Universität zu Köln

Walk, Janek ORCID: 0000-0002-3283-7214, Stauch, Georg, Reyers, Mark, Vasquez, Paulina, Sepulveda, Fernando A., Bartz, Melanie ORCID: 0000-0002-4703-6057, Hoffmeister, Dirk ORCID: 0000-0002-8178-557X, Brueckner, Helmut and Lehmkuhl, Frank (2020). Gradients in climate, geology, and topography affecting coastal alluvial fan morphodynamics in hyperarid regions - The Atacama perspective. Glob. Planet. Change, 185. AMSTERDAM: ELSEVIER. ISSN 1872-6364

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Abstract

Along the coast of the hyperarid Atacama Desert, late Quaternary alluvial fans emerge from the Coastal Cordillera to the Pacific Ocean between 20.5 degrees S and 25.5 degrees S. Coastal alluvial fans (CAF) show, in comparison to the interior fans of the Atacama Desert, pronounced recent activity. However, the complex interplay between climate, lithology, and tectonics affecting the CAF morphodynamics in such hyperarid coastal settings needs to be better understood. We therefore aim at assessing the major factors driving CAF activity and evaluate their effects along gradients. We conducted an extensive study relating climatic, lithologic, and tectonic characteristics to fan and catchment geomorphology of 123 CAF. Geomorphometric analyses are based on the 12.5 m TanDEM-X WorldDEM (TM), catchment lithology and faults are extracted from 13 regional geological maps, and the frequency of heavy rainfall events capable of activating CAF is derived from a Weather Research and Forecasting (WRF) regional climate model. Our results point to a primary climatic control on CAF morphodynamics shown in functional relationships with catchment hydromorphometric characteristics reflecting a high susceptibility to debris flows - the main CAF-constructing process. Catchment properties along the latitudinal gradient reflect the source of significant precipitation events: frontal systems and cut-off lows which mainly originate in the extratropics and become increasingly rare towards the north. The frequency of precipitation extremes can only be correlated to the hydromorphometry and geomorphic maturity of catchments that feature a high degree of sediment transport potential and generally do not cut back far into the Coastal Cordillera. Related to the strongly reduced influence of the Pacific precipitation source towards the east, this additional climatic transition is governed by the orographic effect of the steep W-E gradient in topography. In contrast, source-area lithology is of negligible relevance for CAF catchment morphometry and fan activity. An important indirect influence of tectonics, however, can be seen in the long-term (neo)tectonic activity within the Coastal Cordillera, which in turn shapes catchments and controls the topography.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Walk, Janek UNSPECIFIED orcid.org/0000-0002-3283-7214 UNSPECIFIED Stauch, Georg UNSPECIFIED UNSPECIFIED UNSPECIFIED Reyers, Mark UNSPECIFIED UNSPECIFIED UNSPECIFIED Vasquez, Paulina UNSPECIFIED UNSPECIFIED UNSPECIFIED Sepulveda, Fernando A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bartz, Melanie UNSPECIFIED orcid.org/0000-0002-4703-6057 UNSPECIFIED Hoffmeister, Dirk UNSPECIFIED orcid.org/0000-0002-8178-557X UNSPECIFIED Brueckner, Helmut UNSPECIFIED UNSPECIFIED UNSPECIFIED Lehmkuhl, Frank UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-351677
DOI:	10.1016/j.gloplacha.2019.102994
Journal or Publication Title:	Glob. Planet. Change
Volume:	185
Date:	2020
Publisher:	ELSEVIER
Place of Publication:	AMSTERDAM
ISSN:	1872-6364
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language NORTHERN CHILE; DEBRIS-FLOW; EL-NINO; SEDIMENT CONNECTIVITY; SOUTH-AMERICA; MAGMATIC ARC; FORE-ARC; TARAPACA REGION; MARINE TERRACES; MIOCENE AGE Multiple languages Geography, Physical; Geosciences, Multidisciplinary Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/35167