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EN
On the one hand, this study assesses the evolution of climatological parameters in the Zaër region between 1986 and 2021 and, on the other hand, it studies the effect of climatic variations on cereal and leguminous crop yields between 2000 and 2020, in order to further elucidate the consequences of their fluctuations on crop yields and to mitigate their regression process by making it possible to analyze favorable adaptation strategies for agricultural systems that can be envisaged for the coming decades. The methodology is based on the use of trend curves and statistics (averages and standard deviations) to analyze changes in climatic parameters and their effects on yields. The results show that the average temperature in the Zaër region is set to rise from 19°C in 1986 to 22°C in 2020. Higher temperatures mean lower yields of rainfed cereals and pulses, and average rainfall varies between 330 mm in 1986 and 570 mm in 2021, with rainfall increasing the likelihood of crop failure in the short term and reducing production in the long term. In addition, the rainy season is short (4 to 5 months per year). These characteristics make Zaër’s agriculture very sensitive to climate-related threats. Studying seasonal climate forecasts before each rainy season can help farmers to minimize rainfall hazards and thus optimize their crop yields.
EN
The Assaka watershed is one of the largest watersheds in the Guelmim region in southern Morocco. It is frequently exposed to the many flooding events that can be responsible for many costly human and material damages. This work illustrates a decision-making methodology based on Analytical Hierarchy Process (AHP) and Fuzzy Logic Modelling (FLM), in the order to perform a useful flood susceptibility mapping in the study area. Seven decisive factors were introduced, namely, flow accumulation, distance to the hydrographic network, elevation, slope, LULC, lithology, and rainfall. The susceptibility maps were obtained after normalization and weighting using the AHP, while after Fuzzification as well as the application of fuzzy operators (OR, SUM, PRODUCT, AND, GAMMA 0.9) for the fuzzy logic methods. Thereafter, the flood susceptibility zones were distributed into five flood intensity classes with very high, high, medium, low, and, very low susceptibility. Then validated by field observations, an inventory of flood-prone sites identified by the Draa Oued Noun Hydraulic Watershed Agency (DONHBA) with 71 carefully selected flood-prone sites and GeoEye-1 satellite images. The assessment of the mapping results using the ROC curve shows that the best results are derived from applying the fuzzy SUM (AUC = 0.901) and fuzzy OR (AUC = 0.896) operators. On the other hand, the AHP method (AUC = 0.893) shows considerable mapping results. Then, a comparison of the two methods of SUM fuzzy logic and AHP allowed considering the two techniques as complementary to each other. They can accurately model the flood susceptibility of the Assaka watershed. Specifically, this area is characterized by a high to very high risk of flooding, which was estimated at 67% and 30% of the total study area coverage using the fuzzy logic (SUM operator) and the AHP methods, respectively. Highly susceptible flood areas require immediate action in terms of planning, development, and land use management to avoid any dramatic disaster.
EN
The significance of the issue lies in the pivotal role played by Wadi Ouergha, as a major tributary of Wadi Sebou. This watercourse directly contributes to the El Wahda dam, the largest in the Kingdom of Morocco and the second largest in Africa. With its substantial storage capacity and noteworthy annual sedimentation volume, this dam’s storage capacity is notably impacted. The ongoing decline in the capacity of the El Wahda dam could potentially accelerate due to shifts in surface water mobilization rates and the worsening degradation of marl soils within the catchment, coupled with alterations in vegetation cover. The aim of this study is to examine the changes in the erosion rate within the Wadi Ouergha watershed over a span of 40 years, covering the periods 1980–2000 and 2001–2020. This comparative analysis aims to ascertain whether erosion control measures have effectively reduced the erosion rate in the region over time. To assess soil losses occurring in the Wadi Ouergha watershed, impacting the El Wahda dam, we employed the RUSLE model to determine the rate and vulnerability of the catchment to water erosion. The results indicate that erosion control measures have been effective in combating soil erosion in the potential region with high erosion risk, with a 13.83% reduction in the average erosion rate between the two periods, from 25.3 to 21.8 (tons/hectare/year). This study presents a groundbreaking contribution by unveiling, for the first time, the dynamic evolution of water erosion patterns over time. It offers a comprehensive assessment of the effectiveness of erosion control measures implemented within the most vulnerable zones.
EN
This qualitative study of the soils of the Zaër region is part of a context of good development, preservation and sustainability of agricultural soils. Its aim is to establish a reference framework for the physico-chemical characteristics of the region’s agricultural soils. It was based on a spring sampling campaign carried out in 2021. Composite samples taken from thirteen sites with diverse soils were analysed in the laboratory. The soil analysis results were compared with reference values. The soils examined were moderately acidic to moderately alkaline, with low levels of organic matter. Nevertheless, concentrations of exchangeable calcium and magnesium were found to be sufficient, while sodium levels were very low. Furthermore, cation exchange capacity was low in spring, reflecting the soil’s high and low nutrient retention capacity respectively. Phosphorus and potassium levels appear to be low. In the light of these results, the use of organic and mineral fertilisers and calcium amendments is strongly recommended to improve agricultural quality and productivity in the region studied.
