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31.
Lamyaa Kacem Mbark Agoussine Brahim Igmoullan Soraya Mokhtari Hicham Amar 《Water Resources》2016,43(2):395-401
The National Park of Toubkal is located in the High Moroccan Atlas Mountains, one of the regions sheltering the highest summits of North Africa (Mount Toubkal with an elevation of 4167 m). The park is characterized by very important water resources, including Ifni Lake, which is the highest natural lake in Morocco (with an elevation of 2320 m). This lake is located on the southern side of Mt. Toubkal. This area has never been the object of an environmental or hydrological study. The objective of the current study was the characterization of Ifni Lake and the spring waters located in this area, as the basis of a framework to protect natural resources in northern Africa. The hydrochemical composition of water determines its origin and relationship with its catchment. Hydrochemical studies were carried out to assess the ions water composition, and processes governing the hydrochemistry of Ifni Lake water and the springs in the study area. A total of 20 water samples were collected in 2013 and analyzed for various parameters such as pH, electrical conductivity, and major ions. The physico-chemical analysis of the Ifni Lake water showed that this is the least mineralized water studied in this region, having a bicarbonate, calcium, and magnesium as dominate ions. Also there is a relationship between the hydrochemical composition of Ifni Lake and spring waters. 相似文献
32.
Seasonal variation of particulate organic compounds in atmospheric PM10 in the biggest municipal waste landfill of Algeria 总被引：1，自引：0，他引：1
Riad Ladji Noureddine Yassaa Angelo Cecinato Brahim Youcef Meklati 《Atmospheric Research》2007,86(3-4):249-260
The average composition and seasonal variations of atmospheric organic particulates with respect to n-alkanes, n-alkanoic acid, polycyclic aromatic hydrocarbon (PAHs), and nitrated polycyclic aromatic hydrocarbons (N-PAHs) were determined at the biggest municipal waste landfill in Algeria located in Oued Smar, 13 km east of downtown Algiers. Samplings were carried out from August 2002 to February 2003, and organic compounds adsorbed in air particles having an aerodynamic diameter lower than 10 μm (PM10) were characterized using gas chromatography coupled with mass spectrometric detection (GC/MSD). Total concentrations ranged from 828 to 11,068 ng per cubic meter of air for n-alkanes, from 1714 to 21,710 ng per cubic meter of air for n-alkanoic acids, from 13 to 212 ng per cubic meter of air for PAHs and from 93 to 205 pg per cubic meter of air for N-PAHs. n-Alkanoic acids accounted for 85 and 56% of the total organic composition of the aerosol measured in summer and winter, respectively, were the biggest fraction. The distribution profiles and the diagnostic ratios of some marker compounds allowed to identify the combustion and microbial activity as the major sources of particulate organic pollutants associated with direct emission. The year-time dependence of organic fraction content of aerosol in Oued Smar appeared to be related to average meteorological conditions as well as variability of rate and nature of materials wasted into the landfill. 相似文献
33.
Malki Mouna Choukr-Allah Redouane Bouchaou Lhoussaine Ait Brahim Yassine Hirich Abdelaziz Barbara Reichert 《Arabian Journal of Geosciences》2016,9(10):566
The Chtouka-Massa area in Southern Morocco has shown an increase in water scarcity during the last decades, caused mainly by withdrawal of water resources aggravated by agricultural intensification and climate change impacts. To better understand the changes of groundwater quality, a sampling campaign was conducted in many wells during March 2015 and compared to historical chemical data from the hydraulic basin agency, as well as previous studies performed at Ibn Zohr University. All data were used to assess the spatial-temporal evolution of nitrate and salinity relevant to the recent sampling. This paper describes the current state of groundwater quality in the Chtouka-Massa zone with an overview of different sources of water mineralization and the nitrate evolution in an agricultural area. Our results indicate a general increase in mineralization from the north to the south, and from the east to the west. The plain, dominated by farms, shows a relatively high conductivity (up to 2000 μS/cm), while in both costal area and Anti-Atlas Mountain the water salinity shows a gradient increase from the north to the south. However, the highest electrical conductivity is observed along the Massa River. The water type is bicarbonate, chloride, and sodium for farm samples, while from the other parts, it is mostly dominated by chloride and sodium. The spatial-temporal analysis of nitrates generally shows an increasing trend. However, the levels remain overall lower than the limit. The temporal evolution of control points set by the hydraulic agency shows a decreasing trend decline that can be explained by the improvement of agriculture practices, including the conversion towards drip irrigation mode. Different chemical tracers highlighted some processes involving the changes of mineralization of groundwater (e.g., irrigation water return, marine intrusion, and water/rock interaction). The results will be used to improve water management in this area showing water quality degradation. 相似文献
34.
