The most important positive effect of the proposed project is to improve the quality of drinking water and water supply situation to improve the quality of life, health, and welfare of people of the southern residential areas in Hormozgan Province, Iran.
Furthermore, the Operation phase has advantages like: controlling flood regimes and reducing water particles in the dam lake, making microclimates and improving the weather conditions. Employment rate will be increased and it is predicted that the migration of many jobseekers from the area will be reduced. The long-term positive effects of the project will result in improving the quality of social environment and general welfare of the people and the economy of this area. Improving the quality of water sediments and microclimate of Dam Lake can result in other positive effects such as attraction of various animal species, especially birds.
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
- Intro
Targets
The main objectives of Sarney Dam and Water Supply System Project are:
- To improve the quality of life of people of the city of Bandar Abbas and neighboring villages by securing and supplying 19 MCM per year of safe drinking water.
- To supply about 9 MCM of water per year for recharging and balancing the underground aquifer downstream of the dam on the river course to improve the water availability and avoid any negative impact on the environment.
History and background
- Feasibility Studies (Phase I); Tamavan Engineering Consultants, 1997
- Design Reports, Environmental and Social Impact Assessment (Phase II); Tamavan Engineering Consultants, 2007
- Civil works for Access Road awarded to Jian Contracting Company, 2008
- Review of Detailed Design Reports (Phase II); Tamavan Engineering Consultants, 2011
- Signing Istisna’a financing and Executing Agency contracts between Islamic Development Bank and Hormozgan Regional Water Company, 2012
- Civil works for Diversion Tunnel awarded to Payab Kowsar Company, 2011
- Changing the Executing Agency from Hormozgan Regional Water Company to Iran Water and Power Resources Development Co., 2015
- Civil works for Dam Construction awarded to Melli Sakhteman Co., 2015
- Starting the bidding procedure for construction of Conveyance Pipeline and Water Treatment Plant, 2015
Location and general layout
The project is located in the south-eastern part of Iran in Hormozgan Province, at 27-7' to 27-52' north latitude and 57 -51' to 57 -14' east longitude- about 23km from the Minab Town and about 136 km south east of important port city of Bandar Abbas.
River specifications
- Sarney River is considered as a part of Persian Gulf and Oman Sea Catchment Area, originated Bashagard Mountains and flows into Oman Sea.
- The length of the River to the construction site: 85 km
- Average Discharge Capacity of the River: 1.49 cubic meters per second
- Special long-term sediment flow rate: 500 tons per year per square meter
- Average annual rainfall in construction site: 245 mm
- Average evaporation from water surface: 1609 mm
- Average annual inflow to Sarney Dam: about 46 million cubic meters
- Maximum Discharge takes place in winter and fall, respectively
- The river is mostly dry in the summer with very little Discharge
- During the studied period, the highest amount of Discharge has been in February 1992 with the amount of 97 million cubic meters
- The lowest Discharge of zero was observed from April to August.
Specifications of catchmnet area
- The upper parts of Sarney catchment area (northeast catchment) includes the southern slopes of the Bashagard Mountains known as the origin of Sarney River
- This part of the catchment area starts from a height of 2043 meters above sea level and covers up to the height of 800 meters above sea level.
- Middle parts of the catchment area include low-lying hills, and then this area has become a desert, and finally connects to the sea.
- The slope of the catchment area equals 3.6% in horizontal direction, 4.24% in vertical direction, and 3.94% in average.
- The average height of Sarney Dam catchment area equals 702 meters above sea level and the height of the highest and lowest points of the catchment area are 2043 and 97 meters, respectively.
|
Catchment |
Area (Km2) |
Average Height (m.a.s.l) |
Average Slope (%) |
River Length (Km) |
Height of the highest point (m.a.s.l) |
Height of the lowest point (m.a.s.l) |
|
Sarney Dam |
706 |
702 |
3.94 |
85 |
2043 |
97 |
Dam location
Access to the Project site is possible through Bandar Abbas- Minab- Jakdan Road, and then the access road to the dam site which is approximately 12 km.
Features
- Earth-fill Dam (gravel with vertical clay core) with a height of 52 meters.
- A water treatment plant with a capacity of 2 cubic meters per second
- Gravity conveyance pipeline with a length of 38 km (Steel pipes and GRP, 1m in diameter) from intake to the water treatment plant.
- The project is financed by the contribution of Islamic Development Bank (IDB) and Government of Iran (GOI).
In this section the project basic information is presented in form of following items:.jpg)
- Topography
- Meteorology
- Hydrology
- Flood
- Water quality
- Sedimentation
- Planning the water resources
- Geology
- Seismicity
- Dam reservoir
Topography
Dam will be constructed on sandstones, shale, siltstones and conglomerate interlayer layers. The above sediments are rocks cut by Sarney River at the direction from south-southeast to north-northwest.Asymmetric Valley with topographic slope of 22 to 23 degrees in the right side is unleveled and rugged, each step 30 to 40 meters in length and 15 to 25 meters in height up to the elevation of 145 meters above sea level and then prolongs with a 10 degrees mild slope to the elevation of 160 meters above sea level.
Considering the crest height, and with regard to the hills existing in 50 and 225 meters distance from the dam axis, there are two height limitations of 100 and 50 m width as well as 10 and 5 m height. In case of constructing a dam with more 45 meters height, there will be over flow through the right bank of the lake. To prevent this, two small and relatively shallow emergency spillways will be constructed.
