Experimental study of the possibility of using an underwater acoustic wave gauge in freezing waters to measure the thickness of the ice cover

This work is devoted to the description of the experiment at the Gorky Water Reservoir in the Nizhny Novgorod region in the winter period of 2018-2019. As part of the experiment, an underwater pulsed sonar was installed at the bottom of the reservoir, the antenna unit of which was oriented vertically upwards to the water surface. Additionally, the underwater sonar is equipped with a two-axis inclinometer and a hydrostatic pressure sensor. The cable for power supply and data transmission was laid above the ice cover to the computer in a heated room on the pier. A computer on the pier is connected to the Internet and in real time transfers the measurement data to the consumer's computer. Data on the atmospheric conditions were obtained on the Volga Hydro-Meteo Observatory. As a result of the experiment, for the first time a comparison of two approaches to measuring the thickness of the ice cover using an underwater sonar was made. To assess the accuracy, control measurements of ice thickness were carried out by contact on different dates. The combination of two independent approaches may further allow remotely determining certain physical parameters of the ice cover, for example, the gradient of the speed of sound in the ice cover. The paper studies the possibility of using the autocorrelation function of the received pulse to determine the thickness of the ice cover. In addition, since the measurements were carried out in the reservoir during the spring flood, the possibility of measuring the reservoir level according to underwater sonar data was tested. As a result, there was obtained a discharge and accumulation of water in the reservoir.