reinterpretation of the burmester core bonneville basin utah abstract initial interpretation of the sediments from the burmester core eardley et al 1973 geological society of america bulletin 84 211 216 indicated that 17 deep lake cycles separated by shallow lake and soil forming intervals occurred in the bonneville basin during the brunhes chron the last 780 10 3 yr our re examination of the core along with new sedimentological geochronological and paleontological data indicate that only four deep lake cycles occurred during this period apparently correlative with marine oxygen isotope stages 2 6 12 and 16 this interpretation suggests that large lakes formed in the bonneville basin only during the most extensive of the northern hemisphere glaciations

insolation values for the climate of the last 10 million years new values for the astronomical parameters of the earth s orbit and rotation eccentricity obliquity and precession are proposed for paleoclimatic research related to the late miocene the pliocene and the quaternary they have been obtained from a numerical solution of the lagrangian system of the planetary point masses and from an analytical solution of the poisson equations of the earth moon system the analytical expansion allows the direct determination of the main frequencies with their phase and amplitude numerical and analytical comparisons with the former astronomical solution ber78 are performed so that the accuracy and the interval of time over which the new solution is valid can be estimated the corresponding insolation values have also been computed this analysis leads to the conclusion that the new values are expected to be reliable over the last 5 ma in the time domain and at least over the last 10 ma in the frequency domain

contributions of la nina and el nino to middle holocene drought and late holocene moisture in the american southwest eolian landforms in estancia basin central new mexico record two episodes of extreme drought and low groundwater levels during the middle holocene 7000 5400 1 4 c yr b p followed by a rise in the water table throughthe late holocene blowouts and associated lunettes formed when water levels fell below the desiccated floor of pluvial lake estancia allowing widespread deflation elevation of the water table in the basin is regulated by a balance between evaporation from playas that occupy the blowouts and recharge of aquifers in the adjacent manzano mountains isotopic analyses of modern precipitation and groundwater reveal that recharge originates primarily as winter moisture which is amplified during el ninos and diminished during la ninas thus changes in the elevation of a reconstructed holocene water table may reflect systematic changes in el nino southern oscillation enso circulation

the baseflow and storm flow hydrology of a precambrian shield headwater peatland a hydrological investigation was conducted in a small headwater peatland located in the experimental lakes area north western ontario canada to determine the subsurface and surface flow paths within the peatland and between the peatland and an adjacent forested upland during baseflow and storm flow conditions distinct zones of groundwater recharge and discharge were observed within the peatland these zones are similar to those found in much larger flow systems even though the peatland was only influenced by local groundwater flow groundwater emerging in seeps and flowing beneath the peatland sustained the surface wetness of the peatland and maintained a constant baseflow the response of the peatland stream to summer rain events was controlled by peatland water table position when the basin was dry and antecedent moisture storage on the uplands when the basin was wet the magnitude and timing of peak runoa during wet conditions were controlled by the degree of hydrological connectivity between the surrounding upland terrain and the peatland 1998 john wiley sons ltd hydrol process vol 12 57 72 1998

regional groundwater modeling of the yucca mountain site using analytic elements abstract two of the complicating factors in modeling the regional groundwater flow at yucca mountain are the large distance to hydrogeologic boundaries and the large thickness of the aquifer the hydrogeologic boundaries are up to 500 km away from yucca mountain and the aquifer is up to 5000 m thick the distant hydrogeologic boundaries may be taken into account explicitly by application of the analytic element method which is applied to a model of this size for the first time in this study the analytic element method makes it possible to include distant hydrogeologic boundaries and at the same time allows for local detail without the excessive computational effort that would be required with the finite difference method regional flow in the aquifer is modeled with a single layer based on a theoretical argument and supported by the model results the match between simulated and measured heads is similar to that of previous finite difference models of parts of the region these previous studies consist of multiple layers and include inferred boundary conditions head or flux specified along most of the boundary of the domain

