determining vertical leakage from the great artesian basin australia through up scaling field estimates of phreatic evapotranspiration summary understanding the water balance of large groundwater systems is fundamental for the sustainable management of the resource the vertical leakage i e discharge to upper aquifers or the unconfined water table component of the great artesian basin gab is an example of a poorly constrained but large component of the water balance of australia s largest groundwater resource field estimates of phreatic evapotranspiration et were made at discharge zones along the southwestern margin of the gab using eddy covariance station and micro lysimeter measurements and inversion of chloride isotope soil profile measurements the field estimates were assigned to three major landforms associated with areas of increasingly higher evaporative discharge and progressively decreasing depths to the water table these landforms were mapped using remote sensing and digital elevation data with characteristically higher soil moisture salt precipitation and lower surface temperature compared to areas distal to discharge zones based on the field measurements broad ranges of phreatic et 0 5 10 10 100 and 100 300 mm y 1 were assigned to the major land types the higher phreatic et discharge zones mapped by supervised classification of satellite data are 8 28 of the total regional vertical leakage component estimated by numerical modelling of the gab in comparison the higher discharge zones estimated by landform mapping are 73 251 of the total vertical leakage component estimated by modelling the mapped distribution of the high discharge areas has important implications for modelling of the gab in the western sub basin most of the estimated recharge can be accounted for by phreatic et in the high discharge zones located around the basin margins implying that vertical leakage rates distal to the margins are very low and that discharge may exceed current recharge in contrast the results for the eastern sub basin suggest that vertical leakage rates around the south australian portion of the basin margin are low and that more of the vertical leakage component in the eastern sub basin is occurring distal to the basin margins consequently the pathways for vertical leakage in the eastern sub basin are likely to be more complex than for the western sub basin

linking water quality changes to geochemical processes occurring in a reactive soil column during treated wastewater infiltration using a large scale pilot experiment insights into mn behavior the spatial and temporal evolution of the physical properties and chemical composition of water and soil during the infiltration of treated wastewater through a reactive soil column at the pilot scale 25 m3 were investigated for 18 months major and trace elements and organic carbon were measured monthly in treated wastewater output water and pore water o2 co2 ch4 n2o n2 h2s and h2 were measured occasionally in soil air geochemical processes occurring in the soil changed rapidly over the study period nitrification was effective in the top 1 5 m of soil during the first 8 months thereafter the organic carbon load from treated wastewater and the treated wastewater left above the infiltration surface due to clogging organic matter accumulation and precipitation of carbonates created anaerobic conditions that led to denitrification and reductive dissolution of mn oxides in the soil the latter led to the release of both mn exceeding the who drinking water limit by a factor of up to 2 and ni that was strongly associated with the mn oxides forty five percent of the ni that had accumulated in the soil during the first year was released dissolved element concentrations were non uniform because of the spatial and temporal distribution of redox reactions in the soil due to the heterogeneous distribution of organic matter and or non uniform flow water saturation residence time the soil was very effective in removing phosphate fe and li and removing degrading organic carbon and nh4 in contrast ba no3 and to a lesser extent ca were exported removal rates were moderate for as and total nitrogen and low for k na ni and mn however removal rates of nitrogen species nh4 no3 total nitrogen mn fe ni and as were strongly dependent on redox conditions which varied during the experiment the evolution of geochemical processes occurring in the soil column therefore has significant implications on the quality of water moving from the soil to groundwater and provides key knowledge for the management of groundwater under artificial recharge

catchment scale surface water groundwater connectivity on china s loess plateau abstract thick loess deposits up to 200 m deep and a large unsaturated zone up to 100 m below the soil surface complicate the interactions between surface water and groundwater in china s loess plateau especially in catchments characterized by tableland gully topography in this region in the heihe watershed electrical conductivity ec chloride cl concentrations and stable water isotope data d and 18 o obtained during dry and wet seasons in the period of 2012 2014 are used to determine the relationship between surface water and groundwater ec and cl concentrations are found to be unsuitable for analyzing the relationship between surface water and groundwater in this watershed due to the impacts of chemical weathering the stable water isotope data indicate a gaining surface water system i e groundwater and gully runoff both recharge streamflow further groundwater appears to dominate the hydrologic cycle in the watershed therefore water resources management on china s loess plateau should pay more attentions to groundwater protection

monitoring groundwater storage changes in complex basement aquifers an evaluation of the grace satellites over east africa although the use of the gravity recovery and climate experiment grace satellites to monitor groundwater storage changes has become commonplace our evaluation suggests that careful processing of the grace data is necessary to extract a representative signal especially in regions with significant surface water storage i e lakes reservoirs in our study we use cautiously processed datasets including grace lake altimetry and model soil moisture to reduce scaling factor bias and compare grace derived groundwater storage changes to in situ groundwater observations over parts of east africa over the period 2007 2010 a strong correlation between in situ groundwater storage change and grace groundwater estimates spearman s 0 6 is found piecewise trend analyses for the grace groundwater estimates reveal significant negative storage changes that are attributed to groundwater use and climate variability further analysis comparing groundwater and satellite precipitation datasets permits identification of regional groundwater characterization for example our results identify potentially permeable and or shallow groundwater systems underlying tanzania and deep and or less permeable groundwater systems underlying the upper nile basin regional groundwater behaviors in the semi arid regions of northern kenya are attributed to hydraulic connections to recharge zones outside the sub basin boundary our results prove the utility of applying grace in monitoring groundwater resources in hydrologically complex regions that are under sampled and where policies limit data accessibility this article is protected by copyright all rights reserved

the application of sequence stratigraphy to upper carboniferous fluvio deltaic strata of the onshore uk and ireland implications for the southern north sea stratigraphical correlations and fades interpretations of upper carboniferous fluvio deltaic strata have been based traditionally on cyclothems bound by marine flooding surfaces marine bands the recent recognition of major regionally extensive erosional unconformities exxon style sequence boundaries within selected cyclothems questions their validity as units of genetically related strata u sing examples from the carboniferous of the onshore uk and ireland we present sedimentological criteria for the recognition of sequence boundaries placing particular emphasis on the regional context of these surfaces sequence boundaries comprise widespread deeply eroded surfaces at the base of major fluvial sandstone complexes and laterally equivalent palaeosols developed on interfluves at the margins of the fluvial complexes these sequence boundaries define units of genetically related strata sequences which contain other key surfaces of time stratigraphic significance including marine bands and regionally extensive coals the recognition of key surfaces enables the construction of a high resolution stratigraphic framework within which coeval facies relationships can be interpreted sequence boundaries can be correlated between individual basins in the onshore uk by reference to their position in relation to a particular marine band for example the sequence boundary at the base of the farewell rock in the south wales basin can be correlated with that at the base of the rough rock in the pennine basin northern england since both these sandstone bodies are directly overlain by the subcrenatum marine band interbasinal correlations of this nature imply that potential fluvial sandstone reservoirs within major incised valley fills in the upper carboniferous strata of the southern north sea can be predicted by correlation with the onshore uk the stratigraphical framework can be extended and tested using core and well log data particularly spectral gamma ray data which are able to identify key sequence stratigraphic surfaces

discussion on large sea small tides the late carboniferous seaway of nw europe roger higgs writes wells et al 2005 a b produced an innovative and thought provoking numerical model of tides in the late carboniferous seaway of nw europe predicting very low tidal ranges 1 m consistent with the scarcity of sedimentary evidence for weak tides reported in the corresponding rocks based on the model wells et al 2005 a argued intuitively that tidal range was minimum during glacioeustatic highstands and maximum during lowstands and transgressions i would argue the converse during highstands not only was the water volume mass greater leading potentially to larger tides but also any tide in the adjacent ocean would necessarily be passed into the seaway adding to the locally generated tide this is a weakness of the model the oceanic tidal influence was not incorporated for simplicity wells et al 2005 a p 418 in contrast during lowstands the seaway became a freshwater lake or chain of lakes perched at the level of the outflow sill and bordered by incised highstand prograded deltas and alluvial plains lake bude of higgs 1991 2004 disconnected from the global ocean the lake would have had an extremely low tidal range 5 cm as in all lakes because of the relatively small water volume talbot allen 1996 indeed no evidence for tides has been reported in lake bude deposits ross crackington and bude formations of ireland and england higgs 1991 2004 and references therein however given the scarce evidence reported elsewhere in the seaway sedimentary structures indicative of weak tidal currents e g ripples with foreset slack water mud drapes rhythmic lamination opposed ripples may eventually be discovered in the lake bude formations probably associated with the volumetrically minor shale bands with brackish and marine fossils higgs 1991 2004 representing transgressions and highstands when

