a long term study of stable isotopes as tracers of processes governing water flow and quality in a lowland river basin the upper thames uk a long term study of o h and c stable isotopes has been undertaken on river waters across the 7000 km2 upper thames lowland river basin in the southern uk during the period flow conditions ranged from drought to flood a 10 year monthly record 2003 2012 of the main river thames showed a maximum variation of 3 18o and 20 2h though inter annual average values varied little around a mean of 6 5 18o and 44 2h the 2h 18o slope of 5 3 suggested a degree of evaporative enrichment consistent with derivation from local rainfall with a weighted mean of 7 2 18o and 48 2h for the period a tendency towards isotopic depletion of the river with increasing flowrate was noted but at very high flows 100 m3 s a reversion to the mean was interpreted as the displacement of bank storage by rising groundwater levels corroborated by measurements of specific electrical conductivity a shorter quarterly study october 2011 april 2013 of isotope variations in 15 tributaries with varying geology revealed different responses to evaporation with a high inverse correlation between 18o and baseflow index bfi for most of the rivers a comparison with aquifer waters in the basin showed that even at low flow rivers rarely consist solely of isotopically unmodified groundwater long term monitoring 2003 2007 of carbon stable isotopes in dissolved inorganic carbon dic in the thames revealed a complex interplay between respiration photosynthesis and evasion but with a mean inter annual 13c dic value of 14 8 0 5 exchange with atmospheric carbon could be ruled out quarterly monitoring of the tributaries october 2011 april 2013 indicated that in addition to the above factors river flow variations and catchment characteristics were likely to affect 13c dic comparison with basin groundwaters of different alkalinity and 13c dic values showed that the origin of river baseflow is usually obscured the findings show how long term monitoring of environmental tracers can help to improve the understanding of how lowland river catchments function

hydrologic connections of a stream aquifer vegetation zone in south central platte river valley nebraska field investigation and numerical modeling approaches were used to examine the hydrologic relations between the platte river and the adjacent alluvial aquifer and riparian zone in south central nebraska field methods include direct push techniques for coring and electric logging in the river channel permeameter tests for estimating the hydraulic conductivity of the streambed and monitoring of groundwater levels responding to changes in stream stages and to groundwater evapotranspiration the channel sediments consist mostly of coarse sand and gravels at the study site with large values of horizontal and vertical hydraulic conductivity groundwater in the riparian zone responded nearly simultaneously to the changes in stream stages and diurnal fluctuations of the water table are correlated with fluctuations of stream stage in summer all these indicate a well connected river aquifer vegetation hydrologic system numerical models based on the galerkin finite element method were developed to construct detailed flow nets for examining the changes in the patterns of groundwater flow dynamics resulting from the use of groundwater and stream water by riparian vegetation simulation results suggest that a number of hydrologic factors such as the thickness of the aquifer and vertical anisotropy of aquifer hydraulic conductivity also affect the flow patterns vertical flow is a major component more significant than the horizontal flow below the river and the vegetation zone in the growing season groundwater evapotranspiration can bring deeper groundwater to the water table by hydraulic lift this function of riparian vegetation could cause a complicated situation in an investigation of groundwater quality in riparian zones

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

how partial melts of mafic lower crust affect ascending magmas at oceanic ridges we present experiments showing that the lower oceanic crust should melt efficiently and quickly when heated by hot ascending magmas average plagioclase olivine and plagioclase augite pairs from the lower crust at the southwest indian ridge have melt mineral saturation boundaries at 1 190 and 1 154 c respectively and melt rapidly 0 01 mm h at 50 c or more above these temperatures melting experiments performed on olivine plagioclase and augite plagioclase mineral pairs from actual oceanic lower crustal rock samples and under conditions applicable to a mor setting 1 220 1 330 c 1 atm quartz fayalite magnetite oxygen buffer 0 25 24 h indicate that the resulting disequilibrium melts are linear mixes of the mineral compositions the rates of melting are slower than the rate of heat diffusion into a sample and are approximated as 2 43 10 26 e0 004109 t degc m s1 2 for augite melted with plagioclase 3 47 10 15 e0 002041 t degc for plagioclase melted with augite and 1 79 10 21 e0 0032 t degc for plagioclase melted with olivine our results indicate that great care must be taken in backward models using basalt chemistry alone to explore mantle melting processes assuming only crystallization and fractionation during ascent as partial melts may mix with intruded hot magma

simulation of groundwater exchange between an unconfined aquifer and a discrete fracture network with laminar and turbulent flows abstract in this study a new approach is developed to simulate groundwater flow through both an overlying unconfined aquifer and an underlying discrete fracture network the groundwater exchange between the aquifer and the fracture network including magnitude and direction is explicitly simulated based on the mass conservation which depends on a variety of parameters related to flow and network characteristics in the overlying unconfined aquifer we approximate the flow using the dupuit assumptions in the underlying fracture network we use the cubic law and forchheimer s law to iteratively simulate laminar or turbulent flow in individual fractures depending on the reynolds number explicitly separating laminar and turbulent flows in the fractures results in a system of nonlinear equations which is iteratively solved while the flow from the overlying unconfined aquifer is a small portion of the overall flow in the underlying fracture network incorrect use of the laminar or turbulent flow equation in the fractures can lead to significant errors in simulating the flow exchange as apertures increase both the portion of the total flowrate in the aquifer and the portion of the flow in the fractures coming from the aquifer decrease as the overall hydraulic gradient increases both the portion of the total flow in the aquifer and the portion of the fracture flow that comes from the aquifer increase the portion of the total flow in the aquifer increases with the aquifer thickness while the portion of fracture flow coming from the overlying aquifer decreases

river stage influences on uranium transport in a hydrologically dynamic groundwater surface water transition zone a well field within a uranium u plume in the groundwater surface water transition zone was monitored for a 3 year period for water table elevation and dissolved solutes the plume discharges to the columbia river which displays a dramatic spring stage surge resulting from snowmelt groundwater exhibits a low hydrologic gradient and chemical differences with river water river water intrudes the site in spring specific aims were to assess the impacts of river intrusion on dissolved uranium uaq specific conductance spc and other solutes and to discriminate between transport geochemical and source term heterogeneity effects as a result of water table elevation fluctuations river water intrusion and changes in groundwater flow directions time series trends for uaq and spc were found to be complex and displayed large temporal and well to well variability the wells were clustered into subsets exhibiting common behaviors resulting from the intrusion dynamics of river water and the location of source terms hot spots in uaq varied in location with increasing water table elevation through the combined effects of advection and source term location heuristic reactive transport modeling with pflotran demonstrated that mobilized uaq was transported between wells and source terms in complex trajectories and was diluted as river watermore entered and exited the groundwater system moreover while uaq time series concentration trends varied significantly from year to year as a result of climate caused differences in the spring hydrograph common and partly predictable response patterns were observed that were driven by water table elevation and the extent and duration of river water intrusion less

low melt fraction connectivity of granitic and tonalitic melts in a mafic crustal rock at 800 c and 1 gpa in the absence of an externally applied stress the segregation of small amounts of granitic or tonalitic melts from their residual mafic crystals is possible only if the melt forms an interconnected network phase accordingly this research focuses on melt connectivity at low melt fraction 4 wt or 5 vol connectivity of granitic and tonalitic melts in amphibole rich rock was assessed by performing two types of piston cylinder experiments at 1 gpa and 800 c the first involved annealing samples that consisted of either alternating layers or homogeneous mixtures of calcic amphibole and metaluminous obsidian powder the second type of experiment involved creating diffusion couples here an upper cylinder of amphibole saturated granitic or tonalitic melt was placed against a lower cylinder consisting of an amphibole rich rock containing zero or a small melt granitic or tonalitic fraction the upper part of the diffusion couple was doped with emitter 151sm or 14c and functioned as an infinite melt reservoir the lower part of the diffusion couple was considered to be the host rock the experiments approached textural equilibrium which allowed us to characterize the wetting behaviour of the calcic amphibole by the hydrous silicic melt granitic or tonalitic these particular experiments also provided information concerning diffusive transport because the emitter could diffuse through the connected melt liquid in the amphibole rich rock the dihedral angle measurements show that melt connectivity was achieved this conclusion is based on the fact that the dihedral angles consistently yielded median apparent values of 53 58 for an amphibole rich rock granitic melt system and 46 48 for an amphibole rich rock tonalitic melt system however the frequency distribution of angles is found to be relatively broad the results of the diffusion couple experiments assessed using the radiographic technique complement the dihedral wetting angle measurements by showing that melt connectivity is achieved at a melt fraction less than 4wt 5 vol

time series analyses for karst river interactions assessment case of the coulazou river southern france summary in many karst systems throughout the world numerous karst features facilitate the exchange of water between the surface the vadose zone and the saturated zone of the aquifer these interactions play actually a prominent role in the ground and surface waters circulation this study aims at assessing karst river interactions by the way of flood hydrograph analysis and new tools for time series analysis in this field of research as in many others binary karst system the captured waters of the coulazou river travel through conduits and preferential flow paths in the vadose zone and join the saturated zone of the aquifer this river is an ephemeral river in a mediterranean context where rapid and intense floods occur each year this hydrologic behaviour is appropriate to study the transfer of a flood through a karst area the water level in caves the rainfall all over the karst aquifer catchment area the piezometric level within the karst aquifer and the discharge in the river upstream and downstream of the karst aquifer are measured in order to understand the karst river exchanges during a flood the modification of the surface flows in the river is treated as a linear time invariant system lti system correlation and spectral analyses are used to understand how the lti system dissipates or enhances the flood wave energy for several floods the frequency response function estimations are interpreted in term of flood wave modification through the karst area in this way according to the initial state of the karst river system the autogenic and or allogenic recharge of the aquifer may induce surge flows and a significant karst contribution to surface flows

river stage tomography a new approach for characterizing groundwater basins received 19 june 2008 revised 16 february 2009 accepted 12 march 2009 published 9 may 2009 1 data from tomographic surveys make an inverse problem better posed in comparison to the data from a single excitation source a tomographic survey provides different coverages and perspectives of subsurface heterogeneity nonfully redundant information of the subsurface fusion of these pieces of information expands and enhances the capability of a conventional survey provides cross validation of inverse solutions and constrains inherently ill posed field scale inverse problems basin scale tomography requires energy sources of great strengths spatially and temporally varying natural stimuli are ideal energy sources for this purpose in this study we explore the possibility of using river stage variations for basin scale subsurface tomographic surveys specifically we use numerical models to simulate groundwater level changes in response to temporal and spatial variations of the river stage in a hypothetical groundwater basin we then exploit the relation between temporal and spatial variations of well hydrographs and river stage to image subsurface heterogeneity of the basin results of the numerical exercises are encouraging and provide insights into the proposed river stage tomography using naturally recurrent stimuli such as river stage variations for characterizing groundwater basins could be the future of geohydrology however it calls for implementation of sensor networks that provide long term and spatially distributed monitoring of excitation as well as response signals on the land surface and in the subsurface

