Karkhe

 

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
• Commencement and Termination of the construction of Karkhe Project

Targets

• Providing water for irrigation of 340 00 Hectares of Downstream fields
• Controlling destructive floods and preventing their damages
• Generating hydro electric power
• Decreasing hydraulic gradient

History and background

Studies of the water and soil resources development project of the Karkhe River catchment started since 1335 by an American Corporation. Subsequently, some Iranian and foreign companies carried out studies in relation to the dam construction on this river which is as follows:

• Study the recognition phase of the irrigation development of the upstream basin in 1345
• Complementary studies by two Iranian and foreign Corporation in 1347
• Study the potentiality of Karkhe reservoir dam by Consulting and Civil Engineer of Iran Water Resources in 1358
• After Islamic revolution victory, some studies carried out by the “Jahad Construction Co.”
• Complementary studies of the first phase of Karkhe dam were carried by the Mahab Ghods Co. in 1367

Location and general layout

Location & general layout of project Karkhe dam is constructed in 21 kilometer of west north of Andimeshk city in Khuzestan province. This project is located in 48 degree and 8.7 minutes of eastern longitude and 32 degree and 6.29 minute of northern longitude.

 

 

 

 

 

River specifications

Karkhe River is originated from the middle regions and south western of Zagros chain mountains in west and north western of the country and after passing a distance about 900 kilometer along the north, heads toward the south and finally in common border of Iran and Iraq, it reaches to the Hoorolazim lagoon. Karkhe River is the third greatest river of Iran after Karun and Dez Rivers in case of water outflow.

Specifications of catchmnet area

Karkhe catchment area with the 43000 square meter width is located between 46 degree and 57¢ to 49° and 10¢ of eastern and 31° and 48¢ to 34° and 58¢of northern latitude.

Dam location

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Features

• The greatest dam in Iran history
• Having the biggest dam lake of the country

Commencement and Termination

• Initiation the operation: March 1991
• Diversion of Karkhe river: October 1995
• Dam refilling: February 1999
• Inauguration of dam body construction and spillway: march 2001
• Operation of the first unit of the powerhouse: September 2002 (August 22 of 2002 at 19:30)
• Operation of the second powerhouse unit: December 2002 (21 January 2002, at 17:40)
• Operation of the third powerhouse unit: July 2003 (27 may 2003 at 22:00)
• Complementary Operational Commencement of Karkhe Dam: April 2004
• Operation of spillway valves: April 2004
• Inauguration of Dashteabbas water transferring tunnel: 21 April 2005

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

Karkhe River, in the above of hydrometer station of Paypol, passes from the middle of the hills and high grounds and enters in to the Khuzestan plain. Karkhe River, at the upstream of the dam axis, changes its direction about 90° and the dam lake is located at the right side of the axis. From the viewpoint of River slight steep, dam lake has a remarkable volume. The steep of reservoir is mild. Steep of the left abutment is too harsh but at the right side it became mild. In the left coast, at the distance of 200 Km to the dam axis, a relatively great flood channel enters into the river and in the downstream also there is a smaller flood channel that the dam power station is located in the left side of it. Besides, there is another flood channel in the upstream of the dam axis, on the right side.

Meteorology

Catchment area of the Karkhe River, for its great extension, has various climates. Khuzestan plain and southern area of the Catchment is semi-dry with mild winters and long and hot summers, whereas northern parts and alpine regions have cold winters and mild summers. Temperature degree in this area changes from -25° to maximum 50°C. Annual average of rainfall in this area changes from 300 milliliter to 800 milliliter.  Karkhe catchment area generally has Mediterranean climate. Annual average rainfall amount in dam location is about 290.6 milliliter. The annual average of temperature in dam location is about 24.6 degrees centigrade and the highest and lowest temperatures are -4.2 and 53.6 degrees centigrade. Annual evaporation of the water free level is about 2079 millimeter and the amount of Annual average humidity is 45.5%. The annual average of freezing days in the project location is 4.5. Average velocity of wind is 2.5 M/S and the maximum is 41.2 m/s directing west. The annual average of sunny hours is 2762.7.

Hydrology

There are 47 hydrometric stations on the Karkhe River. The area of Karkhe catchment area in Paypol station is about 42239 square kilometer. The average annual discharge volume in Paypol station is more than 5916 Million m3 and the average annual long-term outflow in this station is equal to 188 m3/s. More than 64% of annual water flow occurs in January to May.

 

 

Flood

Generally, floods occur in humid months of the year, tha is October to April. Big floods mostly occur in March, April and May.

Return period	5	10	20	50	100	200	1000	10000	P.M.F
(Year)
Discharge (m3/s)	2900	3735	4665	6075	7240	8465	11690	17560	23670

 

Water quality

Samples quality shows that the water of this area is healthy potable. But in dry months, when the outflow of the river reaches to its minimum amount, the TDS amount is high and causes some limitations for agricultural usage.

 

 

Sedimentation

For normal figures of 220 masl, total sedimentation in a period of 50 years is estimated about 1730.5 million tones and in case a 100-year hydrograph is considered, the total amount of sedimentation for a 50-year period will reach to 2147.3 million tons. The reservoir suitable lost volume, caused by the above sedimentation is equal to 1443 million square meters.

 

Planning the water resources

Total potential of irrigating lands in Karkhe dam system is about 340000 hectares. The annual average volume of regulated water is about 3306.42 million m3. The average amount of hydro-electric potential energy of Karkhe dam power-station is 934 GW/h in a year and functional coefficient of Karkhe power-station is equal to 27%.

