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Using inland waterway transport is economically justified in any region of the world, however to this day inland waterway freight and passenger transportation in Russian Federation constitutes not a big fraction of the total amount of traffic even as the total length of navigational waterways in Russia is more than one hundred thousand kilometers and the length of today valid navigational waterways is more than seventy thousand kilometers. There are two major reasons for this situation. The first one is a lack of quality up-to-date nautical electronical charts covering navigable sections of inland waterways. Providing the region with valid electronical cartographic resources over a short period of time is possible only by introducing innovative technologies. The second one is navigational and hydrographic support quality. In order to resolve both issues simultaneously, authors suggest using automated hydrographic sweeping systems, allowing for prompt conduction of inland surveys, dragging and sweeping at rather low operating costs. Additionally, it will provide an opportunity for partial automation of the chart manufacturing process like automated hydrographic survey systems do, which in turn will lead to a wider use of the region's inland waterways by cargo and passenger vessels in the future. This paper describes issues that can be solved by means of automated hydrographic sweeping systems, equipment used by the systems, and basic algorithms for calculating and correcting measured parameter values (level, antenna lowering, calibration, vessel subsidence in shallow waters, distance between the satellite navigation system and the echo sounder antennae), as well as techniques for the evaluation of the accuracy of depth values received by an echo sounder.

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The accuracy of various interpolation methods, used by specialists when working manually or technically implemented in software when plotting bottom relief on navigation maps of inland waterways, namely nearest neighbor interpolation, triangle based interpolation, bilinear interpolation and biquadratic spline interpolation, is analyzed in the paper. The study was conducted during the process of creating an electronic navigational chart of the Northern Dvina River. The aim of the study is to determine the interpolation method that guarantees the minimum deviation of the calculated values from the original values and the rendering of the least number of artefacts. In existing cartographic and geoinformation software, only interpolation methods based on regular grid calculations are used. In this study interpolation is performed on an irregular grid since depth sounding is carried out using a single beam echo sounder, and the depth grids obtained using this type of equipment are always irregular. This makes it possible to ensure the highest possible accuracy of the initial measurement during interpolation. The accuracy of the performed interpolation is verified by dividing all depths into two parts (longitudinal and transverse tacks) and calculating the depth values at longitudinal tacks using interpolation. The maximum discrepancies of up to 50 cm are detected when performing nearest neighbor interpolation. The minimum discrepancies of less than 10 cm are detected during biquadratic spline interpolation. According to the results of the study, biquadratic spline interpolation is the best method for building digital models of the bottom relief that can then be used to plot bathymetry on navigational charts.