Presentation.pptx.HYDROLOGY AND HYDRAULICS STRUCTURES

HYDRAULICS STRUCTURES AND GROUND WATER IMPROVEMENT

1. DAMS PRESENTED BY: VIDYALOKESH H SOUJANYA P

2. CONTENT INTRODUCTION CLASSIFICATION OF DAM SELECTION OF TYPE OF DAM SITE SELECTION CRITERIA OF DAM

3. INTRODUCTION Dam is the physical obstruction or barrier constructed across the width of river to store water in its upstream. The pool of water is stored on the upstream side of the dam is called Reservoir. India has 5754 number of dams(5334 are constructed and 411 are under construction) India has the 3 rd largest number of dams in the world, following China and the United States. Maharashtra has the large number of dams over 2300 among Indian States

4. Tehri Dam in the state of Uttarakhand. Is the highest dam in India with a height of 260.5 meters Bhakra Nangal Dam in Himachal Pradesh. Is the largest dam in India with a height of 225 meters

5. Hirakud Dam in Odisha. Is the longest dam in India with the length of 25.79 kilometers and also the largest earth dam in India. Nagarjuna Sagar Dam in Telangana. Is the largest masonry dam and also the world largest artificial lake.

6. Sardar Sarovar Dam in Gujarat. Is the largest dam in the Narmada Valley project. Kallanai Dam in Tamil Nadu. Is the oldest dam and also oldest irrigation still used today.

7. Classification of dams Classification based on rigidity Classification based on construction material Classification based on function Classification based on structure and design of dam Classification based on hydraulic design Classification based on gross storage

8. Classification based on Rigidity RIGID DAM A rigid dam is quite stiff. It is made of rigid materials like concrete , masonry ,steel, and wood. NON-RIGID DAM A non rigid dam is less stiff . It is made of rock and earth fill materials.

9. Classification based on construction material 1.CONCRETE DAM Concrete is the most used material to construct a dam. Most of the major dam in the world are built using concrete Gravity dams, Arch dams are constructed using concrete EX: The katse dam, Kerala

10. EARTHFILL DAM Earthen dam are made of ordinary soil which is cheaply available. This type of dams are suitable where the foundation soil is very weak and not strong enough to carry the load of masonry dam. ROCKFILLED DAM Rock fill dam are constructed using rocks It is more stable and earthen dams and its flexible nature helps it better against earthquake force Ex: Tehri dam

11. MASONRY DAM Masonry dams are built using either stone masonry or brick masonry Cement mortar is used join the masonry blocks Gravity dam, Arch dams are example of masonry dam. TIMBER DAM Timber dam is generally used for temporary purpose such as to divert the water for the construction of main dam and to control flood flow

12. STEEL DAM Steel dam are also used for temporary requirement like timber dams. Steel plates and inclines struts are used for the construction of steel dam

13. Classification based on structure and design of dam GRAVITY DAM A Gravity dam is the structure which resist the external forces by its own weight. Gravity dam are generally constructed by masonry or concrete Good foundation is required to construct gravity dam preferable rocky strata Ex: Nagarjuna sagar dam

14. ARCH DAM An arch dam is curved in plan with its convex upstream. Various forces coming onto the dam is resisted by the arch action. The load coming onto the dam are transferred to the abutments. Ex: Idukki dam , kerala

15. BUTTRESS DAM It is the dam that uses a series of the angled supports(buttress) to hold up the dam wall and resist the forces of water Instead of relying on the strength of the thick all like other dams , a buttress dam spreads the water pressure across the buttress. This design uses less materials than other dams Ex: Mettur dam , Tamil nadu

16. Classification based on function STORAGE DAM Storage dam is constructed to store water on the upstream side especially during rainy season Ex: Krs dam DIVERSION DAM Diversion dam which is constructed to divert the flow of water into channel or canal Ex: Ranganadi dam

17. DETENSION DAM The main purpose of dam is to control floods . During flood period ,it stores the water DEBRIS DAM The main purpose of the dam is to collect the debris such as slit, sand,

18. COFFER DAM Coffer dam is a temporary structure which generally acts like diversion dam.Provides the dry area for the construction

