METHODOLOGICAL ISSUES OF DETECTION AND MAPPING OF SUBSURFACE COLLECTORS OF DRAINAGE RECLAMATION SYSTEMS USING GEORADAR SURVEY

Purpose: to develop methodological issues of detection and mapping of subsurface collectors by the method of ground-penetrating radar survey. Materials and methods. The work was carried out on a section of the subsurface collector route located within the boundaries of the drained field of the Menkovskiy branch of the Agrophysical Research Institute (Gatchinsky district, Leningrad region). The dual-frequency ground-penetrating radar monoblock “OKO-3” with an AB-400/900 MHz antenna unit in a complete set with a tablet computer was used. Results. In general, favorable soil conditions for detecting a serviceable subsurface collector using the method of ground-penetrating radar survey in the “spring – summer” time interval are observed in the spring period, and for subsurface collectors passing through low relief elements – hollow thalwegs – also in the summer period. Detection of three or more local objects on a radargram – signs of subsurface drainage that form one straight line on the ground – is equivalent to one search pit made by mechanical means or manually at the location of the subsurface collector. The frequency range of the ground penetrating radar antenna that ensures detection of closed drainage is within 250–500 MHz. Conclusions. The efficiency of detecting a serviceable subsurface collector using the ground penetrating radar survey method, all other things being equal, depends on the presence of a moisture-saturated state of the adjacent soil layer and the presence of an air cavity in the subsurface collector tube. Fieldwork to detect a subsurface collector using the specified method involves the ground penetrating radar crossing the subsurface collector route in several places in a direction perpendicular to the subsurface collector. Work on mapping a subsurface collector based on ground penetrating radar survey data involves establishing the depth range of local objects identified on the radargram, their selection by depth and planned position – location on one straight line – and mapping by one of the points on such a line of the survey site(s).