validity of the environmental chloride method for recharge evaluation of coastal aquifers india the work presented in the paper was carried out with the objective of ascertaining the validity of environmental chloride method for evaluation of groundwater recharge to the coastal aquifers situated in semi arid tropical area under the influence of monsoonic type of hydrologic regime towards this end a comparative study using environmental chloride in conjunction with injected tritium method the more commonly used method was undertaken in the coastal aquifers of pondicherry situated about 160 km south of madras along the coast of bay of bengal five each of environmental chloride repeated twice and injected tritium profiles were studied in the alluvium and cuddalore aquifers of pondicherry recharge from the chloride study was estimated using 1 concentration approach which involves estimating the relative enrichment of soil chloride concentration in relation to the input chloride and 2 flux approach determining the turnover time of soil moisture by estimating the total chloride in the profile and yearly input recharge from the injected tritium profiles was estimated by studying the displacement of soil moisture during the time interval between sampling and injection of the tracer repeated chloride profiles show fairly good reproducibility within 15 30 of recharge rates determined by the two approaches for two different sampling times at the same site also the results compare well among the two approaches used for the chloride method mean recharge rates obtained by the injected tritium method for the cuddalores is about 26 cm yr 1 and by the chloride method about 22 cm yr 1 and for the alluvium the respective rates are 10 and 14 cm yr 1 this shows fairly good agreement between the two methods the study thus demonstrates conformity of recharge rates determined by the environmental chloride method and injected tritium technique and proves the validity of the chloride method for recharge measurements for tropical coastal aquifers situated in semi arid regions

elevation changes of ice caps in the canadian arctic archipelago 1 precise repeat airborne laser surveys were conducted over the major ice caps in the canadian arctic archipelago in the spring of 1995 and 2000 in order to measure elevation changes in the region our measurements reveal thinning at lower elevations below 1600 m on most of the ice caps and glaciers but either very little change or thickening at higher elevations in the ice cap accumulation zones recent increases in precipitation in the area can account for the slight thickening where it was observed but not for the thinning at lower elevations for the northern ice caps on the queen elizabeth islands thinning was generally 0 5 m yr 1 which is consistent with what would be expected from the warm temperature anomalies in the region for the 5 year period between surveys and appears to be a continuation of a trend that began in the mid 1980s farther south however on the barnes and penny ice caps on baffin island this thinning was much more pronounced at over 1 m yr 1 in the lower elevations here temperature anomalies were very small and the thinning at low elevations far exceeds any associated enhanced ablation the observations on barnes and perhaps penny are consistent with the idea that the observed thinning is part of a much longer term deglaciation as has been previously suggested for barnes ice cap on the basis of the regional relationships between elevation and elevation change in our data the 1995 2000 mass balance for the archipelago is estimated to be 25 km3 yr 1 of ice which corresponds to a sea level increase of 0 064 mm yr 1 this places it among the more significant sources of eustatic sea level rise though not as substantial as the greenland ice sheet alaskan glaciers or the patagonian ice fields

on the characterization of glacier response by a single time scale glacier response to climate can be characterized by a single time scale when the glacier changes sufficiently slowly then the derivative of volume with respect to area defines a thickness scale similar to that of johannesson and others and the time scale follows from it our version of the time scale is different from theirs because it explicitly includes the effect of surface elevation on mass balance rate which can cause a major increase in the time scale or even lead to unstable response the time constant has a dual role controlling both the rate and magnitude of response to a given climate change data from south cascade glacier washington u s a illustrate the ideas some of the difficulty in obtaining accurate values for the thickness and time scales and the susceptibility of all response models to potentially large errors

tidal fluxes of nutrients and suspended sediments at the north inlet winyah bay national estuarine research reserve beginning june of 1993 suites of 13 water samples have been collected at oyster landing north inlet sc every 20 days covering two consecutive tidal cycles at 2 07 h intervals in order to ascertain whether this large and still growing water chemistry data set can be used to determine tidal fluxes of nutrients and sediments we coupled measured concentrations to estimates of instantaneous tidal discharge based on a basin water storage curve and hindcast tides the mean advective fluxes of all constituents including salt showed statistically significant exports this result however is largely due to an ebb bias in the sampling protocol which resulted in 52 of the samples being collected on ebb tide versus a theoretical percentage of 48 when this bias was corrected by reducing the mean discharge 610 l s 1 to a value 125 l s 1 that produced a balance between the mean advective and dispersive salt fluxes the advective fluxes of the other constituents were reduced to values that are not significantly different from zero in addition to a statistically significant dispersive influx of salt significant dispersive exports were found for don nh4 dop po4 and doc all particulate constituents pn pp iss and oss yielded dispersive fluxes that were not significantly different from zero annual material budgets for the oyster landing basin based on the dispersive fluxes of all constituents except salt are generally similar in magnitude and direction to those measured by dame r f spurrier j d williams t m kjerfve b zingmark r g wolaver t g chrzanowski t h mckeller h n vernberg f j 1991 annual material processing by a salt marsh estuarine basin in south carolina usa marine ecology progress series 72 153e166 in the nearby and ecologically similar bly creek basin indicating that the dispersive fluxes determined in this study are realistic we offer suggestions for improving the reliability and usefulness of future oyster landing water quality data 2006 elsevier ltd all rights reserved

glacier changes in southeast alaska and northwest british columbia and contribution to sea level rise 1 the digital elevation model dem from the 2000 shuttle radar topography mission srtm was differenced from a composite dem based on air photos dating from 1948 to 1987 to determine glacier volume changes in southeast alaska and adjoining canada srtm accuracy was assessed at 5 m through comparison with airborne laser altimetry and control locations measured with gps glacier surface elevations lowered over 95 of the 14 580 km2 glacier covered area analyzed with some glaciers thinning as much as 640 m a combination of factors have contributed to this wastage including calving retreats of tidewater and lacustrine glaciers and climate change many glaciers in this region are particularly sensitive to climate change as they have large areas at low elevations however several tidewater glaciers that had historically undergone calving retreats are now expanding and appear to be in the advancing stage of the tidewater glacier cycle the net average rate of ice loss is estimated at 16 7 4 4 km3 yr equivalent to a global sea level rise contribution of 0 04 0 01 mm yr

contribution of small glaciers to global sea level observed long term changes in glacier volume and hydrometeorological mass balance models yield data on the transfer of water from glaciers excluding those in greenland and antarctica to the oceans the average observed volume change for the period 1900 to 1961 is scaled to a global average by use of the seasonal amplitude of the mass balance these data are used to calibrate the models to estimate the changing contribution of glaciers to sea level for the period 1884 to 1975 although the error band is large these glaciers appear to account for a third to half of observed rise in sea level approximately that fraction not explained by thermal expansion of the ocean

a distributed temperature index ice and snowmelt model including potential direct solar radiation hourly melt and discharge of storglaciaren a small glacier in sweden were computed for two melt seasons applying temperature index methods to a 30 m resolution grid for the melt component the classical degree day method yielded a good simulation of the seasonal patient of discharge but the pronounced melt induced daily discharge cycles were not captured modelled degree day factors calculated for every hour and each gridcell from melt obtained from a distributed energy balance model varied substantially both diurnally and spatially a new distributed temperature index model is suggested attempting to capture both the pronounced diurnal melt cycles and the spatial variations in melt due to the effects of surrounding topography this is accomplished by including a radiation index in terms of potential clear sky direct solar radiation and thus without the need for other data besides air temperature this approach improved considerably the simulation of diurnal discharge fluctuations and yielded a more realistic spatial distribution of melt rates the incorporation of measured global radiation to account for the reduction in direct solar radiation due to cloudiness did not lead to additional improvement in model performance

recharge rate estimation in the mountain karst aquifer system of figeh spring syria figeh watershed spring is one of the important groundwater aquifer which is considered a major source for drinking waters of damascus city and countryside the origin identification and recharge estimates of groundwater are significant components of sustainable groundwater development in this mountain karst aquifer of figeh spring during the period 2001 2009 monthly groundwater and precipitation samples were taken and the isotopic compositions of 18o 2h and chloride contents were analyzed to identify groundwater origins and to estimate recharge rates the 18o 2h of the groundwater show that the groundwater recharge is of meteoric origin the chloride mass balance cmb method was used to quantify recharge rates of groundwater in the mountain karst aquifer of figeh spring the recharge rate varies from 192 to 826 mm year which corresponds to 43 and 67 of the total annual rainfall recharge rates estimated by cmb were compared with values obtained from other methods and were found to be in good agreement this study can be used to develop effective programs for groundwater management and development

