Groundwater resources in the Jabal Al Hass region,northwest Syria: an assessment of past use and future potential   总被引：2，自引：1，他引：1  

Elco Luijendijk  Adriana Bruggeman 《Hydrogeology Journal》2008,16(3):511-530

In many cases, the development of groundwater resources to boost agricultural production in dry areas has led to a continuous decline in groundwater levels; this has called into question the sustainability of such exploitation. In developing countries, limited budgets and scarce hydrological data often do not allow groundwater resources to be assessed through groundwater modeling. A case study is presented of a low-cost water-balance approach to groundwater resource assessments in a 1,550 km² semi-arid region in northwestern Syria. The past development of irrigated agriculture and its effect on the groundwater system were studied by analysis of Landsat images and long-term groundwater level changes, respectively. All components of the groundwater balance were determined. Groundwater recharge was estimated using the chloride mass balance method. Over the past three decades, groundwater levels have declined, on average, 23 m, coinciding with a two-fold increase in the groundwater-irrigated area. Groundwater resources are currently depleted by a value that lies between 9.5×10⁶ and 118×10⁶ m³ year^?1, which is larger than can be compensated for by a future decrease in natural discharge or changes in boundary conditions. However, groundwater resources are likely to be sufficient to supply domestic and livestock needs in the area.  相似文献   

Hydrochemical and isotopic characteristics of groundwater in the Souss Upstream Basin, southwestern Morocco     

K. Dindane  L. Bouchaou  Y. Hsissou  M. Krimissa   《Journal of African Earth Sciences》2003,36(4):315-327

Heterogeneous shallow Plio-Quaternary formations of the Souss Plain represent the most important aquifer in southern High Atlas Mountains in Morocco. The present work was conducted in the Souss Upstream Basin to identify the chemical characteristics and the origin of groundwater in an aquifer under semi-arid climate. Isotopic and hydrochemical compositions combined with geological and hydrogeological data were used for this purpose. The total dissolved solids vary from 239 to 997 mg l⁻¹, and the following groundwater types are recognized: Ca²⁺–Mg²⁺–HCO₃⁻, Ca²⁺–Mg²⁺–SO₄²⁻ and Ca²⁺–Mg²⁺–Cl⁻. The groundwater is saturated and slightly supersaturated with respect to carbonate minerals and undersaturated with respect to evaporite minerals, which means that the groundwater composition is largely controlled by the dissolution of carbonate rocks known in the basin. The isotopic contents of groundwaters ranged from −8‰ to −5.2‰ for δ¹⁸O, from −52‰ to −34‰ for δD, and from 0 to 5.5 TU for tritium. The hydrogen (δD) and oxygen (δ¹⁸O) isotope signatures reveal a significant infiltration before evaporation takes place, indicating a major recharge directly from fractures in the crystalline and limestone formations of Atlas Mountains (above 800 m a.s.l.) and infiltration of surface water in the alluvial cones at the border of the Atlas basins. The very low tritium values suggest that the groundwater recharge follows a long flow path and a mixing between old and modern water is shown. However, a slight evaporation effect is noted in the southern part of the basin close to the Anti-Atlas Mountains.  相似文献   

Environmental impact of an urban landfill on a coastal aquifer (El Jadida, Morocco)     

Amina Chofqi  Abedelkader Younsi  El Kbir Lhadi  Jacky Mania  Jacques Mudry  Alain Veron 《Journal of African Earth Sciences》2004,39(3-5):509

The El Jadida landfill is one among many uncontrolled dumping sites in Morocco with no bottom liner. About 150 tons/day of solid wastes from mixed urban and industrial origins are placed directly on the ground. At the site of this landfill, the groundwaters circulate deeply (10–15 m) in the Cenomanian rock (calcareous–marl), which is characterised by an important permeability from cracks. The soil is sand–clay characterized by a weak coefficient of retention.The phreatic water ascends to the bottom of three quarries, which are located within the landfill. These circumstances, along with the lack of a leachate collection system, worsen the risks for a potential deterioration of the aquifer.To evaluate groundwater pollution due to this urban landfill, piezometric level and geochemical analyses have been monitored since 1999 on 60 wells. The landfill leachate has been collected from the three quarries that are located within the landfill. The average results of geochemical analyses show an important polluant charge vehiculed by landfill leachate (chloride = 5680 mg l⁻¹, chemical oxygen demand = 1000 mg l⁻¹, iron = 23 000 μg l⁻¹). They show also an important qualitative degradation of the groundwater, especially in the parts situated in the down gradient area and in direct proximity to the landfill. In these polluted zones, we have observed the following values: higher than 4.5 mS cm⁻¹ in electric conductivity, 1620 and 1000 mg l⁻¹ respectively in chlorides and sulfate (), 15–25 μg l⁻¹ in cadmium, and 60–100 μg l⁻¹ in chromium. These concentrations widely exceed the standard values for potable water.Several determining factors in the evolution of groundwater contamination have been highlighted, such as (1) depth of the water table, (2) permeability of soil and unsaturated zone, (3) effective infiltration, (4) humidity and (5) absence of a system for leachate drainage. So, to reduce the pollution risks of the groundwater, it is necessary to set a system of collection, drainage and treatment of landfill leachates and to emplace an impermeable surface at the site of landfill, in order to limit the infiltration of leachate.  相似文献   