green mosses date the storegga tsunami to the chilliest decades of the 8 2 ka cold event abstract chlorophyll in dead plants ordinarily decomposes completely before permanent burial through exposure to light water and oxygen here we describe 8000 year old terrestrial mosses that retain several percent of its original chlorophyll the mosses were ripped of the land surface carried 50 100 m off the norwegian coast of the time and deposited in depressions on the sea floor by the storegga tsunami a little of the chlorophyll survived because within hours after entraining it the tsunami buried the mosses in shell rich sediments these sediments preserved the chlorophyll by keeping out light and oxygen and by keeping the ph above 7 three factors known to favour chlorophyll s stability because the green mosses were buried alive their radiocarbon clock started ticking within hours after the storegga slide had set off the tsunami radiocarbon measurement of the mosses therefore give slide ages of uncommon geological precision and these together with a sequence of ages above and below the boundary date the storegga slide to the chilliest decades of the 8 2 ka cold event at 8120 8175 years before ad 1950 north atlantic coastal and fjord climatic records claimed to show evidence of the 8 2 cold event should be carefully examined for possible contamination and disturbance from the storegga tsunami

recharge of aquifers by flood events in an arid region the process of aquifer recharge by flood events in an arid region was investigated as applied to the hazeva formation the karkom graben the wadi paran watershed israel the hydrological model was established as a complex system with due regard for groundwater and transmission losses of surface runoff it was based on a previously outlined hydrogeological model of the karkom graben and a model of transmission losses in arid watercourses under conditions of data deficiency proceeding from calculation of groundwater balances the contribution of surface runoff as a decisive balance component was confirmed the main characteristics of aquifer regimes such as changes in storage volume and groundwater level as well as lateral flow were all found to be dependent upon the net extraction rate i e pumpage discounting replenishment by flood events analysis and physical interpretation of model parameters enabled assessment of the influence of groundwater extraction on aquifer recharge this became apparent as increasing absorption capacity and recharge availability of the aquifer as a result of the groundwater abstraction copyright 2002 john wiley sons ltd

the storegga slide tsunami comparing field observations with numerical simulations abstract deposits from the storegga tsunami have been found in coastal areas around the norwegian sea and north sea from the northeast coast of england to beyond the arctic circle in northern norway the tsunami deposits reach onshore elevations of 10 12 m above sea level of their time in western norway 3 6 m in northeast scotland and above 20 m on the shetland islands these elevations are compared with surface wave elevations derived from a numerical simulation of the storegga slide a good agreement is obtained for a retrogressive slide that descends at 25 30 m s and that has short time lags of 15 20 s between each individual slide block

dissolution of corundum and andalusite in h2o saturated haplogranitic melts at 800 c and 200 mpa constraints on diffusivities and the generation of peraluminous melts of h2o in the aluminum alkali eigenvector could not be obtained the mechanisms and kinetics of equilibration between peraluminous from our results we propose that some h2o may provide charge minerals and granitic melt were investigated experimentally by balance for excess aluminum multicomponent diffusion models the dissolution of corundum and andalusite into h2o saturated yield eigenvalues for the corresponding aluminum alkali eigenvector metaluminous haplogranitic melt at 800 c and 200 mpa mineral of 0 3 10 to 1 9 10 cm s calculated effective and haplogranitic glass rods were juxtaposed inside platinum binary diffusion coefficients for al2o3 are higher 1 0 10 to capsules and then subjected to experimental conditions for times 3 6 10 cm s these diffusion coefficients are used to ranging from 12 to 2900 h upon melting the mineral melt calculate equilibration times between peraluminous minerals and interface retreats with the square root of time the composition of granitic melts in a model system in which two grains of corundum the melt at the interface changes with time but its asi aluminum or andalusite 1 cm apart are connected via a narrow melt column saturation index molar al2o3 cao na2o k2o at the conditions of the experiments diffusive equilibrium through remains constant at 1 20 after 480 h this value is close to initially metaluminous h2o saturated melt would be attained within the asi of an h2o saturated haplogranitic melt in equilibrium with 10 10 years at h2o activity well below saturation of the corundum or andalusite which may indicate that the composition of melt lower diffusivity of all components may increase the time to the melt at the interface follows the liquidus of these minerals in equilibration to 10 10 years approaching possible time frames the system sodium and potassium diffuse rapidly uphill across the for the generation and extraction of crustal melts entire length of the charge towards the interface resulting in a rapid and uniform increase in asi throughout the entire melt column this uphill diffusion of alkalis is due to coupling with excess aluminum entering the melt at the interface and involves long range

field experiments and numerical simulations of confined aquifer response to multi cycle recharge recovery process through a well summary shanghai is one of the cities suffering from land subsidence in china land subsidence has caused serious financial losses thus artificial recharge measures have been adopted to compensate the drawdown in shallow confined aquifers and thereby control land subsidence in this study a multi cycle recharge recovery field experiment was performed to investigate the response of a shallow confined aquifer to artificial recharge through a well in the experiment a series of recharge recovery cycles with different recharge volumes and durations with and without artificial pressure were performed the water levels monitored in the recharge and observation wells indicated the response of the aquifer to the multi cycle recharge recovery process meanwhile a finite difference method fdm numerical model was established and its parameters were obtained via a reversed numerical analysis on the experimental data the responses of the shallow confined aquifer to the multi cycle recharge recovery process were simulated in detail using the model the calculation results showed that the water level dropped significantly when the recharge ended moreover the efficiency of a multi cycle recharge was found to be higher than that of a concentrated one under the same recharge volume and time the relationship between recharge frequency and efficiency expressed as h 0 29498 f 0 40163 and r 2 0 97264 respectively was obtained through the fdm numerical simulation in the recharge intervals the optimal recharge efficiency was achieved when the water level rose to 40 of the peak

hydraulic and thermal response of groundwater surface water exchange to flooding in an experimental aquifer summary the effects of flooding on interactions between streams and shallow aquifers are poorly studied due to the unpredictable nature of flooding events this study examines groundwater surface water interactions in a constructed experimental meander over several simulated flood events using hydrologic and thermal monitoring detailed steady state hydraulic head measurements were taken of the stream surface and in 59 piezometer nests during baseflow bankfull flow and overbank flooding conditions allowing for three dimensional hydrologic characterization additionally a lithium tracer test was conducted and pressure transducers and thermistors were deployed to capture transient behavior results demonstrate extensive coupling between the stream and adjacent alluvial aquifer under all discharge conditions water table elevation responds rapidly to changes in stream stage and re equilibrates to order of magnitude increases in discharge within about 1 h though flooding elevates the water table steady state hydraulic gradients within the meander are independent of stream stage this results from the flow boundary condition imposed by the stream which deepens in response to flooding but has a slope that is essentially independent of discharge in addition to the stream boundary flow within the meander is also controlled by loss of stream water to the subsurface which directs hydraulic gradients towards the base of the meander finally the temperature distribution within the meander during normal and bankfull flow mimics the water table distribution and results from advected warm stream water being progressively cooled by vertical conduction in the direction of groundwater flow these findings suggest that areas of high reaction rates within meanders hot spots will be sensitive to whether a stream reach is gaining or losing water to the subsurface further the location of these hot spots of is likely independent of stream stage though other controls on reaction rates may be affected

a review and analysis of silicate mineral dissolution experiments in natural silicate melts abstract we present a database and a graphical analysis of published experimental results for dissolution rates of olivine quartz plagioclase clinopyroxene orthopyroxene spinel and garnet in basaltic and andesitic melts covering a range of experimental temperatures 1100 1500 c and pressures 10 5 pa 3 0 gpa the published datasets of donaldson 1985 1990 and brearly and scarfe 1986 are the most complete experimental dissolution rates from all datasets are recalculated and normalized to a constant oxygen basis to allow for direct comparison of dissolution rates between different minerals dissolution rates range from 5 10 10 oxygen equivalent moles o e m cm 2 s 1 for olivine in a basaltic melt to 1 3 10 5 o e m cm 2 s 1 for garnet in a basaltic melt values of ln are arthenian for the experiments examined and activation energies range from 118 to 1800 kj o e m for quartz and clinopyroxene respectively the relationship between calculated a rt for the dissolution reactions where a is the thermodynamic potential affinity and values of is linear for olivine plagioclase and quartz we interpret this as strong evidence in support of using calculated a as a predictor of for at least superliquidus melt conditions

transient head development due to flood induced seepage under levees the purpose of this study was to predict the uplift force during floods on confining layers that overlay extensive horizontal confined aquifers that intersect a large river in response to the water level changes that occur with time in a flooding river transient flow of water through the confined aquifer was described by a diffusion type of equation with a boundary condition at the river in which the river head varied with time the transient head distribution developed from the unsteady flow model applied to the aquifer was compared with the hydraulic head distributions obtained from u s army corps of engineers steady state flow model and a finite element seepage model this study concluded that the transient flow model has the potential to analyze time lag in head development and to predict the seepage condition and heaving potential at various times and distances landside of a levee during a flood cycle but additional case histories are needed to justify widespread use of the model

dynamics of floodplain island groundwater flow in the okavango delta botswana abstract surface water groundwater interactions play a crucial role in the hydrology and ecology of the okavango delta the hydrology of the delta is dominated by the annual arrival of a flood wave which is distributed over an number of branches subsequently the flood water feeds the phreatic aquifers underlying the delta islands in order to evaluate the seasonal and long term dynamics of the surface water groundwater interactions between the floodplains and the islands a network of piezometers located in various locations of the delta was monitored groundwater table fluctuations observed for up to 6 years were analysed and modelled using groundwater flow models the floodplain island groundwater flow is in general very dynamic and driven by island evaporation and transpiration a typical small to medium sized island width 500 m and at the perimeter of the flooded area is the influence of long term antecedent conditions apparent the knowledge gained during this study will be used for the improvement of the hydrological and hydro ecological model of the delta and can be useful for the description of floodplain dynamics in semi arid regions in general

