toward alternate bars due to flow vegetation interaction but no multiple bars both alternate and multiple bars are present on a movable vegetated bed finally we find that the addition of vegetation to a previously unvegetated riverbed favors instability toward alternate bars and thus the development of a single course rather than braiding

well catchments and time of travel zones in aquifers with recharge the classical analytical method used to map catchments and time of travel zones of pumping wells was originally derived for another purpose and takes no account of recharge bear and jacobs 1965 generalized catchment shapes are presented here for aquifers with recharge they can be scaled to field situations through two or three nondimensional parameters a semianalytical path line tracing model was used to generate the shapes it contains new expressions for pore water velocities in two infinite strip recharged aquifers one with two fixed head boundaries the other with one impermeable boundary the resulting catchments differ significantly in both shape and size from catchments estimated by the no recharge method generalized results are also presented for time of travel zones which are noticeably smaller than those calculated by the no recharge method comparison with an equivalent recently released model from the u s environmental protection agency shows the latter to give poor estimates of catchments and time of travel zones

parametric transitions between bare and vegetated states in water driven patterns conditions for vegetation spreading and pattern formation are mathematically framed through an analysis encompassing three fundamental processes flow stochasticity vegetation dynamics and sediment transport flow unsteadiness is included through poisson stochastic processes whereby vegetation dynamics appears as a secondary instability which is addressed by floquet theory results show that the model captures the physical conditions heralding the transition between bare and vegetated fluvial states where the nonlinear formation and growth of finite alternate bars are accounted for by center manifold projection this paves the way to understand changes in biogeomorphological styles induced by man in the anthropocene and of natural origin since the paleozoic devonian plant hypothesis

groundwater flow modeling and particle tracking for chemical transport in the southern voltaian aquifers groundwater is the major source of water supply for most uses in the rural settlements in ghana a groundwater flow model was calibrated for some aquifers of the southern voltaian sedimentary system under steady state conditions the objective was to determine estimates of the hydraulic conductivities of the different hydrostratigraphic units of the southern voltaian and the distribution of recharge from precipitation data on the stable isotopes of oxygen and hydrogen from the study area suggest that groundwater recharge in the area is from rainfall the calibrated steady state model suggests that aquifer hydraulic conductivities in the study area range from 1 19 to 6 3 m day hydrostratigraphic unit specific hydraulic conductivities are discussed the calibrated recharge ranges from 3 81e 05 m day to 6 0e 04 m day which represents 0 9 6 of the precipitation in the form of rainfall six distinct flowpaths have been defined using particle tracking the particle tracking simulation suggests travel times in the range of 380 to 5 199 years from recharge areas to discharge areas along the flowpaths identified a contaminant dropped at the recharge areas in the central sections of the model area would travel at these rates along the flowpaths assuming that advection is the dominant transport process inverse geochemical modeling indicates the dissolution of albite k feldspars and anorthite respectively along flowpaths i and iv the inverse modeling along flowpaths i and iv suggest the dissolution of albite k feldspar and anorthite respectively at 1 085e 06 3 16e 08 and 3 168e 07 mmol year

flow behavior in a dual fracture network a model that incorporates a pseudo random process controlled by mechanical rules of fracturing is used to generate 3d orthogonal joint networks in tabular stratified aquifers the results presented here assume that two sets of fractures each with different conductivities coexist this is the case in many aquifers or petroleum reservoirs that contain sets of fractures with distinct hydraulic properties related to each direction of fracturing constant rate pump tests from partially penetrating wells are simulated in synthetic networks the transient head response is analyzed using the type curve approach and plots as a function of time of pressure propagation in the synthetic network are shown the hydrodynamic response can result in a pressure transient that is similar to a dual porosity behavior even though such an assumption was not made a priori we show in this paper that this dual porosity like flow behavior is in fact related to the major role of the network connectivity especially around the well and to the aperture contrast between the different families of fractures that especially affects the earlier hydrodynamic response flow characteristics that may be interpreted as a dual porosity flow behavior are thus related to a lateral heterogeneity large fracture or small fault accordingly when a dual porosity model matches well test data the resulting reservoir parameters can be erroneous because of the model assumptions basis that are not necessarily verified finally it is shown both on simulated data and well test data that such confusion in the interpretation of the flow behavior can easily occur well test data from a single well must therefore be used cautiously to assess the flow properties of fractured reservoirs with lateral heterogeneities such as large fractures or small faults

resistance to pull out of chilean riverine species evidence from laboratory experiments abstract vegetation growing in river bars and banks determines the morphological processes in river channels the presence and dynamics of riverine vegetation depend on the magnitude and frequency of floods able to change morphology and uproot plants and on the plant s resistance to pull out a series of pull out experiments were carried out with the objective to determine the resistance of riverine vegetation to be uprooted and its effects on river bed dynamics nine riverine species were used for the experiment seven of them are native from chile and the other two are exotic and invasive in chilean environments a total of 200 specimens were transplanted in a substrate simulating a bar of a gravel bed river and after 7 months they were individually pulled out and the force and time needed to uproot the plant quantified data were analysed by means of generalised linear models glm and linear regressions and force time curves were interpreted and related to the root morphology of the species glm results showed that resistance values were dependent on root and plant physical characteristics and by the factor species among the species studied the three species showing higher resistance values were native while the less resistant was an exotic invasive species the time needed to uproot the individuals did not seem to be influenced by plant parameters nor by the factor species root architecture seemed to have an effect on plant pull out resistance and uprooting rapidity being heart shaped roots the ones that registered higher resistance values despite this when incorporating flow strength on the findings the exotic invasive ones seemed to be some of the more resistant to uprooting the findings of this paper contribute to the better understanding of river vegetational and sedimentary dynamics and are useful for parameterising the modelling of fluvial landscapes evolution and for the design of river restoration projects

