- What are dams?
- Types of dams
- Classification Based on the Flow over its Top.
- Classification Based on the Use of the Dam.
- What are the advantages of dams?
- What are the disadvantages of dams?
- Uses of dams
- Construction of dams
- How dams generate electricity
- The impact of the construction of dams
- How do dams affect the environment?
- List of dams in India
- Questions and Answers related to Dams
What are dams?
A Dam can be defined as an obstruction or a barrier built across a stream or a river. At the back of this barrier, the water gets collected and the side on which water is called the upstream side, and the other side is called the downstream side. The water collected and formed upstream is called the reservoir.
Types of dams
There are 7 types of dams as follows.
1. Earth fill dams
- Earth fill dams are made by solidifying the soil down slowly.
- These are constructed at places that are not strong enough to bear the weight of a concrete dam
- Mainly used in places where the earth is more easily available as a building material compared to others.
2. Rockfill dams
- These dams are constructed using loose rocks and boulders piled in the riverbed
- On the upstream side of the dam, a slab of reinforced concrete is often laid across to make it watertight
3. Solid Masonry Gravity dams
- These are big and expensive dams but are more durable and solid than earth and rock dams
- These are of great weight so that can be built at places where there is a natural strong foundation.
4. The hollow masonry gravity dams
- Build in the same way as solid masonry gravity dams but with less concrete or masonry
- A deck of RCC or arches carry the weight of water
- These are difficult to build and are only adopted if skilled labor is easily available.
5. Steel dams
- Not used for major works
- Used as temporary cofferdams needed for constructing permanent dams
- Timber is used for the reinforcement of steel cofferdams.
6. Timber dams
- Timber dams have short-lived around 30 to 40 years with proper maintenance
- Mostly used in agricultural areas to create a pool of water for cattle and to meet other low-level needs.
7. Arch dams
- These are dams in arch shape which are very complex and complicated
- The horizontal arch action of the dam is used to hold back the water
- Best suited at sites where dams must be extremely high and narrow.
Classification Based on the Flow over its Top.
(i) Overflow dams
- These dams are designed in such a way to pass the surplus water over their crest
- Mostly called Spillways
- Must be constructed with materials that will not be eroded by such discharges.
(ii) Non-overflow dams
- Designed not to be overtopped
- Gives a wider choice of materials including earth fill and rockfill
- In most cases, the overflow and non-overflow dams are combined to form a composite single structure.
Classification Based on the Use of the Dam.
(i) Storage dam
- Constructed to store water during the time of surplus water and to be used later in the time of shortage
- They can be further classified according to the use of water like navigation, recreation, water supply, fish, electricity, etc.
(ii) Diversion dam
- Small dams are used to raise the water level to off-take canal or some other conveyance system
- Useful for irrigation development works
- Mostly called a weir or a barrage.
(iii) Detention dam
- These dams detain floodwaters temporarily to flood runoff
- To minimize bad effects caused due to flood
- Also constructed to trap sediments and often called Debris dams.
What are the advantages of dams?
- Water can be stored and also used for irrigation using dams
- Water can be distributed to the nearest places for drinking purposes
- Water stored in dams can be used for generating electricity
- During floods, dams can be used for storing or diverting water
- Dams also provide recreational areas like boating, parks, etc.
What are the disadvantages of dams?
- When making dams much biodiversity near the dams are affected
- A huge amount of money is needed for construction as well as for the maintenance of the dams
- Many inhabitants near the dam construction are displaced without any compensation.
Uses of dams
- Water stored in dams can be used for recreation or as the reservoir of drinking water
- Can be used for irrigation purposes
- The energy of the water collected can be used to turn a mill to grind wheat or to turn blades of a turbine to generate electricity
- In times of floods, dams can be used as protection of towns and cities nearby.
