2 sheets of plastic or tar in the way of a plastic core that is used to seal the plastic polyethyle

Due to the growing demand for water and the lack of access to sources of supply, it seems necessary to maintain and use of groundwater resources, which are suitable in areas with underground water, and ground construction of a dam can be one of the options is desirable.
History of underground dam in the world goes back to ancient hk public holiday 2013 civilizations. hk public holiday 2013 For example, hk public holiday 2013 underground dams on the island Sardyna the Romans built during the Safavid dynasty in Iran for water increase in Mymh Vzvran Madrchah fields of water were diverted to other aqueducts. But now underground dams due to the benefits of the dams are almost level in most regions of the world are used. The design of underground dams in general can be found in four sections: (1) water supply and water resources management -2 (such as blocking or subterranean springs and guide them to springs of the water of the well fields or mother) 3. Prevent Level of groundwater hk public holiday 2013 from saltwater beaches and salt plains like playing -4 environmental hk public holiday 2013 pollution or nuclear radiation and their effects on groundwater. Among the advantages of underground dam to dam level is as follows:
1. Positioning: The first step is to locate underground dams and underground dams due to the possibility of establishing a point of not so according to the characteristics and climate of the region should be considered the best place to build. Area of climate should have the following qualifications:
- With regard to the underground dam with minimum cost, maximum volume and have less leakage, usually with a height of 3 to 4 meters and where the slope of the land is made less than 5% of the property more In a narrow valley or river and found to be consistent.
In cases where natural conditions suitable for underground acts like a barrier and barrier properties due to natural barriers (such as lump impermeable hk public holiday 2013 layer substrate) can play a significant role in positioning and cost have.
In addition to the salt content of the soil and the amount of annual rainfall also examined Bgyrd.vjvd layers of salt causes salt water is stored. However, hk public holiday 2013 recent research has shown that the current slowdown in Adelaide Australia freshwater mixing it with saline groundwater hk public holiday 2013 limit.
- Construction of the dam, the dam first hole drilled perpendicular to the river bed due to shallow Z hkshyya operations done by manpower. Dry alluvial sand and sandy areas with low adhesion properties due to slope instability and possible hk public holiday 2013 collapse of the wall there and dig trenches with alluvial sand makes it difficult, however, because the desired barrier for the location of ground- water- They are easily seen, however, hold down the pumping water level.
- Materials used in the construction of dams in the region, according to three parameters: 1. 2. Borrow consumer spending 3S hvlt do is determine how many of the materials used for the construction of and only the wall of the need levee Dam is. The following are two examples hk public holiday 2013 of materials used in the construction of dams include:
1. compacted hk public holiday 2013 clay: the clay, the conventional method that does not require skilled manpower. Clay layer with a thickness of less cluttered and then compressed. Due to water flow under Ter straw clay surface erosion is likely therefore to protect the walls of plastic sheeting used. Filling the trench by means of appropriate augmentative and moisture out. If underground water supply in the dry season to reduce the possibility of leaks and cracks hk public holiday 2013 in the dam and there is, therefore, with thick walls constructed for maintenance of moisture in the core area, even in the dry periods it possible to be prevented prolong.
2 sheets of plastic or tar in the way of a plastic core that is used to seal the plastic polyethylene is usually far as cost is concerned .km material is the most economical method. When this method is used. It should be noted that materials such as mud provinces have lined up on both sides of the sheet used to prevent cavities by sharp rocks. The protective effects of thermal expansion and contraction changes must be considered.
3. Extraction hk public holiday 2013 of water: Water extraction hk public holiday 2013 is done by either hk public holiday 2013 gravity wells. If the operation of the dam and downstream regions of the topography is also possible to extract the water from the reservoir is gravity.
Underground construction of dams in the period 1370 to provide drinking water is a town in Kerman KAHNOUJ time was done by the Ministry of Construction Jihad dam with a height hk public holiday 2013 of 12 meters and a width of 40 m and a slope of 4% clay core was built with The storage volume hk public holiday 2013 was 1,000 cubic meters.
Conclusion: underground dams due to low cost, ease of construction, water supply, sanitation, and offers many advantages over the surface of the dam, including arid and semi-arid climate with regard to Iran would be an affordable and simple method for the use of groundwater.
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