a density dependant finite element model for analysis of saltwater intrusion in coastal aquifers summary saltwater intrusion is a serious problem in coastal regions all over the world it is one of the processes that degrade water quality by raising salinity to levels exceeding acceptable drinking water standards it may occur due to human activities and or by natural events over abstraction is considered the main cause of saltwater intrusion moreover climate change and sea level rise speed up saltwater intrusion this paper presents the development and validation of a coupled transient finite element model for simulation of fluid flow and solute transport in saturate and unsaturated soils with application to study saltwater intrusion in coastal aquifers the model includes coupling of water flow air flow heat flow and solute transport furthermore transient density dependent flow is included in the model and the dependency of dispersion on velocity is considered different mechanisms that govern solute transport in porous media including advection diffusion dispersion adsorption chemical reactions and biological degradation are included in the model the governing equation of the solute transport is solved together with three balance equations for water flow air flow and heat transfer the nonlinear system of governing differential equations is solved using the finite element method in the space domain and a finite difference scheme in the time domain the model is validated by application to a standard case study from the literature henry s problem and then applied to predict saltwater intrusion in a coastal aquifer the results of the model predictions are presented and discussed

fragility of a dark gray shale in northeastern jamaica effects and implications of landslip exposure rapid weathering of strong hitherto un weathered shale rocks was fast enough to have been measurable weekly 4 mm depth per week regular early morning rain showers followed by hot dry afternoons caused frequent wet dry cycles which facilitated rapid slaking of the shale other landslips occurred concurrently on the south bank of the wild cane river where the rock beds dip towards lower ground resistance to impacts in the rock fabric was equally low after decades or weeks of exposure it was concluded that the combination of high frequency wet dry cycles on steeply dipping shale beds and rock attitude caused very rapid weathering rapid slaking of the illitic shales could cause high turbidity levels in contiguous aquatic environments building foundations and roads could be rapidly de stabilized even on such freshly exposed apparently consolidated sites

amudian versus yabrudian under the rock shelf a study of two lithic assemblages from qesem cave israel abstract this paper presents new results of a lithic study of two distinct lithic assemblages from the qesem cave shelf area in the northwestern part of the cave one yabrudian and one amudian both older than 300 ka the two assemblages exhibit clear stratigraphic relations the yabrudian being deposited on top of the amudian a detailed techno typological study of the two assemblages n 30 000 artifacts is presented as well as a comparative analysis between them the results indicate that the yabrudian and amudian of the shelf area are part of the same technological system sharing similar techno typological features differences are mainly at the relative frequency level and in the density of the various elements of the assemblages these results suggest that the differences between the assemblages might be related to differences in human activities in the different strata of the shelf area using different tool kits and not to differences in technology or any other cultural conception

handaxe manufacture and re sharpening throughout the lower paleolithic sequence of tabun cave abstract in this paper we assess the evidence for on site manufacture and re sharpening of handaxes in the lower paleolithic layers of tabun cave by examining the ratio of thinning flakes the typical waste of bifacial manufacture to handaxes our study of twenty nine assemblages ranging from the acheulean to the acheulo yabrudian complex combining results from jelinek s and ronen s excavations shows that thinning flakes are scarce throughout the entire sequence results indicate that handaxes were commonly not manufactured or re sharpened in the excavated area and that these activities were most likely conducted outside the site the late lower paleolithic in various parts of eurasia and africa is characterized by high variability in lithic technology which in the case of the levant is best reflected in the acheulo yabrudian complex this study aids our understanding of variability in the levantine late lower paleolithic by adding the concept of segmentation of reduction as an integral part of late lower paleolithic lithic technology significantly in tabun cave the segmentation of reduction that characterizes handaxe manufacture differs from the patterns observed in amudian blade production and yabrudian scraper manufacture which were both regularly conducted on site the extent of variability and flexibility is thus reflected not only in the technologies employed but also in how different reduction sequences were segmented and executed across the landscape suggesting a link between technical knowledge mobility patterns and landscape exploitation

hydrology and hydraulic properties of a bedded evaporite formation the permian salado formation in the delaware basin of new mexico is an extensively studied evaporite deposit because it is the host formation for the waste isolation pilot plant a repository for transuranic wastes geologic and hydrologic studies of the salado conducted since the mid 1970 s have led to the development of a conceptual model of the hydrogeology of the formation that involves far field permeability in anhydrite layers and at least some impure halite layers pure halite layers and some impure halite layers may not possess an interconnected pore network adequate to provide permeability pore pressures are probably very close to lithostatic pressure in the near field around an excavation dilation creep and shear have created and or enhanced permeability and decreased pore pressure whether flow occurs in the far field under natural gradients or only after some threshold gradient is reached is unknown if far field flow does occur mean pore velocities are probably on the order of a meter per hundreds of thousands to tens of millions of years flow dimensions inferred from most hydraulic test responses are subradial which is believed to reflect channeling of flow through fracture networks or portions of fractures that occupy a diminishing proportion of the radially available space or through percolation networks that are not saturated fully interconnected this is probably related to the directional nature of the permeability created or enhanced by excavation effects inferred values of permeability cannot be separated from their associated flow dimensions therefore numerical models of flow and transport should include heterogeneity that is structured to provide the same flow dimensions as are observed in hydraulic tests modeling of the salado formation around the wipp repository should also include coupling between hydraulic properties and the evolving stress field because hydraulic properties change as the stress field changes

