Drainage network dynamics and knickpoint evolution in the Ebro and Duero basins: From endorheism to exorheism

Struth, Lucía; García‐Castellanos, Daniel; Viaplana‐Muzas, Marc; Vergés, Jaume

doi:10.1016/j.geomorph.2018.11.033

Cited by 55 publications

(53 citation statements)

References 72 publications

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“…Such escarpments occur over a wide range of scales, from great escarpments (10 2 -10 3 km) that form in association with rifted passive margins, to erosional escarpments (10 0 -10 2 km). The latter form where deeply incised basins are juxtaposed against low-relief, high-elevation terrain (Strahler, 1952) due to, for example, lateral lithologic differences (Gallen, 2018) or differences in base level (Struth et al, 2019). Extreme slope asymmetry across a divide can also stem from river capture that redirects the drainage area to a lower base level (Bishop, 1995).…”

Section: Introductionmentioning

confidence: 99%

Drainage reversal toward cliffs induced by lateral lithologic differences

Harel

Goren

Shelef

et al. 2019

Geology

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Drainage reversals, an end-member case of drainage reorganization, often occur toward cliffs. Reversals are commonly identified by the presence of barbed tributaries, with a junction angle >90°, that preserve the antecedent drainage geometry. The processes that form reversed drainages are largely unknown. Particularly, barbed tributaries cannot form through a spatially uniform migration of the cliff and drainage divide, which would be expected to erase the antecedent drainage pattern, and tectonic tilting toward the cliff that could reverse the flow direction is inconsistent with geodynamic models of large-scale escarpment, where many reversals are documented. Here, we propose a new mechanism for drainage reversal, where the slope imbalance across a cliff, together with the high erodibility of sediments that fill cliff-truncated valleys, result in faster divide migration along valleys compared to interfluves. We demonstrate this mechanism along channels that drain toward the escarpment of the Arava Valley in Israel. Reversal is established by observations of barbed tributaries and opposite-grading terraces. We show that drainage reversal occurs when erodible valley fill exists, and that the reversal extent correlates with the thickness of this fill, in agreement with the predictions of the proposed mechanism. This new reversal mechanism demonstrates that valley fill could play an acute role in fluvial reorganization processes, and that reversals could occur independently of tectonic tilting.

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Section: Introductionmentioning

confidence: 99%

Drainage reversal toward cliffs induced by lateral lithologic differences

Harel

Goren

Shelef

et al. 2019

Geology

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“…Additionally, the progression of fluvial incision involves a gradual increase in lengthening of the valley slopes that may increase sediment supply even when discharge conditions are maintained, favouring the formation of downstream‐diverging profiles (Macar, ). In the particular case of the Duero basin, the progression of fluvial incision in the crystalline bedrock of the knickzone would have slowed down and regulated the migration of the erosive signal upstream (Struth et al, ). The absence of the highest sequence of terraces in reach 1 and the narrow surface extent occupied by the intermediate and low terraces contrasts with the wider terrace outcrops preserved in reach 2, where the sequence is more complete.…”

Section: Discussionmentioning

confidence: 99%

A GIS method to identify flat surfaces and restore relict fluvial long‐profiles from terrace remnants gives new clues on how large basins respond to endorheic–exorheic transitions (Duero basin, Iberian Peninsula)

Rodríguez‐Rodríguez

Antón

Pallàs

et al. 2020

Earth Surf Processes Landf

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Fluvial terraces are used as geomorphic indicators for deciphering long‐term landscape evolution. Knowing the distribution of fluvial terraces is essential for establishing former river profiles and their tectonic significance, for studying climate‐modulated processes of terrace development, or for defining fluvial network adjustments in response to sudden base‐level changes like those produced by fluvial captures. Multiple methods for automatic map production have been proposed based on the comparison of morphometric indices with those of the modern river course. Here we propose an alternative method to identify flat surfaces and scarps separating them from digital elevation models without setting comparisons with a modern river course and thus fully applicable to study flat landforms whatever their origin. Its application to the low‐relief landscape of the Cenozoic Duero basin has allowed the improvement of previous geomorphological maps and the analysis of fluvial network adjustments in response to a sudden base‐level fall after the opening of the Neogene endorheic basin towards the Atlantic Ocean. Reconstructed terrace long‐profiles suggest an initial episode of fast vertical incision followed by a period of repeated planation–aggradation–incision with the formation of 14 to 13 unpaired terrace levels. Changes observed in the pattern of terrace profiles are discussed with regard to changes in regional tectonics and base‐level variations. © 2019 John Wiley & Sons, Ltd.

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“…A drainage network is a dynamic system that adjusts to perturbations in the landscape, such as tectonic deformations and climate changes, to reach an equilibrium state between fluvial erosion and base level variations (Struth et al, 2019). Knickpoints represent a transient response to external perturbations.…”

Section: Knickpoint and Base-level Declinementioning

confidence: 99%

“…River capture is an inevitable phenomenon in the process of transient geomorphology adjustment, which will lead to changes in the spatial pattern of a drainage system in the basin. Depending on Chi-maps, the degree of disequilibrium of the drainage divides and the trend of horizontal motion needed to reach an equilibrium state can be visually reflected (Struth et al, 2019). We calculated the Chi-value distribution in the basin by taking the river outlet as x b so that the height differences between the two sides of the sub-basin and the river outlet are the same.…”

Section: Drainage Reorganizationmentioning

confidence: 99%

GIS and DEM based analysis of incision and drainage reorganization of the Buyuan River basin in the upper Lancang-Mekong of China since the Late Pleistocene

Fan

Yang

2020

J. Geogr. Sci.

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River incision and drainage reorganization have an important impact on the site selection of many major projects including city, road and others, and are the key issues of Quaternary environmental changes. Studies of river incision and river-network adjustment have traditionally been based on extensive field evidence, such as sediment age and beheaded river system. The Buyuan River basin is a large sub-basin of the upper Lancang-Mekong, with high mountains and extremely active erosion. The latter affects the preservation of the Quaternary period sediments leading to difficulties in understanding the main evolution characteristics of the basin. This study investigates differences in the equilibrium state of the longitudinal profile, infers incision rates, and evaluates drainage divide migration timelines using the stream-power incision model, the latest morphological dating, and Chi-plots (χ-z) based on digital elevation models (DEMs) on the GIS software platform. The final results show that two significant erosion base-level decreases occurred in the Late Pleistocene at least. The incision rate of the mainstream might have been 0-2.99 mm/yr since 100 ka BP and 0-3.28 mm/yr since 46 ka BP. The Chi-values across the divides suggest that space limited (or constrained) river reorganization and that there is no severe reorganization in the basin; the imbalance of traceable erosion only exists in local areas. The main driving force for the geomorphologic evolution of the Buyuan River basin is likely climate fluctuations rather than strong tectonic uplift since the Late Pleistocene.

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Drainage network dynamics and knickpoint evolution in the Ebro and Duero basins: From endorheism to exorheism

Cited by 55 publications

References 72 publications

Drainage reversal toward cliffs induced by lateral lithologic differences

Drainage reversal toward cliffs induced by lateral lithologic differences

A GIS method to identify flat surfaces and restore relict fluvial long‐profiles from terrace remnants gives new clues on how large basins respond to endorheic–exorheic transitions (Duero basin, Iberian Peninsula)

GIS and DEM based analysis of incision and drainage reorganization of the Buyuan River basin in the upper Lancang-Mekong of China since the Late Pleistocene

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