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In this section the project basic information is presented in form of following items:
In the basin of Chamshir Regulating-Diversion dam, maximum, minimum and average elevation are equal to 3705.97 m, 242.39m and 1440.95m, respectively. According to the isoclines maps, average slope of the basin is evaluated about 18.5%.
Geographically, the study area is located at the range of 50˚ 17´ to 50˚ 55´ of east longitude and 30˚ 01´ to 30˚ 20´ of north latitude. In another word, the aforementioned area is a mid-catchment locating between Chamshir Dam and diversion-regulating dam which discharged to Persian Gulf and Zohreh is the main river of this basin. In the aforesaid area, two meteorological stations, Babakalan and Bonepir, with 11 and 8 years statistics respectively and 2 stations of Water Authority, Bonepir and Bibijanabad, with 28 and 45 years statistics are existed. All those stations are rain gauges expect Bibijanabad which is evaporation station. Due to the location of Bibijanabad station and by comparison of quantitative and qualitative statistics of this station with other station inside and outside of the study basin, Bibijanabad was chosen to represent local meteorological parameters. Annual rainfall during the 45 year period in this station is equal to 385.5 mm. Precipitation quantity, in higher and lower rainfall years, are reported about 755.5 mm and 141 mm in 1993-1994 and 1998-1999, respectively. The highest rainfall months of the year are December and February and the lowest ones are June, July, August and September. According to the statistics of representative station, annual temperature in study area is about 23.2 °C. The average monthly temperature for coldest months of the year, in January and February, is equal to 11.8 °C and for hottest month of the year, in August, it is about 34.6 °C. Based on maximum daily temperature recorded during the months of June, July, August and September, the maximum temperature has been reported more than 50 °C. In January and February as the coldest time of the year, the temperature has fallen to 3 degrees below zero. Overall, the study area is located at semi-arid climate.
Physiographic features of the aforesaid mid-catchment are presented in the table below:

940.25 km2


217.47 km

Gravelius coefficient


Equivalent rectangle length

99.26 km

Equivalent rectangular width

9.47 km

Main channel length

91.05 km

Main channel slope


Mean elevation of basin

528.54 m

In order to calculate the flood, the regional analysis and SCS methods are used. Assuming the dam construction, flood of the mid-catchment between the dam and diversion-regulating dam with area of 940.25 km2 has been checked, in which case, after the flood routing at the situation of dam reservoir, amount of flood at dam location must be added to the presented results of basin. Flood design with return periods of 2 to 500 years has been calculated based on rainfall-runoff model.
Return Period (year)


10 20 50 100 200 500



543.9 744.3 1057.2 1336.9 1662.1 2168.0
Water quality
The chemical quality of the water at the diversion-regulating dam location has been estimated based on the Gachsaran quality reagent station on the Zohreh river. Through 429 collected samples from 1967 to 2011, the equivalent mean discharge sample of 45 years (1966 to 2011) at mentioned station and qualitative parameters of this sample is presented in the table below.
Catchment: Mid-Zohreh
River: Zohreh
Station name: Gachsaran (Bibijanabad)
Station Code: 241721002
Yield (m3/s)


EC PH CO3 HCO3 CL SO4 Total Anions Ca++ Mg++ K+ Na+ Total Cations S.A.R Na% C-S


66.00 2193.81 3395.0 7.8 0.0 3.2 24.0 8.2 35.4 8.6 4.0 0.00 23.0 35.6 9.1 64.6 C4-S4
Water quality
Quantity of sediments in the basin has been calculated according to the Chamshir dam studies, analysis and generalizes the sediment to the study basin and also PSIAC method. In the PSIAC method, role and effect of 9 important parameters on soil erosion and sediment production of the catchment is evaluated. The 9 factors including topography, vegetation, land application , upland soil erosion, channel erosion and sediment transport, surface geology, soil, climate and surface currents. Duo to this method, the weight of sediment in the mid-catchment of Chamshir dam is 1133.98 ton/km2 and total tonnage of sediment at location of Chamshir diversion-regulating dam is estimated 928022 tons per year.
Planning the water resources
Annually, Zohreh river catchment is discharged over 3 billion cubic meters of surface flow into the Persian Gulf. The first branch of the river is called Ardakan (Sheshpir) and then renamed to the Fahlian. Zohreh river after connecting with Kheirabad enters to the Zeidoon plains and then reredirects to the south at south of Aghajary and finally passes through the Hendijan. In the present situation, volume of the annual water passing through the location of diversion-regulating dam, which is located after the Chamshir and Cham-e-bastan dam, approximately is equal to 2041 million cubic meters per year. At the present situation, water right quantity from main branch of the river to location of diversion-regulating dam is related to the drinking water of Sepidan and water rights of Ardakan, Fahlian and Chamshir which totally, is equal to 180 million cubic meters per year. Thus, the total hydro potential of Zohreh river to the location of diversion-regulating dam equals 2221 million cubic meters per year. According to studies performed after the completion of upstream projects such as Chamshir, Cham-e-bastan, Sheshpir and Parsian dams, the total amount of surface flow has crossed at the location of diversion-regulating dam, is estimated over 1853 million cubic meters, from this amount 514 million cubic meters per year are directed to the Leiravi plain in Bushehr province. According to the monthly distribution of water requirement at Leiravi plain, the largest volume of required water is related to April, and is equal to the 72.2 million cubic meters and minimum monthly requirement is related to December and equals 18.04 million cubic meters.
Planning the water resources
Geologically, the study area that is included the location of diversion-regulating dam, rout of pipeline system, location of hydroelectric power plant and irrigation-drainage network is situated at folded Zagros zone and at the end of littoral plain (Khuzestan). At folded Zagros zone, Paleozoic, Mesozoic and Tertiary sediments with the same slope, high thickness sedimentation and passing the development stage (platform, geosynclines and after orogenic) have become to folded form of nowadays and each of these stages have their own characteristics and sedimentation features.
Based on geological division of Iran, the study area is located in the Zagros tectono-structural units. Tectono-structurally, Zagros folded-faulted belt is divided to some regions. Section of aforementioned area is located in range of high Zagros that is called thrust Zagros or Zagros crushed zone. width of this section of the Zagros is between 10 to 70 km and its length is about 1300 km. This section of the Zagros are included some features like closed anticlines and/or overturn folds with South West direction. Southwestern boundary of this section is constituted by groups of young faults. A mountain folded belt is located at southwestern boundary of aforesaid part of Zagros. Width and length of this belt in Iran is 250 and 1300 km, respectively which continuance of that is traceable in northern Iraq and southern Turkey. Also, this belt is limited to front Zagros fault at southwest. It’s noted that this fault is the southern limit of the Asmari limestone outcrops. According to the seismotectonic map of Iran and the occurred earthquakes, it seems that the project span is seismically active. Based on studies and catalogs of earthquakes, seismic events in the area are basically low depth type.
Dam reservoir
Useful volume, approximate length and average width of diversion-regulating dam reservoir are 3.75 million m3, 4 km and 125.5m, respectively. Normal water level of the lake is 185.8 m from sea level.
Dam reservoir