correlating check dam sedimentation and rainstorm characteristics on the loess plateau china on the loess plateau china check dams are necessary for soil and water conservation in this study the relationships between check dam sedimentation and storm characteristics were investigated and rainstorm events for an area of data scarcity were reconstructed using optimal regression models four typical check dams of the loess plateau the shipanmao hualiang no 3 guandigou and no 4 guandigou dams were selected for case studies soil profiles behind the four dams were divided into 21 25 31 and 31 layers respectively the one toone link between sediment layers and corresponding storm characteristics were considered based on the peak fallout of 137cs and on the principle that higher flow corresponds to higher sediment deposition volume analysis showed that the layered sediment volume v was closely related to rainfall erosivity r and to the maximum rainfall intensity over 30 min 130 a statistically significant power regression model between v and r was observed along with an exponential regression model between vand i 30 based on the power regression model between v and r a new approach was developed in order to reconstruct rainfall erosivity in rainfall data scarcity areas different hysteresis patterns counterclockwise clockwise and hybrid at the single storm scale were observed between v and r for the shipanmao dam deposition wedge depositional area behind a dam and these impacted differently on the scale reconstruction results however the distance between the reconstructed dams and the known dams had an even stronger influence the scale method developed in this study was shown to perform well and was able to reconstruct rainstorm events for adjacent regions with similar climatic and geomorphological conditions furthermore the results of this study have improved our understanding of single rainstorm dynamics and soil erosion mechanisms on the loess plateau c 2016 elsevier b v all rights reserved

model analyses of the contribution of in channel processes to sediment concentration hysteresis loops summary sediment concentration sc water discharge q relations in rivers are typically governed by multiple and relatively complex processes due to hysteresis effects sediment discharges can differ for similar or equivalent water discharges which causes scatter in empirical datasets and may decrease the predictive power of sc rating curves such hysteresis effects must therefore be understood and accounted for to make dependable predictions for river system management the overall objectives of this study are to develop modelling approaches suitable for reproducing and predicting hysteresis effects at larger scales and to investigate the possible contribution of in channel processes erosion and deposition to sediment concentration hysteresis loops to investigate relevant field scale conditions we develop a one dimensional dynamic sediment transport model of the downstream tuul river northern mongolia investigating in channel processes along a 141 km stretch during a hydrological year the results show that the present modelling approach can reproduce both anti clockwise and clockwise hysteresis effects importantly in channel processes alone can cause considerable anti clockwise hysteresis effects without being reinforced by catchment processes such as hillslope erosion such specific contributions from in channel processes introduced data scatter into the sediment rating curves decreasing their r 2 values from unity to approximately 0 5 to 0 6 more generally possible changes in the number or magnitude of high flow events caused by climatic or other anthropogenic factors could influence total sediment deposition which was primarily found to occur during relatively short high flow events such potential changes also have important implications for the possible spreading of polluted sediments

relation between the mass balance of western canadian mountain glaciers and meteorological data le bilan de masse les bilans d ete et d hiver et l altitude de la ligne d equilibre de 3 glaciers canadiens sont compares avec les donnees meteorologiques de stations avoisinantes pour la periode 1966 1984 presentation de reconstructions statistiques pour les 3 glaciers sur la base des equations de regression avec les enregistrements meteorologiques depuis 1938

recent glacier mass changes in the gulf of alaska region from grace mascon solutions the mass changes of the gulf of alaska goa glaciers are computed from the gravity recovery and climate experiment grace inter satellite range rate data for the period april 2003 september 2007 through the application of unique processing techniques and a surface mass concentration mascon parameterization the mass variations in the goa glacier regions have been estimated at high temporal 10 day and spatial 2 2 arc degrees resolution the mascon solutions are directly estimated from a reduction of the grace k band inter satellite range rate data and unlike previous grace solutions for the goa glaciers do not exhibit contamination by leakage from mass change occurring outside the region of interest the mascon solutions reveal considerable temporal and spatial variation within the goa glacier region with the largest negative mass balances observed in the st elias mountains including the yakutat and glacier bay regions the most rapid losses occurred during the 2004 melt season due to record temperatures in alaska during that year the total mass balance of the goa glacier region was 84 5 gt a 1 contributing 0 23 0 01 mm a 1 to global sea level rise from april 2003 through march 2007 highlighting the large seasonal and interannual variability of the goa glaciers the rate determined over the period april 2003 march 2006 is 102 5 gt a 1 which includes the anomalously high temperatures of 2004 and does not include the large 2007 winter balance year snowfall the mascon solutions agree well with regional patterns of glacier mass loss determined from aircraft altimetry and in situ measurements

relationships among rainfall runoff and suspended sediment in a small catchment with badlands abstract the araguas catchment of the central spanish pyrenees has been monitored since 2004 to study weathering erosion and the hydrological and sediment response to rainfall events in order to understand the hydromorphological dynamics of a badland area in a relatively humid environment this small catchment 0 45 km2 shows highly active processes of physical and chemical weathering related to seasonal variations in temperature and moisture erosion and sediment transport are widely studied in badlands within mediterranean environments because they represent the dominant sediment source to obtain information about suspended sediment and discharge a gauging station was installed within the araguas catchment during the summer of 2005 the aim of this work is to determine the relationships among rainfall runoff and suspended sediment in this badland area towards this goal we analyze the relationships between suspended sediment concentration and discharge during rainfall events from a hydrological viewpoint the araguas catchment reacts to all rainfall events with torrential flow being the most characteristic hydrological response the results obtained between october 2005 and april 2007 reveal extremely high concentrations of suspended sediment with values frequently exceeding 100 g l 1 and reaching a maximum of 1200 g l 1 three different types of hysteretic loops were observed clockwise 22 events 28 counter clockwise 27 events 34 and figure eight 12 events 15 moreover 23 of events were classified as complex hysteretic loops and removed from the analysis due to their complexity clockwise hysteretic floods are characterized by their long duration and the highest hydrological and sedimentological responses counter clockwise hysteretic floods are characterized by their short duration and moderate hydrological and sediment responses finally figure eight hysteretic floods are related to multiple peaks in suspended sediment coinciding with oscillations in discharge associated with the highest rainfall intensities within each event and moderate hydrological and sediment responses

using tracer tests to estimate vertical recharge and evaluate influencing factors for irrigated agricultural systems accurate estimation of groundwater recharge is critical for semi arid regions especially in places like the north china plain ncp where recharge from irrigation and intermittent precipitation events comprises the largest portion of recharge tracer tests were used to estimate potential recharge beneath agricultural systems irrigated by groundwater and to help delineate factors that influence recharge a bromide solution was applied below root regions to trace infiltration in the vadose zone beneath irrigated agricultural fields and non irrigated woodlands at both piedmont plain shijiazhuang and alluvial and lacustrine plain areas hengshui in the ncp the tracer tests lasted for more than 2 years and were conducted at 37 subsites grouped in sets of two to four at 12 regionally distributed sites for the piedmont plain sites the potential recharge rate ranged between 37 466 mm a 6 27 of precipitation plus irrigation p i beneath wheat maize 110 564 mm a 12 52 of p i beneath orchard and 7 10 mm a 1 2 of p i beneath woodlands for the alluvial and lacustrine plain sites the potential recharge rate ranged between 14 177 mm a 2 20 of p i beneath wheat maize 6 57 mm a 0 5 5 of p i beneath orchard 87 279 mm a 10 31 of p i beneath cotton and 6 44 mm a 1 8 of p i beneath woodlands the potential recharge was impacted by various external factors like lithology crops and irrigation when an irrigation controlled experiment was conducted in the same field with the same crop cultivation the results revealed that larger irrigation quantities led to larger potential recharge rates

recharge in karst and dune elements of a semi arid landscape as indicated by natural isotopes and chloride abstract the rates and mechanisms of local recharge in a semi arid environment have been investigated beneath two major landscape settings in the murray basin in south australia these were calcrete flats with sinkholes and sand dunes in adjacent landscape settings five minor settings were investigated and identified as undisturbed calcrete primary older sinkholes secondary younger sinkholes sand dunes with native vegetation and sand dunes with introduced pasture data from a limited series of boreholes were interpreted to suggest that recharge varied from in excess of 100 mm yr 1 for secondary sinkholes to less than 0 1 mm yr 1 beneath sand dunes with native vegetation the data suggest that recharge under sand dunes has increased by more than two orders of magnitude following clearing of the native vegetation 50 yr ago as 90 of an area of 10 000 km2 has been cleared this clearing has ensured that inflow of saline groundwater to the adjacent river murray will increase and in view of the amount of salt stored in both the unsaturated and saturated zones will continue for a very long time at sites where the inferred recharge is lowest profiles of the chloride concentration of soil water are consistent with the hypothesis that there is in excess of 50 000 yr recharge stored in the thick unsaturated zone some evidence for changes in recharge rate over this time scale is seen

the identification of precipitation amount effect with a water isotope enabled threshold model in vadose zone a case study in ordos plateau accurate estimation of precipitation amount recharged to the groundwater is essential to the water balance calculation of a groundwater system in regional scale in the torrid zones the proportion of heavier water isotopes in precipitation presents a negative correlation with the precipitation amount the physical processes explicating this so called amount effect have not been well understood this paper focuses on the d relationships of local precipitation and groundwater to explain the isotopic variability in ordos plateau china in order to better understand the physical process interpreting the amount effect a numerical threshold model in the vadose zone to relate the ineffective precipitation amount and isotopic abundance of precipitation and groundwater was supposed by comparing the modelled d with that in groundwater ineffective precipitation a value of 6 12 mm was obtained in ordos plateau thus the potential groundwater recharge from the precipitation in the region can be deduced the methodology proposed in this study will provide useful insights into the estimation of precipitation contribution to groundwater in other similar areas in the world