EN
The Water erosion of soils considered the main cause of soil degradation in Morocco. Soil erosion not only reduces agricultural productivity but also reduces water availability, and negatively contributes to the quality of drinking water sources. Consequently, the assessment of soil erosion risk has become the objective of several researches at the Moroccan level. It is in this context the purpose of this study is to assess the soil erosion risk using a Revised Universal Soil Loss Equation (RUSLE) / Geographic Information System (GIS) approach at the scale of the watershed of the Oued Ykem (western Morocco). (GIS) techniques were adopted to process the data obtained at the watershed scale, of reasonable spatial resolution (30 m) for the application of the RUSLE model. The latter is a multiplication of the five factors of erosion: the rainfall erosivity (R), the soil erodibility (K), the slope length and steepness (LS), the cover and management and the support practice (P). Each of these factors has been expressed as a thematic map. The Oued Ykem watershed is an elongated coastal basin with an area of 516 km2. It is part of the Atlantic coastal basins of western Morocco. It is located southwest of the city of Rabat. Oued Ykem is characterized by a semi-arid climate with oceanic influence. Rare and irregular rains, mostly stormy in nature, combined with deforestation, cause erosion and irregular flow. Its flow-rate increases during the winter. Extreme flows-rate can be recorded after exceptional and very intense showers upstream of the basin. The resulting soil loss map, with an average erosion rate varying from 0 to 54 t/ha/year, showed low erosion. Areas with a strong erosion rate exceeding 30 t/ ha/ year cover about 3.8 % of the basin area. The analysis of the erosion risk map, in comparison with the maps of the different factors in the equation, showed a clear and important influence of the vegetation cover on the soil erosion (C factor is from 0.03 to 0.9), followed by the topographic factor, especially the slope (LS factor varies from 0 to 56.71).
EN
The town of Lixus is the most important archaeological site on the Moroccan Atlantic coast. It is essentially built, from at least 12 centuries BC, by rocks of sedimentary origin. A preliminary diagnosis allowed us to identify the main factors of the physico-chemical degradation observed on the buildings of the monument. The interest of the conservation of this archaeological richness requires an intervention of safeguard, which will go beyond the operation of protection of its perimeter to another desired action of development of its tourist and cultural purposes. The objective of this work mainly concerns a comparative study of the petro-physical characteristics of the sandstones sampled at various levels of the geological formation located to the northwest of the Lixus site, as a substitute stone, which will be used for any eventual rehabilitation operation. On the basis of the definition of the main causes of pathologies observed at the level of the site, the realization of these categories of action are first carried out by an experimental simulation of accelerated aging by "imbibition-drying" cycling. Then the call for petrographic analyzes where the thin sections revealed the mineralogical composition, the proportion of the figured elements and the nature of the bonding phase of the rocks tested; then the chemical characterization carried out by XRF fluorescence (X-Ray Fluorescence) and the quantification of the carbonated fraction by calcimetry. Also and with the help of geotechnical tests, in particular the determination of the porosity, the density and the hydric density as well as the uniaxial compressive strength (RC) and the rebound index (hardness by sclerometer). The confrontation of all the results obtained reveal a valid estimate of the potential for durability and compatibility in the sense of homogeneity with the material to be replaced, in view of their significant mineralogical composition in terms of sufficient quantity of silica and calcite. The tests used allowed the refinement of the discriminating mechanical parameters, they highlighted the relationships between the mechanical resistance and the physical properties of this replacement stone, particularly the high mechanical resistance (50.1–74.9 MPa), the absolute density values (2.54–2.68) and the rebound index (30–34) significant, which evolve inversely proportional to the low porosity values (1.7–2.20). However, all these recorded results have qualified this rock as a resistant lithology according to the classification adopted by the International Society of Rock Mechanics (ISRM), recommended for any possible renovation of Lixus.
EN
Geochemical study of twenty-seven marine sediments of the Levrier Bay used eleven heavy metals to display descriptive statistics and to assess the environmental impact of this industrial area. The analysis of eleven heavy metals (Pb, Zn, Cu, Ni, V, Cr, Co, Hg, Cd, As and Mo), major and other trace elements, were performed by ICP-MS. Pollution load Index (PLI) show low degree of contamination. Geochemical Index (Igeo) and enrichment Factor (EF) have been used to assess the environment quality at varied sites in sediments. Results display moderate concentrations for the most of elements excepted the As and Hg which often are upon the amount measured in the UCC baseline. The local presence Hg and As, limited to some sites of the area, allow to conclude that the sediments of the Lévrier Bay didn’t suffer from the human activities in the area.
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