Holocene landscape evolution in the Baza Basin (SE-Spain) as indicated by fluvial dynamics of the Galera River

D Wolf,F.J García-Tortosa,C Richter,J Dabkowski,C.B Roettig,D Faust

doi:10.1016/j.qsa.2021.100030

D Wolf, F.J García-Tortosa + Show 4 more

Open Access

https://doi.org/10.1016/j.qsa.2021.100030

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Abstract

The concrete relationships between fluvial system behavior and potential influencing factors that are, among others, climate forcing, tectonics, and human activity are a key issue in geomorphological research. In this regard, especially the Iberian Peninsula is an area of great interest because its landscapes are highly sensitive towards climate changes and anthropogenic impact. Nowadays, the Iberian Peninsula reveals a strongly heterogeneous and spatially fragmented climate configuration. This should give rise to disparate behavior of fluvial geomorphic systems considering that climate is generally assumed the most important trigger of fluvial dynamics. In fact, river systems located in more humid and more arid regions in Iberia often reveal deviating patterns of Holocene floodplain evolution. This raises the question of whether these patterns were actually caused by a different climate history or if, alternatively, other factors might have been responsible. In this study, we investigated the Holocene floodplain evolution of the Galera River that is located in the upland of Eastern Andalucía (SE-Spain) named Baza Basin. A combination of detailed stratigraphic profile logging and close-meshed radiocarbon dating revealed that Holocene river dynamics generally followed the regional climatic development, which proves the Galera floodplain record to be a valuable archive of Holocene landscape evolution. However, we demonstrate that fluvial dynamics of the Galera system are hardly comparable to other river systems in Iberia even if the climate evolution was not so different. Our results suggest that in river systems with different basic conditions and catchment-specific configurations, similar climatic influences may lead to deviating fluvial process regimes (divergence phenomenon) because of substantial imprints of other parameters such as geological substratum, relief composition, tectonics, or human interventions.

Highlights

Today as in the past, the Iberian Peninsula reveals highly heteroge neous climate and environmental conditions demonstrating strong spatial variations (Vicente-Serrano et al, 2006; Queralt et al, 2009; Hidalgo-Munoz et al, 2011; Perez-Obiol et al, 2011; Lillios et al, 2016; Tarroso et al, 2016; Morellon et al, 2018)
This incision was linked to a deepening of more than 10 m according to the vertical distance between fluvial terrace remains of presumably late Pleistocene river gravels (SU1) and lowest Holocene deposits at the valley bottom
In Iberian river systems, late Pleistocene incision often related to sea-level lowering (Schulte et al, 2008; Vis et al, 2008; Wolf et al, 2014) that is unlikely to apply to the Galera River very far from the Atlantic as ultimate base level

Summary

Introduction

Today as in the past, the Iberian Peninsula reveals highly heteroge neous climate and environmental conditions demonstrating strong spatial variations (Vicente-Serrano et al, 2006; Queralt et al, 2009; Hidalgo-Munoz et al, 2011; Perez-Obiol et al, 2011; Lillios et al, 2016; Tarroso et al, 2016; Morellon et al, 2018) This means that climate relevant data in high spatial resolution is needed for reconstructing and understanding underlying mechanisms of the climate system and resulting earth surface dynamics. The millennia lasting impact of both droughts and degradation due to human land use resulted in progressive deforestation and large-scale erosion dynamics (Bellin et al, 2011; García-Alix et al, 2013) that even led to the for mation of badlands in different areas (Torri et al, 2000; Nadal-Romero and García-Ruiz, 2018) In these strongly dissected landscapes, environmental archives are largely absent and mostly limited to adja cent mountain regions From this follows that there is a high demand for studies of climate-sensitive terrestrial archives in order to understand past climate dynamics and predict future system changes due to global warming, especially in these dry regions in SE-Iberia

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