estimating transmissivity from single well pumping tests in heterogeneous aquifers although aquifers are naturally heterogeneous the interpretation of pumping tests is commonly performed under the assumption of aquifer homogeneity this yields interpreted hydraulic parameters averaged over a domain of uncertain extent which disguises their relation to the underlying heterogeneity in this study we numerically investigate the sensitivity of the transient drawdown at the pumping well to nonuniform distributions of transmissivity in confined aquifers frechet kernels and their time derivative are used to estimate two spatially averaged transmissivities denoted the equivalent and interpreted transmissivity teq and tin respectively for the case of single well pumping tests interrelating teq and tin is achieved by modeling tin in terms of a distance dependent radially heterogeneous field in weakly heterogeneous aquifers teq approximates tpw the local transmissivity at the pumped well with increasing degree of heterogeneity teq deviates from tpw as pumping propagates tin starts at tpw approaching the spatial geometric mean of transmissivity during late pumping times limits of the proposed spatial weighting functions are investigated by treating the interpreted storativity sest as an indicator for flow connectivity it is shown numerically that the spatial weights for teq and tin agree well to the underlying heterogeneity if sest 1 finally implications for applying the concepts of teq and tin to heterogeneous domains and for real world applications are discussed it is found that time dependent spatial averages of tin agree well with estimates of the interpreted transmissivity from the continuous derivation method

formation of braided river floodplains waimakariri river new zealand floodplains along the braided gravel bed waimakariri river are discontinuous although generally extensive landforms composed predominantly of gravel bars capped with vertically accreted fines in order of importance three mechanisms lead to floodplain formation river bed abandonment by lateral migration of the braid train initiates the formation of the largest floodpiains which usually occur downstream of tributary fans and valley bedrock spurs in the headwater reaches localized river bed aggradation during high magnitude events leads to floodplain formation by producing a surface resistant to erosion by lesser events due to either the coarse nature of the deposit or by its elevation over the river bed or both the least important mechanism initiating floodplain development is localized river or channel incision a six stage model is proposed for the sequential development of floodplains on the waimakariri river from i active river bed ii stabilizing bar iii incipient floodplain iv established floodplain v mature floodplain and to vi terrace two mechanisms lateral migration by the braid train and reactivation of abandoned channels within floodplains operating separately or in combination are responsible for floodplain reworking and their relatively young age 250 years clearly braided rivers can construct substantial areas of well developed floodplain

characterization of the groundwater flow regime and hydrochemistry of groundwater from the buem formation eastern ghana this study demonstrates the application of multivariate statistical methods in definition of groundwater recharge and discharge areas in a sedimentary basin in ghana q mode hierarchical cluster analysis hca was applied to 57 hydrochemical data from the buem formation in the northern part of the volta region in ghana r mode hca and r mode factor analysis were then applied to the same dataset to reveal the processes controlling the hydrochemistry of groundwater from this hydrogeological formation results of both the q and r mode analyses were backed by graphical methods the analyses revealed two major water types differentiated by salinity levels into four spatial groundwater associations the characteristics of the four groundwater types are discussed the recharge areas are characterized by cahco3 low salinity waters which evolve through rock water interactions to nahco3 high salinity waters in the discharge areas this study finds that the hydrochemistry of groundwater from this formation is mainly controlled by the weathering of minerals principally silicates in the aquifer matrix the effects of the chemistry of recharging precipitation are higher in the recharge areas while mineral weathering tends to be severe close to the discharge areas in the groundwater flow regime all the four spatial groundwater associations have low sodium content but salinity levels increase towards the discharge areas such that some of wells in the discharge areas may not be acceptable for irrigation on grounds of high salinities which might affect the osmotic potentials of plants copyright 2011 john wiley sons ltd

stochastic determination of well capture zones a stochastic approach is adopted for characterizing the uncertainty in well capture zones in heterogeneous formations transmissivity is modeled as a random space function and a monte carlo approach is used to infer the probability distribution of the resulting stochastic capture zones through several numerical experiments the influence of the statistical parameters of transmissivity variation on the extent of uncertainty in the location of the capture zone is investigated two aquifer models are considered a fully confined aquifer and a leaky confined aquifer receiving recharge from above a connection is made with previous work on transport theory and the statistical parameters of the capture zone probability distribution are compared with those of a solute concentration plume

the use of the lateral tranchet blow technique at nesher ramla israel a new cultural marker in the levantine middle paleolithic abstract the open air middle paleolithic site at nesher ramla israel dated to the end of marine isotope stage 6 and marine isotope stage 5 is characterized by extensive use of the lateral tranchet blow technique this technique consists of the removal of an elongated thin spall along the retouched edge of the blank in nesher ramla this technique is used for producing a specific tool kit component unifacially retouched tools with a lateral tranchet blow ltb the tools with ltb were systematically produced throughout the 8 m thick middle paleolithic sequence of nesher ramla representing the major typological category in some of the layers together with tools with ltb the assemblages contain large numbers of ltb spalls here we present a detailed techno morphological analysis of the tools and spalls from nesher ramla unit iii one of the richest archaeological layers of the site our results suggest that the goal of the ltb technique at nesher ramla was to manufacture a tool with an edge that is partially retouched and partially sharp i e shaped by ltb the ltb technique employs a long knapping routine including a series of compulsory and optional steps implying non opportunistic behavior although on site use of the ltb technique is attested the fact that these tools were also often introduced to the site as finished objects further emphasizes their importance and suggests that most of them were not produced on site in response to an immediate need for sharp edges this tool type represents a new previously unreported component in the levantine middle paleolithic toolkit a comparison with other archaeological units along the 8 m thick stratigraphy of nesher ramla suggests that the ltb technique was one of the major techniques for manufacturing tools at that site and that the tools with ltb represent a cultural marker for nesher ramla hominins and possibly a new cultural marker in the levantine middle paleolithic according to a comparison of tools shaped by ltb from other geographic and temporal contexts most notably the central european keilmesser the nesher ramla tools with ltb were likely designed and used by right handed hominins in a longitudinal cutting motion

