Assessment of Surface Water Quality using Indices and Geographic Information System in the Sebou River Basin, Morocco

The aim of this study is to access the quality of monitored rivers and to map the polluted river sections in the Sebou basin using Geographic Information System (GIS). The potential causes of water quality variation will also be added for suitable measures to be taken. A Water Quality Index (WQI) which developed in Morocco was applied to 17 river water quality monitoring stations with data on 6 parameters (Dissolved oxygen (DO), ammonium ion (NH4 + ), 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), fecal coliforms (FC) and total phosphorus (TP)) collected twice during the wet and dry season over 1990-2017 period. The result shows that river water quality is classified as bad, very bad and medium at 59% of the monitoring stations, while 41% are considered as good to excellent. Interpolation of mean values of overall WQI of the 17 river water quality monitoring stations, revealed evidence of quality degradation along several kilometers of most river sections in the Sebou basin. The correlation matrix between the sub-indices of water quality parameters and the overall WQI showed high positive correlation coefficients and highlights the contribution to water quality degradation as follows: TP ( = +0.96 ) ≥ NH4 + ( = +0.96 ) > BOD5 ( = +0.94) > COD ( = +0.86) > FC ( = +0.83) > DO ( = +0.79). The sections of Fès, Innaounene Rivers, and an extended stretch of Tizguit River must no longer be used for irrigation. River water quality is overall of better quality in the wet season compared to the dry season. Simple linear regressions between the seasonal water quality variation and the overall WQI showed higher coefficients of determination R 2 (0.67 and 0.60) between dry season WQI and the overall WQI and between wet season WQI and the overall WQI respectively. It is clear that discharges of industrial and domestic wastewater during the dry season and agricultural activities are most likely to be the causes of the degradation of river water quality

Estimation Of Runoff And Erosion Rates Using Agwa - Kineros2 Model: Application To A Mediterranean Watershed

The Mediterranean area is classified as a region highly threatened by water erosion, which depends largely on climatic aggressiveness, erodible soils, sparse vegetation, and irrational human activity. Tleta watershed belongs to a young mountain ridge (Rif), readily erodible and highly vulnerable to water erosion. To assess the extent of this phenomenon, AGWA tool coupled with KINEROS2 (K2) model was used to predict the specific degradation and the hydrological functioning of the studied watershed. The data required consisted of topography, land use, soil type, and precipitation. The model simulations will make it possible to estimate the sediment load deposited at the Ibn Batouta dam, which results from upstream erosion. The evaluation criteria for the predictive skill of K2 model when comparing observed and simulated data are the coefficient of determination (R2) and the Nash–Sutcliffe model efficiency coefficient (NSE). These two coefficients are respectively (R² = 0.99, NSE = 0.71) and (R² = 0.99, NSE = 0.72) for runoff and sediments yield for calibration. For the validation process, these two coefficients are (R² = 0.99 and NSE = 0.98) for runoff and (R² = 0.99 and NSE = 0.97) for sediments yield. This allows us to conclude that the predictive accuracy of the model is promising

Integrated Water Resources Vulnerability Assessment: A Multidimensional Approach and Geographic Information System Based in Fès, Meknès, and Ifrane Perimeters, Morocco

Water resources are disproportionately distributed, and more and more problems related to this precious resource are being reported around the world due to anthropogenic pressures and global environmental changes. This paper focuses on assessing the vulnerability of water resources in an integrated way, by taking into account hydrological, environmental, socio-economic and pollution factors, in order to delineate sensitive areas of water resources under a geographic information system. The framework for assessing the water resources vulnerability in the Fès, Meknès, and Ifrane perimeters was based on a participatory approach through a survey. The data collected on the identified factors are then processed under ArcGIS tool to aggregate the normalized value into a water resources vulnerability index. The result shows that the degree of vulnerability of water resources in most of the study area is considered to be at the "threshold" to "non-vulnerable". However, three (3) main areas were considered to be "moderately vulnerable" to "highly vulnerable" precisely in the South of the city of Meknes (Zone 1), from the West of the city of Fès (Zone 2), and finally the Dayet Ifrah area (Zone 3). The sensitivity analysis showed that five factors have more impact on the overall water resources vulnerability map: topography, poverty, water withdrawal, population density, and access to drinking water. The result of this study could help integrated water resources management planners take action to improve the overall water quantity and quality in the area, and it can be extended to a larger scale like regional, national or cross-country

