Review of past and recent fluvial dynamics in the Beni lowlands, NE Bolivia

Plotzki, Anna; May, Jan-Hendrik; Veit, Heinz

doi:10.5194/gh-66-164-2011

Cited by 21 publications

(17 citation statements)

References 37 publications

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“…The central part of Llanos de Moxos is a floodplain subject to severe inundations that may inundate up to 150 000 km 2 affecting thousands of people and lead to human-economic losses equivalent to millions of U.S. dollars [21]. The low gradient and the impermeable clayey soils favour the inundation [22]. The main river is the Mamore river which is also the longest and most important Bolivian river.…”

Section: Study Areamentioning

confidence: 99%

“…Although the model does not consider some hydrological processes like infiltration or evaporation that could reduce the flood volume, those processes may be assumed as negligible for the purpose of the present study. Due to the low permeability of the soil [22] it is reasonable to assume that infiltration during this period is negligible. Fig.…”

Section: Performancementioning

confidence: 99%

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Application of 2D numerical simulation for the analysis of the February 2014 Bolivian Amazonia flood: Application of the new HEC-RAS version 5

Quirogaa

Kurea

Udoa

et al. 2016

Ribagua

181

111

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a b s t r a c tLlanos de Moxos are vast plains in the Bolivian Amazonia that are continually flooded by the Mamore river. The flood lasts for several days affecting important cities like Trinidad, drowning people, drowning cattle and swamping arable land. Because of the cloudy skies, remote sensing observations are limited to some areas and few days. Thus, there is huge uncertainty about characteristics of flood events and possible consequences. Two-dimensional (2D) numerical simulation proved to be an important tool for understanding flood events. The HEC-RAS model is one of the most popular hydraulic models. In 2014 a new version of HEC-RAS (HEC-RAS-v5) was released including 2D capabilities. The present study applied the new HEC-RAS-v5 to simulate the February 2014 flood event in the Bolivian Amazonia. The flood simulated shows good performance when compared with satellite image of the flood event. In addition, the simulation provides information like water depth, flow velocity and a temporal variation of the flood. Specific locations where water begins to overflow were identified. Over most of the flooded area the water velocity is lower than 0.25 m s −1 . During first ten days of the flood the flood extent increases rapidly. The flood depth allows identifying areas exposed to different hazard levels. The west plain of the Mamore river is the most exposed to the flood; it shows bigger flood extent, longer flood duration and deeper water depth. The flood that threatens the city of Trinidad originates in two locations; one located 32 km at the north and other located 10 km at the south west. The flood from the north gets close to Trinidad twelve days after it begins to overflow, while the flood from the south gets close to Trinidad seven days after it begins to overflow. Although the flood from the north is deeper than the flood from the south, the flood from the south begins flooded before the north. Thus, water borne and vector borne diseases may originate at the south earlier than the north. The city of San Javier gets covered by flood five days after the water begins to overflow. The study shows the applicability and the value of the 2D capabilities of the new HEC-RAS for flood studies. Llanos de Moxos son planicies de inundación en la Amazonia Boliviana que constantemente son inundadas por el río Mamore. Las inundaciones se prolongan durante varios días afectando importantes ciudades como Trinidad, ahogando gente, ahogando ganado e inundando cultivos. La visibilidad de imá-genes satelitales se ve limitada debido a la nubosidad. Por tal motivo se tiene un gran desconocimiento sobre las características de la inundación y sus posibles consecuencias. Simulación numérica bidimensional (2D) es una importante herramienta para simular y analizar inundaciones. El modelo HEC-RAS es * Corresponding author. uno de los más populares modelos hidráulicos. En octubre de 2014 la última versión de HEC-RAS versión 5 fue publicada con capacidades 2D. El presente estudio aplicó el nuevo HEC-RAS versión 5 para simular la inund...

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Section: Study Areamentioning

confidence: 99%

Section: Performancementioning

confidence: 99%

Application of 2D numerical simulation for the analysis of the February 2014 Bolivian Amazonia flood: Application of the new HEC-RAS version 5

Quirogaa

Kurea

Udoa

et al. 2016

Ribagua

181

111

View full text Add to dashboard Cite

show abstract

“…So far, most studies have focused on the Amazon River and its main tributaries in Brazil and Peru (summarized in Latrubesse, 2003). Even less information from marginal regions such as south-western Amazonia and the Llanos de Moxos (LM) lowlands of Bolivia is known, although several studies have reported large-scale river migrations of the Beni, Mamoré and Grande Rivers (Allenby, 1988;Dumont, 1996;Hanagarth and Sarmiento, 1990;Hanagarth, 1993;Lombardo et al, 2012;Plafker, 1964;Plotzki et al, 2011). Avulsive shifts along the Mamoré and Grande Rivers must have occurred in the mid to late Holocene (Lombardo et al, 2012;Plotzki et al, 2013), but no comprehensive geomorphological or chronological dataset is available for the older, Pleistocene fluvial system in the region.…”

Section: Introductionmentioning

confidence: 99%

Geomorphology and evolution of the late Pleistocene to Holocene fluvial system in the south-eastern Llanos de Moxos, Bolivian Amazon