present and future states of himalaya and karakoram glaciers a complete glacier inventory of the himalaya and karakoram h k has been created by merging records from the chinese glacier inventory several regional inventories produced by the international centre for integrated mountain development kathmandu nepal and partial inventories from the geological survey of india the only remaining gap the indian part of kashmir has been filled by a reconnaissance inventory based on soviet military maps at 1 200 000 scale representing the late 1970s it contains records for 3526 glaciers covering 9584 km 2 the new h k inventory contains records and outlines for 20 812 glaciers covering 43 178 km 2 the extent of ice in the karakoram is slightly less than in the himalaya but the karakoram glaciers are on average twice as thick 160 m as against 80 m a glacier by glacier analysis relying on estimates of mass balance for the entire mountain range and on an extension of the often used volume area scaling relation suggests that up to about one fifth of the glaciers present in 1985 may have disappeared already if mass loss were to remain constant at the average rate for 1975 2008 from 3000 to 13 000 more glaciers might disappear by 2035 if mass loss were to continue to accelerate as inferred for 1985 2008 only a few thousand to a few hundred glaciers might remain in 2035 total area and total mass would each decrease by about one half constant rate assumption or three quarters constant trend assumption these projections which are uncertain and neglect some possibly important mitigating controls such as variable extents of debris cover and the feedback due to retreat to higher elevations demonstrate the need for more complete analyses to inform public perceptions of and policy decisions relating to the health of h k glaciers

global distributions of glacier properties a stochastic scaling paradigm many problems in global climate and earth systems science require knowledge of regional or global scale distributions of glacier properties which includes mass balance ice velocity flux thickness volume and surface area among others with roughly 160 000 glaciers worldwide obtaining information on the global probability distributions of most ice properties is expensive and often infeasible only surface area distributions are relatively easy to measure either by direct observation or remote sensing while other properties are difficult to observe this work shows that scaling relationships from the continuum dynamics of ice can link the distribution of surface areas to the global and regional distributions of any other continuum property some data inventories already exist for constructing reasonable distributions of glacier sizes and this analysis presents theoretical arguments based on glacier network topologies similar in concept to river networks to suggest a power law times an exponential distribution of surface areas in agreement with the data therefore by using existing data or the theoretical distributions of surface areas specific distributions for other glacier properties in any region of the world can be constructed as an example predictions up to a scaling constant are made for the distribution of glacier volumes characteristic thicknesses characteristic velocities and characteristic response times in the alps

glacier changes in alaska can mass balance models explain grace mascon trends temperature and precipitation data from three weather stations in the st elias mountains of alaska and northwestern canada were used to drive one dimensional 1 d elevation dependent and 0 d degree day mass balance models model outputs were optimized against a 10 day resolution time series of mass variability during 2003 07 obtained from gravity recovery and climate experiment grace mass concentration mascon solutions the models explained 52 60 of the variance in the grace time series modelled mass variations matched the phase of the grace observations and all optimized model parameters were within the range of values determined from conventional mass balance and meteorological observations we describe a framework for selecting appropriate weather stations and mass balance models to represent glacier variations of large regions there is potential for extending these calibrated mass balance models forwards or backwards in time to construct mass balance time series outside of the grace measurement window

estimating groundwater recharge based on mass balance evaluation of unsaturated zone in a coastal catchment characterized by tropical rainforest weather conditions estimation of recharge is necessary for evaluating water resources in the north kelantan catchment of malaysia due to rapid development and consequently over drafting of available groundwater in order to determine the amount of recharge a study of natural salts i e chloride and sulfate was conducted to estimate groundwater recharge rates studies of the chloride mass balance cmb and sulfate mass balance smb were carried out in the unsaturated zone under rainforest weather conditions with a relatively shallow groundwater table ten soil profiles in different parts of the catchment representing a range of soil textures were selected for the study the cmb results showed that the mean recharge rate is 527 87 mm year the highest and lowest calculated recharge rates in the study area were 8 and 31 of local rainfall times required to accumulate chloride sulfate beneath the natural ecosystem highly depend on profile texture and the cmb age is maximized at kp94 and kt121 sites to be 15 01 and 14 15 years respectively the smb method produced lower recharge rates than those based on chloride yielding an average of 364 60 mm year with values ranging between 7 and 26 of local rainfall and the smb age is 21 01 years at kp94 site mobilization decreases with fine texture and low permeability and increases with coarse texture and high permeability in this way low permeability of surface geology not only controls the recharge rate but also causes high buffering in holding salts nevertheless higher sulfate concentration in profile may be due to different dissolution or sorption processes which are required to be studied thoroughly based on two types of scenarios representing natural water movement in unsaturated zone using hydrus 1d recharge rates were simulated to be 419 mm in profile with overlain fine texture soil and 636 mm in profile characterizing with single coarse texture for a total time of 213 days our study suggests the feasibility of using the mass balance methods in tropical rainforest weather conditions the information may improve the accuracy of prediction of possible groundwater pollution and groundwater management in the future

elevation and volume changes on the harding icefield alaska airborne surface elevation profiles of the harding icefield south central alaska were made in 1994 and 1996 thirteen glaciers were profiled along with the upper region of the icefield the profiles were compared to u s geological survey topographic maps made in the 1950s to obtain elevation and volume changes comparison of the changes for the different glaciers shows no significant correlation between volume change and the type of glacier or characteristics such as location aspect size slope or terminus changes estimated total volume change for this 43 year period is about 34 km 3 which corresponds to an area average elevation change of 21 m the estimated error in this elevation change of 5 m is mainly due to errors in the maps at higher elevations our measurements provide an accurate baseline against which future determinations of volume change can be made

isotopic analyses and hydrochemistry of the thermal springs along the eastern side of the jordan dead sea wadi araba rift valley abstract the isotopic composition of the present precipitation as well as the groundwaters of jordan is found to lie between the eastern mediterranean and the meteoric water lines whereas the isotopic compositions of precipitation and groundwater from north and central jordan plot between both lines those of southern jordan cluster closer to the meteoric water line the deep sandstone aquifer complex in central jordan receives water from the overlying tertiary upper cretaceous units as well as from the sandstones of southern jordan both contributions mix in the eastern part of central jordan flow from there in a westerly direction and discharge on the slopes above the dead sea at the interface of fresh groundwater and dead sea water mixing between the latter two waters takes place under a normal geothermal gradient the water is then discharged as thermal water with an isotopic composition following the equation d 3 97 18 o 16 9

a review of aridity and groundwater surface hydrological studies are seen as inadequate in hyperarid and arid areas to provide reliable estimates of recharge in most such areas surface discharges are not present so that assessments of groundwater resources are dependent upon ground interpretation and denied the flow control found in assessments elsewhere groundwater models show that gradients are sustained by long term dewatering and very small amounts of modern indirect recharge recharge indications are well within the error of a hydrological balance discharges appear equally small the development of groundwater in arid areas frequently faces problems of salination due to recycling of irrigation water and rising groundwater heads abstraction is often inadequately managed so that uncontrolled mining of groundwater occurs the advantage that groundwater has however is that it offers staged development and staged appraisal

event sequence and sediment exhaustion in the lower panuco basin mexico abstract although large tropical river systems transport the majority of the world s runoff and sediment few studies have examined the dynamics of suspended sediment transport in this setting this includes mexico which contains two of the larger river basins draining into the gulf of mexico this study provides a detailed analysis of discharge q and suspended sediment transport dynamics for the lower panuco basin 98 227 km2 of eastern mexico including the lower moctezuma lower tamuin and panuco rivers daily values of discharge and suspended sediment concentration ssc are examined for three stations spanning from the late 1950s to early 1990s although the panuco is a large basin the relationship between discharge and suspended sediment concentration represents a departure from the oft reported study by heidel trans am geophys union 37 1956 56 instead of sediment lagging discharge the sediment wave precedes discharge by an average of 1 7 days displaying pronounced clockwise positive hysteresis this may be due to the sources of runoff and sediment which are derived primarily in the lower reaches of the basin because of precipitation patterns geology and basin morphometry the distinct differences in lithology between the tamuin and moctezuma basins which join in the coastal plain to form the rio panuco allow the influence of geologic setting to be considered q ssc relations display positive hysteresis where the sediment is derived from erodible tertiary shale deposits in the moctezuma basin in contrast q ssc relations in the rio tamuin which transports less suspended sediment because of its karstic setting are more linear due to these relations being dependent on the entrainment of bed material consideration of the sequence of events during the rainy season suggests that much of the hillslope derived sediment is flushed through the system by early events which would occur because of exhaustion of hillslopes sediments q ssc relations are increasingly linear during later events in the rio panuco which is likely due to these events transporting a higher proportion of sediment entrained from the channel this is manifest by a reduction in lead times as the number of days between peak ssc and peak q for early and late events significantly decreases from 2 6 to 0 9 respectively large events 750 m3 s in the latter part of summer and early fall having high suspended sediment concentrations could be due to the replenishment of hillslope sediments or due to the contribution of sediment from source areas that were not previously exhausted the findings from this study are likely common to most drainage systems having seasonal bimodal streamflow regimes whereas the seasonal signature of q ssc relations is likely enhanced in those settings where agriculture is a major component of the landscape