the hydrological function of upland swamps in eastern australia the role of geomorphic condition in regulating water storage and discharge abstract temperate highland peat swamps on sandstone thpss are a type of wetland found in low order streams on the plateaus of eastern australia they are sediment and organic matter accumulation zones which combined with a climate of high rainfall and low evaporation function as water storage systems changes to the geomorphic structure of these systems via incision and channelisation can have profound impacts on their hydrological function the aim of this study was to develop an understanding of how changes to the geomorphic structure of these systems alter their hydrological function measured as changes and variability in swamp water table levels and discharge we monitored the water table levels and discharges of three intact and three channelised thpss in the blue mountains between march 2015 and june 2016 we found that water levels in intact swamps were largely stable over the monitoring period water levels rose only in high rainfall events returned quickly to antecedent levels after rain and drawdown during dry periods was not significant in contrast the water table levels in channelised thpss were highly variable water levels rose quickly after almost all rainfall events and declined significantly during dry periods discharge also showed marked differences with the channelised thpss discharging 13 times more water than intact swamps even during dry periods channelised thpss also had flashier storm hydrographs than intact swamps these results have profound implications for the capacity of these swamps to act as water storage reservoirs in the headwaters of catchments and for their ability to maintain base flow to downstream catchments during dry times changes to geomorphic structure and hydrological function also have important implications for a range of other swamp functions such as carbon storage emission and exports contaminant sorption downstream water quality and biodiversity as well as the overall fate of these swamps under a changing climate

the influence of hyporheic exchange on reach scale water budgets in a precambrian shield catchment quebec canada the influence of hyporheic exchange on water and solute budgets of streams is widely identified as important yet there is a notable absence of research identifying its role in precambrian shield headwater streams this research addressed this shortcoming by quantifying the proportions of solute mass loss net and gross water gains and losses for selected reaches over a single summer recession period six conservative tracer injections were performed on nine reaches of a 2 94 km2 catchment in gatineau park quebec canada from july to november 2011 high solute exchange occurred for all reaches despite most showing positive net discharge solute losses in stream reaches typically exceeded 10 and substantial gross water losses and gains indicate a high degree of bi directional water exchange along stream reaches both solute loss and the fraction of channel water involved in hyporheic exchange increased throughout the summer in response to a decrease in discharge and increase in the time of contact results support the assertion that reductions in groundwater contributions to streamflow throughout the summer baseflow period allow for greater exchange of water through hyporheic flowpaths which constitute the majority of gross channel losses and gains spatial inter reach variability in mass loss has been previously ascribed to watershed control on exchange potential in this catchment net discharge and gross hydrologic gains were inversely related to the average flowpath gradients within the valley bottom and local hillslope contributing areas copyright 2013 john wiley sons ltd

evidence from western north america for rapid shifts in climate during the last glacial maximum the estancia basin in southwestern united states contains evidence for strong and rapid pulsations in the supply of moisture brought into the region during the last ice age the pulses were recorded during episodes of stream discharge that spread plumes of fresh water laden with quartz sand over the saline lake the largest pulses in stream discharge lasted only a few decades were organized into cycles that were spaced approximately 200 to 250 and 2000 years apart and were of sufficient magnitude to freshen and maintain the lake at its maximum recorded elevation

anisotropy and depth related heterogeneity of hydraulic conductivity in a bog peat ii modelling the effects on groundwater flow anisotropy and heterogeneity of hydraulic conductivity k are seldom considered in models of mire hydrology we investigated the effect of anisotropy and heterogeneity on groundwater flow in bog peat using a steady state groundwater model in five model simulations four sets of k data were used the first set comprised measured k values from an anisotropic and heterogeneous bog peat these data were aggregated to produce the following simplified data sets an isotropic and heterogeneous distribution of k an isotropic and homogeneous distribution and an anisotropic and homogeneous distribution we demonstrate that where anisotropy and heterogeneity exist groundwater flow in bog peat is complex fine scale variations in k have the potential to influence patterns and rates of groundwater flow however for our data at least it is heterogeneity and not anisotropy that has the greater influence on producing complex patterns of groundwater flow we also demonstrate that patterns and rates of groundwater flow are simplified and reduced when measured k values are aggregated to create a more uniform distribution of k for example when measured k values are aggregated to produce isotropy and homogeneity the rate of modelled seepage is reduced by 28 we also show that when measured k values are used the presence of a drainage ditch can increase seepage through a modelled cross section our work has implications for the accurate interpretation of hydraulic head data obtained from peat soils and also the understanding of the effect of drainage ditches on patterns and rates of groundwater flow

