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Groundwater System (groundwater + system)
Selected AbstractsGroundwater Systems and Eco-hydrological Features in the Main Karst Regions of ChinaACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 5 2006LU Yaoru Abstract: Different karst water features and related water resources are present both in southern and northern China. There are over 3,358 well-developed karst ground river systems with total discharges in the dry season of about 420times108 m3 in the main karst regions in the southern part of China. Exploitation rates are only 8,15%. Over 100 larger karst spring systems in the main karst regions of northern China cover a catchment area from 500 km2 to over 4,000 km2, of which the average discharge appears to be from about 1 m3/s to 13 m3/s and the exploitation rates are 70,80%. Six aspects of the eco-hydrological features of some typical karst regions in China comprising water environment, ecological features, materials and structures between parent rock and soil, bio-geological processes and palynological studies (spore-pollen) are discussed. Qualitative evaluation of eco-geology and rocky desertification in the karst regions should be based on the main karst ecological conditions as well as artificial, i.e., man-made impacts. [source] Meltwater discharge through the subglacial bed and its land-forming consequences from numerical experiments in the Polish lowland during the last glaciationEARTH SURFACE PROCESSES AND LANDFORMS, Issue 4 2009Jan A. Piotrowski Abstract Numerical experiments suggest that the last glaciation severely affected the upper lithosphere groundwater system in NW Poland: primarily its flow pattern, velocities and fluxes. We have simulated subglacial groundwater flow in two and three spatial dimensions using finite difference codes for steady-state and transient conditions. The results show how profoundly the ice sheet modifies groundwater pressure heads beneath and some distance beyond the ice margin. All model runs show water discharge at the ice forefield driven by ice-sheet-thickness-modulated, down-ice-decreasing hydraulic heads. In relation to non-glacial times, the transient 3D model shows significant changes in the groundwater flow directions in a regionally extensive aquifer ca. 90 m below the ice,bed interface and up to 40 km in front of the glacier. Comparison with empirical data suggests that, depending on the model run, only between 5 and 24% of the meltwater formed at the ice sole drained through the bed as groundwater. This is consistent with field observations documenting abundant occurrence of tunnel valleys, indicating that the remaining portion of basal meltwater was evacuated through a channelized subglacial drainage system. Groundwater flow simulation suggests that in areas of very low hydraulic conductivity and adverse subglacial slopes water ponding at the ice sole was likely. In these areas the relief shows distinct palaeo-ice lobes, indicating fast ice flow, possibly triggered by the undrained water at the ice,bed interface. Owing to the abundance of low-permeability strata in the bed, the simulated groundwater flow depth is less than ca. 200 m. Copyright © 2009 John Wiley & Sons, Ltd. [source] Riparian influence on hyporheic-zone formation downstream of a small dam in the Blackland Prairie region of TexasHYDROLOGICAL PROCESSES, Issue 2 2007Jacquelyn R. Duke Abstract Small-order streams have highly variable flows that can result in large temporal and spatial variation of the hyporheic zone. Dam construction along these intermittent headwater streams alters downstream flow and influences the hydrologic balance between stream water and the adjacent riparian zone. A 3-year site study was conducted along an impounded second-order stream to determine the water balance between stream, unsaturated zone, groundwater and riparian vegetation. The presence of the upstream impoundment provided near-perennial water flow in the stream channel. The observed woody plant transpiration accounted for 71% of average annual water loss in the site. The overall contribution of stream water via the hyporheic zone to site water balance was 73 cm, or 44% of total inputs. This exceeded both rainfall and upland subsurface contribution to the site. A highly dynamic hyporheic zone was indicated by high water use from woody plants that fluctuated seasonally with stream water levels. We found leaf area development in the canopy layer to be closely coupled with stream and groundwater fluctuations, indicating its usefulness as a potential indicator of site water balance for small dam systems. The net result of upstream impoundment