Construction of dams
The typical steps in the construction of a dam are
- Diverting the river:- when constructing dams across a river it is difficult and expensive to construct a separate channel for diverting the river so a dry construction pit is formed on one side leaving the other side open for water flow and after construction is finished on one side the next side is done in a similar way
- Preparing the foundation of the dam:- The foundation must be strong and should be constructed on the strong ground so that it can carry the weight of the dam as well as the weight of the water collected
- Building the dam:- According to the place and use of the dam the required type of dam is constructed
- Filling the reservoir
- Testing all the components like valves, and floodgates of the dam
- Monitoring the working of the newly constructed dam
- Constantly maintenance is done accordingly.
How dams generate electricity
- A flowing river releases potential energy in the form of kinetic energy. Dams act as a barrier and halt this kinetic energy by storing a river’s potential energy in a reservoir. The hydraulic head, created by the depth of water and water’s velocity as it travels through the dam’s penstock, enables the turbine in the hydroelectric plant to spin.
- A taller dam produces more hydraulic heads and can spin larger turbines. The turbine spins and the hydraulic head is converted into kinetic energy.
- The rotational motion of the turbine generates electrical energy. The turbines are coupled with electrical generators either directly or via a gearbox. The commutator and brush assembly capture the flow of electricity, which is created by the generator spinning armature relative to its stator
- The generated electricity is transformed quickly into grid-level voltages which then are transmitted via power lines.
The impact of the construction of dams
- The construction of dams has both positive as well as negative effects of=n different factors like humans, the environment, aquatic life, etc.
- Some of the positive impacts of dams are power generation, flood control, economic growth, etc.
- Some of the negative impacts are the loss of biodiversity, relocation of people, change in water quality, and change in direction of flow of the river
How do dams affect the environment?
- Normal passing ways of territorial animals are affected
- The fish can be damaged while passing through the floodgates, turbines, and pumps of high bodied dams
- The temperature of the water, salt, and oxygen distribution may change vertically as a consequence of the reservoir format
- The reproduction of migrating fishes is affected by floods that harm the egg beds.
List of dams in India
Some of the major dams in India are given below:
|S. No||Name of Dam||River||State|
|1||Narayanpur Dam||Krishna River||Karnataka|
|2||Kolkewadi Dam||Vashishti River||Maharashtra|
|3||Harangi Dam||Harangi River||Karnataka|
|4||Mula Dam||Mula river||Maharashtra|
|5||Krishna Raja Sagara Dam||Kaveri River||Karnataka|
|6||Panshet Dam||Ambi River||Maharashtra|
|7||Supa Dam||Kalinadi or Kali river||Karnataka|
