Diagnostics and identification of anomalous zones of trunk pipelines at underwater crossings using digital elevation model

The article considers the issues of geodetic support for monitoring the technical condition of main gas pipelines underwater crossings (MGPUC). The purpose of the research is to increase the accuracy of determining the depth of the gas pipeline underwater crossings of main gas pipelines by taking into account the zones of faulty location of the pipeline (anomalous zones) and the bottom surface above MGPUC. The main problem of determining the technical condition of the gas pipeline underwater crossing is the difficulty of determining the depth of the gas pipeline due to the influence of external factors (soil, constructions and communications) on the measuring equipment (underwater trace detectors). The study indicates the accuracy of building digital elevation models (DEM) of the bottom, from which the calculation of the protective roll over the gas pipeline, which affects the determination of the technical state, and the causes of anomalous zones, as well as the ways of their determination. The variants of increasing the accuracy of calculating the depths of the gas pipeline location taking into account the DEM data are studied. The approach to definition of the method of spatial interpolation for construction of the bottom DEM according to the echolocation data depending on the surface curvature changes is offered. The authors note the interrelation of determining the criterion of technical condition of under-water crossing with the accuracy of DEM construction and determination of the spatial position of the pipeline. The proposed approaches are aimed at reducing the influence of the systematic part of the error and increasing the accuracy of the depth of occurrence, which is an urgent task.