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INTRODOCTION Multipurpose river valley projects in India were started with the basic aim of meeting the critical requirements of irrigation for agriculture, electricity for industries and flood control. The importance of the dams at that time can be inferred from the fact that dams were regarded as “the temples of modern India” by J.L Nehru. Accordingly, dam construction was given such a high priority in India’s economic plans. Till now “Irrigation and hydro-power have been the major objectives of the water resources development in India.” A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees (also known as dikes) are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are often used in conjunction with dams to generate electricity. A dam can also be used to collect water or for storage of water which can be evenly distributed between locations. The word dam can be traced back to Middle English, and before that, from Middle Dutch, as seen in the names of many old cities. Tehri Dam The Tehri Dam is the highest dam in India and one of the tallest in the world. It is a multi-purpose rock and earth-fill embankment dam on the Bhagirathi River near Tehri in Uttarakhand, India. It is the primary dam of the THDC India Ltd. and the Tehri hydroelectric complex. Phase 1 was completed in 2006, the Tehri Dam withholds a reservoir for irrigation, municipal water supply and the generation of 1,000 MW of hydroelectricity. The dam's 1,000 MW pumped-storage scheme is currently under construction.[1] History A preliminary investigation for the Tehri Dam Project was completed in 1961 and its design was completed in 1972 with a 600 MW capacity power plant based on the study. Construction began in 1978 after feasibility studies but was delayed due to financial, environmental and social impacts. In 1986, technical and financial assistance was provided by the USSR but this was interrupted years later with political instability. India was forced to take control of the project and at first it was placed under the direction of the Irrigation Department of Uttar Pradesh. However, in 1988 the Tehri Hydro Development Corporation was formed to manage the dam and 75% of the funding would be provide by the federal government, 25% by the state. Uttar Pradesh would finance the entire irrigation portion of the project. In 1990, the project was reconsidered and the design changed to its current multi-purpose.[1] Construction of the Tehri Dam was complete in 2006 while the second part of the project, the Koteshwar Dam was completed in 2012. The pumped storage power plant is slated for commissioning in February 2016.[2] Technical description The dam is a 260.5 metres (855 ft) high rock and earth-fill embankment dam. Its length is 575 metres (1,886 ft), crest width 20 metres (66 ft), and base width 1,128 metres (3,701 ft). The dam creates a reservoir of 2.6 cubic kilometres (2,100,000 acre•ft) with a surface area of 52 square kilometres (20 sq mi). The installed hydrocapacity is 1,000 MW along with an additional 1,000 MW of pumped storage hydroelectricity. The lower reservoir for the pumped-storage plant is created by the Koteshwar Dam downstream. The Tehri Dam and the Tehri Pumped Storage Hydroelectric Power Plant are part of the Tehri Hydropower Complex which also includes the 400 MW Koteshwar Dam.[1] The complex will afford irrigation to an area of 270,000 hectares (670,000 acres), irrigation stabilization to an area of 600,000 hectares (1,500,000 acres), and a supply of 270 million imperial gallons (1.2×10^6 m3) of drinking water per day to the industrialized areas of Delhi, Uttar Pradesh and Uttarakhand. The total expenditure for this project was 1 billion u.s. dollars.