groundwater recharge and evolution in the dunhuang basin northwestern china groundwater recharge and evolution in the quaternary aquifer beneath the dunhuang basin was investigated using chemical indicators stable isotopes and radiocarbon data to provide guidance for regional water management the quality of groundwater and surface water is generally good with low salinity and it is unpolluted the dissolution of halite and sylvite from fine grained sediments controls concentrations of na and k in the groundwater but na cl molar ratios 1 in all samples are also indicative of weathering of feldspar contributing to excess na the dissolution of carbonate minerals yields ca2 to the groundwater thereby exerting a strong influence on groundwater salinity the delta o 18 and delta h 2 values in unconfined groundwater are enriched along the groundwater flow path from sw to ne in contrast confined groundwater was depleted in heavy isotopes with mean values of 10 4 parts per thousand delta o 18 and 74 4 parts per thousand delta h 2 compared with the precipitation values all of the groundwater samples were strongly depleted in heavy isotopes indicating that modern direct recharge to the groundwater aquifers in the plains area is quite limited the unconfined water is generally young with radiocarbon values of 64 9 79 6 pmc in the northern basin radiocarbon content in the confined groundwater is less than 15 pmc and an uncorrected age of similar to 15 ka indicates that this groundwater was recharged during a humid climatic phases of the late pleistocence or early holocene the results have important implications for inter basin water allocation programmes and groundwater management in the dunhuang basin c 2012 elsevier ltd all rights reserved

use of flow modeling to assess sustainability of groundwater resources in the north china plain 1 the north china plain ncp is one of the global hotspots of groundwater depletion currently our understanding is limited on spatiotemporal variability in depletion and approaches toward more sustainable groundwater development in this region this study was intended to simulate spatiotemporal variability in groundwater depletion across the entire ncp and explore approaches to reduce future depletion simulated predevelopment groundwater recharge 13 km3 yr primarily discharged as base flow to rivers and evapotranspiration initial groundwater storage was estimated to be 1500 km3 of drainable storage in shallow aquifers and 40 km3 of compressive storage in deep aquifers simulated groundwater depletion from 1960s to 2008 averaged 4 km3 yr cumulative depletion was 50 km3 20 of pumpage in the piedmont district 103 km3 20 in the central plain and 5 km3 12 in the coastal plain however depletion varied with time 2 5 km3 yr in the 1970s 4 0 in the 1980s 2 0 in 1990 1996 7 0 in 1997 2001 and 4 0 in 2002 2008 recharge also varied spatially averaging 120 mm yr and concentrated in the piedmont district 200 350 mm yr while lower in the central and coastal plains 50 100 mm yr simulation of several alternatives including managed aquifer recharge increased water use efficiency brackish water use and interbasin water transfer indicated that the combination of these strategies could be used to recover groundwater storage by 50 km3 over a 15 year period this study provides valuable insights for developing more sustainable groundwater management options for the ncp the methods are useful for managing other depleted aquifers

channel formation and migration by mass flow processes in the lower carboniferous fluviatile fell sandstone group northeast england small steep sided narrow channels locally developed within the braided fluviatile lower carboniferous fell sandstone of northeast england are attributed to mass flow processes initiated by channel bank slumping the channels have sharp undisturbed margins and are filled with moderately well sorted medium to coarse sandstone identical to the sandstone which they cut most channel fills are structureless but a few show diffuse concentric marginal laminations laminations also occur towards the top of channel fills but they are less regular and show low amplitude trough like undulations channel margin inclinations range from 13 to 55 and channel depths vary between 1 7 m and 2 5 m the channels which are only seen in profile are orientated perpendicular to the local and regional palaeocurrent trend and cut through structureless sandstone and planar cross stratified sandstone characterized by compound and compound complex bar bedforms only one channel has both margins preserved and of the remainder seven only one has its northern margin preserved undercutting and retrogressive slumping of the sandy channel bank is thought to have initiated a subaqueous sediment gravity flow which moved across the main channel along a transverse scour at the base of the slip face of a large composite bar bedform such scours have strong asymmetric profiles with the steeper slope along the base of the active slip face northern side and the lower slope on the downstream southern side of the scour thus the northern channel margin was steeper less stable and more prone to collapse than the southern margin and is almost never preserved flow reconstruction indicates that on entering the channel a hydraulic jump developed at the change in slope and the flow became more turbulent and erosive scoured sand incorporated into the flow increased concentration and shearing along the boundaries reverse shear was also exerted by the overlying current on top of the flow but the central part remained relatively unaffected the presence or absence of marginal laminations is probably related to marginal shearing and flow dilution deposition occurred in response to deceleration and frictional freezing of the sand flow

groundwater storage changes in the tibetan plateau and adjacent areas revealed from grace satellite gravity data abstract understanding groundwater storage gws changes is vital to the utilization and control of water resources in the tibetan plateau however well level observations are rare in this big area and reliable hydrology models including gws are not available we use hydro geodesy to quantitate gws changes in the tibetan plateau and surroundings from 2003 to 2009 using a combined analysis of satellite gravity and satellite altimetry data hydrology models as well as a model of glacial isostatic adjustment gia release 5 grace gravity data are jointly used in a mascon fitting method to estimate the terrestrial water storage tws changes during the period from which the hydrology contributions and the gia effects are effectively deducted to give the estimates of gws changes for 12 selected regions of interest the hydrology contributions are carefully calculated from glaciers and lakes by icesat 1 satellite altimetry data permafrost degradation by an active layer depth ald model soil moisture and snow water equivalent by multiple hydrology models and the gia effects are calculated with the new ice 6g c vm5a model taking into account the measurement errors and the variability of the models the uncertainties are rigorously estimated for the tws changes the hydrology contributions including gws changes and the gia effect for the first time we show explicitly separated gws changes in the tibetan plateau and adjacent areas except for those to the south of the himalayas we find increasing trend rates for eight basins 2 46 2 24 gt yr for the jinsha river basin 1 77 2 09 gt yr for the nujiang lancangjiang rivers source region 1 86 1 69 gt yr for the yangtze river source region 1 14 1 39 gt yr for the yellow river source region 1 52 0 95 gt yr for the qaidam basin 1 66 1 52 gt yr for the central qiangtang nature reserve 5 37 2 17 gt yr for the upper indus basin and 2 77 0 99 gt yr for the aksu river basin all these increasing trends are most likely caused by increased runoff recharges from melt water and or precipitation in the surroundings we also find that the administrative actions such as the chinese ecological protection and construction project help to store more groundwater in the three rivers source region and suggest that seepages from the endorheic basin to the west of it are a possible source for gws increase in this region in addition our estimates for gws changes basically confirm previous results along afghanistan pakistan north india and bangladesh and clearly reflect the excessive use of groundwater our results will benefit the water resource management in the study area and are of particular significance for the ecological restoration in the tibetan plateau

stable isotope and noble gas constraints on the source and residence time of spring water from the table mountain group aquifer paarl south africa and implications for large scale abstraction abstract large scale groundwater abstraction is increasingly being used to support large urban centres especially in areas of low rainfall but presents particular challenges in the management and sustainability of the groundwater system the table mountain group tmg aquifer is one of the largest and most important aquifer systems in south africa and is currently being considered as an alternative source of potable water for the city of cape town a metropolis of over four million people the tmg aquifer is a fractured rock aquifer hosted primarily in super mature sandstones quartzites and quartz arenites the groundwater naturally emanates from numerous springs throughout the cape region one set of springs were examined to assess the source and residence time of the spring water oxygen and hydrogen isotopes indicate that the spring water has not been subject to evaporation and in combination with na cl ratios implies that recharge to the spring systems is via coastal precipitation although rainfall in the cape is usually modelled on orographic rainfall 18 o and 2 h values of some rainfall samples are strongly positive indicating a stratiform component as well comparing the spring water 18 o and 2 h values with that of local rainfall indicates that the springs are likely derived from continuous bulk recharge over the immediate hinterland to the springs and not through large and or heavy downpours noble gas concentrations combined with tritium and radiocarbon activities indicate that the residence time of the tmg groundwater in this area is decadal in age with a probable maximum upper limit of 40 years this residence time is probably a reflection of the slow flow rate through the fractured rock aquifer and hence indicates that the interconnectedness of the fractures is the most important factor controlling groundwater flow the short residence time of the groundwater suggest that recharge to the springs and the table mountain group aquifer as a whole is vulnerable to climate change and reductions in regional precipitation any plans for large scale abstraction to supplement the city of cape town water supply would need to factor this into models of maximum sustainable yield

multivariate indications between environment and ground water recharge in a sedimentary drainage basin in northwestern china abstract a paucity of studies on the interaction between environment and ground water recharge severely restricts the ability of people to assess future water resources under changing environment in this study an effort to explore the relationship between the arid environment and ground water recharge was carried out using multivariate statistical techniques in a sedimentary drainage basin the jungar in northwestern china hierarchical cluster analysis hca and principal components analysis pca were performed based on hydrogeochemical data to assess the ground water recharge and its governing factors observation of the hca and pca analytical results revealed a division of seven clusters c1 to c7 and three principal components pc1 to pc3 which explained 59 6 16 6 and 10 9 of the variance respectively and thus accounted for the majority of the total variance in the original dataset based on these q mode hca clusters and r mode pac scores dominant environmental processes influencing recharge regimes were identified i e geogenic geomorphoclimatic and anthropogenic which separated the recharge regimes into four zones zone i to zone iv zones i and ii c4 c1 were associated to elevated hydroclimate degree coupled to low salinity zone iii c2 c3 was associated to moderately elevated salinity and evidently elevated contamination but coupled to low hydroclimate degree zone iv c5 c6 c7 was associated mainly to elevated salinity coupled to low or inverse hydroclimate degree it revealed that the geogenic processes are more significant 60 than the geomorphoclimatic 17 and anthropogenic 11 processes as a result the overall recharge process is rather heterogeneous and is strongly environment dominated in the jungar drainage system compared with other watersheds in arid environment a distinctive feature of the jungar waters is that they are affected by a combination of natural and non natural events rather than following a steady and continuous geological evolution these will continue to influence the recharge regime of the jungar for a long time due to its steady tectonics and arid climate however changing rainfall but not snow is becoming the key factor driving changes in ground water resources in this drainage system as results of the decades of warming and humidification in northwestern china

