Remote Estimation of Water Body Depth Based on the Date of the Beginning of Ice Formation Using a Hydrophysical Model

The aim of the study is to develop a methodology for estimating the average lake depth based on remote sensing data of ice conditions using methods of modelling thermohydrodynamic processes in a freezing water body. The primary tool f or accomplishing this goal is the FLake — lake hydrophysical model. Using meteorological data from the ERA5 reanalysis for the coordinates of the selected water body, the model calculates the time of ice formation on the water body at different values of its average depth. Based on remote sensing data, the date or time interval of water body freezing estimated. If data for several years are available, the depth of the water body specified by averaging the values for each year. At discreteness of satellite images with an interval of several days, the range of average lake depths corresponding to the time interval between satellite passes over the water body is determined. Information on the onset of ice phenomena was obtained based on the results of thematic interpretation of Sentinel‑2, Landsat‑7, 8, 9 satellite images for the period from 2016 to 2023. The methodology tested on four groups of morphometrically- studied lakes located in permafrost zone of Eastern Siberia in the Republic of Buryatia and Transbaikal Territory. The results of approbation showed a satisfactory correspondence between the calculated and measured values of the average depth of the lakes under consideration. The quality and quantity of satellite images in the study region limited the accuracy of the proposed methodology. The prospects of the methodology lie in the possibility of fully remote assessment of water resources of poorly studied regions of the country.