water balance observations reveal significant subsurface water seepage from lake nam co south central tibetan plateau summary hydrological observations including precipitation runoff evaporation and lake level were performed in detail in the basin of the lake nam co in the southern central tibetan plateau from 2007 to 2011 two runoff coefficients at differing catchment scales were obtained and applied to derive the surface water inflow to the lake from the non glaciated areas total runoff was partitioned into contributions from glaciated and non glaciated areas at two additional catchment scales the runoff from the non glaciated areas amounted to 1400 mm lake depth during the observation period from may 18 to october 17 2008 during which the most complete set of observations was obtained neglecting groundwater contributions this amount accounted for 55 65 of the total water input to the lake nam co the precipitation contribution and the meltwater inflow from the glaciers accounted for 23 28 and 7 22 of the total water input to the lake respectively the water input was found to be 810 1220 mm lake depth 1 63 109 2 47 109 m3 more than the output of the lake during a 5 month period in 2008 similar results were obtained for the years 2007 and 2009 2011 as there is no surface outflow from the lake the large water imbalance can only be explained by water seepage corresponding to an average outflow of 120 190 m3 s 1 or 5 8 mm lake water depth per day it is likely that the main pathway for lake water seepage is through the sub surface fault system which is known to exist in the area

dwindling groundwater resources in northern india from satellite gravity observations 1 northern india and its surroundings home to roughly 600 million people is probably the most heavily irrigated region in the world temporal changes in earth s gravity field in this region as recorded by the grace satellite mission reveal a steady large scale mass loss that we attribute to excessive extraction of groundwater combining the grace data with hydrological models to remove natural variability we conclude the region lost groundwater at a rate of 54 9 km3 yr between april 2002 the start of the grace mission and june 2008 this is probably the largest rate of groundwater loss in any comparable sized region on earth its likely contribution to sea level rise is roughly equivalent to that from melting alaskan glaciers this trend if sustained will lead to a major water crisis in this region when this non renewable resource is exhausted

post processing removal of correlated errors in grace data 1 gravity fields produced by the gravity recovery and climate experiment grace satellite mission require smoothing to reduce the effects of errors present in short wavelength components as the smoothing radius decreases these errors manifest themselves in maps of surface mass variability as long linear features generally oriented north to south i e stripes the presence of stripes implies correlations in the gravity field coefficients here we examine the spectral signature of these correlated errors and present a method to remove them finally we apply the filter to a model of surface mass variability to show that the filter has relatively little degradation of the underlying geophysical signals we seek to recover

gravity and gps measurements reveal mass loss beneath the tibetan plateau geodetic evidence of increasing crustal thickness 1 today some tens of million years after its creation by the collision between india and asia the tibetan plateau is the highest and largest plateau on earth results of geological and tectonic studies indicate that the plateau is extending however almost no quantitative evidence shows whether the plateau is still uplifting or thickening nowadays herein we present geodetic evidence of mass loss beneath the tibetan plateau and increasing crust thickness combined absolute gravity and global positional system gps measurements at three stations in southern and southeastern tibet during two decades reveal uplifting of the tibetan plateau at a millimeter per year level but its underlying mass is diminishing indicating that the crustal thickness is increasing at an annual millimeter to decimeter level

lake volume and groundwater storage variations in tibetan plateau s endorheic basin the tibetan plateau tp the highest and largest plateau in the world with complex and competing cryospheric hydrologic geodynamic processes is particularly sensitive to anthropogenic warming the quantitative water mass budget in the tp is poorly known here we examine annual changes in lake area level and volume during 1970s 2015 we find that a complex pattern of lake volume changes during 1970s 2015 a slight decrease of 2 78 gt yr 1 during 1970s 1995 followed by a rapid increase of 12 53 gt yr 1 during 1996 2010 and then a recent deceleration 1 46 gt yr 1 during 2011 2015 we then estimated the recent water mass budget for the inner tp 2003 2009 including changes in terrestrial water storage lake volume glacier mass snow water equivalent swe soil moisture and permafrost the dominant components of water mass budget namely changes in lake volume 7 72 0 63 gt yr 1 and groundwater storage 5 01 1 59 gt yr 1 increased at similar rates we find that increased net precipitation contributes the majority of water supply 74 for the lake volume increase followed by glacier mass loss 13 and ground ice melt due to permafrost degradation 12 other term such as swe 1 makes a relatively small contribution these results suggest that the hydrologic cycle in the tp has intensified remarkably during recent decades

lake seasonality across the tibetan plateau and their varying relationship with regional mass changes and local hydrology the recent growth and deepening of inland lakes in the tibetan plateau tp may be a salient indicator of the consequences of climate change the seasonal dynamics of these lakes is poorly understood despite this being potentially crucial for disentangling contributions from glacier melt and precipitation which are all sensitive to climate to lake water budget using in situ observations satellite altimetry and gravimetry data we identified two patterns of lake level seasonality in the central northern and northeastern tp lake levels are characterized by considerable increases during warm seasons and decreases during cold seasons which is consistent with regional mass changes related to monsoon precipitation and evaporation in the northwestern tp however lake levels exhibit dramatic increases during both warm and cold seasons which deviate from regional mass changes this appears to be more connected with high spring snowfall and large summer glacier melt the variable lake level response to different drivers indicates heterogeneous sensitivity to climate change between the northwestern tp and other regions

recharge of the upper chalk aquifer at a site in hampshire england 2 solute movement abstract this paper describes a field experiment to study the movement of solutes through the unsaturated zone of the chalk using soil physical techniques to calculate water fluxes and sequential soil coring to measure solute concentrations with depth and time deuterium oxide was used as a tracer to follow water movement nitrate leaching beneath spring barley was calculated below the root zone approximately 40 kg ha 1 yr 1 of nitrate nitrogen were leached beyond root depth 1 m in the two study years at concentrations of between 20 and 75 mg l 1 and at a downward velocity of 0 85 m yr 1

which heterogeneous glacier melting patterns can be robustly observed from space a multi scale assessment in southeastern tibetan plateau abstract region wide investigation of glacier change in high mountain asia marked the strongest recession in southeastern tibetan plateau setp in recent decades however evident differences of quantitative glacier mass balance mb estimations on fine scales exist in the prior reports the large uncertainties in current geodetic observations over this region highlight the need for more independent validations and investigations on the spatial variability of glacier change this study enriched glacier mb estimates over the setp by using the newly released global digital elevation model dem the tandem x and analyzed the spatial pattern of glacier change on multi spatial scales by comparing available satellite based geodetic observations results reveal that the tandem x srtm elevation differences which show no obvious horizontal shifts and no significant elevation dependent bias provide reliable elevation change information over this challenging area on the regional scale the geodetic datasets the aster elevation change rates data tandem x srtm differences icesat achieved a highly consistent estimate of glacier mb at 4 11 1 52 gt a 1 0 60 0 16 m w e a 1 during 2000 and 2010s on the subregional scale the two gridded geodetic datasets revealed a clear contrast between moderate thinning of spring accumulation type glaciers in the south and significantly more negative glacier mb of summer accumulation type glaciers in the north glacier wide mb showed high heterogeneity which was closely related to the combined effect of topographic variation and climate forcings we observed similar glacier thinning rates between debris covered land terminating glaciers and clean ice glaciers 0 50 0 32 m w e a 1 but remarkable more negative mb 0 89 0 36 m w e a 1 of debris covered glaciers connected with glacial lakes which may indicate different evolution process of debris covered glaciers in the monsoon influenced region this study demonstrates that current satellite based geodetic observations achieve overall consistent patterns of glacier mass changes even over the most challenging mountainous areas complicated terrain and climate with the global tandem x dem and increasing observations from the mission we expect improved consistency in glacier mb estimation on large spatial scales as well as detailed investigation of glacier mass change variability in the future

