Reasons for the existence of the channel connectin the two lobes of the present Large Aral Sea are discussed. In situ measurements in 2005 show that differences between the measured depths and those contained in the available digital bathymetry of the lake are considerably different at the channel (7.5±0.9 m, at nine measurement stations along it) and at the northern part of the eastern lobe (1.6±0.3 m, at six stations from the western to the eastern shore). Differences in the misfits observed in the two zones are discussed and thought to be a consequence of the variation of the transversal area of the channel as it enters the eastern lobe, which would affect the flow velocity and thus the strength of the erosion process at the bottom. Field data together with satellite images have been used to modify an original digital bathymetry of the lake and have been implemented into a 3-D hydrodynamical model. A numerical simulation shows that a wind of 12 m/s blowing from the east (112°) generates velocities of up to 45 cm/s in the channel, allowing denser water from the eastern lobe (salinity: 132 g/kg) to flow about 38 km towards the fresher western lobe (salinity: 98 g/kg) in one day. The effect of the inflow on the vertical structure of the western lobe is also illustrated. Although nowadays the channel will be soon a thing of the past, in a more general context, the Aral Sea is presented as an example showing that geomorphologic and geophysical processes, along with hydrological and atmospheric processes, must be taken into account for short-term predictions

We thank D. Soloviov and S. Stanichniy (Marine Hydrophysical Institute, Ukraine), who kindly provided the satellite images used in this study. We are grateful to Professor Micklin and one anonymous reviewer for the interesting points they have raised in their review and for the opportunity to incorporate them in the text. This paper has been done within the frame of the NATO Collaborative Linkage Grant ESP-NR-NRCLG-982592. The work was also supported by the Russian Foundation for Basic Research and, partially, by the Spanish Ministry of Education and Science, grant FIS2008-03608

This paper has been done within the frame of the NATO Collaborative Linkage Grant ESP-NR-NRCLG-982592. The work was also supported by the Russian Foundation for Basic Research and, partially, by the Spanish Ministry of Education and Science, grant FIS2008-03608