a continuous high resolution record of late pleistocene climate variability from the estancia basin new mexico lake sediments that accumulated in the estancia basin central new mexico provide a detailed record of submillennial latest pleistocene climatic oscillations sedimentologic biologic and geochemical proxies for changes in salinity and lake level were used to identify episodes of wet and dry climate that occurred between 24 and 12 k y b p as dated by 14c by means of accelerator mass spectrometry from shoreline and basin center deposits these dates determine the timing and duration of the episodes of wet and dry climate the lake expanded and contracted repeatedly during the last glacial maximum and fluctuated near its highest elevation several times during the interval ca 20 to 15 k y b p a pronounced lowstand lasting 1 k y occurred between ca 15 and 14 k y b p followed by two more highstands of the lake between ca 14 and 12 5 k y b p desiccation of the perennial lake after 12 k y b p was followed by a final poorly dated highstand at ca 10 k y b p the record of lake level fluctuations from the estancia basin provides a high resolution record of changes in water budget in a basin the comparatively simple physiography and hydrogeology of which ensured a direct response to the strong climatic fluctuations that occurred during the last glacial maximum and termination

hydrology of subarctic canadian shield soil filled valleys the canadian shield landscape includes bedrock uplands and valleys infilled with soil a site near yellowknife in subarctic canada was studied to elucidate the hydrological behaviour of soil filled valleys a suite of hydrological processes was found to be important in the studied valley including snowmelt and rainfall ground frost development evaporation infiltration lateral inflow from adjacent uplands and surface and subsurface flows valley storage requirements during snowmelt are met by local meltwater infiltration but lateral inflows in the summer are needed to satisfy the storage before runoff can be generated from the valley the valleys perform three functions of collecting vertical and lateral water inputs retaining and losing the water held in storage and transferring water down the valley and generating local outflow unlike channel flows in humid areas runoff from the upper valley has to meet the storage demands of the lower valley segments often causing seepage loss along flow paths to render the flows intermittent a fill and spill runoff system is proposed in which the valley physiography results in a series of segments with varying storage conditions as water is supplied to the valley each segment has to be filled until its storage threshold for runoff is exceeded then subsurface or surface flows will be generated but these flows may be arrested to furnish water to satisfy the storage requirements of the segments downstream such a flow system applies also to other valleys in the shield environment

sequence stratigraphy of lacustrine deposits a quaternary example from the bonneville basin utah the late quaternary lacustrine sedimentary record in the bonneville lake basin in the eastern great basin provides an excellent example of sequence stratigraphy two sequences referred to as the little valley and bonneville alloformations are exposed in the bluffs of the sevier river where it has entrenched its pleistocene delta between leamington and delta utah both alloformations contain offshore marl units and fine grained deltaic or underflow fan deposits they can be identified and mapped by tracing the unconformity separating them and employing a number of geochronometric tools including amino acid epimerization in fossil gastropods radiocarbon and thorium 230 ages and basaltic tephrochronology thin transgressive sand of the little valley alloformation is overlain by deeper water marl and down lapping regressive phase deltaic silt the bonneville alloformation lies unconformably above the little valley deposits fine grained deltaic sediments deposited during the transgressive phase of lake bonneville fill the entrenched sevier river valley that was eroded subsequent to the little valley lake cycle marl deposited during the deep water phase is overlain by down lapping deposits of the regressive phase below the provo shoreline but is the uppermost unit in the altitudinal range where the lake was lowered catastrophically during the bonneville flood the sequence stratigraphic interpretation leads to the conclusion that the sevier river delta as a whole is probably made up of a number of sediment sequences each composed of several facies recognition of this complexity could be important in potential applications of the stratigraphic model