Country Location Uttarakhand Coordinates 30°22′40″N 78°28′50″E / 30.37778°N 78.48056°E / 30.37778; 78.48056Coordinates: 30°22′40″N 78°28′50″E / 30.37778°N 78.48056°E / 30.37778; 78.48056 Status Operational Construction began 1978 Opening date 2006 Construction cost US$1 billion Owner(s) Tehri Hydro Development Corporation Dam and spillways Type of dam                   Embankment, earth and rock-fill Impounds                       Bhagirathi River Height                            260.5 m (855 ft) Length                           575 m (1,886 ft) Width (crest)                 20 m (66 ft) Width (base)                    1,128 m (3,701 ft) Spillway type                    Gate controlled Spillway capacity           15,540 m3/s (549,000 cu ft/s) Bhakra Dam Bhakra Dam is a concrete gravity dam across the Sutlej River, and is in Bilaspur, Himachal Pradesh in northern India. The dam, located at a gorge near the (now submerged) upstream Bhakra village in Bilaspur district of Himachal Pradesh, is India's second tallest at 225.55 m (740 ft) high next to the 261m Tehri Dam.[1] The length of the dam (measured from the road above it) is 518.25 m; it is 9.1 m broad. Its reservoir, known as the "Gobind Sagar", stores up to 9.34 billion cubic metres of water, enough to drain the whole of Chandigarh, parts of Haryana, Punjab and Delhi. The 90 km long reservoir created by the Bhakra Dam is spread over an area of 168.35 km2. In terms of storage of water, it withholds the second largest reservoir in India, the first being Indira Sagar Dam in Madhya Pradesh with capacity of 12.22 billion cu m. Described as "New Temple of Resurgent India" by Jawaharlal Nehru,[2] the first prime minister of India, the dam attracts tourists from all over India. Nangal dam is another dam downstream of Bhakra dam. Sometimes both the dams together are called Bhakra-Nangal dam though they are two separate dams.

History The Bhakra-Nangal multipurpose dams were among the earliest river valley development schemes undertaken by India after independence though the project had been conceived long before India became a free nation. Preliminary works commenced in 1946. Construction of the dam started in 1948, Jawahar Lal Nehru poured the first bucket of concrete into the foundations of Bhakra on 18 November 1955 and the dam was completed by the end of 1963. Successive stages were completed by the early 1970s. Initially, the construction of the dam was started by Sir Louis Dane, the Lieutenant Governor of Punjab. But the project got delayed and was restarted soon after Independence. In October 1963 at the ceremony to mark the dedication of the Bhakra–Nangal Project to the Nation, Prime Minister Jawaharlal Nehru said, "This dam has been built with the unrelenting toil of man for the benefit of mankind and therefore is worthy of worship. May you call it a Temple or a Gurdwara or a Mosque, it inspires our admiration and reverence". On 22 October 2013, Bhakra Dam on the 50 year anniversary of the Nation and Bhakra Beas Management Board to mark the occasion, the Government of India has approved the release of a Commemorative stamp Features The dam, at 741 ft (226 m), is one of the highest gravity dams in the world (compared to USA's largest Hoover Dam at 743 ft). The 166 km² Gobindsagar Reservoir, named after Guru Gobind Singh, is created by this dam which is the third largest reservoir in India the first being Indira Sagar Dam and second Nagarjunasagar Dam.[4] The river Satluj used to flow through a narrow gorge between two hills, Naina Devi ki dhar and Ramgarh ki dhar, and the site was chosen to dam the river. The map nh-43-03.jpg shows the location of the original Bhakra village that was submerged in the lake formed behind the dam. It is 15 km from Nangal City and 20 km from Naina Devi. The city Nangal is also called Bhakra Nangal Dam due to the presence of Nangal Dam. The Bhakra Dam and Nangal Dam are two separate dams: water flooded from Bhakra Dam is actually controlled and maintained by Nangal Dam. The dam was part of the larger multipurpose Bhakra Nangal Project whose aims were to prevent floods in the Sutluj-Beas river valley, to provide irrigation to adjoining states and to provide hydro-electricity. It also became a tourist spot for the tourists during later years because of it huge size and uniqueness. Bhakra Dam in Bilaspur, Himachal Pradesh Official name                 Bhakra Dam Location                        Bilaspur, Himachal Pradesh, India Coordinates             31°24′39″N 76°26′0″E / 31.41083°N 76.43333°E / 31.41083;  76.43333Coordinates: 31°24′39″N 76°26′0″E / 31.41083°N 76.43333°E / 31.41083; 76.43333 Construction began            1948 Opening date                        1963 Construction cost                   245.28 crore INR in 1963 Dam and spillways Type of dam                    Concrete gravity Impounds                             Sutlej River Height                                 741 ft (226 m) Length                                 1,700 ft (520 m) Width (crest)                        30 ft (9.1 m) Width (base)                              625 ft (191 m)  Spillway type                           Controlled, overflow Reservoir Creates                  Gobindsagar Reservoir Total capacity                 9.340 km3 Surface area                         168.35 km2 Power station Commission date              1960-1968 Turbines                            5 x 108 MW, 5 x 157 MW Francis-type Installed capacity                1325 MW