 

 

Geology

Karkhe dam is located in south western of Zagros Chain Mountains. High hills of this region consist of soft sediments of Aghajary and Bakhtiary Conglomerates. The main parts of the upstream of the reservoir consist of Aghajary components which is a combination of sand stone layers and lichen. The upper parts of this component consist of sandstone and lichen which made this area suitable for creation of under-pressure reservoirs.

 

Seismicity

Karkhe Dam structure is located in Zagros, which is one of the most active seismocity regions of Iran. Around the dam structure there are several faults that Lahbory fault has the maximum amount of quaking potential in this project.

Area of ground quake	DBL	MDE
Maximum horizontal velocity (according to g)	0.23	0.28
Maximum horizontal velocity (according to g)	0.12	0.18

 

Dam reservoir

Reservoir volume on operation level of 220 meter: 5.6 Billion m3 (before sedimentation)
Usable volume of reservoir is 3.9 Billion m3 (after sedimentation)
Water level at the time of flood occurrence is at most 230.9
Lake area at operation level of 220 m is 162.47 km2
Length of the lake at operation level of 220 m is about 60 km

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

Dam type:	Rock fill with clay core	Crest width:	12 m
Height from foundation:	127 m	Foundation width:	1100 m
Crest length:	3030 m	Total body volume:	1.6 million m3

 

 

Reservoir specifications

Total volume of reservoir:	5.6 billion m3
Area of reservoir:	162.47 km2
Length of reservoir:	60 km
Normal level:	+220 m

 

Diversion system

Number of diversion tunnels:	One culvert with 4 entrances
Length of diversion tunnel:	790 m
Cross Section:	Octagon
Type of lining:	Concrete
Discharge capacity:	3680 m3/s at the level of 161.7 m

 

Instrumentation

Including 23 Sections of Instrumentations

 

 

 

Spillway

Location:	Left bank	Discharge capacity:	18260 m3/s
Type of spillway:	OG with gated chute	Type of gates:	Crossed
Dimensions of gates:	15 by 18 m2	Number of gates:	6

 

 

Quarries and their specifications

Resource	Area (km2)	Depth (m)	Destination to the dam (km)	Volume (Million m3)	Type of material	Using location
G1	4	5-10	4-8	20	GW-GP	Shell-drainage-transition layers- concrete materials
G2	0.8	2	11-14	1.75	W-GP-GC	Shell-drainage-transition layers- concrete materials
G3	8	3	9-12	2.5	GW-GP	Shell-drainage-transition layers- concrete materials
C1	2.5	3-5	10-13	6.2	GH	Dam core
Chenare quarry			57			Upstream riprap

 

General specifications of powerhouse

Type of power plant:	Over ground hydroelectric	Average yearly energy generation:	934 Giga Watt /hour
Capacity of power plant:	400 Mega Watt	Type of turbine:	Francis with vertical axis

 

Specifications of powerhouse equipments

Number of turbines:	3 units	Number and type of generators:	3 vertical synchronal units
Power of each turbine:	136 Mega Watt	Outlet power of each generator:	140 Mega Watt
Maximum output:	95%	Nominal voltage of each generator:	13.8 KV
Design height of turbine:	93 m	Speed of rotation of each generator:	150 rotations per minute
Water discharge from turbine at maximum load:	159.54 m3 at the max level of reservoir	Nominal current of generator:	8000 Ampere
Manufacturer of turbine:	Harbin	Manufacturer of generator:	Elin
Average flow of water for electricity generation:	145 m3/s

 

Specifications of powerhouse building

Length of the building	Width of the building	Height of the building
117.5 m	53 m	55 m

 

 

Specifications of powerhouse outlet tunnels

One culvert with six entrances and an open-cut channel, with the following specs
Length of the culvert	60 m	Level of the outlet water	115 masl
Length of the channel	300 m	Width of the channel	6.15 m

 

Specifications of powerhouse waterways

Length of each penstock:	457-446-436 m	Type of lining:	Concrete and metal
Number of penstocks:	3	Average diameter of penstocks:	6.2 m

 

 

Technical specifications of post and switchyard

In this regard no data exists.

 

 

 

Specifications of tunnels

Shape and numbers of intakes:	4 octagon intakes	Volume of used concrete:	223000 m3
Diameters of each intake:	5 by 10.5	Level of intake:	113 masl
Length:	790 m	Level of stilling basin:	100 masl
Type of lining:	Concrete	Discharge capacity:	3680 m3 at the level of 161.7 masl
Volume of excavation:	1.5 million m3

 

Intake structures

Length of 32 m and width of 30.6 m	Stopping the first tunnel with the central gate
With 4 inlets	Stopping the second tunnel with the central gate
Inlet tower	Stopping the third tunnel with the fixed rotation gate
Stopping gates	Stopping the fourth tunnel with the rolled gate

 

Outlet structures

stilling basin with the length of 128.5 m and the width of 35 m

At the level of 100 masl

Three series of stop-log gates

 

Access roads and bridges

Name of the road or bridge	specifications
L1 road	With the length of 11.7 km from Dehloran
L2 road	With the length of 21.8 km from Andimeshk
Access road to the connecting bridge	With the length of 3.4 km
Access road to Dashtabbas tunne	With the length of 15 km from Dehloran
Existing road on the right bank	With the length of 19 km from Dehloran
Connecting bridge to L1 and L2 roads	With the length 205 m and the width of 5 m

 

Complementary operations

No data exists in this regard.