Bakhtiari

In this section the project is introduced in form of following items:

• Targets
• History and background
• Location and general layout
• River specifications
• Specifications of catchmnet area
• Dam location
• Features
• Side effects

 

 

 

 

 

 

Targets

• Generating hydroelectric energyTargets
• Preventing Bakhtyari River sediments from entering into dam reservoir and therefore increasing life-time of Dez dam and power plant
• Controlling floods, preventing its annual destruction and improving the conditions
• Safety measures in downstream of dam

 

 

 

 

 

History and background

History & background of the projectThe preliminary studies about Bakhtiari project started in March 1996 by Mahab Qods Consulting Engineers and continued for about 33 months. Related reports of the first phase of the project were handed over to the client (IWPC) in March 2000.
After electing the project manager in 2004 and transferring the management of the project from IWPC deputy department, negotiations related to electing the consultant of the second phase of the project continued and finally in May of 2005, IWPC handed over the consulting services of the project (including review and completion of the first phase studies, the second phase studies and preparing tender documents) to the following group of consultants:

• Moshanir Consulting Engineers
• Dezab Consulting Engineers
• Econo-Electrowatt (Swiss)/ Boyri joint-venture
• Stucky Pars Consulting Engineers
• with common and individual responsibilities. 

Location and general layout

Construction location of Bakhtiari dam and power house is in downstream of the Bakhtiari River in Lorestan Province, in south-western parts of Iran and in south-western domain of Zagros Mountains; in a zone with eastern longitude of 48°, 46' and 50" and northern latitude of 32°, 57' and 41"; which is situated in north-west of Tangpanj station on railway rout of Tehran-Ahwaz on Bakhtiari river.
Construction location of Bakhtyari dam has 50 km direct distance from upstream of Dez dam and 5 km distance from upstream the Sezar and Bakhtiari rivers’ cross section.

River specifications

Bakhtiari River is one of the main branches of Dez River which originates from the southern heights of Oshtorankooh Mountain and in the vicinity of Tangpanj station joins to Sezar River and forms Dez River.

Specifications of catchmnet area

Measurement of the catchment area at the site of the dam construction is about 6288 km2 and the average of catchment area height from sea level is 2212 m. Average annual discharge of Bakhtyari River at dam site is about 144.6 m3/s (according to testing period of 60 years) and average annual rainfall in this area is about 1117 mm. average slope of Bakhtiari River in its route is about 35 degrees.

Dam location

Dam locationAs it is shown in the image of project location; in the area of Karun and Bakhtiari catchment area, Bakhtiari dam will be constructed in upstream of (Dez) dam with a distance of 50 km to it.

 

 

 

 

 

Features

• The highest double arc dam of the world with the height of 325 m
• The biggest artificial reservoir of the country after Karkheh reservoir, with the capacity of 5.2 billion m3 at normal level
• No need to displace inhabitants of the reservoir area (due to the fact that this area is difficult to pass) after construction and water filling not many agricultural lands and no permanent village will go under water
• Power-plant capacity at 20% functional coefficient is
• 1500 W and its annual power generation is about
• 3000 GW/h
• Remarkable role of water supply and water regulation of the dam due to huge capacity of its reservoir
• Big economical indices of this project in comparison with economical indices of other projects, including hydro electric projects
• Controlling seasonal floods and improving security conditions in down stream of dam
• Preventing sediments of Bakhtiari river to enter dam reservoir and as a result increasing the profitable life-time of Dez dam and power-plant
• Remarkable increasing of water supply capacity in catchment area for better management of water resources and increasing volume of regulated water and as a result increasing the area of agricultural lands in downstream
• Possibility of generating the optimum energy in daily and annual peak periods of energy consumption

Side Effects

Bakhtiari dam and power-plant project, during implementation, will have important effects on regional job creation by employing regional man-power. Improvement of social, economical and cultural conditions in the region, providing opportunities for development and investment, improving the welfare level of the regional inhabitants, promoting the educational and health level and increasing the annual income, better use of tourism attractions of the region, increasing the share of the region in development of the country, improvement of the land transportation through access roads and increasing the added value of services in the region will be some of economical, cultural and social effects of this national project.

