Damming of the Kara-Bogaz-Gol strait without side diversion of the flow

Conclusions

• 1. As a result of damming the strait, the inflow of water from the Caspian Sea into the Kara-Bogaz-Gol Gulf with a surface area of 10,000 km, which is a natural evaporator, was stopped.

• 2. To dam the strait with an erodible channel, a combined method of construction works was adopted and implemented, which consisted in narrowing the channel to a gap by hydraulic filling with sand and closing the gap by pioneer filling of low-strength stone and sand-concrete cubes. A special feature of this closure is that it was performed for the first time in hydraulic-engineering practice without side diversion of the flow and with the construction of a downstream of underwater sill in connection with this.

• 3. The experience of the closure construction works showed that the start of closure should be preceded by works on protecting the bed of the gap where the flow velocities increase intensely, considerably exceeding those permissible for the material being placed, in connection with which lengthening of the cofferdam should outstrip the rate of possible scour of the channel at the closure site.

• 4. The successful completion of the works on closing the channel of the strait was promoted by the downstream underwater sill, which made it possible to distribute the difference of levels and to maintain a water level in the lower pool above the natural levels, thereby compensating the absence of a structure for side diversion of the flow, which together provided closure of the gap at a difference of levels of 1.21 m, whereas the maximum difference was 2.03 m.