flow and transport in hierarchically fractured rock we construct multiple realizations of hierarchical fracture networks with fractal dimensions between one and two then simulate single well pumping tests and natural gradient tracer tests on them we calculate averages and standard deviations of test results over the multiple realizations and show individual results for selected cases to highlight key features of flow and transport through hierarchically fractured rock these studies are intended to illustrate the range of possible behavior that can be obtained during fracture dominated hydraulic and tracer tests and provide insights into how to interpret field responses the fractal dimension of the fracture network itself is generally larger than the fractal dimension of the flow field arising during a well test the performance measures of the natural gradient tracer tests including the total flow through the fracture network tracer travel time front width and maximum breakthrough concentration can all be correlated to fractal dimension although some of the features observed in the flow and transport behavior within the hierarchically fractured rock have been observed by other authors using non fractal fracture network concepts e g channelized flow with early breakthrough times crossing breakthrough curves others arise directly from the fractal nature of the fracture network in which variability occurs on all scales e g front width and maximum breakthrough concentration that are constant over a wide range of fractal dimensions generally transport simulations show large variability within a given realization and among realizations with the same fractal dimension even in networks whose dimension is close to two this finding is consistent with the large variability in experimental results observed at fractured rock field sites

regional hydrogeology of the silurian and ordovician sedimentary rock underlying niagara falls ontario canada abstract due to concern over the potential for widespread groundwater contamination in the sedimentary rock underlying the niagara falls area this study was done to investigate the hydrogeology of the silurian and ordovician stratigraphy underlying the upper niagara river and the eastern niagara peninsula seven boreholes up to 150 m deep were drilled instrumented with multiple packer casing tested for permeability sampled for inorganic and organic solutes and monitored for hydraulic head to provide data for a conceptual model of regional groundwater flow results show that there are at least three distinct groundwater flow regimes in the bedrock the uppermost regime consists of fracture zones in the guelph and lockport formations within which hydraulic conductivity hydraulic head measurements and geochemical analyses indicate active groundwater circulation primarily discharging towards the niagara gorge and escarpment underlying the lockport formation are an overpressured high hydraulic head regime in the clinton upper cataract lower queenston formation and an underpressured low hydraulic head regime in the lower cataract upper queenston formation in both regimes geochemical analyses and permeability measurements indicate very old and saline groundwater which probably has undergone minimal migration since pre pleistocene time the implication based on the study so far is that potential groundwater contamination below the bottom of the lockport formation is probably not significant in the niagara falls area except adjacent to the niagara gorge where vertical permeability in the lower flow regimes may be enhanced

groundwater flow and capture zone analysis of the central passaic river basin new jersey delineating capture zones of pumping wells is an important part of safe drinking water and well protection programs capture zones or contributing areas of a groundwater extraction well are the parts of the aquifer recharge areas from which the wells draw their water their extent and location depend on the hydrogeologic conditions such as groundwater recharge pumping scenario and the aquifer properties such as hydraulic conductivity porosity heterogeneity of the medium and hydraulic gradient different methods of delineation can be used depending on the complexity of the hydrogeologic conditions in this study a 3 dimensional transient numerical modflow model was developed for the central passaic river basin cprb and used with a modpath particle tracking code to determine 3 dimensional transient capture zones analytically calculated capture zones from previous studies at the site were compared with the new numerically simulated capture zones the study results revealed that the analytical solution was more conservative estimating larger capture zones than the numerical models of all the parameters that can impact the size shape and location of a capture zone the hydraulic conductivity is one of the most critical capture zones tend to be smaller in lower hydraulic conductivity areas

the search for a topographic signature of life landscapes are shaped by the uplift deformation and breakdown of bedrock and the erosion transport and deposition of sediment life is important in all of these processes over short timescales the impact of life is quite apparent rock weathering soil formation and erosion slope stability and river dynamics are directly influenced by biotic processes that mediate chemical reactions dilate soil disrupt the ground surface and add strength with a weave of roots over geologic time biotic effects are less obvious but equally important biota affect climate and climatic conditions dictate the mechanisms and rates of erosion that control topographic evolution apart from the obvious influence of humans does the resulting landscape bear an unmistakable stamp of life the influence of life on topography is a topic that has remained largely unexplored erosion laws that explicitly include biotic effects are needed to explore how intrinsically small scale biotic processes can influence the form of entire landscapes and to determine whether these processes create a distinctive topography

