INTRODUCTION AND BACKGROUND INFORMATION

LAKE BAIKAL
Lake Baikal is situated in the heart of south-east Siberia, in the eastern part of the Russian Federation near the Mongolian border, and it is surrounded by forest-covered mountain ranges. It contains a unique and highly diverse fauna and flora, with more than 1800 endemic species
It is the world's largest, deepest and probably oldest lake:
it is roughly 630 km long and on average about 60 km wide, it is over 1600 m deep and contains about 20 % of the total volume of surface fresh water on Earth, and it is estimated to be about 25 million years old
Lake Baikal water is characterised by its extreme low mineralisation, high transparency and purity.
The lake is fed by 336 inflowing rivers and drained by only 1 outflowing river. 
The lake occupies part of one of the very few presently active continental rift zones in the world: the Baikal Rift. The lake floor is subdivided into three major basins (Northern, Central and Southern), which are separated by bathymetric sills (Akademicheskii Ridge between the Northern and Central Basins, and the Selenga-Buguldeika Saddle between the Central and Southern Basins).
For these reasons, among others, Lake Baikal has been attracting visitors and scientists of different disciplines from around the world for many decades, and it was included on the UNESCO World Heritage List in 1996.

HISTORY OF BATHYMETRIC SOUNDING IN LAKE BAIKAL
The history of bathymetric sounding in Lake Baikal began already in 1798, when mining engineers E. Kopylov and S. Smetanin performed 28 depth measurements between the Angara River and the estuary of the Selenga River. One of their measurements gave a depth of 1238 m, which put Lake Baikal second in the ranking of the deepest water bodies in the world at that time. 
Based on a number of hydrographic expeditions lead by F.K. Drizhenko from 1902 to 1908, two documents were published: “Sailing Directions of Lake Baikal” and the “Atlas of Lake Baikal”. In these publications, only the depths in the coastal parts of lake were given with some detail.
In 1925, the Soviet Academy of Sciences initiated a long-term project, headed by G.Yu. Vereshagin, for studying the bathymetry of Lake Baikal. This initiative would eventually lead to the construction of a Limnological Station and a Limnological Institute. In the course of this project, the shallow-water sill of
Akademicheskii Ridge was discovered, as well as the deepest point of the lake. Based on those measurements, new bathymetric maps of Lake Baikal were produced (on scales of 1:300,000 and 1:500,000), and presented on the International Limnological Congress in Rome in 1934.
In 1962, after many years of continued bathymetric surveying, A.A. Rogozin and B.F. Lut in the Limnological Institute produced a new bathymetric map on the scale of 1:300,000. This map was later published as “Northern and Southern part of Lake Baikal” in 1973 and 1974 by the Head Department of Navigation and Oceanography of the USSR Ministry of Defense (GUNIO).
In the period between 1979 and 1985 GUNIO itself carried out a new, systematic program of bathymetric soundings of the entire Lake Baikal. Soundings were performed every 100 to 250 m in the shallower coastal waters, and every 1 km in the deeper parts, with a (radio)positioning accuracy of a few meters. The results of this last survey lead to the publication in 1992 of the 4-sheets
Bathymetric charts of Lake Baikal map series at a scale of 1:200,000.

OLD BATHYMETRIC MAP OF LAKE BAIKAL
Up to present, t
he most reliable bathymetric chart of Lake Baikal is the 4-sheets "Bathymetric charts of Lake Baikal" map series, published by GUNIO in 1992 at a scale of 1:200,000. This chart, however, still has a number of shortcomings:
1. The bathymetry is based on only a part of the original sounding data, 
2. The bathymetry is represented by interpreted and manually drawn contour lines,
3. The contour lines are at 100 m isobath intervals and for depths of over 1000 m only at 500 m intervals,
4. Recent investigations have shown that significant discrepancies may exist between the actual water depths and the readings on acousting sounding devices, which is due to the characteristic acoustic velocity distribution in Lake Baikal.

THE PROJECT: A NEW BATHYMETRIC MAP OF LAKE BAIKAL
In 1999 it was decided to create an international team of specialists and combine efforts and expertise to produce a new, more accurate bathymetric map of Lake Baikal. The aim was to re-compile the original sounding data that were used for the 1992 maps, to digitise them, to correct them using up-to-date, calibrated acoustic velocity information, to integrate them with as much as possible of the more recently acquired sounding data, and to produce a new, computer-generated, computer version of the Lake Baikal bathymetry map based on ALL available sounding data. 

This project was funded by INTAS (International Association for the promotion of cooperation with scientists from the New Independent States of the former Soviet Union), and the present CD-Rom contains the final results of this project.

THE TEAMS
Team 1: Renard Centre of Marine Geology (RCMG), Ghent University, Ghent, Belgium. 
- Marine and lacustrine geophysics and geology, seismic data, project coordination. 
- Researchers involved: M. De Batist, R. Hus.
Team 2: Consolidated Research Group on Marine Geosciences (CRG-MG), University of Barcelona, Spain. 
- Marine and lacustrine geophysics and geology, bathymetric, shoreline and topographic data integration and processing, map and 3D model generation.
 
- Researchers involved: M. Canals, J.L. Casamor.
Team 3: Limnological Institute of the Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russian Federation. 
- Hydrophysics, hydroacoustics, physical limnology.
- Researchers involved: P.P. Sherstyankin, L.N. Kuimova, B.F. Lut, O.M. Khlystov, E.V. Styagov, O.Y. Tolokontseva, V.V. Khokhlov
Team 4: State Science Research Navigation-Hydrographic Institute of the Ministry of Defense, St.Petersburg, Russian Federation. 
- Hydrography, hydrophysics, hydroacoustics,
bathymetry mapping.
- Researchers involved: S.P. Alekseev, A.N. Dobrotvorskii, V.S. Anosov, L.G. Kolotilo, A.A. Khrebtov, Y.F. Tarasuyk

USEFUL REFERENCES
- Bukharov, A.A., 2001. Baikal in Numbers. Baikal Museum, Siberian Branch of the Russian Academy of Sciences. 72 pp.
-
Galazy, G.I. (ed.), 1993. Baikal Atlas. Federal Agency for Geodesy and Cartography, Moscow [in Russian].
- USSR Ministry of Defense, 1992. Bathymetric charts of Lake Baikal. Chief Directorate of Navigation and Oceanography, Moscow, Scale 1:200,000. 


© the INTAS Project 99-1669 Team, October 2002.
For more information contact: Marc.DeBatist@UGent.be