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

the spatial variation of weathering and soil depth across a triassic sandstone outcrop in this study we used an archive of borehole logs from the british geological survey to collect information on the spatial structure of weathering that extends from the surface to competent bedrock across the triassic sherwood sandstone group outcrop 750 km2 in the east midlands uk the borehole logs were used to estimate the thickness of the soil n 280 and soil and saprolite ss the overburden of ice may have increased sub glacial pore water pressure with the fractures and faults acting as a drainage system for the removal of dissolved weathering products

substantial glacier mass loss in the tien shan over the past 50 years long term changes of the mountain glaciers in the tien shan central asia are not well constrained remote sensing data and glaciological models reveal a 27 decline of glacier mass from 1961 to 2012 linked to increased summer melting

review of the status and mass changes of himalayan karakoram glaciers we present a comprehensive review of the status and changes in glacier length since the 1850s area and mass since the 1960s along the himalayan karakoram hk region and their climate change context a quantitative reliability classification of the field based mass balance series is developed glaciological mass balances agree better with remotely sensed balances when we make an objective systematic exclusion of likely flawed mass balance series the himalayan mean glaciological mass budget was similar to the global average until 2000 and likely less negative after 2000 mass wastage in the himalaya resulted in increasing debris cover the growth of glacial lakes and possibly decreasing ice velocities geodetic measurements indicate nearly balanced mass budgets for karakoram glaciers since the 1970s consistent with the unchanged extent of supraglacial debris cover himalayan glaciers seem to be sensitive to precipitation partly through the albedo feedback on the short wave radiation balance melt contributions from hk glaciers should increase until 2050 and then decrease though a wide range of present day area and volume estimates propagates large uncertainties in the future runoff this review reflects an increasing understanding of hk glaciers and highlights the remaining challenges

acceleration of the contribution of the greenland and antarctic ice sheets to sea level rise 1 ice sheet mass balance estimates have improved substantially in recent years using a variety of techniques over different time periods and at various levels of spatial detail considerable disparity remains between these estimates due to the inherent uncertainties of each method the lack of detailed comparison between independent estimates and the effect of temporal modulations in ice sheet surface mass balance here we present a consistent record of mass balance for the greenland and antarctic ice sheets over the past two decades validated by the comparison of two independent techniques over the last 8 years one differencing perimeter loss from net accumulation and one using a dense time series of time variable gravity we find excellent agreement between the two techniques for absolute mass loss and acceleration of mass loss in 2006 the greenland and antarctic ice sheets experienced a combined mass loss of 475 158 gt yr equivalent to 1 3 0 4 mm yr sea level rise notably the acceleration in ice sheet loss over the last 18 years was 21 9 1 gt yr2 for greenland and 14 5 2 gt yr2 for antarctica for a combined total of 36 3 2 gt yr2 this acceleration is 3 times larger than for mountain glaciers and ice caps 12 6 gt yr2 if this trend continues ice sheets will be the dominant contributor to sea level rise in the 21st century

a simple model of variable residence time flow and nutrient transport in the chalk summary a basic problem of modelling flow and transport in chalk catchments arises from the existence of a deep unsaturated zone with complex interactions between flow in fractures and water held in the fine pores of the rock matrix the response of the water table to major infiltration episodes is rapid of the order of days however chemical signals are strongly damped suggesting that this water is of varying age with a corresponding mixed history of nutrient loading clearly this effect should be represented in any model of nutrients in chalk systems the applicability of simplified physically based model formulations to represent the dual response in an integrated way has been investigated by a variety of researchers but it has been shown that these approximations break down in application to the chalk mathias et al mathias s butler a p jackson b m wheater h s this issue characterising flow in the chalk unsaturated zone in wheater h s peach d neal c editors hydrology on locar in the pang lambourn special issue of j hydrol doi 10 1016 j jhydrol 2006 04 010 present a dual permeability model that explains the observed response but such complex formulations are not readily incorporated in catchment scale nutrient models this paper reviews previous approaches to modelling the chalk and then presents a pragmatic approach with transport of solute and water through the unsaturated zone treated separately and combined at the water table varying residence times are included through considering the distance between the water table and the soil surface and the history of nutrient application at the surface if an average rate of downwards migration of the nutrients is assumed it is possible to derive a travel time distribution of nitrate transport to the water table using a dtm digital terrain model map of elevation and information on groundwater levels this distribution can then be implemented through difference equations the rationale behind the model and the resulting algorithm is described and the algorithm then applied to a hypothetical case study of nutrient loading located in the lambourn a groundwater dominated chalk catchment in southern england simulated groundwater concentrations are very similar in magnitude and variability to observed chalk groundwater series suggesting that this simple conceptual model may well be able to capture the dominant responses of nutrient transport through the chalk

time variable ice loss in asian high mountains from satellite gravimetry abstract substantial amount of glacial ice is considered to be melting in the asian high mountains gravimetry by grace satellite during 2003 2009 suggests the average ice loss rate in this region of 47 12 gigaton gt yr 1 equivalent to 0 13 0 04 mm yr 1 sea level rise this is twice as fast as the average rate over 40 years before the studied period and agrees with the global tendency of accelerating glacial loss such ice loss rate varies both in time and space mass loss in himalaya is slightly decelerating while those in northwestern glaciers show clear acceleration uncertainty still remains in the groundwater decline in northern india and proportion of almost isostatic e g tectonic uplift and non isostatic e g glacial isostatic adjustment portions in the current uplift rate of the tibetan plateau if gravity increase associated with ongoing glacial isostatic adjustment partially canceled the negative gravity trend the corrected ice loss rate could reach 61 gt yr 1

three dimensional velocity field of present day crustal motion of the tibetan plateau derived from gps measurements 1 using the measurements of 750 gps stations around the tibetan plateau for over 10 years since 1999 we derived a high resolution 3 d velocity field for the present day crustal movement of the plateau the horizontal velocity field relative to stable eurasia displays in details the crustal movement and tectonic deformation features of the india eurasia continental collision zone with thrust compression lateral extrusion and clockwise rotation the vertical velocity field reveals that the tibetan plateau is continuing to rise as a whole relative to its stable north neighbor however in some subregions uplift is insignificant or even negative the main features of the vertical crustal deformation of the plateau are the following a the himalayan range is still rising at a rate of 2 mm yr the uplift rate is 6 mm yr with respect to the south foot of the himalayan range b the middle eastern plateau has a typical uplift rate between 1 and 2 mm yr and some high mountain ranges in this area like the longmen shan and gongga shan have surprising uplift rates as large as 2 3mm yr c in the middle southern plateau there is a basin and endorheic subregion with a series of ns striking normal faults showing obvious sinking with the rates between 0 and 3 mm yr d the present day rising and sinking subregions generally correspond well to the cenozoic orogenic belts and basins respectively e at the southeastern corner of the plateau there is an apparent trend that the uplift rate is gradually decreasing from between 0 8 and 2 3 mm yr in the inner plateau to between 0 5 and 1 6 mm yr outside the plateau with the decrease of terrain height

time variability of the earth s gravity field hydrological and oceanic effects and their possible detection using grace the grace satellite mission scheduled for launch in 2001 is designed to map out the earth s gravity field to high accuracy every 2 4 weeks over a nominal lifetime of 5 years changes in the gravity field are caused by the redistribution of mass within the earth and on or above its surface grace will thus be able to constrain processes that involve mass redistribution in this paper we use output from hydrological oceanographic and atmospheric models to estimate the variability in the gravity field i e in the geoid due to those sources we develop a method for constructing surface mass estimates from the grace gravity coefficients we show the results of simulations where we use synthetic grace gravity data constructed by combining estimated geophysical signals and simulated grace measurement errors to attempt to recover hydrological and oceanographic signals we show that grace may be able to recover changes in continental water storage and in seafloor pressure at scales of a few hundred kilometers and larger and at timescales of a few weeks and longer with accuracies approaching 2 mm in water thickness over land and 0 1 mbar or better in seafloor pressure

