Hydraulic modeling of Magdalena River using SOBEK

Jorge Luis Sanchez Lozano, Felipe Ardila Camelo, Jose Javier Oliveros Acosta, Wendy Dayana Ramirez Morales, Cesar Antonio Cardona Almeida, Cesar Ignacio Garay Bohorquez, Eelco Verschelling, Anke Becker, Migena Zagonjolli

Thursday 2 july 2015

11:30 - 11:45h at Amazon (level 1)

Themes: (T) Water engineering, (ST) River and coastal engineering

Parallel session: 11B. Engineering - River

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 257,000km2 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 wildlife species. These natural habitats 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. This has led to a lower acceptance of river related floodings. In the past, decision making with respect to flood management 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 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. For the first time in Colombian history, a numerical model of the entire Magdalena river 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 used to analyze water balances and hydrodynamics during different stages of 2010-2011 period. 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. 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.