Impact des lixiviats de la décharge sauvage de la ville de Taza sur les ressources hydriques (Maroc)

La population de Taza, estimée à environ 154 496 habitants, produit 18 000 tonnes par jour de déchet solide et ceci malgré la faible activité industrielle de cette région. Ces déchets sont essentiellement domestiques(0,85 kg/ jours/ habitant) et sont réacheminés vers la décharge publique de Taza. Cette dernière est installée sur une plaine alluviale s’étendant sur une superficie de 4 hectares et n’ayant bénéficié, ni d’une étude  préliminaire géologique ni hydrogéologique ni d’impact. De plus, le site de la décharge est à 1,2 Km du centre de l'agglomération et au coeur de l'Oued Larbâa ce qui pourrait générer de sérieux problèmes de pollution.L’objectif du présent travail est l’étude de la qualité des eaux superficielles et souterraines pour évaluer le degré de pollution provenant des lixiviats de la décharge et des cours d’eaux dans lesquels les rejets des eaux usées de la ville sont directement déversés. Les résultats obtenus, sur la base d’analyse des échantillons, ont montré une dégradation plus ou moins forte de la qualité physico-chimique des eaux de la nappe  souterraine et des eaux de surface spécialement en aval de la décharge et la présence d’une contamination bactérienne des eaux de surface et souterraines.Mots-clés : décharge sauvage, lixiviats, pollution, physico-chimie, Taza

Evaluation de la pression d’utilisation phytosanitaire sur l’environnement : Cas du fraisier de Loukkos nord-ouest du Maroc

Modern agriculture relies on the intensive use of chemical inputs including pesticides. Unfortunately, the irrational and often abusive use of pesticides poses a threat to both human health and the environment through residues in foodstuffs and the pollution of the various compartments of the environment, in particular both surface and groundwater, especially since these practices and their impacts are poorly understood. Agri-environmental indicators represent a valuable tool for studying and assessing the pressure of phytosanitary use on the environment. Strawberry cultivation is highly developed in the Loukkos irrigated perimeter (north-west of Morocco) and is the subject of many phytosanitary interventions with regard to the phytosanitary problems of this crop. In this work, we assessed the impact of phytosanitary use of strawberry on the environment based on the determination of agri-environmental indicators. The methodology of the study is based on field surveys with 31 strawberry growers in the area using a questionnaire in which we gathered as much information as possible about the conduct and the technical route followed by the strawberry producers. The results showed that the agri-environmental indicators calculated on all the farms surveyed reveal very high values such as treatment frequency Index (IFT), Number of treatments (NT), Total quantity of active substances used (QSA) and Polluting pressure by pesticides (PPP). These results reflect the intensive use of pesticides, justified by high number of products used (32 CP, 29 A.I.) and by high average frequency of pesticide treatments (22) per production cycle. Indeed, the adoption of agri-environmental indicators is essential in order to follow the evolution of pesticides use and thus minimize pesticide treatments with the consequence of reducing the risks of contamination of natural resources as part of a strategy integrated pest management or agro-ecological respectful of the environment.L’agriculture moderne repose sur l’utilisation intensive des intrants chimiques notamment les pesticides. Malheureusement l’utilisation non rationnelle et souvent abusive des pesticides, présente une menace aussi bien pour la santé humaine que pour l’environnement à travers les résidus dans les denrées alimentaires et la poullution des différents compartiments de l’environnement notamment les eaux aussi bien superficielles que souterraines, d’autant plus que ces pratiques ainsi que leurs impacts sont mal connues. Les indicateurs agroenvironnementaux représentent un outil précieux pour étudier et évaluer la pression d’utilisation phytosanitaire sur l’environnement. La culture du fraisier est très développée dans le périmètre irrigué du Loukkos (nord-ouest du Maroc) et fait l’objet de beaucoup d’interventions phytosanitaires au regard des problèmes phytosanitaires de cette culture. Dans ce travail, nous avons évalué l’impact d’utilisation phytosanitaire du fraisier sur l’environnement en se basant sur la détermination des indicateurs agroenvironnementaux. La méthodologie de l’étude repose sur des enquêtes de terrain auprès de 31 fraisiculteurs du périmètre à l’aide d’un questionnaire dans lequel on a rassemblé le maximum d’informations concernant la conduite et l’itinéraire technique suivi par les producteurs de fraise. Les résultats trouvés ont montré que les indicateurs agroenvironnementaux calculés sur l’ensemble des exploitations enquêtées révèlent des valeurs très élevées tels qu’indicateur de fréquence de traitement (IFT), Nombre de traitement (NT), Quantité totale de substances actives utilisée (QSA) et la Pression polluante par les pesticides (PPP). Ces résultats traduisent le recours intensif aux produits phytosanitaires, justifié par le nombre élevé de produits utilisés (32 PC, 29 M.A.) et par la fréquence moyenne de d’interventions phytosanitaires élevée (22) par cycle de production. En effet, l’adoption des indicateurs agro-environnementaux s’avère indispensable afin de suivre l’évolution d’utilisation phytosanitaire et minimiser ainsi les interventions phytosanitaires avec comme conséquence de réduire les risques de contamination des ressources naturelles dans le cadre d’une stratégie de lutte intégrée ou agro écologique respectueuse de l’environnement

Low-voltage ride-through capability improvement of type-3 wind turbine through active disturbance rejection feedback control-based dynamic voltage restorer