sequence stratigraphy in active extensional basins implications for the interpretation of ancient basin fills abstract systematic variations in sequences their component units and their stacking patterns exist within rift basins these variations can be related to displacement gradients associated with the large scale 12 50 km segmentation of normal fault zones which control accommodation sediment supply and basin physiography sediment supply is also strongly influenced by the nature of pre rift drainage networks and variations in bedrock lithology high rates of hangingwall subsidence close to the centre of normal fault segments may cancel out the effects of glacio eustatic sea level fall so that accommodation development is normally characterized by the continual addition of new space the resulting sequences lack type 1 sequence boundaries and lowstand systems tracts and stack into aggradational sequence sets the adjacent footwall is subject to uplift which may lead to subaerial exposure and incision generating a composite type 1 sequence boundary away from the fault zone and near segment boundaries slip rates are much lower and hence relative sea level change is dominated by eustasy here falls in relative sea level are important resulting in type 1 sequences sequence stacking patterns reflect not only eustasy and local fault controlled subsidence but also the interaction of these with adjacent uplifting footwalls and or regional uplift tectonic influence on sequence development will be more pronounced during greenhouse times than icehouse times

high resolution sequence stratigraphy of the late namurian in the widmerpool gulf east midlands uk abstract analysis of facies stacking patterns and stratal surfaces within late namurian deltas of the widmerpool gulf has revealed 10 high frequency fourth order depositional sequences sequence correlation is based on the characteristic marine band fauna of their condensed sections in many instances sequence boundaries are difficult to recognize unless there is clearly demonstrable lowstand incision consequently it is often difficult to separate late highstand from falling stage progradation with any degree of confidence sequence thickness variations and the dominance of particular stratal surfaces and systems tracts were controlled by a longer period third order cycle of relative sea level rise and fall during the marsdenian yeadonian major fluvio deltaic sand bodies in the widmerpool gulf were formed by distributary channel progradation e g chatsworth grit during the late highstand and or falling stage systems tracts and by the filling of incised valleys e g ashover grit and rough rock following marked sea level falls channel belt and valley fill orientation was initially influenced by differential compaction but this influence decreased during the late namurian the recognition of incised valley fills within the late namurian has implications for estimating the magnitudes and periodicities of carboniferous relative sea level change

diagenesis of namurian fluvio deltaic sandstones from the trumfleet field south yorkshire abstract the namurian sequence of the trumfleet field south yorkshire uk contains four sandstone units between the gastrioceras subcrenatum and reticuloceras gracile marine bands each deposited in a period between glacio eustatic marine transgressions these medium to coarse grained sandstone units up to 25 m thick were deposited as multi channel upwards fining distributary channel fills within a predominantly argillaceous deltaic interdistributary and swamp complex associated sandstones are crevasse splay and overbank deposits four stages of diagenetic alteration can be identified early diagenesis eogenesis was controlled by the oxidation of organic matter causing reducing conditions to be established pyrite siderite and calcite are characteristic of this phase burial diagenesis mesogenesis can be divided into three stages the first early burial was characterized by dolomite and quartz cements the second intermediate burial was controlled by the generation of acidic pore fluids by the thermal maturation of organic matter in adjacent and down dip shales and was manifested by dissolution of feldspar and carbonate with the precipitation of kaolinite in secondary pores the third stage late burial was characterized by the precipitation of ankerite albite and illite cements integrating the diagenetic data with the burial history and modelling the source rock geochemistry of the wells allows the timing of diagenetic events to be predicted within absolute ranges early diagenesis took place very near the surface and early burial diagenesis occurred during the carboniferous from depths of only a few centimetres below the sediment water interface to up to 1500 m burial depth at approximately 140 my intermediate burial diagenesis took place when the rocks passed through the 80 c isotherm at approximately 140 my late burial diagenesis took place during maximum burial prior to tertiary uplift when temperatures in excess of 100 c were reached the present day porosity is secondary after carbonate and feldspar dissolution primary textural factors have little effect on the present reservoir properties which are controlled by diagenesis

geologic influence on groundwater salinity drives large seawater circulation through the continental shelf observations of offshore freshened groundwater and saline groundwater discharge along continental shelves have important implications for water resources ecosystem function and the composition of the ocean but they cannot be explained by basic theory we show that these independent observations are linked and result from processes that drive variable density groundwater flow through the spatial heterogeneity that is ubiquitous in geologic formations we use lithologic data to develop geostatistical models that mimic the architecture of coastal aquifers simulation of groundwater flow and salt transport through these random realizations shows that heterogeneity produces spatially complex subsurface salinity distributions that extend tens of kilometers offshore even at steady state the associated density gradients drive high saline groundwater circulation rates that cannot be predicted by equivalent homogeneous models results suggest that these phenomena may be common along continental shelves potentially altering estimates of ocean chemical budgets and impacting coastal water management for future generations

sediment supply as a control on the variability of sequences an example from the late namurian of northern england currently variations in accommodation space are seen as the major control on facies stacking patterns and stratal geometries this paper emphasizes the importance of the sediment supply variable through the use of a regional stratal surface based interpretation of the late namurian stratigraphy of northern england late highstand palaeogeographies and stacking pattern variations highlight spatial and temporal variations in sediment supply which promote the contemporaneous development of prograda tional aggradational and retrogradational stacking patterns this questions the derivation of relative sea level curves from specific stacking patterns and highlights the potential for miscorrelation in areas with major sediment supply variations

use of multiple age tracers to estimate groundwater residence times and long term recharge rates in arid southern oman abstract multiple age tracers were measured to estimate groundwater residence times in the regional aquifer system underlying southwestern oman this area known as the najd is one of the most arid areas in the world and is planned to be the main agricultural center of the sultanate of oman in the near future the three isotopic age tracers 4 he 14 c and 36 cl were measured in waters collected from wells along a line that extended roughly from the dhofar mountains near the arabian sea northward 400 km into the empty quarter of the arabian peninsula the wells sampled were mostly open to the umm er radhuma confined aquifer although some were completed in the mostly unconfined rus aquifer the combined results from the three tracers indicate the age of the confined groundwater is 100 ka in the central section north of the mountains and up to and one ma in the empty quarter the 14 c data were used to help calibrate the 4 he and 36 cl data mixing models suggest that long open boreholes north of the mountains compromise 14 c only interpretations there in contrast to 4 he and 36 cl calculations that are less sensitive to borehole mixing thus only the latter two tracers from these more distant wells were considered reliable in addition to the age tracers 2 h and 18 o data suggest that seasonal monsoon and infrequent tropical cyclones are both substantial contributors to the recharge the study highlights the advantages of using multiple chemical and isotopic data when estimating groundwater travel times and recharge rates and differentiating recharge mechanisms

characterisation and high resolution sequence stratigraphy of storm dominated braid delta and shoreface sequences from the basal grit group namurian of the south wales variscan peripheral foreland basin sedimentological studies of basal grit successions indicate that they were deposited in braid deltas that prograded into a storm dominated shallow marine ramp type environment high resolution sequence stratigraphy data and concepts have been used to subdivide the strata into fourth order systems tracts and longer period third order sequence sets falling stage and lowstand deposits of forced regressions are recorded by a variety of sharp based incised sandstone bodies transgressive phases by thin marine bands with high gamma ray values and highstands by coarsening upward parasequences incised lowstand sandstone bodies are particularly well represented and these have frequently removed underlying highstand and transgressive deposits their predominance is considered to be related to high sediment flux and slow basin subsidence the latter frequently being balanced or outpaced by glacio eustatic sea level falls resulting in the creation of limited to negative accommodation space synsedimentary tectonics have frequently overprinted the effects of glacio eustatic sea level changes the complex interplay between these allogenic processes was a direct result of repeated gondwana glaciations slow sea level falls and melt outs rapid sea level rises and the location of the depositional site on the cratonic side of a variscan foreland basin the tectono eustatic depositional model proposed in this case study is considered as an analogue for a number of hydrocarbon bearing sequences

structural controls on palaeozoic basin evolution and inversion in southwest wales the tectonic evolution of sw dyfed is presented in terms of a model of basin evolution and subsequent destruction by reactivation of the basin bounding faults in contractional mode movements along long lived palaeozoic extensional faults were reversed during variscan compression with the pre existing faults accommodating the contraction in addition to the development of a thin skinned thrust and fold system basin analysis of the pre variscan extensional system uses sedimentological and stratigraphical evidence to constrain the timing of movements of the basin bounding faults thus allowing division of the stratigraphy into depositional megasequences related to these extensional movements field examples on all scales illustrate active extension during the palaeozoic structural cross sections through sw dyfed demonstrate the interrelationship of the extensional and contractional deformations with palinspastic restorations of the cross sections illustrating the complexity of the pre variscan template

