Avulsion at a drift-dominated mesotidal estuary: The Chubut River outlet, Patagonia, Argentina

Isla, Federico Ignacio; Espinosa, Marcela A.; Armesto, Belén Rubio; Escandell, Alejandra; Gerpe, Marcela Silvia; Miglioranza, Karina Silvia Beatriz; Rey, D.; Vilas, F.

doi:10.1016/j.jhydrol.2014.12.019

Cited by 14 publications

(4 citation statements)

References 23 publications

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“…The historical and hydro‐geomorphological approach (Spaliviero, ) appears as a simple but efficient framework for a better long‐term territorial planning (e.g., Forte, Pennetta, & Strobl, ; Nirupama & Simonovic, ; Spaliviero, De Dapper, & Maló, ). In this context, fluvial geomorphology provides a framework for flood‐risk assessment, especially through (a) delineation of flood prone areas in broad alluvial valleys by mapping flood‐related landforms and deposits, soil and plant associations, and flood observations (Benito & Hudson, ; Bodoque et al, ) and (b) paleohydrology reconstructions of the evolution of rivers (Isla et al, ) and lakes (Guerra, Piovano, Córdoba, Sylvestre, & Damatto, ).…”

Section: Introductionmentioning

confidence: 99%

A paleo‐hydro‐geomorphological perspective on urban flood risk assessment

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Brox‐Escudero

González

et al. 2019

Hydrological Processes

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Comprehensive flood risk assessment requires enhanced understanding of the coevolution of the river and its floodplain occupation. Paleoflood analysis to determine flood prone areas in combination with numerical simulations to estimate flood hazard and a historical analysis of urban development to consider the evolution of exposure to floods is a possible way forward. The well-documented 2006 extreme flood in the Biobío River system and the impacted metropolitan area of Concepción, Chile (~1 million inhabitants) was used as a complex scenario to test the reliability of the proposed method. Results showed that flood prone areas determined with hydro-geomorphological methods are consistent with those computed with numerical models based on detailed digital elevation models. The flood generation via superficial flow pathways resulting in inundated areas could explain that rivers tend to reactivate paleochannels in extreme conditions. Urban development progressively increased the city's exposure to floods from 0 ha in 1,751 to 1,363 ha in 2006 evidencing a lack of appropriate flood risk management. The 100-year peak discharge resulted in a high flood risk for about 5% of the total urbanized area of Concepción, and higher discharges are likely to reactivate a paleochannel that crosses the current city centre. We conclude that the proposed paleo hydro-geomorphology, hydraulic, and urban planning multimethod approach is a necessary tool to enhance understanding of flood risk in complex scenarios to improve flood risk management. K E Y W O R D SBiobío River, flood risk management, hydro-geomorphological approach, numerical modelling, paleoflood

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Section: Introductionmentioning

confidence: 99%

A paleo‐hydro‐geomorphological perspective on urban flood risk assessment

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Brox‐Escudero

González

et al. 2019

Hydrological Processes

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“…The DZIII (87 cm at the top) integrated three lithological units U7˗U9 and the late Holocene, covered the last 1,279±31 14 Patagonian estuarine regressive sequences used to be crowned by marsh or peaty levels rich in organic matter (Isla et al 2015). This is also the case for the organic-rich layer of the LCH sequence (U7).…”

Section: Diatomological Analysismentioning

confidence: 99%

Holocene coastal evolution of Colorado River Delta based on diatom assemblages, Northern Patagonia, Argentina

Fayó

Espinosa

Isla

2022

An. Acad. Bras. Ciênc.