Unlike the right side, the dam axis in the left side has a regular slope of 33 degrees up to the elevation of 170 meters above sea level. River bed elevation is 90 meters above sea level and its slope gradient ranging from 0.5 to 2 percent. The width of the river bed varies in the range of 80 to 120 meters.
Topographic slope in dam reservoir vicinity is variable between 12-25, degree and the slopes more than 25 is rarely observed; they are mainly observed in MT3 unit (Tahtoon formation). Recent sediments are locally observed with 5-10 m height with angle of 90 slope at river margin. All of these sediments will be flooded.
From topographic point of view, there is no deep valley relative to Sarnay River in the studied area.
Rock forming the reservoir area is mainly marl, shale, sandstone of Miocene and Pliocene conglomerate. These sediments are easily weathered and impermeable and layer dips of layers are toward upstream.
|
Catchment |
Area (Km2) |
Average Height (m.a.s.l) |
Average Slope (%) |
Average Slope of the river (%) |
Length of Main River |
|
Sarney Dam |
706 |
702 |
3.94 |
0.5-2% |
90 km |
Meteorology
The aim of the climatological studies in Sarney catchment is to study the rainfall, evaporation and other climatic parameters in order to provide the basic information required for hydrological and other related studies.According to Domarten Climate Classification approach, Brentin (Minab), Takht-e-Minab, Jagdan, Minab dam, Sorkha, Shamju, Faryab and Mazabi stations are classified in the desert region and based on climate Silianinov approach, these stations are classified in dry region.
Due to the lack of meteorological stations with appropriate statistical periods and sufficient numbers within the catchment area, 95 meteorological stations in an appropriate region were selected to study the results of analysis on different parameters and use them for the considered area.
Hydrology
The second phase hydrological study was conducted to review and accurately determine the design parameters of hydraulic structures derived from the first phase studies.The first stage was to elaborate the physiographic parameters based on 1:25,000 maps published by National Mapping Agency. The study parameters were estimated as follows:
Dam catchment area: 7.6 km2
Average slope of dam catchment area: 3.94 %
Average elevation of dam catchment area: 7.2 m
Then, using statistical correction and lengthening (by HEC-4 software) on Kalat-e-Rostam, Garove, Mazabi, Ainma, Jaghin, Rudan, Minab, Brentin, Sarmoqasem and Shamil stations which are the main stations in the area, estimating the direction of the long-term average for each of these dams was determined. In this study, the average annual discharge at the dam site was estimated to be 1.49 cubic meters per second.
In order to estimate sediment using sediment discharge, sedimentation was estimated to be 600 tons per square kilometer per year for Zarani Dam and 500 tons per square kilometer per year for Sarney Dam.
Due to the critical importance of flooding, this report uses the rainfall adjusting method of Behravanab and the formulas of SCS, Clark, and Snyder, and takes advantage of HMS-HEC software for comprehensive studies on flooding in the region that resulted in choosing the SCS method with Minab rainfall pattern as the proper method.
Regional hydrology status shows the torrential rainfall derived from 9 stations (Joomahaleh - Mazabi, etc.).
Flood
Water quality
From dam site point of view, Schuler diagram shows that the studied river water at the inlet to the plain has good quality.Sedimentation
The total sedimentary load of Sarney site is estimated C3S2 thousand tons per year respectively.Planning the water resources
Sarney reservoir dam has been proposed in order to supply the fresh water needs and so much shortage, which exist in the region. This dam is located near to the conveyance installations and consumption of Minab. Therefore, it can supply the fresh water after providing the necessary relief quantity for keeping the balance of downstream underground water (aquifer). Therefore, Sarney reservoir dam is one of recoverable and exploitable water resources to supply some of fresh water need in Bandar Abbas, Minab and Qeshm in the future years. Annual adjustment is 19 Mm3 for drinking and the 9 Mm3 for feeding underground water downstream.Geology
From the view point of Iran geology, the studied area is located at the western border of Mokran structural zone adjacent to southeast of Zagros structural zone, and in the coastal Mokran area. The dominant lithology in the catchment area of the dam mainly consists of shale, sandstone, mudstone, silt stone, and a little Gypsum, covering approximately 85- 90% of the area. These rocks are of low permeability and have no role in rainfalls storage in terms of sedimentation and erosion are at high levels. Red sandstone, conglomerate and crystallized limestone, mainly forming large and small colored blocks, have low permeability. Coarse sediment from erosion of rocks has high permeability but due to their low thickness have no influence on water storage.Seismicity
The dam site is on Sarney River in Mokran Zone of Zagross Mountain Range. The Dam site is located in western side of Mokran structural zone. Seism tectonics studies show that seismic activities have been relatively high in the area around the dam site during the 20th century. The earthquakes sites are located in half northwest part of area around dam site (radius=200 km). Most of historical earthquakes sites are located around Bandar Abbas and Qeshm Island. The most recent earthquake was on 21 July 1965 with a magnitude of Ms5.1, about 13 km distance from the dam site. The field studies shows that in general the surface faulting process is not dominant in the project area site presently. This is evidenced by continuation of outcrop key layers in river bed. The most important linear structures around the dam are two segments of Zendan fault which are at 2.5 and 3.75 km far from the site. Magnitude of the earthquakes around the dam site has been determined using probabilistic method.Dam reservoir
Dam reservoir is located near Baghak and Nahtan villages. According to political divisions Baghak and Nahtan villages belong to Karyan district, central part, Minab Town, Hormozgan Province.