a 180 000 year pollen record from owens lake ca terrestrial vegetation change on orbital scales abstract pollen from the upper 90 m of core ol 92 from owens lake is a climatically sensitive record of vegetation change that indicates shifts in the plant associations representing warm and cold desertscrub pinyon juniper woodland and pine fir forest during the past 180 000 years these changes are synchronized with glacial interglacial cycles during glacial and stadial climates juniper woodland expanded downslope and replaced warm desert shrubs while upper montane and subalpine forests in the arid inyo mountains also expanded and those in the sierra nevada were displaced by the ice cap and periglacial conditions conversely during interglacial and interstadial climates warm desert plants expanded their range in the lowlands juniper and sagebrush retreated upslope and montane and subalpine forests expanded in the sierra nevada the reconstructed vegetation history demonstrates a regional climatic response and the congruence of the pollen sequence with marine and ice cap oxygen isotope stratigraphies suggests a link between regional vegetation and global climate change at orbital scales

cave minerals of the world 2nd edition by carol hill and paolo forti national speleological society huntsville al 463 p isbn number 1 879961 07 5 70 00 think about all of those spectacular displays of mineral crystals that grace the world s mineral museums a great many of the large faceted crystals grew in some sort of cavity over long periods of time such mineral crystals are discovered in vugs pockets and cavities exposed in mines and quarries the conditions under which they were found are very different from the conditions under which they grew the fluids from which they grew are long gone a challenge for mineralogists to deduce from the surviving clues of trace elements isotopes and fluid inclusions now consider a cave it also is a cavity maintaining conditions of constant temperature water vapor pressure and carbon dioxide pressure for long periods of time this is also an environment where minerals can grow but in the case of many caves human observers can watch the growth process in progress some cave minerals appear as large faceted crystals some are nondescript crusts of little beauty but fascinating mineralogy most have formed from flowing dripping and seeping water and thus take on shapes dictated by the idiosyncrasies of the moving water such mineral deposits are known as speleothems stalactites stalagmites flowstone and a host of more intricate shapes hill and forti illustrate speleothems with some spectacular color photographs the authors have solicited contributions from cave photographers all over the world and without exception the

the hydrology and methylmercury dynamics of a precambrian shield headwater peatland a hydrobiogeochemical investigation of a small headwater peatland located in the experimental lakes area northwestern ontario canada examined the surface and subsurface hydrologic pathways and their relation to the movement and spatial variability of methylmercury ch3hg the hydrology of the peatland controls the mass flux of ch3hg to a downstream pond from the terrestrial ecosystems and influences the production and or accumulation of ch3hg in the peatland distinct zones of groundwater recharge and discharge were observed within the peatland and these corresponded to low and high ch3hg concentrations respectively in pore water the magnitude and flux of ch3hg from the peatland was governed by the area of the peatland and surrounding uplands contributing runoff there was a threefold increase in ch3hg concentration as stream base flow passed from the origin of the stream at the hillslope peatland margin to the stream outlet at the peatland lake interface this relative increase in concentration was maintained during storm flow conditions even though the discharge was up to 10 times greater indicating that the peatland is a large source of ch3hg methylmercury laden peat pore water found near the surface of the peatland in areas of groundwater discharge moves to the stream as the water table rises to the peat surface of a total of 12 6 mg ch3hg leaving the peatland during the 112 day study period less than 1 was transported directly by groundwater 41 was transported in stream base flow and the remaining 58 was transported by storm flow however storm flow conditions occurred only 16 of the time indicating the significance of episodic ch3hg flux from headwater catchments on the precambrian shield

orbital control of long term moisture in the southwestern usa 1 regional lake sediment records including late pleistocene lake estancia new mexico show that the southwestern usa was wetter than present over the last glacial maximum and drier during the holocene chronology of speleothems that mark groundwater levels in cavenee caverns near lake estancia indicates water level lowering through the cave during the early to middle holocene 8500 yr bp consistent with the timing of desiccation of lake estancia and deflation of the basin floor the speleothem record also shows the same wetter to drier climatic shift during the penultimate glacial and interglacial transition at 134 kyr bp subaqueous crusts formed when cave submerged to 121 kyr bp cave rafts formed during water table drop our data support wet glacials and dry interglacials as being a general feature of pleistocene climate in the southwestern usa the timing suggests that the process is orbitally controlled