soil profile evolution following land use change implications for groundwater quantity and quality soil and vadose zone profiles are used as an archive of changes in groundwater recharge and water quality following changes in land use in an area of the loess plateau of china a typical rain fed loess terrace agriculture region in hequan guyuan is taken as an example and multiple tracers chloride mass balance stable isotopes tritium and water chemistry are used to examine groundwater recharge mechanisms and to evaluate soil water chloride as an archive for recharge rate and water quality results show that groundwater recharge beneath natural uncultivated grassland used as a baseline is about 94 100 mm year 1 and that the time it takes for annual precipitation to reach water table through the thick unsaturated zone is from decades to hundreds of years tritium free this recharge rate is 2 3 orders of magnitude more than in the other semiarid areas with similar annual rainfall but with deep rooted vegetation and relatively high temperature most of the water that eventually becomes recharge originally infiltrated in the summer months the conversion from native grassland to winter wheat has reduced groundwater recharge by 42 50 50 55 mm year 1 for recharge and the conversion from winter wheat to alfalfa resulted in a significant chloride accumulation in the upper soil zone which terminated deep drainage the paper also evaluates the time lag between potential recharge and actual recharge to aquifer and between increase in solute concentration in soil moisture and that in the aquifer following land use change due to the deep unsaturated zone copyright 2012 john wiley sons ltd

approach to saturation analysis of hysteresis measurements in rock magnetism and evidence for stress dominated magnetic anisotropy in young mid ocean ridge basalt abstract young mid ocean ridge basalts contain titanomagnetite crystals of varying size and composition many studies of their hysteresis properties have found m rs m s ratios considerably above the theoretical limit of 0 5 for uniaxial single domain particles since titanomagnetite is a cubic mineral high m rs m s could occur due to cubic anisotropy which allows for m rs m s values up to 0 866 on the other hand titanomagnetites with high ti content possess extremely large magnetostriction constants already slight internal stress easily outweighs cubic anisotropy and enforces uniaxial behavior are high m rs m s ratios now a proof for very low internal stress no on the contrary previous studies on synthetic titanomagnetite with high m rs m s show that after annealing this ratio decreases a possible explanation is that insufficient saturation of the hysteresis loop used to infer m rs m s leads to underestimation of m s here a systematic experimental study on a young mid ocean ridge basalt using fields of up to 7 t demonstrates that indeed the m rs m s ratio of the single domain fraction does not significantly deviate from the theoretical value of 0 5 for uniaxial anisotropy it is further estimated that internal stress above 200 mpa is necessary to explain the observed hysteresis behavior a value which is consistent with recent independent approximations on the other hand theoretical loops for cubic minerals do not fit the observed data in order to assess the validity of m s determinations from hysteresis measurements an improved method to evaluate the approach to saturation behavior of hysteresis loops is developed it allows to recognize insufficiently saturated loops and thereby helps to avoid misinterpretation of standard m rs m s measurements when high fields are not accessible

closing the sea level budget on a regional scale trends and variability on the northwestern european continental shelf long term trends and decadal variability of sea level in the north sea and along the norwegian coast have been studied over the period 1958 2014 we model the spatially nonuniform sea level and solid earth response to large scale ice melt and terrestrial water storage changes gps observations corrected for the solid earth deformation are used to estimate vertical land motion we find a clear correlation between sea level in the north sea and along the norwegian coast and open ocean steric variability in the bay of biscay and west of portugal which is consistent with the presence of wind driven coastally trapped waves the observed nodal cycle is consistent with tidal equilibrium we are able to explain the observed sea level trend over the period 1958 2014 well within the standard error of the sum of all contributing processes as well as the large majority of the observed decadal sea level variability

hydrochemical changes due to intensive use of groundwater in the carbonate aquifers of sierra de estepa seville southern spain summary the carbonate aquifers of sierra de estepa situated in southern spain are undergoing intensive groundwater exploitation consequently the volume of pumping surpasses the average recharge for periods of several consecutive years under such conditions nearby springs have either dried up or only function during short time periods after very rainy episodes followed by long droughts during the brief periods when the springs are active their water and the water extracted by pumping are calcium bicarbonates with a spatial temporal variability of their physico chemical characteristics that is mainly conditioned by the degree of functional karstification of each system when the springs are inactive the pumping water gradually increases in salinity and becomes hco 3 clcana clhco 3 naca and clna under the new conditions caused by so much pumping the main factors determining the hydrochemical changes are the mixing of waters and the subsequent reactions of dissolution precipitation between 1 the recharge coming from rainwater 2 the hypersaline inputs from the clay evaporite aquitards situated on the edges and at the base of the aquifer and 3 the water stored in each aquifer the hydrochemical information acquired allowed us to characterize and model the groundwater of these aquifers to study the causes of its great spatial and temporal variability and explain the influence of exploitation this research shows that making sustainable use of water resources associated with carbonate aquifers calls for sound knowledge of the relationship between the aquifer and other bodies of groundwater or surface water the hydrochemical quality of these possible inputs and the vulnerability of the aquifer to exploitation which in turn is conditioned by the ratio between water reserves and recharge

palaeohydrological characteristics and palaeogeographic reconstructions of incised valley fill systems insights from the namurian successions of the united kingdom and ireland namurian carboniferous eustatic fluctuations drove the incision and backfill of shelf crossing valley systems located in humid subequatorial regions which are now preserved in successions of the united kingdom and ireland the infills of these valleys archive the record of palaeoriver systems whose environmental hydrological and palaeogeographic characteristics remain unclear a synthesis of sedimentological data from fluvial strata of 18 namurian incised valley fills in the united kingdom and ireland is undertaken to elucidate the nature of their formative river systems and to refine regional palaeogeographic reconstructions quantitative analyses are performed of facies proportions of geometries of incised valley fills and related architectural elements and of the thickness of dune scale sets of cross strata reconstruction of the size of the drainage areas that fed these valleys is attempted based on two integrative approaches flow depth estimations from dune scale cross set thickness statistics and scaling relationships of incised valley fill dimensions derived from late quaternary examples the facies organization of these incised valley fills suggests that their formative palaeorivers were perennial and experienced generally low discharge variability consistent with their climatic context however observations of characteristically low variability in cross set thickness might reflect rapid flood recession perhaps in relation to sub catchments experiencing seasonal rainfall variations in facies characteristics including inferences of flow regime and cross set thickness distributions might reflect the control of catchment size on river hydrology the degree to which is considered in light of data from modern rivers palaeohydrological reconstructions indicate that depth estimations from cross set thickness contrast with observations of barform and channel fill thickness and projected thalweg depths exceed the depth of some valley fills limitations in data and interpretations and high bedform preservation are recognized as possible causes with consideration of uncertainties in the inference of catchment size the palaeogeography of the valley systems has been tentatively reconstructed by integrating existing provenance and sedimentological data the approaches illustrated in this work can be replicated to the study of palaeohydrological characteristics and palaeogeographic reconstructions of incised valley fills globally and through geological time

late yeadonian upper sandstone group incised valley supply and depositional systems in the south wales peripheral foreland basin implications for the evolution of the culm basin and for the silesian hydrocarbon plays of onshore and offshore uk abstract the upper sandstone group of south wales has previously been interpreted as a simple nnw sse trending incised valley that was filled during the late yeadonian namurian g1b data presented in this study indicate a far more complex scenario the group is well developed in the pembrokeshire sub basin but it is absent from the main part of the south wales basin located to the east of the penlan axis the principal source area for sediment flux was the forebulge of the basin located to the north in lower palaeozoic foreland strata variscan flexural uplift of this source area and an accompanying rapid high magnitude fall in sea level produced a very high sediment budget thus during the late yeadonian lowstand of sea level massive amounts of sediment were being generated and transported via an incised valley system across the western part of the south wales peripheral foreland basin the location and orientation of the incised supply system and its related interfluves were controlled by intrabasinal synsedimentary variscan structures many of which were reactivated caledonian extensional faults during the succeeding sea level rise the incised valley was filled initially by fluvio deltaic sands and later by estuarine argillaceous sediments the implications of this combined tectonic sedimentological high resolution sequence stratigraphic model for the evolution of the late namurian crackington formation turbidites of the culm basin are discussed examples of silesian incised valley fill sandstone reservoirs developed in the east midlands oilfield and the southern gas basin are briefly summarised and their spatial and temporal distributions are appraised data generated from these case studies are assessed in terms of their use for the modelling of incised valley fill sequences in foreland basins and other tectonic settings