Plotzki¹,

May²,

Preusser³

et al. 2015

CATENA

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In the Bolivian Amazon several paleochannel generations are preserved. Their wide spectrum of morphologies clearly provides crucial information on the type and magnitude of geomorphic and hydrological changes within the drainage network of the Andean foreland. Therefore, in this study we mapped geomorphological characteristics of paleochannels, and applied radiocarbon and optically stimulated luminescence dating. Seven paleochannel generations are identified. Significant changes in sinuosity, channel widths and river pattern are observed for the successive paleochannel generations. Our results clearly reflect at least three different geomorphic and hydrological periods in the evolution of the fluvial system since the late Pleistocene. Changes in discharge and sediment load may be controlled by combinations of two interrelated mechanisms: (i) spatial changes and re-organizations of the drainage network in the upper catchment, and/or (ii) climate changes with their associated local to catchment-scale modifications in vegetation cover, and changes in discharge, inundation frequencies and magnitudes, which have likely affected the evolution of the fluvial system in the Llanos de Moxos. In summary, our study has revealed the enormous potential which geomorphic mapping and analysis combined with luminescence based chronologies hold for the reconstruction of the late Pleistocene to recent fluvial system in a large portion of Amazonia. AbstractIn the Bolivian Amazon several paleochannel generations are preserved. Their wide spectrum of morphologies clearly provides crucial information on the type and magnitude of geomorphic and hydrological changes within the drainage network of the Andean foreland.Therefore, in this study we mapped geomorphological characteristics of paleochannels, and applied radiocarbon and optically stimulated luminescence dating. Seven paleochannel generations are identified. Significant changes in sinuosity, channel widths and river pattern are observed for the successive paleochannel generations. Our results clearly reflect at least three different geomorphic and hydrological periods in the evolution of the fluvial system since the late Pleistocene. Changes in discharge and sediment load may be controlled by combinations of two interrelated mechanisms: (i) spatial changes and re-organizations of the drainage network in the upper catchment, and/or (ii) climate changes with their associated local to catchment-scale modifications in vegetation cover, and changes in discharge, inundation frequencies and magnitudes, which have likely affected the evolution of the fluvial 2 system in the Llanos de Moxos. In summary, our study has revealed the enormous potential which geomorphic mapping and analysis combined with luminescence based chronologies hold for the reconstruction of the late Pleistocene to recent fluvial system in a large portion of Amazonia.

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“…Therefore, the interpretation of environmental and palaeo-environmental fluvial forms and palaeoforms is not always straightforward. Avulsive processes and the formation of DFS within the LM have been described in the case of the Beni River (Plafker, 1964(Plafker, , 1974Hanagarth, 1993;Dumont, 1996;Hartley et al, 2010) the Grande River (Hanagarth, 1993;Dumont, 1996;Lombardo et al, 2012;Plotzki, 2013) and the Mamoré River (Plotzki et al, 2011 (Fig. 3a) but the mechanisms behind these avulsions are controversial.…”

Section: Rivers and Palaeoriversmentioning

confidence: 99%

Neotectonics, flooding patterns and landscape evolution in southern Amazonia

Lombardo

2014

Earth Surf. Dynam.

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Abstract. The paper examines the role of neotectonic activity in the evolution of the landscape in southern Amazonia during the Holocene. It uses both new and published data based on the analysis of remote sensing imagery and extensive field work in the Llanos de Moxos, Bolivian Amazon. The study of the region's modern and palaeorivers, ria lakes, palaeosols and topography provides a strong case in favour of the thesis that the northern part of the Llanos de Moxos constitutes the southern margin of the Fitzcarrald Arch and that it has experienced uplift during the Holocene. The paper assesses the extent and timing of the neotectonic activity in light of the new data and reconstructs the evolution of the landscape since the late Pleistocene. The evidence suggests that at least two uplift events took place: a first uplift in the late Pleistocene, which caused the formation of Lake Oceano, and a second uplift during the mid-Holocene, which formed Lake Rogaguado. These two uplifts appear to be linked to the knickpoints observed close to the towns of Guayaramerín and Puerto Siles respectively. The backwater effect due to these uplifts transformed the region's major rivers in seasonal ria lakes, causing the deposition of thick organic clay layers along the Beni, Mamoré and Madre de Dios river banks. I argue that neotectonic episodes could have dramatically changed the drainage of the Llanos de Moxos, determining its flooding regime, soil properties and forest-savannah ecotone. These results stress the need for geomorphologists, palaeo-ecologists and archaeologists to take into account neotectonics when reconstructing the region's past.

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Review of past and recent fluvial dynamics in the Beni lowlands, NE Bolivia

Cited by 21 publications

References 37 publications

Application of 2D numerical simulation for the analysis of the February 2014 Bolivian Amazonia flood: Application of the new HEC-RAS version 5

Application of 2D numerical simulation for the analysis of the February 2014 Bolivian Amazonia flood: Application of the new HEC-RAS version 5

Geomorphology and evolution of the late Pleistocene to Holocene fluvial system in the south-eastern Llanos de Moxos, Bolivian Amazon

Neotectonics, flooding patterns and landscape evolution in southern Amazonia

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