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51.
Natural and artificial recharge investigation in the Zéroud Basin,Central Tunisia: impact of Sidi Saad Dam storage 总被引:1,自引:0,他引:1
Sarra Bel Hadj Salem Najiba Chkir Kamel Zouari Anne Laure Cognard-Plancq Vincent Valles Vincent Marc 《Environmental Earth Sciences》2012,66(4):1099-1110
Hydrochemical and isotopic data of waters from the Zéroud aquifer have been used to potentially provide a means for locating occurrences and to trace movements of a variety of natural and anthropogenic recharge waters in the Zéroud Basin, Central Tunisia. Geochemical data have been measured during the dam water release, from May to September 2005, with a sampling time step of 15 days. An implication of dam water has been demonstrated that is noticeable up along the main flow path to a distance of 10 km far from the injection site. Environmental isotopes 2H, 18O and 3H of water molecule were studied to investigate the effect of dam water on the hydrological system, and an isotope balance was established to compute the contribution of water storage component in groundwater. Based on isotopic mass balance, we assess that an average of 13% of total groundwater in the upper aquifer came from dam water storage. Three distinctive recharge waters in the aquifer can be determined. Water from local rainfall (pre-dam Zéroud River) that infiltrated into the boundaries of the Draa Affane Mountain was easily distinguished from the water influenced by anthropogenic recharge located in the Zéroud right rivulet. Distinguishable isotopic signatures of native wadi Zéroud recharge due to “recent lineal recharge” through the riverbed were also identified. 相似文献
52.
Mathematical Geosciences - Natural draft dry cooling towers (NDDCTs) are a type of cooling technology used in thermal power plants, including geothermal power plants. Interest from industry in this... 相似文献
53.
Modelling of rutting of two flexible pavements with the shakedown theory and the finite element method 总被引:1,自引:0,他引:1
Cyrille Chazallon Georg Koval Pierre Hornych Fatima Allou Saida Mouhoubi 《Computers and Geotechnics》2009
This paper presents a finite element program, for the modelling of rutting of flexible pavements. In its present version, the program incorporates a permanent deformation model for unbound granular materials based on the concept of the shakedown theory developed by Zarka for metallic structures under cyclic loadings and has been used to estimate the permanent deformations of unbound granular materials (UGM) subjected to traffic loading. The calculation is performed in two steps: the first step consists in modelling the resilient behaviour of the pavement in 3D, using non-linear elastic models, to determine the stress field in the pavement. Then stress paths are derived and used to calculate the permanent deformations and the displacements, using a Drucker–Prager yield surface. An application to the prediction of the permanent deformations of experimental pavements with an unbound granular base, tested on the LCPC pavement testing facility is presented. 相似文献
54.
Kamel Amri Ghilles Rabai Imene Meriem Benbakhti Mohamed Nadir Khennouche 《Arabian Journal of Geosciences》2017,10(4):87
Djelfa area in the central Saharan Atlas is characterized by its high lithological diversity with different facies from the Triassic to the Tertiary. The lack of published geological maps of the region (Djelfa) prompted us to test specific processing of satellite images (ratio bands, principal component analysis) in order to establish a lithological discrimination of the region. Several treatments allowed us to map the lineaments highlighting the various tectonic structures of the region. The combination of field and remote sensing data pointed out the double influence of the E-W Eocene and N-S Miocene phases in the structuration of these regions. As a large part of the Djelfa area is inaccessible, the obtained results undeniably contribute to a better understanding of the local geology. 相似文献
55.
Quantifying regional groundwater flow between Continental Intercalaire and Djeffara aquifers in southern Tunisia using isotope methods 总被引:4,自引:0,他引:4
Large-scale interaction between the Continental Intercalaire and the Djeffara aquifer systems in the southeast of Tunisia
has been investigated with the aid of chemical and isotopic tracers. Two distinct groundwater types have been identified:
(1) the Continental Intercalaire groundwater characterized by elevated temperatures (50–61.4°C), low δ18O (−8.4 to−7.87) and δ2H (−67.2 to−59) values and negligible radiocarbon content, both testifying its great age dating from the late Pleistocene
period, and (2) the Djeffara groundwater with distinctly heavier isotopic composition (δ18O = −8.31 to −5.80, δ2H = −65.9 to −31.9). The Djeffara groundwaters reveal a distinct changes of physico-chemical and isotopic parameters near
El Hamma Faults in the northwestern part of the Djeffara basin. These changes could possibly be explained by a vertical leakage
from the Continental Intercalaire aquifer through El Hamma Faults. The mixing proportions inferred from stable isotope mass
balance prove that the contribution of the Continental Intercalaire to the recharge of Djeffara aquifer is very significant
and may reach 100% in the El Hamma region and in the northern part of Gabes. Isotope tracers strongly suggest that recent
recharge to the Djeffara aquifer system is very limited. Its current yield, particularly in its central and northern parts
can be maintained only thanks to large-scale underground inflow from the Continental Intercalaire aquifer system, which carries
late Pleistocene palaeowater. Consequently, current exploitation of groundwater resources of the Djeffara aquifer has non-sustainable
character. 相似文献
56.
