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SummaryAs a feature of capitalist development, economic migration has historically entailed sex work as one of its components. In the age of globalization, this means a forced choice for many women, as they move from the village to the city in their own countries and across international borders. The present article focuses on the decision making process, the means of migration, and the experience in the urban site, national or international, of those -- the vast majority -- who have not been "trafficked", but have made this forced choice their life strategy. The impact on sex worker migration of customer "migration" in the form of sex tourism is discussed, along with the other economic and cultural factors.

AbstractThe authors present a discussion of teachers' pedagogical culture as related to characteristics of multicultural classes. They examine the socio-political issues regarding multicultural classes, the process for training teaching practices, and the role given to learning the language of the host country. This analysis is based on a sociologist's interviews of teachers and on an analysis of ministerial reports describing schooling levels of allophones in France. The findings point out that the socio-cultural origin of teachers and the educational practices of the socio-institutional system provide the foundations for the construction of pedagogical practices, and, if mastery of the language used for teaching influences school success for students from social and cultural minority groups, then the absence of an institutional legitimacy for other languages and cultures limits their school integration.

AbstractThis article examines a program which integrates music into the curriculum for French as a second language as well as the influence of this on learning music and French. Classroom teachers experimented a program of "music-language" whose objective was the learning of melody-rhythm patterns and musical form which provided similarities to oral and written comprehension and production in French. The sample included six classes of Grade 2 children in French immersion in New Brunswick : a control group (n=64) and an experimental group (n = 63). All subjects were administered pre and post tests. Application of ANOVA and ANCOVA statistical procedures revealed significant differences between the two groups on music tests and in oral and written French tests.

AbstractThe Saguenay–St. Lawrence Marine Park (PMSSL) is located in one of the most productive areas of the St. Lawrence and supports large numbers of aquatic birds all year round. Nevertheless, there is no detailed study on the use of this area by aquatic birds in winter. So, to rectify the situation, aerial and ground surveys were done to better quantify the distribution, abundance and behaviour of aquatic birds wintering in the PMSSL. Results confirm the importance of the PMSSL for aquatic birds wintering in the St. Lawrence estuary, and establish that birds move within the PMSSL in relation to tides, ice conditions and winds. The most numerous waterfowl species are the Long-tailed Duck (Clangula hyemalis), the Red-breasted Merganser (Mergus serrator), the Common Goldeneye (Bucephala clangula), the Barrow's Goldeneye (B. islandica) and the Black Duck (Anas rubripes). Four species of gulls winter there in great numbers: the Arctic Gull (Larus glaucoides), the Glaucous Gull (L. hyperboreus), the Herring Gull (L. argentatus) and the Great Black-backed Gull (L. marinus). Black Guillemots (Cepphus grylle) were also present offshore, as well as Purple Sandpipers (Calidris maritima) on the offshore islands and shoals, and a small number of Buffleheads (Bucephala albeola). Christmas Bird Count Data suggest an increase in wintering populations of Black Ducks, Mallards (Anas plathyrynchos), Barrow's Goldeneyes and Red-breasted Mergansers. However, large flocks of Long-tailed Ducks have been less frequent in recent years.

Keywords: Oiseaux aquatiques, canards, goélands, garrots, Canards noirs, hiver, Harelde kakawi, inventaires, Aquatic birds, ducks, gulls, Goldeneye, black ducks, winter, long-tailed duck, surveys

