Siahbishe

Water quality

Average suspended particles within Alborz mountains area is altering considerably and is within an approximate range of 300 ton/year/km2 to 200 ton/year/km2.
On the basis of carried out measurements near the area of downstream dam (Chalus river in Zoghal bridge and Karaj dam), total amount of sediments are almost 750 ton/Year/Km2.
Carried out estimation by the Lahmeyer-Moshanir J/V shows an amount of 1.09 ton/m3 for dried weight of settled sediments (10% sand, 45% slime, and 45% clay).

Sedimentation

Annual average of sediment erosion in upstream reservoir is 1118 ton/km2 and in downstream reservoir is estimated to be 660 ton/km2. These results show that annual estimated erosion in upstream catchment area is 170% more than downstream catchmnet area.

Planning the water resources

According to the nature of pump storage dams, always a definite volume of water dislocate between upstream and downstream reservoirs. The important issues related to water resource planning in water filling and operation periods of such projects can be generally as follows:
 
1- Water filling period:
In this period generally the upstream reservoir is filled up to the maximum operation level and it is necessary to fill the downstream reservoir to the minimum operation level. Also the water rights and environmental issues of the mentioned reservoir downstream should be considered.
 
2- Operation period
In this period, parts of daily outflow of the river which is surplus to the upstream reservoir profitable volume, would be used in power generation system and other parts would be released for the minimum needed water rights of downstream area in the river. Also in downstream reservoirs, releasing the compulsory surplus water which is from upstream reservoir and releasing the inflow of downstream reservoir water from two rivers of Garmrudbar and Chalus for keeping the reservoir at the minimum operation level and preserving needed empty volume of reservoir are among the important issues.
According to the considerable volume of water surplus, which is evacuated daily through the bottom outlet of downstream reservoir, some arrangements can be considered such as turbine installation in the exit of bottom outlet for optimum use of water. 

Geology

Siahbishe project is located in north of Iran, between Tehran and Chalus cities and is situated in northern Alborz mountain domain which is part of the parallel anticline and synclines that form the southern boundary of the Caspian puddle. Siahbishe project is located in 4 kilometer distance of Candovan trust fault which is very important in technical structure of Iran geology.  It devides Alborz chain mountains into two northern and southern parts. In southern part, Karaj Sazand is expanded with Sansenozoic and in its northern part, where Siah-Bisheh project is located; the Sazands of first and second geology periods are expanded.

Seismicity

Some of the important faults of the Siahbishe dam structures are Candovan, Talaghan, northern Alborz, north of Tehran, Caspian and the main fault of the construction area. The biggest earthquake of this zone has been 7.4 in Richter scale and the biggest earthquake resulted from the nearest fault (Candovan) has been 7.2 in Richter scale.
The biggest earthquake velocity which is sustained into the construction area is about 0.59 g horizontal in downstream dam zone and 0.41 g vertical in upstream dam zone.
Achieved velocity for operation base level is equal to 0.25 g horizontal and for maximum design level is equal to 0.34 g horizontal.

Dam reservoir

Quarries and their specifications

General specifications of powerhouse

 Specifications of powerhouse equipments