In this section the project basic information is presented in form of following items:

• Topography
• Meteorology
• Hydrology
• Flood
• Water quality
• Sedimentation
• Planning the water resources
• Geology
• Seismicity
• Dam reservoir

 

 

 

 

Topography

River length is more than 300 km and Bakhtiari dam has a catchment area of 6388 km2.

Item	Quantity
Catchment area	6388 km2
Average height of catchment area	2212m
Catchment area slope	35%
Average slope of the river	5.65%
Length of main river	300 km

 

Meteorology

Item	Quantity
Average annual rainfall in catchment area	1117 mm
Average evaporation of reservoir	1780 mm
Average annual temperature of dam construction site	21.2 °C
Probable maximum rainfall (PMP)	144 mm

Within the catchment area there are 5 meteorology stations, which although they do not have similar outputs, but generally their situation are estimated to be desirable.

Hydrology

The studied regional stations include Taleh Zang Dez, Tangpanj Sezar, Tangpanj Bakhtiari, Sepid Dasht Sezar, Zaz, Zard Fahrah, Ghelyan and Kazem Abad Kakolestan.

Item	Quantity
Catchment area	6388 km2
Concentration time	35 h
Average slope of the river	35%
Average outflow of water in Tangpanj station	144.6 m3

 

Flood

According to the existing data achieved from floods, most of the floods have taken place in spring and fall. The biggest observed flood in Bakhtiari River had a discharge of 4988 m3/s and occurred in Azar of 1994. Estimated discharge of floods with several return periods is presented in the following table:

Return Period	2	25	100	1000	10000
Peak discharge (m3/s)	2489	3910	5043	6857	8641

 

Water quality

Quality of Bakhtiari River water with ER and TDS are orderly 1090 maximum and 376 for drinking and agricultural use.

 

 

Sedimentation

Annual sediments volume of the area is estimated about 9 million m3.

 

 

 

 

Planning the water resources

Item	Quantity	Unit
Normal figures	830	masl
Minimum figures	785	masl
Reservoir minimum volume	2722	mmm
Reservoir volume at normal figures	5200	mmm
Reservoir profitable volume	2122	mmm
Annual inlet volume	4307	mmm
Water regulation volume	3688	mmm
Safety functional coefficient	21	%
Power house installation capacity	1500	Mw
Primarily annual energy	2368	GWH
Secondary annual energy	617	GWH
Output	92	%

 

Geology

The project location is wrinkled at north-west of Zagros sedimentary catchment area and is situated in Dezful low lands. This structure is situated mostly on Silica-lime of serok Sazand. Some of the important geological structures of the area are Gir Yoveh & Sia Klooh anticline, F1, F2 and F3 faults and kink bands. The penetration amount in left side is somehow high. Seismic topography tests results shows average velocity of 3200 to 2700 m/s in abutment and 500 m/s at foundation, which are not due to stone mass quality. Underground and galleries explorations and grouting tests are being carried out. 
The soil mechanic tests for determining the module of shape alternation and other physical specifications of stone mass are also being carried out.

Seismicity

Bakhtiari dam seismocity parameters are studied regarding seismography data of the region and general behavior of Zagros. With use of Deterministic method and Probabilistic method, the maximum amount of land horizontal velocity for
50-year return period (CE) is 0.15g, 145-year return period (OBE) is 0.23 g, 475-year return period (DBE) is 0.32 g and for 2000-year return period (MDE) is 0.45g. Maximum acceptable earthquake (MDE) for F3 fault is equal to 0.55 g which is equal to the vertical velocity of 0.429.