climatic oscillations 10 000 155 000 yr b p at owens lake california reflected in glacial rock flour abundance and lake salinity in core ol 92 earlier wetter cycles the lake overflowed to fill a series chemical analyses of the acid soluble and clay size fractions of of downstream basins including china lake basin searles sediment samples 1500 yr resolution reveal oscillations of lake valley panamint valley and ultimately death valley salinity and of glacial advances in core ol 92 back to 155 000 yr smith and street perrott 1983 in 1992 the u s geological b p relatively saline conditions are indicated by the abundance survey drilled a 323 m deep core ol 92 into owens lake of carbonate and smectite both pedogenic and authigenic re sediments near the depocenter of the basin to obtain a continflected by ca sr and mg in the acid soluble suite and by cs2o uous record of silty clay sediment spanning the last 800 000 excess mgo and loi loss on ignition in the clay size fraction yr a multiparameter reconnaissance study of the entire core rock flour produced during glacial advances is represented by ca 7000 yr resolution reported in a 13 chapter summary the abundance of detrital plagioclase and biotite in the clay size volume smith and bischoff 1997 revealed cycles characfraction the ratio of which remains essentially constant over the terized by closed and overflowing lake conditions entire time span these phases are quantitatively represented by na2o tio2 ba and mn in the clay fraction the rock flour record we report here the results of a second part of an intermediindicates two major ice advances during the penultimate glacial ate resolution study aimed at resolving shorter term events cycle corresponding to marine isotope stage mis 6 no major over just the past 155 000 yr using sediment samples of ca advances during the last interglaciation entire mis 5 and three 1500 yr resolution taken over the uppermost 90 m of olmajor advances during the last glacial cycle mis 2 3 and 4 92 the companion study menking et al 1997 reports on the ages of the latter three correspond rather well to 36 cl dates grain size tic total inorganic carbon content and stable reported for sierra nevada moraines the onset of the last intergla isotopic measurements proxies which tend to reflect variaciation is shown by abrupt increases in authigenic caco3 and an tions in water flow and which are most representative of abrupt decrease in rock flour at about 118 000 yr b p according variations during closed lake conditions the present study to our time scale in contrast the boundary appears to be gradual was concerned primarily with seeking a proxy for glacial in the d 18 o record in which the change from light to heavy values advances we found that the mineralogy and chemistry of begins at about 140 000 yrs b p the exact position of the termination therefore may be proxy dependent conditions of high car the clay fraction provide indices of glacial rock flour we bonate and low rock flour prevailed during the entire period from also report on the composition of the acid soluble carbonate 118 000 yr b p until the glacial advance at 53 000 yr b p signaled fraction which gives further detail on closed lake conditions

scaling and physiographic controls on streamflow behaviour on the precambrian shield south central ontario summary relationships explaining streamflow behaviour in terms of drainage basin physiography greatly assist efforts to extrapolate streamflow metrics from gauged to ungauged basins in the same landscape the dorset environmental science centre desc has monitored streamflow from 22 small basins 3 4 190 5 ha on the precambrian shield in south central ontario in some cases since 1976 the basins exhibit regional coherence in their interannual response to precipitation however there is often a poor correlation between streamflow metrics from basins separated by as little as 1 km this study assesses whether inter basin variations in such metrics can be explained in terms of basin scale and physiography several characteristics annual maximum minimum and average flow exhibited simple scaling with basin area while magnitude range and timing of annual maximum daily runoff showed scaling behaviour consistent with the representative elementary area rea concept this rea behaviour is partly attributed to convergence of fractional coverage of the two dominant and hydrologically contrasting land cover types in the desc region with increasing basin size three principal components pcs explained 82 4 of the variation among basin physiographic properties and several runoff metrics magnitude and timing of annual minimum daily runoff mean number of days per year with 0 streamflow exhibited significant relationships with one or more pc significant relationships were obtained between basin quickflow qf production and the pcs on a seasonal and annual basis almost all of which were superior to simple area based relationships basin physiography influenced qf generation via its control on slope runoff water storage and hydrologic connectivity however this role was minimized during spring when qf production in response to large rain on snow events was relatively uniform across the desc basins the pc based relationships and inter seasonal changes in their form were consistent with previous research conducted at point slope and basin scales in the desc region and perceptions of key hydrological processes in these small basins may not have been as readily obtained from scaling studies using streamflow from larger basins this process understanding provides insights into scaling behaviour beyond those derived from simple scaling and rea analyses the physiography of the study area is representative of large portions of the precambrian shield such that basin streamflow behaviour could potentially be extended across much of south central ontario this would assist predictions of streamflow conditions at ungauged locations development and testing of hydrological models for this landscape and interpretation of inter basin and intra annual differences in hydrochemical behaviour on the southern precambrian shield