This paper presents an overview of physically-based hydrological modeling approaches and a look at the future of hydrological modeling within the context of water management. It extends beyond classical hydrological modeling by surveying the modeling of water contaminants transport in porous media and surface waters, as well as soil erosion.Increasing concerns in predicting the impacts of land use management on the hydrological cycle have led researchers to construct two types of physically-based distributed models. The first type of model views the watershed as an ensemble of inter-connected reservoirs and mimics water routing with various types of discharge expressions and conceptual models (e.g., the infiltration models of Green and Ampt (1911), Holtan (1961) or Smith and Parlange (1978); the unit hydrographs of Sherman (1932) and Dooge (1973) and the geomorphological unit hydrograph of Rodriguez-Iturbe and Valdes (1979); the ground water discharge model of Beven and Kirby (1979); etc...). It is noteworthy that the pioneering Stanford Watershed Model of Crawford and Linsley (1966) led to the development of many currently used hydrological models including HBV (Bergstršm and Forsman, 1973), SLURP (Kite, 1978), TOPMODEL ( Beven and Kirby, 1979) and CEQUEAU (Morin et al., 1981), to name a few. The second type of model discretizes the watershed into an ensemble of control volumes and mimics water routing using combinations of partial differential equations for mass and momentum conservation and phenomenological models (e.g., Darcy's (1856), Dupuit's (1863), Boussinesq's (1904) and Richards (1931) equations for unsaturated and saturated flow in porous media; Saint-Venant's (1871) and Manning's (1891) equations for overland and open channel flows). Hydrological models such as SHE (Abbott et al.,1986a, b), IHDM (Calver, 1988), KINEROS (Woolhiser et al., 1990), THALES (Grayson et al.,1992) and HYDROTEL (Fortin et al., 1995), among others, represent classical examples of this type of modeling. It is noteworthy that recent advances in remote sensing and in digital elevation modeling have greatly facilitated and simplified the use of most of the hydrological models.On another front, the adverse effects of agricultural, industrial and urban runoff on surface and ground waters have motivated the development and application of different approaches to predict the fate and transport of various water contaminants in the environment (i.e., eroded soil particles, adsorbed and dissolved nutrients and pesticides as well organic matter).In soil erosion modeling, these concerns have led researchers to construct nonpoint source pollution models for evaluating the impacts of alternative land management practices on water quality. Based on the empirical Universal Soil Loss Equation (Wischmeier and Smith, 1978), the first nonpoint source models included CREAMS (Knisel et al., 1980), AGNPS (Young et al., 1987) and SWRRB (Williams et al., 1985). However, the lack of physical realism in these empirical formulations prompted the development of physically-based erosion models such as GUEST (Rose et al., 1983; Hairshine and Rose, 1992a, b), WEPP (Nearing et al., 1989), LISEM (De Roo et al., 1994) and EUROSEM (Morgan et al., 1992). The advantage of these models over the USLE resides in their ease of integration with physically-based hydrological models. Because of its close ties with the hydrological cycle and the soil erosion process (adsorbed and dissolved contaminants), the development of physically-based models for nutrient and pesticide transport benefited directly from advances in soil erosion modeling, soil chemistry and soil physics. The modeling of nitrogen transport is a representative example of this. Early modeling efforts involved the coupling of first-order kinetics models for the nitrogen cycle (Mehran and Tanji, 1974) with two types of mass conservation equation in porous media: the convection-dispersion equation and the capacity transport equation. Well known soil nitrogen dynamics models include NCSOIL (Molina et al., 1983), SOILN (Johnsson et al, 1987), EPIC (Sharpley and Williams, 1990), LEACHN and LEACHA (Hutson and Wagenet, 1991, 1992, 1993), DAISY (Hansen et al., 1991) and AgriFlux (Banton et al., 1993).The first attempt to model surface water quality goes back to the work of Streeter and Phelps (1925) who studied the impacts of a municipal waste water discharge on dissolved oxygen (DO) and biological oxygen demand (BOD) of an Ohio river. To predict DO and BOD dynamics, Streeter and Phelps assumed uniform and steady flow conditions and used first-order kinetics to model atmospheric supply of oxygen and oxygen consumption. The advances in computational power during the 70s and 80s allowed several researchers to substantially increase the complexity of the Streeter-Phelps approach. This was achieved by accounting for advection-dispersion phenomena, unsteady two and three dimensional flow conditions, as well as the effect of temperature on various chemical reactions. The QUAL2E model of Brown and Barnwell (1987) is a good example of a moderately complex water quality model where advection-dispersion and temperature effects on several water characteristics and contaminants are considered under one-dimensional steady flow conditions.At present, the state of hydrological modeling and software engineering has reached a point where it is now possible to construct spatial decision support systems (SDDS) capable of simulating the impacts of various management practices (i.e., industrial, municipal and agricultural) on the water quantity and the quality of a watershed's river network. These systems, which idealy should be user-friendly for decision makers, will be both integrated modeling systems (including a database system, hydrologic, soil erosion, agricultural-chemical transport and water quality models) and spatial data analysis systems (including a geographical information system). Currently developed SDDS include PÉGASE (Smitz et al., 1997) and GIBSI (Villeneuve et al., 1996, 1997a,b). In a sustainable water management context, the use of such systems will provide decision makers with a complete tool for exploring a variety of integrated watershed management programs.