interannual variability of greenland ice losses from satellite gravimetry 1 using extended satellite gravity measurements from the gravity recovery and climate experiment grace here we show that ice losses in southeast greenland appear to have slowed down dramatically since late 2007 while those in the west especially northwest greenland show continued accelerations in recent years over the period april 2002 to november 2009 averaged ice loss rates in eastern greenland 120 31 gt yr are still significantly larger than those in the west 86 3 22 gt yr however the estimated ice loss rate from glaciers in northwest greenland has increased from 30 9 8 gt yr over the first few years 2002 2005 to 128 2 33 gt yr for the more recent period 2007 2009 while the loss rate in southeast greenland for the more recent period has become almost negligible down from 109 28 gt yr of just a few years ago the rapid change in the nature of the regional ice mass in southeast and northwest greenland in the course of only several years further reinforces the idea that the greenland ice sheet mass balance is very vulnerable to regional climate conditions the dramatic slow down of ice loss in southeast greenland observed by grace provides an independent verification of similar reports from other remote sensing data the observed significant interannual variability of greenland ice mass change suggests that it is very challenging to quantify greenland s long term ice mass change rates and some observed apparent accelerations might simply be a reflection of the interannual variability

mineralogy paragenesis and genesis of the braunite deposits of the mary valley manganese belt queensland australia the mary valley manganese deposits exhibit mineralogy and textures characteristic of at least four parageneses the deposits consist mainly of isolated occurrences of braunite together with a number of lower and higher valency manganese oxides and manganese silicates in bedded radiolarian cherts and jaspers of permian age the parageneses are a braunite quartz primary b braunite hausmannite spessartine tephroite quartz metamorphic c hydrated manganese silicates barite braunite hausmannite hydrothermal veins d tetravalent manganese oxides pyrolusite cryptomelane manjiroite nsutite supergene the primary mineralisation is interpreted as the result of the geochemical separation of mn from fe in a submarine exhalative system and the precipitation of mn as oxide within bedded radiolarian oozes and submarine lavas during diagenesis this hydrothermal manganese oxide reacted with silica to produce primary braunite the later geological of evolution of this volcanogenicsedimentary deposit involved metamorphism hydrothermal veining by remobilised manganese and supergene enrichment

four year comparison of water contents beneath a grass ley and a deciduous oak wood overlying triassic sandstone in lowland england summary differences in the seasonal water dynamics of a sand soil overlying triassic sandstone have been investigated to a depth of 9 m beneath both a grass ley and a pendunculate oak woodland within clipstone forest nottinghamshire england fortnightly measurements with a neutron probe over a four year period allowed a comparison of the soil rock water content to depths rarely reported in spring the rate of decrease of water content of the uppermost 2 m of soil was much greater under grass than oak woodland in contrast the rate of decrease under oak was greater after leafing out in may while the rate of rewetting in early autumn was lower for this land use until senescence and leaf fall in late autumn in the uppermost 2 m of soil a depth that includes all plant roots the soil moisture minima were between 47 and 58 mm lower under oak than grass in each year of monitoring as a result of both these drier conditions and the comparatively late leaf fall of this species penetration of the winter season wetting front to 2 m was delayed by between one and three months at the oak site relative to grass in years of near average rainfall rewetting at 9 m lags by 10 12 months compared to the surface giving an average penetration rate for the wetting front to this depth of 25 30 mm day 1 with little observable differences between the land uses preferential flow is evident under both sites affecting the profile to 3 m in all years and to at least 6 m following winters experiencing exceptional rainfall

increasing rates of ice mass loss from the greenland and antarctic ice sheets revealed by grace 1 we use monthly measurements of time variable gravity from the grace gravity recovery and climate experiment satellite gravity mission to determine the ice mass loss for the greenland and antarctic ice sheets during the period between april 2002 and february 2009 we find that during this time period the mass loss of the ice sheets is not a constant but accelerating with time i e that the grace observations are better represented by a quadratic trend than by a linear one implying that the ice sheets contribution to sea level becomes larger with time in greenland the mass loss increased from 137 gt yr in 2002 2003 to 286 gt yr in 2007 2009 i e an acceleration of 30 11 gt yr2 in 2002 2009 in antarctica the mass loss increased from 104 gt yr in 2002 2006 to 246 gt yr in 2006 2009 i e an acceleration of 26 14 gt yr2 in 2002 2009 the observed acceleration in ice sheet mass loss helps reconcile grace ice mass estimates obtained for different time periods

is it possible that a gravity increase of 20 μgal yr 1 in southern tibet comes from a wide range density increase with absolute gravimetric observations from 2010 to 2013 in the southern tibet chen et al 2016 reported a gravity increase of up to 20 gal yr and concluded that it is possible if there was a density increase in a disk range of 580 km in diameter here we used observations from the gravity satellites gravity recovery and climate experiment grace over 12 years to evaluate whether the model was practical because a mass accumulation in such a large spatial range is well within the detectability ability of grace the gravity trend based on their model is orders of magnitude larger than the grace observation thus negating its conclusions we then evaluated contributions from seasonal variation lakes glaciers rivers precipitation and snowfall and concluded that these factors cannot cause such a large gravity signal finally we discussed some possible explanations for the gravity increase of 40 gal in two years

a chemical and isotopic study of the tokaanu waihi geothermal area new zealand abstract the tokaanu waihi geothermal area lies on the northeast flanks of the tongariro volcanic centre an andesitic massif which forms part of the taupo volcanic zone arc subduction system geothermal activity consists of hot springs pools a geyser and an area of steaming ground fumaroles and acidic springs at tokaanu the near neutral ph boiling waters are notable for a high mineral content 3000 mg kg cl relative to other taupo volcanic zone geothermal systems a high b cl ratio and high li alkali ratio the waihi waters and bore waters are lower in mineral content but higher in hco3 so4 mg and ca and represent mixing of deep hot waters with steam heated groundwaters and dilution with cold surface water the sulphate water geothermometer indicates that the deep hot water is at 250 c higher temperatures 350 400 c are indicated for greater depths by the h2s so4 s isotope ratios and the ch4 co2 carbon isotope measurements a minimum residence time of 0 25 ma for co2 and ch4 below the reservoir is proposed but h2s and so4 in the reservoir cannot have coexisted for more than 200 a isotopic analyses of the tokaanu hot spring waters show a significant 180 shift up to 4 from the local meteoric waters some samples show further 180 d and cl enrichment as a result of steam loss at depth and surface evaporation

manganese deposits in turkey distribution types and tectonic setting abstract manganese deposits in turkey are divided into four main groups on the basis of their age host rocks and processes of formation the first is hydrothermal hydrogenetic and rarely diagenetic type manganese deposits which are chiefly associated with radiolarian chert series these deposits occur as lenses and small ore beds within ophiolitic melanges zones of paleo tethyan karakaya and neo tethyan north anatolian and south anatolian suture belts the second is black shale hosted manganese deposits that is found in black shale calcareous shale and calciturbiditic limestone horizons of the passive margin sediments of late cretaceous age in the western taurides these deposits generally are metamorphosed to greenschist facies and include mn carbonate silicate and oxide minerals the third is volcanic arc hosted ores along the black sea margin which occur in different types of metasomatic hydrothermal and stratabound settings rock associations include upper cretaceous dacitic tuff reddish limestone marl and hemipelagic claystone the fourth is oligocene hosted ores in the thrace basin these deposits are similar to those of the paratethyan oligocene belt which occur on the eastern and northern margin of black sea and includes the chiatura georgia nikopol ukraine and varna bulgaria respectively the oligocene mn deposits of the thrace basin were formed by diagenetic replacement processes during a marine regression

estimation of natural groundwater recharge in the karoo aquifers of south africa abstract a 3 year project to study the natural groundwater recharge of aquifers in the semi arid karoo formations of south africa was undertaken two typical karoo aquifers at dewetsdorp and de aar were selected for study purposes data were collected from both the saturated and unsaturated zone neutron probe measurements showed that there was no increase in the water content beneath a depth of 1m below the surface even with the exceptionally high rainfall in february 1988 neutron measurements indicated that very little soil matrix flow occurred which implied that most of the recharge occurred along preferred pathways a triangular finite element network was used to determine the relative saturated volume fluctuations svf of the aquifers from the observed water level changes over a period of time which allowed determination of the storativity s and the recharge the main advantage of the method lies in determining recharge and storativity which are both unknowns in the water balance equation and which both contribute to the water level response the svf method showed that the recharge in the karoo formations of south africa varies between 2 and 5 of the annual rainfall in areas which are overlain by a thick soil cover the recharge is less than 3 while recharge in hilly areas with a thin soil cover may be of the order of 5