timing of the last glacial maximum from observed sea level minima during the last glacial maximum ice sheets covered large areas in northern latitudes and global temperatures were significantly lower than today but few direct estimates exist of the volume of the ice sheets or the timing and rates of change during their advance and retreat here we analyze four distinct sediment facies in the shallow tectonically stable bonaparte gulf australia each of which is characteristic of a distinct range in sea level to estimate the maximum volume of land based ice during the last glaciation and the timing of the initial melting phase we use faunal assemblages and preservation status of the sediments to distinguish open marine shallow marine marginal marine and brackish conditions and estimate the timing and the mass of the ice sheets using radiocarbon dating and glacio hydroisostatic modelling our results indicate that from at least 22 000 to 19 000 calendar years before present land based ice volume was at its maximum exceeding today s grounded ice sheets by 52 5 x 10 exp 6 cu km a rapid decrease in ice volume by about 10 percent within a few hundred years terminated the last glacial maximum at 19 000 250 years

climatic hydrologic oscillations since 155 000 yr b p at owens lake california reflected in abundance and stable isotope composition of sediment carbonate abstract sediment grain size carbonate content and stable isotopes in 70 cm long 1500 yr channel samples from owens lake core ol 92 record many oscillations representing climate change in the eastern sierra nevada region since 155 000 yr b p to first order the records match well the marine 18o record at owens lake however the last interglaciation appears to span the entire period from 120 000 to 50 000 yr b p according to our chronology and was punctuated by numerous short periods of wetter conditions during an otherwise dry climate sediment proxies reveal that the apparent timing of glacial interglacial transitions notably the penultimate one is proxy dependent in the grain size and carbonate content records this transition is abrupt and occurs at 120 000 yr b p in contrast in the isotopic records the transition is gradual and occurs between 145 000 and 120 000 yr b p differences in timing of the transition are attributed to variable responses by proxies to climate change

hydrology of a headwater basin wetland groundwater discharge and wetland maintenance the link between groundwater and surface hydrology in a small headwater drainage basin in the zone of glacial deposition of southern ontario south of the precambrian shield was examined for two years the basin is situated in a discharge zone of a regional aquifer and contains a small treed spring fed swamp the swamp exists because of the groundwater and has little effect on the maintenance of streamflow groundwater input to the swamp is an order of magnitude larger than precipitation groundwater of local and regional origin passes through the swamp by two routes surface streamlets where groundwater that emerges at specific seepage points in the swamp is conveyed over the ground surface with little interaction with the swamp itself and by diffuse seepage in the swamp and through the bed of the stream while the diffuse seepage input is the smaller component of groundwater it maintains the swamp s saturation groundwater input to the swamp from the specific seepage points and diffuse flow varies little over a year therefore the saturation of the swamp and baseflow from the basin display little seasonal variation compared to other wetland types the existence of the valley bottom in the headwater basin alters the seasonal and storm hydrology and is important to biogeochemical transformation of emerging groundwater