numerical and experimental investigation of flow and scour around a circular pile the flow around a vertical circular pile exposed to a steady current is studied numerically and experimentally the numerical model is a three dimensional model the model validation was achieved against new experimental data which include two component laser doppler anemometry lda flow measurements and the hot film bed shear stress measurements and reported in the present paper and the data of others and a k w turbulence model was used for closure the model does not have a free surface facility and therefore is applicable only to cases where the froude number is small fr 0 0 2 the flow model was used to study the horseshoe vortex and lee wake vortex flow processes around the pile the influence on the horseshoe vortex of three parameters namely the boundary layer thickness the reynolds number and the bed roughness was investigated in the latter investigation the steady solution of the model was chosen a study of the influence of the unsteady solution on the previously mentioned flow processes was also carried out the ranges of the parameters covered in the numerical simulations are the boundary layer thickness to pile diameter ratio is varied from 2 x 10 2 to 10 2 the pile reynolds number from 10 2 to 2 10 6 and the pile diameter to roughness ratio from 2 to about 10 3 the amplification of the bed shear stress around the pile including the areas under the horseshoe vortex and the lee wake region was obtained for various values of the previously mentioned parameters the steady state flow model was coupled with a morphologic model to calculate scour around a vertical circular pile exposed to a steady current in the case of non cohesive sediment the morphologic model includes i a two dimensional bed load sediment transport description and ii a description of surface layer sand slides for bed slopes exceeding the angle of repose the results show that the present numerical simulation captures all the main features of the scour process the equilibrium scour depth obtained from the simulation agrees well with the experiments for the upstream scour hole some discrepancy up to 30 was observed however for the downstream scour hole the calculations show that the amplification of the bed shear stress around the pile in the equilibrium state of the scour process is reduced considerably with respect to that experienced at the initial stage where the bed is plane

interpretation of pumping tests in a mixed flow karst system a long duration pumping test performed in the conduit of a mixed flow karst system mfks is analyzed and interpreted it constitutes a unique experiment of catchment wide response of a karst system with drawdowns measured both in the pumped conduit and in the matrix a modeling approach is proposed for this interpretation the developed double continuum model consists of two reservoirs karst conduits and the surrounding carbonate rocks between which flow exchange is modeled using the superposition principle and the hypothesis of darcian flow in the matrix considered as an equivalent porous media the karst conduits are assumed to have an infinite hydraulic conductivity model calibration results in a very good match relative root mean square rrms 2 3 with drawdown measured at the pumping well karst conduit it shows that the matrix hydrodynamic parameters hydraulic conductivity and storativity have a greater influence on the drawdown than the storage capacity of the conduit the accuracy of the model relies mostly on a very good knowledge of both pumping rate and natural discharge at the spring with and without pumping this type of approach represents an advance in double continuum modeling of karst systems it also provides a methodology for the management of water resources from karst aquifers

groundwater age distributions at a public drinking water supply well field derived from multiple age tracers 85kr 3h 3he and 39ar 1 groundwater age is a key aspect of production well vulnerability public drinking water supply wells typically have long screens and are expected to produce a mixture of groundwater ages the groundwater age distributions of seven production wells of the holten well field netherlands were estimated from tritium helium 3h 3he krypton 85 85kr and argon 39 39ar using a new application of a discrete age distribution model and existing mathematical models by minimizing the uncertainty weighted squared differences of modeled and measured tracer concentrations the observed tracer concentrations fitted well to a 4 bin discrete age distribution model or a dispersion model with a fraction of old groundwater our results show that more than 75 of the water pumped by four shallow production wells has a groundwater age of less than 20 years and these wells are very vulnerable to recent surface contamination more than 50 of the water pumped by three deep production wells is older than 60 years 3h 3he samples from short screened monitoring wells surrounding the well field constrained the age stratification in the aquifer the discrepancy between the age stratification with depth and the groundwater age distribution of the production wells showed that the well field preferentially pumps from the shallow part of the aquifer the discrete groundwater age distribution model appears to be a suitable approach in settings where the shape of the age distribution cannot be assumed to follow a simple mathematical model such as a production well field where wells compete for capture area

effects of vegetation on braided stream pattern and dynamics 1 investigations using a 16 m by 2 m recirculating experimental flume model of an ephemeral braided river indicate that the presence of large and erosion resistant plants within the channel e g trees or shrubs can have a significant impact on channel pattern and planform dynamics simulations show that these plants have two effects first they act as obstructions in some cases forcing the flow to divide this flow separation can allow the deposition of a small island immediately in the lee of the plant splitting the channel the net result is a substantial increase in the number of channels and correspondingly the braid index this is in direct contrast to previous studies where increased levels of vegetation in perennial streams have decreased the braid index second the plants stabilize braid bars and can form relatively stable islands in their lee significantly reducing the longitudinal migration of islands typically associated with braided rivers

dynamic single thread channels maintained by the interaction of flow and vegetation most rivers on earth today flow as a single channel in some cases with occasional islands and follow a more or less sinuous course however single thread channels have proven difficult to reproduce and study experimentally experimental self formed channels tend to widen and subdivide leading to a braided pattern cohesive sediment has been the main mechanism studied for stabilizing banks and producing a single thread channel we show how laboratory experiments using vegetation to stabilize banks can organize the flow and convert the planform morphology from braided to single thread our experimental strategy a repeated cycle of short periods of high water discharge alternating with longer periods of low discharge accompanied by plant seeding and growth leads to the evolution of a dynamic self maintaining single thread channel with well defined banks and floodplain by eliminating weak flow paths the vegetation corrals the water into a single dominant channel until the reduction in total wetted width leads to a new self organized state in which the flow removes vegetated area as fast as it is produced the new channel is deeper and has a broader distribution of depths than the braided one with channel size adjusted to carry almost all the flood flow the resulting system maintains a dynamic steady state via similar mechanisms to those that operate in meandering channels in the field specifically erosion at the outside of bends bend growth and bar development our methodology provides a basis for experimental development of self sustaining high amplitude meanders and has applications for river management and basic research purposes

