On the eve of the Great Patriotic War, a group of hydrogeologists from TsNIGRI — M. M. Vasilievsky, G. A. Lebedev, N. F. Pogrebov, N. A. Revunova, B. K. Terletsky and N. I. Tolstikhin — compiled a general hydrogeological map of the USSR on a scale of 1:5,000,000, with an explanatory note that was being prepared for publication. The war prevented the publication of the work. Most of the compilers of the map and the note — N. F. Pogrebov, M. M. Vasilievsky, G. A. Lebedev, B. K. Terletsky — died. Over the past decade, regional hydrogeology in the USSR has made great strides, but the explanatory note to the map has not lost its interest and significance, therefore, with the permission of the director of VSEGEI, Prof. L. Ya. Nesterov, it is printed in this edition. The map cannot be published by technical reasons. Instead, a hydrogeological zoning scheme is attached, compiled on the basis of a geological map on a scale of 1:7,500,000, published in 1950, taking into account the hydrogeological zoning maps prepared by M. M. Vasilievsky and G. A. Lebedev.