an objective frequency domain method for quantifying confined aquifer compressible storage using earth and atmospheric tides the groundwater hydraulic head response to the worldwide and ubiquitous atmospheric tide at 2 cycles per day cpd is a direct function of con ned aquifer compressible storage the ratio of the responses of hydraulic head to the atmospheric pressure change is a measure of aquifer barometric e ciency from which formation compressibility and aquifer speci c storage can be determined in situ rather than resorting to laboratory or aquifer pumping tests the earth tide also impacts the hydraulic head response at the same frequency and a method is developed here to quantify and remove this interference as a result the barometric e ciency can be routinely calculated from 6 hourly hydraulic head atmospheric pressure and modeled earth tide records where available for a minimum of 15 days duration this new approach will be of critical importance in assessing worldwide problems of land subsidence or groundwater resource evaluation that both occur due to groundwater abstraction

contribution of global groundwater depletion since 1900 to sea level rise 1 removal of water from terrestrial subsurface storage is a natural consequence of groundwater withdrawals but global depletion is not well characterized cumulative groundwater depletion represents a transfer of mass from land to the oceans that contributes to sea level rise depletion is directly calculated using calibrated groundwater models analytical approaches or volumetric budget analyses for multiple aquifer systems estimated global groundwater depletion during 1900 2008 totals 4 500 km3 equivalent to a sea level rise of 12 6 mm 6 of the total furthermore the rate of groundwater depletion has increased markedly since about 1950 with maximum rates occurring during the most recent period 2000 2008 when it averaged 145 km3 yr equivalent to 0 40 mm yr of sea level rise or 13 of the reported rate of 3 1 mm yr during this recent period

storm and tide dominated shorelines in cretaceous moosebar lower gates interval outcrop equivalents of deep basin gas trap in western canada the moosebar and gates formations crop out in the deformed foothills belt south of fort st john british columbia they permit examination of the depositional environments of sandstones and conglomerates that are gas bearing in the equivalent wilrich falher interval of the deep basin of alberta and british columbia the moosebar gates interval consists of several upward coarsening and marine to nonmarine sequences moosebar bioturbated shales pass upward into turbidites and offshore storm deposits flow directions indicate a north dipping paleoslope a second coarsening upward sequence at the top of the moosebar and base of the gates terminates in a lenticular fluvial conglomerate up to 30 m thick which is overlain by coals carbonaceous mudstones and sandstones above the carbonaceous zone a major lateral facies change is observed fluvial conglomerates in the south grade into beach conglomerates northward the upper part of the beach conglomerate consists of exposed three dimensional storm berms at least 500 m long up to 1 5 m high with wavelengths of 12 to 24 m the berms trend east west seaward of the conglomerate beach are herringbone cross bedded tidal sandstones with a marine trace fauna graded sharp based conglomerates also are present probably washed out to sea by storms farther north at the same stratigraphic level is a series of partly overlapping conglomerate bars up to 5 m thick and 40 to 50 m across the tops of these bars are covered with storm formed symmetric conglomeratic dunes details of the orientation and geometry of these conglomerate bodies along with their internal structure and pebble fabrics suggest that four major environments fluvial beach offshore conglomerate bars and offshore graded storm conglomerates should be identifiable and predictable in the subsurface

evolving fluvial style in the kekiktuk formation mississippian endicott field area alaska base level response to contemporaneous tectonism the hydrocarbon reservoir at endicott field offshore from the sagavanirktok delta in northeastern alaska is found in the upper mississippian visean kekiktuk formation the trap is bounded by the northwest southeast trending tigvariak and mikkelson bay faults and the younger east west trending niakuk fault the kekiktuk comprises sandstones siltstones and mudstones with locally significant coals and conglomerates and is subdivided into three major reservoir zones based on the relative dominance of these lithologies zone 1 the lowest comprises mudstones siltstones and coals with subordinate isolated sandstones and represents deposition within a low lying swamp plain with very low net to gross ratio this zone is considered to be effectively nonreservoir major movement on the mikkelson bay and tigvariak faults created a half graben with uplift to the north and east and a very significant drop in base level this change resulted in fairly widespread deposition of zone 2 medium to coarse grained sandstones from sandy bed load braided streams however those sandstones thin significantly to the west away from the faults continuing tectonism at this time created local shifts in base level manifest as diversion of streams widespread abandonment and subsidence leading to the creation of a arge lake the lacustrine deposits are widespread and effectively divide zone 2 into two subzones those subzones are mappable sheet sandstones and constitute the best reservoir at endicott field in terms of net to gross ratio porosity permeability and sandstone connectivity base level shows evidence of rising dramatically at the end of zone 2 this rise is attributed to continuing tectonism within the basin and is particularly associated with the east west trending mid field fault system at endicott field as well as ongoing activity on the tigvariak mikkelson bay fault system thus at the base of zone 3 subzone 3a in the southern and eastern parts of the field the rocks are mudstones and widespread coals and contain at least one unequivocally marine mudstone these rocks are lower delta plain interdistributary bay fill deposits with rare distributary channel sandstones north and west of the mid field fault system the marine mudstone is absent and the facies changes significantly with the loss of dominant coal and a concomitant increase of dist ibutary channel sandstones reservoir properties of subzone 3a including connectivity are significantly different in this area subzone 3b is a thick accumulation of fine grained alluvial overbank deposits within which occur rare isolated anastomosed channel sandstones of limited connectivity this subzone makes minimal contribution to endicott field reserves subzone 3c is characterized particularly in its upper part by well developed fining upward cycles indicating mature meandering streams the relationships between these two highest subzones of the kekiktuk at endicott field indicate they represent an aggradational episode initiated by tectonically induced avulsion and set against a background of rising base level to the west at some distance from the tigvariak mikkelson bay f ult system zone 3 is much thinner than at endicott field and is dominated by mudstones and coals this evidence emphasizes the control that contemporaneous tectonism related to those faults had on sediment especially sandstone distribution within the kekiktuk formation base level changes can be identified within the end page 1723 kekiktuk formation in the north slope subsurface by careful lithofacies analysis and an awareness of key constraining indicators such as are revealed by palynology paleontology and structural geology by analogy with shallow marine rocks sequence stratigraphic concepts may be extended to continental successions however one must approach such problems with a full awareness of the impact of tectonism on base level and basin development

structural controls on upper palaeozoic sedimentation in south east wales marked thickness changes in early dinantian courceyan chadian sediments occur across the cardiff cowbridge anticline a major east west variscan fold in the vale of glamorgan they resulted from differential subsidence over an active concealed basement fault zone the vale of glamorgan axis which is coincident with the hinge of the anticline the latter formed in response to inversion on this basement fault a caledonian ancestry for the vale of glamorgan axis is indicated by pronounced upper old red sandstone overstep across it across the severn estuary between south wales and the bristol mendips region there is a significant offset of isopachs and facies belts in both the courceyan chadian and arundian sequences it is suggested that these result from intra carboniferous dextral strike slip along a major fault zone underlying the severn estuary the severn estuary fault zone and that the vale of glamorgan axis was a synthetic structure developed in conjunction with this strike slip movement by inference the severn estuary fault zone shares a common history with the vale of glamorgan axis extending back to the devonian and possibly earlier late dinantian holkerian facies distribution reflects uplift and emergence on the north south usk anticline and malvern lineament continued uplift is recorded in silesian sequences in south east wales and the bristol mendips area the orientation of structures bordering the severn estuary is consistent with their development in a right lateral strike slip zone

estimates of twenty first century sea level changes for norway in this work we establish a framework for estimating future regional sea level changes for norway following recently published works we consider how different physical processes drive non uniform sea level changes by accounting for spatial variations in 1 ocean density and circulation 2 ice and ocean mass changes and associated gravitational effects on sea level and 3 vertical land motion arising from past surface loading change and associated gravitational effects on sea level an important component of past and present sea level change in norway is glacial isostatic adjustment central to our study therefore is a reassessment of vertical land motion using a far larger set of new observations from a permanent gnss network our twenty first century sea level estimates are split into two parts firstly we show regional projections largely based on findings from the fourth assessment report of the intergovernmental panel on climate change ipcc ar4 and dependent on the emission scenarios a2 a1b and b1 these indicate that twenty first century relative sea level changes in norway will vary between 0 2 to 0 3 m 1 sigma 0 13 m secondly we explore a high end scenario in which a global atmospheric temperature rise of up to 6 c and emerging collapse for some areas of the antarctic ice sheets are assumed using this approach twenty first century relative sea level changes in norway are found to vary between 0 25 and 0 85 m min max 0 45 m we attach no likelihood to any of our projections owing to the lack of understanding of some of the processes that cause sea level change