Keywords: Système de modélisation intégrée, érosion des sols, contaminants agricoles, qualité de l'eau, Integrated modeling system, soil erosion, agricultural contaminants, water quality

AbstractResearch on the ecology, biodiversity and toxicology of cyanobacteria in Moroccan inland waters has been carried out since 1994. The results demonstrate the existence of several taxa of cyanobacteria. Most of them are toxic, bloom‑forming species present in various water bodies of the country. The present study follows upon this earlier work and spans the 2003-2006 period. The major aim was to update and supplement the existing national cyanobacteria inventory and to isolate new toxic strains. During the study period, more than 40 aquatic environments were visited and sampled.Almost 300 taxa of cyanobacteria were recorded. They belonged to 3 orders, 14 families and 46 genera. Among these, about 78 taxa are recorded for the first time in Morocco; 29 strains of cyanobacteria were successfully isolated and cultured in the laboratory. All the collected cyanobacteria, including natural blooms, mats, and cultured strains, were analyzed for toxicity and hepatotoxins (microcystins) were quantified. Using the High-performance liquid chromatography technique coupled to photodiode array (PDA) detector (HPLC-PDA), four samples of Microcystis blooms showed the presence of microcystins (MCs), with a concentration ranging between 1.87 and 64.4 µg•g‑1 MC‑LR eq (microcystin-LR equivalents). A total of five different structural variants of MCs were detected (MC-LR, -RR, -YR, -FR, -WR). Furthermore, 3 of 29 isolates were confirmed as MCs producing strains.The results show that the widening of the survey led to a better knowledge of the diversity of cyanobacteria. The taxonomic inventory was greatly increased and several cyanobacteria strains were characterized for their toxicity. The results should be useful as a database for the identification of various aquatic environments contaminated by cyanobacterial toxins (microcystins), which represent a potent sanitary risk for human and animals.

Keywords: Cyanobacteria, taxonomy, microcystins, blooms, isolates, inland waters, Morocco, Cyanobactéries, taxonomie, microcystines, blooms, souches isolées, eaux continentales, Maroc