glaciology no ice lost in the karakoram the fate of glaciers in the greater himalaya is widely discussed but poorly known a new measurement in the central karakoram mountain range suggests that glacier mass change in this region contributes to sea level rise nearly 0 05 mm per year less than has been thought

siliceous sublacustrine spring deposits around hydrothermal vents in lake taupo new zealand chimneys around hydrothermal vents at a depth of c 140 m in the horomatangi reefs area in lake taupo new zealand are composed of amorphous silica opal a with lesser amounts of mn fe and hg rich precipitates detrital quartz and feldspar grains are found in the surrounding sediments the associated biota includes fish bacteria sponges crayfish amphipods copepods ostracodes annelids and other unidentified organisms much of this biota however is not preserved in the opal a deposits instead the silicified biota includes filamentous microbes and diatoms scattered coccoid microbes fungal hyphae and spores rare sponge spicules and rare worm tubes the diatoms coccoid microbes and fungi were brought into the area with the detrital sediment in ancient successions distinction between sublacustrine terrestrial and some marine hot spring deposits may be difficult because the precipitates share many similarities distinction based on the biota is viable only if palaeoecological information can be inferred from accurately identified organisms unfortunately silicification commonly disguises microbes and precludes their accurate identification diagenetic transformation of opal a to its more stable polymorphs also destroys many original depositional fabrics and silicified microbes distinction between the different types of spring deposit may therefore depend on the interpretation of their overall sedimentological and stratigraphic setting

spatial heterogeneity of high resolution chalk groundwater geochemistry underground quarry at saint martin le noeud france chalk groundwater is an important aquifer resource in france because it accounts for a production of 12 million m3 y 1 with a large proportion reserved for drinking water processes occurring in the unsaturated zone uz and the overlying superficial formations have a high impact on chalk groundwater geochemistry and require better understanding the study site is a former underground chalk quarry located near beauvais france that extends over 1200 m in length at a depth ranging from 20 to 30 m the water table intersects the cavity creating 15 underground lake that give access to the chalk groundwater lakes geochemistry has been studied water samples were collected in july 2013 and major ion concentrations were analyzed uz and clay with flints thickness above each lake were estimated qualitatively using an electromagnetic sensor em31 and underground gps the results unexpectedly showed that groundwater quality varied widely in spatial terms for both allochthonous and autochthonous ions e g hco3 ranged from 2 03 to 4 43 meq l 1 no3 ranged from 0 21 to 1 33 meq l 1 principal component analysis indicated the impact of agricultural land use on water quality with the intake of no3 as well as so42 cl and ca2 chalk groundwater geochemistry is compared with the nature and structure of the uz we highlight correlations 1 between thick clay with flints layers and the ions mg2 and k and 2 between uz thickness and na in conclusion this paper identifies various ion sources agriculture clay with flints and chalk and demonstrates different processes in the uz dissolution ionic exchange and solute storage

advances in modelling groundwater behaviour in chalk catchments groundwater in chalk catchments is a major resource that also helps support internationally important habitats and ecosystems its dual porosity and dual permeability properties coupled with large scale structural features such as hard rock layers and marls produce a highly complex hydrogeological system recent impacts from groundwater flooding as well as vulnerability to drought have raised questions over the ability of traditional approaches to model these aquifers current work on near surface hydrological processes has highlighted the importance of the soil and weathered zone for controlling recharge rates in addition karst like features sedimentary deposits and valley bottom processes govern stream aquifer interaction and present a challenge in their representation in any modelling system methods that have and are being developed to incorporate these features and their use in modelling chalk catchments are described these are required in order to address major challenges such as groundwater flooding and drought impacts both of which could become more frequent and intense as a result of climate change

breccia hosted manganese rich minerals of alpi apuane italy a marine redox generated deposit mn rich beds occur within the brecce di seravezza formation bsfm intercalated between norian metadolostone megalodontic marble and hettangian marble in the alpi apuane italy the bsfm is a rockfall talus deposit that accumulates at the base of the footwall scarp of normal faults bordering extensional marine coastal basins the type sequence of metabreccia ends with a bed of chloritoid schist interpreted as the metamorphic equivalent of lateritic soils the four main types of mn mineral assemblages are 1 braunite piemontite and rare hausmannite 2 piemontite braunite hollandite and minor rhodochrosite and kutnahorite 3 braunite hollandite and rare piemontite the other minerals are quartz calcite muscovite phlogopite baryte and minor hematite rutile and apatite during the alpine orogeny pressures of 4 6 kb and temperatures of 350 380 c were attained mn assemblages with hematite and phlogopite indicate o2 10 8 for t 350 c and o2 10 6 when braunite appears on the mn rich rocks ti fe nb sn ta hf th ga rb pr k na nd were identified as detrital in origin and are positively correlated with al u is positively correlated with co pb bi mo the rare earth element patterns normalized to seawater show a negative slope towards the heavy rare earth elements with positive ce anomalies in some samples positive ce and eu anomalies in other samples and negative ce and positive eu anomalies in a third group the eu concentrations are nearly constant and the eu anomalies reflect differences in the concentration of other rare earth elements for ce a positive correlation with al2o3 sio2 indicate that a detrital signature prevails on that produced by duration of seawater exposure but a significant good correlation of la tm lu with mg could indicate at least for these elements a seawater signature only in some samples ba eu sr show anomalously high concentrations likely of hydrothermal origin however generally in all the chemical variation diagrams the bsfm samples fall outside the field of hydrothermal and hydrogenous deposits as defined in the literature for other mn deposits in addition metabasites and metavolcaniclastic beds are absent from the bsfm sequence and bsfm coastal basins were for the most part separated from the open ocean and related streams that must be excluded as possible mn sources owing to the arid climate of late triassic the runoff was negligible and the groundwater oxidizing and alkaline were unable to mobilize mn the bsfm basins are then the most suitable depositional environment for mn the water column was stagnant and stratified only where bottom of the basin was deeper than the oxic anoxic boundary reducing marine bottom waters percolated within the fractured basement and leached mn from disseminated minerals of metamorphic rocks and then rising along fault and fractures supplied mn to the bottom waters afterwards when tectonic uplift and sealevel drop brought the bottom into the oxic field mn precipitated and formed the mn rich matrix of the bsfm deposits

estimation of groundwater recharge to chalk and sandstone aquifers using simple soil models abstract on the assumption that the water draining below the root zone is potentially available for groundwater recharge two current uk methods for estimating annual groundwater recharge have been compared with a new soil model using data from four sites under permanent grass in the uk two sites representative of the chalk aquifer at bridgest farm hampshire and fleam dyke cambridgeshire and two sites on the triassic sandstone at bicton college devon and bacon hall shropshire a four root layers model frlm the penman grindley model and the uk meteorological office rainfall and evaporation calculation system morecs were used the new soil model was run with potential evaporation as input both from the morecs and from the penman monteith equation the models were run for the chalk sites both with and without a bypass flow of 15 of rainfall bypass was not considered for the sandstone sites the performance of the models was tested against neutron probes measurements of soil moisture deficits in addition the annual groundwater recharge estimated from the models was compared with the published values obtained from the zero flux plane method generally the penman grindley model was more successful in predicting the time for soil to return to its field capacity than in predicting the magnitude of the soil moisture deficit the annual groundwater recharge was predicted with reasonable accuracy the morecs relatively tended to overestimate the soil moisture deficits and to delay the time at which the soil returns to its field capacity the consequences were underestimates of annual groundwater recharge owing either to the higher values of potential evaporation calculated from the morecs or tothe high available water capacity values associated with the soils under consideration the new soil model frlm predicts the soil moisture deficits successfully and hence is reliable in estimating the annual groundwater recharge the model is capable of doing this with potential evaporation input calculated either from the morecs or from the penman monteith equation the model also demonstrated that the inclusion of 15 of rainfall as bypass flow is viable for chalk sites

a spatially resolved estimate of high mountain asia glacier mass balances from 2000 to 2016 glacier mass balances in high mountain asia are uncertain satellite stereo imagery allows a spatially resolved estimate for about 92 of the glacierized area and yields a region wide average of about 16 gt yr 1 for 2000 to 2016

