Khersan 3

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

 

 

 

 

 

 

Targets

• Generating of more than 1100 Giga Wat Hour  of hydroelectric energy annually
• Regulation of the Khersan River flow to increase the energy generated by downstream dams
• Control of the Khersan River destructive floods
• Storage of approximately 1158 million cubic meters of water for generating hydroelectric energy
• Breeding of different types of aquatic
• To provide an appropriate place for recreation and tourism attraction

 

 

History and background

• First phase studies: Mahab Qods Consulting Engineers
• First phase revision studies: Joint Venture of Abanpajuh, Parsab Tadbir and Stucky Consulting Engineers in 2004
• Second phase studies: Joint Venture of Abanpajuh and Stucky Consulting Engineers in 2007
• Geotechnical studies and material strength tests
• Construction of the residential-official camp: 2005-2007
• Surveying activities of Dam site, reservoir and…
• Physical - chemical tests of borrow areas
• Performing regular measurments of flow and water level of boreholes
• Water monitoring tests to assessthe chemical characteristics
• Hydraulics Model of project on the scale of 1:40 (Biggest one in Iran)
• Power network studies includes load distribution, short circuit studies and network stability studies
• Cadastre maps of the dams reservoir
• Aerial photoes in the scale of 1:10000 by alteracam RGB camera

Location and general layout

Location & general layout of projectKhersan 3 dam is located in higher part of Khersan River in Charmahal va Bakhtiari Province in south-west of Iran and north-east slopes of Zagros Mountains in an area with eastern longitude of 50°, 58¢, 25² and northern latitude of  31°, 14¢, 50² near Talaye and Atashgah Villages with approximate distance of 50 km from Lordegan City.
Accessibility to Khersan 3 dam site is possible through Esfahan-Broojen-Lordegan or Shahrkord-Lordegan roads and through asphalted road of Lordegan-Sardasht-Atashgah. Atashgah-Lordegan road, located in 300 m east of construction site, is terminated to Khersan River.

 

 

 

 

 

 

 

 

 

 

River specifications

Khorsan River is one of the branch of Karun which is originated from “Tang Sorkh” and “Kanedodehse” Mountains in 43 km south-east of Yasuj City and 15 km north-west of Ardakan Fars City. This branch continues its way with the name of “Boshar” River toward north-west. While passing through western valley of “Tang Sorkh” this river irrigates “Bardzard” and “Tang Khoshk” Rivers. It then joins “Tang Sorkh” River or “Mahmood Beigy”, one kilometer west of “Tang Sorkh” Village and then enters the valley, which is located in the middle of “Toop Abdollah” (in the east) and “Pazanan” Mountains (in the west).
In the entrance of mentioned valley it irrigates “Deh Tuly” Village and after joining another eastern river joins the water of “Dely Safadr” Valley and then “Vazag” River and flows toward “Kalgeh” Village through eastern valley of “Kharkelon” Mountain.
After passing from “Sartang” Village in 3 km distance of “Deh Sheikh” Village it joins the river of “Abza” Valley and after crossing “Deh Kohneh” and “Sarsoor” Villages, it reaches “Dorah” Village.
In the eastern part of this village, it mixes with “Gerdab” River which is passing from “Abdehi” Valley and with the name of “Garm” or “Khersan” River, enters Lordegan region in Charmahal va Bakhtiari Province. Length of Khersan River is 180 km and the height of its sources is 2900 masl.

 

Specifications of catchmnet area

Khorasan river catchment area is one of the sources of Karun River catchment area. Main part of the mentioned area is mountainous and the altitude of its highest point in Dena Mountain is about 4437 masl. Average height of catchment area is 2398 masl.
 

Summary of physiographic specifications of khersan 3 Dam

Location	Area	Circumference (km2)	Average height (masl)	Length of river (km)	Average gradient of river(%)
Khersan 3 axis	7733	570	2398	180	0.9

 

Dam location

Dam locationAs it is shown in the following figure, khersan 3 Dam is constructed on Khersan River in upstream of Khersan 2 and Khersan 1 Dams.