Modelisation Du Risque D’érosion Hydrique Par L’équation Universelle Des Pertes En Terre Dans Le Rif Occidental: Cas Du Bassin Versant De Moulay Bouchta (Maroc)

Soil erosion causes many environmental and socio-economic problems: loss of biodiversity, decrease in the productivity of agricultural land, siltation of dams and increased risk of flooding. It is therefore essential to establish a detailed evaluation of this process before any spatial planning. To evaluate the effects of soil erosion spatially and quantitatively in order to face this phenomenon, and propose the best conservation and land development strategies, the Universal Soil Loss Equation (USLE) coupled with a geographic information system (GIS) is applied. This model is a multiplication of the five erosion factors: the erosivity of the rain, the erodibility of the soil, the inclination and the slope length, the vegetation cover and the anti-erosion practices. The study area is the Moulay Bouchta watershed (7 889 ha), which is located in the western part of the Rif Mountains, is characterized by a complex and contrasting landscape. The resulting soil loss map shows an average erosion rate of 39.5 (t/ha/yr), 87% of the basin has an erosion rate above the tolerance threshold for soil loss (7 (t/ha/yr)). Soil losses per subbasin range from 16.2 to 81.4 (t/ha/yr). The amount of eroded soil is estimated at 311,591 (t/yr), corresponding to a specific degradation of 12.1 (t/ha/yr). In the absence of any erosion control, 25% of the soil losses would reach the new dam located a little upstream of the basin outlet, reducing its water mobilization capacity to 59,625 (m3/yr). The application of Principal Component Analysis (PCA) to soil erosion factors shows a significant influence of topographic factor (LS) on soil erosion process, followed by the effect of support practices (P), then by soil erodibility (K)

Drought characterization: A systematic literature review

This study examined the worsening severity of global droughts caused by climate change. However, the multiple definitions and varied range of drought indices pose challenges in effectively monitoring and assessing the prevalence and severity of droughts. This study aims to give a comprehensive overview of the various drought definitions found in the literature and how they have evolved based on their applications. Specifically, the focus was to shed light on the dynamic nature of drought characterization and offer insights into the factors that shaped its conceptualization over time. Within this context, this study explored three primary categories of drought indices: climatic, remote sensing, and composite. Each category was discussed in relation to its utility in specific fields, such as meteorological, agricultural, and hydrological drought assessments, along with an analysis of their strengths and limitations. Furthermore, this study presents modified meteorological drought indices that have been adapted to better monitor agricultural droughts. Additionally, the authors used geographic information systems to create a map showing the distribution of drought-related publications globally over the past decade. The findings showed that countries with arid and semi-arid climates are more actively involved in drought research, highlighting their particular interest and concern regarding the subject matter. The implications of this study emphasize the urgent need for immediate and coordinated efforts to address the escalating issue of droughts caused by climate change. By improving monitoring and assessment methods and focusing on tailored strategies in vulnerable regions, it is possible to mitigate the far-reaching consequences of drought and to build more resilient communities and ecosystems

Cartographie Du Risque De Salinité Des Sols À L’aide De L’approche Des Indices Et Des Données Multi-Sources: Cas De La Plaine De Tadla Au Maroc

