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Major solute concentrations in overland flow water (OFW) were measured in an agricultural field of Brittany (western France). Two storm events were monitored in detail to examine the short time‐scale processes. During one year, samples were taken at different positions on the slope after each storm event to describe the spatial and seasonal variations of OFW chemistry. Although the total dissolved load in OFW is not much higher than in rain water, distinctive features are observed. K+, Ca2+, NH4 , Cl− and SOare the major solutes. The main origin of the elements (sea salts, exchangeable soil complex or fertilizers) determined most of the variations observed. Spatial variations along the slope are mainly seen for exchangeable cations, while seasonal variations are predominant for sea salts. Rainfall intensity and suspended sediment load induce strong differences between the two storm events studied in detail. However, the within‐storm variations and the seasonal monitoring show that this relationship is complex. Within‐storm variations suggest that, in addition to desorption processes, mixing with pre‐event water may occur. The lack of a relationship between sediment load and dissolved load is attributed to the high rate of the exchange processes, which has been checked by a simple experiment in vitro. It is concluded that the conditions of the transit of water on the field (velocity, length, status of the surface, crusted or not) may well play a major role in the chemical changes between rain water and OFW. The results suggest that vegetated buffer strips designed to reduce the sediment load only, and not the amount of overland flow, will have little effect on the transfer of dissolved pollutants to the watercourses. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
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Djilali Berkane Hakima Harichane Zamila Çelebi Erkan Elachachi Sidi Mohammed 《地震工程与工程振动(英文版)》2019,18(3):497-509
The goal of this study is to provide a stochastic method to investigate the effects of the randomness of soil properties due to their natural spatial variability on the response spectra spatial variation at sites with varying conditions. For this purpose, Monte Carlo Simulations are used to include the variability of both incident ground motion and soil parameters in the response spectra by mean of an appropriate coherency loss function and a site-dependent transfer function, respectively. The approach is built on the assumption of vertical propagation of SH type waves in soil strata with uncertain parameters. The response spectra are obtained by numerical integration of the governing equation of a single-degree-of-freedom(SDOF) system under non-stationary site-dependent and spatially varying ground motion accelerations simulated with non-uniform spectral densities and coherency loss functions. Numerical examples showed that randomness of soil properties significantly affects the amplitudes of the response spectra, indicating that as the heterogeneity induced by the randomness of the parameters of the medium increases, the spectral ordinates attenuate. 相似文献
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Mehani Youcef Benouar Djilali Bechtoula Hakim Kibboua Abderrahmane 《Natural Hazards》2011,59(1):529-551
Algeria is a country with a high seismic activity. During the last decade, many destructive earthquakes occurred, particularly
in the northern part, causing enormous losses in human lives, buildings, and equipments. In order to reduce this risk in the
capital and avoid serious damages to the strategic existing buildings, the government decided to invest in seismic upgrade,
strengthening, and retrofitting of these buildings. To do so, seismic vulnerability study of this category of buildings has
been considered. Structural analysis is performed based on a site investigation (inspection of the building, collecting data,
materials characteristics, general conditions of the building, etc.) and existing drawings (architectural plans, structural
design, etc.). The aim of these seismic vulnerability studies is to develop guidelines and a methodology for rehabilitation
of existing buildings. This paper presents the methodology followed in our study and summarizes the vulnerability assessment
and strengthening of one of the strategic buildings according to the new Algerian Seismic Design Code RPA 99/version 2003.
As a direct application of this methodology, both static equivalent method and nonlinear dynamic analysis are performed and
presented in this paper. 相似文献
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As large destructive seismic events are not frequent in Algeria, anexhaustive knowledge of the historical seismicity is required to have arealistic view of seismic hazard in this part of the world. This research workpresents a critical reappraisal of seismicity in the north-eastern Algeria forseismotectonic and seismic hazard purposes. This part of work focuses onthe seismicity of pre-1900 period for the area under consideration[33°N-38°N, 4°E-9.5°E]. By going back tothe available documentary sources and evaluating and analysing the eventsin geographical, cultural and historical context, it has been possible toidentify 111 events, from 1850–1899, which are not reported in therecent Algerian catalogue. Several spurious events, reported in standardlistings, have been deleted and nine unknown events have been discovered.It is quite clear that macroseismic information derived from press reportsand published documents in Algeria, under certain conditions, is veryincomplete, even for destructive earthquakes, located in the countrysideaway from communication centres. One of the reasons for this iscensorship, noticeable during the colonisation period. Critical analysis ofnewly collected information has allowed the determination and/or theimprovement of the macroseismic parameters of each event, such aslocation, maximum epicentral intensity and magnitude to produce anearthquake catalogue as homogeneous and complete as the available data,for the zone under study. The criteria used in this research are explainedand eight historical earthquakes have been the subject of retrospectivemacroseismic field construction.The investigation of historical earthquakes is one of the most important taskin studying seismotectonic for seismic hazard evaluation purposes. 相似文献
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A. Mendas A. Delali M. Khalfallah L. Likou M. A. Gacemi H. Boukrentach A. Djilali R. Mahmoudi 《Arabian Journal of Geosciences》2014,7(2):435-445
The weighted sum already incorporated into a geographical information system (GIS) makes it possible to identify the best lands useful for sustainable agriculture. However, it does not allow for the inclusion of the decision makers’ preferences so that a choice can be made when there are conflicts between decision makers. Because of their spatial aggregation functions, multicriteria decision analysis methods can facilitate decision making in situations where several solutions are available, various criteria have to be taken into account, and decision makers disagree about one point or another. Combinations between ArcGIS and multicriteria analysis methods in this case Elimination Et Choix Traduisant la Realité (ELECTRE TRI) and a version of the weighted sum method simple additive weighting, applicable to the vector data model, have been established. The parameters and the classification system of Food and Agriculture Organization are used in this work. This approach has been tested on the area of Mleta in Algeria. Land suitability maps for durum wheat have been produced. Through the comparison between results obtained by these two methods and those available in a classical method, based on manual overlay procedures, it appears that optimistic procedure of the ELECTRE TRI method is better suited to the problem of land suitability for agriculture. 相似文献
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