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1.
High groundwater salinity has become a major concern in the arid alluvial plain of the Dunhuang Basin in northwestern China because it poses a significant challenge to water resource management. Isotopic and geochemical analyses were conducted on 55 water samples from springs, boreholes and surface water to identify potential sources of groundwater salinity and analyse the processes that control increasing salinity. The total dissolved solid (TDS) content in the groundwater ranged from 400 to 41 000 mg/l, and high TDS values were commonly associated with shallow water tables and flow‐through and discharge zones in unconfined aquifers. Various groundwater contributions from rainwater, agricultural irrigation, river water infiltration and lateral inflows from mountains were identified by major ions and δD and δ18O. In general, HCO3? and SO42? were the dominant anions in groundwater with a salinity of <2500 mg/l, whereas Cl? and SO42? were the dominant anions in groundwater with a salinity of >2500 mg/l. The major ion concentrations indicated that mineral weathering, including carbonate and evaporite dissolution, primarily affected groundwater salinity in recharge areas. Evapotranspiration controlled the major ion concentration evolution and salinity distribution in the unconfined groundwaters in the flow‐through and discharge areas, although it had a limited effect on groundwater in the recharge areas and confined aquifers. Agricultural irrigation increased the water table and enhanced evapotranspiration in the oasis areas of the basin. TDS and Cl became more concentrated, but H and O isotopes were not enriched in the irrigation district, indicating that transpiration dominated the increasing salinity. For other places in the basin, as indicated by TDS, Cl, δD and δ18O characteristics, evaporation, transpiration and water–rock interactions dominated at different hydrogeological zones, depending on the plant coverage and hydrogeological conditions. Groundwater ages of 3H, and δD and δ18O compositions and distributions suggest that most of the groundwaters in Dunhuang Basin have a paleometeoric origin and experienced a long residence time. These results can contribute to groundwater management and future water allocation programmes in the Dunhuang Basin. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

2.
With the increasing demand for water resources, the utilization of marginal water resources of poor-quality has become a focus of attention. The brackish water developed in the Loess Plateau is not only salty but also famous for its ‘bitterness’. In the present work, multi-isotope analysis (Sr, B) was combined with geochemical analysis to gain insight into the hydrogeochemical evolution and formation mechanisms of brackish water. These results demonstrate that groundwater in the headwater is influenced by carbonate weathering. After the confluence of several tributaries in the headwater, the total dissolved solids (TDS) of water is significantly increased. The dissolution of evaporates is shown to be the main source of salinity in brackish water, which also greatly affects the strontium isotopic composition of water. This includes the dissolution of Mg-rich minerals, which is the main cause of the bitterness. Furthermore, the release of calcium from the dissolution of gypsum may induce calcite precipitation and incongruent dissolution of dolomite, which also contributes to the enrichment of magnesium. The highly fractionated boron isotopic values observed in the upstream groundwater were explained by the absorption with clay minerals. The inflow of brackish groundwater is the source of river water. Then evaporation further aggravates the salinization of river water, with water quality evolving to saline conditions in the lower reach. When the river reaches the valley plain, the 87Sr/86Sr ratios decreases significantly, which is primarily related to erosion of the riverbanks during runoff. These results indicate that water resource sustainability could be enhanced by directing focus to mitigating salinization in the source area of the catchment.  相似文献   

3.
Rainwater, groundwater and soil-water samples were analysed to assess groundwater geochemistry and the origin of salinity in the Ochi-Narkwa basin of the Central Region of Ghana. The samples were measured for major ions and stable isotopes (δ18O, δ2H and δ13C). The Cl? content in rainwater decreased with distance from the coast. The major hydrochemical facies were Na-Cl for the shallow groundwaters and Ca-Mg-HCO3, Na-Cl and Ca-Mg-Cl-SO4 for the deep groundwaters. Groundwater salinization is caused largely by halite dissolution and to a minor extent by silicate weathering and seawater intrusion. Stable isotope composition of the groundwaters followed a slope of 3.44, suggesting a mixing line. Chloride profiles in the soil zone revealed the existence of salt crusts, which support halite dissolution in the study area. A conceptual flow model developed to explain the mechanism of salinization showed principal groundwater flow in the NW–SE direction.
EDITOR D. Koutsoyiannis