La salinisation est l’une des formes de dégradation des sols qui connait une extension spectaculaire et qui révèle des aspects de plus en plus inquiétants. Elle contribue à la diminution de la production agricole dans la plupart des zones irriguées du monde, notamment celles soumises à un climat aride ou semi-aride. Ce phénomène résulte des effets synergiques du climat, de la roche mère, de l’agressivité des conditions naturelles et des activités anthropiques. Dans ce contexte, la présente étude se fixe comme objectif de cartographier le risque de salinité des sols de la plaine de Tadla. Pour atteindre cet objectif, nous avons adopté l’approche de l’Indice de Risque de Salinisation des Sols (IRSS) calculé à l’aide des données multi-sources (pédologiques, climatiques, hydrologiques et de salinité). La superposition des variables mises en jeu (la conductivité électrique de l’eau de nappe, la conductivité électrique de l’eau d’irrigation, la conductivité électrique du sol, la profondeur de la nappe, l’indice d’aridité, le type de climat, la pente, la texture et l’efficacité géologique) et leur pondération ont été réalisées à l’aide des SIG. Cette opération a permis de calculer l’indice IRSS et d’élaborer la carte de risque de salinité des sols de la zone d’étude. Cette approche basée sur l’IRSS a montré la présence de trois classes de risque de salinisation : léger, modéré et sévère. La classe de risque modéré domine avec une couverture de 76% de la superficie totale. Les résultats obtenus montrent l’intérêt de cette approche pour déterminer les zones à risque de salinisation afin de mieux gérer le risque de la salinisation des sols et réduire les effets de celle-ci sur la production agricole. Salinization is one of the forms of soil degradation that is expanding dramatically and is revealing increasingly worrying aspects. It contributes to the decline in agricultural production in most of the world's irrigated areas, especially those subject to arid or semi-arid climate. This phenomenon is the result of the synergistic effects of climate, bedrock, the aggressiveness of natural conditions and anthropogenic activities. In this context, the present study focuses on the mapping of salinity risk in the soils of Tadla Plain. To achieve this objective, we adopted the approach of the Soil Salinity Risk Index (SSRI) calculated using data from multiple sources (pedological, climatic, hydrological and salinity). The necessary variables (electrical conductivity of groundwater, electrical conductivity of irrigation water, electrical conductivity of soil, depth to groundwater, aridity index, climate type, slope, texture and geological efficiency) were overlaid and weighted using GIS. This operation allowed to calculate the SSRI and develop the soil salinity risk map of the study area. The use of the SSRI-based approach indicates the presence of three risk classes: light, moderate and severe. The moderate risk class dominates with a coverage representing 76% of the total area. The results obtained show the prospect of this approach to delineate areas of salinization risk to manage soil salinization and reduce its effects on agricultural production

Évaluation des coûts de la dégradation des sols agricoles par l’érosion hydrique: Cas du Bassin versant "Tleta"

This paper proposes an appraisal of costs produced by water erosion within arable lands strongly exposed to erosion in the catchment area of Tleta, located in the Rif, in the north of Morocco. Adopted methodology is inventive as allows to distinguish the costs according to three severity levels of erosion while taking into account the compensatory contributions, often invisible, of adaptation measures implemented by farmers. The differences between the gross margins obtained in three zones, classified according to the intensity of erosion, are compared two to two. The ensuing losses of benefit for each degree of severity of water erosion are deduced from the discrepancies observed in relation to the slightly degraded zone. The opportunity costs of outstanding lab or resulting from the community mutual aid, identified as a current practice in the basin studied to mitigate the damage of erosion, are also estimated in each zone. The estimates obtained are extrapolated to the whole cereal area of the basin to determine the total cost engendered by water erosion. Key-words: Economic appraisal, degradation costs, water erosion, benefits loss, soil conservation, erosion cost, Rif, Morocco  Le présent article propose une évaluation des coûts produits par l’érosion hydrique au sein des terres agricoles fortement exposées à l’érosion dans le bassin versant Tleta situé dans le Rif, au nord du Maroc. La méthodologie adoptée est originale et permet de distinguer les coûts en fonction de trois niveaux de sévérité de l'érosion tout en prenant en compte les apports compensatoires, souvent invisibles, des mesures d'adaptation mises en œuvre par les agriculteurs. Les écarts entre les marges brutes obtenues dans trois zones, classées selon l'intensité de l'érosion, sont comparés deux à deux. Les pertes de bénéfices conséquentes à chaque degré de sévérité de l'érosion hydrique sont déduites des écarts observés par rapport à la zone faiblement dégradée. Les coûts d'opportunité du travail non rémunéré issu de l'entraide villageoise, identifiée comme pratique courante au niveau du bassin étudié pour pallier les dégâts de l'érosion, sont également estimés dans chacune des zones. Les estimations obtenues sont extrapolées à l'ensemble de la sole céréalière du bassin versant pour estimer le coût total produit par l'érosion hydrique. Mots clés : Évaluation économique, coûts de la dégradation, érosion hydrique, perte de bénéfices, conservation des sols, coûts de l'érosion, Rif, Maro

