Cross sections for the 50-year flood, for Rio Nacaome, and Rio Guacirope and Rio Grande tributaries near Nacaome, Honduras. Water-surface elevations for an estimated 50-year-flood discharge for all three rivers at Nacaome were determined using HEC-RAS, a one-dimensional step-backwater computer program. The channel and floodplain cross section geometry used in HEC-RAS were developed from an airborne light detection and ranging (LIDAR) topographic survey of the area. The 50-year-flood discharge for Rio Nacaome, 6000 cubic meters per second, and for Rio Guacirope, 2300 cubic meters per second, and for Rio Grande, 4800 cubic meters per second were estimated using a flood-frequency analysis of a nearby gaging station. The area of inundation and depth of flood coverage was created with the HEC-RAS output and topographic TIN using HEC-geo-RAS software.