ASSOCIATE EDITOR K. Heal  相似文献   

4.
Flow regulation and water diversion for irrigation have considerably impacted the exchange of surface water between the Murray River and its floodplains. However, the way in which river regulation has impacted groundwater–surface water interactions is not completely understood, especially in regards to the salinization and accompanying vegetation dieback currently occurring in many of the floodplains. Groundwater–surface water interactions were studied over a 2 year period in the riparian area of a large floodplain (Hattah–Kulkyne, Victoria) using a combination of piezometric surface monitoring and environmental tracers (Cl−, δ2H, and δ18O). Despite being located in a local and regional groundwater discharge zone, the Murray River is a losing stream under low flow conditions at Hattah–Kulkyne. The discharge zone for local groundwater, regional groundwater and bank recharge is in the floodplain within ∼1 km of the river and is probably driven by high rates of transpiration by the riparian Eucalyptus camaldulensis woodland. Environmental tracers data suggest that the origin of groundwater is principally bank recharge in the riparian zone and a combination of diffuse rainfall recharge and localized floodwater recharge elsewhere in the floodplain. Although the Murray River was losing under low flows, bank discharge occurred during some flood recession periods. The way in which the water table responded to changes in river level was a function of the type of stream bank present, with point bars providing a better connection to the alluvial aquifer than the more common clay‐lined banks. Understanding the spatial variability in the hydraulic connection with the river channel and in vertical recharge following inundations will be critical to design effective salinity remediation strategies for large semi‐arid floodplains. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

5.
Chloride is a major anion in soil water and its concentration rises essentially as a function of evapotranspiration. Compared to herbaceous vegetation, high transpiration rates are measured for isolated trees, shelterbelts or hedgerows. This article deals with the influence of a tree hedge on the soil and groundwater Cl? concentrations and the possibility of using Cl? as an indicator of transpiration and water movements near the tree rows. Cl? concentrations were measured over 1 year at different depths in the unsaturated zone and in the groundwater along a transect intersecting a bottomland oak hedge. We observed a strong spatial heterogeneity of Cl? concentrations, with very high values up to 2 g l?1 in the unsaturated zone and 1·2 g l?1 in the upper part of the groundwater. This contrasts with the low and homogeneous concentrations (60–70 mg l?1) in the deeper part of the groundwater. Cl? accumulation in the unsaturated zone at the end of the vegetation season allows us to identify the active root zone extension of trees. In winter, upslope of the tree row, downwards leaching partly renews the soil solution in the root zone, while the slow water movement under the trees or farther downslope results in Cl? accumulation and leads to a salinization of the soil and groundwater. This salinization is of the same order as experimental conditions produce negative effects on oak seedlings. The measurement of Cl? concentrations in the unsaturated zone under tree rows at the end of the vegetation season would indicate whether certain topographic, pedological or climatic conditions are likely to favour a strong salinization of the soil, as observed in the present study. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

6.
The isotopic chemistry of alluvial groundwaters from two adjacent valleys are described and hydrological processes within related aquifers are identified as evidenced by oxygen-18, deuterium, tritium and chloride data. A plot of δ18O against δD values reveals isotopic enrichment of the groundwater by the recycling of spray irrigation water. A plot of tritium versus chloride concentrations displays separate linear correlations for alluvial groundwaters within the two valleys. The salinity has a common source, therefore the separate correlations are interpreted as the past transfer of low salinity groundwater from the alluvial aquifers in one valley to the underlying sandstone aquifers.  相似文献   

7.
We evaluated sources and pathways of groundwater recharge for a heterogeneous alluvial aquifer beneath an agricultural field, based on multi‐level monitoring of hydrochemistry and environmental isotopes of a riverside groundwater system at Buyeo, Korea. Two distinct groundwater zones were identified with depth: (1) a shallow oxic groundwater zone, characterized by elevated concentrations of NO3? and (2) a deeper (>10–14 m from the ground surface) sub‐oxic groundwater zone with high concentrations of dissolved Fe, silica, and HCO3?, but little nitrate. The change of redox zones occurred at a depth where the aquifer sediments change from an upper sandy stratum to a silty stratum with mud caps. The δ18O and δ2H values of groundwater were also different between the two zones. Hydrochemical and δ18O? δ2H data of oxic groundwater are similar to those of soil water. This illustrates that recharge of oxic groundwater mainly occurs through direct infiltration of rain and irrigation water in the sandy soil area where vegetable cropping with abundant fertilizer use is predominant. Oxic groundwater is therefore severely contaminated by agrochemical pollutants such as nitrate. In contrast, deeper sub‐oxic groundwater contains only small amounts of dissolved oxygen (DO) and NO3?. The 3H contents and elevated silica concentrations in sub‐oxic groundwater indicate a somewhat longer mean residence time of groundwater within this part of the aquifer. Sub‐oxic groundwater was also characterized by higher δ18O and δ2H values and lower d‐excess values, indicating significant evaporation during recharge. We suggest that recharge of sub‐oxic groundwater occurs in the areas of paddy rice fields where standing irrigation and rain water are affected by strong evaporation, and that reducing conditions develop during subsequent sub‐surface infiltration. This study illustrates the existence of two groundwater bodies with different recharge processes within an alluvial aquifer. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