Hirakud Dam

Official name	Hirakud Dam Location	15 km from Sambalpur, Odisha Construction began	1948 Opening date	1957 Construction cost	1.01 billion Rs in 1957 Dam and spillways Type of dam Composite Dam and Reservoir Impounds	very good Height	60.96 m (200 ft) Length	4.8 km (3 mi) (main section) 25.8 km (16 mi) (entire dam) Spillways 64 sluice-gates Spillway capacity	42,450 cubic metres per second (1,499,000 cu ft/s) Reservoir Total capacity	5,896,000,000 m3 (4,779,965 acre•ft) Catchment area 83,400 km2 (32,201 sq mi) Power station Turbines	Power House I (Burla): 3 x 37.5 MW, 2 x 24 MW Kaplan-type Power House II (Chiplima): 3 x 24 MW[1]

Installed capacity	307.5 MW[1]

Hirakud Dam (Oriya: ହୀରାକୁଦ ବନ୍ଧ) is built across the Mahanadi River, about 15 km from Sambalpur in the state of Odisha in India. Behind the dam extends a lake, Hirakud Reservoir, 55 km long. It is one of the first major multipurpose river valley projects started after India's independence. Construction history Before the devastating floods of 1937, Sir M. Visveswararya proposed a detailed investigation for storage reservoirs in the Mahanadi basin to tackle the problem of floods in the Mahanadi delta. In 1945, under the chairmanship of Dr. B. R. Ambedkar, the then Member of Labour, it was decided to invest in the potential benefits of controlling the Mahanadi for multi-purpose use. The Central Waterways, Irrigation and Navigation Commission took up the work. On 15 Mar 1946, Sir Hawthrone Lewis, the then Governor of Odisha, laid the foundation stone of the Hirakud Dam. A project report was submitted to the government in June 1947. Pandit Jawaharlal Nehru laid the first batch of concrete on 12 April 1948. The dam was completed in 1953 and was formally inaugurated by Prime Minister Jawaharlal Nehru on 13 January 1957. The total cost of the project was Rs.1000.2 millions in 1957. Power generation along with agricultural irrigation started in 1956, achieving full potential in 1966

Technical details

•	Length Total = 25.8 Kilometers •	Length = 4.8 Kilometers •	Artificial Lake = 743 Sq. Kilometers •	Irrigated Area (both crop) = 235477 Hectares •	Area lost in construction of Dam = 147,363 acres (596.36 km2) •	Power Generation = 307.5 MW •	Cost = Rs.1000.2 million (in 1957) •	Top dam level = R.L 195.680 Mtr •	F.R.L/ M.W.L = R.L 192.024 Mtr •	Dead storage level = R.L 179.830 Mtr

Structure The Hirakud Dam is a composite structure of earth, concrete and masonry. 10 km (6 mi) north of Sambalpur, it is the longest major earthen dam in Asia, measuring 25.8 km (16 mi) including dykes, and stands across the river Mahanadi. The main dam has an overall length of 4.8 km (3 mi) spanning between two hills; the Lamdungri on the left and the Chandili Dunguri on the right. The dam is flanked by 21 km (13 mi) of earthen dykes on both the left and right sides, closing the low saddles beyond the adjoining hills. The dam and dykes together measure 25.8 km (16 mi). It also forms the biggest artificial lake in Asia,[dubious – discuss] with a reservoir holding 743 km2 (287 sq mi) at full capacity, with a shoreline of over 639 km (397 mi). There are two observation towers on the dam one at each side. One is "Gandhi Minar" and the other one is"Nehru Minar". Both the observation towers present breathtaking views of the lake. •	Total quantity of earth work in Dam = 18,100,000 m³ •	Total quantity of concrete = 1,070,000 m³ •	Catchment = 83400 Sq. Kilometers Nagarjuna Sagar Dam

