English Noun debris basin (plural debris basins) A facility to catch debris flows, to trap vegetative and sedimentary debris, such as gravel, boulders, branches, trunks; but allow water to drain; to prevent destruction from debris inundation and surge front downstream. Coordinate terms dam weir grizzly bars / grizzly water gate sedimentation pondWikiwand - on Seamless Wikipedia browsing. On steroids.