8.
Accurate estimation of groundwater recharge (GR) and evapotranspiration (ET) are essential for sustainable management of groundwater resources, especially in arid and semi-arid regions. In the Manas River Basin (MRB), water shortage is the main factor restricting sustainable development of irrigated agriculture, which relies heavily on groundwater. Film-mulched drip irrigation significantly changes the pattern and dominant processes of water flow in the unsaturated zone, which increases the difficulty of GR and ET estimation. To better estimate GR and ET under film-mulched drip irrigation in the MRB, bromide tracer tests and soil lithologic investigation were conducted at 12 representative sites. A one-dimensional variably saturated flow model (HYDRUS-1D) was calibrated at each site using soil evaporation data inferred from the bromide tracer tests. The results showed that average annual soil evaporation in uncultivated lands calculated from bromide trace tests was 25.55 mm. The annual GR ranged from 5.5 to 37.0 mm under film-mulched drip irrigation. The annual ET ranged from 507.0 to 747.1 mm, with soil evaporation between 35.7 and 117.0 mm and transpiration between 460.9 and 642.3 mm. Soil evaporation represented 7% to 16% of the total ET and more than 70% of precipitation and irrigation water was used by cotton plants. Spatial variations of soil lithology, water table depth and initial soil water content led to the spatial differences of GR and ET in the MRB. Our study indicated that bromide tracer tests are useful for inferring ET in the arid and semi-arid oases. The combination of bromide tracer tests and HYDRUS-1D enhances reliability for estimation of GR and ET under film-mulched drip irrigation in the MRB and shows promise for other similar arid inland basins around the world.  相似文献   

9.
Based on stable isotopes in stream water, groundwater, and meltwater in the Kaidu River Basin, NW China, we estimated the evaporation enrichment of stable oxygen isotopes in different types of water and separated the contribution of each streamflow component in river run‐off. Our results indicated that δ18O and δ2H in stream water did not vary with altitude regularly but with seasons, with low concentrations in spring and high concentrations in summer. However, the seasonal variations of δ18O and δ2H in groundwater were not as obvious. The mean evaporation enrichment was between 26% and 44% for δ18O. Of the various water types under investigation, we found glaciers were influenced the most, showing an evaporation enrichment of 44%, followed by oasis groundwater (37%), stream water (36%), and mountain groundwater (26%). Overall, meltwater and groundwater were the predominant streamflow components, with their contributions were governed by temperature, and varied both temporally and specially. In the oasis region, groundwater was the predominant contributor (64% in spring, 50% in summer, and 66% in autumn), whereas in the mountains, groundwater was the dominant in spring (53%) and autumn (51%), and meltwater contributed the most in summer (52%). Precipitation contributed less than 15% to the streamflow.  相似文献   

10.
High‐salinity paleowater from low‐permeability aquitards in coastal areas can be a major threat to groundwater resources; however, such water has rarely been studied. The chemical and isotopic compositions of porewater extracted from a 200‐m‐thick Quaternary sedimentary sequence in the western coastal plain of Bohai Bay, China, were analyzed to investigate the salinity origin and chemical evolution of porewater in aquitards. Porewater samples derived at depths shallower than 32 m are characterized by Cl‐Na type saline water (total dissolved solids [TDS], 10.9–84.3 g/L), whereas those at depths greater than 32 m comprise Cl·SO4‐Na type brackish water (TDS, 2.2–6.3 g/L). Saline porewater is interpreted as evaporated seawater prior to halite saturation, as evidenced by Cl‐Br relationships. Although substantial dilution of saline porewater with meteoric water is supported by a wider Cl? range and δ2H‐δ18O covariance, the original marine waters were not completely flushed out. The deeper brackish porewater is determined to be a mixture of fresher porewater and brine groundwater and had a component of old brine of less than 10%, as indicated by a mixing model defined using δ2H and Cl? tracers. Porewater δ2H‐δ18O relationships and negative deuterium excess ranging from ?25.9‰ to ?2.9‰ indicate the existence of an arid climate since Late Pleistocene in Tianjin Plain. The aquitard porewaters were chemically modified through water‐rock interactions due to the long residence time.  相似文献   