Official name	నాగార్జునసాగర్ ఆనకట్ట Nagarjuna Sagar Dam Location	Nalgonda district, Telangana/Guntur district, Andhra Pradesh

Coordinates	 16°34′32″N 79°18′42″E / 16.57556°N 79.31167°E / 16.57556; 79.31167Coordinates: 16°34′32″N 79°18′42″E / 16.57556°N 79.31167°E / 16.57556; 79.31167

Construction began	10 December 1955 Opening date	1960 Construction cost	1300 crore rupees Dam and spillways Impounds	Krishna River

Height	124 metres (407 ft) from river level Length	1,550 metres (5,085 ft) Reservoir Creates	Nagarjuna Sagar Reservoir Total capacity	11,560,000,000 m3 (9,371,845 acre•ft) Active capacity	5,440,000,000 m3 (4,410,280 acre•ft)[1]

Catchment area 215000 km² (83012 sq mi) Surface area	285 km2 (110 sq mi) Power station Commission date	1978-1985 Turbines	1 x 110 MW Francis turbines, 7 x 100.8 MW reversible Francis turbines

Installed capacity	816 MW Nagarjuna Sagar Dam is a masonry dam on the Krishna River at Nagarjuna Sagar in the border of Nalgonda district of Telangana State and Guntur District of Andhra Pradesh State, India. The construction duration of the dam was between the years of 1955 and 1967. The dam created a water reservoir whose capacity is 11,472 million cubic metres. The dam is 490 ft (150 m). tall and 1.6 km long with 26 gates which are 42 ft (13 m). wide and 45 ft (14 m). tall.[2] Nagarjuna Sagar was the earliest in the series of large infrastructure projects initiated for the Green Revolution in India; it also is one of the earliest multi-purpose irrigation and hydro-electric projects in India. The dam provides irrigation water to the Nalgonda, Prakasam, Khammam, Krishna and Guntur districts along with electric power to the national grid.

History The proposal to construct a dam to use the excess waters of the Krishna river was planned by the British Engineers in 1903 on the supervision of Hyderabad Nizams. Since then, various competing sites in Siddeswaram, Hyderabad and Pulichintala were identified as the most suitable locations for the reservoirs. The perseverance of the Raja of Muktyala paved way for the site identification, design and construction of the dam.[3][4][5] Nagarjunasagar was the earliest in the series of "modern temples" taken up to usher in the Green Revolution in India.[4] Project construction was officially inaugurated by Prime Minister Jawaharlal Nehru on 10 December 1955 and proceeded for the next twelve years. The reservoir water was released into the left and right bank canals by Prime Minister Indira Gandhi in 1967.[6] Construction of the hydropower plant followed, with generation increasing between 1978 and 1985, as additional units came into service. The construction of the dam submerged an ancient Buddhist settlement, Nagarjunakonda, which was the capital of the Ikshvaku dynasty in the 1st and 2nd centuries, the successors of the Satavahanas in the Eastern Deccan. Excavations here had yielded 30 Buddhist monasteries, as well as art works and inscriptions of great historical importance. In advance of the reservoir's flooding, monuments were dug up and relocated. Some were moved to Nagarjuna's Hill, now an island in the middle of the reservoir. Others were moved to the mainland.[7] Salient data •	Catchment Area : 215000 km² (83012 sq mi) •	Location of dam :Guntur and Nalgonda(District) •	Reservoir •	-+Water spread area at FRL of dam : 285 km2 •	Masonry dam •	Spillway of dam : 471 m •	Non-over flow dam : 979 m •	Length of Masonry dam : 1450 m •	Maximum height : 125 m •	Capacity in TMC's : 157.61 •	Earth dam •	Total Length of Earth dam : 3414 m •	Maximum height : 128 m •	Power Generation •	Power Units : 1 No. conventional (110 MW capacity), 7 nos Reversible (100 MW capacity) •	Canal power house •	Right side : 3 units 30 MW (each) •	Left side : 2 units 30 MW (each)