mechanisms of groundwater recharge and pesticide penetration to a chalk aquifer in southern england abstract in order to assess the potential for enhanced agrochemical contamination of shallow groundwaters a field study was established on the upper chalk in hampshire uk two instrumented sites 380 m apart were established on a hillslope one on the interfluve with a deep water table 18 m depth the other on the dry valley bottom where the groundwater was close to the surface 4 m depth hourly measurements of water potentials in the unsaturated zone to 3 0 m depth identified very different groundwater recharge processes between the two sites in response to the same storm event on the interfluve site with the deep water table only matrix flow through the chalk unsaturated zone at 3 m depth was identified in contrast at the dry valley bottom with a shallow water table both rapid preferential flow and matrix flow processes were observed at a 3 m depth the correlation between groundwater depth measurements and unsaturated profile moisture content measurements demonstrated the importance of the capillary fringe in sustaining a higher moisture content in the unsaturated zone at the shallow groundwater site the resulting reduced water storage capacity for vertical drainage fluxes meant that little water was required to wet the shallow profile before rapid preferential flow events demonstrated by rapid water potential responses occurred however where the groundwater was deeper intermediate storage sites located on chalk surfaces and at chalk ped block contact points remained empty and unsaturated water potential profiles showed that rainfall pulses were attenuated as these sites absorbed the downward water fluxes consequently preferential events at these deep groundwater sites are rare the importance of these intermediate storage sites in controlling recharge processes is highlighted the potential mass load of pesticide transported to the shallow groundwater in preferential events during 1996 7 was determined using bromide tracer studies water balance calculations and measured groundwater pesticide concentrations an estimated 0 1 of the applied pesticide reached the shallow groundwater along preferential pathways in 1996 7 calculations under a worst case scenario showed that this value did not increase beyond 0 2 of pesticide applied

correction to revisiting the earth s sea level and energy budgets from 1961 to 2008 geophysical research letters vol 40 4066 doi 10 1002 grl 50752 2013 correction to revisiting the earth s sea level and energy budgets from 1961 to 2008 john a church neil j white leonard f konikow catia m domingues j graham cogley eric rignot jonathan m gregory michiel r van den broeke andrew j monaghan and isabella velicogna received 5 july 2013 accepted 12 july 2013 published 8 august 2013 citation church j a n j white l f konikow c m domingues j graham cogley e rignot j m gregory m r van den broeke a j monaghan and i velicogna 2013 correction to revisiting the earth s sea level and energy budgets from 1961 to 2008 geophys res lett 40 4066 doi 10 1002 grl 50752 1 in the paper revisiting the earth s sea level and energy budgets from 1961 to 2008 by john a church et al geophysical research letters 38 l18601 doi 10 1029 2011gl048794 2011 the 0 700 m thermosteric sea level and ocean heat content time series updated from domingues et al 2008 did not re ect global estimates because the contribution from the south indian ocean was accidentally omitted this error does not lead to visible differences in figure 2a or table 1 and only contributes to a minimal difference in figure 3 however it does affect the shallow ocean larger by 22 24 the total ocean larger by 13 14 the total storage larger by 12 13 and the total forcing minus total storage reduced by 3 terms in table 2 the corrected table 2 is reproduced below the overall conclusions are also not affected by the above error the corrected time series version 2 0 used herein are available at http www cmar csiro au sealevel thermal expansion ocean heat timeseries html reference domingues c m j a church n j white p j gleckler s e wijffels p m barker and j r dunn 2008 improved estimates of upper ocean warming and multi decadal sea level rise nature 453 7198 1090 1093 doi 10 1038 nature07080 table 2 the earth s heat budget a component shallow ocean 0 700 m deep ocean 700 3000 m abyssal ocean 3000 m bottom total ocean storage glaciers latent only antarctica latent only greenland latent only sea ice continents atmosphere total other storage total storage 217 5 b solar ozone well mixed ghgs energy consumption volcanic outgoing radiation total forcing total forcing a total storage a the integrated changes in the heat storage and the radiative forcing are in units of 10 j the total forcing minus the total storage is the amount of energy that must be balanced by the aerosol cooling or other climate forcing b bold numbers indicate sum of other rows as indicated in rst column 2013 american geophysical union all rights reserved 0094 8276 13 10 1002 grl 50752

a reconciled estimate of glacier contributions to sea level rise 2003 to 2009 glaciers distinct from the greenland and antarctic ice sheets are losing large amounts of water to the world s oceans however estimates of their contribution to sea level rise disagree we provide a consensus estimate by standardizing existing and creating new mass budget estimates from satellite gravimetry and altimetry and from local glaciological records in many regions local measurements are more negative than satellite based estimates all regions lost mass during 2003 2009 with the largest losses from arctic canada alaska coastal greenland the southern andes and high mountain asia but there was little loss from glaciers in antarctica over this period the global mass budget was 259 28 gigatons per year equivalent to the combined loss from both ice sheets and accounting for 29 13 of the observed sea level rise

modelling flow and heat transfer through unsaturated chalk validation with experimental data from the ground surface to the aquifer abstract during the winter and spring of 2000 2001 large floods occurred in northern france somme river basin and southern england patcham area of brighton in valleys that are developed on chalk outcrops the floods durations were particularly long more than 3 months in the somme basin and caused significant damage in both countries to improve the understanding of groundwater flooding in chalk catchments an experimental site was set up in the hallue basin which is located in the somme river basin france unsaturated fractured chalk formation overlying the chalk aquifer was monitored to understand its reaction to long and heavy rainfall events when it reaches a near saturation state the water content and soil temperature were monitored to a depth of 8 m and the matrix pressure was monitored down to the water table 26 5 m below ground level the monitoring extended over a 2 5 year period 2006 2008 under natural conditions and during two periods when heavy artificial infiltration was induced the objective of the paper is to describe a vertical numerical flow model based on richards equation using these data that was developed to simulate infiltrating rainwater flow from the ground surface to the saturated aquifer the marthe computer code which models the unsaturated saturated continuum was adapted to reproduce the monitored high saturation periods composite constitutive functions hydraulic conductivity saturation and pressure saturation that integrate the increase in hydraulic conductivity near saturation and extra available porosity resulting from fractures were introduced into the code using these composite constitutive functions the model was able to accurately simulate the water contents and pressures at all depths over the entire monitored period including the infiltration tests the soil temperature was also accurately simulated at all depths except during the infiltrations tests which contributes to the model validation the model was used to calculate the aquifer recharge over a long period that included droughts and floods the calculated recharge is realistic as it makes it possible to simulate the corresponding monitored groundwater level data which increases confidence in the modelling approach

genetic diversity of manganese deposition in the terrestrial geological record terrestrial manganese deposits formed by hydrothermal sedimentary and supergene processes ancient analogues of modern oceanic hydrothermal deposits formed in spreading centre and subduction related settings and those deposited from terrestrial hot springs are discussed sedimentary mn oxide deposits formed in shallow water at the margins of stratified oceans above the redoxcline during sea level changes mn carbonate deposits probably formed by diagenesis through mn oxyhydroxide reduction coupled with organic matter oxidation climatic variation and basin water stratification responsible for mn concentration were manifestations of atmospheric coz content prompted by tectonism supergene manganese enrichment in continental weathering profiles was mainly dictated by climate topography and drainage systems manganese deposits of diverse genetic types occur in the terrestrial geological record roy 1981 these were produced by direct hydro thermal activity sedimentary processes and continental weathering although the processes may be interrelated each involves distinct mechanisms that place the deposits into specific genetic types some of these processes are best understood in preset day depositional sites the ancient environments were determined by the intensity and style of tectonism volcanism and hydrothermal activity the composition of the atmosphere and the hydrosphere and the development of the biosphere which all varied with time it is my intention to unfold the total panorama of the environmental evolution during different time envelopes that produced a variety of manganese deposits in the past only major deposits and those providing distinctive evidence of their environment of deposition will be considered here