a data driven model for constraint of present day glacial isostatic adjustment in north america abstract geodetic measurements of vertical land motion and gravity change are incorporated into an a priori model of present day glacial isostatic adjustment gia in north america via least squares adjustment the result is an updated gia model wherein the final predicted signal is informed by both observational data and prior knowledge or intuition of gia inferred from models the data driven method allows calculation of the uncertainties of predicted gia fields and thus offers a significant advantage over predictions from purely forward gia models in order to assess the influence each dataset has on the final gia prediction the vertical land motion and grace measured gravity data are incorporated into the model first independently i e one dataset only then simultaneously the relative weighting of the datasets and the prior input is iteratively determined by variance component estimation in order to achieve the most statistically appropriate fit to the data the best fit model is obtained when both datasets are inverted and gives respective rms misfits to the gps and grace data of 1 3 mm yr and 0 8 mm yr equivalent water layer change non gia signals e g hydrology are removed from the datasets prior to inversion the post fit residuals between the model predictions and the vertical motion and gravity datasets however suggest particular regions where significant non gia signals may still be present in the data including unmodeled hydrological changes in the central prairies west of lake winnipeg outside of these regions of misfit the posterior uncertainty of the predicted model provides a measure of the formal uncertainty associated with the gia process results indicate that this quantity is sensitive to the uncertainty and spatial distribution of the input data as well as that of the prior model information in the study area the predicted uncertainty of the present day gia signal ranges from 0 2 1 2 mm yr for rates of vertical land motion and from 3 4 mm yr of equivalent water layer change for gravity variations

sea level rise and coastal circulation controlled holocene groundwater development in bermuda and caused a meteoric lens to collapse 1600 years ago abstract the recent report from working group ii of the intergovernmental panel on climate change ipcc called for an increased understanding of how groundwater interacts with the ocean atmospheric system this remains a prerequisite to better understand how groundwater will respond to climate change however achieving this goal is hampered by several problems including 1 our minimal understanding of how current groundwater conditions evolved and responded to previous climatic perturbations and 2 the scarcity of techniques available for evaluating prehistoric groundwater subfossil benthic foraminifera in underwater caves are an overlooked method of evaluating prehistoric groundwater on coastal carbonate terrain because they provide a proxy for groundwater salinity and circulation twelve radiocarbon dates and foraminiferal paleoecology from two sediment cores obtained from green bay cave gbc bermuda provide the first holocene scale groundwater reconstruction first the cave floor 20 7 mbsl was flooded at 7 7 ka as north atlantic sea level and groundwater rose in near synchrony over the holocene groundwater conditions salinity circulation and degree of oxygenation shifted a minimum of five times primarily in response to sea level rise most importantly we provide evidence that a prehistoric meteoric lens collapsed at 1 6 ka as sea level rise breached a local sill and completely altered bermudian coastal circulation the complete loss or retreat of a groundwater mass associated with a minor sea level change validates some numerical predictions that small changes in sea level can destabilize coastal groundwater resources when coastal geometry and circulation are considered

the rapid yet uneven turnover of earth s groundwater the turnover of groundwater through recharge drives many processes throughout earth s surface and subsurface yet groundwater turnover rates and their relationship to regional climate and geology remain largely unknown we estimated that over 200 million km3 of groundwater has recharged since the last glacial maximum lgm which is ten times the volume of global groundwater storage however flushing is very unevenly distributed throughout earth s one million watersheds with some aquifers turned over thousands of times to others with 1 turnover the median global groundwater turnover of 5 3 times since the lgm highlights groundwater s active role in earth system processes incomplete groundwater turnover since the lgm beneath a third of land areas reveals the imprint of relict climate conditions on modern day groundwater resources the bulk groundwater turnover calculated here enable better quantification of groundwater s impact in dynamic global water budgets and the transport of nutrients contaminants and geologic weathering products

spectral gamma ray characterization of high resolution sequence stratigraphy examples from upper carboniferous fluvio deltaic systems county clare ireland the application of high resolution sequence stratigraphy requires the ability to recognize key surfaces which record fluctuations in relative sea level in sub surface studies gamma ray logs have been used to identify maximum flooding surfaces but their full potential has not been realized gamma ray profiles produced using a portable spectrometer on exposed upper carboniferous fluvio deltaic deposits in western ireland reveal that key surfaces and systems tracts can be characterized more comprehensively and recognized with greater confidence if spectral gamma ray data k u th and their respective ratios are used in conjunction with traditional total count data maximum flooding surfaces can be distinguished from lesser flooding surfaces by a distinctive u peak 5 ppm and low th u ratio 6 laterally correlative interfluves are represented by distinctive palaeosols that can be clearly identified in spectral gamma ray data by their anomalously low k content 17 finally the stacking pattern of parasequence sets can be identified using the trends of th k ratios from sandstones in successive parasequences these results have widespread implications for the recognition of high resolution sequence stratigraphic signatures in the stratigraphic record with particular reference to the subsurface analysis of fluvio deltaic deposits

sand body orientation palaeoslope analysis and basin fill implications in the westphalian a c of great britain channel orientation and palaeoflow analyses across the british westphalian carboniferous coalfields show that three main inflow directions dominated the palaeogeography from the mid langsettian to the mid bolsovian in eastern scotland and ne england flow was mainly from the n and ne in the pennine basin of north central england flow was mainly from the w and nw whilst in south wales main flow from the sw was compatible with a westerly system that also branched to give the northerly inflows recorded in the culm basin of southwest england the depositional area included discrete tectonic depocentres notably the pennine basin which was traversed directly and tangentially by major channel belts these basins were essentially incidental to the main channel pathways but sand body characteristics vary according to basin location a new depositional model for the post rift pennine basin is proposed relating sand concentrations and connectivities to the depositional and tectonic setting the description of dominant sw to ne flow across south wales through much of the langsettian and duckmantian in contrast to the centripetal inflows previously proposed implies some similar channel depocentre relationships to those described here for the pennine basin

seismic facies analysis of westphalian sequences of the southern north sea abstract differing seismic facies are observed from within the westphalian sequences of the southern north sea a review of published synthetic seismograms and seismic data from known coal bearing basins establishes seismic facies types and their relationships similar reflection character is recognized from westphalian sequences in the southern north sea and lithologies confirmed by borehole information probable sand silt or clastic prone upper coal measures westphalian c d stages and coal prone lower and middle coal measures westphalian a b and part c stages can be defined and mapped providing information on the regional distribution of source and reservoir rocks and stratigraphic plays it is suggested that sand prone channel complexes or clastic dominated areas within the mainly a b stages can be recognized and mapped providing information on migration pathways and stratigraphic plays

sedimentology of the rough rock a carboniferous braided river sheet sandstone in northern england the rough rock is a coarse grained fluvial sheet sandstone which outcrops across northern and central england it is interpreted as a braided river sandstone on the basis of sedimentary structures internal erosion and growth surfaces this study reveals that the rough rock represents more than a single phase of deposition and that internal erosion surfaces may indicate anabranch avulsions or more significant river avulsions detailed outcrop profiles are presented to try and distinguish the styles of deposition and the nature of internal bounding surfaces and channel geometry the rough rock formation contains a very large number of first and third order bedding contacts which represent the migration of dunes and channels respectively there are relatively few macroforms and bars preserved the lack of second order surfaces within many outcrops could indicate that bars in the rough rock rivers were very large and therefore cannot be resolved at the outcrop scale similarly the rivers which deposited the rough rock may have had such high width depth ratios that the dip of second order bounding surfaces are too low to be identified the large number of third order bounding surfaces indicates channel stacking which may have occurred in two ways 1 relocation of rivers in the same area over time or 2 anabranch avulsion within a braided river within a hierarchy of channels the problems associated with differentiating between these two mechanisms are discussed 1993 the geological society

imprint of long term solar signal in groundwater recharge fluctuation rates from northwest china multiple spectral and statistical analyses of a 700 yearlong temporal record of groundwater recharge from the dry lands badain jaran desert inner mongolia of northwest china reveal a stationary harmonic cycle at 200 20 year interestingly the underlying periodicity in groundwater recharge fluctuations is similar to those of solar induced climate cycle suess wiggles and appears to be coherent with phases of the climate fluctuations and solar cycles matching periodicity of groundwater recharge rates and solar and climate cycles renders a strong impression that solar induced climate signals may act as a critical amplifier for driving the underlying hydrographic cycle through the common coupling of long term sun climate groundwater linkages

anthropogenic impacts on mass change in north china the gravity fields from the gravity recovery and climate experiment grace satellite have been used to estimate groundwater depletion in many parts of the world groundwater depletion assessment in north china however is affected by large anthropogenic disturbance on mass variation using the water survey data and coal flow statistics we show that the mass variations in north china during 2003 2011 were largely affected by reservoir regulation water diversion and coal transport according to our estimates the mass loss rate of groundwater depletion 14 to 8 4 mm yr 1 was largely offset by the mass gains caused by reservoir regulation 1 3 mm yr 1 water diversion 4 4 mm yr 1 and coal transport 1 9 mm yr 1 in the north china plain we note that anthropogenic impacts on mass change must be taken into account when using the grace data to estimate groundwater change in the area intensively altered by human activities 2013 american geophysical union all rights reserved

global depletion of groundwater resources 1 in regions with frequent water stress and large aquifer systems groundwater is often used as an additional water source if groundwater abstraction exceeds the natural groundwater recharge for extensive areas and long times overexploitation or persistent groundwater depletion occurs here we provide a global overview of groundwater depletion here defined as abstraction in excess of recharge by assessing groundwater recharge with a global hydrological model and subtracting estimates of groundwater abstraction restricting our analysis to sub humid to arid areas we estimate the total global groundwater depletion to have increased from 126 32 km3 a 1 in 1960 to 283 40 km3 a 1 in 2000 the latter equals 39 10 of the global yearly groundwater abstraction 2 0 6 of the global yearly groundwater recharge 0 8 0 1 of the global yearly continental runoff and 0 4 0 06 of the global yearly evaporation contributing a considerable amount of 0 8 0 1 mm a 1 to current sea level rise