 

 

 

 

 

 

 

 

Features

• A thin double arc concrete dam with height of 195 m and concrete placement volume of 1100 000 m3 for dam body
• Reservoir volume of more than 1158 million m3
• Installation capacity including four units of vertical Francis turbine with total capacity of 400 MW
• Annual generation of 1121 Gwh electrical energy
• Equipped with free spillway on dam crest and two deep outlet channels embedded in middle part of the dam body
• Equipped with a diversion tunnel in left bank with internal diameter of 12.5 m and length of 768 

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

Topography and morphological status of Khersan 3 construction valley has provided suitable conditions for construction of an elevated double arc concrete dam in a way that average lateral topography gradient is more than 60° and maximum height from the river bottom to the banks is estimated to be more than 350 m.
 

 

Meteorology

Average annual temperature in dam site is about 17°C. Average annual evaporation from water free level in Dam Lake is about 1674 mm. Average annual comparative humidity is 47% and average amount of annual rainfall in the region of catchment area is estimated to be 645 mm. Due to expansion of the catchment area and existence of high chain mountains of Zagros, climate of this region is changeable in its different parts, in a way that south to north-west of the region is moderate semi-humid to cold semi-humid, slopes and north eastern area of the region is semi-dry and cold and finally upper heights of the region have cold and humid climate.
In order to carry out meteorological studies, psychometric and pluviometer stations (totally 67 stations) of Ministry of Energy and synoptic, climatology and pluviometer stations of Meteorology Organization (totally 32 stations) have been used.
Meteorology.

Hydrology

The studied catchment area is located in south-west of the country in an area between geographical latitude of 30°-15¢ to 31°-30¢ and geographical longitude of 50°-55¢ to 52°-00¢. Main part of Khersan catchment area is mountainous and altitude of its highest point in Dena Mountain is 4413 masl. The average height is 2398 masl and the measurement of this area to Khersan 3 recommended dam location is about 7733 km2.

 

Summary of physiographic specifications of Khersan 3 Dam

Location	Area	Circumference (km2)	Average height (masl)	Length of river (km)	Average gradient of river (%)
Khersan 3 axis	7733	570	2398	180	0.9

Hydrometric stations status

The most important hydrometric stations located next to the project site are:

1-Barez hydrometric station:

this station is located between geographical coordinates of 50°-23¢ to 31°-32¢. Measurement of catchment area of this station is equal to 8941.7 km2 and its height is 815 masl. It is a first grade station that is equipped with scale, poltelfric and liminograph. This station was established in 1958-1959 and now has totally 49 years of statistic records.

2-Kata hydrometric station (Marbare River):

this station is located in geographical coordinates of 51°-16¢ to 31°-11¢. Measurement of catchment area of this station is equal to 4060.6 km2 and its height is 1530 masl. It is a first grade station that is equipped with scale, poltelfric and liminograph. This station was established in 1971-1972 and now has totally 33 years of statistic records.

3-Pataveh hydrometric station:

this station is located in geographical coordinates of 51°-16¢ to 30°-58¢. Measurement of catchment area of this station is equal to 2714.2 km2 and its height is equal to 1465 masl. It is a first grade station that is equipped with scale, poltelfric and liminograph. This station was established in 1971-1972 and now has totally 33 years of statistic records.

Discharge status of River at Project Site

Khersan River originates from the heights around Yasuj Province which includes Dena Peak with the height of 4413 m. The river has two important branches of Marbareh and Garmrud. These two branches, near a place called Sarsur, join each other and form Khersan River. The area measurement of this river near Barez station is equal to 8941.7 km2. According to the project’s hydrological studies, discharge of Khersan River near the reservoir and power house of Khersan 3 dam is equal to 2971 million m3.
Hydrology.

Flood

Regarding the existing statistics of maximum daily flood from hydrometric station of Barez in 1956-1957 and also accessibility of daily maximum flood statistics in hydrometric stations of Kata and Pataveh since 1971-1972, the information of floods with different return periods at the project site are as follows:

Return period	2	5	10	20	25	50	100	1000	10000
Maximum discharge (m3/s)	815	1292	1596	2073	1961	2493	2467	3771	4690

 

For determining PMF of Khersan River at the dam site, experts have benefited from estimated PMP on the basis of storm of March 1997 and also rainfall pattern distribution. Maximum probable flood peak on this basis is estimated to be 6799 m3.