Dam reservoir

Item	Quantity
Total volume of reservoir	5200 million m3
Profitable volume of reservoir	3027 million m3
Water normal level	830 masl
Water minimum level	782.2 masl
Water maximum level	840 masl

Dam construction area is generally located on silica-lime Sazand of the Serok and according to the layers thickness and silica compounds, is divided into seven sub-units of Sv1 to Sv7. Some of the important geological structures are anticline of Giriveh and Siahkooh, F1-F3 trust, younger fault of F2, kink bands, forked clines and four joint systems at construction site. Slope and direction of layering slope, generally at downstream of anticline axis is N215/75 and in its upstream is N035/50. The issue of studying slope stability in current situation, without considering the artificial off-take of materials in axis area and other structures, does not show any difficulty and the abutments are stable in case of earthquake.

In this section the technical information of the project is presented in form of the following items:

1-Dam body

• Body specifications
• Reservoir specifications
• Diversion system
• Instrumentation
• Spillway
• Quarries and their specifications

2-Powerhouse

• General specifications of powerhouse
• Specifications of powerhouse equipments
• Specifications of powerhouse building
• Specifications of powerhouse outlet tunnels
• Specifications of powerhouse waterways

3-Technical specifications of post and switchyard

4-Water transfer tunnels

• Specifications of tunnels
• Intake structures
• Outlet structures

5-Access roads and bridges
6-Complementary operations

Body specifications

Item	Quantity
Dam type	Double arc concrete
Height from foundation	315 m
Crest length	434 m
Crest width	10 m
Foundation width	50 m
Total concrete placement of the body	3.1 million m3
Specifications of sealing system
Sealing method	Grouting curtain
Total length of grouting	58 km

Reservoir specifications

Item	Quantity
Total volume of reservoir	5200 million m3
Area of reservoir	58.7 km
Length of dam lake	59 km
Width of dam lake	1000 m
Normal level	830
Profitable volume of reservoir	3027 million m3

Diversion system

First tunnel
Location	Left abutment
Length of diversion tunnels	1151 m
Cross section	Circular
Tunnel diameter after lining	12 m
Discharge capacity	2090 m3/s
Type of lining	concrete
Second tunnel
Location	Left abutment
Length of diversion tunnels	1180 m
Cross section	U shape
Tunnel diameter after lining	13 m
Discharge capacity	1680 m3/s
Type of lining	concrete
Type an height of upstream cofferdam	RCC 51 m
Type an height of downstream cofferdam	RCC 25 m

Instrumentation

No date exists in this regard.

 

 

 

 

Spillway

Item	Quantity
Type of spillway	Gated with tunnel
Location	Right abutment
Type of gates	Radial
Numbers of gates	2
Diameter of tunnel	11 m
Discharge capacity	5830 m3/s
Dimension of gates	17.7 by 11 m

Item	Quantity
Type of spillway	Orifice
Location	Dam body
Type of gates	Radial
Numbers of gates	2
Diameter of tunnel	11 m
Discharge capacity	1510 m3/s
Dimension of gates	6.5 by 3.5 m

Quarries and their specifications

Totally around 3 500 000 m3 of sand material is needed for the project. In order to find the suitable quarry, it became evident that within the radius of 40 km around the dam location, no river quarry exists. Therefore three areas were considered for this purpose.
 
A- Excavation materials within the area of dam body
     and power house:
The volume of excavation materials of dam foundation, spillways, power house will reach 2 700 000 m3, from which only 60 percent (equal to 1 600 000 m3) will be used for sand material.
 
B- QU1 and QU2 quarries:
These quarries are located within 2 km range of downstream of dam axis and the volume of their material reaches 3.5 million m3.
 
C- Upstream quarries:
This quarry is located in the area of fourth unit of Saruk Sazand (upstream of batching plant location). It has a good volume of 4 million m3 suitable material.
The results of short term chemical and physical tests is generally satisfactory and the reactions of available material are alkaline-solicit and alkaline-carbonate. Therefore long term tests are being carried out in this regard.