correlation of the rhenohercynian variscides recent structural and stratigraphical data from the rhenohercynian variscides of belgium germany and south cornwall indicate tectonic continuity within this zone prior to disruption along a late carboniferous dextral transcurrent fault this extends from the bristol channel to the vosges parallel to similar lineaments of variscan age in europe and north america consequently a tectonic model for south cornwall is extrapolated to europe and a plate tectonic setting for the evolution of the north european variscides by the closure of an oceanic basin is discussed

semiempirical and process based global sea level projections we review the two main approaches to estimating sea level rise over the coming century physically plausible models of reduced complexity that exploit statistical relationships between sea level and climate forcing and more complex physics based models of the separate elements of the sea level budget previously estimates of future sea level rise from semiempirical models were considerably larger than those from process based models however we show that the most recent estimates of sea level rise by 2100 using both methods have converged but largely through increased contributions and uncertainties in process based model estimates of ice sheets mass loss hence we focus in this paper on ice sheet flow as this has the largest potential to contribute to sea level rise progress has been made in ice dynamics ice stream flow grounding line migration and integration of ice sheet models with high resolution climate models calving physics remains an important and difficult modeling issue mountain glaciers numbering hundreds of thousands must be modeled by extensive statistical extrapolation from a much smaller calibration data set rugged topography creates problems in process based mass balance simulations forced by regional climate models with resolutions 10 100 times larger than the glaciers semiempirical models balance increasing numbers of parameters with the choice of noise model for the observations to avoid overfitting the highly autocorrelated sea level data all models face difficulty in separating out non climate driven sea level rise e g groundwater extraction and long term disequilibria in the present day cryosphere sea level system

uncertainty in global groundwater storage estimates in a total groundwater stress framework groundwater resilience is defined and quantified with remote sensing from gracetimescales of aquifer depletion are assessed as a total groundwater stress ratiothe volume of usable global groundwater storage is found to be largely unknown

review short term sea level changes in a greenhouse world a view from the cretaceous abstract this review provides a synopsis of ongoing research and our understanding of the fundamentals of sea level change today and in the geologic record especially as illustrated by conditions and processes during the cretaceous greenhouse climate episode we give an overview of the state of the art of our understanding on eustatic global versus relative regional sea level as well as long term versus short term fluctuations and their drivers in the context of the focus of unesco iugs igcp project 609 on cretaceous eustatic short term sea level and climate changes we evaluate the possible evidence for glacio eustasy versus alternative or additional mechanisms for continental water storage and release for the cretaceous greenhouse and hothouse phases during which the presence of larger continental ice shields is considered unlikely increasing evidence in the literature suggests a correlation between long period orbital cycles and depositional cycles that reflect sea level fluctuations implying a globally synchronized forcing of eustatic sea level fourth order depositional sequences seem to be related to a 405 ka periodicity which most likely represents long period orbital eccentricity control on sea level and depositional cycles third order cyclicity expressed as time synchronous sea level falls of 20 to 110 m on 0 5 to 3 0 ma timescales in the cretaceous are increasingly recognized as connected to climate cycles triggered by long term astronomical cycles that have periodicity ranging from 1 0 to 2 4 ma future perspectives of research on greenhouse sea level changes comprise a high precision time scale for sequence stratigraphy and eustatic sea level changes and high resolution marine to non marine stratigraphic correlation

groundwater acidification near the water table of the superficial aquifer gnangara mound swan coastal plain western australia abstract this study improves the spatial understanding of the magnitude of the groundwater acidification issue in a poorly buffered sandy aquifer in western australia the study provides more information to assess the risk the acidification poses to groundwater dependent ecosystems of the gnangara mound groundwater acidification ph so 4 2 cl ratios 0 5 mg l units low ca to al molar ratios and elevated concentrations of al and fe acidic groundwater in the capture zones of wetlands may pose a long term risk to ecological values acidic groundwater in poorly buffered systems also poses a risk for users of untreated groundwater land and water use management should consider poorly buffered aquifers to be highly sensitive particularly where rainfall and recharge trends have declined over a period of time a comprehensive and consistent groundwater sampling program should be developed to fully delineate the groundwater acidification issue near the water table of the gnangara mound to assist the formulation of groundwater allocation plans

potential for bias in 21st century semiempirical sea level projections we examine the limitations of a semiempirical model characterized by a sea level projection of 73 cm with rcp4 5 scenario by 2100 calibrating the model with data to 1990 and then simulating the period 1993 2009 produces sea level in close agreement with acceleration in sea level rise observed by satellite altimetry nonradiative forcing contributors such as long term adjustment of greenland and antarctica ice sheets since last glacial maximum abyssal ocean warming and terrestrial water storage may bias model calibration which if corrected for tend to reduce median sea level projections at 2100 by 2 10 cm though this is within the confidence interval we apply the semiempirical approach to simulate individual contributions from thermal expansion and small glacier melting steric sea level projections agree within 3 cm of output from process based climate models in contrast semiempirical simulation of melting from glaciers is 26 cm which is twice large as estimates from some process based models however all process models lack simulation of calving which likely accounts for 50 of small glacier mass loss worldwide furthermore we suggest that changes in surface mass balance and dynamics of greenland ice sheet made contributions to the sea level rise in the early 20th century and therefore are included within the semiempirical model calibration period and hence are included in semiempirical sea level projections by 2100 antarctic response is probably absent from semiempirical models which will lead to a underestimate in sea level rise if as is probable antarctica loses mass by 2100

is the welsh borderland fault system a terrane boundary the welsh borderland fault system forms one of the most prominent tectonic lines in southern britain and along with the menai straits and malverns fault systems is a candidate for a terrane boundry a review of stratigraphic linkage across the system reveals significant contrasts in pre ashgill sequences these contrasts occur particularly across its north west edge the pontesford and tywi lineaments rather than across the church stretton lineament the ashgill event produced strike slip dominated structure and an unconformity that expands from the welsh basin towards the platform an important linkage sequence was produced by the subsequent late ashgill to llandovery marine transgression across the fault system silurian facies changes are marked but gradational and no more than expected across a basin margin from stable to thinned crust devonian acadian sinistral transpression and later phanerozoic movements reactivated the fault system but did not engineer major terrane amalgamation across it this reactivation has obscured the early history of the fault system the remaining evidence admits though does not prove major ashgill or earlier transcurrent movements broader considerations suggest that the welsh borderland fault system originated either as a cambro ordovician extensional system on the south eastern margin of the welsh basin or during late precambrian early cambrian transcurrent movements occurring within avalonia inboard from the menai strait line

groundwater recharge assessment at local and episodic scale in a soil mantled perched karst aquifer in southern italy summary groundwater recharge assessment of karst aquifers at various spatial and temporal scales is a major scientific topic of current importance since these aquifers play an essential role for both socio economic development and fluvial ecosystems in this study groundwater recharge was estimated at local and episodic scales in a representative perched karst aquifer in a region of southern italy with a mediterranean climate the research utilized measurements of precipitation air temperature soil water content and water table depth obtained in 2008 at the acqua della madonna test area terminio mount karst aquifer campania region at this location the aquifer is overlain by ash fall pyroclastic soils the episodic master recession emr method an improved version of the water table fluctuation wtf method was applied to estimate the amount of recharge generated episodically by individual rainfall events the method also quantifies the amount of precipitation generating each recharge episode thus permitting calculation of the recharge to the precipitation ratio rpr on a storm by storm basis depending on the seasonally varying air temperature evapotranspiration and precipitation patterns calculated values of rpr varied between 35 and 97 among the individual episodes a multiple linear correlation of the rpr with both the average intensity of recharging rainfall events and the antecedent soil water content was calculated given the relatively easy measurability of precipitation and soil water content such an empirical model would have great hydrogeological and practical utility it would facilitate short term forecasting of recharge in karst aquifers of the mediterranean region and other aquifers with similar hydrogeological characteristics by establishing relationships between the rpr and climate dependent variables such as average storm intensity it would facilitate prediction of climate change effects on groundwater recharge the emr methodology could further be applied to other aquifers for evaluating the relationship of recharge to various hydrometeorological and hydrogeological processes