Characterization of soil specific degradation for the northern region of Morocco

L’érosion hydrique est un processus majeur de dégradation des sols. Au Maroc, elle est considérée comme la principale cause de désertification. Elle entraîne une réduction du potentiel productif des sols et l'envasement des retenues de barrages conduisant à une perte du volume d'eau mobilisable et remettant en cause la durabilité de ces ouvrages hydrauliques. Des effets négatifs sont répercutés dans les domaines de la production de l'énergie électrique, de l'approvisionnement en eau potable et de l’irrigation. Face à l’ampleur de ce fléau, le Maroc doit multiplier ses interventions pour évaluer les conséquences de la dégradation des sols et mettre au point des programmes de conservation appropriés. Dans ce contexte, un échantillon de 15 barrages localisés au niveau de la région septentrionale du Maroc a été sélectionné en vue d’analyser l’envasement sur des périodes de 8 à 47 ans. Les données bathymétriques ont été fournies par la DRPE (Direction de la Recherche et de la Planification de l’Eau). Le présent papier a pour objectifs de i) caractériser la Dégradation Spécifique (DS) de la région septentrionale du Maroc à travers l'étude de 15 bassins versants ; ii) d'en déduire une gamme de variabilité de la DS dans cette région et iii) d'évaluer la pertinence de modèles simples basés sur la surface du bassin, ou la combinaison de la surface et de la lame écoulée moyenne annuelle, pour prédire la DS.L’approche adoptée repose sur la confrontation d'une mesure actualisée de la Dégradation Spécifique (DS) dérivée des levés bathymétriques avec des évaluations de cette dernière à l'aide de modèles établis pour prédire l’envasement des barrages au Maroc. L’analyse de l’alluvionnement des retenues de barrages par le dépouillement des levés bathymétriques sur des périodes allant de 8 à 47 ans montre un envasement total moyen annuel d’environ 0,6*109 m3, soit 13 % de la capacité totale initiale qui est de l’ordre de 4,6*109 m3 et une variabilité de la dégradation spécifique allant de 172 à 5365 t km-2an-1, soit un rapport de 1 à 31. Enfin, cette étude montre la très forte variabilité des performances de prédiction de la dégradation spécifique basées sur des modèles simples utilisant la surface de bassin et la lame écoulée. Mots clés : Érosion hydrique, Barrages, Envasement, Dégradation Spécifique, MarocWater erosion is a major process of soil degradation. In Morocco, it is regarded as the principal cause of desertification. It involves a reduction of the production potential of soils and as the silting of dam reservoirs leading to a loss of the amount of mobilizable water and brings up the issue of resilience of these hydraulic infrastructures. Adverse effects are reflected in the domains of energy production and irrigation and drinking water supplies. To face this challenge, Morocco must multiply its interventions to assess the consequences of soil degradation and to develop suitable programs of soil conservation. In this context, a sample of 15 catchment area located in the northern part of Morocco was selected in order to analyze the silting over periods of 8 to 47 years. The bathymetric data was provided by the DRPE (Direction of the Research and the Planning of Water).This paper aims i) to characterize the Specific Degradation (DS) of the northern part of Morocco through the study of 15 catchment areas; ii) to deduce a range of variability from the DS in this area and iii) to assess the relevance of simple models based on basin area, or the combination of basin area and the annual average flow, to predict the DS. The adopted approach is based on the confrontation of a current measurement of the Specific Degradation (DS) derived from the bathymetric surveys with assessments of the latter using models established to predict the silting of dams in Morocco. The analysis of siltation in dam reservoirs by the investigation of bathymetric data over periods from 8 to 47 years, shows an annual average total silting of approximately 0.6*109 m3, that is13% of the initial total capacity which is about 4.6*109 m3 and a variability of the specific degradation ranging from 172 to 5 365 tkm-2yr-1, that is a ratio of1 to 31. To end with, this study shows a significant variability of the performances of prediction of specific degradation based on simple models using the area of watershed and water flow. Key words: Water erosion, Dams, Silting, Specific degradation, Morocc