General specifications of powerhouse

Item		Quantity
Type of powerhouse		Underground
Location		Left abutment
Capacity		1500 mw
Average annual generation		3000 million kw/h
Turbine type		Francis with vertical axis
Operation level	Minimum critical	770
	Normal	791
	Maximum	830

Specifications of powerhouse equipments

Item	Quantity
Numbers of turbine (main phase)	6 units
Numbers of turbine (development phase)	Being designed
Power of each turbine	250 MW
Maximum output	92 %
Height of turbine design	250 m
Design discharge of each unit	104.5 m3/s
Numbers of generators (main phase)	6 units
Numbers of generators (development phase)	Being designed
Type of generators	Being designed
Output power of each generator	250 mva
Rotation speed of generator	272.7 rotations per minute

Specifications of powerhouse building

Powerhouse cavern
Length	Width	Height
161m	24m	64m
Total volume of excavation		180 000 m3
Total volume of concrete placement		Being designed

Specifications of powerhouse outlet tunnels

In this regard no data exists.

 

 

 

Specifications of powerhouse waterways

In this regard no data exists.

 

 

 

 

 

Technical specifications of post and switchyard

Specifications of switchyard and 400 kv transfer lines
Post voltage	400 KV
Arrangement type of post	1.5 key
Numbers of  B	Being designed
Intake numbers	Being designed
Outlet numbers	Being designed
Area of post land	50 000 m2
Specifications of 400 post
Numbers of transformers	Being designed
Numbers of feeders of transformers	Being designed
Power of each transformer	Being designed
Numbers of outlet feeders	Being designed
Voltage of each outlet feeder	Being designed

Specifications of tunnels

Main Phase
Length of water transfer tunnel	504 m
Diameter of intake transfer tunnel	8 m
Diameter of outlet transfer tunnel	9.5 m
Type of lining	Concrete
Numbers of intake penstocks	6
Length of each penstock	51 m
Average diameters of penstocks	6.5 m

Development phase is being designed.

Intake structures

Item	Quantity
Numbers of intake	3
Maximum design discharge	104.5 m3/s
Design head	228.5-289.3 m
Numbers of  valves	2 series of 4
Type	Stop-log
Valve of intake structure	Radial
Width of valve	Being designed
Height of valve	Being designed

 Outlet structures

Item	Quantity
Numbers of intake	6
Maximum design discharge	Being designed
Design head	Being designed
Numbers of  valves	Being designed
Type	Being designed
Valve of intake structure	Being designed
Width of valve	Being designed
Height of valve	Being designed

Access roads and bridges

A- Internal access roads

1-Technical specifications of internal access roads

Name of the road	Average width (m)	Length (km)
Downstream road	9	8
Access road to crest and site stabilization area	9	10

2- Technical specifications of internal bridges

Name of the bridge	Width (m)	Length (m)	Type of structure
Sezar 3 bridge	9	190	Metal sheet shaft with concrete
Dez bridge	9	150	Metal sheet shaft with concrete
Doab bridge	9	40	Metal sheet shaft with concrete
Sezar 2 bridge	7	100	Metal sheet shaft with concrete
The bridge adjacent to diversion tunnel	6	90	Roof-truss
Entrance bridge to GL6 tunnel	6	75	Roof-truss

B- External access roads

In order to have road access to construction location of Bakhtiari dam, Board of Managers of IWPC approved to construct an access road from Khorramabad city to Tangpanj station. The distance between Khorramabad and Tangpanj station is 112 km.
The width of the said road is 7 m and other details are being designed. This road includes the following components:
1- Khorramabad- Cheshmak with the length of 32 km, including the existing asphalt road
2- Cheshmak- Emamzade Seyed Ali with the length of 25 km, including the existing road which need asphalt lining
3- Emamzadeh Seyed Ali- Tanghaft with the length of 35 km, 20 km of which is rehabilitation of the existing road and the rest should be constructed
4- Tanghaft- Tangpanj with the length of 20 km, that should be constructed

Complementary operations

In this regard no data exists.