Author(s): F. Pereira Joao; M. Silva Jose; M. Holly Forrest; Forrest Holly
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Keywords: 1-D mathematical modelling; Unsteady flow; Movable bed; Sediment transport; CHARIMA; Mondego river
Abstract: Mondego is the largest exclusively Portuguese watercourse (240 km) with a river basin of 6670 km2. As in other major river basins in Portugal (e. g., Tagus, Douro) significant river mining occurred in Mondego in the decades of 1980 and 1990. Remediation measures recommended a study of Mondego river sediment transport and its long-term bed evolution. This research was aimed at a critical reach of about 65 km, between Alva tributary mouth and Mondego’s estuary, in Lower Mondego. A 1-D unsteady-flow numerical model, CHARIMA (Holly et al. 1990), was selected, with the support of its main author. To test and implement the model, field data from the last twenty years were used. The modeling of this case study revealed the potential and flexibility of CHARIMA, as well as areas needing further development. River sediment transport and long-term bed evolution were predicted for the hydrological period of 2004/05 to 2020/21. Situations of local degradation and aggradation as well as the global behaviour of the reach were analysed. The results were compared with the results obtained by CENOR and DHVFBO (2004) for the same Mondego reach with the 1-D steady-flow numerical model HEC-6 (USACE 1993).
Year: 2007