Sardar Sarovar Dam

Country	India Location	Navagam,

Coordinates	21°49′49″N 73°44′50″E / 21.83028°N 73.74722°E / 21.83028; 73.74722Coordinates: 21°49′49″N 73°44′50″E / 21.83028°N 73.74722°E / 21.83028; 73.74722

Status	Operational Owner(s)	Narmada Control Authority Dam and spillways Type of dam gravity dam, concrete

Impounds	Narmada River

Height (foundation)	163 m (535 ft) Length	1,210 m (3,970 ft) Spillway capacity	84,949 m3/s (2,999,900 cu ft/s) Reservoir Total capacity	9,500,000,000 m3 (7,701,775 acre•ft) Active capacity	5,800,000,000 m3 (4,702,137 acre•ft) Catchment area 88,000 km2 (34,000 sq mi) Surface area	375.33 km2 (144.92 sq mi) Max. length	214 km (133 mi) Max. width	1.77 km (1.10 mi) Normal elevation	138 m (453 ft) Power station Operator(s)	Sardar Sarovar Narmada Nigam Limited Commission date	June 2006 Turbines	Dam: 6 x 200 MW Francis pump-turbine Canal: 5 x 50 MW Kaplan-type[1]

Installed capacity	1,450 MW The Sardar Sarovar Dam is a gravity dam on the Narmada River near Navagam, Gujarat in India. It is the largest dam and part of the Narmada Valley Project, a large hydraulic engineering project involving the construction of a series of large irrigation and hydroelectric multi-purpose dams on the Narmada River. The project took form in 1979 as part of a development scheme to increase irrigation and produce hydroelectricity. One of the 30 dams planned on river Narmada, Sardar Sarovar Dam (SSD) is the largest structure to be built. It has a proposed final height of 163 m (535 ft) from foundation.[2] The project will irrigate more than 18,000 km2 (6,900 sq mi), most of it in drought prone areas of Kutch and Saurashtra. The dam's main power plant houses six 200 MW Francis pump-turbines to generate electricity and afford a pumped-storage capability. Additionally, a power plant on the intake for the main canal contains five 50 MW Kaplan turbine-generators. The total installed capacity of the power facilities is 1,450 MW. It is the second largest concrete gravity dam (by volume) after Grand Coulee Dam in the US and has world's third largest spillway discharging capacity Narmada Canal The dam will irrigate 17,920 km2 (6,920 sq mi) of land spread over 12 districts, 62 talukas, and 3,393 villages (75% of which is drought-prone areas) in Gujarat and 730 km2 (280 sq mi) in the arid areas of Barmer and Jalore districts of Rajasthan. The dam will also provide flood protection to riverine reaches measuring 30,000 ha (74,000 acres) covering 210 villages and Bharuch city and a population of 400,000 in Gujarat. Solar power generation The government of Gujarat plans to generate solar power by placing solar panels over the canal, making it beneficial for the surrounding villages to get power and also helping to reduce the evaporation of water. The first phase consists of covering 25 km to generate 25 MW of power. Height increases •	In February 1999, the Supreme Court of India gave the go ahead for the dam's height to be raised to 88 m (289 ft) from the initial 80 m (260 ft). •	In October 2000 again, in a 2-to-1 majority judgment in the Supreme Court, the government was allowed to construct the dam up to 90 m (300 ft). •	In May 2002, the Narmada Control Authority approved increasing the height of the dam to 95 m (312 ft). •	In March 2004, the Authority allowed a 15 m (49 ft) height increase to 110 m (360 ft). •	In March 2006, the Narmada Control Authority gave clearance for the height of the dam to increased from 110.64 m (363.0 ft) to 121.92 m (400.0 ft). This came after 2003 when the Supreme Court of India refused allow the height of the dam to increase again. •	In August 2013, heavy rains raised the reservoir level to 131.5 m (431 ft), which forced 7,000 villagers upstream along the Narmada River to relocate. •	On June 2014, Narmada Control Authority gave the final clearance to raise the height from 121.92 m (400.0 ft) metres to 138.68 m (455.0 ft) Srisailam Dam