Hydrochemistry of groundwater is largely determined by both natural processes, such as dissolution, cation exchange, mixing,
evaporation; and anthropogenic activities, which can affect the aquifer systems by contaminating them or by modifying their
hydrological cycle. Both natural and anthropogenic processes vary in time and space; which is reflected in groundwater hydrochemistry
variation. The objective of this study is the determination of the main hydrogeochemical processes that affect the quality
of shallow groundwaters in the Grombalia basin, located in the Cap Bon Peninsula, north-eastern Tunisia. In this area, the
chemical composition of groundwater is mostly characterized by Na–Cl–NO3–Ca water type which reveals the implication of natural and anthropogenic major factors. Natural factors are dissolution of
evaporatic minerals, i.e. halite and gypsum and cation exchange with clays, while anthropogenic factors are pollution with
industrial Sr-rich waste water and return flow of irrigation water, highly contaminated by MgSO4 and methyl-bromide fertilizers. 相似文献
57.
Estimating suspended sediment yield, sedimentation controls and impacts in the Mellah Catchment of Northern Algeria 总被引:1,自引:0,他引:1
This paper is an assessment of the suspended sediment yield in the Mellah Catchment of northern Algeria. We use discharge–sediment load relationships to explore the variability of water discharge and sediment load, and to investigate the impact of geomorphic factors disturbance on erosion and sedimentation. Suspended sediment load was analyzed in the Mellah Catchment (550 km²) which was controlled by a gauging station to measure discharge and sediment transport. The relations between daily mean sediment concentration and daily mean water discharge were analyzed to develop sediment rating curves. For storms with no water samples, a sediment rating curve was developed. The technique involves stratification of data into discharge-based classes, the mean of which are used to fit a rating curve according to single flow data and season to provide various rating relationships. The mean annual sediment yield during the 24 years of the study period was 562 T km?2 in the Mellah Catchment. This drainage basin had high rainfall and runoff, the erosion was high. The high sediment yield in the Mellah basin could be explained by a high percentage of sparse grassland and cultivation developed on shallow marly silty-clayey soils with steep slopes often exceeding 12%. Almost all suspended sediment loads are transported during storm events that mainly occur in the winter and spring heavy and medium downpours. The scarceness of these events leads to a very large interseasonal variability of the wadi sediment fluxes. The negative impacts of this enhanced sediment mobility are directly felt in the western part of the basin which shows many mass movements, bank and gully erosion because cultivated areas are often bared during autumnal brief flash floods and furrowed downslope during the winter season. 相似文献
58.
Ahmed Aly Kamel 《Celestial Mechanics and Dynamical Astronomy》1975,12(4):425-438
Ignoring luni-solar perturbations, analytical solution for longitude deviation of the ‘stroboscopic’ mean center of 24-h satellites ground trace in the neighborhood of a prespecified station is obtained. The initial semimajor axis for two-maneuver east-west stationkeeping is then deduced. Finally, the luni-solar long and short period effects on this initial semimajor axis are discussed. 相似文献
59.
We extend the construction of the Jupiter-Saturn theory to include all the terms up to the seventh order in the masses. The Hori-Lie transformation technique is employed. The Jacobian coordinates are adopted and the theory is expressed in terms of the canonical non-singular variables of H. Poincaré. 相似文献
60.
In this part we find out the 24 equations of secular perturbation equations for the subsystem J-S-U-N. The solution of these equations by the Lagrange-Laplace procedure and the Eigen value Eigen vector is analysed. Also we refer to Hurwitz theorem to test stability. 相似文献