11.
Recharge areas of the Guarani Aquifer System (GAS) are particularly sensitive and vulnerable to climate variability; therefore, the understanding of infiltration mechanisms for aquifer recharge and surface run‐off generation represent a relevant issue for water resources management in the southeastern portion of the Brazilian territory, particularly in the Jacaré‐Pepira River watershed. The main purpose of this study is to understand the interactions between precipitation, surface water, and groundwater using stable isotopes during the strong 2014–2016 El Niño Southern Oscillation event. The large variation in the isotopic composition of precipitation (from ?9.26‰ to +0.02‰ for δ18O and from ?63.3‰ to +17.6‰ for δ2H), mainly associated with regional climatic features, was not reflected in the isotopic composition of surface water (from ?7.84‰ to ?5.83‰ for δ18O and from ?49.7‰ to +33.6‰ for δ2H), mainly due to the monthly sampling frequency, and groundwater (from ?7.04‰ to ?7.76‰ for δ18O and from ?49.5‰ to ?44.7‰ for δ2H), which exhibited less variation throughout the year. However, variations in deuterium excess (d‐excess) in groundwater and surface water suggest the occurrence of strong secondary evaporation during the infiltration process, corresponding with groundwater level recovery. Similar isotopic composition in groundwater and surface water, as well as the same temporal variations in d‐excess and line‐conditioned excess denote the strong connectivity between these two reservoirs during baseflow recession periods. Isotopic mass balance modelling and hydrograph separation estimate that the groundwater contribution varied between 70% and 80%, however, during peak flows, the isotopic mass balance tends to overestimate the groundwater contribution when compared with the other hydrograph separation methods. Our findings indicate that the application of isotopic mass balance methods for ungauged rivers draining large groundwater reservoirs, such as the GAS outcrop, could provide a powerful tool for hydrological studies in the future, helping in the identification of flow contributions to river discharge draining these areas.  相似文献   

12.
We used hydrochemistry and environmental isotope data (δ18O, δD, tritium, and 14C) to investigate the characteristics of river water, groundwater, and groundwater recharge in China's Heihe River basin. The river water and groundwater could be characterized as Ca2+? Mg2+? HCO3?? SO42? and Na+? Mg2+? SO42?? Cl? types, respectively. Hydrogeochemical modelling using PHREEQC software revealed that the main hydrogeochemical processes are dissolution (except for gypsum and anhydrite) along groundwater flow paths from the upper to middle Heihe reaches. Towards the lower reaches, dolomite and calcite tend to precipitate. The isotopic data for most of the river water and groundwater lie on the global meteoric water line (GMWL) or between the GMWL and the meteoric water line in northwestern China, indicating weak evaporation. No direct relationship existed between recharge and discharge of groundwater in the middle and lower reaches based on the isotope ratios, d‐excess, and 14C values. On the basis of tritium in precipitation and by adopting an exponential piston‐flow model, we evaluated the mean residence time of shallow groundwater with high tritium activities, which was around 50 years (a). Furthermore, based on the several popular models, it is calculated that the deep groundwaters in piedmont alluvial fan zone of the middle reaches and in southern part of the lower reaches are modern water, whereas the deep groundwaters in the edge of the middle reaches and around Juyan Lake in the lower reaches of Heihe river basin are old water. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

13.
Chahardouly basin is located in the western part of Iran and is characterized by semi‐arid climatic conditions and scarcity in water resources. The main aquifer systems are developed within alluvial deposits. The availability of groundwater is rather erratic owing to the occurrence of hard rock formation and a saline zone in some parts of the area. The aquifer systems of the area show signs of depletion, which have taken place in recent years due to a decline in water levels. Groundwater samples collected from shallow and deep wells were analysed to examine the quality characteristics of groundwater. The major ion chemistry of groundwater is dominated by Ca2+ and HCO3?, while higher values of total dissolved solids (TDS) in groundwater are associated with high concentrations of all major ions. An increase in salinity is recorded in the down‐gradient part of the basin. The occurrence of saline groundwater, as witnessed by the high electrical conductivity (EC), may be attributed to the long residence time of water and the dissolution of minerals, as well as evaporation of rainfall and irrigation return flow. Based on SAR values and sodium content (%Na), salinity appears to be responsible for the poor groundwater quality, rendering most of the samples not suitable for irrigation use. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

