The December 1999 3-day storm along the north-central coast of Venezuela initiated widespread landslides that evolved into mud and debris flows in watersheds throughout the coastal State of Vargas. One of the many urbanized alluvial fans impacted by flooding and debris flows was the community of Tanaguarena at the mouth of the Cerro Grande River canyon. The Institute of Fluid Mechanics, University of Central Venezuela, is currently designing flood and debris flow mitigation structure on this alluvial fan. A three-phase analysis for replication of of the replicating the 1999 flood was implemented. First, the December 1999 rainfall distribution, intensity and runoff were investigated. Then the 3-day flood hydrograph was estimated with the HEC-1 hydrologic model. Finally, a two-dimensional flood routing model FLO-2D with the capabilities of simulating hyperconcentrated sediment flows was applied to route the flows over the alluvial fan. With this calibrated model, flood mitigation can be designed for a selected frequency design flood event. Results indicate that the FLO-2D model can accurately replicate the 1999 flooding on the Cerro Grande fan.