This study adopted a combined paleolimnological-limnological approach towards evaluating the trophic history of Lake Saint-Charles, the drinking water reservoir for a population of 305,000 in the Québec City (Canada) region. Our limnological measurements indicate that the lake is currently in a state of advanced mesotrophy. Water column profiles during late summer stratification (September) showed that the bottom waters were anoxic, enriched in phosphorus (up to 17 µg total P L-1) and had a pH almost 2 units lower than the surface waters. Surface phytoplankton concentrations were high at this time of year with Chlorophyll a concentrations of up to 12 µg·L-1. At the end of winter stratification, oxygen concentrations were below saturation at all depths, ranging from 72% immediately under the ice to 4% at the bottom of the water column. This tendency towards eutrophic conditions was offset, however, by a rapid flushing rate (mean hydraulic residence time=23 days). Because there are concerns that the lake has experienced accelerated nutrient enrichment due to increased human activities in its drainage basin, the objectives of our paleolimnological approach were to document the recent trophic history of this lake, to estimate the extent of recent changes in trophic status, and to identify critical periods of past anthropogenic disturbances from the fossils of siliceous algae (diatoms; class Bacillariophyceae) preserved in its sediments. Quantitative estimates of past total phosphorus (TP) concentrations in the water column of Lake Saint-Charles were obtained by applying a diatom-TP reconstruction model developed for 54 lakes located in south-eastern Ontario to fossil diatom assemblages from a 28 cm long sediment core. The timing of changes in the fossil diatom record was estimated by210 Pb dating. The study reveals changes in fossil diatom assemblage composition during the past ca. 150 years, with the most striking biological and physico-chemical changes occurring immediately after 1934. This date coincides with the construction of a dam, which raised the lake water level by 1.5-2 m. This modification was accompanied by significant shifts in diatom community structure, especially in the planktonic/benthic ratio (with increases in planktonic diatoms Cyclotella stelligera and Aulacoseira distans), and by changes in the physico-chemical characteristics of the sediments. Paleoproductivity increased at the same time, but remained more or less stable following conservation efforts between 1950 and 1970 (e.g., construction of a sewage treatment system). The organic matter content of the sediments showed an increase in the order of 20% between 1850 and 1950, after which it remained constant. Fossil diatom community structure indicates that mesotrophic conditions have prevailed during the recent history of Lake Saint-Charles, and that diatoms typical of eutrophic conditions never became established in the lake. The geochemical analysis of phosphorus in the sediments as well as the diatom-inferred quantitative reconstruction of lake water total phosphorus reveals a slight decrease in total phosphorus over time, from close to 17 µg·L- prior to 1887 to about 13 µg·L- 1 in recent times. These observations suggest that Lake Saint-Charles has not experienced significant recent changes in trophic status due to increased human activities in its drainage basin. However, our geochemical analyses show a sharp rise in metal concentrations (especially Fe, Mn, Cu, Pb and Zn), beginning in the late 19th century, reaching a plateau by the late 1970s, which may be attributed to increased atmospheric pollution since the beginning of intense human colonization in the lake's catchment and surrounding areas. This in combination with the advanced mesotrophic status of the lake indicates the ongoing need for careful management of the watershed to prevent further changes in this important urban water resource.

Keywords: Paléolimnologie, diatomées, phosphore total (PT), fonction de transfert, eutrophication, pollution, Québec, Paleolimnology, diatoms, total phosphorus (TP), transfer function, eutrophication, pollution, Québec