determination of a well head protection zone by stochastic inverse modelling abstract capture zones of wells play an important role in the protection of groundwater against pollution by persistent chemical compounds groundwater flow models can be used to delineate capture zones as however the accuracy and uniqueness of such models may be poor the outcome of a deterministic modelling exercise is likely to be unreliable in such a case stochastic modelling presents an alternative for the delineation of capture zones in this paper two methods are compared the unconditional and conditional monte carlo simulation in each method realizations of the aquifer characterized by a combination of recharge rates and transmissivity values are produced for each realization the capture zone of the well is determined by particle tracking by superposition of all capture zones produced a probability distribution is obtained that describes the probability of a point on the ground surface to belong to the capture zone this probability is given by the fraction of catchments among all realizations which contain the point conditioning the calculation with measured heads usually implies a zoning or spatial resolution of the transmissivity distribution the need for identification of large scale features for a meaningful zonation is stressed for a given zoned aquifer the influence of successively adding measured heads used to condition the stochasticsis studied with an increasing number of conditioning heads the probability distribution of the capture zone is shown to narrow this method allows the quantification of the value of measured head data

numerical simulation of unsaturated flow along preferential pathways implications for the use of mass balance calculations for isotope storm hydrograph separation an objective common to many watershed studies is to separate storm hydrographs into two components water that was present in the watershed prior to a storm event soil moisture and groundwater and water which fell on the watershed during the storm to use this approach a number of assumptions must be made including that the composition of water in the soil moisture and groundwater reservoirs are constant and known the objective of this paper is to show that in settings where flow and transport are dominated by preferential pathways for flow steady state mass balance calculations for quantitative hydrograph separation may be in error we present field data from a site where flow and transport are dominated by preferential pathways relict fractures in saprolite of sedimentary rocks which indicate that the 18o content of the water in the unsaturated and shallow saturated zones is not constant over the course of a storm event we use a numerical model to further explore the interactions between the fractures and surrounding matrix both the field data and modeling results indicate that the 18o of the previous storm event s has a strong influence on water in the fractures on the time scale of a storm event only the water in the matrix immediately surrounding the fracture mixes with water in the fracture while the bulk of the matrix is isolated from fracture flow the spatial and temporal heterogeneity of the 18o in the subsurface and the isolation of the most of the matrix water from flow in fractures make the measurement of a singular 18o value for subsurface reservoirs problematic and the assumption of a constant value doubtful since most near surface geologic materials have preferential flow paths we suggest that quantitative hydrograph separation using mass balance techniques is not possible in most situations future field and modeling investigations using the approach outlined here could be designed to explore the important temporal and spatial scales of variability in watersheds and lead to a more quantitative approach to storm hydrograph separation

relationships in regional groundwater discharge to streams an analysis by numerical simulation baseflow components of streamflow were determined for 32 selected basins in the plains regions of alberta plots of baseflow per unit area vs total basin surface q a curves show a rapid increase in baseflow rate with initial increase in basin area followed by a reduced rate of increase at larger basin areas thereby suggesting a functional dependence of baseflow rate on basin size the empirically determined baseflow relationships were studied by numerical simulations of groundwater flow in two dimensional vertical sections of type environments of the alberta plains these models show that the baseflow relationships develop according to the theory of regional gravity flow of groundwater the types of discharge relationships indicate greater baseflow in regional discharge areas areas of low topography and including local recharge regions than in regional recharge areas areas of high topography and including local discharge regions an asymptotic discharge drainage area relationship was obtained in this analysis which showed a high rate of increase of specific discharge with initial increase in basin area from the headwaters downgradient in the regional setting at and above a basin area of 10 000 km2 the rate of increase of specific discharge approaches a maximum value asymptotically with further increase in basin area the asymptotic relationship signifies the loss of water from high to low elevation in a flow pattern that consists of all local intermediate and regional systems several hydrogeological environmental parameters act to modify the shape and nature of the asymptotic relationship namely depth to width ratio regional slope and geology of the basin low depth to width ratio and low regional slope convert the asymptotic relationship to a stationary discharge drainage area relationship which gives a constant specific discharge for the entire range of basin area and identifies a flow pattern of wholly local systems contrarily high depth to width ratio high regional slope and the presence of aquifers in a basin transform the asymptotic relationship into a linear discharge drainage area relationship which describes a linear increase in specific discharge with basin area inverse discharge drainage area relationships or mirror images of all three above relationships are formed when specific discharge is plotted against basin area which increases from low elevation upgradient towards the headwaters the discharge drainage area relationships uncovered in this study demonstrate quantitatively that sub basins at low topographic elevations possess more water than those of equivalent sizes at high topography for example a basin with an area of 5000 m2 at a low topographic elevation discharges naturally at 1 4 10 2m3s 1m 2 whereas a similar basin at a high elevation would discharge at 7 8 10 3m3s 1m 2

new datings of amudian layers at qesem cave israel results of tl applied to burnt flints and esr u series to teeth abstract because only a few radiometric data are actually available the chronology of the amudian a blade dominated industry of the acheulo yabrudian cultural complex aycc of the late lower paleolithic in the levant is still not well constrained qesem cave offers the opportunity to enhance our knowledge of the chronological position of this industry which is unique to the levant the qesem amudian bearing layers yielded also human remains showing affinities with those of modern populations recovered in the middle paleolithic sites of skhul and qafzeh the results presented here are the first attempt to apply the tl and esr u series dating methods at this site and these methods yielded results which are generally in agreement they support a time interval of hominid bearing occupation of the areas of the cave where amudian lithic artifacts were recovered during mis 8 and likely 9 for the deep pit area and during mis 8 and possibly 7 for the upper part of the sequence square k 10 and the eastern microfauna bearing area an older occupation of the cave is also conceivable on the base of two dating results mis 11

