Geomorphological aspects of the flash flood of January 31 1994 in the basin of the Rio del Fraile and their associated phenomena

Abstract

Flash flood and related mass wasting events that occurred on January 31, 1994 on the Rio Fraile in Central Western Colombia had severe consequences for the town of Florida and its inhabitants. Twenty eight people died, 40 were reported lost, 180 were injured and 70 families lost their homes. Additional damage included destruction of a bridge on an important highway, wreckage of the power supply system and the obstruction of the aqueduct that provides water to the town. As for similar events in the past, once the flood occurred most institutional efforts went into helping people to relocate their homes in safer areas, but little attention was paid to the understanding of the causes, magnitude and recurrence interval of the event. This paper describes the event and also evaluates the intrinsic aspects that favor the occurrence of the phenomena on this basin; we give arguments to suggest the use paleo-hydrology data obtained from on older torrential deposits, which are abundant in the basin as the best alternative to calculate the magnitude and frequency of events of this nature.