contribution of glacier melt to sea level rise since ad 1865 a regionally differentiated calculation the contribution of glacier melt including the greenland ice sheet to sea level change since ad 1865 is estimated on the basis of modelled sensitivity of glacier mass balance to climate change and historical temperature data calculations are done in a regionally differentiated manner to overcome the inhomogeneity of the global distribution of glaciers a distinction is made between changes in summer temperature and in temperature over the rest of the year our best estimate of the ice melt in the period 1865 1990 in terms of sea level change equivalent is 5 7 cm 2 7 cm for glaciers and 3 0 cm for the greenland ice sheet additional calculations show that simpler methods like using annual or even global mean temperature anomaly give estimates that differ by up to 55 consequently a regionally differentiating approach is advised for making projections of glacier melt with gcm output

spatial scale dependence of sediment dynamics in a gullied rolling loess region on the loess plateau in china sediment dynamics is still imperfectly understood especially at spatial scale in the highly erodible region of the loess plateau and few studies have been heretofore conducted using 5 year continuous water and sediment records three plots and three basins in the gullied rolling loess region were selected and sediment dynamics at spatial scale was studied results showed that the floods where the peak discharge qp did not come earlier than the sediment peak were predominant in slope zones occupying 90 and 70 of the total for the mao slope and for the entire slope respectively however in basins most of the sediment peaks cp lagged behind qp implying that slope zone was the main origin of sediment more than 50 of the events presented clockwise hysteresis loops in the mao slope area while almost all the events had anticlockwise hysteresis loops in basins this can be attributed to less occurring frequency of hyperconcentrated flow as well as its instability in slope zones compared to those in the basins within these contexts gravitational erosion made the highest sediment concentration c in tuanshangou basin and median developing status of c discharge c q relationships in the entire slope area this study provides insights into the protection of slope surface and disruption of the development of hyperconcentrated flow to reduce soil loss

mass balance in the glacier bay area of alaska usa and british columbia canada 1995 2011 using airborne laser altimetry the glacier bay region of southeast alaska usa and british columbia canada has undergone major glacier retreat since the little ice age lia we used airborne laser altimetry elevation data acquired between 1995 and 2011 to estimate the mass loss of the glacier bay region over four time periods 1995 2000 2000 05 2005 09 2009 11 for each glacier we extrapolated from center line profiles to the entire glacier to estimate glacier wide mass balance and then averaged these results over the entire region using three difference methods normalized elevation area weighted method and simple average we found that there was large interannual variability of the mass loss since 1995 compared with the long term post lia average for the full period 1995 2011 the average mass loss was 3 93 0 89 gt a 1 0 6 0 1 m w e a 1 compared with 17 8 gt a 1 for the post lia 1770 1948 rate our mass loss rate is consistent with grace gravity signal changes for the 2003 10 period our results also show that there is a lower bias due to center line profiling than was previously found by a digital elevation model difference method

the mass balance of mccall glacier brooks range alaska u s a its regional relevance and implications for climate change in the arctic mccall glacier has the only long term mass balance record in arctic alaska average annual balances over the periods 1958 72 and 1972 93 were 15 and 33cm respectively recent annual balances 1993 96 are about 60 cm and the mass balance gradient has increased for an arctic glacier with its low mass exchange rate this marks a significant negative trend recently acquired elevation profiles of mccall glacier and ten other glaciers within a 30 km radius were compared with topographic maps made in 1956 or 1973 most of these glaciers had average annual mass balances between 25 and 33 cm while mccall glacier averaged 28 cm for 1956 93 indicating that it is representative of the region in contrast changes in terminus position for the different glaciers vary markedly thus mass balance trends in this region cannot be estimated from fractional length changes at time scales of a few decades we developed a simple degree day accumulation mass balance model for mccall glacier the model was tested using precipitation and radiosonde temperatures from weather stations at inuvik canada and barrow kaktovik and fairbanks alaska and was calibrated with the measured balances the inuvik data reproduce all measured mass balances of mccall glacier well and also reproduce the long term trend towards more negative balances data from the other stations do not produce satisfactory model results we speculate that the arctic front oriented east west in this region causes the differences in model results

sediment concentration versus water discharge during single hydrologic events in rivers relations between sediment concentration c and water discharge q for a hydrologic event such as a flood are studied qualitatively by analyzing smoothed temporal graphs discharge and concentration vs time in terms of mode spread and skewness comparing cq ratios at a given discharge on the rising and falling limbs of the discharge hydrograph provides a consistent reliable method for categorizing c q relations five common classes of such relations are single valued straight or curved clockwise loop counterclockwise loop single valued plus a loop and figure eight temporal graph mode and skewness influence the type of relation whereas temporal graph spread affects the details of the particular c q relation its graphical breadth shape orientation and plotted location field examples of the various types of relations are given including varieties that heretofore have received little attention such as the figure eight explanations for each type of c q relation are discussed

fingerprinting suspended sediment sources in the catchment of the river ouse yorkshire uk statistically verified composite fingerprints and a multivariate mixing model have been employed to establish the main sources of the suspended sediment transported through the lower non tidal reaches of the river ouse and one of its main tributaries the river wharfe during the period 1994 1997 in the case of the suspended sediment samples collected from the river ouse the load weighted mean contributions from uncultivated topsoil cultivated topsoil and channel bank sources were estimated to be c 25 38 and 37 respectively while for the river wharfe these sources contributed c 70 4 and 23 respectively c 4 was derived from woodland topsoil suspended sediment samples collected during higher flows evidenced a greater contribution from channel banks than samples collected during lower flows source materials were also differentiated according to the three main geological source areas carboniferous permian and triassic and jurassic and their load weighted mean contributions were estimated to be c 24 41 and 35 for the river ouse and c 91 9 and 0 there are no jurassic rocks in this catchment for the river wharfe respectively when suspended sediment samples from tributary streams were used to characterize each geological source area the equivalent results for the river ouse were c 30 46 and 24 considering the three main tributaries that contribute to the river ouse the load weighted mean contributions from the rivers swale ure and nidd were estimated to be 82 15 and 3 respectively these values have been compared with estimates of the relative magnitude of the annual suspended sediment loads of these three rivers for the years 1995 and 1996 derived from continuous monitoring of discharge and turbidity differences between the two sets of results are ascribed to the different periods of record involved and to the timing of suspended sediment sampling relative to the overall storm hydrograph and thus the degree to which the available samples are representative of the overall suspended sediment flux although a number of limitations must be recognized the fingerprinting approach to source ascription is seen as providing valuable information regarding suspended sediment sources in the study catchments copyright 1999 john wiley sons ltd

influence of irrigation practices on arsenic mobilization evidence from isotope composition and cl br ratios in groundwater from datong basin northern china environment isotopes 18o and 2h and cl br ratios in groundwater have been used to trace groundwater recharge and geochemical processes for arsenic contamination in datong basin the arsenic concentrations of groundwater samples ranged from 0 4 to 434 9 g l with the average of 51 2 g l which exceeded china s drinking water standard 10 g l all the groundwater samples are plotted on or close to the meteoric water line of the 18o vs 2h plot indicating their meteoric origin the relationship between 18o values and cl br ratios and cl concentrations demonstrate that leaching and mixing are the dominant processes affecting the distribution of high arsenic groundwater in this area the observed non linearity in the trend between 18o and arsenic concentration is due to combined effects of mixing and leaching the similarity of the trend in cl br ratios and 18o values for high arsenic groundwater demonstrate that extensive leaching of irrigation return and salt flushing water flow could be the dominant process driving arsenic mobilization in the groundwater system moreover the long term irrigation practice can cause the drastic change of the biogeochemical and redox condition of in the aquifer system which in turn promotes the mobilization of arsenic therefore groundwater pumping for irrigation in this area of waterborne endemic arsenic poisoning should be under strict control to protect groundwater quality in this area

sulfur cycling in the yellow river and the sulfate flux to the ocean abstract river sulfate flux is a major input into the ocean reservoir and plays a critical role in the global sulfur cycle constrained riverine sulfate isotope compositions are useful in gaining a better understanding of the secular changes in the sulfur isotopic value 34sso4 of the ocean the sulfate flux from rivers flowing through arid areas is often ignored due to their low water discharge but these rivers generally contain large amounts of sulfate duo to water condensation gypsum dissolution and anthropogenic effluents hence their effects on the global sulfur cycle are still unclear the yellow river yr flows across the eastern qinghai tibet plateau qtp and arid chinese loess plateau clp with a length of 5464 km as one typical large river flowing across arid climate areas coupled with extensive human activities in the world the yr is an ideal site to illustrate this problem the riverine sulfate sources in the different reaches of the yr were determined by 34sso4 and 18oso4 values and sulfur cycling concept model in the yellow river basin yrb was established to explain the natural and anthropogenic effects on sulfate flux coupled with 34sso4 values from the yr to the ocean our data showed that gypsum derived sulfate controls the 34sso4 of the yr and its contribution increased from 30 to 90 downstream with mean values of 71 84 and 87 for the upstream midstream and downstream segments of the river respectively the annual sulfate flux to the ocean ranges from 0 026 tmol yr to 0 043 tmol yr with an average of 0 036 tmol yr in this century and the average flux weighted 34sso4 value was 8 5 compared with the natural global riverine sulfate flux to the ocean the yr contributes nearly 1 1 of the sulfate flux this combined with its positive 34sso4 value makes this arid area an important contributor to the sulfate flux and the global sulfur cycle

