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

Abstract

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...

Investigating the role of model structure and surface roughness in generating flood inundation extents using one‐ and two‐dimensional hydraulic models

“…Many past studies have shown 2D models to perform better than a 1D model with respect to hydrodynamics (Morales-Hernández et al, 2013;Quiroga et al, 2016;Şensoy et al, 2016), but in some cases, such as in steep topographies with no sinuous geometries, 1D models can give equally acceptable results. Application of 1D and 2D models for reaches with different topography and sinuous geometries in this study showed that 1D and 2D models can give equal results with the right combination of channel and floodplain roughness characterisation.…”

Analysis of exposure to vector-borne diseases due to flood duration, for a more complete flood hazard assessment: Llanos de Moxos, Bolivia

“…The downstream boundary condition was located not only at the downstream extreme of the Mamore River, but also at the borders of the model where the water is supposed to flow. More details about the calibration and performance of the model are described (Moya Quiroga et al, 2016).…”

Floodplain simulation for Musi River using integrated 1D/2D hydrodynamic model

“…The 1D flow model in most practice is generally used in the case where flow passes through prismatic channel. But, for non prismatic channel (i.e., channel with varying cross section and alignment) such as river, flow of dam break, or lateral flow through dike failure, and river overflow, the use of 2D flow becomes better model which results in accurate estimation [9,10]. Some of the examples of 1D and 2D in flood flow modelling were explained in detail in [11][12][13][14][15][16][17][18][19].…”

“…The illustration of general integrated 1D/2D flow model is shown in Figure 1. Some of the researches which were done previously concerning flood flow simulation with integrated 1D/2D model are presented in [10,20,21,[23][24][25]. Figure 3 shows the Musi River subsystems in the research location.…”

“…The model can simulate flood inundation by integrating 1D and 2D flow model. Indeed there are other hydrodynamic models which can be used such as XP-SWMM [26,27], TUFLOW [26], Flo-2D [28,29], SOBEK-OVERLAND FLOW [4], Delft1D2D [21], LISFLOOD-FP [30], and the familiar HEC-RAS [10,31]. But, Flood Modeller was applied as in the computation phase of 2D flow using solver alternating direction implicit (ADI) which was quick and stable [25].…”