1. A method for determining sea floor roughness using multibeam echosounder, comprising the steps of: i. providing backscatter, bathymetry and multibeam operational parameters; ii. removing system gain from the backscatter data to obtain real seafloor backscatter data; iii. calculating across track seafloor slope; iv. incorporating correction factor in actual beam arrival angles; v. calculating seafloor area; vi. measuring backscatter strength; vii. obtaining backscatter strength data at 1° angle; viii. obtaining power law parameters; ix. using the above-obtained parameters in a seafloor roughness power law model; x. splicing the multibeam backscatter data; xi. including sediment volume roughness model; and xii. verifying the validity of the composite roughness model.