analysis of water level response to rainfall and implications for recharge pathways in the chalk aquifer se england summary water table response to rainfall was investigated at six sites in the upper middle and lower chalk of southern england daily time series of rainfall and borehole water level were cross correlated to investigate seasonal variations in groundwater level response times based on periods of 3 month duration the time lags in days yielding significant correlations were compared with the average unsaturated zone thickness during each 3 month period in general for cases when the unsaturated zone was greater than 18 m thick the time lag for a significant water level response increased rapidly once the depth to the water table exceeded a critical value which varied from site to site for shallower water tables a linear relationship between the depth to the water table and the water level response time was evident the observed variations in response time can only be partially accounted for using a diffusive model for propagation through the unsaturated matrix suggesting that some fissure flow was occurring the majority of rapid responses were observed during the winter spring recharge period when the unsaturated zone is thinnest and the unsaturated zone moisture content is highest and were more likely to occur when the rainfall intensity exceeded 5 mm day at some sites a very rapid response within 24 h of rainfall was observed in addition to the longer term responses even when the unsaturated zone was up to 64 m thick this response was generally associated with the autumn period the results of the cross correlation analysis provide statistical support for the presence of fissure flow and for the contribution of multiple pathways through the unsaturated zone to groundwater recharge

recharge of the upper chalk aquifer at a site in hampshire england 1 water balance and unsaturated flow abstract measurements of the annual cycle of changes in water content and potential in the 40 m thick unsaturated zone of upper chalk at a site in southern england are described measured evaporation continued at the penman potential rate until the soil moisture deficit reached 175 mm this suggested that a root constant of 200 mm would be more appropriate than the much lower values generally used the field capacity concept could not be reconciled with the timing of renewed water recharge and the reasons for this are discussed the mechanisms of water flow through the unsaturated zone of the chalk are examined and it is shown that at this upper chalk site matrix flow is the dominant recharge mechanism

evaluation of glacier changes in high mountain asia based on 10 year grace rl05 models in this paper 10 years of time variable gravity data from the gravity recovery and climate experiment release 05 have been used to evaluate the glacier melting rate in high mountain asia hma using a new computing scheme i e the space domain inverse method we find that in hma area there are three different kinds of signal sources that should be treated together the two generally accepted sources glacier melting and india underground water depletion are estimated to change at the rate of 35 0 5 8 gt yr 0 09 mm yr sea level rising and 30 6 5 0 gt yr respectively the third source is the remarkable positive signal 30 gt yr in the inner tibetan plateau which is challenging to explain further we have found that there is a 5 year undulation in pamir and karakoram which can explain the controversies of the previous studies on the glacier melting rate here this 5 year signal can be explained by the influence of arctic oscillation and el nino southern oscillation

variations in the earth s oblateness during the past 28 years 1 analysis of satellite laser ranging slr data indicates that the earth s dynamic oblateness j2 has undergone significant variations during the past 28 years the dominant signatures in the observed variations in j2 are 1 a secular decrease with a rate of approximately 2 75 10 11 yr 1 2 seasonal annual variations with a mean amplitude of 2 9 10 10 3 significant interannual variations with timescales of 4 6 years and 4 a variation with period of 21 years and an amplitude of 1 4 10 10 with minimum in december 1988 two large interannual variations are related to the strong el nino southern oscillation events during the periods of 1986 1991 and 1996 2002 and it appears that another interannual cycle may have started in late 2002 the superposition of the decadal variation on the interannual signal makes the j2 fluctuation appear to be anomalously large during the 1996 2002 period contemporary models of the mass redistributions in the atmosphere ocean and surface water can explain a major part of the 4 to 6 year fluctuations however the cause of the decadal variation remains unknown

tibet uplift and erosion abstract the 5 km high tibetan plateau is an outstanding topographic feature on the earth today its horziontal extent elevation and location cause significant effects on modern atmospheric circulation and climate so the history of uplift of the surface of tibet is linked to cenozoic climate changes at local regional and perhaps global scales geological and geophysical studies of the plateau are contributing data on the present and past deformation of the tibetan lithosphere that has formed the plateau primarily during the cenozoic the principal of isostasy then can be used to estimate the elevation history of the surface for a given deformation history different parts of tibet probably had different uplift histories but presently available data are not sufficient for distinguishing many contrasts in one scenario cretaceous and early cenozoic north south distributed shortening of tibetan crust and mantle lithosphere probably caused significant uplift of the surface relative to sea level to perhaps half of the present elevation by the early miocene thinning of the high density mantle portion of the lithosphere during the miocene may then have allowed the thick tibetan crust to rise close to its present elevation perhaps higher before 8 ma since then slow east west extension of tibet probably reduced the crustal thickness slightly and may have caused the elevation of the plateau to decrease during the late cenozoic erosion of tibet unlike narrow mountain belts has been unable to match the uplift of a broad plateau orographic precipitation and efficient river networks concentrate erosion on the edges while the interior is protected from significant erosion despite its lofty elevation the southern edge of the plateau the himalaya has suffered a minimum of 25 km of denudation since the miocene while central tibet shows little or no sign of major erosion since that time the gangdese arc in southern tibet was rapidly eroded during the mid miocene when 4 km of rock apparently were removed from the surface as shown by mineral cooling ages this pulse of erosion was probably caused by a combination of local thrust system movement and changes in base level and precipitation due to relative elevation changes between the gangdese and the himalaya to the south the modern long wavelength flatness of tibet is unlikely to have been caused by erosion and indicates viscous flow at some level of the lithosphere has been acting to level the plateau surface

grace observes small scale mass loss in greenland using satellite gravity data between february 2003 and january 2008 we examine changes in greenland s mass distribution on a regional scale during this period greenland lost mass at a mean rate of 179 25 gt yr equivalent to a global mean sea level change of 0 5 0 1 mm yr rates increase over time suggesting an acceleration of the mass loss driven by mass loss during summer the largest mass losses occurred along the southeastern and northwestern coast in the summers of 2005 and 2007 when the ice sheet lost 279 gt and 328 gt of ice respectively within 2 months in 2007 a strong mass loss is observed during summer at elevations above 2000 m for the first time since the start of the observations

genesis of stromatactis cavities between submarine crusts in palaeozoic carbonate mud buildups it is concluded that the sedimentary structure stromatactis is a calcite cement fill of a swarm of labyrinthine cavities developed in marine carbonate muds of palaeozoic bioherms commonly with geopetal sediment field and petrographic evidence is examined from the ordovician of dalarna sweden the devonian of the canning basin australia and of belgium and the carboniferous of lancashire u k in all four occurrences the host microspar encloses masses of radiaxial fibrous calcite with sub horizontal floors following other workers radiaxial fibrous calcite is regarded as an altered marine cement a conclusion supported by the presence of overlying geopetal sediments with marine fossils widespread evidence of early submarine cementation in palaeozoic mud mounds isotopic analyses and the presence of microdolomites the stromatactis masses are separated from each other by laminae of host biomicrospar which show discontinuities resembling fractures which are healed with the early marine cement or filled with marine internal sediments the fractures are therefore of submarine origin the evidence points to episodic submarine lithification of the carbonate muds yielding successive crusts between which cavities were eroded and then filled the crusts were broken and rotated during bioturbation differential compaction or shearing during burial

the significance of flow in the matrix of the chalk unsaturated zone the significance of flow in the matrix of the chalk unsaturated zone in comparison with flow in fractures has been the subject of much debate in this article important elements of the literature are discussed in detail and several simple modelling analyses based on steady state flow are presented a study of the sensitivity of solute spreading to fracture spacing in models that ignore matrix flow shows that this latter assumption is generally incompatible with observed solute profiles unless unrealistically small fracture spacings are assumed the effect of air phase continuities e g bedding planes on matrix flow has also been examined these discontinuities are frequently interrupted by points of connectivity between matrix blocks an issue therefore is the relationship between connectivity and its effect on inter block conductance a simple analysis of the laplace equation shows that just 1 connectivity represents an effective pathway equivalent to 18 of the local rock hydraulic conductivity obviously when there is no fracture flow solute spreading is significantly reduced however dual permeability model simulations show that matrix flow reduces solute spreading in the presence of persistent fracture flow all of the above studies suggest that flow in the matrix of the chalk unsaturated zone is significant and that ignoring it may result in a serious misunderstanding of the system

