Investigating possible links between the North Atlantic Oscillation and rainfall variability in Marrakech (Morocco)

Eighty-two-year rainfall time series have been studied together with climatic patterns of NAO using classical statistical methods. Then, the wavelet approach has been applied to show annual (1 year (1y)) and inter-annual (2–4 years (2-4y), 5–8 years (5-8y), and 8–16 years (8-16y)) modes distributed following four major discontinuities: 1945, 1960, 1975, and 1995. The 1y, 2-4y, and 5-8y powers show high energy during the wet period 1922–1930 and a low one in 1928–1938. After 1945, the annual mode highlights a high energy while the inter-annual modes present low energy. Between 1975 and 1995, powerful modes of 1 and 2–4 years are identified with low power of 5-8y and 8-16y modes. Since 1995, the low power of 5–8y decreases, while the 8-16y mode emphasizes a high variability. The coherence between NAO and Marrakech precipitation is strongly defined for low frequencies with a total contribution of 75 %. This coherence is in phase in the beginning and presents out phase signs since 1945. The change of phase can be associated to a decreasing of coherence especially around 1990. This finding is useful to understand the relationship between the hydrological variability and NAO climate patterns in the southern side of the Mediterranean Sea.     

Diagnostic of physicochemical and bacteriological quality of fez wastewaters rejected in Sebou River: Morocco

The high demographic growth of the city of Fez, as well as the implantation of social districts in the periphery of the city, is leading to the deterioration of water quality of the Sebou River. This critical situation has considerable effects on the environment of Fez, where this river has become in its vicinity a sewer leading to various nuisances. The total pollution added by the city rises to 100,000 m³/day, it will reach 120,000 m³/day by 2015. Sebou River represents the main superficial network of Fez region. It is threatened currently by human activities such as urban, industrial and agricultural wastes. To evaluate water quality of this river, a study was carried out to determine the physicochemical and bacteriological parameters during the two seasons: winter (November 2006) and summer (July 2007). Results show a high level of pollution from various sources notably by Fez industrial wastewaters. Downstream discharges of the city and downstream the point of confluence of Fez stream and Sebou River, we note a low content in dissolved oxygen; high contents in suspended matter, nitrites and DBO₅ and high conductivity, high concentrations in phosphates, sulphates and heavy metals (Cd, Hg, Cr, Cu and Zn). This study also presents an evaluation of the bacterial load in discharged wastewaters. The concentrations of fecal coliform and fecal streptococci bacteria exceed greatly the norms recommended by WHO.     

An Integrated Approach for Rapid Delineation of K-Rich Syenites Suitable as Unconventional Potash Resources

Natural Resources Research - Potassium (K)-rich igneous rocks include a variety of silica-undersaturated and alkaline rocks, which distinguished by their elevated K2O contents. These rocks have...     

Spatial and temporal analysis of the drought vulnerability and risks over eight decades in a semi-arid region (Tensift basin: Morocco)

Theoretical and Applied Climatology - The multiple downscaled scenario products allow us to assess the uncertainty of the variations of precipitation and temperature in the current and future...     

Combined hydrogeological and nitrate modelling to manage water resources of the Middle Soummam Aquifer,Northeast of Algeria

Water management is one of the most challenges in Algeria, a semi-arid Mediterranean country confronted to a serious water stress. The country will have to endure, beyond 2025, a situation of chronic water penury, adding an excessive pollution of the majority of groundwater reservoirs. The management of water resources by combined approach using hydrogeological model and nitrates evolution model was experimented in the Middle Soummam valley. The alluvial aquifer, offering good hydrodynamic and geometrical characteristics, is over-exploited, providing in drinking water Akbou and Tazmalt cities and irrigation perimeters. If exploitation continues at these steady paces, the depletion of the water resource and the hydrochemical imbalance will be inevitable. On the one hand, the results of hydrodynamic model, based on an increase of the water takings and simulated needs from 24.71 Mm³/year in 2015 into 39.69 Mm³/year in 2030, show a critical withdrawal. The aquifer budget expresses the inversion of flow between the wadi and the aquifer where the wadi feeds the groundwater reservoir. This hydrodynamic inversion was attributed to simulated pumping rates which increased and exceeded 100,000 m³/day, but the aquifer was partially relieved by the weight of the exploitation through Tichy Haf dam. The water management strategy adopted in this study was based on management measures promoting zones, which have been delimited between Tazmalt and Akbou, and containing important water quantities available in the axis of the valley. However, according to the depleted in isotopes of ¹⁸O and ²H, which could be explained by the influence of a paleoclimatic effect and suggested that the aquifer recharge would have largely been made under a colder climate, pumped groundwater could be old, and the implementation of new pumping sites has been studied minutely. On the other hand, the hydrogeochemical modelling allowed following nitrates concentrations in order to project their evolution. Four wells on 25 react in face to the imposed conditions in each scenario simulated until 2030, showing inertia of pollution, and confirmed after three series of tests. This inertia would be related to the hydraulic gradients and hydraulic conductivities, aquifer thickness and recharge. The low hydraulic gradients lead to a rather slow flow velocity and thus to an inertia in the dispersion of nitrates, with a mass transport weakened by the hydrodynamic conditions. It is also related to the aquifer thickness; when the aquifer is powerful (65–85 m), the stock of water would be important and allows a dilution process. The reverse is true for the simulated boreholes where the concentrations remain invariant; the aquifer is less powerful (32–37 m). Finally, the recharge effect through the rain was evoked; the aquifer is unconfined, and the rain water and pollution that reached the piezometric level can remain in position in slow hydrodynamic conditions. The methodology was demonstrated through a combination of monitoring and modelling for both water quantity and quality and the importance to use numerical models to support water resources management strategy in the Mediterranean aquifers.