Geological risk assessment of Amtoudi Agadir in southern Morocco: a key case for sustainable cultural heritage

Medieval fortified granaries known as “agadirs” are very common in southern Morocco, being catalogued as world cultural heritage by United Nations. These Berber buildings (made of stones and tree trunks) usually located on rocky promontories, constitute historical testimonials related to the origin of Morocco, and, as tourist attractions, have a positive impact on the local economy. The sustainability of these ancient monuments requires geological-risk evaluations of the massif stability under the agadir with the proposal of stabilization measures, and an architectonic analysis with appropriate maintenance of the structural elements. An interdisciplinary study including climate, seismicity, hydrology, geology, geomorphology, geotechnical surveys of the massif, and diagnosis of the degradation of structural elements have been performed on the Amtoudi Agadir, selected as a case study. The main findings from this study are that the prevalent rocks used for construction (coming from the underlying substratum) are good-quality arkosic sandstones; the SW cliffs under the agadir are unstable under water saturation; some masonry walls are too thin and lack interlocking stones and mortar; and failures in the beams (due to flexure, fracture, and exhaustion in the resistance due to insect attacks or plant roots) are common. The basic risk assessment of ancient buildings of cultural heritage and their geologic substratum are needed especially in undeveloped areas with limited capacity to implement durable conservation policies. Therefore, recommendations have been provided to ensure the stability and maintenance of this important archaeological site.This research was supported by Urbino University found (Resp. F. Guerrera); by CGL2011-30153-CO2-02 and CGL2012-32169 research project (Spanish Ministry of Education and Science); and by research groups and projects of the Generalitat Valenciana from Alicante University (CTMAIGA)

Fission track thermochronology of the Beni Bousera peridotite massif (Internal, Rif, Marocco) and the exhumation of ultramafic rocks in the Gibraltar Arc

International audienceThe Beni Bousera peridotite massif and its metamorphic surrounding rocks have been analyzed by the fission track (FT) method. The aim was to determine the cooling and uplift history of these mantle and associated crustal rocks after the last major metamorphic event that dates back to the Lower Miocene–Upper Oligocene time (∼22–24 Ma). The zircon FT analyses give an average cooling—i.e., below 320 °C—age of ∼19.5 Ma. In addition, the apatite FT data give an average cooling—i.e., below 110 °C—age of ∼15.5 Ma. Taking into account the thermal properties of the different thermochronological systems used in this work, we have estimated a rate of cooling close to 50 °C/Ma. This cooling rate constrains a denudation rate of about ∼2 mm year−1 from 20 to 15 Ma. These results are similar to those determined in the Ronda peridotite massif of the Betic Cordilleras documenting that some ultrabasic massifs of the internal zones of the two segments of the Gibraltar Arc have a similar evolution. However, Burdigalian sediments occur along the Betic segment (Alozaina area, western Betic segment) unconformably overlying peridotite. At this site, ultramafic rock was exposed to weathering at ages ranging from 20.43 to 15.97 Ma. Since the Beni Bousera peridotite was still at depth until 15.5 Ma, we infer that no simple age projection from massif to massif is possible along the Gibraltar Arc. Moreover, the confined fission track lengths data reveal that a light warming (∼100 °C) has reheated the massif during the Late Miocene before the Pliocene–Quaternary tectonic uplift

Organic-walled dinoflagellate cysts from the Upper Cretaceous-Lower Paleocene succession in the western External Rif, Morocco: new species and new biostratigraphic results

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A hydrological–economic model for sustainable groundwater use in sparse-data drylands: Application to the Amtoudi Oasis in southern Morocco, northern Sahara