Techniques de conservation des eaux et des sols au Maroc: Aperçu et perspectives

The natural fragility of the environment (relief with steep slopes, aggressive rain, fragile substrates) associated with human fragility (poverty, insecurity) lead to the development and the extension of soil degradation. Water erosion concerns all Moroccan mountains and affects land productivity. This has prompted farmers to design and implement land management techniques, which optimize water use and promote rainwater harvesting. Land management institutions in these areas have also carried out soil protection and restoration (DRS) and soil and water conservation (SWC) projects for the same purposes. This study aims to inventory most of soil and water conservation techniques in Morocco through a literature review. It tracks a set of techniques adopted by farmers to remedy the lack of agricultural land, to enhance land conservation and improve its productivity. Many traditional soil and water conservation systems have been described and classified according to local water balance, topography, operation and objectives: impluvium runoff management, water infiltration increase, diversion of excess-runoff and runoff energy dissipation. Perhaps there exist still other installations not quoted here. Their effectiveness depends on multiple factors, which vary in time and space such as the climatic conditions (dryness) and socio-economic (emigration of youth). Key words: Water erosion, Soil and water conservation, Traditional water and soil management techniques, Land management, Water harvesting, MoroccoLa fragilité naturelle du milieu (relief accidenté, pluies agressives, substrats fragiles) associée à une fragilité humaine (pauvreté, précarité) conduisent à l’apparition et l’extension de phénomènes de dégradation des sols spectaculaires. L’érosion hydrique concerne affecte la productivité une grande partie des terres marocaines. Cette situation a incité les paysans à concevoir et à réaliser des aménagements pour réduire les pertes de terres, optimiser l’utilisation des eaux et valoriser les eaux pluviales. Des projets de Défense et Restauration des Sols (DRS) et de Conservation des Eaux et des Sols (CES) ont également été conduits par les institutions d’aménagement des terres dans ces zones pour les mêmes objectifs. Cette étude vise, à travers une recherche bibliographique, à inventorier les techniques de conservation des eaux et des sols au Maroc. Elle retrace un ensemble de techniques adoptées par les agriculteurs pour remédier au manque de terres agricoles, leur conservation et l’amélioration de leur productivité. De nombreux systèmes traditionnels de conservation de l’eau et des sols ont été décrits et classés en fonction du bilan hydrique local, de la topographie, de leur fonctionnement et de leurs objectifs : la capture du ruissellement sous impluvium, l’infiltration totale de l’eau, la diversion des excédents d’eau et la dissipation de l’énergie du ruissellement. Il existe peut-être encore d’autres aménagements non cités ici. Leur efficacité dépend de multiples facteurs qui varient dans le temps et dans l’espace comme les conditions climatiques (sécheresse) et socio-économiques (émigration des jeunes). Mots clés: Érosion hydrique, Conservation des eaux et sols, Techniques traditionnelles de gestion de l’eau et du sol, Aménagement et gestion des terres, Collecte des eaux pluviales, Maro