A survey on the epiphytic microorganisms growing on Posidonia oceanica leaves was conducted along a depth transect along the coast of Eastern Tunisia (Mahdia). Samples were collected by SCUBA diving at depths of 3, 5, 10 and 12 m in July 2008 and January 2009. A total of 58 microepiphyte taxa were identified. Multivariate analyses revealed temporal and spatial variation of the abundance of epiphytic microalgae. Water motion, light availability, temperature and motility of species seem to be responsible of temporal and bathymetric variations of epiphytic microalgae. Unlike diatoms, dinoflagellates were more abundant in deep waters, suggesting that they are more vulnerable to hydrodynamics. The significant correlation between leaf area index and abundance of epiphytic species indicates that the phenological parameters of the host plant influence the abundance of the epiphytic microorganisms. Among the epiphytic dinoflagellates, our data showed a great number of potentially toxic species (Alexandrium minitum, Amphidinium carterae, Karenia selliformis, Coolia monatis, Karlodinium veneficum, Ostreopsis siamensis, Prorocentrum concavum, Prorocentrum minimum, Prorocentrum rathymum and Prorocentrum lima). These species were more abundant in the deep station under more sheltered conditions than found at inshore shallower stations, which are subjected to high water motion. 相似文献
35.
Muhammad Nauman Malik Mehdi Murtuza Iqbal Asif Bakar Muhammad Saifullah Abu Brahim Aissa Dk Nur Afiqah Jalwati Puteri Amer Farhan Rafique 《地下水科学与工程》2014,7(4):373-382
In many circumstances involving heat and mass transfer issues, it is considered impractical to measure the input flux and the resulting state distribution in the domain. Therefore, the need to develop techniques to provide solutions for such problems and estimate the inverse mass flux becomes imperative. Adaptive state estimator (ASE) is increasingly becoming a popular inverse estimation technique which resolves inverse problems by incorporating the semi-Markovian concept into a Bayesian estimation technique, thereby developing an inverse input and state estimator consisting of a bank of parallel adaptively weighted Kalman filters. The ASE is particularly designed for a system that encompasses independent unknowns and /or random switching of input and measurement biases. The present study describes the scheme to estimate the groundwater input contaminant flux and its transient distribution in a conjectural two-dimensional aquifer by means of ASE, which in particular is because of its unique ability to efficiently handle the process noise giving an estimation of keeping the relative error range within 10% in 2-dimensional problems. Numerical simulation results show that the proposed estimator presents decent estimation performance for both smoothly and abruptly varying input flux scenarios. Results also show that ASE enjoys a better estimation performance than its competitor, Recursive Least Square Estimator (RLSE) due to its larger error tolerance in greater process noise regimes. ASE’s inherent deficiency of being slower than the RLSE, resulting from the complexity of algorithm, was also noticed. The chosen input scenarios are tested to calculate the effect of input area and both estimators show improved results with an increase in input flux area especially as sensors are moved closer to the assumed input location. 相似文献
36.
Eliseo Clementini Brahim Lejdel Sabrina Mazzagufo Robert Laurini 《Transactions in GIS》2021,25(1):491-515
In GIS, spatial analysis is based on the use of spatial operations such as testing the spatial relations between features. Often, such tests are invalidated by errors in datasets. It is a very common experience that two bordering regions which should obey the topological relation “meet” fall instead in the “overlap” category. The situation is exacerbated when applying topological operators to regions that come from different datasets, where resolution and error sources are different. Despite the problem being quite common, up to now no standard approach has been defined to deal with spatial relations affected by errors of various origins. Referring to topological relations, we define a model to extend the eight Egenhofer relations between two simple regions: we call them homological relations (H‐relations). We discuss how exact topological relations can be extracted from observed relations and discuss the case of irregular tessellations, where errors have the most impact on vector data. In the proposed case study within the domain of geographic crowdsourced data, we propose algorithms for identifying homological regions and obtaining a corrected tessellation. This methodology can be considered as a step for quality control and the certification of irregular tessellations. 相似文献
37.
Spatial scale variability in shoot density and epiphytic leaves of Posidonia oceanica on Kerkennah Island (Tunisia) in relation to current tide effects 
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下载免费PDF全文 Mounir Ben Brahim Lotfi Mabrouk Asma Hamza Mabrouka Mahfoudhi Abderahmen Bouain Lotfi Aleya 《Marine Ecology》2015,36(4):1311-1331
A study was undertaken of the patterns of spatial variability, epiphytic biomass and distribution of epiphytic fauna and flora of Posidonia oceanica. Samples were taken at four stations located approximately 4 km apart, exposed to different current conditions. Stations A and B, situated near the Oued Mimoun tidal channel with its relatively strong bi‐directional flows, were affected by high current tide. The other two stations, North Oued Mimoun (L1) and South Oued Mimoun (L2), were located further from the channel, in low current tide conditions. Sampling was conducted in the Attaya area of Kerkennah Island (Tunisia) in August 2009 at depths between 2 and 3 m, with the results indicating differences among the stations. Shoot density decreased when exposed to high levels of hydrodynamic activity generated by current tides whereas the epiphytic biomass of P. oceanica leaves decreased at sheltered stations located far from the channel. Epiphytic algae such as Heterokontophyta, Rhodophyta and Chlorophyta, and epiphytic fauna represented by Bryozoa, Hydrozoa, Annelida, Porifera and Tunicata, dominated the epiphytic assemblages and were abundant at the station most exposed to high current tide hydrodynamics. Cyanobacteria, however, were dominant in stations exposed to low current tide. 相似文献
38.
