Author(s): Jorge Luis Sánchez Lozano; Felipe Ardila Camelo; José Javier Oliveros Acosta; Wendy Dayana Ramirez Morales; César Antonio Cardona Almeida; César Ignacio Garay Bohorqez; Eelco Verschelling; Anke Becker; Migena Zagonjolli
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Keywords: 1D-2D Hydraulic Modeling; Magdalena River; SOBEK®
Abstract: This paper presents a model of the complex Magdalena River system, as an important step towards knowledge-based river management and flood risk management in Colombia, with due attention for both human and ecosystem interests. Rio Magdalena is the largest river of Colombia. It drains a catchment of 257, 000 square kilometers and is home to 38million people. Anthropogenic use of the floodplain areas conflicts with the natural value of these areas. On the one hand there are the extended ecosystems with unique wildlife species such as Crocodylus acutus, Iguana iguana and Prochilodus magdalenae. These natural habitats, especially the wetlands, partly depend on regular river floodings for their continued survival. On the other hand more and more human settlements are constructed in the floodplains, attracted by the many goods and services that the river provides (fertile land, navigation, fisheries, flat land for construction) .This has led to a lower acceptance of river related floodings. In the past, decision making with respect to flood management (either by prevention or adaptation) in Colombia has not always been based on sound knowledge of the river system as a whole, but rather on observations at a limited number of locations. To facilitate a transition towards a more knowledge-based decision making process, not only for flood management but also for issues related to navigability, the Magdalena river authority, Cormagdalena, has conducted a research project in order to improve their understanding of this river system. This research project focused on identifying and quantifying the major physical processes responsible for the inundations, as well as evaluating several mitigating flood reduction strategies. For the first time in Colombian history, a numerical model of the entire Magdalena river (800 kilometers) and its major tributaries was constructed and calibrated. The model consists of a one-dimensional component that represents the main channel system and a two-dimensional component for the floodplains and other inundation areas. This model was then used to analyze water balances and hydrodynamics during different stages of the major floodings that occurred in 2010 and 2011. A number of different strategies to reduce vulnerability to flooding were evaluated using the model. These steps provided the authorities involved with insight into the physical processes involved in the floodings and the feasibility of the proposed strategies. Furthermore, the modeling endeavor has revealed gaps in data collection and in the organization of the data collection process. This can guide future efforts to improve the model and its application for flood risk management. The numerical model seems to be an ideal tool to facilitate objective and knowledge based discussions with other stakeholders on the management of the river to reconcile wetland requirements and human needs.
Year: 2015