a macroscopic approach to glacier dynamics a simple approach to glacier dynamics is explored in which there is postulated to be a relationship between area and volume with three parameters the time for area to respond to changes in volume a thickness scale and an area characterizing the condition of the initial stale this approach gives a good fit to the measurements of cumulative balance and area on south cascade glacier from 1970 97 the area time scale is roughly 8 years the thickness scale about 123 m and the 1970 area roughly 4 larger than required for adjustment with volume combining this relationship with a version of mass continuity expressed in terms of area and volume produces a theory of glacier area and volume response to climate in which another time constant the volume time scale appears area and volume both respond like a damped spring and mass system the damping of the south cascade response is approximately critical and the volume time scale is roughly 48 vexes six times the area time scale the critically damped spring and mass analogy reproduces the time dependence predicted by the more complicated traditional theory of nyc

variation of δ18o δd and 3h in karst springs of south kashmir western himalayas india water samples were collected from cold and warm karst springs for stable isotopes 18o and d and 3h from se of kashmir valley western himalayas to distinguish the sources of recharge and infer their recharge areas the spring water samples were most depleted in heavier isotopes in may average 18o 8 87 and d 50 3 and enriched in september average 18o 7 58 and d 48 1 the depleted 18o and 2h of spring waters bear the signatures of winter precipitation while as the enriched 18o and 2h of spring waters bear the signature of summer rainfall d excess and 3h corroborate with the stable isotope results that the spring flow in spring season may and autumn september is dominantly controlled by the melting of winter snowmelt and summer rainfall respectively the results showed that unlike d the 18o value in the karst spring waters decreases in january suggesting 18o shift the spring water samples also fall above the local meteoric water line and global meteoric water line indicating the 18o shift due to interaction of groundwater with the host carbonate rocks during its traverse the mean elevation of the recharge areas of the springs using 18o and d tracers was also estimated copyright 2014 john wiley sons ltd

response time of glaciers as a function of size and mass balance 1 theory a simple interpretation of the traditional definitions of glacier and ice sheet response time e g thickness divided by mass balance rate h b suggests that larger glaciers respond more slowly than small glaciers to a perturbation in climate however with reasonable choices for mass balance behavior a scaling analysis shows that the response time of valley glaciers decreases as a function of increasing size when other variables are held constant in essence this is because larger valley glaciers push further into the ablation zone and ablation increases more rapidly than the thickness so that h b gets smaller ice sheets have different mass balance regimes than valley glaciers and as they grow larger the ablation does not increase faster than the thickness therefore as ice sheets grow in surface area the response time increases for both ice sheets and valley glaciers the response time also depends on a mass balance index which is defined as the slope of the balance curve as a function of horizontal distance along the glacier surface rather than elevation the response time decreases as the balance index increases so for valley glaciers an increase in the balance index and an increase in glacier size have opposite effects on the response time the balance index is typically larger for smaller valley glaciers therefore a small glacier will typically respond faster than a large glacier but this quicker response is because of mass balance considerations and not because of the dynamic characteristics of the glacier arising from its small size as often assumed

airborne and spaceborne dem and laser altimetry derived surface elevation and volume changes of the bering glacier system alaska usa and yukon canada 1972 2006 using airborne and spaceborne high resolution digital elevation models and laser altimetry we present estimates of interannual and multi decadal surface elevation changes on the bering glacier system alaska usa and yukon canada from 1972 to 2006 we find 1 the rate of lowering during 1972 95 was 0 9 0 1 m a 1 2 this rate accelerated to 3 0 0 7 m a 1 during 1995 2000 and 3 during 2000 03 the lowering rate was 1 5 0 4 m a 1 from 1972 to 2003 70 of the area of the system experienced a volume loss of 191 17 km 3 which was an area average surface elevation lowering of 1 7 0 2 m a 1 from november 2004 to november 2006 surface elevations across bering glacier from mcintosh peak on the south to waxell ridge on the north rose as much as 53 m up glacier on bagley ice valley about 10 km east of juniper island nunatak surface elevations lowered as much as 28 m from october 2003 to october 2006 nasa terra modis observations from may to september 2006 indicated muddy outburst floods from the bering terminus into vitus lake this suggests basal englacial hydrologic storage changes were a contributing factor in the surface elevation changes in the fall of 2006

the physical basis of glacier volume area scaling ice volumes are known for only a few of the roughly 160 000 glaciers worldwide but are important components of many climate and sea level studies which require water flux estimates a scaling analysis of the mass and momentum conservation equations shows that glacier volumes can be related by a power law to more easily observed glacier surface areas the relationship requires four closure choices for the scaling behavior of glacier widths slopes side drag and mass balance reasonable closures predict a volume area scaling exponent which is consistent with observations giving a physical and practical basis for estimating ice volumes glacier volume is insensitive to perturbations in the mass balance scaling but changes in average accumulation area ratios reflect significant changes in the scaling of both mass balance and ice volume

synchronous retreat and acceleration of southeast greenland outlet glaciers 2000 06 ice dynamics and coupling to climate a large portion of the recent increase in the rate of mass loss from the greenland ice sheet is from increased outlet glacier discharge along its southeastern margin while previous investigations of the region s two largest glaciers suggest that acceleration is a dynamic response to thinning and retreat of the calving front it is unknown whether this mechanism can explain regional acceleration and what forcing is responsible for initiating rapid thinning and retreat we examine seasonal and interannual changes in ice front position surface elevation and flow speed for 32 glaciers along the southeastern coast between 2000 and 2006 while substantial seasonality in front position and speed is apparent nearly all the observed glaciers show net retreat thinning and acceleration with speed up corresponding to retreat the ratio of retreat to the along flow stress coupling length is proportional to the relative increase in speed consistent with typical ice flow and sliding laws this affirms that speed up results from loss of resistive stress at the front during retreat which leads to along flow stress transfer large retreats were often preceded by the formation of a flat or reverse sloped surface near the front indicating that subsequent retreats were influenced by the reversed bed slope many retreats began with an increase in thinning rates near the front in the summer of 2003 a year of record high coastal air and sea surface temperatures this anomaly was driven in part by recent warming suggesting that episodes of speed up and retreat may become more common in a warmer climate

width and length scaling of glaciers an analysis of hundreds of mountain and valley glaciers in the former soviet union and the alps shows that characteristic glacier widths scale as characteristic glacier lengths raised to an exponent of 0 6 this is in contrast to most previous analyses which implicitly or explicitly assumed scaling exponents of either 0 or 1 the exponent 0 6 implies that average glacier widths are proportional to average glacier thicknesses although this seems to suggest v shaped glacier valleys the linear width thickness relationship is not inconsistent with parabolic valley cross sections because the characteristic or average width of a glacier depends on many other aspects of channel and glacier morphology including variations in the channel width with distance up and downstream

anti clockwise hysteresis in suspended sediment concentration during individual storms holbeck catchment yorkshire england abstract analysis of the flow sediment hysteresis shape may assist in determining the sediment source area in a small basin a clockwise hysteresis occurs when sediment is derived from the bed and banks of the channel or areas adjacent to the channel whereas an anti clockwise hysteresis occurs when the upper part of the slopes is the sediment source area

grain size characteristics of suspended sediment in the yellow river china abstract based on the data from the yellow river and its tributaries a systematic study has been made of the spatial and temporal variations in grain size feature of suspended sediment the grain size characteristics of suspended sediment in the yellow river basin are closely influenced by precipitation seasonal alternations of wind and water action and the nature of surface materials the lower the mean annual precipitation the stronger the wind action the coarser the surface loess materials the coarser is the suspended sediment in particular grain size characteristics of suspended sediment of the middle yellow river s tributaries are controlled by hyperconcentrated flows with suspended sediment concentrations of 300 000 400 000 mg l or more at a station the relationship between grain size and suspended sediment exhibits two peaks with percentages of the 0 05 mm suspended sediment occurring at both low and very high suspended sediment concentrations based on the data from all the tributaries of the middle yellow river an optimal grain size composition of suspended sediment has been identified that leads the annual suspended sediment concentration to the highest values the long term variation of grain size suspended sediment in the yellow river can be related to variations in precipitation and human activities the 30 year record from longmen station shows that during the 1960s the suspended sediment size increased but since the 1970s it has declined controlled by the influencing factors grain size of suspended sediment in the middle yellow river decreases from northwest to southeast