14.
Increasing groundwater salinity and depletion of the aquifers are major concerns in the UAE. Isotopes of oxygen, hydrogen, and carbon concentrations in groundwater were used to estimate evaporation loss using the isotopes of oxygen and hydrogen, and using a carbon isotope to trace inorganic carbon cycling in two main aquifers in the eastern part of the United Arab Emirates. The δD‐δ18O of groundwater samples plotted on a line given by: δD = 4 δ18O + 4 ·4 (r2 = 0·4). In comparison, the local meteoric water line (LMWL) has been defined by the line: δD = 8 δ18O + 15. In order to better understand the system investigated, samples were separated into two groups based on the δD‐δ18O relationship. These are (1) samples that plot above the LMWL (δD = 6·1 δ18O + 12·4, r2 = 0·8) and which are located predominantly in the north of the study area, and (2) samples that plot below the LMWL (δD = 5·6 δ18O + 6·2, r2 = 0·8) and which are mostly distributed in the south. Slopes for both the groups are similar and lower than that for LMWL indicating potential evaporation of recharging water. However, the y‐intercept, which differs between the two groups, suggests evaporation of return flow and evapotranspiration in the unsaturated zone to be more significant in the south. This is attributed to intense agricultural activities in the region. Samples from the eastern Gravel Plain aquifer have δ13C and dissolved inorganic carbon (DIC) values in the range from ? 10 to 17‰, and 12–100 mg C/l, respectively, while the range for those from the Ophiolite aquifer is from ? 11 to ? 16.4‰, and 16–114 mg C/l respectively. This suggests the control of C‐3 and C‐4 plants on DIC formation, an observation supported by the range δ13C of soil organic matter (from ? 18·5 to ? 22·1‰.) Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

15.
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 × δ2H (‰ ) ? 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.  相似文献   

16.
The origin and the chemical and isotopic evolution of dissolved inorganic carbon (DIC) in groundwater of the Okavango Delta in semi-arid Botswana were investigated using DIC and major ion concentrations and stable oxygen, hydrogen and carbon isotopes (δD, δ18O and δ13CDIC). The δD and δ18O indicated that groundwater was recharged by evaporated river water and unevaporated rain. The river water and shallow (<10 m) groundwater are Ca–Na–HCO3 type and the deep (≥10 m) groundwater is Na–K–HCO3 to HCO3–Cl–SO4 to Cl–SO4–HCO3. Compared to river water, the mean DIC concentrations were 2 times higher in shallow groundwater, 7 times higher in deep groundwater and 24 times higher in island groundwater. The δ13CDIC indicate that DIC production in groundwater is from organic matter oxidation and in island groundwater from organic matter oxidation and dissolution of sodium carbonate salts. The ionic and isotopic evolution of the groundwater relative to evaporated river water indicates two independent pools of DIC.  相似文献   

17.
Accurately quantifying the evaporation loss of surface water is essential for regional water resources management, especially in arid and semi-arid areas where water resources are already scarce. The long-term monitoring of stable isotopes (δ18O and δ2H) in water can provide a sensitive indicator of water loss by evaporation. In this study, we obtained surface water samples of Shiyang River Basin from April to October between 2017 and 2019. The spatial and temporal characteristics of stable isotopes in surface water show the trend of enrichment in summer, depletion in spring, enrichment in deserts and depletion in mountains. The Local Evaporation Line (LEL) obtained by the regression of δ2H and δ18O in surface water has been defined by the lines: δ2H = 7.61δ18O + 14.58 for mountainous area, δ2H = 4.19δ18O − 17.85 for oasis area, δ2H = 4.08δ18O − 18.92 for desert area. The slope of LEL shows a gradual decrease from mountain to desert, indicating that the evaporation of surface water is gradually increasing. The evaporation loss of stable isotopes in surface water is 24.82% for mountainous area, 32.19% for oasis area, and 70.98% for desert area, respectively. Temperature and air humidity are the main meteorological factors affecting the evaporation loss, and the construction of reservoirs and farmland irrigation are the main man-made factors affecting the evaporation loss.  相似文献   

