Mohammadreza Babatabar - Faculty at the Islamic Azad University, Ayatollah Amoli Branc,Iran
Ebrahim Ghoreishi Tayyebi - Faculty at the Islamic Azad University, Ayatollah Amoli Branc,Iran
Mohammad reza Banihashemi - Assistant Prof. of Islamic Azad University, Ayatollah Amoli Branch, Iran
Behnam Valizadeh Mighaddam - Student of M.Sc. Degree at the IAU, Ramsar Branch, Iran,

This study presents a case study for design and construction of rubber dam for increasing capacity of Gorgan dam s reservoir. This dam is located on the Gorganrud River, near Gorgan city in Iran. The construction of this dam with 20 m height was started in 1967 and finished in 1970. It had 96 MCM volumes and had regulated about 175 MCM annually in end of construction. At start of operation, 24000 hectares of agricultural land was covered by this dam. Now, with accumulated sediment in the dam s reservoir, volume reduced to 45 MCM. To restor the initial volume of dam, design and install of six rubber dam on the platform with btruss strucre was considered. This structure joints to the exising concrete spillway. Important features of the proposed system are: - In the event of large floods, system returns to initial state. - Increase the volume of the reservoir by using volume between normal and maximum level at the absence of flood. - To consider key factors such as compliance with existing system, safety, easa of operation and maintenance. This new economical and efficient method has wide application to increase the capacity of existing reservoirs.

Gorgan dam, Rubber dam, Truss platform, Restoration