increased riparian vegetation productivity by influencing movement of stream water to storage in the groundwater system. Copyright © 2006 John Wiley & Sons, Ltd. [source] Infiltration and solute transport under a seasonal wetland: bromide tracer experiments in Saskatoon, CanadaHYDROLOGICAL PROCESSES, Issue 11 2004David F. Parsons Abstract In the northern glaciated plain of North America, the duration of surface water in seasonal wetlands is strongly influenced by the rate of infiltration and evaporation. Infiltration also plays important roles in nutrient exchange at the sediment,water interface and groundwater recharge under wetlands. A whole-wetland bromide tracer experiment was conducted in Saskatchewan, Canada to evaluate infiltration and solute transport processes. Bromide concentrations of surface water, groundwater, sediment pore water and plant tissues were monitored as the pond water-level gradually dropped until there was no surface water. Hydraulic head gradients showed strong lateral flow from under the wetland to the treed riparian zone during the growing season. The bromide mass balance analysis showed that in early spring, almost 50% of water loss from the wetland was by infiltration, and it increased to about 70% in summer as plants in and around the wetland started to transpire more actively. The infiltration contributed to recharging the shallow, local groundwater under the wetland, but much of it was taken up by trees without recharging the deeper groundwater system. Emergent plants growing in the wetlands incorporated some bromide, but overall uptake of bromide by vegetation was less than 10% of the amount initially released. After one summer, most of the subsurface bromide was found within 40,80 cm of the soil surface. However, some bromide penetrated as deep as 2,3 m, presumably owing to preferential flow pathways provided by root holes or fractures. Copyright © 2004 Crown in the Right of Canada. Published by John Wiley & Sons, Ltd. [source] Propagation of drought through groundwater,a new approach using linear reservoir theoryHYDROLOGICAL PROCESSES, Issue 15 2003E. Peters Abstract The effect of drought on groundwater heads and discharge is often complex and poorly understood. Therefore the propagation of a drought from groundwater recharge to discharge and the influence of aquifer characteristics on the propagation was analysed by tracking a drought in recharge through a linear reservoir. The recharge was defined as a sinusoid function with a period of 1 year. The decrease in recharge owing to drought was simulated by multiplying the recharge during 1 year with a drought fraction between 0 and 1, which represents a decrease in the recharge of 100 to 0%, respectively. The droughts were identified using the threshold level approach, with a threshold that is constant in time. For this case analytical formulations were derived, which express the drought duration and deficit in the groundwater discharge in terms of the decrease in recharge, the reservoir coefficient that characterizes aquifer properties and the height of the threshold level. The results showed that the delay in the groundwater system caused a shift of the main part of the decrease in recharge from the high-flow to the low-flow period. This resulted in an increase in drought deficit for discharge compared with the drought deficit for recharge. Also the development of multiyear droughts caused an increase in drought deficit. The attenuation in the groundwater system caused a decrease in drought deficit. In most cases the net effect of these processes was an increase of drought deficit as a result of the propagation through groundwater. Only for small droughts the deficit decreased from recharge to discharge. The amount of increase or decrease depends on the reservoir coefficient and the severity of the drought. Under most conditions a maximum in the drought deficit occurred for a reservoir coefficient of around 200 days. Copyright © 2003 John Wiley & Sons, Ltd. [source] Density-dependent surface water,groundwater interaction and nutrient discharge in the Swan,Canning EstuaryHYDROLOGICAL PROCESSES, Issue 13 2001Anthony J. Smith Abstract Salinity in the Swan,Canning Estuary, Western Australia, varies seasonally from freshwater conditions in winter up to the salinity of seawater in summer. Field observations show that the resulting seasonal density contrasts between the estuary and the adjacent fresh groundwater system are sufficient to drive mixed-convection cells that give rise to circulation of river water in the aquifer. In this study, we examine the role of steady density-driven convection as a mechanism that contributes