constraining groundwater discharge in a large watershed integrated isotopic hydraulic and thermal data from the canadian shield or a thin veneer of coarse grained sediments natural conservative d 2 h d 18 o cl and specific conductance radioactive 222 rn and thermal tracers are integrated with streamflow measurements and a steady state advective model to delimit the discharge locations and quantify the discharge fluxes to lakes wetlands creeks and the tay river the groundwater discharge rates to most surface water body types are low indicating that the groundwater and surface water system may be largely decoupled in this watershed compared to watersheds underlain by porous media groundwater discharge is distributed across the watershed rather than localized around lineaments or high density zones of exposed brittle fractures the results improve our understanding of the rate localization and conceptualization of discharge in a large fractured rock watershed applying hydraulic isotopic or chemical hydrograph separation techniques would be difficult because the groundwater discharge signal is small compared to the background surface water inflows or volumes of the surface water bodies although this study focuses on a large watershed underlain by fractured bedrock the methodology developed is transferable to any large regulated or unregulated watershed the low groundwater discharge rates have significant implications for the ecology sustainability and management of large crystalline watersheds

aquifer peatland connectivity in southern quebec canada in areas where peatlands are abundant they are likely to play a significant role in the hydrological and hydrogeological dynamics of a watershed although individual case studies are reported in the literature there is a large range of aquifer peatland interactions and there is a need to understand the controls of these interactions the objectives of this study were 1 to better understand aquifer peatland connections and how these may be predicted by geology and geomorphic location and 2 to provide a variety of reference sites for glacial geological settings slope and depression peatlands were studied in the abitibi temiscamingue region and in the st lawrence lowlands two contrasting regions of southern quebec a total of 12 transects that span a shallow aquifer peatland interface were instrumented with piezometers field investigations included peatland characterization monthly water level monitoring and continuous hydraulic head measurements with pressure transducers the results indicate that 7 of the 12 transects receive groundwater from the surrounding shallow aquifer at the peatland margin four lateral flow patterns were identified and associated with slope peatlands parallel inflow and divergent flow and with depression peatlands convergent flow and parallel outflow vertical hydraulic gradients suggest that water flows mainly downwards i e from the peatland to the underlying mineral deposits vertical connectivity appears to decrease as the distance from the peatland margin increases all of these exchanges are important components in the sustainability of peatland hydrogeological functions the regional comparison of aquifer peatland flow dynamics performed in this study provides a new set of referenced data for the assessment of aquifer peatland connectivity