The Kebilli region is located in the Southwestern part of Tunisia, and is characterized by the presence of deep and shallow geothermal systems (continental intercalary and complex terminal). Chemical and isotopic contents are used to classify the type and determine the origin of thermal water. An evaluation of reservoir temperature and a possible geothermal fluid mixing are also carried out. Both continental intercalary-deep aquifer and complex terminal-shallow aquifer are of Na–(Ca)–Cl–(SO4) mixed water type. The use of different geothermometers and the computation of saturation indexes for different solid phases suggests that the thermal reservoir temperature of the continental intercalary is between 92 and 105 °C, while the fluid temperature from the shallow complex terminal aquifer ranges from 50 to 75 °C. Also, the isotopic data indicates the old origin of all groundwater of Southwestern Tunisia. Mixing effects characterizing the continental intercalary and the complex terminal aquifers were identified using δ2H and δ18O relationship. It appears that the upward movement of thermal water from the deep aquifer to shallow ones is probably due to the abundant fractures in the research area. 相似文献
39.
Makram Anane Bessem Abidi Fethi Lachaal Atef Limam Salah Jellali 《Hydrogeology Journal》2013,21(3):715-731
Three vulnerability index models were applied to assess the pollution potential of Nabeul-Hammamet shallow aquifer, Tunisia: DRASTIC, Pesticide DRASTIC and the Susceptibility Index (SI). An output map layer of each one was obtained using a geographic information system (GIS). The SI layer was overlain with DRASTIC and Pesticide DRASTIC and the percentage areas of agreement and divergence in vulnerability categories were extracted. DRASTIC results suggest the aquifer has mostly low vulnerability. Pesticide DRASTIC and SI identify three vulnerability categories (low, moderate, high) in the aquifer. Published data on current chemical groundwater composition indicate that parts of the aquifer are highly contaminated, revealing that DRASTIC underestimates the risk of pollution; Pesticide DRASTIC and SI reflect this risk better. Agreement in vulnerability categories between the two last models is found for 64 % of the aquifer area. To help manage land-use allocation and prevent Nabeul-Hammamet-aquifer contamination, DRASTIC is not recommended. Pesticide DRASTIC and SI are recommended but for slightly different applications. SI helps in the monitoring of current vulnerable areas and, thus, in contamination prevention. Pesticide DRASTIC could better intervene as a criterion in a multi-criteria analysis to select the best sites for specific on-the-ground practice or future land use. 相似文献
40.
E. A. Toto A. El Miloudi M. El Basri M. Hafid L. Zouhri S. El Mouraouah M. Benammi A. El Mouraouah A. Iben Brahim A. Birouk M. Kasmi 《Environmental Earth Sciences》2012,67(8):2411-2422
Combining the results from field observations, high resolution 2D-electric resistivity and high resolution seismic refraction tomography, we have found new evidence for active faulting in the Dhar Doum area, northwestern Atlantic coast of Morocco. Qualitative interpretation of the inverted resistivity and seismic refraction data reveals the presence of two thrust faults that cut the topographic surface and displace the most recent sedimentary deposits. Furthermore, one of these seismically imaged faults strongly correlates with the Dhar Doum?CLalla Zahra fault. The steepening at the surface and the flattening with depth of this fault are likely to indicate an important strike-slip component associated with a major reverse component. If extended offshore to the west, the Dhar Doum fault could be a continuation of the southernmost deformational front of the Cadiz oceanic accretionary prism. Therefore, this structure is very likely to represent the actual active southern deformational front of the oceanic accretionary prism, as well as that of the Rif fold-and-thrust belt. The southward thickening of the growth strata composing the uppermost dune system and the occurrence of Plio-Quaternary conglomerates north of the Dhar Doum?CLalla Zahra fault suggest that the neotectonic activity may have started by the end of the Pliocene and have continued to the present as indicated by the folding-and-faulting of the most recent sedimentary deposits and the presence of high scarps. The identification of active faulting in the study area that may have a profound influence on seismic hazard analysis of the whole Rif foredeep basin. 相似文献