Disconnections due to voltage drops in the grid cannot be permitted if wind turbines (WTs) contribute significantly to electricity production, as this increases the risk of production loss and destabilizes the grid. To mitigate the negative effects of these occurrences, WTs must be able to ride through the low-voltage conditions and inject reactive current to provide dynamic voltage support. This paper investigates the low-voltage ride-Through (LVRT) capability enhancement of a Type-3 WT utilizing a dynamic voltage restorer (DVR). During the grid voltage drop, the DVR quickly injects a compensating voltage to keep the stator voltage constant. This paper proposes an active disturbance rejection control (ADRC) scheme to control the rotor-side, grid-side and DVR-side converters in a wind-DVR integrated network. The performance of the Type-3 WT with DVR topology is evaluated under various test conditions using MATLAB®/Simulink®. These simulation results are also compared with the experimental results for the LVRT capability performed on a WT emulator equipped with a crowbar and direct current (DC) chopper. The simulation results demonstrate a favourable transient and steady-state response of the Type-3 wind turbine quantities defined by the LVRT codes, as well as improved reactive power support under balanced fault conditions. Under the most severe voltage drop of 95%, the stator currents, rotor currents and DC bus voltage are 1.25 pu, 1.40 pu and 1.09 UDC, respectively, conforming to the values of the LVRT codes. DVR controlled by the ADRC technique significantly increases the LVRT capabilities of a Type-3 doubly-fed induction generator-based WT under symmetrical voltage dip events. Although setting up ADRC controllers might be challenging, the proposed method has been shown to be extremely effective in reducing all kinds of internal and external disturbances

IMPACT ANTHROPIQUE SUR LA QUALITE DES EAUX SOUTERRAINES DU BASSIN VERSANT DE L’OUED TAZA (MAROC) ANTHROPOGENIC IMPACT ON GROUNDWATER QUALITY IN THE WATERSHED OF OUED TAZA (MOROCCO)

The main objective of this work is to determine the status of the groundwater quality in the watershed of Taza river, based primarily on physico-chemical and bacteriological parameters of groundwater. The Oued Taza is a small mountain river, 13.44 Km long, which drains a watershed of 40.07 km ². The outlet located at an altitude of 420 m corresponds to the confluence with the Oued Iarbaa. The average annual rainfall varies between 352 mm and 719mm while the annual average temperature is 18.1 ° C. Very high concentrations of nitrates, nitrites, heavy metals and bacterial load in some points near urban areas, illustrate the effect of human activities on degradation of water quality. This contamination could have several causes, the most important are related to household and industrial discharges (especially waters) spilled without any treatment in the rivers, and the use of fertilizers in agricultural areas. These results will enrich the database on water quality in the basin, and help policy makers to better decide on the management of water resources for a better sustainable development of the regio

THEORETICAL EVALUATION OF NONLINEAR EFFECTS ON OPTICAL WDM NETWORKS WITH VARIOUS FIBER TYPES

A theoretical study is carried out to evaluate the performance of an optical wavelength division multiplexing (WDM) network transmission system in the presence of crosstalk due to optical fiber nonlinearities. The most significant nonlinear effects in the optical fiber which are Cross-Phase Modulation (XPM), Four-Wave Mixing (FWM), and Stimulated Raman Scattering (SRS) are investigated. Four types of optical fiber are included in the analysis; these are: single-mode fiber (SMF), dispersion compensation fiber (DCF), non-zero dispersion fiber (NZDF), and non-zero dispersion shifted fiber (NZDSF). The results represent the standard deviation of nonlinearity induced crosstalk noise power due to FWM and SRS, XPM power penalty for SMF, DCF, NZDF, and NZDSF types of fiber, besides the Bit Error Rate (BER) for the three nonlinear effects using standard fiber type (SMF). It is concluded that three significant fiber nonlinearities are making huge limitations against increasing the launched power which is desired, otherwise, lower values of launched power limit network expansion including length, distance, covered areas, and number of users accessing the WDM network, unless suitable precautions are taken to neutralize the nonlinear effects. Besides, various fiber types are not behaving similarly towards network parameters

Laparoscopic diagnostic peritoneal lavage (L-DPL): A method for evaluation of penetrating abdominal stab wounds

BACKGROUND: The management of penetrating abdominal stab wounds has been the subject of continued reappraisal and controversy. In the present study a novel method which combines the use of diagnostic laparoscopy and DPL, termed laparoscopic diagnostic peritoneal lavage (L-DPL) is described METHOD: Five trauma patients with penetrating injuries to the lower chest or abdomen were included. Standard videoscopic equipment is utilized for the laparoscopic trauma evaluation of the injured patient. When no significant injury is detected, the videoscope is withdrawn and 1000 mL of normal saline is infused through the abdominal trochar into the peritoneal cavity, and the effluent fluid studied for RBCs, WBC, amylase debry, bile as it is uced in regular diagnostic peritoneal lavage RESULTS: Laparoscopic peritoneal lavage (L-DPL) was then performed and proved to be negative in all 5 patients. RBC lavage counts above 100,000/mcrl were not considered as a positive lavage result, because the bleeding source was directly observed and controlled laparoscopically. All patients recovered uneventfully and were released within 3 days. This procedure combines the visual advantages of laparoscopy together with the sensitivity and specificty of DPL for the diagnosis of significant penetrating intra-abdominal injury, when the diagnostic strategy of selective consevatism for abdominal stab wounds is adopted. CONCLUSION: A method of laparoscopic diagnostic peritoneal lavage (L-DPL) in hemodynamically stable patients with penetrating lower thoracic or abdominal stab wounds is described. The method is especially applicable for trauma surgeons with only basic experience in laparoscopic technique. This procedure is used to obtain conclusive evidence of significant intra-abdominal injury, confirm peritoneal penetration, control intra-abdominal bleeding, and repair lacerations to the diaphragm and abdominal wall. The combination of laparoscopy and DPL afforded by the L-DPL method adds to the sensitivity and specificity of DPL, and avoids under or over sesitivty, that have limited the use of DPL in the hemodynamically stable trauma patients with suspicious or proven peritoneal penetration