Origin of the high variability of water mineral content in the bedrock aquifers of Southern Madagascar     

V. Rabemanana  S. Violette  G. de Marsily  H. Robain  B. Deffontaines  P. Andrieux  M. Bensimon  A. Parriaux 《Journal of Hydrology》2005,310(1-4):143-156

This study assesses the causes of the high spatial variability of the mineral content of groundwater in crystalline bedrock of Southern Madagascar. Although many kilometres from the coast and at a mean altitude of 400 m a.s.l, wells drilled in this area produce water with electrical conductivities in the range of 300–30,000 μS cm⁻¹ with a high spatial variability. Chemical and isotopic data are used to identify the processes involved in the groundwater mineralization. It is shown that the chemical composition of the groundwater in this region has its origin in (i) normal silicate and carbonate weathering reactions and (ii) input of marine salts, probably via rainfall recharge, modified by evapo-concentrative processes probably including precipitation and re-dissolution of secondary evaporites in the unsaturated zone. To obtain a better understanding of the spatial salinity distribution, well parameters such as yields, weathered zone thickness, weathered materials and morphological positions (upper slope, mid-slope, lower slope or valley bottom) are scrutinized.

A correlation was found between high salinity and low flow, shallow groundwater environments (flat hill tops, valley bottoms, weakly developed and clayey weathered zones) and between low salinity and high flow environments (granular, well-developed weathered zones and situation on valley slopes).  相似文献   

Climatic response of thick leaf spruce (Picea crassifolia) tree-ring width at different elevations over Qilian Mountains, northwestern China   总被引：3，自引：0，他引：3  

X. Gou  F. Chen  M. Yang  J. Li  J. Peng  L. Jin 《Journal of Arid Environments》2005,61(4):513-524

Tree-ring cores of thick leaf spruce (Picea crassifolia) taken from four sites at different elevations, in the middle of the Qilian Mountains, in the arid and semi-arid region of northwestern China, were used to develop four tree-ring width chronologies using standard dendrochronological methods. Results indicate that with increasing altitude the chronologies’ year-to-year variations decreased. Hence, the sensitivity of the tree-ring chronologies to climate decreases with altitude. Further analysis showed that the significant limiting factor on tree growth is spring precipitation. Measurements of stomata density and leaf dry weight suggest the species’ ecological adaptation strategy changes with elevation. At high elevation the metabolic rate of thick leaf spruce decreases, thus showing the effect of the climate.  相似文献   

Groundwater flow regime under natural conditions as inferred from past evidence and contemporary field observations in a semi-arid basin: Cuenca de la Independencia, Guanajuato, México     

I. Navarro de Len  J. Grfias-Soliz  J. Mahlknecht 《Journal of Arid Environments》2005,63(4):756-771

This study was carried out in the Cuenca de la Independencia, a semi-arid basin in Central Mexico. The objective is to describe the main features of a groundwater flow regime under natural conditions, based on groundwater discharge manifestations. Information obtained from paleoecological, paleontological, archaeological and historical data suggests that, prior to heavy development (starting in the 1950s), the hydrogeologic regime was characterized by a larger groundwater availability in a more humid and colder climate. Manifestations associated to groundwater discharges are springs, lagoons, wetlands, saline soils, chalcedony deposits, phreatophytes, thermalism, and artesianism. The different types of manifestations and their position in the basin indicate the influence of groundwater flow systems hierarchically nested, forming concentric zones at ground level. The groundwater flow regime corresponds to a classical gravity-induced flow system with generation of local, intermediate and regional patterns. Integrating several types of data to establish the flow geometry and its dynamics has proven a useful tool to increase understanding of the original groundwater regimes. This approach can also be applied in other over-exploited semi-arid basins.  相似文献   