|8||Tansa Dam||Tansa river||Maharashtra|
|9||Alamatti Dam||Krishna River||Karnataka|
|10||Wilson Dam||Pravara River||Maharashtra|
|11||Kadra Dam||Kalinadi River||Karnataka|
|12||Bhatsa Dam||Bhatsa river||Maharashtra|
|13||Linganamakki dam||Sharavathi River||Karnataka|
|14||Jayakwadi Dam||Godavari River||Maharashtra|
|15||Tunga Bhadra Dam||Tungabhadra River||Karnataka|
|16||Koyna Dam||Koyna River||Maharashtra|
|17||Panchet Dam||Damodar River||Jharkhand|
|18||Mulshi Dam||Mula River||Maharashtra|
|19||Chandil Dam||Swarnarekha River||Jharkhand|
|20||Pawna Dam||Maval River||Maharashtra|
|21||Dhauli Ganga Dam||Dhauli Ganga River||Uttarakhand|
|22||Maithon Dam||Barakar River||Jharkhand|
|23||Ujani Dam||Bhima River||Maharashtra|
|24||Tehri Dam||Bhagirathi River||Uttarakhand|
|25||Uri Hydroelectric Dam||Jhelum River||Jammu and Kashmir|
|26||Yeldari Dam||Purna river||Maharashtra|
|27||Rihand dam||Rihand River||Uttar Pradesh|
|28||Dumkhar Hydroelectric Dam||Indus River||Jammu and Kashmir|
|29||Gandhi Sagar Dam||Chambal River||Madhya Pradesh|
|30||Mettur Dam||Kaveri River||Tamil Nadu|
|31||Baglihar Dam||Chenab River||Jammu and Kashmir|
|32||Bansagar Dam||Sone River||Madhya Pradesh|
|33||Perunchani Dam||Paralayar River||Tamil Nadu|
|34||Chamera Dam||Ravi River||Himachal Pradesh|
|35||Bargi Dam||Narmada River||Madhya Pradesh|
|36||Vaigai Dam||Vaigai River||Tamil Nadu|
|37||Nathpa Jhakri Dam||Satluj River||Himachal Pradesh|
|38||Barna Dam||Barna River||Madhya Pradesh|
|39||Hirakud Dam||Mahanadi River||Odisha|
|40||Bhakra Nangal Dam||Sutlej River||Himachal Pradesh and Punjab Border|
|41||Rajghat Dam||Betwa River||Uttar Pradesh and Madhya Pradesh Border|
|42||Indravati Dam||Indravati River||Odisha|
|43||Pandoh Dam||Beas River||Himachal Pradesh|
|44||Neyyar Dam||Neyyar River||Kerala|
|45||Jalaput Dam||Machkund River||Andhra Pradesh and Odisha Border|
|46||Dantiwada Dam||Banas River||Gujarat|
|47||Mullaperiyar Dam||Periyar River||Kerala|
|48||Gangapur Dam||Godavari river||Maharashtra|
|49||Kadana dam||Mahi River||Gujarat|
|50||Walayar Dam||Walayar River||Kerala|
|51||Khadakwasla Dam||Mutha River||Maharashtra|
|52||Dharoi Dam||Sabarmati River||Gujarat|
|53||Parambikulam Dam||Parambikulam River||Kerala|
|54||Upper Manair Dam||Manair River and Kudlair River||Telangana|
|55||Ukai Dam||Tapti River||Gujarat|
|56||Kundala Dam||Kundala Lake||Kerala|
|57||Mid Manair Dam||Manair River and SRSP Flood Flow Canal||Telangana|
|58||Singur dam||Manjira River||Telangana|
|59||Idukki Dam||Periyar River||Kerala|
|60||Lower Manair Dam||Manair River||Telangana|
|61||Srisailam Dam||Krishna River||Andhra Pradesh|
|62||Peechi Dam||Manali River||Kerala|
|63||Radhanagari Dam||Bhogawati River||Telangana|
|64||Somasila Dam||Pennar River||Andhra Pradesh|
|65||Malampuzha Dam||Malampuzha River||Kerala|
|66||Vaitarna Dam||Vaitarna river||Maharashtra|
|67||Nizam Sagar Dam||Manjira River||Telangana|
|68||Kodasalli Dam||Kali River||Karnataka|
|69||Girna Dam||Girana river||Maharashtra|
How many dams are in Kerala and their names?
There are 57 major dams in Kerala, please see the list with their district and river name.