Evaluation Des Performances Du Modele Agro-Hydrologique SWAT à Reproduire Le Fonctionnement Hydrologique Du Bassin Versant Nakhla (Rif occidental, Maroc)

Une compréhension de toutes les composantes du bilan hydrique est indispensable pour raisonner les mesures de gestion rationnelle et durable de la ressource en eau. Malheureusement, plusieurs composantes du bilan hydrique ne sont pas facilement mesurables et le recours à la modélisation est souvent nécessaire. Pour ce faire, le modèle SWAT 2012 (Soil and Water Assessment Tool) a été mis en oeuvre à un pas de temps mensuel et journalier pour évaluer sa capacité à représenter le fonctionnement du bassin versant Nakhla, situé à 20 kilomètres au sud de la ville de Tétouan. Le traitement préalable des données existantes sur le bassin (MNT, pédologie, images satellitaires, données climatiques) a permis de reproduire les caractéristiques naturelles du terrain à une résolution spatiale adaptée aux objectifs de l’étude. La méthodologie adoptée repose sur l’usage du système d’information géographique libre (QGIS) combiné avec le modèle agro-hydrologique SWAT pour effectuer des opérations d’analyse et de modélisation du fonctionnement hydrologique à l’échelle du bassin versant et l’outil SWAT-Cup pour optimiser les opérations d’analyse de sensibilité et d’incertitude. Le processus de calibration est réalisé aux échelles temporelles mensuelle et journalière au niveau de la station Timezouk et au cours de trois périodes : de 1980 à 1983 pour l’initiation, de 1984 à 1987 pour la calibration et de 1988 à 1990 pour la validation. Les résultats obtenus après calage et validation à l’échelle mensuelle montrent une simulation satisfaisante des débits puisque la comparaison des débits mensuels observés et simulés pour la période de calibration a abouti à un NSE de 0,83 et un R2 de 0,88 au niveau de la station Timezouk. Les résultats à l’échelle journalière ne sont pas satisfaisant (NSE< 0.5), ce qui montre que la représentation de la dynamique haute-fréquence des flux d’eau doit encore être améliorée. A comprehension of all the components of water balance is essential for rational and durable management of the water resource. However, the direct assessment of several components of the water balance is very difficult and the use of modeling is often necessary. SWAT 2012 (Soil and Water Assessment Tool) model was thus implemented on a monthly and daily time steps to assess his ability to reproduce the hydrological functioning for the Nakhla watershed, which is located at 20 kilometers in the south of the city of Tetouan. Treatment of environmental data (MNT, pedology, satellite imagery and climatic data) allowed to describing the natural characteristic of the field at a resolution adapted to the objectives of the study. Adopted methodology consisted in the combined use of the SWAT agro hydrological model implemented in the QGIS geographical information system open source for operations of analysis and modeling of hydrological processes at the level of the watershed area and of SWAT-CUP tool to optimize the operations of sensitivity and uncertainty analysis. The calibration process was performed on two temporal scales; monthly and daily; and on the stations Timezouk; and over three periods: warm-up period from 1980 to 1983, calibration period from 1984 to 1987, and the validation period from 1988 to 1990. The results acquired after calibration and validation at monthly time step were satisfactory and presented good level of realism in the simulation of the discharge. The comparison of the monthly observed and simulated discharges for the period of calibration gave a NSE of 0.83 and R2 of 0.88 at the Timezouk station. Nevertheless, daily results are not satisfactory (NSE< 0.5), thus further improvements are required to better simulate the processes at a finer time step