to the exchange of dissolved nutrients, particularly ammonium, between the Swan,Canning Estuary and the local groundwater system. We present results from two-dimensional (section) and three-dimensional density-coupled flow and mass transport modelling, in comparison with Glover's abrupt-interface solution for saltwater intrusion. The modelling is focused on developing an understanding of the physical processes that influence the long-term or mean convective behaviour of groundwater beneath the estuary. It is shown that the convective stability depends fundamentally on the interplay between two factors: (1) the downward destabilizing buoyancy effect of density contrasts between the estuary and aquifer; and (2) the upward stabilizing influence of regional groundwater discharge. The structure of convection cells beneath the estuary and recirculation rates of estuary water within the groundwater system are shown to be related to a flow-modified Rayleigh number that depends critically on the aquifer anisotropy and estuary meander pattern. The recirculation of estuary water by these mechanisms is responsible for transport of high concentrations of ammonium, observed in pore fluids in the estuary bed sediments, into groundwater and its eventual return to the estuary. Copyright © 2001 John Wiley & Sons, Ltd. [source] Capitalized amenity value of urban wetlands: a hedonic property price approach to urban wetlands in Perth, Western Australia,AUSTRALIAN JOURNAL OF AGRICULTURAL & RESOURCE ECONOMICS, Issue 4 2009Sorada Tapsuwan Up to 60 per cent of potable water supplied to Perth, Western Australia, is extracted from the groundwater system that lies below the northern part of the metropolitan area. Many of the urban wetlands are groundwater-dependent and excessive groundwater extraction and climate change have resulted in a decline in water levels in the wetlands. In order to inform decisions on conserving existing urban wetlands, it is beneficial to be able to estimate the economic value of the urban wetlands. Applying the Hedonic Property Price approach to value urban wetlands, we found that distance to the nearest wetland and the number of wetlands within 1.5 km of a property significantly influence house sales price. For a property that is 943 m away from the nearest wetland, which is the average distance to the wetland in this study, reducing the wetland distance by 1 m will increase the property price by AU$42.40. Similarly, the existence of an additional wetland within 1.5 km of the property will increase the sales price by AU$6976. For a randomly selected wetland, assuming a 20 ha isolated circular wetland surrounded by uniform density housing, the total sales premium to surrounding properties was estimated to be around AU$140 million (AU$40 million and AU$230 million). [source] Hydrogeological Characteristics of a Karst Mountainous Catchment in the Northwest of VietnamACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2001V. T. TAM Abstract This paper presents a preliminary assessment of the hydrogeological characteristics of a karst mountainous catchment, the Suoi Muoi River catchment, in the northwest of Vietnam. The catchment is located at 600,700 m a.s.l. and covers an area of 284 km. Exposed limestone occupies 32% of the total catchment area. Various types of assessments have been carried out, including geological and hydrogeological field surveys, cave surveys, dye-tracer tests, meteorological and surface water monitoring. Geological studies and cave surveys have identified the most important active cave/conduit systems within the catchment. Although these data are essential, they are insufficient to make a comprehensive appraisal of the hydrologic nature of the catchment under interest. An attempt was made to calculate a global water balance of the catchment, based on short-term (15 months) meteorological and streamflow records. The results show that, despite the existence of a number of substantial cavern conduit systems, the groundwater system of the catchment is governed by the fracture/fissure matrix. The cavern conduit systems only collect groundwater from the adjacent fracture matrix and/or connect topographically isolated surface watercourses. The groundwater storage of the cavern conduit systems appears to be regionally insignificant in comparison with the governed fracture matrix groundwater system. [source] Assessment of high density of onsite wastewater treatment systems on a shallow groundwater coastal aquifer using PCAENVIRONMETRICS, Issue 3 2005Steven Carroll Abstract Onsite wastewater treatment systems are common throughout the world, including Australia, with approximately 17% of the