HYDRAULIC MODELING FOR LAHAR HAZARDS AT CASCADES VOLCANOS

The National Weather Service flood routing model DAMBRK is able to clo sely replicate field-documented stages of historic and prehistoric lah ars from Mt, Rainier, Washington, and Mt, Hood, Oregon. Modeled time-o f-travel of flow waves are generally consistent with documented lahar travel-times from other volcanoes around the world, The model adequate ly replicates a range of lahars and debris flows, including the 230 mi llion km(3) Electron lahar from Mt, Rainier, as well as a 10 m(3) debr is flow generated in a large outdoor experimental flume. The model is used to simulate a hypothetical lahar with a volume of 50 million m(3) down the East Fork Hood River from Mt. Hood, Oregon, Although a now s uch as this is thought to be possible in the Hood River valley, no fie ld evidence exists on which to base a hazards assessment, DAMBRK seems likely to be usable in many volcanic settings to estimate discharge, velocity, and inundation areas of lahars when input hydrographs and en ergy-loss coefficients can be reasonably estimated.