MODCEL vs. IBER: a comparison of flooding models in Riohacha, a coastal town of La Guajira, Colombia

Abstract

We compare two flood models applied to Riohacha. MODCEL, a conceptual model, had already been calibrated; IBER, a physically based 2D hydraulic model, has been calibrated and validated now with the same dataset used in MODCEL. MODCEL performs better according to several indicators. One cause of this difference is the low resolution of topography, a key input for IBER. Additionally, IBER is weak in representing hydraulic works, particularly concerning their real maintenance status, an information that MODCEL instead includes as the cells schematization is based on the actual flow directions reported by the people interviewed. This procedure however requires a deep insight into the actual behaviour of the physical system and a vast modelling experience. Furthermore, MODCEL software is less user-friendly than IBER. Both models, anyway, in the case at hand, capture sufficiently well the behaviour of urban flooding and the impact of interventions. Which is why they constitute key planning tools in the face of the flood problem in Riohacha and similar cases.

DEM Generation from Fixed-Wing UAV Imaging and LiDAR-Derived Ground Control Points for Flood Estimations

“…in the North (the coastline). The choice of the study area is based on two criteria: first, local interest due to its high exposure to severe storm flooding, as occurred in the course of El Niño-La Niña (2010/2011) [44,45]; second, the availability of previous hydrological and LiDAR elevation data, outlined by the red and blue lines in Figure 1. Additionally, the Riohacha context was selected as an emblematic case of emerging cities with high population growth rates and vulnerability to natural hazards thus raising scientific interest as shown in Nardini and Miguez [44].…”

Flood Modeling in a Coastal Town in Northern Colombia: Comparing MODCEL vs. IBER

“…Both MODCEL [12,13,24,26,27] and IBER [9,22,23,40,52] have been widely used for flood studies, although MODCEL is probably less known in the sectoral literature. Comparative studies between inundation models of the same or different nature are not a novelty in the scientific literature, but a specific exercise involving these two models to identify their complementarity was lacking.…”

“…We then decided to compare IBER performance to that of MODCEL, for the Riohacha case study, once calibration had been carried out with the same database and considering the same indicators of goodness of fit, in addition to versatility and ease of use. Some preliminary results of this study were published [24], but without details of the process carried out for the implementation of IBER. This process is not trivial because a series of choices have to be made in order to ensure the comparability of two modelling frameworks.…”

Contribuciones metodológicas para la obtención de información altimétrica requerida en la evaluación local de amenazas por inundaciones a partir de nuevas tecnologías geoespaciales

“…Estudios locales comparativos de MODCEL con un modelo hidrodinámico 2D (IBER 2D, Bladé et al 2014) utilizando los mismos datos de calibración, concluyen que MODCEL tiene un mayor rendimiento para recrear el evento extremo de 84 años, dado que puede trabajar con un modelo digital del terreno de baja resolución (Nardini et al 2018). Por los anteriores trabajos y su rigor científico, se justifica el uso de las profundidades simuladas del evento local de 84 años como datos hidrológicos para evaluar la utilidad de modelos derivados del procesamiento fotogramétrico de imágenes RPAS (Objetivo b de la tesis).…”

“…Este MDE constituye la base altimétrica utilizada en los estudios hidrodinámicos de inundaciones con el modelo hidrodinámico cuasi-2D "MODCEL" para el proyecto "Adaptación Urbana Verde". El uso de este MDE con MODCEL, se justificó frente a otros modelos hidrodinámicos 2D más complejos que requerían un mayor nivel de resolución espacial (de Oliveira et al, 2019;Nardini et al, 2018;Nardini & Miguez, 2016). Dicho modelo de elevaciones fue corregido verticalmente con respecto a la red geodésica oficial del instituto geográfico IGAC a partir de observaciones externas con el fin de asegurar la calidad altimétrica del mismo (Fundación CREACUA 2014).…”