Lake Ladoga Digital Bathymetric Models: Development Approaches and Insight for Limnological Investigations

The creation of digital bathymetric models (DBM) of lakes allows not only for storage of the data on depths and shorelines in a standard format, but also for the estimation of the major morphometric characteristics of the reservoirs. To calculate the water, thermal, and chemical budgets of large lakes, it is important to know their hypsometry. We developed a new digital model of Lake Ladoga, the largest European lake, which was done to identify and correct topographic data errors, as well as to identify more depth points. The produced bathymetric model of the lake allowed for the updating of morphometric characteristics. The lake-bottom grid of 0.5 × 0.5 km with 70,190 depth points of interest was produced using the kriging procedure with the mean error ME = 0.05 m and root mean square error RMSE = 5.6 m. The statistical characteristics of the lake depth and slope are determined on the basis of the advanced digital model of the lakebed relief. The form of the lake depression corresponds to the convex type (microtype) and bears some similarity to lakes Erie, Huron, Vanern, and Malaren. We describe how the bathymetric model has been developed and the morphometric characteristics of the lake have been corrected. We also discuss the results of its application in limnological investigations. A relationship has been established between surface water temperature, transparency and the bottom depths for the various seasons of Lake Ladoga.