18.
A systematic study of the chemo-isotopic characteristics and origin of the groundwater was carried out at six major qanats in the hyper-arid Gonabad area, eastern Iran. These qanats as a sustainable groundwater extraction technology have a long history, supporting human life for more than a thousand years in this region. The Gonabad qanats are characterized by outlet electrical conductivity (EC) values of 750 to 3900 µS/cm and HCO3-Na-Mg and Cl-Na water types. The Gonabad meteoric water line (GnMWL) was drawn at the local scale as δ2H = 6.32×δ18O + 8.35 (with R2 = 0.90). It has a lower slope and intercept than the global meteoric water line due to different water vapor sources and isotope kinetic fractionation effects during precipitation in this arid region. The altitude effects on isotopic content of precipitation data were derived as δ18O = (−0.0031 × H(m.a.s.l))−1.3). The δ2H and δ18O isotopes signatures demonstrate a meteoric origin of the groundwater of these qanats. The shift of the qanat's water samples from the local meteoric water line (LMWL) in a dry period with higher temperatures is most probably due to evaporation during the infiltration process and water movement in qanat gallery. Based on the isotopic results and mass balance calculations, the qanats are locally recharged from an area between 2000 to 2400 m.a.s.l of nearby carbonate formations and coarse alluvial sediments. The dissolution of evaporate interlayers in Neogene deposits deteriorates the groundwater quality, especially in Baidokht qanat.  相似文献   

19.
Abstract

Chemical and isotopic data of groundwater of the Upper Cretaceous aquifer in the Orontes basin, Syria, have been used to assess the groundwater geochemistry, the origin of groundwater recharge and groundwater residence time. The chemical data indicate that dissolution of evaporite minerals is the main process controlling groundwater mineralization. The composition of stable isotopes δ18O and δ2H, together with 14C activity, reflect the existence of three different groups: (a) groundwater in the Coastal Mountains with δ18O of –6.65‰, quite similar to modern-day precipitation, and high 14C (>50 pmC); (b) groundwater in the unconfined aquifer of the Hama Uplift, which has δ18O of –5.52‰ and 14C near 20 pmC, and is recharged locally; and (c) groundwater from the confined aquifer of the Homs Depression, which is characterized by more depleted δ18O,, –8.01‰, and low 14C (<7 pmC), and might be recharged in the northern piedmont of the Anti-Lebanon Mountains. The distinctive isotope signatures of the latter two groups indicate different recharge elevations and palaeoclimatic effects. The low recharge rate of the groundwater in the Hama Uplift aquifer, and the even slower recharge rate in the Homs Depression aquifer, are reflected by groundwater 14C residence times of 5 and over 22 Ka BP, respectively.

Editor D. Koutsoyiannis

Citation Al-Charideh, A., 2013. Recharge and mineralization of groundwater of the Upper Cretaceous aquifer in Orontes basin (Syria). Hydrological Sciences Journal, 58 (2), 452–467.  相似文献   

20.
Artificially enhancing recharge rate into groundwater aquifer at specially designed facilities is an attractive option for increasing the storage capacity of potable water in arid and semi‐arid region such as Damascus basin (Syria). Two dug wells (I and II) for water injection and 24 wells for water extraction are available in Mazraha station for artificial recharge experiment. Chemical and stable isotopes (δ2H and δ18O) were used to evaluate artificial recharge efficiency. 400 to 500*103 m3 of spring water were injected annually into the ambient shallow groundwater in Mazraha station, which is used later for drinking purpose. Ambient groundwater and injected spring water are calcium bicarbonate type with EC about 880 ± 60 μS/cm and 300 ± 50 μS/cm, respectively. The injected water is under saturated versus calcite and the ambient groundwater is over saturated, while the recovered water is near equilibrium. It was observed that the injection process formed a chemical dilution plume that improves the groundwater quality. Results demonstrate that the hydraulic conductivity of the aquifer is estimated around 6.8*10?4 m/s. The effective diameter of artificial recharge is limited to about 250 m from the injection wells. Mixing rate of 30% is required in order to reduce nitrate concentration below 50 mg/l which is considered the maximum concentration limit for potable water. Deuterium and oxygen‐18 relationship demonstrates that mixing line between injected water and ambient groundwater has a slope of 6.1. Oxygen‐18 and Cl? plot indicates that groundwater salinity origin is from mixing process, and no dissolution and evaporation were observed. These results demonstrate the efficiency of the artificial recharge experiments to restore groundwater storage capacity and to improve the water quality. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

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