|S. No||Name of Dam||District||River|
|1||Peruvaripallam Dam||Palakkad||Peruvaripallam River|
|2||Thunakkadavu Dam||Palakkad||Thunakadavu River|
|4||Munnar Headworks Dam||Idukki||Muthirapuzha River|
|5||Pambla Dam||Idukki||Periyar River|
|6||Kallarkutty Dam||Idukki||Muthirappuzha River|
|7||Idamalayar Dam||Ernakulam||Periyar River|
|8||Veluthodu Dam||Pathanamthitta||Pamba River|
|9||Anathode Dam||Pathanamthitta||Pamba River|
|10||Kochupamba Dam||Pathanamthitta||Pamba River|
|14||Moozhiyar Dam||Pathanamthitta||Pamba River|
|15||Maniyar Dam||Pathanamthitta||Kakkattar River|
|16||Asurankund Dam||Thrissur||Chelakkara River|
|17||Kakkayam Dam||Kozhikode||Kuttiyadi River|
|18||Erattayar Dam||Idukki||Erattayar Lake|
|19||Kulamavu Dam||Idukki||Periyar River|
|20||Cheruthoni Dam||Idukki||Periyar River|
|21||Mullaperiyar Dam||Idukki||Periyar River|
|22||Karapuzha Dam||Wayanad||Karapuzha River|
|23||Banasura Sagar Dam||Wayanad||Kabini River|
|24||Chimmony Dam||Thrissur||Kurumali River|
|25||Malankara Dam||Idukki||Muvattupuzha River|
|26||Peppara Dam||Thiruvananthapuram||Karamana River|
|27||Pazhassi Dam||Kannur||Valapattanam River|
|28||Periyar Lake||Idukki||Periyar River|
|29||Bhoothathankettu Dam||Ernakulam||Periyar River|
|30||Neriamangalam Dam||Ernakulam||Periyar River|
|31||Sengulam Dam||Idukki||Periyar River|
|32||Mattupatti Dam||Idukki||Periyar River|
|33||Kundala Dam||Idukki||Periyar River|
|34||Anayirankal Dam||Idukki||Periyar River|
|35||Ponmudi Dam||Idukki||Periyar River|
|36||Idukki Dam||Idukki||Periyar River|
|38||Pamba Dam||Pathanamthitta||Pamba River|
|39||Kuttiady Dam||Kozhikode||Kuttiady River|
|40||Neyyar Dam||Thiruvananthapuram||Neyyar River|
|41||Vazhani Dam||Thrissur||Keecheri River|
|42||Peechi Dam||Thrissur||Karuvanoor River|
|43||Aruvikkara Dam||Thiruvananthapuram||Karamana River|
|44||Thenmala Dam||Kollam||Kallada River|
|45||Peringalkuthu Dam||Thrissur||Chalakkudy River|
|46||Sholayar Dam||Thrissur||Chalakkudy River|
|47||Peruvaaripallam Dam||Palakkad||Chalakkudy River|
|48||Thunakkadavu Dam||Palakkad||Chalakkudy River|
|49||Parambikulam Dam||Palakkad||Chalakkudy River|
|50||Kanjhirapuzha baby Dam||Palakkad||Bharathapuzha River|
|51||Kanjirapuzha Dam||Palakkad||Bharathapuzha River|
|52||Siruvani Dam||Palakkad||Siruvani River|
|53||Walayar Dam||Palakkad||Bharathapuzha River|
|54||Pothundi Dam||Palakkad||Bharathapuzha River|
|55||Chulliar Dam||Palakkad||Bharathapuzha River|
|56||Meenkara Dam||Palakkad||Bharathapuzha River|
|57||Mangalam Dam||Palakkad||Bharathapuzha River|
|58||Malampuzha Dam||Palakkad||Bharathapuzha River|
Why dams are called multipurpose projects?
Because dams are not just constructed for irrigation but also electricity generation, water supply, flood control, creation, inland navigation, and fish breeding. Since dams are used for multiple purposes they are called multipurpose projects.
How many dams are in the world?
There are around 60,000 large dams worldwide with more than 3,700 currently planned or under construction
How many dams are in Gujarat?
There are 204 dams in Gujarat.
How many dams are in the Periyar River?
There are 14 dams in the Periyar river namely
1. Idukki Dam
2. Ponmudi Dam
3. Anayirankal Dam
4. Kundala Dam
5. Mattupatti Dam
6. Sengulam Dam
7. Neriamangalam Dam
8. Bhoothathankettu Dam
9. Periyar Lake
10. Mullaperiyar Dam
11. Cheruthoni Dam
12. Kulamavu Dam
13. Idamalayar Dam
14. Pambla Dam.
What are embankment dams?
An embankment dam is a large artificial dam created by the placement of compaction of a complex semi-plastic mound of various compositions of rock or soil.
How do dams prevent flooding?
During the flood, dams impound floodwater and then either release them under control to the river below the dam or store or divert the water for other uses.