Australian population relying on these systems to treat and ultimately dispose of wastewater. Systems which are properly sited, designed and managed are an effective way of providing the necessary treatment of wastewater. However, incidence of onsite system failure is common, and this is further compounded in areas where high densities of systems are established. The density of systems is not appropriately assessed in the siting and design stage. Various factors, such as site and soil characteristics and climate, can influence the treatment efficiency, and this is more critical in high density areas. Principal component analysis was used for assessing chemical and microbiological data from shallow groundwater below a high density of onsite treatment systems. The results of this study confirmed that high system densities can significantly impact shallow groundwater systems. Additionally, changes in spatial and climatic conditions, as well as the type of onsite system, can also influence the quality of groundwater. Copyright © 2004 John Wiley & Sons, Ltd. [source] Comparison of routine metabolic rates of the stygobite, Gammarus acherondytes (Amphipoda: Gammaridae) and the stygophile, Gammarus troglophilusFRESHWATER BIOLOGY, Issue 6 2006FRANK M. WILHELM Summary 1. Reduced metabolic rate among cave organisms compared with surface species has long been suggested as an adaptation to food shortage in cave environments. However, comparisons of metabolic rates between species have not often included closely related surface and cave species. By measuring metabolic rate across three seasons and over a range of body sizes, we examined the hypothesis that the routine metabolic rate of Gammarus acherondytes, a federally listed stygobitic amphipod, is lower than that of the closely related stygophilic Gammarus troglophilus. To determine if human activities increased the supply of organic matter to caves, we also examined the relationship between residential development and bacterial contamination in water wells. 2. For G. acherondytes, the slope of the overall relationship between oxygen consumption and body dry mass did not differ from zero and did not vary seasonally, whereas for G. troglophilus it was positive and higher in summer than in winter and spring. These results provide insights into a potential novel metabolic adaptation among stygobites. Higher metabolic rate in young G. acherondytes would allow efficient use of typically transient energy sources and a low metabolic rate at larger body sizes would increase survival through periods of food scarcity. 3. The number of wells with faecal coliform contamination was weakly but positively correlated with the number of residential building permits, indicating that surface land-use changes probably increase the availability of energy in groundwater systems inhabited by G. acherondytes. This may give stygophilic animals, with higher metabolic rates, a competitive advantage in the caves, thus reducing the abundance of stygobites such as G. acherondytes. [source] Environmental isotopic and hydrochemical characteristics of groundwater systems in Daying and Qicun geothermal fields, Xinzhou Basin, Shanxi, ChinaHYDROLOGICAL PROCESSES, Issue 22 2010Dongmei Han Abstract The conceptual hydrogeological model of the low to medium temperature Daying and Qicun geothermal fields has been proposed, based on hydrochemical characteristics and isotopic compositions. The two geothermal fields are located in the Xinzhou basin of Shanxi, China and exhibit similarities in their broad-scale flow patterns. Geothermal water is derived from the regional groundwater flow system of the basin and is characterized by Cl·SO4 -Na type. Thermal water is hydrochemically distinct from cold groundwater having higher total dissolved solids (TDS) (>0·8 g/l) and Sr contents, but relatively low Ca, Mg and HCO3 contents. Most shallow groundwater belongs to local flow systems which are subject to evaporation and mixing with irrigation returns. The groundwater residence times estimated by tritium and 14C activities indicate that deep non-thermal groundwater (130,160 m) in the Daying region range from modern (post-1950s) in the piedmont area to more than 9·4 ka BP (Before Present) in the downriver area and imply that this water belong to an intermediate flow system. Thermal water in the two geothermal fields contains no detectable active 14C, indicating long residence times (>50 ka), consistent with this water being part of a large regional flow system. The mean recharge elevation estimated by using the obtained relationship Altitude (m) = , 23·8 × ,2H (, ) , 121·3, is 1980 and 1880 m for the Daying and Qicun