magmatic subsidence of the east pacific rise epr at 18 14 s revealed through fault restoration of ridge crest bathymetry 1 the fault restoration technique of de chabalier and avouac 1994 is applied to an ultra high resolution bathymetry data set from the east pacific rise epr at 18 14 s fault offsets are calculated and subtracted from the original seafloor bathymetry to examine the morphology of the unfaulted seafloor surface within an area encompassing the ridge axis 400 1600 m in dimension the restored topography reveals a gently sloping seafloor 200 m wide which slopes 5 inward toward the spreading axis we attribute this inward sloping seafloor to subsidence within the axial trough due to subsurface magmatic deflation the vertical deformation field extracted from the bathymetry is used to characterize the ridge axis fault population present in the area median fault throws 9 m for inward facing and 8 m for outward facing faults are comparable to values measured for nearby mature abyssal hill fault populations suggesting a genetic link however median fault spacings 70 and 46 m are an order of magnitude smaller and estimated total extensional strain is 3 4 greater than values measured for ridge flank faults these differences indicate the axial fault population at 18 14 s cannot be rafted onto the ridge flanks to form abyssal hill faults without significant modification presumably via volcanic burial we attribute the dense faulting observed in this area to slip on axial fissures during subsidence of the crestal region the surface subsidence of a volcanic edifice can be modeled in terms of volume change in the magma source reservoir and volume of magma withdrawn from the reservoir using the relationship derived for a sill like magma body we estimate that the axial depression at 18 14 s could represent magma withdrawal associated with a small number 4 22 of the frequent dike injection and eruption events required to build the upper crust during the evolution of the trough the subsidence volumes represented by the axial topography at 18 14 s are a small percentage of the underlying upper crustal sections 3 4 suggesting that only a minor mismatch between magma recharge and withdrawal from the axial melt lens during ongoing plate separation could account for this pronounced axial depression

transient flow to a large diameter well in an aquifer with storative semiconfining layers the hantush theory of leaky aquifers with storge in the semiconfining layers is combined with large diameter well theory to produce equations that can be used in the analysis of pumped well and observation well data for stratified formations included in the equations are storage in the pumped well and a linear resistance to flow at the sand face or well bore skin three cases proposed by hantush are considered these depend upon whether the upper boundary of the overlying semiconfining layer or the lower boundary of the underlying semiconfining layer are constant head or no flow boundaries laplace transform solutions valid for the complete time domain are given for each of the three cases for the hydraulic head in the pumped well the aquifer and each of the semiconfining layers type cures obtained by numerical inversion are selected to illustrate the effects of well bore storage well bore skin and leakage although several dimensionless parameters are involved these parameters tend to influence the character of different portions of the type curves suggesting that unique matches are possible the type curves show that well bore storage in a large diameter well may completely obliterate effects of leakage derived from compressible storage in semiconfining layers for the purposes of aquifer testing it may be possible to reduce the magnitude of well bore storage in a large diameter well and thus reveal the presence of leaky semiconfining layers this may help to prevent erroneous interpretation of the well test data and incorrect evaluation of the aquifer parameters

exact analytical expressions for the piezometric profile and water exchange between stream and groundwater during and after a uniform rise of the stream level 1 we consider an archetypical problem relevant to a confined aquifer in contact with a stream the model problem consists of an idealized one dimensional region 0 x l where the left boundary at x 0 is held at a fixed piezometric head h0 and the right boundary s piezometric head at x l is increased from hl to h0 at a constant rate exact solutions for all times all points in the aquifer and for any possible constant rate of change of the right boundary piezometric head are presented for the piezometric head and the instantaneous flow rate an exact expression for the exchange volume at the groundwater stream interface for an arbitrary time is also provided this expression shows that there is a specific critical rising rate of the stream level above which the net exchange volume is into the aquifer and below which it is out of the aquifer the solution shows that regardless of the rise rate a certain water volume inversely proportional to the rise rate enters the aquifer

modification of canal flow due to stream aquifer interaction unsteady canal flow in an integrated canal flow groundwater flow system is analyzed by solving the coupled equations governing canal flow groundwater flow and the seepage between them analytical solu tions are obtained for the coupled system for small water level disturbances using fourier analysis methods and complex variables dimensionless parameter groups characterizing the aquifer the canal and the sediment layer are identified using the governing equations and the solution the influence in the aquifer and the semipermeable bottom sediment layer due to disturbances in canal flow is studied the analytical solutions are compared to numerical solutions obtained using the modflow model and the hydrologic simulation engine of the south florida regional simulation model results of the analysis are useful in determining the range of aquifer sediment and canal characteristics for which stream aquifer interaction is important the results can be used to determine the conditions for which the canal is hydraulically disconnected from the aquifer because of the sediment layer the analytical solution is useful to understand the propagation characteristics of small amplitude water level disturbances in the canal and the aquifer the characteristics studied include the amplitude decay constant and the speed the solution can be used to design benchmark problems that can be used to evaluate integrated canal flow groundwater flow models the results of the study can be used to estimate the space and time steps needed in the canal and the aquifer when simulating stream aquifer interaction as part of the overall effort to restore the everglades eco system in south florida and to meet its regional water man agement responsibilities the south florida water management district sfwmd sfwmd 1999 and other organizations have developed a number of mathematical models to simulate the water management system one important requirement of these models is the capability to simulate stream aquifer in teraction or stream wetland interaction a significant part of the south florida landscape is covered with a network of ca nals that extends for thousands of miles through wetlands ag ricultural areas and urban areas the behavior of water levels in the canals when areas adjacent to canals are subjected to water level changes is not completely understood the influ ences of the highly conductive surface aquifer and the less conductive bottom sediment layer of the canal on the overall hydrology are also not completely known these behaviors influence a significant part of south florida hydrology the current study provides a method to understand the basic pa rameters that govern the problem and to obtain an analytical solution stream aquifer and stream wetland interactions have previ ously been studied by a number of researchers the study by pinder and sauer 1971 was conducted by using a coupled numerical model for canal flow and 2d groundwater flow the objective was to study the influence of bank storage on the modification of flood waves the example used by pinder and sauer 1971 served as a benchmark test for integrated mod els such as modbranch swain and wexler 1996 and modnet walton et al 1999 these models consist of a modflow model mcdonald and harbaugh 1988 coupled with either the branch model schaffranek 1987 or the unet model hec 1996 the comparison between the so lution obtained by pinder and sauer 1971 and the solutions obtained using modbranch or modnet was not perfect 1

olivine dissolution in molten silicates an experimental study with application to chondrule formation mg rich olivine is a ubiquitous phase in type i porphyritic chondrules in various classes of chondritic meteorites the anhedral shape of olivine grains their size distribution as well as their poikilitic textures within low ca pyroxene suggest that olivines suffer dissolution during chondrule formation owing to a set of high temperature experiments 1450 1540 c we determined the kinetics of resorption of forsterite in molten silicates using for the first time x ray microtomography results indicate that forsterite dissolution in chondrule like melts is a very fast process with rates that range from 5 m min 1 to 22 m min 1 forsterite dissolution strongly depends on the melt composition with rates decreasing with increasing the magnesium and or the silica content of the melt an empirical model based on forsterite saturation and viscosity of the starting melt composition successfully reproduces the forsteritic olivine dissolution rates as a function of temperature and composition for both our experiments and those of the literature application of our results to chondrules could explain the textures of zoned type i chondrules during their formation by gas melt interaction we show that the olivine liquid ratio on one hand and the silica entrance from the gas phase siog into the chondrule melt on the other hand have counteracting effects on the mg rich olivine dissolution behavior silica entrance would favor dissolution by maintaining disequilibrium between olivine and melt hence this would explain the preferential dissolution of olivine as well as the preferential abundances of pyroxene at the margins of chondrules incipient dissolution would also occur in the silica poorer melt of chondrule core but should be followed by crystallization of new olivine overgrowth and or newly grown crystals while explaining textures and grain size distributions of olivines as well as the centripetal distribution of low ca pyroxene in porphyritic chondrules this scenario could also be consistent with the diverse chemical isotopic and thermal conditions recorded by olivines in a given chondrule

glacier fluctuations equilibrium line altitudes and palaeoclimate in lyngen northern norway during the lateglacial and holocene based on lacustrine and morpho stratigraphical evidence from lyngen in troms northern norway 13 marginal moraines have been mapped in front of lenangsbreene in strupskardet moraines m1 m13 are inferred to represent glacier halts or advance readvance taking place during the lateglacial and holocene the presence of collapse depressions suggests that some of them were ice cored m1 m3 a chronological framework taking into account a combination of former shorelines and related glacier meltwater channels lichenometry and ams radiocarbon dated lacustrine sediments spanning the last 20 000 cal yr bp has been established the distal glacier fed lake aspvatnet was isolated from the sea c 10 300 cal yr bp and the lacustrine sediments have been investigated by use of loss on ignition loi magnetic susceptibility water content wet and dry bulk density dbd and the magnetic parameters anhysteretic remanent magnetization arm and saturation remanent magnetization sirm there is in general good agr

buffer effect on identifying transient streambed hydraulic conductivity with inversion of flood wave responses abstract determination of streambed hydraulic conductivity ksb and its variations over time are critical for quantifying exchange fluxes between surface water and groundwater previous studies have used flood wave response techniques frt to determine ksb or its transience excluding the streambed storage effect thus the estimated ksb may not be reliable in this study after improving a previous frt by substituting the gradient descent algorithm with an advanced and robust optimization method trust region reflective algorithm we have analyzed the influence of streambed storage effect on the estimation of time dependent ksb through successive inversion of flood wave responses the study shows that the streambed storage effect is not important for identifying the transience in the hydraulic properties of a relatively thin streambed e g several or dozens of centimeters but significant under estimation 1 2 orders of magnitude can be seen because of neglecting the streambed storage effect it is particularly true for a stream confined aquifer system if the streambed is composed of fine deposits e g silt clay with a thicker thickness greater than 1 m corresponding to low permeability but high storativity and the aquifer is characterized by relatively low permeability e g roughly 0 1 10 m d 1 and relatively low storativity roughly 1e 5 m 1 e g dense fine sands the new method in which streambed storage effect is incorporated can provide more reliable estimations of time dependent ksb for a stream confined aquifer system and it has been successfully applied to estimate the time dependent ksb of a reach of the arkansas river kansas usa

effects of melt viscosity and silica activity on the rate and mechanism of quartz dissolution in melts of the cmas and cas systems the dissolution rate of quartz in melts of the cmas and cas systems at 1 600 c and 1 5 gpa is a function of both the silica activity of the melt and its viscosity in melts with low silica activity quartz dissolves more quickly than in higher asio2 melts regardless of viscosity for melts with equal asio2 dissolution is faster in the low viscosity melt quartz dissolution is controlled by interface kinetics in three of the four melts used in this study for times much greater than predicted by the model of zhang et al in contrib mineral petrol 102 492 513 1989 one melt which was previously shown to adhere to the predicted behaviour at lower temperature shows a significant activation time at higher temperature all the dissolution data indicate that there are likely to be three distinct domains of dissolution behaviour although the details of why a particular melt falls in any one domain require further study although the current database is small the relationship between quartz solubility and the dissolution constant indicate that solubility may be a useful parameter for predicting dissolution rates particularly if silica activity and melt viscosity are also known