the transport of u and th series nuclides in sandy confined aquifers a comprehensive evaluation of the transport of u th ra and rn nuclides of the 238 u and 232 th decay series in an unconfined sandy aquifer long island ny was conducted groundwater data are compared with results of a theoretical transport model of weathering of aquifer grains and interaction with surface coatings to establish relationships between the concentrations of the radionuclide activities in the water and flow line distance the data provide estimates for geochemical parameters including weathering rates and chemical reactivities in both the vadose zone and the aquifer a theoretical treatment of the transport is presented that considers the reaction between the water and a reactive surface layer it is found that a model with chemical exchange between the surface layer and the water for all species is not valid and that the effects of saturation and irreversible precipitation of th is required the water table shows a relatively wide range in u activities the only element in the u th series for which vadose zone input is significant in the aquifer high weathering of u and recoil inputs of 234 u to the water occur in the upper 3 m of the vadose zone while lower weathering and removal of u from the water occur below the deeper aquifer has variable 238 u activities that can be accounted for by input from the vadose zone and is not a result of non conservative behavior the isotopic composition of u is shown to be directly related to the recoil rate relative to the weathering rate the wide range of 238 u in the aquifer waters is a reflection of diverse vadose zone inputs showing that dispersive mixing is not a dominant effect the higher values of 234 u in the aquifer reflect the recoil weathering input ratios from within the aquifer where the weathering rate is lower than the vadose zone both high u activities and high 234 u values cannot be obtained in the vadose zone or within reasonable flow distances in the aquifer radium isotopes are found to be in exchange equilibrium with the surface layer 224 ra 228 ra and 226 ra have comparable activities throughout the aquifer in the vadose zone the dominant input of ra to groundwater is weathering and recoil as found elsewhere the 222 rn in the water is a large fraction 5 of the rn produced in the aquifer rock this cannot be due to ra precipitation onto surface coatings in the aquifer as supported by present weathering with th in exchange equilibrium with the surface layer it is found that th is saturated in the waters under oxidizing conditions so that the weathering input is irreversibly precipitating onto surfaces however it is shown that under somewhat reducing conditions th activities are much higher and the th u ratio in the solution is approximately that of the rock we propose that under oxidizing conditions the source of rn is a surface coating enriched in 232 th and 230 th this th was precipitated in an earlier phase during rapid dissolution of readily weathered phases that contain 10 of the u th inventory of the rock with the associated u carried away in solution therefore the previously precipitated 230 th and 232 th produce daughter nuclides in the surface coating which are the dominant contributors of ra and rn to the ground water in particular rn is provided by very efficient losses by diffusion or recoil from the surface coating this then does not require recent large recoil losses from the parent rock or the presence of nanopores in the rock the first data of both long lived 232 th and short lived 234 th and 228 th in ground water is reported the th isotope activities indicate that desorption kinetics are slow and provide the first estimate based on field data of the th desorption rate from an aquifer surface the mean residence time of th in the surface coating is 3000 y while in the water it is 1 h ra is in partition equilibrium with the aquifer surface layer however the strong fixation of th on surface coatings is very susceptible to changes in oxidation state as is shown by a comparison of two adjacent aquifers this makes it difficult to define with certainty the retentive characteristics in natural systems in general it is shown that the distributions of naturally occurring nuclides can be used to calculate values for transport parameters that are applicable to the transport of anthropogenic nuclides

are all runoff processes the same copyright 2013 john wiley sons ltd introduction research on runoff processes to date has focused on the differences between the main divisions of runoff partitioning indeed our major advancements in runoff theory have come with new differentiations of different forms of overland flow and subsurface stormflow these studies of how runoff processes are different have resulted in our current summaries of runoff regimes conceptually e g the variable source area vsa concept and codified in our models e g topmodel and its derivatives such summaries are captured in iconic figures in textbooks that we teach new generations of hydrologists the most popular of which is shown in figure 1 from dunne 1983 and reproduced more recently in wagener et al 2007 and mirus and loague 2013 although such process differentiation was useful as new dominant forms of runoff were discovered in different climates with different soils slope morphologies and vegetation cover continued differentiation does not appear helpful for improved understanding of runoff dynamics and streamflow generation we seem to have exhausted the main list of runoff classes infiltration excess overland flow saturation excess overland flow and subsurface stormflow some decades ago with perhaps the last wave of minor updates to these processes coming in the 1980s and early 1990s in response to isotope tracing demonstration of the importance of stored water and clarification of differences between hydrologic and hydraulic time scales see reviews by bonell 1993 1998 and in bachmair and weiler 2011 in the spirit of sivapalan 2009 i wonder if it is more useful now to change our organizing question from how are runoff processes different to how are runoff processes similar in many ways i am simply building upon and restating what others have said in recent useful statements on the importance of boundary conditions and flux closures beven 2006 the need for new theory e g troch et al 2008 and new ways of considering runoff systems spence 2010 asking if all runoff processes are the same conceptually is a possible new way to come at runoff process research to aid improved process measurement understanding and prediction through new flexible model structural approaches similar to fenicia et al 2011 across diverse regions it opens up new research questions such as what can we learn about subsurface stormflow from overland flow and vice versa can we recognize things on the surface where boundary conditions are visible that may help guide new theory for the subsurface where such boundary controls are hidden here i present a simple analogical reasoning that shows how all runoff processes are similar this comes following the viewing of many dozens of hillslopes and catchment sites across the world for 25 years especially although i do note that pioneering work in the 1990s in deglaciated landscapes particularly in canada has shown new behaviours outside of these three classes largely linked to groundwater and wetland processes see branfireun and roulet 1998 peters et al 1995 and others