geothermal fields, respectively. The annual infiltration rates in the Daying and Qicun geothermal fields can be estimated to be 9029 × 103 and 4107 × 103 m3/a, respectively. The variable 86Sr/87Sr values in the thermal and non-thermal groundwater in the two fields reflect different lithologies encountered along the flow path(s) and possibly different extents of water-rock interaction. Based on the analysis of groundwater flow systems in the two geothermal fields, hydrogeochemical inverse modelling was performed to indicate the possible water-rock interaction processes that occur under different scenarios. Copyright © 2010 John Wiley & Sons, Ltd. [source] Aquatic Microbial Ecology: Water Desert, Microcosm, Ecosystem.INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 4-5 2008What's Next? Abstract Aquatic microbial ecology aims at nothing less than explaining the world from "ecological scratch". It develops theories, concepts and models about the small and invisible living world that is at the bottom of every macroscopic aquatic system. In this paper we propose to look at the development of Aquatic Microbial Ecology as a reiteration of classical (eukaryotic) limnology and oceanography. This was conceptualized moving historically from the so-called water desert to microcosm to ecosystem. Each of these concepts characterizes a particular historical field of knowledge that embraces also practices and theories about living beings in aquatic environments. Concerning the question of "who is there", however, Aquatic Microbial Ecology historically developed in reverse order. Repetition, reiteration and replication notwithstanding, Aquatic Microbial Ecology has contributed new ideas, theories and methods to the whole field of ecology as well as to microbiology. The disciplining of Aquatic Microbial Ecology happened in the larger field of plankton biology, and it is still attached to this biological domain, even conceiving of itself very self-consciously as a discipline of its own. Today, Aquatic Microbial Ecology as a discipline is much broader than plankton ecology ever was, for it includes not only oceans and freshwaters but also benthic, interstitial and groundwater systems. The success of Aquatic Microbial Ecology is expressed by its influence on other fields in ecology. The challenge is to further develop its theoretical and methodological features while at the same time contributing to current pressing problems such as climate change or the management of global water resources. And then it may not be fanciful to suppose that even in the year nineteen hundred and nineteen a great number of minds are still only partially lit up by the cold light of knowledge. It is the most capricious illuminant. They are still apt to ruminate, without an overpowering bias to the truth, whether a kingfisher's body shows which way the wind blows; whether an ostrich digests iron; whether owls and ravens herald ill-fortune; and the spilling of salt bad luck; what the tingling of ears forebodes, and even to toy pleasantly with more curious speculations as to the joints of elephants and the politics of storks, which came within the province of the more fertile and better-informed brain of the author (1919) Virginia Woolf from the essay "Reading", In: Leonard Woolf (ed.), 1950: The Captain's Death Bed and Other Essays, , London: Hogarth Press, p. 157. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Upscaling water savings from farm to irrigation system level using GIS-based agro-hydrological modelling,IRRIGATION AND DRAINAGE, Issue 1 2007Shahbaz Khan simulation d'irrigation; extrapolation; efficacité d'utilisation de l'eau; économie de l'eau Abstract Irrigation continues to be the main water user on a global scale despite the increase in water use by sectors other than agriculture. More efficient water application technologies and water management practices are ways of realising potential water savings, thus moderating the negative impacts of higher water use on farm incomes and environmental impact on rivers and groundwater systems. This paper describes an integrated approach of agro-hydrological modelling for determining potential water savings achievable by adopting high-tech irrigation technologies at farm level and application of GIS techniques to upscale those benefits at the regional irrigation system level. The SWAP (Soil,Water,Atmosphere,Plant) model was used for the simulation of water use at the farm level. The results are promising, as the potential water saving ranges from 0.1 to 2.2,ML,ha,1 (10,220,mm) for different broad-acre crops, 1.0 to 2.0,ML,ha,1 (100,200,mm) in sprinkler and 2.0 to 3.0,ML,ha,1 (200,300,mm) in