Changing drainage patterns in a semi-arid area and their effects on groundwater resources     

Sally E. Sutton 《地球表面变化过程与地形》1987,12(5):567-570

The magnitude of groundwater resources is poorly correlated with surface catchment area in a group of wadi bottom alluvial aquifers in Northern Oman. It is suggested that this is due to progressive water gap captures across a limestone ridge.  相似文献   

半干旱区内陆湖泊透明度高光谱估测模型研究——以松嫩平原查干湖为例   总被引：2，自引：0，他引：2       下载免费PDF全文

宋开山  张柏  王宗明  段洪涛  张渊智  李方 《水科学进展》2006,17(6):790-796

通过实测查干湖高光谱数据,建立透明度(Secchi Disk Depth,SDD)单波段估测模型、比值估测模型以及神经网络高光谱估测模型,并以确定性系数R2以及剩余残差RMSE为指标进行了验证.通过对单波段估测模型和比值估测模型进行比较发现,单波段模型估测结果与比值模型相差无几,而水体透明度经对数处理有利于模型精度提高,但是神经网络模型是三者中最优的.查干湖透明度高光谱定量估测模型的建立,有利于今后利用遥感影像,对查干湖水体透明度进行全面估测,对于研究和监测查干湖水体水质状况有重要意义.  相似文献   

The generation and redistribution of overland flow on a massive oxic soil in a eucalypt woodland within the semi-arid tropics of North Australia     

Mike Bonell  John Williams 《水文研究》1986,1(1):31-46

There is a dearth of knowledge on the runoff processes of eucalypt woodland communities in the semi-arid tropics of Australia. The work was undertaken on a 100 m transect of a 0·8 degree hillslope typical of the ‘smooth plainlands’ of central-north Queensland. This paper introduces a new experimental design for measuring overland flow in such areas by way of a cascade system of unbounded runoff plots which allow the inputs and outputs between troughs to be calculated. Most storms generate overland flow. Time to overland flow ranges between 1 and 18 min where rain intensities are above 10mm hr⁻¹ and when the average detention storage of 3·6 mm is exceeded. The bare soil surfaces within the scattered grass understory control the runoff generation process through the temporal variability of field saturated hydraulic conductivity. The study demonstrated that overland flow is mainly redistributed over the freely-draining oxic soil. Some areas export more overland flow than they gain from upslope (runoff), others gain more overland flow than they export (runon). Over the study period only 2 per cent of total rain is transferred out of this 100 m transect as overland flow due to the short duration of storms, the relatively high soil permeability, and the low slope angle. The remainder adds to the large soil water store or deep drainage. The variability of runoff–runon over these ‘smooth plainlands’ highlights how results from bounded plots would be misleading in such areas.  相似文献   

Groundwater chemistry and mass transfers in the Independence aquifer,central Mexico,by using multivariate statistics and mass-balance models   总被引：2，自引：0，他引：2  

J.?MahlknechtEmail author  B.?Steinich  I.?Navarro de León 《Environmental Geology》2004,45(6):781-795

In the light of progressive depletion of groundwater reservoir and water quality deterioration of the Independence aquifer, an investigation on chemical data of dissolved major and minor constituents in 246 recent groundwater samples was performed. The main objective was the detection of processes responsible for the geochemical evolution and mineralization throughout the area. Multivariate techniques revealed different sources of solutes (a) dissolution of calcium and magnesium carbonate minerals, (b) weathering of acid volcanic minerals, (c) alteration of manganese containing alkaline silicates, (d) leaching of halite deposits of meteoric origin, (e) contamination from agricultural and urban wastewaters, and (f) evaporative effects due to intensive irrigation. Although nitrate contamination is associated with pollution from intensive cultivated areas, natural contamination plays an important role in the study area. The investigation reveals that weathering of acid volcanic rocks (rhyolite) and oxidation of arsenic bearing sulfide minerals are the responsible processes for high fluorine (up to 16 mg/l) and arsenic (up to 0.12 mg/l) contents, respectively, exceeding the Mexican maximum admissible concentration for drinking water. Except for kaolinite, all recharge processes are dissolution oriented (CO₂, calcite, dolomite, K-feldspar, plagioclase). Silicate precipitation (amorphous silica and chalcedony) is of growing importance in discharge zones. Cation exchange is not an important issue in the whole study area.  相似文献