A systemic approach to managing uncertainties in repetitive multibeam bathymetric surveys

Abstract

Multibeam Echo Sounder systems have enhanced the precision of modern bathymetric mapping, enabling the creation of high-resolution digital bathymetry models that characterise ocean and lake floors. However, the inferred models contain uncertainties that necessitate consideration, especially when conducting quantitative temporal comparisons. By exploring the results of two bathymetric surveys targeting a lacustrine delta, this study examines how geomorphological changes can effectively be interpreted through repetitive multi-temporal bathymetric surveys. We propose to use a workflow for Geographic Information System aiming at providing the basis for diverse studies that will implement bathymetric difference maps, also ensuring consistency. The proposed methodology incorporates the use of confidence intervals, based on the estimated uncertainties. The groundwork for interpretation relies on: (i) qualitative display using multivariate choropleth, (ii) quantitative assessment with the calculation of volumes of raw changes in cubic metres (m³), along with confidence intervals (±m³) and (iii) volumetric histograms accompanied with error bars.