numerical modeling the role of rubber dams on groundwater recharge and phreatic evaporation loss in riparian zones rubber dams have been widely built for their advantages in increase of flooding resources utilization in the north arid and semiarid plain regions of china rise in river water stage by the dams particularly during the drought periods increases lateral seepage of river water into groundwater and thus groundwater table and phreatic evaporation loss in the riparian zones in this study a riparian area of the baihe river in nanyang of henan province china was selected for investigation of influences of the river dams on the groundwater recharge and evaporation loss a hydraulic model hec ras was used for simulation of the river stage variations along the baihe river and a numerical groundwater model modflow was applied for simulation of groundwater dynamics and estimation of river flow seepage into aquifer and evaporation loss the results show that the dams increase river stages of 2 3 m during january 2000 december 2002 the increase in the captured groundwater recharge was 7 15 34 06 million m3 a and the increased phreatic evaporation loss occupies 10 of the increased recharge when four rubber dams were built

marine 14c reservoir ages for 19th century whales and molluscs from the north atlantic abstract in order to compare radiocarbon dates on marine and terrestrial samples the former have to be corrected for a reservoir age we present reservoir ages from dating 21 whales collected 1860 1901 and recalculating dates of 23 molluscs collected 1857 1926 most of the whales were caught along the coast of norway but one is from france and one from iceland we assume the former mainly lived in the north and equatorial atlantic and in the norwegian sea whales feed only on pelagic organisms and will provide the reservoir age for the open ocean surface water however they travel long distances and will integrate the reservoir ages of the different water masses along their way molluscs dated from norway spitsbergen and arctic canada are stationary and monitor the sea water passing their dwelling site but some also take up carbon from particulate food or sediment pore water coastal water also often contains some continental carbon we present two different views on how to analyze and interpret the data mangerud recommends to use reservoir ages based on a combination of the whale and mollusc dates i e 380 30 and 360 30 yr relative to intcal04 and british oak respectively and a r value of 20 30 for the surface water in the n atlantic and norwegian sea bondevik and gulliksen maintain that the reservoir age and r along the norwegian coast is latitude dependant with r values increasing from 3 22 in the south to 105 24 at spitsbergen whales reflecting north atlantic open ocean surface water have lower r 7 11 than most molluscs

postglacial uplift and relative sea level changes in finnmark northern norway abstract the outer coast of finnmark in northern norway is where the former fennoscandian and barents sea ice sheets coalesced this key area for isostatic modelling and deglaciation history of the ice sheets has abundant raised shorelines but only a few existing radiocarbon dates constrain their chronology here we present three holocene sea level curves based on radiocarbon dated deposits from isolation basins at the outermost coast of finnmark located at the islands soroya and rolvsoya and at the nordkinn peninsula we analysed animal and plant remains in the basin deposits to identify the transitions between marine and lacustrine sediments terrestrial plant fragments from these transitions were then radiocarbon dated radiocarbon dated mollusk shells and marine macroalgae from the lowermost deposits in several basins suggest that the first land at the outer coast became ice free around 14 600 cal yr bp we find that the gradients of the shorelines are much lower than elsewhere along the norwegian coast because of substantial uplift of the barents sea also the anomalously high elevation of the marine limit in the region can be attributed to uplift of the adjacent seafloor after the younger dryas the coast emerged 1 6 1 0 cm per year until about 9500 9000 cal yr bp between 9000 and 7000 cal yr bp relative sea level rose 2 4 m and several of the studied lakes became submerged at the outermost locality rolvsoya relative sea level was stable at the transgression highstand for more than 3000 years between ca 8000 and 5000 cal yr bp deposits in five of the studied lakes were disturbed by the storegga tsunami ca 8200 8100 cal yr bp

the temporal evolution of three magmatic systems in the west eifel volcanic field germany abstract the quaternary west eifel volcanic field is the surface expression of a mantle plume that is thought to contain 1 melt the volcanoes range in age from 0 7 ma to 10 000 yr bp and the average recurrence rate of volcanism is around 3 5 10 4 eruptions per year giving a mean time between eruptions of 2875 years assuming that the field is monogenetic the presence of mafic and ultramafic xenoliths is taken as evidence for rapid single stage emplacement of magmas at velocities around 0 5 km h however the presence of clinopyroxene that preserves evidence of polybaric crystallisation belies this simple model this study uses variations in the fo content of olivine in mantle derived xenoliths and in olivine xenocrysts enclosed in cumulate xenoliths to calculate the time scale of evolution of three volcanic centres in the eifel field core rim variations in olivine are interpreted to result from fe mg interdiffusion between it and a surrounding melt using experimental determinations of the interdiffusion coefficient and approximations of magma temperature contact times have been calculated using planar and radial diffusion models the three volcanic centres studied were meerfelder maar gemundener maar and baarley the cumulate xenoliths at meerfelder maar formed at a depth of 13 km and record a magma emplacement event at between 1 and 3 years prior to eruption two suites of mantle derived olivine clinopyroxenites record a further two events at 1 8 days and 3 h prior to eruption the final event is interpreted to record the eruption of this volcano and the 3 h contact time records the time required for transport of peridotite xenoliths from the mantle to surface giving an average emplacement velocity of around 15 km h the cumulate xenoliths at gemundener maar crystallised at depths of between 4 and 22 km there are four distinct events recorded by the zoned olivine grains in the clinopyroxene rich cumulates from this locality the maximum residence time is similar to that at meerfelder maar however in this case the final magma resided in the chamber for between 23 days and 2 7 months prior to eruption allowing enough time for any entrained peridotite xenoliths to be filtered out the cumulate xenoliths from the baarley locality record a much longer history than those at the other localities in this case initially peridotitic olivine has been completely re equilibrated over 175 years prior to eruption in common with the other two localities there is evidence of multiple intrusive events at depths up to 7 km prior to final eruption the duration of the final eruption event and the interpreted depth to source of the xenoliths indicate an emplacement velocity of around 3 km h the data derived from modelling of diffusion profiles in olivine from cumulate xenoliths indicate that the magmatic systems feeding these three volcanoes were dynamic and very short lived in addition these data can be used to place constraints on the rate of cumulate formation in subvolcanic magma chambers on the basis of the data presented here it would seem that an appreciable thickness of cumulates can form over relatively short time spans days to a few years

aquifer response to stream stage and recharge variations i analytical step response functions abstract laplace transform step response functions are presented for various homogeneous confined and leaky aquifer types and for anisotropic homogeneous unconfined aquifers interacting with perennial streams flow is one dimensional perpendicular to the stream in the confined and leaky aquifers and two dimensional in a plane perpendicular to the stream in the water table aquifers the stream is assumed to penetrate the full thickness of the aquifer the aquifers may be semi infinite or finite in width and may or may not be bounded at the stream by a semipervious streambank the solutions are presented in a unified manner so that mathematical relations among the various aquifer configurations are clearly demonstrated the laplace transform solutions are inverted numerically to obtain the real time step response functions for use in the convolution or superposition integral to maintain linearity in the case of unconfined aquifers fluctuations in the elevation of the water table are assumed to be small relative to the saturated thickness and vertical flow into or out of the zone above the water table is assumed to occur instantaneously effects of hysteresis in the moisture distribution above the water table are therefore neglected graphical comparisons of the new solutions are made with known closed form solutions

tsunami sedimentary facies deposited by the storegga tsunami in shallow marine basins and coastal lakes western norway sedimentary successions in small coastal lakes situated from 0 to 11 m above the 7000 year bp shoreline along the western coast of norway contain a distinctive deposit very different from the sediments above and below the deposit is interpreted to be the result of a tsunami inundating the coastal lakes an erosional unconformity underlies the tsunami facies and is traced throughout the basins with most erosion found at the seaward portion of the lakes the lowermost tsunami facies is a graded or massive sand that locally contains marine fossils the sand thins and decreases in grain size in a landward direction above follows coarse organic detritus with rip up clasts here termed organic conglomerate and finer organic detritus the tsunami unit generally fines and thins upwards the higher basins 6 11 m above the 7000 year shoreline show one sand bed whereas basins closer to the sea level 7000 years ago may show several sand beds separated by organic detritus these alternations in the lower basins may reflect repeated waves of sea water entering the lakes in basins that were some few metres below sea level at 7000 years bp the tsunami deposit is more minerogenic and commonly present as graded sand beds but also in some of these shallow marine basins organic rich facies occur between the sand beds the total thickness of the tsunami deposit is 20 100 cm in most studied sites an erosional and depositional model of the tsunami facies is developed

changes in north atlantic radiocarbon reservoir ages during the allerod and younger dryas estimates of the radiocarbon age of seawater are required in correlations between marine and terrestrial records of the late quaternary climate we radiocarbon dated marine shells and terrestrial plant remains deposited in two bays on norway s west coast between 11 000 and 14 000 years ago a time of large and abrupt climatic changes that included the younger dryas yd cold episode the radiocarbon age difference between the shells and the plants showed that sea surface reservoir ages increased from 400 to 600 years in the early yd stabilized for 900 years and dropped by 300 years within a century across the yd holocene transition

stream water infiltration bank storage and storage zone changes due to stream stage fluctuations abstract during a flood period stream stage increases induce infiltration of stream water into an aquifer subsequent declines in stream stage cause a reverse motion of the infiltrated water this paper presents the results of the water exchange rate between a stream and aquifer the storage volume of the infiltrated stream water in the surrounding aquifer bank storage and the storage zone the storage zone is the part of aquifer where groundwater is replaced by stream water during the flood modflow was used to simulate stream aquifer interactions and to quantify rates of stream infiltration and return flow modpath was used to trace the pathlines of the infiltrated stream water and to determine the size of the storage zone simulations were focused on the analyses of the effects of the stream stage fluctuation aquifer properties the hydraulic conductivity of streambed sediments regional hydraulic gradients and recharge and evapotranspiration et rates on stream aquifer interactions generally for a given stream aquifer system larger flow rates result from larger stream stage fluctuations larger storage volumes and storage zones are produced by larger and longer lasting fluctuations for a given stream stage hydrograph a lower permeable streambed an aquitard or an anisotropic aquifer of low vertical hydraulic conductivity can significantly reduce the rate of infiltration and limit the size of the storage zone the bank storage solely caused by the stage fluctuation differs slightly between gaining and losing streams short term rainfall recharge and et loss in the shallow groundwater slightly influence on the flow rate but their effects on bank storage in a larger area for a longer period can be considerable