where glaciers meet water subaqueous melt and its relevance to glaciers in various settings glacier change is ubiquitous but the fastest and largest magnitude changes occur in glaciers that terminate in water this includes the most rapidly retreating glaciers and also several advancing ones often in similar regional climate settings furthermore water terminating glaciers show a large range in morphology particularly when ice flow into ocean water is compared to that into freshwater lakes all water terminating glaciers share the ability to lose significant volume of ice at the front either through mechanical calving or direct melt from the water in contact here we present a review of the subaqueous melt process we discuss the relevant physics and show how different physical settings can lead to different glacial responses we find that subaqueous melt can be an important trigger for glacier change it can explain many of the morphological differences such as the existence or absence of floating tongues subaqueous melting is influenced by glacial runoff which is largely a function of atmospheric conditions this shows a tight connection between atmosphere oceans and lakes and glaciers subaqueous melt rates even if shown to be large should always be discussed in the context of ice supply to the glacier front to assess its overall relevance we find that melt is often relevant to explain seasonal evolution can be instrumental in shifting a glacier into a different dynamical regime and often forms a large part of a glacier s mass loss on the other hand in some cases melt is a small component of mass loss and does not significantly affect glacier response

airborne surface profiling of glaciers a case study in alaska a relatively lightweight and simple airborne system for surface elevation profiling of glaciers in narrow mountain valleys has been developed and tested the aircraft position is determined by kinematic global positioning system gps methods the distance to the glacier surface is determined with a laser ranger the accuracy is about 0 3 m sufficient to permit future changes to be observed over short time intervals long term changes can be estimated by comparison of profiles with existing maps elevation profiles obtained in 1993 94 from three glaciers in central and south central alaska are compared with maps made about 1950 the resulting area averaged seasonally corrected thickness changes during the interval are gulkana glacier central alaska range 11 m worthington glacier central chugach mountains 7 m and bear lake glacier kenai mountains 12 m all three glaciers retreated during the interval of comparison the estimated uncertainty in the average thickness change is 5 m which is mainly due to errors in the existing maps constraints on the accuracy of the maps are obtained by profiling in proglacial areas

an extended perfect plasticity method for estimating ice thickness along the flow line of mountain glaciers 1 direct measurement of the thickness of mountain glaciers is difficult over large areas yet knowledge of the thickness is essential for calculating their volumes and future evolution we develop a new method for estimating the ice thickness along glacier flow lines using the perfect plasticity rheological assumption that relates the thickness and surface slope to a yield stress previous studies have used this assumption with the shallow ice approximation to estimate the ice thickness but the standard approach neglects the effect of side drag on glacier stress balance our method addresses this shortcoming and extends the standard method by accounting for the side drag via the glacier width besides the assumed yield stress the inputs for our method are the outline and surface topography of the glacier surface velocity and mass balance data are unnecessary we validated the extended method on five glaciers in northwest china where thickness data are available from radio echo soundings finding that it can reproduce measured thicknesses with a mean absolute error of 11 8 like the standard method moreover for long glacier tongues confined to flow between parallel valley sides this method is found to give more accurate thickness estimates than does the standard method with a mean absolute error of as low as 5 3 sensitivity analysis shows that the estimated ice thickness depends strongly on yield stress and surface slope and less strongly on glacier width because this method is physically more realistic than the standard method and its inputs are easily derivable from remote sensing observations it has the potential to be used for processing large glacier data sets

mass balance of glaciers other than the ice sheets small glaciers appear to have been at equilibrium or shrinking very slightly during 1961 90 according to analysis of an essentially compl ete set of published measurements simple calculations give an average annual mass balance of 195 59 mm a 1 water equivalent but this is too low because of systema tic errors eglect of internal accumulation is respon sible for some tens of millime ters of under esti mate uneven spatial coverage with fewer measurements where mass balances are less negative accounts for about 50 mm a 1 of underestimate this figure derives from spatial interpolati on based on global data on ice extent and on an analysis of correlations between balance time series the eorrelogram shows exponential decay the scale length being about 600 km the largest bias is due to a newly detec ted dependence of mass balance on glacier size among the 231 measured glaciers many arc small and belong to a restricted size range in which balance is negativ e but much of the small glacier extent is accounted for by larger glac iers in a size range where balance is indisti ngui shable from zero correct ing for this size bias increases the average balance to 35 89 mm a i inspection of time series for 1940 95 251 glaciers shows that mass balance was least negative during the 1960s and has varied in broad agreementvith northern hemisphere temperature anomalies smaller small glaciers a 16 km2 appear to be more sensitive than larger small glaciers to changes in thermal forci ng the small glaci er contribution to sea level rise implied by this asse ssment is only 0 06 0 32 mm a i consistent with glaciers in general mak i ng little or no contri bution to sea level change during 1961 90

chloride hydrochemical and isotope methods of groundwater recharge estimation in eastern mediterranean areas a case study in jordan jordan is classified as an arid to semi arid country with a population according to 1999 estimates of 4 8 millions inhabitants and a growth rate of 3 4 efficient use of jordan s scarce water is becoming increasingly important as the urban population grows this study was carried out within the framework of the joint european research project groundwater recharge in the eastern mediterranean and describes a combined methodology for groundwater recharge estimation in jordan the chloride method as well as isotopic and hydrochemical approaches recharge estimations using the chloride method range from 14 mm year 1 mean annual precipitation of 500 mm for a shallow and stony soil to values of 3 7 mm year 1 for a thick desert soil mean annual precipitation of 100 mm and values of well below 1 mm year 1 for thick alluvial deposits mean annual rainfall of 250 mm isotopically most of the groundwater in the hammad basin east jordan falls below the global meteoric water line and far away from the mediterranean meteoric water line suggesting that the waters are ancient and were recharged in a climate different than mediterranean tritium levels in the groundwater of the hammad basin are less than the detection limit 1 3 tu however three samples in east hammad where the aquifer is unconfined present tritium values between 1 and 4 tu copyright 2007 john wiley sons ltd

hydrogeochemical and isotopic evidences of the groundwater regime in datong basin northern china datong basin is one of the cenozoic faulted basins in northern china s shanxi province where groundwater is the major source of water supply the results of hydrochemical investigation show that along the groundwater flow path from the margins to the lower lying central parts of the basin groundwater generally shows increases in concentrations of tds hco3 so42 cl na and mg2 except for ca2 content along the basin margin groundwater is dominantly of ca hco3 type however in the central parts of the basin it becomes more saline with na hco3 dominant or mixed ion type the medium deep groundwater has chemical compositions similar to those of shallow groundwater except for the local area affected by human activity from the mountain front to the basin area shallow groundwater concentrations of major ions increase and are commonly higher than those in medium deep aquifers due to intense evapotranspiration and anthropogenic contamination hydrolysis of aluminosilicate and silicate minerals cation exchange and evaporation are prevailing geochemical processes occurring in the aquifers at datong basin the isotopic compositions indicate that meteoric water is the main source of groundwater recharge evaporation is the major way of discharge of shallow groundwater the groundwater in medium deep aquifers may be related to regional recharges of rainwater by infiltrating along the mountain front faults and of groundwater permeating laterally from bedrocks of the mountain range however in areas of groundwater depression cones groundwater in the deep confined aquifers may be recharged by groundwater from the upper unconfined aquifer through aquitards

interpreting sediment delivery processes using suspended sediment discharge hysteresis patterns from nested upland catchments south eastern australia in this study suspended sediment concentration ssc and discharge q hysteresis patterns recorded at the outlets of two nested upland catchments in south eastern australia were examined detailed monitoring of sediment flux was undertaken in a 1 64 km2 sub catchment located within a 53 5 km2 catchment for which sediment yield was measured and the extent of incised channels mapped the analysis of ssc q hysteresis patterns was supplemented by these additional datasets to contribute to the explanation of observed patterns clockwise ssc q hysteresis loops with the suspended sediment peak leading the discharge peak were recorded most frequently at both sites this was attributed to initial rapid delivery of sediment from channel banks the dominant sediment source in the sub catchment and probably also for the catchment in conjunction with remobilization of in channel fine sediment deposits sediment exhaustion effects were considered to enhance clockwise hysteresis with reduced ssc on the falling limb of event hydrographs pronounced exhaustion effects were observed on some multi rise events with subsequent flow peaks associated with much reduced sediment peaks to compare ssc q hysteresis patterns between the two catchments a dimensionless similarity function sf was derived to differentiate paired event hysteresis patterns according to the extent of pattern similarity this analysis coupled with the other datasets provided insight into the function of erosion and sediment delivery processes across the spatial scales examined and indicated the dependency of between scale suspended sediment transfer on defined flow event scenarios quantitative measures of event ssc q hysteresis pattern similarity may provide a mechanism for linking the timing and magnitude of process response across spatial scales this may offer useful insights into the between scale linkage of dominant processes and the extent of downstream suspended sediment delivery copyright 2009 john wiley sons ltd

monsoonal influence on variation of hydrochemistry and isotopic signatures implications for associated arsenic release in groundwater summary the present study examines the groundwater and surface water geochemistry of two different geomorphic domains within the chakdaha block west bengal in an attempt to decipher potential influences of groundwater abstraction on the hydrochemical evolution of the aquifer the effect of different water inputs monsoon rain irrigation and downward percolation from surface water impoundments to the groundwater system and concomitant as release a low land flood plain and a natural levee have been selected for this purpose although the stable isotopic signatures of oxygen 18o and hydrogen 2h are largely controlled by local precipitation the isotopic composition falls sub parallel to the global meteoric water line gmwl the cl br molar ratio indicates vertical recharge into the wells within the flood plain area especially during the post monsoon season while influences of both evaporation and vertical mixing are visible within the natural levee wells increase in mean doc concentrations from 1 33 to 6 29 mg l from pre to post monsoon season indicates possible inflow of organic carbon to the aquifer during the monsoonal recharge concomitant increase in ast fe ii and hco3 highlights a possible initial episode of reductive dissolution of as rich fe oxyhydroxides the subsequent sharp increase in the mean as iii proportions by 223 particularly in the flood plain samples during the post monsoon season which is accompanied by a slight increase in mean ast 7 may refer to anaerobic microbial degradation of doc coupled with the reduction of as v to as iii without triggering additional as release from the aquifer sediments

