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51.
Seawater intrusion into the shallow aquifer in the Syrian coast, north of Latakia (Damsarkho, Ras Ibn Hani) and south of Tartous
(Al Hamidieh, Ein Zarka) was studied using hydrochemical and isotopic techniques. The electrical conductivity (EC) distribution
map north of Latakia revealed that mixing in this area is the consequence of a frontal intrusion of seawater within the fresh
groundwater aquifer which, in turn, results from intensive pumping since the 1960s which has lowered the water table inland
below sea level. In Ein Zarka, south of Tartous, in contrast, the EC distribution revealed that seawater intrusion is due
to local up-coning as a result of intensive pumping. The deuterium and oxygen-18 relationship is that of a mixing line with
a slope of 5.55, indicating an intrusion between freshwater and seawater. In addition, the relationship between oxygen-18
and chloride reveals that the mixing has a dominant role compared to evaporation process. The mixing ratios are estimated
to be between 6 and 10% north of Latakia, while they do not exceed 3% south of Tartous. A tritium model was applied to compute
the “mean transit time”, which is estimated to be around 10 years, on average, to reach the equilibrium that existed originally
between the fresh groundwater and seawater, provided that severe pumping is completely halted and the aquifer is naturally
recharged by rainfall and deep percolation of irrigation water, thereby allowing the restoration of the hydraulic gradient.
This paper is dedicated to the memory of Dr. Y. Yurtsever. 相似文献
52.
Relationship between point rainfall, average sampled rainfall and ground truth at the event scale in the Sahel 总被引：2，自引：0，他引：2
Abou Amani Thierry Lebel 《Stochastic Environmental Research and Risk Assessment (SERRA)》1998,12(2):141-154
Geostatistical techniques are used to quantify the reference mean areal rainfall (ground truth) from sparse raingaugenetworks.
Based on the EPSAT-Niger event cumulative rainfall, a linear relationship between the ground truth considered as the mean
area rainfall estimated from the densely available raingauge network and the area rainfall estimated from sparse network are
derived. Also, a linear relationship between the ground truth and point rainfall is established. As it was reported experimentally
by some authors, the slope of these relationships is less than one. Based on the geostatistical framework, the slope and the
ordinate at the origin can be estimated as a function of the spatial structure of the rainfall process. It is shown that the
slope is smaller than one. For the special case of one gauge inside a fixed area or a Field Of View (FOV), an areal reduction
factor is derived. It has a limit value which depends only on the size of the area and the spatial structure of the rainfall
process. The relative variance error of estimating the FOV cumulative rainfall from point rainfall is also given. 相似文献
53.
This work deals with the tectonic interpretation of an alignment of more than 300 sinkholes stretching along the Jordanian coast of the Dead Sea, Ghor Al Haditha area. Its dimensions are 6 km long with a width of 600 m. Sinkholes appeared during the last decades as a consequence of the very rapid lowering of the lake level. The linear shape was inferred from ground collapse inventories carried out between 1991 and 2008. The lineament is replaced and analyzed in its structural setting at regional and local scales. Its direction (N 24° E) is sub‐parallel to the ones displayed by many focal mechanisms, especially the one associated with the earthquake of the 23 April, 1979 (mb = 5·1; N 20° E ± 5°), which is representative of all focal mechanisms calculated on a fault plane compatible with the general direction of the Jordan‐Dead Sea Transform fault system for the east coast of the Dead Sea area. The alignment of sinkholes is constituted by 13 minor linear segments separated by as many empty spaces. Four minor linear units present an en‐echelon arrangement from which one can deduce the presence of a local extensional stress field. In this context, the sinkhole locations provide information of subsurface discontinuities interpreted as hidden fractures. In a close future, such results could support the work of decision‐makers and engineers in the projected development of the area. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
54.
The effects of climate change and overexploitation are being strongly perceived in the studied area and the springs discharge is obviously affected. In this paper, Ras El Ain spring discharge and precipitation were analyzed by normalized methods on an yearly timescale. The deficit of Ras El Ain spring discharge due to overexploitation factors and drought effects was estimated. Cumulative drought analyses were carried out using SPI10 and SQI10. Finally, the decreasing trends of the spring discharge due to the deficiency in rainfall were analyzed. The main results reveal that the annual mean deficit of Ras El Ain spring discharge due to overpumping was between 32 and 45%, whereas, annual mean deficit related to drought was between 22 and 35% on average, during the last 30 years (post-1984). The moving averages of SPI and SQI delineate very well the drought periods during last three decades. The cumulative droughts using SPI10 and SQI10 reveal that wet period (pre-1984) with positive values was characterized by high precipitation and spring discharge. Overexploitation period (1984–1989) is distinguished by decreasing SQI10 values whereas, SPI10 is almost stable. The response of the karst system to the precipitation signal has been changed, during the drought period (1990–2000), and the spring behaviour has been modified due to the first overexploitation period. Finally, overexploitation period (2001–2008) is related to the second phase of groundwater intensive pumping for irrigation purposes. Consequently, this period is completely catastrophic causing the drying up of the spring. The decreasing trends analyzed using DPI and DQI showed annual decreasing rates relative to the mean values of ?0.268% and ?0.105%, respectively. Thus, the results of theoretical model reveal that precipitation will decrease by about \(\hbox {DPI} = -20.7\)% and the discharge will decline by about ?9.2% by 2050. Consequently, the declining discharge due to climatic variation under natural conditions as pre-1984 was about 10%. Whereas, the catastrophic drying up of the spring was probably the consequence of the anthropogenic effects. Accordingly, it requires the development of sustainable water resources management program to reduce long-term drought risks, restore the groundwater reservoir and minimize the overexploitation effects on spring discharge. 相似文献
55.
Abstract The paper discusses aspects of the isotopic composition (tritium and stable isotopes) of precipitation, which was monitored from 2000 to 2003 at 12 stations in Syria. The seasonal variations in δ18O are smaller at the western stations than at the eastern ones due to low seasonal temperature variations. A good correlation between δ2H and δ18O was obtained for each station, and the slopes of the local meteoric water lines are significantly lower than the Global Meteoric Water Line. Values of d-excess decrease from 19‰ at the western stations to 13‰ at the eastern ones, indicating the influence of precipitation generated by air masses coming from the Mediterranean Sea. A reliable altitude effect represented by depletion of heavy stable isotopes (δ18O and δ2H), of about??0.21‰ and??1.47‰ per 100 m elevation, respectively, was observed. Monthly tritium contents in precipitation, and seasonal variations, are less at the western stations than at the eastern ones. The weighted mean tritium values are between 3 and 9 TU, and increase with distance from the Syrian coast by 1 TU/100 km. Citation Al Charideh, A. R. & Abou Zakhem, B. (2010) Distribution of tritium and stable isotopes in precipitation in Syria. Hydrol. Sci. J. 55(5), 832–843. 相似文献
56.
Y. Klinger J. P. Avouac L. Dorbath N. Abou Karaki N. Tisnerat 《Geophysical Journal International》2000,142(3):769-782