water exchange and pressure transfer between conduits and matrix and their influence on hydrodynamics of two karst aquifers with sinking streams summary karst aquifers are heterogeneous media where conduits usually drain water from lower permeability volumes matrix and fractures for more than a century various approaches have used flood recession curves which integrate all hydrodynamic processes in a karst aquifer to infer physical properties of the movement and storage of groundwater these investigations typically only consider flow to the conduits and thus have lacked quantitative observations of how pressure transfer and water exchange between matrix and conduit during flooding could influence recession curves we present analyses of simultaneous discharge and water level time series of two distinctly different karst systems one with low porosity and permeability matrix rocks in southern france and one with high porosity and permeability matrix rocks in north central florida usa we apply simple mathematical models of flood recession using time series representations of recharge storage and discharge processes in the karst aquifer we show that karst spring hydrographs can be interpreted according to pressure transfer between two distinct components of the aquifer conduit and matrix porosity which induce two distinct responses at the spring water exchange between conduits and matrix porosity successively control the flow regime at the spring this exchange is governed by hydraulic head differences between conduits and matrix head gradients within conduits and the contrast of permeability between conduits and matrix these observations have consequences for physical interpretations of recession curves and modeling of karst spring flows particularly for the relative magnitudes of base flow and quick flow from karst springs finally these results suggest that similar analyses of recession curves can be applied to karst aquifers with distinct physical characteristics utilizing well and spring hydrograph data but information must be known about the hydrodynamics and physical properties of the aquifer before the results can be correctly interpreted

chemical diffusion of major components in granitic liquids implications for the rates of homogenization of crustal melts abstract crustal anatexis coupled with melt extraction and ascent is the main mechanism by which the continental crust differentiates during diffusion controlled melting and in the absence of melt flow and mechanical mixing diffusion is the main process by which the melt phase ultimately homogenizes and mineral residuum and melt equilibrate knowing the diffusive properties of the elements within a granitoid melts is therefore essential for understanding the kinetics and mechanisms of melting as well as the compositions and nature of chemical heterogeneities in granites in this contribution we review a series of experimental studies aimed at an improved understanding of the nature and rates of chemical diffusion of major components of h 2 o saturated granite melts at anatectic conditions in the continental crust the hydrous granite system under investigation makes up 95 99 of natural restite free granitic magmas these experimental results have applications for predicting the composition of granitic liquids during processes such as anatexis magma mixing assimilation or crystallization regarding the diffusive properties the major elements of the liquid can be classified into two categories those whose diffusion is uncoupled with other elements e g si and others whose diffusion is highly coupled with the movement and gradients of other ions e g na and k with h na k ca and h with al one implication of coupled diffusion is that chemical gradients in fast diffusing ions such as na and k may persist for long times in the melt due to their chemical coupling with slow diffusing components such as al the diffusion of components through granitic melts entails two mechanisms local diffusion corresponds to the classical view of chemical diffusion and refers to the relative and random motion of an ion e g si al under apparently local gradients in chemical potential field diffusion corresponds to the long range and coordinated migration of an ionic species e g na driven by a long range chemical potential gradient created by other melt components with which it associates due to coupled diffusion this mechanism serves to erase compositional gradients at rates that are orders of magnitude greater than those by local diffusion this is because the coordinated movement requires individual ions to move only a small fraction of the entire distance over which the chemical potential gradient is established in order to achieve diffusion over distances that may span the entire liquid system the significance and implications of major element diffusivities and the occurrence of coupled diffusion and field diffusion in granitic liquids are highlighted by calculations of the rates of melt homogenization during anatexis of crustal protoliths

quantifying variable rates of postglacial relative sea level fall from a cluster of 24 isolation basins in southern norway abstract sediment sequences obtained from 24 isolation basins located on the skagerrak coastline are used to develop new sea level index points for southern norway the basins are located near a common shoreline isobase and extend from marine limit at c 83 m asl to present sea level the abundance of bedrock isolation basins within the small study area enables a high resolution reconstruction of postglacial relative sea level change for most of the basin records 3 5 samples of terrestrial plant macrofossils were radiocarbon dated across the biostratigraphically defined isolation boundary eight of the isolation events were further constrained by bayesian modelling of the radiocarbon age results the overall reconstructed sea level history is as expected for a formerly glaciated coastline consisting of a rapid regression from marine limit followed by a slower pace of relative sea level fall from early mid holocene to present the new dataset of sea level index points however further delineates century scale oscillations in rates of sea level regression which record past changes in sea surface height and vertical land motion glacial isostatic adjustments gia results provide new constraints for future numerical models aimed at reducing uncertainty in century scale relative sea level projections for fennoscandia

the early mid holocene transgression tapes at the norwegian coast comparing observations with numerical modelling abstract the early to mid holocene transgression dated between approximately 10 000 and 7000 cal yr bp inundated a significant part of the coastal areas of norway in this paper we compare observations of the amplitude of the transgression with numerical modelling the observations of the transgression along the coast vary from a couple of meters to more than 20 m and depend on the distance from the margin of the last ice sheet over fennoscandia we reviewed and evaluated the uncertainty of the data and present here the most reliable observations of the transgression data derived from the analysis of isolation basins from 17 locations spread along the norwegian coast the numerical model simulates the response of the earth to the deglaciation and changing sea level and shows that the transgression is mainly a result of the rising sea level and movements of the earth due to postglacial rebound our earth model consists of two viscous layers overlain by an elastic lithosphere we found a good match to the observations in southern norway with a weak effective elastic lithosphere 30 km this is consistent with a previous study of tilt of the raised late glacial shorelines in southwestern norway in northern norway however the same earth model and ice model give significant mismatch to the observations the best fit model for northern norway has a significantly thicker effective elastic lithosphere an alternative explanation for the mismatch could be a later deglaciation of the barents sea than generally assumed or neo tectonism in the area

hydrological controls of in situ preservation of waterlogged archaeological deposits abstract environmental change caused by urban development land drainage agriculture or climate change may result in accelerated decay of in situ archaeological remains this paper reviews research into impacts of environmental change on hydrological processes of relevance to preservation of archaeological remains in situ it compares work at rural sites with more complex urban environments the research demonstrates that both the quantity and quality of data on preservation status and hydrological and chemical parameters collected during routine archaeological surveys need to be improved the work also demonstrates the necessity for any archaeological site to be placed within its topographic and geological context in order to understand preservation potential fully it is necessary to move away from studying the archaeological site as an isolated unit since factors some distance away from the site of interest can be important for determining preservation the paper reviews what is known about the hydrological factors of importance to archaeological preservation and recommends research that needs to be conducted so that archaeological risk can be more adequately predicted and mitigated any activity that changes either source pathways or the dominant water input may have an impact not just because of changes to the water balance or the water table but because of changes to water chemistry therefore efforts to manage threatened waterlogged environments must consider the chemical nature of the water input into the system clearer methods of assessing the degree to which buried archaeological sites can withstand changing hydrological conditions are needed in addition to research which helps us understand what triggers decay and what controls thresholds of response for different sediments and types of artefact

induced infiltration in aquifers with ambient flow well water quality depends on the relative amounts of water drawn from the pumped aquifer and nearby surface water bodies such as streams lakes and wetlands although a surface water body may normally gain water from the aquifer pumping can reverse gradients causing it to lose water near the well surface water then enters the well by induced infiltration two dimensional vertically integrated models of induced infiltration are developed for various combinations of aquifer geometry and sources of recharge the models which have applications in wellhead protection aquifer pollution characterization and aquifer remediation are presented graphically they show that the propensity for and rate of induced infiltration are enhanced by higher pumping rates proximity of the well to the stream and the presence of nearby barrier boundaries the propensity and rate are reduced by the presence of other surface water bodies ambient groundwater discharge rate to the surface water body also plays a role but not its source whether it is from local vertical recharge lateral inflow or both the results are also largely indifferent to whether the aquifer transmissivity is assumed to be a constant or a function of water table elevation finally if the well is close enough to the surface water body say less than 5 of the aquifer width then the aquifer acts as if it were semi infinite

electrical and hydraulic vertical variability in channel sediments and its effects on streamflow depletion due to groundwater extraction summary the stratification of channel sediments and their vertical hydraulic conductivity kv are important hydrologic information in the analysis of stream aquifer interactions this paper describes the use of direct push technology to generate electrical conductivity ec logs and collect continuous sediment cores beneath river channels the techniques were applied to nine study sites along a 130 km reach of the platte river in southeast nebraska ec logs for the channel surface down to as much as 24 m below the channel surface indicate that the channel sediments in the western part of the reach consist predominantly of sand and gravel low kv silt clay layers occur in the rest of the reach these silt clay layers are either interbedded with sand and gravel or occur as a major unit within the channel sediments as a result the values of kv determined from the sediment cores can vary by four to five orders of magnitude in the same vertical profile of channel sediments at a number of sites the river channel is not lined by a low kv layer at the surface instead the kv values for the top part of channel sediments were consistently greater than kv values for sediments in deeper parts they show a decreasing tendency with the depth this paper also analyzes the effect of low kv layers within channel sediments on streamflow depletion induced by groundwater pumping simulation results suggest that the effectiveness of low kv layers on the calculation of streamflow depletion depends on their depth thickness vertical permeability the length along the channel and the width within the channel as well as the extension into the aquifer on both sides of the river a low kv layer present at the channel surface seems to be the most effective hydrologic feature in reducing the hydrologic connection of stream aquifer a 2008 elsevier b v all rights reserved

relative sea level changes since 15 000 cal yr bp in the nanortalik area southern greenland we present new results for relative sea level change for southern greenland for the interval from 9000 cal yr bp to the present together with earlier work from the same region this yields a nearly complete record from the time of deglaciation to the present isolation and or transgression sequences in one lake and five tidal basins have been identified using lithostratigraphic analyses sedimentary characteristics magnetic susceptibility saturated induced remanent magnetisation sirm organic and carbonate content and macrofossil analyses ams radiocarbon dating of macrofossils and bulk sediment samples provides the timescale relative sea level fell rapidly and reached present day level at similar to 9300 cal yr bp and continued falling until at least 9000 cal yr bp between 8000and6000cal yrbpsea level reached its lowest level of around similar to 10m below highest astronomical tide at around 5000 cal yr bp sea level had reached above 7 8 m below highest astronomical tide and slowly continued to rise not reaching present day sea level until today the isostatic rebound caused rapid isolation of the basins that are seen as distinct isolation contacts in the sediments in contrast the late holocene transgressions are less well defined and occurred over longer time intervals the late holocene sea level rise may be a consequence of isostatic reloading by advancing glaciers and or an effect of the delayed response to isostatic rebound of the laurentide ice sheet one consequence of this transgression is that settlements of palaeo eskimo cultures may be missing in southern greenland copyright c 2006 john wiley sons ltd