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Diatom assemblages and coastal sedimentary facies succession in the deltaic plain of the Colorado River (Argentina) were studied in order to reconstruct the environment conditions in response to Holocene eustatic sea-level changes and delta progradation. Samples were selected from a 200˗cm core (39°35'52" S, 62°6'43" W). Chronology was based on radiocarbon datings in bulk samples and mollusk shells.Nine lithological units were recognized where fine and very fine sand predominate.The core sediments were dominated by tychoplanktonic coastal-marine diatoms. The accompanying flora included stable marine-coastal taxa and allochthonous fluvial freshbrackish species. Three diatom zones (DZ) were established based on cluster analyses.The LCH site was significantly affected by Late Pleistocene and Holocene sea˗level fluctuations, and the progradation of the deltaic lobe during the last ca. 7,000 14 C yr. BP.Ancient tidal channels were flooded in the early Holocene postglacial transgression.Erosive and re˗working processes associated with the formation of estuarine channels, affected valves preservation, yielding with barren sections. Tidal flats and marshes have developed in the area during the late Holocene regression phase. The comparison of the sedimentary sequence with deltaic facies evolution models, confirm the presence of a hiatus, which masks the Holocene Maximum and highstand.

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“…Although the population density over the region is the lowest in Argentina (< 10 inhabitants km −2 ), these rivers have suffered moderate to intense human impacts over the last years. Unsustainable agricultural practices, oil extraction and transportation, the expansion of urban areas, salinization of soils, use of agrochemicals and sewage effluents insufficiently treated of domestic and industrial activities, increasingly contribute to the alteration of biophysical condition of the rivers (Abrameto et al 2017;Brunet et al 2005;Isla et al 2015).…”

Section: Regional Settingmentioning

confidence: 99%

“…It is only in recent years that diatom distribution studies in relation to environmental variables have been carried out in Patagonia, but it is still necessary to go further with a higher number of samples that allow a better fit of the inference models (Espinosa and Isla 2015;Vélez-Agudelo et al 2017). In this region, semiquantitative analyses based on diatoms have been used to reconstruct Holocene paleoenvironments in the Colorado, Negro and Chubut rivers (Escandell et al 2009;Fayó et al 2018;Isla et al 2015). However, diatom-based transfer functions have not yet been addressed in this area.…”

Section: Introductionmentioning

confidence: 99%

Diatom-based inference model for conductivity reconstructions in dryland river systems from north Patagonia, Argentina

2021

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Dryland river systems support a diverse aquatic biota in semi-arid and arid landscapes, but they are increasingly vulnerable to natural and human impacts. This study provides the first modern diatom training set (n = 38) from three dryland rivers in northern Patagonia, Argentina. The relationship between surface-sediment diatoms and contemporary environmental variables was explored using multivariate analyses. The results showed that surface-water chemistry varies among rivers in accordance with local-scale factors such hydro-climatic variability and anthropic activities. A total of 378 diatom taxa were identified but only 45 taxa occurred with relative abundances higher than 2% in at least one sediment sample. The Colorado and Negro rivers were characterized by high abundances of small tychoplanktic fragilarioids whereas the Chubut River was dominated by epiphytic and planktic taxa. The canonical correspondence analyses (CCA) showed that conductivity, pH and HCO 3 − were the main environmental variables governing diatoms distributions. A transfer function was developed for water conductivity using unimodal methods because of partial CCA and λ 1 /λ 2 ratio revealed that this variable had the largest unique effect on diatom variance. A weighted averaging (WA) model with tolerance downweighting and classic deshrinking provided a reasonably robust model (r 2 jack = 0.94 and RMSEP = 0.249 log 10 μS cm −1 ). However, the diatom-inferred conductivity values should be carefully interpreted because of the uneven distribution of sampling sites and the dominance of small araphid diatoms belonging to the genera Staurosira, Pseudostaurosira and Punctastriata. By their benthic habitat, the distribution of these taxa could be influenced by other factors as light and substrate in addition to water chemistry. The autoecological information achieved through this study will provide the basis for a better insight into the hydrological responses of the dryland rivers in northern Patagonia to climate and environmental changes.

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Avulsion at a drift-dominated mesotidal estuary: The Chubut River outlet, Patagonia, Argentina

Cited by 14 publications

References 23 publications

A paleo‐hydro‐geomorphological perspective on urban flood risk assessment

A paleo‐hydro‐geomorphological perspective on urban flood risk assessment

Holocene coastal evolution of Colorado River Delta based on diatom assemblages, Northern Patagonia, Argentina

Diatom-based inference model for conductivity reconstructions in dryland river systems from north Patagonia, Argentina

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