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Atmospheric pressure map at the level of 500 Hectopascal on 28 November 2014. The profound study of the satellite photos and the meteorological maps of November 28, 2014 clearly show a rare atmospheric situation as we notice the contraction and regression of the Azores Pressure (H in red color, left of picture) towards the South West besides getting separated from the Robin Pressure located over Eastern Europe and Russia. The latter was an obstacle and a blockade before Xandra Depression situated over the Atlantic Ocean, stopping it from moving towards the East, within the frame of a normal zoned air cycle, and making it move southward in the direction of Morocco in the form of cold humid air masses exemplified in a deep valley (Thalweg) which is considered as an extension of the Iceland Depression of which the atmospheric pressure reached its lowest levels as its value was 982
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p> In November 2014, the central and southern Morocco have experienced extreme rainfall reached 287 mm and exceeded 240 mm on the last ten days of that same month .In Agadir city the annual average precipitations is 236 mm. Through reading and analysis of a long chain of Agadir station climate data (100 years), it becomes clear that the exceptional...
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Citations
... With regard to economic activities, the agricultural and industrial sectors are most vulnerable to flood impacts. Floods have caused extensive and large-scale damage to crops and livestock [20,21]. For instance, the Gharb Valley, one of Morocco's largest agricultural production areas, is frequently impacted by riverine flooding from the adjacent Sebou River [22]. ...
This paper presents a comprehensive river discharge analysis to estimate past and future hydrological extremes across Morocco. Hydrological simulations with historical forcing and climate change scenario inputs have been performed to better understand the change in magnitude and frequency of extreme discharge events that cause flooding. Simulations are applied to all major rivers of Morocco, including a total of 16 basins that cover the majority of the country. An ensemble of temperature and precipitation input parameter sets was generated to analyze input uncertainty, an approach that can be extended to other regions of the world, including data-sparse regions. Parameter uncertainty was also included in the analyses. Historical simulations comprise the period 1979–2021, while future simulations (2015–2100) were performed under the Shared Socioeconomic Pathway (SSP) 2–4.5 and SSP5–8.5. Clear patterns of changing flood extremes are projected; these changes are significant when considered as a proportion of the land area of the country. Two types of basins have been identified, based on their different behavior in climate change scenarios. In the Northern/Mediterranean basins we observe a decrease in the frequency and intensity of events by 2050 under both SSPs, whereas for the remaining catchments higher and more frequent high-flow events in the form of flash floods are detected. Our analysis revealed that this is a consequence of the reduction in rainfall accumulation and intensity in both SSPs for the first type of basins, while the opposite applies to the other type. More generally, we propose a methodology that does not rely on observed time series of discharge, so especially for regions where those do not exist or are not available, and that can be applied to undertake future flood projections in the most data-scarce regions. This method allows future hydrological hazards to be estimated for essentially any region of the world.
Flood frequency analysis could be a tool to help decision-makers to size hydraulic structures. To this end, this article aims to compare two analysis methods to see how rare an extreme hydrometeorological event is, and what could be its return period. This event caused many deadly floods in southwestern Morocco. It was the result of unusual atmospheric conditions, characterized by a very low atmospheric pressure off the Moroccan coast and the passage of the jet stream further south. Assessment of frequency and return period of this extreme event is performed in a High Atlas watershed (the Ghdat Wadi) using historical floods. We took into account, on the one hand, flood peak flows and, on the other hand, flood water volumes. Statistically, both parameters are better adjusted respectively to Gamma and Log Normal distributions. However, the peak flow approach underestimates the return period of long-duration hydrographs that do not have a high peak flow, like the 2014 event. The latter is indeed better evaluated, as a rare event, by taking into account the flood water volumes. Therefore, this parameter should not be omitted in the calculation of flood probabilities for watershed management and the sizing of flood protection infrastructure.
The brown trout s.l. has been the focus of numerous phylogeographic and conservation studies due to its socioeconomic importance, its marked genetic and phenotypic differentiation and its broad distribution range. Especially interesting evolutionary patterns are observed for populations occupying peripheral areas of a distribution range, such as in the case of the highly isolated trout populations in Morocco.
Continuous stocking programs may conceal natural genetic patterns, making it challenging to discern evolutionary patterns. In Morocco, trout stocking programs have been implemented to increase the genetic diversity of native populations by pooling fish of different origins in the Ras el Ma hatchery (Azrou region) and then stocking them in the different basins. In this study, phylogenetic and phylogeographic patterns, as well as genetic structure and diversity, of Moroccan trout populations were analyzed to evaluate the impact of continuous fish stocking on evolutionary processes in order to better distinguish between natural and human-mediated patterns.
Two mitochondrial and nine microsatellite markers were analyzed for all populations along the entire distribution range of brown trout in Morocco. Phylogenetic and phylogeographic analyses rendered two highly divergent evolutionary lineages, one comprising populations in the Drâa Basin and a second grouping the remaining Moroccan populations. Divergence of the Drâa lineage occurred during the Upper Pliocene, whilst differentiation within the second lineage coincided with the onset of the Pleistocene.
Genetic structuring among populations was evident. Nevertheless, populations exhibiting higher levels of genetic diversity were those affected by human-mediated processes, making it difficult to associate this diversity with natural processes. In fact, highly geographically isolated, not stocked populations showed the lowest values of genetic diversity. Although stocking management may increase the genetic diversity of these populations, it could also lead to the loss of local adaptive genotypes. Hence, current trout conservation programs should be revised.