palaeomagnetism of the early devonian lower old red sandstones of south wales implications to variscan overprinting and differential regional rotations component structures of magnetic remanence in the old red sandstones of south wales are related to tectonic history by detailed study of three contrasting areas 1 remote from 2 bordering and 3 within the variscan orogenic belt a uniform southerly shallow directed component dominates remanence in each sector in area 1 where it is considered most representative of the regional field this magnetisation has a mean di 191 1 8 0 151 samples in situ 95 2 equivalent to a pole position at 341 1 e 41 2 s fold tests show that it was acquired at an intermediate stage of orogenesis and during the carboniferous permian reversed superchron it is interpreted as a pervasive magnetic overprint imparted by northward fluid migration consequent upon loading of the orogen to the south remote from the orogenic front a higher blocking temperature dual polarity remanence of probable lower devonian age has sporadically survived di 246 38 27 samples tilt adjusted 95 7 2 corresponding to a pole position at 297 e 3 n this remanence is entirely replaced close to the frontal zone of the orogen within the orogen low blocking temperature components are more prominent and chemical alteration obscures the highest blocking temperature portion of the remanence spectrum this region was deformed into upright folds before the magnetising event following remanence acquisition continuing deformation produced asymmetry in fold structure producing a plunge and steepening of the southern limbs structures in the south were already more deformed than those in the north at the time of magnetisation implying that the causative fluid front moved northwards with time the palaeomagnetic vectors are rotated clockwise to the west in south wales and in part record the effects of regional dextral transpression the largest rotation however is observed within the same thrust block and apparent differential rotation here is probably a consequence of strain

the sedimentary record of carboniferous rivers continuing influence of land plant evolution on alluvial processes and palaeozoic ecosystems abstract evidence from modern rivers and the deep time geological record attests to the fundamental importance of plant life for the construction of physical habitats within fluvial environments data from an extensive literature review and original fieldwork demonstrates that many landforms and geomorphic features of modern river systems appear in the palaeozoic stratigraphic record once terrestrial vegetation had adopted certain evolutionary advances for example stable point bars are associated with the onset of rooted plants in the siluro devonian and avulsive and anabranching fluvial systems become common at the same time as extensive arborescent vegetation in the carboniferous in this paper we demonstrate a correlation between the diversification of physical fluvial environments and the expansion of terrestrial fauna and flora with an emphasis on the culmination of these trends within carboniferous alluvial systems many extrinsic factors have been considered as possible controls on the evolutionary timelines of terrestrialization for organisms however a fundamental prerequisite for achieving terrestrial biodiversity was the variety of physical habitats especially riparian systems available for newly evolved organisms in association with abundant lowland meandering systems the widespread appearance across carboniferous alluvial plains of fixed channel and anabranching reaches created further physical landforms for colonization and would have promoted increasingly complex hyporheic flow regimes furthermore the associated increase in arborescent vegetation and supply of large woody debris to inland and coastal rivers would have created a wealth of microhabitats for continental organisms we argue that the expanding extent and diversity of physical alluvial niches during the palaeozoic is an underappreciated driver of the terrestrialization of early continental life the study of the deep time fossil and stratigraphic record also illustrates that vegetation is a fundamental prerequisite for the creation of biogeomorphic alluvial landforms and physical habitats and microhabitats

testing the robustness of semi empirical sea level projections we determine the parameters of the semi empirical link between global temperature and global sea level in a wide variety of ways using different equations different data sets for temperature and sea level as well as different statistical techniques we then compare projections of all these different model versions over 30 for a moderate global warming scenario for the period 2000 2100 we find the projections are robust and are mostly within 20 of that obtained with the method of vermeer and rahmstorf proc natl acad sci usa 106 21527 21532 2009 namely 1 m for the given warming of 1 8 c lower projections are obtained only if the correction for reservoir storage is ignored and or the sea level data set of church and white surv geophys 2011 is used however the latter provides an estimate of the base temperature t 0 that conflicts with the constraints from three other data sets in particular with proxy data showing stable sea level over the period 1400 1800 our new best estimate model accounting also for groundwater pumping is very close to the model of vermeer and rahmstorf proc natl acad sci usa 106 21527 21532 2009

groundwater variations from autocorrelation and receiver functions 1 receiver functions at iu hkt station 2 seismic velocity perturbation data from ambient noise autocorrelation 3 synthetic receiver functions at iu hkt station

upper carboniferous fine grained turbiditic sandstones from southwest england a model for growth in an ancient delta fed subsea fan abstract the upper carboniferous crackington and bude formations of southwest england comprise laminated black mudstones gray siltstones thin medium and thick bedded sandstones and contorted silty sandstones the thick bedded sandstones only occur in the bude formation which overlies the crackington the sandstones were deposited predominantly by turbidity currents in a relatively shallow basin they are unusual for two reasons 1 sediment coarser than fine sand is entirely absent 2 unlike many previously described ancient subsea fan deposits organized bundles of sandstones displaying asymmetric upward thickening or upward thinning sequences are no more common than symmetric sequences and both types of organized bundles are much less common than disorganized nonsequential bundle particularly in the bude formation sediment was supplied directly from a delta to the north by resedimentation of delta front sands and slumping of upper pro delta muds and silts to form a lower pro delta turbidite fan fan growth is not readily explained by current models for single sourced tripartite subsea fans displaying radial growth it developed instead a bipartite growth pattern which was strongly influenced in its upper part by external variables including grain size distributary channel switching and other deltaic processes active tectonism within the basin and possibly sea level fluctuations the fan grew by down slope construction of independent levee channel complexes each of which headed in the upper pro delta and even possibly the delta front slumping and mobilization of argillaceous facies resulted in the random occurrence of contorted beds in all parts of the fan regionally extensive mudstones known as key shales within the fan deposits probably reflect large scal upslope delta lobe abandonment the crati and ebro fans of the mediterranean sea would appear to be good modern analogs for the crackington bude fan system

late carboniferous tectonic subsidence in south wales implications for variscan basin evolution and tectonic history in sw britain detailed stratigraphic data have been used to backstrip seven sections from the carboniferous south wales coal basin resulting tectonic subsidence curves for the interval 319 305 ma namurian westphalian d are convex up indicating increasing subsidence rate with time with rates between 130 and 250 m ma 1 suggesting a foreland basin setting forward modelling of subsidence due to flexural loading in front of a propagating orogenic wedge shows that an orogenic load migrating in a north northeasterly direction across sw england between 319 and 305 ma could have generated the backstripped subsidence patterns sensitivity tests show that while many of the forward model parameters are poorly constrained and the model results non unique backstripped subsidence patterns allow reasonable constraint on the different model cases so that model predictions can be treated as one possibility in a limited range the predicted load evolution is consistent with current knowledge of tectonic and stratigraphic features of sw england these results suggest that subsidence in other late carboniferous uk basins may also have been influenced by flexure due to a propagating orogenic load

drought driven transient aquifer compaction imaged using multitemporal satellite radar interferometry in unconsolidated heterogeneous aquifer systems low rates of pore pressure diffusion of applied effective stresses due to the drainage of thick low permeability clay rich layers with time constants of decades to centuries cause delayed residual permanent compaction and land subsidence current application of satellite differential radar interferometry dinsar differential interferometric synthetic aperture radar to estimate aquifer hydraulic properties compressibility and or storage in these systems is limited by the temporal availability of synthetic aperture radar data 1992 present in this paper we study the degree of aquifer compaction due to water extraction using dinsar through an example in southeast spain ground deformation data indicate large scale deformation and in particular the discovery of the highest rates of groundwater related land subsidence recorded in europe 10 cm yr affecting the guadalentin river basin 200 km 2 the largest tributary of the segura river modeling of the ground surface time series of the guadalentin basin indicates that deformation is mainly driven by nonlinear time delayed flow processes in the underlying aquifer after a drought period 1990 1995 the aquifer responded with an exponential decay of the land subsidence lasting 8 yr suggesting transient groundwater pore pressure flow we show that multitemporal satellite radar interferometry analysis and its modeling can be a stimulating way to study nonlinear soil mechanics and groundwater flows at aquifers a deeper understanding of such processes could help the management of water resources and land subsidence of unconsolidated coastal and quaternary alluvial aquifers in a highly evolving climate region the mediterranean sea and elsewhere

provenance of late carboniferous sandstones in the pennine basin uk from combined heavy mineral garnet geochemistry and palaeocurrent studies abstract analyses of heavy mineral assemblages garnet geochemistry and palaeocurrent directions may each independently provide useful information on the provenance of sandstones but when such datasets are combined the number of options on the location of possible source areas can be greatly reduced also variations in heavy mineral signatures through a stratigraphical section can be explained in terms of switching between source areas rather than due to unroofing events in a single source area if palaeocurrent directions change at the appropriate levels likewise seemingly random changes in transport direction indicated by palaeocurrent variations through a short stratigraphical section can be shown by the heavy mineral data to be systematic and related to shifts between source areas illustrations of the mutual constraints provided by such combined datasets are drawn from late carboniferous successions of the pennine basin northern england where the contributions of detritus from several distinct source terrains and sediment pathways are well documented hallsworth c r morton a c claoue long j fanning c m 2000 carboniferous sand provenance in the pennine basin uk constraints from heavy mineral and detrital zircon age data sedimentary geology 137 147 185 chisholm j i hallsworth c r 2005 provenance of upper carboniferous sandstones in east derbyshire role of the wales brabant high proceedings of the yorkshire geological society 55 209 233 examples are given of how mineralogically distinct and geographically separated provenances can be identified how variations in heavy mineral suites can be used to identify whether variations in palaeoflow represent variations in provenance and how localised mixing recycling in incised channels can be inferred the final example defines the regional extent of the widespread northerly derived fluvial yeadonian sandstones and provides evidence for the mixing of more local sediment supplies at the basin margins