implications of equilibrium and disequilibrium among crystal phases in the bishop tuff eruption of the bishop tuff magma preserved equilibrium of exchange components and element concentrations among magnetite ilmenite biotite apatite zircon and liquid orthopyroxene and clinopyroxene were not in exchange equilibrium with the other mgfe bearing phases but they appear to have been in equilibrium among themselves internally consistent temperatures recorded by the feti oxide ti in quartz and 18 o quartz magnetite thermometers coupled with evidence for magmatic corrosion of quartz and sanidine indicate that an initially low t 700 c near h 2 o saturated high sio 2 rhyolite magma was heated up to 800 c and its crystal cargo partially melted by recharge of hotter melt from below oxygen fugacity and compositions of biotite ilmenite magnetite and silicate liquid initially adjusted by internal rearrangement of components and conservation of oxygen partial melting of feldspars liberated sr and ba back into the melt mixing during recharge eventually re introduced compatible elements e g mg ba sr as well as foreign crystals of euhedral ortho and clinopyroxene which evidently never totally re equilibrated with the rhyolite liquid introduction of co 2 and accompanying reduction in the a h 2 o during recharge raised crystallization temperatures of quartz and sanidine in the rhyolite sufficient to allow marginal regrowth of these phases with enhanced contents ti ba and sr

assimilation and crystal accumulation in a mid crustal magma chamber the sausfjellet pluton north central norway the sausfjellet pluton is made up of two intrusive units emplaced into high grade metamorphic rocks of the helgeland nappe complex of the uppermost allochthon in the norwegian caledonides the eastern part of the pluton intruded marble and less voluminous calc silicate and pelitic rocks the western half is hosted predominantly by semi pelitic migmatite with intercalated marble remelting of the migmatite during pluton emplacement occurred in a thermal aureole as much as 1000 m wide the early gabbroic unit forms the southeastern part of the body it consists of hornblende bearing to hornblende rich gabbro and diorite which is thought to have crystallized from an h2o rich andesitic parental magma the younger dioritic unit underlies the central and western parts of the pluton as well as a zone as much as 200 m wide that separates the rest of the pluton from its host rocks herein the annular zone the interior or central zone of the dioritic unit is pyroxene diorite that is locally interlayered with anorthosite the western and annular zones are by comparison mineralogically heterogeneous they range from diorite to quartz monzonite and from biotite bearing two and threepyroxene assemblages to biotite hornblende assemblages neither rock type nor mafic assemblage is correlated with position in the pluton or proximity to a contact stoped blocks of a distinctive coarse grained diorite as well as pyroxenerich calc silicates are present in the gabbroic unit and the central zone of the dioritic unit the few stoped blocks observed in the western zone of the dioritic unit are predominantly quartz rich gneiss chemical variation in the central zone of the dioritic unit is interpreted to result from accumulation of pyroxenes plagioclase from an h2o poor andesitic parent these rocks have approximately constant d 18 o of 6 6f0 2x and lack evidence of in situ assimilation heterogeneities in the western and annular zones of the dioritic unit are reflected in variable anomalously enriched incompatible element contents and in d 18 o which ranges from 6 7x to 8 6x petrologic models indicate that the magma parental to the central zone could also be parental to the western and annular zones if so evolution of the western and annular zone magma was by crystal accumulation and assimilation of metapelitic host rocks as much as 20 of the mass of the western and annular zones can be ascribed to assimilated material which apparently entered the magma by stoping therefore the asymmetrical

kinetics of anorthite dissolution in basaltic melt abstract we report convection free anorthite dissolution experiments in a basaltic melt at 1280 1500 c and 0 5 gpa on two different crystallographic surfaces 1 2 1 and 3 0 2 to investigate dissolution kinetics the anisotropy of the anorthite dissolution rate along these two surfaces is negligible time series experiments at 1280 c show that anorthite dissolution is mainly controlled by diffusion in the melt within experimental uncertainty analytical solutions were used to model the dissolution and diffusion processes and to obtain the diffusivities and the saturation concentrations of the equilibrium determining component al2o3 for anorthite dissolution into the basaltic melt for the first time we are able to show the physical and chemical characteristics of quench growth effect on the near interface melt using high spatial resolution 0 3 m eds analyses for anorthite an 90 saturation in a melt with 39 53 wt sio2 and 0 4 wt h2o the concentration of al2o3 in wt depends on temperature as follows ln c s al 2 o 3 8 032 0 192 7882 287 t where t is temperature in k and errors are given at 1 level al2o3 diffusivity in basaltic melt during plagioclase dissolution can be expressed as ln d al 2 o 3 ebd plag diss 13 69 1 57 19 313 2485 t where d is in m2 s and the activation energy is 161 21 kj mol these results are applied to model the convective dissolution of anorthite in basaltic melts the model indicates that though anorthite crystals can survive for a longer time compared to olivine crystals of the same size in the same melt the former would rise for a much smaller distance compared to the olivine sinking distance due to the smaller density contrast between anorthite and melt

traces of tsunami preserved in inter tidal lacustrine and marsh deposits some examples from northeast japan the japan sea earthquake of may 26 1983 triggered a large scale tsunami that surged over the coast of ne japan and caused considerable damage the tsunami resulted in peculiar sedimentary processes on the coast depending on the hydraulic scale of the tsunami three kinds of sedimentary processes were recognized each of which left unique deposits such deposits are expected to remain in sedimentary sequences preserving remarkable sedimentary facies borehole samples drilled at different localities in coastal regions have been examined to detect traces of ancient tsunamis sedimentological and geochemical studies of the samples reveal that layered deposits similar to those developed by the tsunami of the japan sea earthquake are common in the drilled cores estimated ages of these deposits are exactly equivalent to the dates of ancient tsunamis documented in historical records these results show that the invasion of tsunamis is recorded in coastal depositional sequences from analyses of long borehol

solute transport processes in flow event driven stream aquifer interaction the interaction between streams and groundwater controls key features of the stream hydrograph and chemograph since surface runoff is usually less saline than groundwater flow events are usually accompanied by declines in stream salinity in this paper we use numerical modelling to show that at any particular monitoring location i the increase in stream stage associated with a flow event will precede the decrease in solute concentration arrival time lag for solutes and ii the decrease in stream stage following the flow peak will usually precede the subsequent return increase in solute concentration return time lag both arrival time lag and return time lag increase with increasing wave duration however arrival time lag decreases with increasing wave amplitude whereas return time lag increases furthermore while arrival time lag is most sensitive to parameters that control river velocity channel roughness and stream slope return time lag is most sensitive to groundwater parameters aquifer hydraulic conductivity recharge rate and dispersitivity additionally the absolute magnitude of the decrease in river concentration is sensitive to both river and groundwater parameters our simulations also show that in stream mixing is dominated by wave propagation and bank storage processes and in stream dispersion has a relatively minor effect on solute concentrations this has important implications for spreading of contaminants released to streams our work also demonstrates that a high contribution of pre event water or groundwater within the flow hydrograph can be caused by the combination of in stream and bank storage exchange processes and does not require transport of pre event water through the catchment

distinction between the storegga tsunami and the holocene marine transgression in coastal basin deposits of western norway many coastal lakes were inundated by both the storegga tsunami 7000 14 cy r bp and the mid holocene sea level rise the tapes transgression in western norway the tsunami eroded lake bottoms and deposited graded and or massive beds of sand rip up clasts and coarse plant material by contrast when the rising sea entered the lakes it deposited only gyttja silt and fine sand without causing much erosion of the underlying lake sediments storegga tsunami deposits in some coastal lakes were interpreted previously as ordinary marine sediments from the tapes transgression our reinterpretation of these deposits shows that the transgression maximum phase was reached after 6500 yr bp more than 1000 yr later than previously inferred for the coast of sunnmore the new data cannot be combined in a shoreline diagram without showing the 6000 yr bp and 7000 yr bp shorelines as slightly warped 1998 john wiley sons ltd

the holocene storegga slide tsunami in the united kingdom all currently known sites in the united kingdom with evidence for the holocene storegga slide tsunami are described information on the altitude distribution stratigraphical context age particle size profile and microfossil characteristics of the deposits is presented the tsunami involved a greater area than previously described reaching a coastline over 600 km long the ubiquitous sand layer which forms the main deposit associated with the event is shown to exhibit a consistent morphology and a particle size profile marked by fining upwards sequences an analysis of new and previously published radiocarbon dates indicates that from evidence in the united kingdom the event took place sometime around 7100 radiocarbon years bp 7900 calibrated years bp a new isobase model for mainland scotland and adjacent areas providing a preliminary estimate of land uplift since the tsunami is presented the model estimates contemporary sea surface level offshore at 14 m below the present day mean high water spring tides tsunami sediment run up is greatest in inlets where it reaches at least 25 m on shetland and at least 5 m along the mainland coastline to the south and run up of the tsunami would have exceeded these values the tsunami sediments identified here are considered particularly valuable as a synchronous marker horizon

convective crystal dissolution the effect of free and forced convection on crystal dissolution is examined both theoretically and experimentally well established relationships for heat and mass transfer are applied to obtain approximate expressions for the dissolution velocity and the associated thickness of the compositional boundary layer these expressions are found to be in good agreement with experimental observations of the dissolution of quartz crystals in basalt and nacl crystal in water when applied to light felsic crystals in basaltic magmas the expressions predict that forced convection will produce a boundary layer thickness of about 100 m and a dissolution velocity of order 10 6 cm s 1 these velocities are too slow for xenocrysts to be dissolved significantly during magma ascent in dykes but are sufficient for cm size crystals to dissolve in the interior of a convecting magma chamber larger crystals are likely to accumulate at the chamber s roof where free convection is predicted to dissolve them at velocities of order 10 7 cm s 1 in an appendix the dissolution of the chamber s walls is also considered and a velocity of order 10 8cm s 1 is predicted

groundwater flow in sloping aquifer under localized transient recharge analytical study abstractthis paper analyzes the groundwater flow system in an unconfined downward sloping aquifer of semi infinite extent in response to localized transient recharge the aquifer is in contact with a water body of constant water level at one end and receives localized transient recharge from a recharge basin of finite width the mathematical model is based on the boussinesq equation with dupuit forchheimer assumption in which the spatial coordinate of the recharge basin is treated as an additional parameter analytical solutions of the linearized boussinesq equation are obtained using the laplace transform technique by dividing the aquifer in a three zone system containing both dirichlet and neumann boundary conditions at the hypothetical interfaces upward and zero sloping cases are deduced from the main results by appropriately adjusting the slope parameter to assess the validity and efficiency of the linearization method the nonlinear boussinesq equation is also solved using a fully explicit predic