contrasting the indian and east asian monsoons implications on geologic timescales the surface winds over the arabian sea and south china sea are meaningful indicators for the strength of the indian monsoon and east asian monsoon respectively paleo monsoon variability has been studied through analysis of sediment records from these two monsoon regions to facilitate interpretation of these records we focus on the impacts of internal and external forcing of the monsoon system by contrasting the annual cycle and interannual variability of two subsystems the monsoon over the indian sector 40 105 e and over the east asian sector 105 160 e differences in the annual cycle within these subsystems arise primarily from the different land ocean configurations that determines atmospheric response to the solar forcing thus factors that drive intensities of the monsoonal annual cycle share common features with the external geographic and orbital forcing that controls paleomonsoon variability we show that the differences in interannual variations between the two monsoon subsystems are primarily due to internal factors of the coupled atmosphere ocean land system such as remote impacts of el nin o la nin a and local monsoon ocean interactions the mechanisms that operate on interannual to interdecadal timescales may differ fundamentally from that on geologic orbital timescales the low level flows over the east asia and australia are essentially established by geographic forcing the amplification of the australia summer monsoon during increased solar precession is likely caused by an enhanced east asian winter monsoon rather than following an enhanced indian summer monsoon as on the interannual timescale it is also found that el nin o influences the low level flow moderately over the arabian sea but to a greater extent over the south china sea as such large changes in the pacific thermal conditions may significantly alter the intensity of the east asian monsoon but not the indian monsoon

chemical weathering in the upper huang he yellow river draining the eastern qinghai tibet plateau we examined the fluvial geochemistry of the huang he yellow river in its headwaters to determine natural chemical weathering rates on the northeastern qinghai tibet plateau where anthropogenic impact is considered small qualitative treatment of the major element composition demonstrates the dominance of carbonate and evaporite dissolution most samples are supersaturated with respect to calcite dolomite and atmospheric co2 with moderate 0 710 0 715 87 sr 86 sr ratios while six out of 21 total samples have especially high concentrations of na ca mg cl and so4 from weathering of evaporites we used inversion model calculations to apportion the total dissolved cations to rain evaporite carbonate and silicate origin the samples are either carbonate or evaporite dominated but the relative contributions of the four sources vary widely among samples net co2 consumption rates by silicate weathering 6 120 10 3 mol km 2 yr are low and have a relative uncertainty of 40 we extended the inversion model calculation to literature data for rivers draining orogenic zones worldwide the ganges brahmaputra draining the himalayan front has higher co2 consumption rates 110 570 10 3 mol km 2 yr and more radiogenic 87 sr 86 sr 0 715 1 24 than the upper huang he but the rivers at higher latitudes are similar to or lower than the upper huang he in co2 uptake by silicate weathering in these orogenic zones silicate weathering rates are only weakly coupled with temperature and become independent of runoff above 800 mm yr copyright 2005 elsevier ltd

discharge sediment dynamics of the lower mississippi river abstract temporal and spatial variations of processes in the lower 315 mi of the mississippi river were investigated the data base consisted of several instantaneous measurements of discharge suspended sediment concentration suspended sediment load and percentage of sand in the suspended load the data were collected periodically by the corps of engineers at tarbert landing n 460 between 1972 and 1985 at st francisville n 84 between 1978 and 1986 and at belle chasse n 93 between 1977 and 1986 physical factors that contribute to seasonal and annual variations in sediment load and concentration include the magnitude duration number and timing of floods and the background flow conditions during high flow years sediment peaks precede discharge peaks by several months and depletion occurs during and after the maximum discharge during low flow years sediment peaks occur only shortly before or coincide with discharge peaks unexplained sediment peaks during both falling and rising stages may be caused by bank failures or turbulent fluctuations of stream velocity silt clay and sand concentrations follow different functions with discharge and fit different exponents with sand being steeper the total suspended sediment concentration is a composite of these components at upstream stations the silt clay concentration was depleted and showed a strong nonlinear relationship with discharge but the sand concentration showed a linear relationship with discharge downstream the silt clay and sand concentrations showed more linear relationships with discharge quadratic power functions produced better correlations than the linear power functions in most cases

elevation volume and terminus changes of nine glaciers in north america nine glaciers in alaska and washington u s a originally mapped as part of the international geophysical year igy in 1957 58 were re mapped between 1993 and 1996 eight using airborne surface elevation profiling and the ninth using ground based kinematic global positioning system methods elevation volume and terminus changes were determined for the approximately 38 year period between the igy mapping and the profiling all nine glaciers showed substantial thinning at lower elevations seven of the nine thickened at higher elevations none of the glaciers had a significant net volume increase two had close to zero change and the others had a decrease for the eight glaciers for which we could obtain quantitative information the mean thickness change was 10 m with a large scatter 8 m standard deviation the volume and terminus changes had no clear geographic pattern and no simple relationship between volume change and terminus advance or retreat was identified the largest error in the estimated volume changes is due to map errors

sharply increased mass loss from glaciers and ice caps in the canadian arctic archipelago the canadian arctic archipelago contains one third of the global volume of land ice outside the ice sheets but its contribution to sea level change is largely unknown gardner et al use three independent techniques to reveal that mass loss from the archipelago was 92 12 gigatonnes per year in 2007 09 about three times greater than in 2004 06 and coincident with warmer summer temperatures the record is too short to allow a firm conclusion on longer term trends but it is clear that the canadian arctic archipelago is a significant contributor to sea level rise mountain glaciers and ice caps are contributing significantly to present rates of sea level rise and will continue to do so over the next century and beyond1 2 3 4 5 the canadian arctic archipelago located off the northwestern shore of greenland contains one third of the global volume of land ice outside the ice sheets6 but its contribution to sea level change remains largely unknown here we show that the canadian arctic archipelago has recently lost 61 7 gigatonnes per year gt yr 1 of ice contributing 0 17 0 02 mm yr 1 to sea level rise our estimates are of regional mass changes for the ice caps and glaciers of the canadian arctic archipelago referring to the years 2004 to 2009 and are based on three independent approaches surface mass budget modelling plus an estimate of ice discharge smb d repeat satellite laser altimetry icesat and repeat satellite gravimetry grace all three approaches show consistent and large mass loss estimates between the periods 2004 2006 and 2007 2009 the rate of mass loss sharply increased from 31 8 gt yr 1 to 92 12 gt yr 1 in direct response to warmer summer temperatures to which rates of ice loss are highly sensitive 64 14 gt yr 1 per 1 k increase the duration of the study is too short to establish a long term trend but for 2007 2009 the increase in the rate of mass loss makes the canadian arctic archipelago the single largest contributor to eustatic sea level rise outside greenland and antarctica

temporal dynamics of suspended sediment transport in a glacierized andean basin abstract suspended sediment transport can affect water quality and aquatic ecosystems and its quantification is of the highest importance for river and watershed management suspended sediment concentration ssc and discharge were measured at two locations in the estero morales a chilean andean stream draining a small basin 27 km2 hosting glacierized areas of about 1 8 km2 approximately half of the suspended sediment yield 470 t year 1 km 2 was transported during the snowmelt period and half during glacier melting the hysteresis patterns between discharge and ssc were calculated for each daily hydrograph and were analysed to shed light on the location and activity of different sediment sources at the basin scale during snowmelt an unlimited supply of fine sediments is provided in the lower and middle part of the basin and hysteresis patterns tend to be clockwise as the peaks in ssc precede the peak of discharge in daily hydrographs instead during glacier melting the source of fine sediments is the proglacial area producing counterclockwise hysteresis it is suggested that the analysis of hysteretic patterns over time provides a simple concept for interpreting variability of location and activity of sediment sources at the basin scale

the suspended sediment dynamics in the inner mongolia reaches of the upper yellow river article i nfo suspended sediment dynamics are still imperfectly understood especially in the upper yellow river where few studies on this issue have been conducted this study analyzed the variability in suspended sediment concentration at different temporal scales within flood monthly seasonal and annual using a dataset up to 49 years long 1954 2002 at toudaoguai station this paper provided insight into the characteristics of suspended sediment transport in the ningxia inner mongolia reaches of the upper yellow river the results show that in a single flood event changes in ssc are not simultaneous with changes in discharge resulting in counterclockwise hysteretic loops clockwise loops or figure eight loops the c q loops and sediment rating curves for different seasons had different characters the diversiform c q loops in the inner mongolia reaches of the upper yellow river may be mainly caused by the sediment inputs from tributaries the differ ent propagation velocity of sediment and water discharge spatial and temporal storage depletion processes of available sediment at annual scale the variations of annual mean discharge and ssc displayed a similar gradually deceasing trend and the relation between water discharge and ssc during 1954 2002 could be de scribed by a cubic polynomial function since the joint operation of liujiaxia and longyangxia reservoirs after 1986 the transport capacity of the upper yellow river has been much reduced