Water quality

According to the Wilcox Curve which is drawn for the selected stations, it is observed that Khersan River water quality at the site of Khorasan 3 Dam is C2-S1 and according to Shuler Diagram drawn for selected stations the quality of water is suitable for drinking.

 

 

Sedimentation

Average sedimentation amount of Khersan 3 Dam catchment area is equal to 366 tons/year/km2. This volume would give us an amount equal to 2,360,000 m3 of annual sedimentation entry into dam reservoir; therefore 50-year entry sedimentation in dam reservoir would be equal to 118 million m3.

 

 

 

Planning the water resources

Normal level of Khersan 3 Dam is equal to 1432 masl and minimum level is equal to 1400 masl. Therefore with benefiting from a power station with installation capacity of 400 MW it would generate annually 682 Gwh of secure energy and also 439 Gwh of the secondary energy.
Summary of project’s water resources planning is as follows:

Dam crest height (masl)	1440
Maximum normal level of water (masl)	1432
Minimum normal level of water (masl)	1400
River-bed height (masl)	1262
Lake’s volume at normal level (million m3)	1158.4
Lake’s volume at minimum level (million m3)	520.1
50 years sedimentation volume (million m3)	118
Level of sedimentation volume	1355.8
50-year sedimentation level in the vicinity of dam’s body	1308
Installation power (MW)	400
Output coefficient (%)	28
Hours of generating peak energy	6.7
Annual generated secure energy (Gwh)	682
Annual generated secondary energy (Gwh)	439
Total annual generated energy (Gwh)	1121

 

Geology

Dam site and lake are located at the geological zone of Zagros Chain Mountains. The general procedure of geological structures is north-west to south-east and includes a series of compressed synclines and anticlines. Dam site is located on “Laki” north-east anticline whose general lithology consists of lime and lime-maronite stones of Asemary components. Asemary components at the dam site are divided in two upper and lower Asemary.
Layering gradients with the angle of 35° at the dam site is toward upstream, which besides the layering system it has also affected some of stone blocks joints. In the construction boundary beside the mentioned joints, about 35 faults with different lengths are identified.
Permeability in left abutment and central foundation is estimated high and stone blocks in right bank are also considered to be highly permeable.

 

Seismicity

Khersan 3 dam site is located in Zagros Mountains. Existence of faults such as Randegy Jalaleh, Ablarun, Shoram, Chirbun, Zeitun, Dalun, Rig, Sefidar and Dena in 200 km distance of construction site indicates the high seismic potential within the boundary of dam site. Naghan earthquake in 1977 in 75 km distance of site with the magnitude of 6.1 MS and with intensity of IV is highly remarkable.
Most important historical earthquakes of the Project domain are: earthquake of Ahwaz in 840, earthquake of Khuzestan in 1052, earthquake of Arajan in 1085 and earthquake of north-east of Shiraz in 1824, which most of their magnitude had been between 5.8-6.8 MS and their distance to the construction site had been within the range of 88 to 211 km.
Powerful land movement’s parameters include horizontal and vertical maximum velocity, which are estimated in three levels of designing base, maximum design and maximum credible, are as followed:

Earthquake level in design	Horizontal maximum velocity (g)	Vertical maximum velocity (g)
Design base level (DBL)	0.3	0.21
Maximum design level (MDL)	0.39	0.28
Maximum credible level (MCL)	0.63	0.52

 

Dam reservoir

Specifications of level, volume and height of Khersan 3 dam reservoir according to plans with the scales of 1:2500 are shown in the following table. According to this table volume of Khersan 3 Dam reservoir at the level of 1432 masl, equal to 172 m of height, is 1158 million m3. Dam reservoir would occupy an area equal to 33.85 km2.