Location	Srisailam, Kurnool district, Andhra Pradesh, India

Coordinates	16°05′13″N 78°53′50″E / 16.08694°N 78.89722°E / 16.08694; 78.89722Coordinates: 16°05′13″N 78°53′50″E / 16.08694°N 78.89722°E / 16.08694; 78.89722

Construction began	1960 Opening date	1981 Operator(s)	Andhra Pradesh Irrigation Department Dam and spillways Impounds	Krishna River

Height	145.10 m (476 ft)[1][2]

Length	512 m (1,680 ft) Reservoir Creates	Srisailam Reservoir Catchment area 206,040 km2 (79,550 sq mi) Surface area	800 km2 (310 sq mi) Power station Turbines	6 × 150MW reversible Francis-type (left bank) 7 × 110MW Francis type(right bank)

Installed capacity	1,670 MW

The Srisailam Dam is a dam constructed across the Krishna River at Srisailam in the Kurnool district in the state of Andhra Pradesh in India and is the 3rd largest capacity hydroelectric project in the country. The dam was constructed in a deep gorge in the Nallamala Hills in Kurnool district, 300 m (980 ft) above sea level. It is 512 m (1,680 ft) long, 269.748 m (885.00 ft) high and has 12 radial crest gates. It has a reservoir of 800 km2 (310 sq mi). The left bank power station houses 6 × 150 MW reversible Francis-pump turbines (for pumped-storage) and the right bank contains 7 × 110 MW Francis-turbine generators. Project history The Srisailam project began in 1960, initially as a power project, across the Krishna, near Srisailam in Kurnool District, Andhra Pradesh. After several delays, the main dam was finally completed twenty years later in 1981. In the meantime the project was converted into a multipurpose facility with a generating capacity of 770 MW by its second stage which was expected to be completed in 1987. The dam is to provide water for an estimated 2,000 km2 (770 sq mi) with its catchment area of 206,040 km2 (79,552 sq mi) and water spread of 1,595 km2 (616 sq mi). Under the right branch canal 790 km2 (310 sq mi) in Kurnool and Kadapa districts will have assured irrigation. From the initial modest estimate of Rs.384.7 million for a power project the total cost of the multipurpose project was estimated to cross Rs.10 billion in its enlarged form. The 269.748 m (885 ft) high and 512 m (1,680 ft) wide dam has alone cost Rs.4.04 billion together with the installation of four generating sets of 110 MW each. The right branch canal is estimated to cost Rs.4.49 billion and the initial investment of Rs.1.4 billion has been provided by the World Bank. The projected cost-benefit ratio of the project has been worked out at 1:1.91 at 10% interest on capital outlay.[citation needed]. On 2 October 2009, Srisailam dam experienced a record inflow which threatened the dam. Project has an estimated capacity to hold 178.74 thousand million cubic feet. The Advantages of Dams - Pros Hydro Electric Power It's pretty hard to ignore the main benefit that larger dams provide; a way to produce essentually 'green' (clean) electricity. This is usually the main draw for the building of dams in the first place and the influx of power for a town to use and sell can cause cities to grow and thrive. Tourism and Camping Dams are a great draw for tourists and provide an attractive place for families to go camping and fishing etc. This can improve the local economy of an area by attracting travellers who will often spend money at the nearby businesses, and will hence provide more jobs for locas as more labour is needed to keep the tourists 'happy' -- with Hotels etc. Still Water for Animals Some species of animal actually require still water in order to survive. As such, a dam can provide a way for these species to thrive in an area where they otherwise might not have. However, you will see later in this article that dams also cause problems for other such species. Clean Drinking Water for Nearby Cities and Towns Dams can provide a very good source of water for towns and cities in the area. This water can be used for drinking or industry and can take advantage of an otherwise unusable water source. Flooding and Water Management They can also be specifically designed to help ease and solve flooding problems within a settled area, and through the dam -- the water can be controlled to provide a form of irrigation for agricultural