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Accueil du site → Doctorat → Allemagne → Assessment of dynamic processes and evolutionary trends of the western part of the arid Chilean coastal range : relationship between river catchments and coastal dynamics of the Coquimbo Bay system, Chile

Eberhard Karls Universität Tübingen (2017)

Assessment of dynamic processes and evolutionary trends of the western part of the arid Chilean coastal range : relationship between river catchments and coastal dynamics of the Coquimbo Bay system, Chile

Soto Bäuerle, Maria Victoria

Titre : Assessment of dynamic processes and evolutionary trends of the western part of the arid Chilean coastal range : relationship between river catchments and coastal dynamics of the Coquimbo Bay system, Chile

Auteur : Soto Bäuerle, Maria Victoria

Université de soutenance : Eberhard Karls Universität Tübingen

Grade : Doktors der Naturwissenschaften (Dr. rer. nat.) 2017

Résumé partiel
Semiarid environments are climatically, ecologically, hydrologically and socio-economically complex systems, particularly when they are subject to climate change and anthropic interventions. The northern coast of Chile shows a very strong influence of the ENSO (El Niño South Oscillation) dynamics and El Niño events that triggered landslides, debris flows, flashfloods and river flooding. These natural processes are considered as hazards that negatively affect human settlements. In the study area, the growth of urban areas and the expansion of cultivated agricultural land for export purposes has generated and increased susceptibility to natural hazards and hence, increased the related risks. These systems show particular features and landforms inherited from different morpho-climatic domains. Hence, an assessment of the present day landscape must take into account the inherited landforms and features as well as present day landscape forming processes. The geomorphic processes in the catchments draining into Coquimbo Bay are activated and turn into dynamic conditions during extreme rainfall episodes associated with El Niño events. Hence, they trigger geomorphological and hydrological processes that activate the hydrographic network with a sporadic regime. Consequently, there is sediment transport through the watershed to the shoreline that is kept in balance by sandy beaches and accumulation in the sand dune fields despite semi-arid environmental conditions. We hypothesize that the morphodynamic stability of the coastal range and its associated catchments with high geodynamic potential is linked to the occurrence of extreme pluviometric events. In consequence, the basins are episodically reactivated generating extreme morphological dynamics affecting existing populated areas. These processes dominate the current sedimentary transfer mechanism from the basins to the waterfront and longshore. Consequently, this study contributes to the understanding of the geomorphological dynamics of the semiarid coastal area of Chile that is highly affected by extreme weather events. In turn these events trigger dynamics processes and natural hazard conditions. The methodology to achieve the aims and objectives of this study is based on detailed geomorphological analyses of the study area. This includes the generation of a geomorphological map according to the main influencing processes and related forms and features. Particularly, the landscape is characterized by the relationship between slope systems determined by their lithology and the potential mass contribution to the stream network. The geological information was extracted from geological maps. Fluvial terraces, alluvial fans and glacis were mapped based on stereo photointerpretation and validated by a field survey during 2012-2014.

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Page publiée le 14 janvier 2019