Are We Done Yet? An Empirical Estimator for Level of Effort for Seafloor Surveys - Including an Estimate for the Full Survey of U.S. Waters

• Published in: Marine geodesy 2020-03, Vol.43 (2), p.87-104
• Main Authors: Greenaway, Samuel F., Batts, Amber, Riley, Jack
• Format: Article
• Language: English
• Subjects: Area; Benthic mapping; Echo sounding; Echosounders; Empirical analysis; Mathematical models; multibeam sonar; Ocean floor; ocean mapping; Parameters; Polls & surveys; Roughness; Surveying; Surveys
• ISSN: 0149-0419; 1521-060X
• DOI: 10.1080/01490419.2019.1705449

An estimate of the effort needed to survey some arbitrary area is a critical part of the planning efforts of any hydrographic office. We develop a simple, analytic model to estimate full coverage of an arbitrary seafloor area based on a fixed angular swath system such as a multibeam echosounder. This model incorporates one tuneable parameter to account for the overall efficiency of survey execution. We had expected this parameter to be strongly tied to seafloor complexity and thus regionally consistent; it was not. In fact, we could discern no strong relationship between this parameter and any variable investigated, including region, roughness, variability, depth, or survey size. We use this tuned model, including an estimate of uncertainty, to develop a model for survey effort, and apply the model to all of the U.S. waters. Accounting for areas already surveyed to modern standards, we calculate that we have surveyed 44% of the U.S. waters to modern standards by area, but only 18% by level of effort. To survey the remaining area to modern standards would take 12 million linear nautical miles of survey, or approximately 177 years of a single platform running continuously at typical survey speeds.