A hydrological–economic model is introduced to describe the dynamics of groundwater-dependent economics (agriculture and tourism) for sustainable use in sparse-data drylands. The Amtoudi Oasis, a remote area in southern Morocco, in the northern Sahara attractive for tourism and with evidence of groundwater degradation, was chosen to show the model operation. Governing system variables were identified and put into action through System Dynamics (SD) modeling causal diagrams to program basic formulations into a model having two modules coupled by the nexus ‘pumping’: (1) the hydrological module represents the net groundwater balance (G) dynamics; and (2) the economic module reproduces the variation in the consumers of water, both the population and tourists. The model was operated under similar influx of tourists and different scenarios of water availability, such as the wet 2009–2010 and the average 2010–2011 hydrological years. The rise in international tourism is identified as the main driving force reducing emigration and introducing new social habits in the population, in particular concerning water consumption. Urban water allotment (PU) was doubled for less than a 100-inhabitant net increase in recent decades. The water allocation for agriculture (PI), the largest consumer of water, had remained constant for decades. Despite that the 2-year monitoring period is not long enough to draw long-term conclusions, groundwater imbalance was reflected by net aquifer recharge (R) less than PI + PU (G < 0) in the average year 2010–2011, with net lateral inflow from adjacent Cambrian formations being the largest recharge component. R is expected to be much less than PI + PU in recurrent dry spells. Some low-technology actions are tentatively proposed to mitigate groundwater degradation, such as: wastewater capture, treatment, and reuse for irrigation; storm-water harvesting for irrigation; and active maintenance of the irrigation system to improve its efficiency.This research was supported by the Research Project PRIN-2003 from University of Urbino, the Portuguese FCT Research Project PTDC/CLI/72585/2006, the Spanish CICYT Research Projects CGL2011-30153-CO2-02 and CGL2012-32169, and the Research Project VIGROB-053 from University of Alicante

Arcaheometric study of a typical medieval fortified granary (Amtoudi Agadir, Anti-atlas Chain, southerm Morocco): a key case for the maintenance and restoration of historical monuments

none9sìAn interdisciplinary archaeometric study concerning the Amtoudi Agadir, declared World Cultural Heritage (northern border of the Sahara Desert, southern Morocco), was performed consisting in lithostratigraphic reconstruction of the bedrock, diagnosis of constitutive materials (stones, mortars, and wooden elements), and analyses of constructive techniques and architectonic elements (load-bearing and supported structural elements). The medieval agadir (fortified granary) was built directly on a rocky piton with rocks of the substratum with traditional materials and ancestral techniques. The stones have been identified and classified into four petrofacies. Degradation such as biological attacks, chromatic alteration, erosion, exfoliation, and fissuration on the stones have been characterized. Recommendations for conservation and maintenance of the rocks have been proposed in compatibility with the environment. Load-bearing (masonry walls) and supported structural elements (ceiling structures) have also been studied in order to define their stability. Worst cases of 1- and 2-height walls, together with worst cases of the wooden or stone ceiling structures have been analyzed. Materials, techniques, and dimensions have been characterized for possible failures to shearing, bending, and flexural buckling as guide for maintenance of the agadir. The main problems of the walls derive from excessively thin construction with a lack of interlocking of the rocks and a diminished proportion or quality of mortar joining the rocks due to washing. It has been recommended to avoid thicknesses lower than 0.4 m for 2-height walls and lower than 0.3 m for 1-height walls. A nominal load has been estimated in the worst case (with wooden elements) for the ceiling structures of about 7.0 KN/m2. The calculations have indicated that a 25% increase over the nominal load would imply a risk of failure, the use of stone elements being preferable over wooden ones. With these propositions for the Amtoudi Agadir, new management and prospects for cultural tourism are feasible.openRaffaelli, G.; Robles-Marín, P.; Guerrera, F.; Martín-Martín, M.; Alcalá, F.J.; Amadori, M.L.; Asebryi, L.; Hassan, I. El Amrani El; León, J. Tejera De LéonRaffaelli, G.; Robles Marín, P.; Guerrera, Francesco; Martín Martín, M.; Alcalá, F. J.; Amadori, MARIA LETIZIA; Asebryi, L.; Hassan, I. El Amrani El; León, J. Tejera De Léo