how fast is the middle lower crust flowing in eastern tibet a constraint from geodetic observations various geophysical observations including seismological and magnetotelluric imaging have implied that the deep crust beneath eastern tibet may be partially melted and flowing faster than the brittle upper crust however it is still unclear how much faster the deep crust is flowing geodetic observations which are more sensitive to dynamic changes provide constraints on the flow rate of the middle and lower crust mlc three dimensional gps velocities show that deformation within the brittle upper crust contributes little 0 02 0 02 mm yr to the overall surface uplift 2 7 0 3 mm yr therefore two plausible models for the surface uplift are discussed which are consistent with the geodetic constraints in the deep crustal flow model crustal thickening requires the horizontal flow rate of the mlc to be 330 710 of the rate of motion of the upper crust and the deepening of the moho is only up to 35 of that required to maintain isostatic balance isostasy may not be maintained over the geodetic timescale in the hybrid model of deep crustal flow and convective lithospheric detachment the moho is uprising and only weak or moderate 130 250 deep crustal flow is required which results in moderate present day crustal thickening beneath eastern tibet this result improves our understanding of the plateau construction and dynamics and also offers advice for numerical simulations

estimating infiltration recharge using a response function model abstract rainfall infiltration influences both the quantity and quality of groundwater systems the knowledge of the process of infiltration recharge is of great importance to the management of groundwater systems and the hydraulically connected streams in this study a response function model is developed to estimate soil water flux at the water table or the process of infiltration recharge from rainfall and evaporation data the gamma probability density function is modified to represent the travel time distribution of infiltrating water by rainfall events the travel time distribution is used to determine the recharge process according to the effective infiltration of a rainfall event the effective infiltration is the amount of soil water pushed down into groundwater by infiltrating water of a rainfall event and is evaluated based on the vadose zone soil water balance superposition is employed to compute the recharge rate produced by a sequence of rainfall events estimations of soil water flux at different groundwater depths are compared with lysimetric observations in the field good agreements between the estimated and observed results confirm the reliability of the response function model for predicting infiltration recharge processes

mechanisms of water storage and flow in the unsaturated zone of the chalk aquifer abstract it is known that the volumes of water draining from some chalk catchments in recessions are significantly greater than can be explained by gravity drainage from fissure porosity the most likely source of this water is slow drainage from the matric porosity above the water table this paper suggests that the location of this storage is in the irregularities on the fissure surfaces studies of resin impregnated blocks of chalk failed to reveal the presence of hydrologically significant microfissures or macropores that could be the source of additional drainage ultrasonic measurements at varying values of effective stress show no indication of changes in the acoustic transmission properties that could be attributed to closure of microfissures drainage and mercury intrusion measurements indicate that there is significant storage on block surfaces the drainage measurements confirm that the storage is of the order of magnitude about 0 3 needed to explain the slow drainage this additional storage explains why the water table is slow to respond after recharge events and why the chalk is resilient to drought the presence of storage in the unsaturated zone implies that the position of the water table may not be an accurate indicator of groundwater resources the concept of filling and draining of irregularities on fissure surfaces also leads to a new model for the generation of fissure flow in the unsaturated zone of the chalk this suggests that fissure flow can be generated at any depth in the profile and in a sequence of uniform vertical permeability is likely to originate near the water table rather than high in the unsaturated zone

opaline cherts associated with sublacustrine hydrothermal springs at lake bogoria kenya rift valley an unusual group of cherts found at saline alkaline lake bogoria in the kenya rift differs from the magadi type cherts commonly associated with saline alkaline lakes the cherts are opaline rich in diatoms and formed from a siliceous probably gelatinous precursor that precipitated around submerged alkaline hot springs during a holocene phase of high lake level silica precipitation resulted from rapid drop in the temperature of the spring waters and possibly ph lithification began before subaerial exposure ancient analogous cherts are likely to be localized deposits along fault lines

analysis of rainfall recharge relationships abstract understanding the recharge process and its relationship with rainfall is of critical importance to the management of groundwater systems and enormous effort has been made to estimate the amount and process of recharge by infiltration using precipitation data in the present research in situ lysimeter experiments and numerical simulations were used to study the relationships between rainfall and recharge by infiltration at different groundwater depths four lysimeters 1 5 3 4 5 and 5 m deep were installed in the field to measure the infiltration recharge rates under conditions of fixed water tables at the bottoms of the soil columns annual infiltration recharges at different groundwater depths were obtained through the lysimeter measurements the effect of rainfall pattern and annual rainfall distribution on infiltration recharge was simulated at various groundwater depths using a numerical model based on soil water dynamics and comparisons of the simulated and observed recharges showed very good agreement relationships between rainfall and infiltration recharge at different groundwater depths were investigated using the lysimeter measurements and computer simulations groundwater systems were classified into three categories i e shallow water table intermediate water table and deep water table based on the relationship between rainfall and infiltration recharge at different groundwater depths

self potential as a predictor of seawater intrusion in coastal groundwater boreholes abstract monitoring of self potentials sps in the chalk of england has shown that a consistent electrical potential gradient exists within a coastal groundwater borehole previously affected by seawater intrusion si and that this gradient is absent in boreholes further inland furthermore a small but characteristic reduction in this gradient was observed several days prior to si occurring we present results from a combined hydrodynamic and electrodynamic model which matches the observed phenomena for the first time and sheds light on the source mechanisms for the spatial and temporal distribution of sp the model predictions are highly sensitive to the relative contribution of electrochemical exclusion and diffusion potentials the exclusion efficiency in different rock strata geoelectric heterogeneity largely due to marls and hardgrounds with a relatively high exclusion efficiency was the key factor in controlling the magnitude of the modeled sp gradient ahead of the saline front and its evolution prior to breakthrough the model results suggest that where sufficient geoelectric heterogeneity exists borehole sp may be used as an early warning mechanism for si

anomalous precipitation signatures of the arctic oscillation in the time variable gravity field by grace summary the arctic oscillation ao controls winter climates in the northern hemisphere to a large extent positive ao brings lower higher surface temperature and higher lower precipitation in high middle latitude regions and negative ao reverses the situation in this study we investigate signals of anomalous precipitations caused by ao using the data of the gravity recovery and climate experiment grace satellites wintertime mass deviations inferred from grace in the high and middle boundary 55n latitude regions in eurasia showed highly positive and negative correlations with the ao indices this possibly reflects the northward and southward shift of the centre of winter precipitation during the positive and negative phases of ao respectively wintertime mass deviations also showed positive and negative correlations with the ao indices in the northern and southern parts of greenland respectively but the boundary was further to the north say 75n ao redistributes the water mass as much as 1000 gt between high and middle latitude regions in the northern hemisphere such mass redistribution causes significant surface deformation by loading large enough to be observed by global positioning system this also causes the shift of the earth s rotation axis especially towards the greenwich meridian large enough to be detected with space geodetic techniques ao signatures are also derived from the empirical orthogonal function eof analysis as the first leading mode of grace data after excluding seasonal linear and quadratic components the eof analysis also demonstrates that though ao is a main contributor to bring anomalous winter precipitation in the northern hemisphere as a whole in north america however influence of the el nino and southern oscillation on the winter precipitation anomaly is larger than ao

evidence for a shallow highly permeable zone in the chalk of hampshire u k abstract studies of the chalk in the u k in the last 10 15 years have shown that it is generally the top 20 50 m below the water table which provides most of the aquifer yield an investigation in hampshire in connection with a river augmentation scheme using seasonal groundwater abstraction shows the chalk in the area to have a particularly thin and well developed 6 m thick zone possessing both high transmissivity and storativity evidence is put forward to support its existence

large scale seasonal changes in glacier thickness across high mountain asia recently increased efforts have been made to estimate the mass budgets of glaciers in high mountain asia hma however seasonal changes in glaciers are poorly understood despite the fact that seasonal meltwater released from glaciers is a crucial local water resource in hma utilizing satellite altimetry and gravimetry data we constructed annual changes in glacier elevation and identified two general patterns of the seasonality of glacier elevation changes glaciers in the periphery of hma except for those in the eastern himalayas thicken from approximately december to april june thus exhibiting winter and spring accumulation glaciers in the inner tibetan plateau especially those in western kunlun and tanggula accumulate from approximately march to approximately august thus exhibiting spring and summer accumulation the amounts of seasonal glacier ablation were obtained using a new approach of direct observations of glacier changes rather than inferring changes using a climate model