Research on the estimation of extreme precipitation events is currently expanding. This field of research is of great importance in hydraulic engineering not only for the design of dams and dikes, but also for municipal engineering designs. In many cases, local data are scarce. In this context, regionalization methods are very useful tools. This paper summarizes the most recent work on the regionalization of precipitation. Steps normally included in any regionalization work are the delineation of homogenous regions, selection a regional probability distribution function and fitting the parameters.Methods to determine homogenous regions are first reviewed. A great deal of work on precipitation was inspired by methods developed for regional flow analysis, especially the index flood approach. Homogenous regions can be contiguous, but in many cases they are not. The region of influence approach, commonly used in hydrological studies, has not been often applied to precipitation data. Homogenous regions can be established using multivariate statistical approaches such as Principal Component Analysis or Factorial Analysis. These approaches have been used in a number of regions in Canada. Sites within a homogenous region may be tested for their appropriateness by calculating local statistics such as the coefficient of variation, coefficient of skewness and kurtosis, and by comparing these statistics to the regional statistics. Another common approach is the use of L-moments. L-moments are linear combinations of ordered statistics and hence are not as sensitive to outliers as conventional moments. Other homogeneity tests have also been used. They include a Chi-squared test on all regional quantiles associated with a given non-exceedance probability, and a Smirnoff test used to validate the inclusion of a station in the homogenous region.Secondly, we review the distributions and fitting methods used in regionalization of precipitation. The most popular distribution function used is the General Extreme Value (GEV) distribution. This distribution has been recommended for precipitation frequency analysis in the United Kingdom. For regional analysis, the GEV is preferred to the Gumbel distribution, which is often used for site-specific frequency analysis of precipitation extremes. L-moments are also often used to calculate the parameters of the GEV distribution. Some applications of the Two-Component Extreme Value (TCEV) distribution also exist. The TCEV has mostly been used to alleviate the concerns over some of the theoretical and practical restrictions of the GEV.Applications of the Partial Duration Series or Peak-Over-Threshold (POT) approach are also described. In the POT approach, events with a magnitude exceeding a certain threshold are considered in the analysis. The occurrence of such exceedances is modelled as a Poisson process. One of the drawbacks of this method is that it is sometimes necessary to select a relatively high threshold in order to comply with the assumption that observations are independent and identically distributed (i.i.d.). The use of a re-parameterised Generalised Pareto distribution has also been suggested by some researchers.Research on depth-duration relations on a regional scale is also discussed. Empirical approaches used in Canada and elsewhere are described. In most cases, the method consists of establishing a non-linear relationship between a quantile associated with a given duration and its return period to a reference quantile, such as a 1-hour rainfall with a 10-year return period. Depth duration relationships cannot be applied uniformly across Canada for events with durations exceeding two hours. Seasonal variability studies in regionalization are relatively scarce, but are required because of the obvious seasonality of precipitation. In many cases, seasonal regimes may lead to different regionalization approaches for the wet and the dry season. Some research has focused on the use of periodic functions to model regional parameters. Another approach consists of converting the occurrence data of a given event in an angular measurement and developing seasonal indices based on this angular measurement.Other promising avenues of research include the scaling approach. The debate over the possibility of scale invariance for precipitation is ongoing. Simple scaling was studied on a number of precipitation data, but the fact that intermittence is common in precipitation regimes and the presence of numerous zero values in the series does not readily lead to proper application of this approach. Recent research has shown that multiple scaling is likely a more promising avenue.