coastal sedimentation associated with the december 26 2004 tsunami in lhok nga west banda aceh sumatra indonesia abstract with wave heights of 30 m and runups reaching 50 m a s l and 6 km inland the december 26 2004 tsunami in sumatra was one of the largest tsunamis in recorded human history in this paper we present a description of the event in the lhok nga bay west coast of banda aceh and an interpretation of the tsunami sand deposits mostly based upon grain size analysis the 3 5 km long transect of lampuuk displays two landward fining thinning and sorting sequences the thickest cross sections of the first sequence of deposits 0 1 5 km inland suggest a deposition by three consecutive runups inflows and a final backwash return flow or outflow from 1 5 to 3 5 km inland the record is dominated by the second and highest wave 15 30 m normally graded couplets or triplets of layers were used to identify the runup of each wave the topmost layers interpreted as the backwash deposition describe a seaward sequence of increasing mean grain size and decreasing degree of sorting the local effects of the topography could be identified thickest deposits in the topographic lows 50 80 cm great spatial variations in thickness and upper laminated texture when the sedimentation was limited by steep slopes landward coarsening and very poor sorting at the wave breaking point bimodal grain size distributions reflecting different sources of sediments finally by coupling the longitudinal and vertical trends of the 26 cross sections we propose a model of sediment transport and deposition in a large tsunami wave

groundwater dynamics due to general stream fluctuations in an unconfined single or dual porosity aquifer subjected to general areal recharge abstract analytical solutions of groundwater dynamics in an elongated aquifer subjected to general time dependent recharge are presented the lateral boundaries are specified heads with the head variations governed by general time dependent functions general recharge function was not considered in previous works of this kind both single and double porosity aquifers are considered the solution is obtained using fourier sine and laplace transformations followed by an inverse fourier laplace transform involving residue theorem and convolutional integral for the unconfined single porosity aquifer case the exact time domain solution is obtained using the residue theorem for the unconfined double porosity aquifer case the time domain head is calculated using the de hoog inverse laplace algorithm the presented solution can be used to estimate the hydraulic parameters of 1 groundwater head variation of a river basin aquifer subjected to general lateral head variation and recharge 2 groundwater head variation in a double porosity elongated fractured anticline 3 groundwater depletion of an elongated fractured anticline subjected to recharge due to rainfall or snowmelt to its adjacent alluvial aquifer in addition the presented solution can be utilized to optimize the irrigation pattern in a cropland between two trench drains to control the groundwater mound

dissolution of quartz albite and orthoclase in h2o saturated haplogranitic melt at 800 c and 200 mpa diffusive transport properties of granitic melts at crustal anatectic conditions we have conducted experiments on dissolution of quartz albite orthoclase and corundum into h2o saturated haplogranite melt at 800 c and 200mpa over a duration of 120 1488h with the aim of ascertaining the diffusive transport properties of granitic melts at crustal anatectic temperatures cylinders of anhydrous starting glass and a single mineral phase quartz or feldspar were juxtaposed along flat and polished surfaces inside gold or platinum capsules with 10 wt added h2o concentration profiles in glass quenched melt perpendicular to the mineral glass interfaces and comparison with relevant phase diagrams suggest that melts at the interface are saturated in the dissolving phases after 384h and with longer durations the concentration profiles are controlled only by diffusion of components in the melt the evolution of the concentration profiles with time indicates that uncoupled diffusion in the melt takes place along the following four linearly independent directions in oxide composition space sio2 n a2o and k2o axes si na and k eigenvectors respectively and a direction between the al2o3 na2o and k2o axes al eigenvector such that the al na molar ratio is equal to that of the bulk melt and the al na k molar ratio is equal to the equilibrium asi mol al2o3 na2o k2o of the melt experiments in which a glass cylinder was sandwiched between two mineral cylinders quartz and albite quartz and k feldspar or albite and corundum tested the validity of the inferred directions of uncoupled diffusion and explored longrange chemical communication in the melt via chemical potential gradients the application of available solutions to the diffusion equations for the experimental quartz and feldspar dissolution data provides diffusivities along the directions of the si eigenvector and al eigenvector of 2 0 2 8 10 15 m 2 s and 0 6 2 4 10 14 m 2 s respectively minimum diffusivities of alkalis 3 9 10 11 m 2 s are orders of magnitude greater than the tetrahedral components of the melt the information provided here determines the rate at which crustal anatexis can occur when sufficient heat is supplied and diffusion is the only mass transport mixing process in the melt the calculated diffusivities imply that a quartzo feldspathic source rock with initial grain size of 2 3mm undergoing hydrostatic h2o saturated melting at 800 c infinite heat supply could produce 20 30 vol of homogeneous melt in less than 1 10 years slower diffusion in h2o undersaturated melts will increase this time frame

time scales of magmatic processes new insights from dynamic models for magmatic assimilation we present a computational model that predicts the consequences of time dependent isenthalpic assimilation fractional crystallization afc our model combines an existing paradigm for fractional crystallization based on equilibrium thermodynamics with a kinetic model for predicting rates of mineral dissolution the isenthalpic constraint directly links the sensible heat of the magma and the latent heat of crystallization to the energy necessary for assimilation thus we predict liquid lines of descent rates of crystallization rates of cooling and ratios of assimilation to crystallization r as a function of time model simulations predict the time scale of afc processes weeks to years and show the extent to which temperature and composition of the assimilant control these time scales

dynamic ice formation in channels as a driver for stream aquifer interactions 1 this research introduces and provides evidence of a novel mechanism of stream aquifer exchange caused by dynamic ice formation on streams at a stream site in southwestern wisconsin we document a significant fluctuation in stream depth and the potentiometric surface in the adjacent aquifer during periods of ice formation suggesting that stream aquifer interactions may be influenced by these transient events four years of winter stream data document that dynamic ice formation 1 causes an average increase in stream depth of 106 2 affects stream depth on 20 of days from december through february and 3 substantially alters stream aquifer interactions by reducing the hydraulic gradient toward the channel during ice formation events dynamic ice formation represents a potentially widespread mechanism for altering stream aquifer interactions and associated biogeochemical transformations the sensitivity of this process to air temperature indicates a need for further research on the impacts of climate warming

some giant submarine landslides do not produce large tsunamis landslides are the second most important cause of tsunamis after earthquakes and their potential for generating large tsunamis depend on the slide process among the world s largest submarine landslides is the storegga slide that generated an ocean wide catastrophic tsunami while no traces of a tsunami generated from the similar and nearby traenadjupet slide have been found previous models for such landslide tsunamis have not been able to capture the complexity of the landslide processes and are at odds with geotechnical and geomorphological data that reveal retrogressive landslide development the tsunami generation from these massive events are here modeled with new methods that incorporate complex retrogressive slide motion we show that the tsunamigenic strength is closely related to the retrogressive development and explain for the first time why similar giant landslides can produce very different tsunamis sometimes smaller than anticipated because these slide mechanisms are common for submarine landslides modeling procedures for dealing with their associated tsunamis should be revised

propagation of the storegga tsunami into ice free lakes along the southern shores of the barents sea this paper is part of anders romundset s doctoral thesis which is available in munin at http hdl handle net 10037 2703

aquifer response to stream stage and recharge variations ii convolution method and applications abstract in this second of two papers analytical step response functions developed in the companion paper for several cases of transient hydraulic interaction between a fully penetrating stream and a confined leaky or water table aquifer are used in the convolution integral to calculate aquifer heads streambank seepage rates and bank storage that occur in response to stream stage fluctuations and basinwide recharge or evapotranspiration two computer programs developed on the basis of these step response functions and the convolution integral are applied to the analysis of hydraulic interaction of two alluvial stream aquifer systems in the northeastern and central united states these applications demonstrate the utility of the analytical functions and computer programs for estimating aquifer and streambank hydraulic properties recharge rates streambank seepage rates and bank storage analysis of the water table aquifer adjacent to the blackstone river in massachusetts suggests that the very shallow depth of water table and associated thin unsaturated zone at the site cause the aquifer to behave like a confined aquifer negligible specific yield this finding is consistent with previous studies that have shown that the effective specific yield of an unconfined aquifer approaches zero when the capillary fringe where sediment pores are saturated by tension extends to land surface under this condition the aquifer s response is determined by elastic storage only estimates of horizontal and vertical hydraulic conductivity specific yield specific storage and recharge for a water table aquifer adjacent to the cedar river in eastern iowa determined by the use of analytical methods are in close agreement with those estimated by use of a more complex multilayer numerical model of the aquifer streambank leakance of the semipervious streambank materials also was estimated for the site the streambank leakance parameter may be considered to be a general or lumped parameter that accounts not only for the resistance of flow at the river aquifer boundary but also for the effects of partial penetration of the river and other near stream flow phenomena not included in the theoretical development of the step response functions

a semi analytical generalized hvorslev formula for estimating riverbed hydraulic conductivity with an open ended standpipe permeameter the well known hvorslev 1951 formula was developed to estimate soil permeability using single well slug tests and has been widely applied to determine riverbed hydraulic conductivity using in situ standpipe permeameter tests here we further develop a general solution of the hvorslev 1951 formula that accounts for flow in a bounded medium and assumes that the bottom of the river is a prescribed head boundary the superposition of real and imaginary disk sources is used to obtain a semi analytical expression of the total hydraulic resistance of the flow in and out of the pipe as a result we obtained a simple semi analytical expression for the resistance which represents a generalization of the hvorslev 1951 the obtained expression is benchmarked against a finite element numerical model of 2 d flow in r z coordinates in an anisotropic medium the results exhibit good agreement between the simulated and estimated riverbed hydraulic conductivity values furthermore a set of simulations for layered stochastically heterogeneous riverbed sediments was conducted and processed using the proposed expression to demonstrate the potential associated with measuring vertical heterogeneity in bottom sediments using a series of standpipe permeameter tests with different lengths of pipe inserted into the riverbed sediments