impact of floods on the statistical distribution of riverbed vegetation investigating the colonization of river bars by pioneer vegetation we discuss how the balance between uprooting by flooding events and reinforcement of plant roots determines the ability for vegetation to colonize the riverbed in order to access the competition between growth and uprooting we work in a regime where the arrival time of flooding events is comparable with the timescales associated with vegetation i e plant germination and development rates we present new results for a flume experiment using converging channel walls and draw contrasts with previously published results for a simple channel with parallel sides this comparison highlights the role of varying local stream power in these processes we collected the statistics of vegetation root length number of roots and stem height for both riverbed and uprooted vegetation and show using a stochastic approach how the statistics for vegetation surviving in the riverbed alter a flood result from both the distribution of riverbed biomass before the flood and the distribution of biomass that is uprooted by the flood finally we compare our laboratory results with data obtained in a field experiment to show the similarities in the uprooting processes at both scales c 2012 elsevier b v all rights reserved

constraining permeabilities in a large scale groundwater system through model calibration abstract the range of field estimates of permeabilities in rocks of the atikokan research area ara canada has been reduced by calibrating a groundwater flow model of the ara the flow model was calibrated to the recharge component of the water balance and to measured freshwater heads in boreholes a good match between field and simulated recharge and between measured and simulated heads was obtained with two different permeability depth distributions that differed by up to two orders of magnitude in places solute transport simulation of the distributions of total dissolved solids tds chlorides cl and oxygen 18 18 o in groundwater in the area was performed to further refine the permeability estimates vertical average linear groundwater velocities from the calibrated flow model were used in one dimensional solute transport models of the system to generate depth concentration profiles of tds cl and 18 o recharge midline and discharge area models of both the fracture zones and the rock mass were employed the midline area is the narrow zone that separates the recharge downward flow area from the discharge upward flow area groundwater flow is essentially horizontal in the midline area envelopes formed by the simulated profiles that were created with the velocities of one simulation case more tightly enclosed the field data tds cl 18 o than those of another simulation case indicating that velocities of the former simulation case better represent the hydrodynamics of the real system the models demonstrate that the scatter of tds cl and 18 o field data for the ara is consistent with the groundwater flow model predictions and can be explained by the complexity arising from different hydraulic regimes recharge midline discharge and hydrogeologic environments fracture zones rock mass of the regional flow system solute transport simulation of hydrochemical constituents can aid in refining and constraining permeabilities in large scale groundwater systems

ecomorphodynamics of rivers with converging boundaries many rivers worldwide show converging sections where a characteristic limiting front for vegetation establishment on gravel bars is observed an important conceptual model was advanced in 2006 by gurnell and petts who demonstrated that for the convergent section of the tagliamento river the downstream front of vegetation establishment can be explained by unit stream power we introduce a theoretical framework based on 1d ecomorphodynamic equations modified to account for the biological dynamics of vegetation we obtain the first analytical result explaining the position and river width where vegetation density is expected to vanish in relation to a characteristic streamflow magnitude and both hydraulic and biological parameters we apply our model to a controlled experiment within a convergent flume channel with growing seedlings perturbed by periodic floods for a range of timescales where hydrological and biological processes interact we observe the formation of a front in the convergent section beyond which vegetation cannot survive the location of which is explained by flow magnitude this experiment confirms that the timescales of the involved processes and the unit stream power determine the existence and the position of the front within convergent river reaches respectively copyright c 2014 john wiley sons ltd

numerical simulation of groundwater flow for a coastal plain in japan data collection and model calibration using a three dimensional finite element model this study characterizes groundwater flow in a costal plain of the seto inland sea japan the model characterization involved taking field data describing the aquifer system and translating this information into input variables that the model code uses to solve governing equations of flow geological geometry and the number of aquifers have been analyzed based on a large amount of geological hydrogeological and topographical data results of study demonstrate a high correlation between the ground surface elevation and the groundwater level in the shallow coastal aquifer for calibrating the numerical groundwater model the groundwater flow was simulated in steady state in addition the groundwater level and trend in the transient state has also been elucidated the numerical result provides excellent visual representations of groundwater flow presenting resource managers and decision makers with a clear understanding of the nature of the types of groundwater flow pathways results build a base for further analysis under different future scenarios

experimental characterization of vegetation uprooting by flow we investigate vegetation uprooting by flow for avena sativa seedlings with stem to sediment size ratio close to unity and vanishing obstacle induced scouring by inducing parallel riverbed erosion within an experimental flume we measure the time to uprooting in relation to root anchoring and flow drag forces we link the erosion rate to the uprooting timescales for seedlings with varying mean root length we show that the process of continuous erosion leading to uprooting resembles that of mechanical fatigue where system collapsing occurs after a given exposure time by this analogy we also highlight the nonlinear role of the residual root anchoring versus the flow drag acting on the canopy when uprooting occurs as a generalization we propose a framework to extend our results to time dependent erosion rates which typically occur for real river hydrographs finally we discuss how the characteristic timescale of plant uprooting by flow erosion suggests that vegetation survival is conditioned by multiple erosion events and their interarrival time