A hill reservoir is a small lake resulting from a small dam. Hill reservoirs contain fifty thousand to one million m3 of runoff water from watersheds whose areas range from a few hectares to several km2. They are integrated in a natural way within the landscape and do not create any particular pollution problems. They regulate water flow and thus help to maintain populations in place, ensuring for them real possibilities of development. Their construction has several objectives:- protection of downstream infrastructures against floods and erosion ;- assuring availability of water at several places in the landscape for domestic needs, watering cattle, micro-irrigation, and water harvesting for refilling shallow groundwater reserves ;- development of new economic activities: irrigation, breeding, fishing and fish farming, tourism, and improvement of the environment (creation of oases, afforestation, etc.).The HYDROMED research project was undertaken in four countries (Lebanon, Morocco, Syria and Tunisia) where a strong policy favouring the building of small dam is going on in parallel to the construction of large dams.The goal of the HYDROMED project is to assess the impact of these hydraulic dams on the local environment and on lakeside rural communities.In addition to a training program and co-ordination activities, four projects were carried out:- Synthesis of existent data from each country and a choice of test sites for relevant experimentation ; - Characterization of the water and soil environment ;- Examination of agronomy, agricultural economy and the social management of water ;- Sustainability of the hill reservoir and its integration into sustainable development of marginal regions.After an analysis and synthesis of these projects in each country, seven test sites were chosen and a multidisciplinary approach was adopted.All small reservoirs at the test sites were equipped with a water level gauge, an evaporation pan, and two stations for automatic data collection. One station was connected to a tipping bucket rain gauge (0.5 mm rainwater), whereas the other was connected to probes that measured water and air temperatures and water levels with 1 cm accuracy. The spillways were shaped in such a way that discharge could be estimated. Since the beginning of the project, annual records of all observations made from September to August at these test sites have been published. A computerized bank of hydrological data was set up. The parameters describing the watersheds were also recorded in a similar data bank. Maps of different watersheds were stored using a geographical information system (GIS). The main objective of this work was to build a hydrological model suitable for semiarid Mediterranean catchments with hill reservoirs, with two specific objectives: (i) rainfall-runoff simulation and (ii) simulation of reservoir storage capacity and probability of failure. This model, called HYDROMED (RAGAB et al., 2001 a, b, c), provided the project with an accurate understanding of the water resource and allowed the evaluation of water availability for different uses.The bathymetry of each reservoir was measured at least once every two hydrological years, and was compared with a fine resolution land survey, making it possible to determine the rate of siltation in the pond, and to establish depth/volume and depth/surface curves. At the same time, studies on sheet erosion and gully erosion were carried out in the watersheds. Solid transport varied from 1.8 t/ha/an on a small forested catchment with soil conservation management (El Gouazine in Tunisia) to 50 t/ha/an on a cultivated catchment with marl in the Rif foothills (Morocco). A model was applied to compute the solid transport for each flood (ALBERGEL et al. 2003). It showed that solid transport is not a linear function of time and noted, for example, that 3 floods were responsible for 50% of the sedimentation that occurred in the Kamech dam (Tunisia) between the years 1994 and 2002.Water samples were collected seasonally during the project. Electrical conductivity (E.C.) and pH were measured and the concentrations in the major ions were determined (RAHAINGOMANANA, 1998). The geochemical characterization of the water in hill reservoirs showed three major groups: calcium sulphate water types, calcium bicarbonate dominated waters and sodium chloride dominated waters. The observations made during different hydrological periods aided in the understanding of the present geochemical evolution of water and confirmed the importance of reservoir hydrology in this evolution. Simulations with the Expreso model (RIEU et al., 1997) were used to estimate the risk of water quality deterioration due to evaporation.An agronomic survey was carried out in Tunisia on water requirements for the main cropping systems and for different irrigation systems (traditional, sprinkler or drip irrigation) on two semi-arid sites. At the catchment scale, measurements of energy balance showed a very strong water demand throughout the year. Values of potential evapotranspiration were always greater than 4 mm/day at Kamech (Cap Bon Peninsula) and greater than 5 mm/day at El Gouazine (Central Tunisia). During winter, high potential evapotranspiration values are due to strong winds. Micro-meteorological studies on rainfed agriculture allowed the estimation of actual evapotranspiration fluxes for hard wheat at both sites. The observed actual evapotranspiration of hard wheat (2.3 mm/day at Kamech and 1.9 mm/day at El Gouazine from mid-February to mid-May) was always less than potential evapotranspiration. Micro-meteorological measurements on a drip irrigated tomato crop showed an actual evapotranspiration rate of 6 to 7 mm/day in July for an irrigation height of 9 to 10 mm/day. Thermic stresses were observed in summer time when air temperatures exceeded 45°C (Vacher and Mougou, in HYDROMED 2001).Economic, social and environmental studies were made using surveys with the farmers. Access to water and social organizations were studied as well as the division of responsibilities among state, collectivities and the individual.The use of water in the hill reservoirs appeared to be limited, but variable from one lake to the other. On the Kamech site in Cap Bon the dam was equipped with 4 fuel water pumps. Intensive cultivation of drip-irrigated tomatoes and peppers (10 ha) coexists with traditional irrigated gardens.There is little to no exploitation of hill reservoirs that are far from the markets. Among other uses of the reservoir water, cattle watering and domestic needs were also important.In all semi-arid Mediterranean regions, ovine breeding is an important income for farmers.