drip irrigation for citrus, 1.0 to 1.5,ML,ha,1 (100,150,mm) in sprinkler and up to 4.0,ML,ha,1 (400,mm) in drip irrigation for vineyards and 0.5 to 1.0,ML,ha,1 for vegetables (50,100,mm). SWAP simulations show crop water saving potential of 7% for maize, 15% for soybean, 17% for wheat, 35% for barley, 17% for sunflower and 38% for fababean from the current water use statistics in Australia. Spatial analysis in GIS environment is carried out to investigate the spatial variations of water use for a particular crop under different depths to water table and varying soil types. Maps of water need for all broad-acre crops are drawn and pixel-to-pixel comparison is performed to determine the water saving potential per unit area. The upscaling approach shows that considerable water amounts could be saved both in Murrumbidgee Irrigation Area (MIA) and Coleambally Irrigation Area (CIA) with potential water saving of 36 to 95,GL (MCM) in MIA and 42 to 72,GL (MCM) in CIA. Copyright © 2007 John Wiley & Sons, Ltd. L'irrigation reste l'usage principal de l'eau à l'échelle mondiale en dépit de l'augmentation des volumes utilisés par les secteurs autres que l'agriculture. L'amélioration des techniques d'irrigation et des procédures de gestion de l'eau permet de réaliser des économies d'eau potentielles, modérant ainsi les impacts négatifs d'une surconsommation d'eau sur les revenus agricoles et ses incidences sur l'environnement des cours d'eau et des aquifères. Cet article décrit comment un modèle agro-hydrologique intégré peut déterminer les économies d'eau réalisables grâce à l'adoption de technologies de pointe dans l'irrigation au niveau de l'exploitation agricole et à l'application des techniques de SIG à l'extension de ces avantages au niveau d'un système régional d'irrigation. Le modèle SWAP (Sol-Eau-Atmosphère-Plante) a été employé pour simuler l'utilisation de l'eau au niveau de l'exploitation. Les résultats sont prometteurs car l'économie d'eau potentielle va de 100 à 2 200 m3/ha (10 à 220 millimètres) pour différentes cultures de plein champ, de 1 000 à 2 000 m3/ha (100 à 200 millimètres) en aspersion et de 2 000 à 3 000 m3/ha (200 à 300 millimètres) en goutte à goutte sur des citronniers, de 1 000 à 1 500 m3/ha (100 à 150 millimètres) en aspersion et jusqu'à 4 000 m3/ha (400 millimètres) en goutte à goutte sur de la vigne, et de 500 à 1 000 m3/ha pour des légumes (50 à 100 millimètres). Les simulations de SWAP à partir de données statistiques australiennes courantes montrent un potentiel d'économie d'eau de 7% pour le maïs, 15% pour le soja, 17% pour le blé, 35% pour l'orge, 17% pour le tournesol et 38% pour les fèves. Une analyse par SIG permet d'étudier les variations spatiales de l'utilisation de l'eau pour une récolte particulière selon la profondeur de la nappe et le type de sol. Les besoins en eau de toutes les cultures de plein champ sont cartographiés et le potentiel d'économie d'eau par unité de surface est estimé pixel par pixel. L'extrapolation des résultats montre que des volumes d'eau considérables pourraient être économisés dans les zones irriguées de Murrumbidgee (MIA, économie potentielle de 36 à 95 millions de m3) et de Coleambally (CIA, économie potentielle de 42 à 72 m3). Copyright © 2007 John Wiley & Sons, Ltd. [source] Distribution of ,34S and ,18O in SO2,4 in Groundwater from the Ordos Cretaceous Groundwater Basin and Geological ImplicationsACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 2 2010Yuncheng YANG Abstract: The Ordos Cretaceous Groundwater Basin, located in an arid-semiarid area in northwestern China, is a large-style groundwater basin. SO2,4 is one of the major harmful components in groundwater. Dissolved SO2,4 concentrations, and ,34S-SO2,4 and ,18O-SO2,4 in groundwater from 14 boreholes and in gypsum from aquifer were analyzed. Results show that SO2,4 in shallow groundwaters originates from precipitation, sulfide oxidation, and dissolution of stratum sulphate, with a big range of ,34S values, from ,10.7, to 9.2,, and addition of SO2,4 in deep groundwater results from dissolution of stratum sulphate, with bigger ,34S values, from 7.8, to 18.5,, compared with those in shallow groundwater. This research also indicates that three types of sulphate are present in the strata, and characterized by high ,34S values and high ,18O values-style, high ,34S values and middle ,18O values-style, middle ,34S values and low ,18O values-style, respectively. The ,34S-SO2,4 and ,18O-SO2,4 in groundwater have a good perspective for application in distinguishing different groundwater systems and determining groundwater circulation and evolution in this area. [source] | ||||||||||||||||