land and even source of transportation for goods. The Disadvantages of Dams - Cons Expensive and Difficulties in Becoming Profitable The larger dams are incredibly expensive to build and, as such, they can take many years to pay for themselves and become profitable. Most dams are estimated to operate for at least two to three decades, if not more, to become profitable and this is a cost that is usually taken on by the government and the taxpayers. This debt can be a large burden on the government for a long time and can influence fiscal polices for the life of the debt -- not to mention the potential unforessen maintenance costs. Disruption to Natural Environment and Water Ecology During Construction Building a dam requires diverting water temporarily and it also means a lot of digging and construction on the dam site. While this construction is only temporary, it can have long lasting effects on the environment -- and potentially harm or worse still destroy local ecosystems. Geological Disruption and Earthquakes The Hoover dam is the perfect example of the geological disruption that can be caused by larger dams. The weight of the Hoover dam has actually resulted in the compression of the earth in that area. This has had follow on effects such as minor earthquakes and tremors in the area around the dam. This effect could potentially become more serious over time. Danger of Dam Breaches Dams being built today are much more stable than dams built in the past but many older dams have problems with breaches or even collapses. Because of the large volumes of water behind these dams this can cause catastrophes for nearby people and wildlife. Disruption of Fish Ecology Most dams can cause complete death of migratory fish in the area since they are no longer able to head up stream to breed or feed. Some dam designs allow for this migration to continue somewhat normally but these are usually more expensive and complex to build. The disruption to the salmon breeding cycles in areas with many dams is the largest known impact of this though many other species are negatively impacted as well. Impacted by Drought In times of heavy drought dams will stop functioning properly and some can even lose their structural integrity. If local cities rely on the dam for their power then droughts can be devastating with both power and water becoming scarce. This means that most dam-powered towns and cities must have access to an alternative power source, which can potentially negate the positive effects of the dam in the first place. Affects on Water Quality and Flow Low oxygen levels in dam water are the result of the hydroelectric production process. The disruption of the natural flow of water can have impacts on the turbidity of water as well, which can seriously harm aquatic life.

CONCLUSION ”The future of major and medium irrigation is dim and the country has neither the resources nor the time for creating additional gross potential of some 26 million hectares irrigation through this route. Hence, minor irrigation, particularly through the ground water, must be the mainstay for all future programmes”. From the above it’s quite clear that despite the so-called “Impressive achievements” the support in the favor of the multipurpose river valley projects, bodes ill for the future of the country. Not to put too fine a point on it, the above points lend colors to the Frankenstein image of these projects. So it behooves us to shift our emphasis from major and medium irrigation projects to minor irrigation projects, which have many advantages over the former ones such as no wastage of land in the distributaries, no soil degradation(no water-logging and salinity). Besides, the minor irrigation is more economical and efficient. The key to better management, therefore, lies not in big dams at exorbitant financial and ecological costs, but in minor irrigation which ensures maximum use of ground water and better control over irrigation sources. In recent years many fundamental questions have been raised about the conventional emphasis on multipurpose river valley projects. It behoves us to have the retrospection of our irrigation policy and formulate new constructive policies.