unsaturated flow and solute transport through the chalk tracer test and dual permeability modelling a tracer test was carried out in the unsaturated chalk at the fleam dyke research site in cambridgeshire uk to investigate the role of the chalk fractures and matrix in unsaturated flow and solute transport the experiment under natural rainfall conditions involved distributing deuterated water on a grass covered lysimeter a cube of volume 125 m3 and on an adjacent 4 m 4 m field plot tracer migration was monitored through regular core sampling and collection of lysimeter drainage water the presence of occasional secondary peaks in sampling of the vertical tracer profile suggested the occurrence of fracture flow allowing some tracer to bypass the chalk matrix however in the 15 months following application none of the tracer was detected in the lysimeter drainage at 5 m depth modelling of the tracer results was undertaken with the 1 d numerical transient dual permeability model macro 5 0 initially developed for macroporous soils modelling results showed that macro 5 0 could reliably simulate transient recharge through the chalk the simulations suggested that fracture flow is important at the site but that it is only initiated at 1 m depth or deeper the extent of fracture flow appeared to be highly variable in different layers of the profile varying between 40 and 85 of the cumulative flux mainly depending on the saturated hydraulic conductivity of the matrix diffusion between the fractures and the matrix tended to equalize solute concentrations in both flow domains although solute bypass through the fractures occurred in some chalk strata besides diffusive exchange the modelling stressed the importance of advective exchange of solutes the results suggest that the chalk aquifer at the fleam dyke site is only moderately vulnerable to pollution even though for moderate rainfall conditions some bypass flow was possible

transient simulations of flow and transport in the chalk unsaturated zone chalk is a fractured porous medium composed of matrix blocks bounded by interconnected fractures furthermore there are a number of commonly observed and apparently contradictory phenomena these include a fast water table response slow solute migration and very little solute dispersion to the authors knowledge no unified physically based numerical model has been able to reconcile all of these points in this paper these issues were addressed through the development of a transient dual permeability model of flow and transport the behaviour of the model was explored through a hypothetical scenario the one dimensional model featured a fixed water table at 10 m depth a recharge time series derived using the penman grindley model in conjunction with daily precipitation and monthly potential evaporation data from the kennet valley berkshire was applied at the top of the model a conservative solute that could be tritium chloride or nitrate was applied to the recharge for 1 year subsequent years involved the input of clean water the simulations suggested that although transient effects have been previously neglected overlying soil and gravelly chalk layers are likely to cause significant attenuating effects on flow such that most flow occurs through the matrix fracture flow was found to be episodic and infrequent and represented between 17 and 30 of the annual recharge

slight mass gain of karakoram glaciers in the early twenty first century the mass balance of hindu kush karakoram himalaya glaciers has been debated partly because of a severe lack of observations from the region an analysis of the regional mass balance of karakoram glaciers by comparison of digital elevation models from 1999 to 2008 reveals a small glacier mass gain in the area

precipitation driven glacier changes in the pamir and hindu kush mountains glaciers in the pamir hindu kush karakoram appear to be less influenced by global warming and have instead experienced slight gains in mass unlike most other glaciers around the world here we apply laser altimetry and satellite derived precipitation products to characterize the relationship between the glaciers and precipitation we found a strong correlation r 0 92 p 0 005 between the year to year changes in glacier thickness and precipitation in the pamir and hindu kush from 2003 to 2008 indicating the primary role of precipitation in the glacier changes the amount of precipitation in the glacial region is underestimated by approximately 7 2 times in the gridded precipitation product this underestimation is attributed to the low resolution and lack of orographic precipitation in the gridded products the long term precipitation data show strong interannual variations which probably cause similar variations in glaciers and biases in previous glacier mass change estimates

recent contributions of glaciers and ice caps to sea level rise satellite measurements of earth s gravity field show that the mass loss of glaciers and ice caps contributed to sea level rise by approximately 0 4 millimetres per year between 2003 and 2010 the extent to which mass loss from ice covered land areas contributes to sea level rise is not known accurately in part because previous global estimates use different techniques for glaciers ice caps and ice sheets the gravity recovery and climate experiment grace satellite has provided monthly measurements of the global gravity field since 2002 using grace data jacob et al assess regional mass loss between 2003 and 2010 and conclude that mass loss from ice covered land areas contributed almost 1 5 mm per year to the sea level rise estimated mass loss from the high mountains of asia was negligible in contrast to some other reports glaciers and ice caps gics are important contributors to present day global mean sea level rise1 2 3 4 most previous global mass balance estimates for gics rely on extrapolation of sparse mass balance measurements1 2 4 representing only a small fraction of the gic area leaving their overall contribution to sea level rise unclear here we show that gics excluding the greenland and antarctic peripheral gics lost mass at a rate of 148 30 gt yr 1 from january 2003 to december 2010 contributing 0 41 0 08 mm yr 1 to sea level rise our results are based on a global simultaneous inversion of monthly grace derived satellite gravity fields from which we calculate the mass change over all ice covered regions greater in area than 100 km2 the gic rate for 2003 2010 is about 30 per cent smaller than the previous mass balance estimate that most closely matches our study period2 the high mountains of asia in particular show a mass loss of only 4 20 gt yr 1 for 2003 2010 compared with 47 55 gt yr 1 in previously published estimates2 5 for completeness we also estimate that the greenland and antarctic ice sheets including their peripheral gics contributed 1 06 0 19 mm yr 1 to sea level rise over the same time period the total contribution to sea level rise from all ice covered regions is thus 1 48 0 26 mm 1 which agrees well with independent estimates of sea level rise originating from land ice loss and other terrestrial sources6

accelerated antarctic ice loss from satellite gravity measurements accurate quantification of antarctic ice sheet mass balance and its contribution to global sea level rise remains challenging gravity recovery and climate experiment data spanning the period april 2002 to january 2009 confirm earlier estimates of ice loss for antarctica and indicate that east antarctica started losing mass in about 2006

hydrological processes in the chalk unsaturated zone insights from an intensive field monitoring programme as part of the nerc lowland catchment research programme locar the pang lambourn catchments berkshire uk have been extensively instrumented to provide an improved understanding of the hydrological processes in the unsaturated zone of the chalk a subject of much debate over the past 30 years to quantify the movement of water through the unsaturated zone it is necessary to measure matric potential and water content as well as input and output fluxes from precipitation evapotranspiration and groundwater recharge previous studies have indicated the need for fine temporal resolution data to monitor this system effectively due to the challenges faced in meeting this objective a monitoring scheme was designed that combines a variety of instrumentation to provide the required range accuracy and spatial and temporal resolution of data this paper firstly presents an overview of the monitoring programme and a critical discussion of the instrumentation used subsequently the field data are used to characterise the hydrological properties of the unsaturated zone and to gain insight into recharge processes the interpretation of the data presented in this paper indicate that in the chalk unsaturated zone at west ilsley matrix flow is the dominant recharge mechanism

stratiform manganese mineralisation near inverness scotland a devonian sublacustrine hot spring deposit a stratiform manganiferous horizon up to 4 m thick but localised in aerial extent occurs 10 km south east of inverness in north east scotland it overlies precambrian grampian group schists and is itself overlain by middle old red sandstone devonian conglomerate which elsewhere rests unconformably on the schists the deposit was mined briefly in the early 1920s and is composed principally of fine grained braunite with minor bustamite lower sections of the deposit contain cavities infilled by late baryte calcite and rhodochrosite which resemble stromatactis this horizon is underlain by a hematite quartz layer thought to represent a laterite formed by pre mors weathering of the underlying schists the mineralogy and geochemistry of the manganese ore enriched in ag as ba bi pb sb sr and zn are characteristic of a hydrothermal origin such an origin when considered in conjunction with the outcrop textures mineralogy and stratigraphy of the deposit together with the palaeogeography of the region can only be explained by deposition from hot springs in a sublacustrine environment nearby baryte mineralisation may also have been deposited from the same geothermal system which had the caledonian 407 ma moy granitoid as heat source the managanese ore is enriched in gold pathfinder elements and minor detrital gold has been found in the area gold mineralisation may therefore have also been deposited in the upper sections of this devonian geothermal system