19. Classification based on hydraulic design OVERFLOW DAM An overflow dam is one which is designed to carry out surplus discharge over its crest Ex: vanivilas dam NON OVERFLOW DAM A non dam is the one which the top of dam is in higher elevation and water is not permitted over the crest. Ex:konya dam

20. Classification based on storage LOW STORAGE HEAD The dam have height of less than 15 meters They are typically used for small scale purposes Ex: Jal Sanchay dam

21. MEDIUM STORAGE HEAD The dams have height between 15 meters to 30 meters They are used for larger hydroelectric power , flood control . Ex: Tibba Dam

22. HIGH STORAGE HEAD These dams with a height of more than 30 meters. High head dams usually constructed for larger purpose such as water storage , hydroelectric generation. Ex: Hirakud dam

23. Selection of type of dam the following main factors are examined at the stage of selection of dam type: Topography and geological conditions of the proposed dam site: A Concreter dam would be the obvious choice for a narrow stream flowing between high and rocky abutments (i.e., deep gorges). Broad valleys in plains would suggest an embankment dam with a separate spillway.

24. 2. Geology and foundation conditions: Geological and hydro-geological characteristics of the strata, which are to carry the weight of the dam, determine the foundation conditions. Any type of dam can be constructed on solid rock foundations. 3. Availability of suitable materials for the dam: If the construction materials which are to be used in large quantity for the construction of dam are available in sufficient quantity within a reasonable distance from the site, the cost of the dam will be considerably reduced due to saving on transportation of the construction materials.

25. Selection of type of dam the following main factors are examined at the stage of selection of dam type: Topography and geological conditions of the proposed dam site: A Concreter dam would be the obvious choice for a narrow stream flowing between high and rocky abutments (i.e., deep gorges). Broad valleys in plains would suggest an embankment dam with a separate spillway. 2. Geology and foundation conditions: Geological and hydro-geological characteristics of the strata, which are to carry the weight of the dam, determine the foundation conditions. Any type of dam can be constructed on solid rock foundations. 3. Availability of suitable materials for the dam: If the construction materials which are to be used in large quantity for the construction of dam are available in sufficient quantity within a reasonable distance from the site, the cost of the dam will be considerably reduced due to saving on transportation of the construction materials.

26. 4. The feasibility of spillway construction:- Spillway requirements are decided by the runoff and stream-flow characteristics. For large spillways, it may be desirable to combine the spillway and dam into one structure. SPILLWAY THE LARGEST DAM SPILLWAY

27. 5. Earthquake zone: If dam is located in earthquake zone, its design must include the earthquake forces. Dam caused by earthquake Concrete gravity dam Rockfill dam Embankment dam

28. 6. Height of Dam: Earthen dams are usually not provided for height more than 30 meter. Hence for greater height, gravity dams are generally preferred. EARTHEN DA M GRAVITY DA M 7. Other consideration: it includes life of dam, the width of roadway to be provided over the dam, overall cost of the construction and maintenance.

29. 4. The feasibility of spillway construction:- Spillway requirements are decided by the runoff and stream-flow characteristics. For large spillways, it may be desirable to combine the spillway and dam into one structure. 5. Earthquake zone: If dam is located in earthquake zone, its design must include the earthquake forces. 6. Height of Dam: Earthen dams are usually not provided for height more than 30 meter. Hence for greater height, gravity dams are generally preferred. 7. Other consideration: it includes life of dam, the width of roadway to be provided over the dam, overall cost of the construction and maintenance.

30. Site Selection Criteria for Dam: Suitable foundation must be available. For economy, the length of the dam should be as small as possible and for given height it should store maximum amount of water. A suitable site for the spillway should be available in or nearby vicinity. The bed level at the dam site should preferably be higher than that of the river basin. This will reduce the height of the dam and will facilitate the drainage problem. The reservoir basin should be reasonably water-tight. Material required for the construction of the dam should be easily available locally. The value of the land and property submerged by the proposed dam should be as low as possible. The dam site should be easily accessible, such that it can be economically connected to important towns. Site for establishing labour colonies and healthy environment should be available near by vicinity.