Keywords: Méditerranée, eau, petits barrages, lacs collinaires, aménagements hydro agricoles, Mediterranean, water, small dams, hill reservoirs, rural hydraulic works

The aim of this study was to investigate the potential of a helophytic plant, Phragmites australis (Cav.) Steudel, to remove chromium from concentrated tannery effluent in comparison to unplanted soil, under arid climate conditions. The experiment was conducted from August 2002 to August 2003. Six plots (capacity: 120 L, diameter: 50 cm) were filled to depths of 15 cm and 60 cm with gravel and soil respectively (texture: 3.5% clay, 8.5% silt, and 88% sand). Three plots were planted with Phragmites australis (Cav.) Steudel. Young shoots of plants (36 stems/m2) were taken from local and natural reed stands. Three unplanted plots were used as controls. The soil for the study was from the Tensift River (Marrakech). The experimental plots were supplied exclusively with diluted tannery wastewater, 3 times a week (approximately 10 L each time). The water flowed vertically through the substratum.To investigate the capacity of the systems to increase pH, to decrease conductivity chemical oxygen demand (COD), and to remove total chromium, concentrations in the inflow and outflow of each plot were determined during the experiment. System hydrology indicated that for planted systems, the mean flow varied from 18 mL/min (in winter) to 49 mL/min (in summer), with an average value of 35 mL/min. For the unplanted system, the mean flow varied from 5 mL/min (in winter) to 15 mL/min (in summer) with an average value of 12 mL/min. Water recovery at the outflow of the planted system (PP) and unplanted system (NPP) was 40% and 60% respectively. This may be related to the phenomenon of evapotranspiration from the PP system, which was more significant than simple evaporation from the NPP system. No sign of clogging was observed in the planted systems due to the plant rhizomes that ensure a better aeration of the soil. The study of the hydrological operation showed that mean flow in the planted system was three times higher than that in the unplanted soil, which makes it possible to treat a larger volume of wastewater and to reduce the required per capita surface for treatment. The presence of Phragmites australis ensured a sufficient porosity for the percolation of water for treatment.The pH of the effluent at the outlets of the planted and unplanted systems increased by two to three units in comparison with the raw wastewater at the inlet. The average inflow pH was 5.5; at the outflow of the two systems, the pH was 7.30 and 8.20 respectively for the planted and unplanted soil. The electrical conductivity (EC) of the treated wastewater increased for the two systems. The average inflow conductivity was 54±5.5ms/cm. At the outflow of the two systems, the EC was about 75±14 ms/cm and 68±11 ms/cm respectively for the planted and unplanted systems. The EC removal for all systems varied significantly from season to another (p< 0.05).The planted system was more efficient in removing total COD (74%) than the unplanted one (61%). There were significant differences (ANOVA) between the PP and NPP systems (p<0.05). Total chromium concentrations at the inflow varied from 534 mg/L to 1000 mg/L with an average content of 780±196 mg/L. At the outflow, total chromium concentrations varied from 2.2 mg/L to 3 mg/L with an average content of 2±0.5 mg/L for the PP system and from 2.5 mg/L to 4 mg/L with an average value of 2.4±1.3 mg/L for the NPP system. Total chromium removal of 99% occurred for the two pilots, which provides limpid purified water. Despite the shorter retention time for the planted system, which was three times less than in the unplanted one, total chromium was almost completely removed.The aquatic macrophyte plant seemed to play a physical role by enhancing the hydrological conductivity of the substratum and consequently the operation and management of these systems. Phragmites australis (Cav.) Steudel has the ability to transfer oxygen from the rhizome towards the roots through an internal lacunar system, which offers the creation of an aerobic zone around the roots. This aerobic zone allows the proliferation of micro-organisms, which are the principal decomposers of the organic matter in the root zone.The treatment of tannery effluent by reed beds is a clean approach from an ecological point of view and constitutes a viable economic alternative in comparison to purely chemical approaches and is thus better adapted to the complexity of the systems used in the leather industry.

Keywords: Phragmites australis (Cav.) Steudel, climat aride, tannerie, rejet industriel, chrome, lits à roseaux, Phragmites australis (Cav.) Steudel, arid climate, chromium, tannery, industrial wastewater, reed beds