hydrogeology of palm valley central australia a pleistocene flora refuge abstract the palm valley oasis finke gorge national park in arid central australia is characterised by large stands of red cabbage palm trees livistona mariae how these unique plants over 1000 km away from nearest relatives in the tropical parts of northern australia persist has long fascinated visitors the hydrogeology of this area helps explain this phenomenon stable isotope 2h 8o analyses shows groundwater to have a uniform composition that plots on or near a local meteoric water line carbon 14 results are observed to vary throughout this aquifer from effectively dead 100 ka along some flow paths indicate groundwater discharge would endure through arid phases associated with quaternary climate oscillations such a flow system can explain the persistence of this population of palms and also highlight the possibility that palm valley has acted as a flora refuge since at least the mid pleistocene

use of hydraulic tests at different scales to characterize fracture network properties in the weathered fractured layer of a hard rock aquifer the hydrodynamic properties of the weathered fractured layer of a hard rock pilot watershed in a granitic terrain are characterized using hydraulic tests at different scales the interpretation of numerous slug tests leads to characterize the statistical distribution of local permeabilities in the wells the application of flowmeter profiles during injection tests determines the vertical distribution of conductive fracture zones and their permeabilities it appears that the extension of the most conductive part of the weathered fractured layer is limited down to 35 meters depth the partition of drainage porosity between blocks 90 and fractures 10 is determined thanks to the interpretation of pumping tests using a double porosity model the application of anisotropic and single fracture analytical solutions on pumping test data allows to determine respectively the degree of anisotropy of permeability and the radius 4 to 16 meters of the horizontal conductive fractures crossed by the wells two different scales of fractures networks are identified the primary fracture network pfn which affects the matrix on a decimeter scale by contributing to an increase in the permeability and storage capacity of the blocks and the secondary fracture network sfn which affects the blocks at the borehole scale sfn is composed of two sets of fractures the main set of horizontal fractures is responsible for the sub horizontal permeability of the weathered fractured layer a second set of less permeable sub vertical fractures insures the connectivity of the aquifer at the borehole scale the good connectivity of fractures networks is shown by fractional dimension flow solutions the absence of scale effect in the study area suggests that the hydraulic conductivity at the borehole scale is laterally homogeneous finally the analysis and synthesis of the hydrodynamic properties allow to propose a comprehensive hydrodynamic model of the fractured weathered layer many geological and hydrogeological indicators suggest that a continuous and laterally homogeneous weathering process is responsible for the origin of the fractures and permeability encountered in the aquifer these results confirm the major role played by weathering in the origin of fractures and on resulting hydrodynamic parameters in the shallow part of hard rock aquifers

post mining deterioration of bauxite overburdens in jamaica storage methods or subsoil dilution rapid degradation of disturbed soil from a karst bauxite mine in jamaica was recorded substantial macronutrient losses were incurred during a short 1 month or a long 12 months storage of the replaced topsoils during frequent wet dry changes the results suggested very high rates 70 in the first year of soil degradation from storage alongside moderate rates 30 within the same storage dump however higher levels of soil organic matter som were indicated just below the surface compared with the surface horizons it was unlikely that under a high leaching humid tropical rainfall regime natural degradation processes could have re emplaced such material firmly intact in the 15 30 cm zone it was therefore concluded that these som anomalies were due to mechanical dilution of surface soil with subsoil material during overburden removal and emplacement rather than from long storage increasing the soil organic content during storage could be one corrective approach however it is far less costly to exercise greater care to apply more precise overburden removal and emplacement techniques initially than it is to correct the results of topsoil contamination with subsoil although this study was limited to one mine in the context of imminent large scale mining expansion and current practices further investigations are needed to accurately ascertain the proportion of similar subsoil contamination in other bauxite mined sites

a new method of characterizing fissured media by pumping tests with observation wells abstract an analogy has been defined between the relation s r t at n and the elementary solution derived from the general flow equation describing fluid flow in fissured media assuming a non integer flow dimension that analogy can be used to characterize a fissured medium by parameters that are similar to those describing a porous reservoir if at least two observation wells are available and if flow involves a sufficient number of fractures the flow system behaves as a fractal object with observation wells located along axes in several directions anisotropy can be characterized two field applications illustrate the proposed method

simulation of groundwater flow within observation boreholes for confined aquifers summary observation wells around a pumping well are the primary means of monitoring the change of hydraulic head in an aquifer pipe flow in open observation boreholes will affect the measurement of hydraulic head in the observation wells and alter the flow patterns around the wells but the influences of non darcian pipe flow in observation wells on the accuracy of hydraulic head measurements are not fully recognized this paper presents a coupled seepage pipe flow theory which integrates the aquifer and well as a continuous medium for assessing the influences the objective of this study is to examine the pipe flow effects in observation wells of varied diameters under several pumping scenarios including different penetration lengths of the pumping well a numerical model based on the galerkin finite element method and the finite difference method was developed for the study numerical simulations were conducted for a homogeneous and isotropic confined aquifer in which a pumping well penetrated a different thickness of the aquifer and a number of full penetrating observation wells were placed to obtain drawdowns the simulation results indicated that vertical pipe flow within the observation wells was significant and the flow was non linear the pipe flow resulted in a conduit effect that disturbed the distribution of the hydraulic head within the observation wells after comparing with the results of the hantush 1961 integral by using the case study which neglected the wellbore effect on the groundwater flow system the authors found that the hantush integral may be only conditionally applicable for estimating the drawdown within the observation wells when well diameter is greater than 0 20 m and radial distance is greater than the thickness of the aquifer our study suggests that use of hydraulic heads from observation wells for the evaluation of groundwater flow systems must be cautious before the pipe flow effect can be assumed to be negligible