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

• Dam body

1. Body specifications
2. Reservoir specifications
3. Diversion system
4. Instrumentation
5. Spillway
6. Quarries and their specifications

• Powerhouse

1. General specifications of powerhouse
2. Specifications of powerhouse equipments
3. Specifications of powerhouse building
4. Specifications of powerhouse outlet tunnels
5. Specifications of powerhouse waterways

• Technical specifications of post and switchyard
• Water transfer tunnels

1. Specifications of tunnels
2. Intake structures
3. Outlet structures

• Access roads and bridges
• Complementary operations

 

Body specifications

Item	Quantity
Dam type	Double-Curvature Concrete Arc
Height from foundation	195 m
Crest length	470 m
Crest width	6 m
Foundation width	40 m
Total volume of the body	1,100,000 m3

Reservoir specifications

Item	Quantity
Total volume of reservoir	1158.4 million m3
Area of reservoir	24.5 km2
Length of dam lake	40 km
Average width of dam lake	400 m
Normal level	1432 masl

Diversion system

Item	Quantity
Numbers of diversion tunnels	1
Length of diversion tunnel	768 m
Tunnel diameter	13.9 m
Open-cut excavation volume	130000 m3
Underground excavation volume	115000 m3
Cross section	Circular
Type of lining	Concrete
Tunnel diameter after lining	12.5 m
Discharge capacity	1893 m3/s
Type, height and volume of upstream cofferdam	CSG, 44 m and 104000 m3
Type, height and volume of downstream cofferdam	Rock-fill, 10 m and 35000 m3

Instrumentation

List of monitoring equipment		QUANTITIES
Symbols	EXPLANATION	LEFT	CENTER	RIGHT	TOTAL
PS	Anchor point for direct pendulum	2	2	2	6
PB	Pendulum BOB	2	2	2	6
PF	Inverted pendulum float	2	1	2	5
PA	Inverted pendulum Anchorage	2	1	2	5
PMS	Pendulum measurement station	10	10	10	30
JID	Directional joint meter	10	12	10	32
TC	Theodulite console in gallery	20	10	20	50
CT	Concrete temperature thermometer (Total – number of embedded instruments)	15	20	15	50
WT	Water temperature thermometer	3	5	3	11
AT	Air temperature thermometer	3	5	3	11
CL	Clinometers	3	6	3	12
SMR	Strong motion recorder	2	3	2	7
EX	Extensometer	6	4	6	16
PM	Vibrating Wire Piezometer	9	6	9	24
RW	Reservoir water level indicator	-	1	-	1
DM	Seepage measurement Station (V notch)	2	3	2	7
TB	Terminal Box for Thermometer Cables	1	1	1	3
OP	Geodetic Observation target	6	-	5	12
CP	Geodetic control point	10	4	10	24
TA	Target on downstream face of dam	8	10	8	26
UG	Uplift Gauge with pressure-meter	-	5	-	5
SP	Stand-pipe piezometer (casagrande)	30	-	30	60
ADAS	Automatic Data Acuisition System	-	-	-	1
MS	Meteorological Station	-	-	-	1

Spillway

Item	Quantity
Type of spillway	Free
Discharge capacity	6300 m3/s

Quarries and their specifications

	Fine-graded material	Coarse material	Rock quarry
Location	Near Sardasht Village	Upstream waterway of Sardasht Village	Dam excavations and lateral structures
Transportation distant	20 km	27 km	2 km from deposit area
Volume	600000 m3	600000 m3	1600000 m3
Type	Layered clay	Layered sand-clay	Lime and Marne-lime

 

General specifications of powerhouse

Item	Quantity
Type of powerhouse	Surface hydroelectric
Capacity	400 mw
Average annual generation	1121 GWh
Turbine type	Vertical Francis

Specifications of powerhouse equipments

Item	Quantity
Numbers of turbine	4 units
Power of each turbine	100 MW
Output in nominal condition	94.5 %
Height of turbine design	177 m
Discharge of turbine in nominal condition	80 m3/s
Numbers of transformers	4 units
Nominal power of each transformer	128 MVA
Nominal second voltage of transformer	410 KV
Numbers and type of generators	Vertical synchronic
Output power of each generator	118 MVA
Nominal voltage of each generator	13.7 KV
Rotation speed of generator	300 rotations/minute
Nominal current of generator	4000 A
Basic nominal voltage	13.7 KV
Cooling system	Water and air

Specifications of powerhouse building

Length of the building	Width of the building	Height of the building
75 m	24 m	48 m