temporal changes in suspended sediment transport in a gullied loess basin the lower chabagou creek on the loess plateau in china suspended sediment dynamics are still imperfectly understood especially in the loess hilly region on the loess plateau with strong temporal variability where few studies heretofore have been conducted using a dataset up to eight years long in the lower chabagou creek the variability in suspended sediment load at different temporal scales within flood variability monthly seasonal and annual is analyzed in this paper the results show that on the within flood scale most of the sediment peaks lag behind peak discharges implying that slope zones are the main sediment source area independent of the occurring sequences of the peaks of sediment and discharge all the events could present an anti clock wise hysteresis loop resulting from the abundant material and the influence of hyperconcentrated flows on suspended sediment concentration at monthly and seasonal scales there is a store release process i e sediment is prepared in winter spring and late autumn and exported in summer and early autumn at the annual scale the high variability in concentration and sediment yield are highly correlated with water yield resulting from the number and magnitude of floods recorded yearly and almost all the suspended load is transported during these events copyright c 2008 john wiley sons ltd

melt regimes stratigraphy flow dynamics and glaciochemistry of three glaciers in the alaska range we used ground penetrating radar gpr gps and glaciochemistry to evaluate melt regimes and ice depths important variables for mass balance and ice volume studies of upper yentna glacier upper kahiltna glacier and the mount hunter ice divide alaska we show the wet percolation and dry snow zones located below 2700ma s l at 2700 to 3900ma s l and above 3900ma s l respectively we successfully imaged glacier ice depths upwards of 480m using 40 100mhz gpr frequencies this depth is nearly double previous depth measurements reached using mid frequency gpr systems on temperate glaciers few holocene length climate records are available in alaska hence we also assess stratigraphy and flow dynamics at each study site as a potential ice core location ice layers in shallow firn cores and attenuated glaciochemical signals or lacking strata in gpr profiles collected on upper yentna glacier suggest that regions below 2800ma s l are inappropriate for paleoclimate studies because of chemical diffusion through melt flow complexities on kahiltna glacier preclude ice core climate studies minimal signs of melt or deformation and depth age model estimates suggesting 4815years of ice on the mount hunter ice divide 3912ma s l make it a suitable holocene age ice core location

updated estimates of glacier volume changes in the western chugach mountains alaska and a comparison of regional extrapolation methods and 2001 2004 average net balance rates ranged between 3 1 to 0 16 m yr 1 for the tidewater and 1 5 to 0 02 m yr 1 for the nontidewater glaciers we tested several methods for extrapolating these measurements to all the glaciers of the western chugach mountains using a process similar to cross validation predictions of individual glacier changes appear to be difficult probably because of the effects of glacier dynamics which on long multidecadal timescales complicates the response of glaciers to climate in contrast estimates of regional contributions to rising sea level were similar for different methods mainly because the large glaciers whose changes dominated the regional total were among those measured for instance the above sea level net balance rate of columbia glacier 3 1 0 08 km 3 yr 1 water equivalent weq or an equivalent rise in sea level sle of 0 0090 0 0002 mm yr 1 was nearly half of the total regional net balance rate of the western chugach mountain glaciers 7 4 1 1 km 3 yr 1 weq or 0 020 0 003 mm yr 1 sle between 1950 1957 and 2001 2004 columbia glacier is a rapidly retreating tidewater glacier that has lost mass through processes largely independent of climate tidewater glaciers should therefore be treated separately when performing regional extrapolations

the use of hypsometry to indicate long term stability and response of valley glaciers to changes in mass transfer a simple equation is derived relating the net mass balance and hypsometric curves of a steady state valley glacier it is used to examine how valley shape is linked to disparate extents and responses of glaciers subjected to similar climatic conditions examples are given which show that area based indices e g aar for estimating the equilibrium line altitude ela may be subject to a substantial built in variance because they implicitly rely upon similarity of glacier shape and regimen over a region if accurate topographic maps are available the equation may be used to infer the regimen of modern glaciers in the form of a dimensionless ratio of net mass balance gradients alternatively if similar information is available concerning regional glacier regimen disparate extents and responses may be collectively utilized to estimate values of ela or to infer climatic influence taking glacier hypsometry into account

rapid wastage of alaska glaciers and their contribution to rising sea level we have used airborne laser altimetry to estimate volume changes of 67 glaciers in alaska from the mid 1950s to the mid 1990s the average rate of thickness change of these glaciers was 0 52 m year extrapolation to all glaciers in alaska yields an estimated total annual volume change of 52 15 km 3 year water equivalent equivalent to a rise in sea level sle of 0 14 0 04 mm year repeat measurements of 28 glaciers from the mid 1990s to 2000 2001 suggest an increased average rate of thinning 1 8 m year this leads to an extrapolated annual volume loss from alaska glaciers equal to 96 35 km 3 year or 0 27 0 10 mm year sle during the past decade these recent losses are nearly double the estimated annual loss from the entire greenland ice sheet during the same time period and are much higher than previously published loss estimates for alaska glaciers they form the largest glaciological contribution to rising sea level yet measured

fast tidewater glaciers some iceberg calving outlet glaciers flow continuously at speeds normally associated with surging glaciers arid exhibit dramatic instability scenarios related to those suggested for marine ice sheets no temperate tidewater glaciers are known to have floating termini but many polar and subpolar tidewater glaciers do the fast flow of temperate calving glaciers is almost entirely due to basal sliding and appears to be a function of the effective pressure on the bed which may approach zero and the longitudinal back stress on the terminus the terminus boundary condition the calving relation is imperfectly known yet is vital to the dynamics of these glaciers calving relations for grounded tidewater glaciers have been suggested on empirical grounds but have not been rigorously tested the calving relations for floating termini are virtually unknown this together with the imperfect understanding of basal sliding inhibits confidence in our understanding of the stability of these glaciers columbia glacier alaska is an instructive example because observations have been made on the major changes in its geometry calving rate and dynamics that have occurred in less than 10 years the calving flux has increased more rapidly than the glacier flux causing thinning and retreat as a result the ice velocity has increased markedly the short term velocity changes relate to changes in back pressure ice recession tidal changes and the flux of water injected to the bed these results have relevance to the mechanisms of basal sliding glacier surges and the stability of marine ice streams

time scale for adjustment of glaciers to changes in mass balance the length of time tm over which a glacier responds to a prior change in climate is investigated with reference to the linearized theory of kinematic waves and to results from numerical models we show the following tm may in general be estimated by a volume time scale describing the time required for a step change in mass balance to supply the volume difference between the initial and final steady states the factor f in the classical estimate of m l u where i is glacier length and u is terminus velocity has a simple geometrical interpretation ft is the ratio of thickness change averaged over the full length i to the change at the terminus although both u and f relate to dynamic processes local to the terminus zone the ratio f u and therefore tm are insensitive to details of the terminus dynamics in contrast to conclusions derived from some simplified kinematic wave models a more robust estimate of tm independent of terminus dynamics is given by tm h b where h is a thickness scale for the glacier and b is the mass balance rate negative at the terminus we suggest that tm for mountain glaciers can be substantially less than the 1o2 103 years commonly considered to be theoretically expected

altitude variation of glacier mass balance in scandinavia 1 for each of ten glaciers in norway and two in sweden vertical profiles of net balance bn z which are typically published as values at about a dozen altitudes are strongly linear and nearly parallel from year to year separate linear functions fit the bn z from year to year with r2 0 89 over the 12 glaciers a family of parallel lines for each glacier that differ from year to year only by an amount bn constant with altitude has r2 0 85 there is an altitude z on each glacier where the measured balance bn z correlates well with the glacier total bn with r 0 97 over the 12 glaciers a remarkable consequence of this and of the high correlation of bn between many of the glaciers in the region is that measurements on one glacier 1775 meters on hardangerjokulen provide a good estimate of bn at several other glaciers

seasonal controls on sediment delivery in a small coastal plain watershed north carolina usa field measurements of drainage ditch sedimentation and suspended sediment transport were used to construct a simple sediment budget and relate seasonal variations in vegetation and the hydrological characteristics of storms to sediment dynamics in a small agricultural watershed in north carolina results indicate that seasonal variations in crop coverage and vegetation in drainage ditches influence sediment delivery following the harvesting of crops and mowing of drainage ditches in late autumn conditions are favorable to soil erosion and sediment transport through early spring storms need not be very intense or produce large rainfall totals to transport significant sediment loads the maturation of field crops and ditch vegetation in spring produces conditions less conducive to both soil erosion and sediment transport intense summer thunderstorms however are capable of mobilizing and transporting significant amounts of sediment the computed sediment yield of 0 1 mg ha yr probably represents a low estimate that nevertheless is an order of magnitude less than measured ditch storage and more than two orders of magnitude less than regional estimates of soil loss on coastal plain croplands the results show that headwater ditches may be decoupled from slopes so that much of the eroded soil is stored within small watersheds rather than being transported out of the basin