double porosity models for a fissured groundwater reservoir with fracture skin theories of flow to a well in a double porosity groundwater reservoir are modified to incorporate effects of a thin layer of low permeability material or fracture skin that may be present at fracture block interfaces as a result of mineral deposition or alteration the commonly used theory for flow in double porosity formations that is based upon the assumption of pseudo steady state block to fissure flow is shown to be a special case of the theory presented in this paper the latter is based on the assumption of transient block to fissure flow with fracture skin under conditions where fracture skin has a hydraulic conductivity that is less than that of the matrix rock it may be assumed to impede the interchange of fluid between the fissures and blocks resistance to flow at fracture block interfaces tends to reduce spatial variation of hydraulic head gradients within the blocks this provides theoretical justification for neglecting the divergence of flow in the blocks as required by the pseudo steady state flow model coupled boundary value problems for flow to a well discharging at a constant rate were solved in the laplace domain both slab shaped and sphere shaped blocks were considered as were effects of well bore storage and well bore skin resultsmore obtained by numerical inversion were used to construct dimensionless type curves that were applied to well test data for a pumped well and for an observation well from the fractured volcanic rock terrane of the nevada test site less

transient solution for stream unconfined aquifer interaction due to time varying stream head and in the presence of leakage summary this paper presents new analytical solutions of a linearized boussinesq equation characterizing groundwater flow in a stream unconfined aquifer system due to transient seepage the aquifer is underlain by a horizontal leaky bed and interacts with an adjoining stream of varying water level through a semipervious vertical stream bank close form analytical expressions are derived to predict water head distribution flow rate and volumetric exchange of water in response to time dependent rise or drop in the stream water level comparison between analytical and numerical results shows satisfactory agreement the effects of the finite and semi infinite lengths of the domain are considered in detail certain asymptotic situations such as sudden rise or drop in the stream water level no flow condition at the aquifer s base and absence of vertical stream bank can be dealt with as limiting cases of main results an illustration of the new analytical approach is used to quantify the accretion recession of the bank storage due to variation in various aquifer parameters

modeling of gas driven magmatic overturn tracking of phenocryst dispersal and gathering during magma mixing 1 we present a combined multiphase numerical and crystal tracking approach that provides a framework to investigate the transport and zoning of crystals associated with a gas driven mixing event mixing in compositionally intermediate to silicic magmatic systems is often initiated by gas exsolution in the recharging magma causing a density inversion and subsequent overturn the overturn is simulated for a range of bubble volume fractions bubbles and therefore indirectly for a range of reynolds numbers re all simulations show chaotic flow dynamics with fast overturn timescales of minutes to hours the large scale mixing is inefficient during a single overturn resulting in a continuously stratified system with respect to bubble volume fraction the crystal tracking algorithm provides us with information on the small scales i e 10 cm on this length scale we observe gathering of different crystals during the overturn that typically ranges on the order of tens of meters thus a complex crystal population may arise within a single overturn this gathering and dispersal of crystals is strongest and most uniform for high re for low re crystal populations are characterized by less gathering of crystals that originated from distal portions of the magma body during the overturn the crystals pass through environments of changing chemical potential we apply the damkohler number da which compares the crystallization or dissolution to the advection timescale results show an asymmetry between crystallization and dissolution crystallization times are too slow during gas driven overturn to record transient changes in chemical potential crystals most likely only record their initial as well as their final chemical environment in contrast dissolution and advection rates are of similar order suggesting potential dissolution during the overturn on the basis of the results for gas driven overturn we expect that slower physical mixing processes may be continuously recorded in the zonation pattern of the crystal phases as long as the changes in chemical potential produce crystal growth

mediterranean flash flood transfer through karstic area karstic aquifers influence flash floods propagation in mediterranean countries near montpellier southern france discharge data are recorded on the coulazou river upstream and downstream of the aumelas causse two gauging stations are used to describe the hydrodynamics of this binary karstic system the first station characterizes the non karstic catchment area the second one is representative of the karstic part of the watershed records since april 2004 are used to understand how the river interacts with a karstic aquifer hydrograph analysis of three flash flood events is described corresponding discharge time series recorded at the two gauging stations are used to describe the modification of the hydrographs by auto and crosscorrelations analyses finally linear system analyses are used to provide the transfer functions of this binary karstic system according to the three flood events characteristics initial conditions volume spatial distribution of rainfall etc theses functions summarize the hydrodynamic behaviour of the system their shapes are indicative of the dynamics of the storage the release and the contribution to surface waters

buseckite fe zn mn s a new mineral from the zaklodzie meteorite buseckite ima 2011 070 fe zn mn s is the fe dominant analog of wurtzite a new member of the wurtzite group discovered in zaklodzie and an ungrouped enstatite rich achondrite the type material occurs as single crystal grains 4 20 m in size in contact with two or more of enstatite plagioclase troilite tridymite quartz and sinoite low ni iron martensitic iron schreibersite keilite cristobalite and graphite which are also present in the type sample are not observed to be in contact with buseckite buseckite is black under diffuse illumination and nearly opaque grayish brown in transmitted light the mean chemical composition of buseckite as determined by electron microprobe analysis of the type material is wt s 35 84 fe 28 68 zn 23 54 mn 10 04 mg 1 18 sum 99 28 leading to an empirical formula calculated on the basis of 2 atoms of fe 0 46 zn 0 32 mn 0 16 mg 0 04 0 99 s 1 01 electron backscatter diffraction patterns of buseckite are a good match to that of synthetic zn 0 558 fe 0 442 s with the p6 3mc structure showing a 3 8357 c 6 3002 a v 80 27 a3 and z 2 buseckite is likely derived from the breakdown of high temperature pyrrhotite to form troilite and buseckite following the solidification of sulfide rich liquids produced during impact melting of an enstatite rich rock

propagation of solutes and pressure into aquifers following river stage rise 1 water level rises associated with river flow events induce both pressure and solute movement into adjacent aquifers at vastly different rates we present a simple analytical solution that relates the travel time and travel distance of solutes into an aquifer following river stage rise to aquifer properties combination with an existing solution for pressure propagation indicates that the ratio of solute to pressure travel times is proportional to the ratio of the volume of water stored in the aquifer before the river stage rise and the volume added by the stage rise and is independent of hydraulic conductivity two dimensional numerical simulations of an aquifer slice perpendicular to a river demonstrate that the solutions are broadly applicable to variably saturated aquifers and partially penetrating rivers the solutions remain applicable where river stage rise and fall occur provided that regional hydraulic gradients are low and the duration of the river stage rise is less than pressure and solute travel times to the observation point in the aquifer consequently the solutions provide new insight into the relationships between aquifer properties and distance and time of solute propagation and in some cases may be used to estimate system characteristics travel time metrics obtained for a flood event in the cockburn river in eastern australia using electrical conductivity measurements enabled estimates of aquifer properties and a lateral extent of river aquifer mixing of 25 m a detailed time series of any soluble tracer with distinctly different concentrations in river water and groundwater may be used

divergence and flow direction as indicators of subsurface heterogeneity and stage dependent storage in alluvial floodplains assuming homogeneity in alluvial aquifers is convenient but limits our ability to accurately predict stream aquifer interactions research is needed on i identifying the presence of focused as opposed to diffuse groundwater discharge recharge to streams and ii the magnitude and role of large scale bank and transient storage in alluvial floodplains relative to changes in stream stage the objective of this research was to document and quantify the effect of stage dependent aquifer heterogeneity and bank storage relative to changes in stream stage using groundwater flow divergence and direction monitoring was performed in alluvial floodplains adjacent to the barren fork creek and honey creek in northeastern oklahoma based on results from subsurface electrical resistivity mapping observation wells were installed in high and low electrical resistivity subsoils water levels in the wells were recorded real time using pressure transducers august to october 2009 divergence was used to quantify heterogeneity i e variation in hydraulic conductivity porosity and or aquifer thickness and flow direction was used to assess the potential for large scale 100 m bank or transient storage areas of localized heterogeneity appeared to act as divergence zones allowing stream water to quickly enter the groundwater system or as flow convergence zones draining a large groundwater area maximum divergence or convergence occurred with maximum rates of change in flow rates or stream stage flow directions in the groundwater changed considerably between base and high flows suggesting that the floodplains acted as large scale bank storage zones rapidly storing and releasing water during passage of a storm hydrograph during storm events at both sites the average groundwater direction changed by at least 90 from the average groundwater direction during baseflow aquifer heterogeneity in floodplains yields hyporheic flows that are more responsive and spatially and temporally complex than would be expected compared to more common assumptions of homogeneity copyright 2012 john wiley sons ltd

estimates of south greenland late glacial ice limits from a new relative sea level curve abstract marine lacustrine isolation contacts from seven basins in the nanortalik area south greenland have been analysed and dated the basins were isolated from the sea as a consequence of isostatic rebound following deglaciation the isolation contacts were identified with litho and biostratigraphical analyses especially sedimentary changes grey scale analyses and analyses of macroscopical remains of plants and animals dating was performed by analytical mass spectroscopy radiocarbon dating of macrofossils and bulk sediment samples a slow initial relative sea level fall that begins at 13 8 cal ka bp changes to a rapid relative sea level fall before the sea level fell below the present day sea level just prior to 10 cal ka bp the emergence curve goes further back in time than any previous emergence curve constructed from greenland which reflects the early deglaciation of the studied region the glacio isostatic crustal rebound following deglaciation was around 110 m the sea level history indicates that the margin of the greenland ice sheet probably extended out to the shelf margin during the last glacial maximum and that the ice thickness must have been at least 1500 m over the outer coast thus the highest coastal mountains would have been ice covered which is surprising given their alpine character in addition the major part of the recession of the ice must have occurred relatively late and quickly maybe from 14 to 12 cal ka bp the late holocene transgression may at least in part be due to increased isostatic loading as a consequence of advancing glaciers during the neoglaciation

relative sea level changes during the holocene in the sisimiut area south western greenland holocene relative sea level rsl changes have been investigated by analysing and dating isolation sequences from five lakes near sisimiut in south western greenland the transitions between marine and lacustrine sediments were determined from elemental analyses and analyses of macroscopic plant and animal remains radiocarbon dating was used to provide minimum ages for the transitions and to construct a rsl curve dating of a shell of the marine bivalve macoma balthica indicates that deglaciation of the lowlands occurred in the early holocene at around 10 900 cal a bp the rsl curve shows initial rapid regression from the marine limit at around 140 m implying strong glacio isostatic rebound we suggest that the margin of the greenland ice sheet was located at the shelf break during the last glacial maximum frequent remains of the ostracode sarcypridopsis aculeata which is a thermophilous brackish water species that is unknown from the extant fauna of greenland in one of the basins around 8500 cal a bp may mark the beginning of the holocene thermal maximum in the region copyright 2011 john wiley sons ltd

hydrogeology of a complex champlain sea deposit quebec canada implications for slope stability the thick sequences of marine clayey deposits which blanket the st lawrence lowlands in south eastern canada are highly susceptible to landslides with 89 of the population of the province of que