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A number of dams and barrages have been constructed and are under construction in the Krishna basin to utilize water resources. Nagarjunasagar and Srisailam are two large terminal reservoirs on Krishna. These two have enough storage to regulate the inflows received in Andhra Pradesh for irrigation and hydropower. The left and right bank canal systems of Nagarjunasagar extend up to Godavari and Pennar delta and are notable examples of intra-basin water transfer. Telugu Ganga canal taking off from the Srisailam reservoir and carrying water up to Tamil Nadu for Chennai water supply is another praiseworthy example of inter-basin transfer with cooperation amongst the states.

Upper Krishna Project Stage – 1

The first stage of the project comprises of two components:

• A dam across the Krishna River near Almatti village in Bagewadi taluk of Bijapur district to storing water up to RL 512.20 m for providing irrigation to an area of 160 Mm².
   

• Another dam across the Krishna River, at Narayanapur (downstream of Almatti Dam) near Bachihal and Siddapur village in Muddebihal taluk of Bijapur district.  A Left Bank Canal from the dam will provide irrigation under to 4,250 Mm² area and the water utilization will be 3,368 Mm³. 

Narayanpur or Upper Krishna Stage I dam is located downstream of Almatti dam after confluence of the Malaprabha and Krishna rivers. A major part of Upper Krishna command is covered under the Narayanpur canals for which, the main supplementing storage would be at Almatti. Narayanpur dam is a composite dam, located at north latitude of 16⁰ 10' 00" and an east longitude of 76⁰ 21' 00" near village Siddapur in Muddebihal Taluka of Bijapur district. Narayanpur dam is 10,637.52 m long and 29.72 m high. The catchment area of the reservoir is 47,850 km². The Project provides water for irrigation to the drought prone areas of Bijapur, Bagalkote, Gulbarga, Raichur and Koppal Districts. This project has been taken up in two stages.

Salient features of Narayanpur dam

Upper Krishna Project Stage – 2

The second stage of the project envisages raising FRL of Almatti Dam to 524.26 m to utilize further quantum of 1,907 MCM for providing irrigation to an additional area of 1,972 Mm². However, the state of Maharashtra claims that in case the reservoir water level rises beyond 519.6 m, there will be submergence in Maharashtra which a violation of the stipulation that the reservoir should not cause any submergence in its territory.

Almatti dam of Upper Krishna project is located on the Krishna River about 10 km downstream of the confluence of its tributary Ghatprabha. The Almatti dam is located at a north latitude of 16⁰ 19' 48" N and east longitude of 75⁰ 53' 15" E near village Almatti in Bagewadi Taluka of Bijapur district. This is a 49.29 m high composite dam of length 1,565 m. The catchment area of the dam is 35,925 km². Irrigation and hydropower generation are planned at Almatti dam apart from ensuring releases for the Narayanpur dam which is downstream to it.

The power house at Almatti has 5 units of 55 MW each and one unit of 15 MW, totaling 290 MW. The MDDL varies from 505.97 to 511.16 m and the tail race level is 489.0 m. For the 55 MW units, the rated head is 26.6 m and for the 15 MW unit, it is 24.0 m.

Salient features of Almatti dam.

Srisailam Dam

The Srisailam project, renamed as ‘Neelam Sanjiva Reddy Sagar’ in the honour of the former president of India, was originally planned as hydroelectric project by the Govt. of Andhra Pradesh. Subsequently, the domestic water supplies to Chennai and irrigation benefits to upland areas have been included. This is a part of the scheme for integrated development of the water resources of river Krishna in the state of Andhra Pradesh. The dam is located near the famous shrine ‘Srisailam’ known as “South Benaras” after the confluence of Tungabhadra and Bhima rivers with the Krishna. Srisailam village is about 200 km south of Hyderabad and the Srisailam dam is situated at about 869 km downstream of the origin of Krishna River where the catchment area is 211,700 km².

The project involves the construction of a masonry dam of straight gravity type with an overall length of 512 m and a maximum height of about 144 m from the deepest foundation level. The reservoir formed behind the dam has a storage capacity of 8,720 Mm³. The spillway portion is 266.4 m long having 12 bays of 18.3 m clear span each and controlled by 18.3 m x 16.7 m radial gates. It has a discharging capacity of 37,380 m³/s. The non-overflow of the dam is on either side of spillway portion. At FRL of 269.75 m, the storage capacity is 8,723 Mm³. The dead storage level of the dam is 260.3 m and live storage is 7,080 Mm³. The catchment area at the dam is 203,600 km².

Two powerhouses are located near the dam. At the right bank powerhouse, 7 units of 110 MW each have been installed while the left bank powerhouse has 6 units of 150 MW each. The powerhouses were submerged in a flood in 1998 which caused extensive damage to them. When the Srisailam reservoir touches FRL, the backwater extends up to the Kurnool town. Fishing is also carried out in the reservoir and some recreation facilities are being setup. From the Srisailam reservoir, planned annual irrigation is 3,100 Mm², utilizing about 2,209 Mm³ of water. A noteworthy feature of this dam is that nearly 5.9 km³ of water is stored against the gates.  Thus, a large quantity of water is not stored against a passive wall but against a ‘live’ and moving device. Recall that Ukai dam (Chapter 12) is another large dam where enormous volume of water is held behind gates.

In summer months, the river flows dwindle down to less than 30 m³/s. The maximum flood observed in Krishna River at the dam site is of the order of 18,500 m³/s during monsoon period (June-October). During the construction, a problem of deciding river diversion arrangements arose. The maximum river discharge data for fifteen consecutive years were studied to select the optimum discharge which would give the largest working period. Finally, diversion arrangements were designed for about 850 m³/s capacity which ensured about 195 working days during the period from Nov - June.

The diversion arrangements finally adopted comprised­ of: A 9.14 m diameter circular tunnel of 567 m³/s capacity through the left abutment; a diversion channel of 15.24 m bed width to carry the balance of 283 m³/s; and two semi-permanent concrete upstream and downstream cofferdams to divert the river flows for isolation of the construction area.

Pulichintala Project

The Pulichintala project was originally investigated as an irrigation project. But due to construction of Nagarjunasagar dam, this project was not taken up as the entire ayacut that was originally to be irrigated under Pulichintala project was covered by Nagarjunasagar project. The present proposal is to construct a dam to stabilize irrigation in the existing ayacut in the Krishna delta for the paddy. Hydropower generation by utilizing the irrigation releases for the delta is also planned by using installed capacity of 60 MW.

At the proposed site, the catchment area is 240,733 km². The FRL of the reservoir will be at 53.34 m and MDDL at 42.67 m. Pulichintala reservoir will have gross storage capacity of 1,296 Mm³ and a live storage of 1,026 Mm³.

Nagarjunasagar Project (NSP)

The Nagarjunasagar project is the largest and highest masonry dam (125 m) in the world. It is situated downstream of Srisailam reservoir on the main Krishna river in Andhra Pradesh. It is a multipurpose project with irrigation, hydropower and flood control components.

The Nagarjunasagar dam is Located near Nandikonda village, Pedavoora Mandal, Nalgonda district, latitude is 16º 34' 24" N and longitude 79º18' 47" E. It is one of the dams whose height is more than 100 m; it is 124.663 m above the deepest foundation level. The catchment area at the dam at 215,193 km²; the annual rainfall in the catchment is 889 mm, the maximum observed flood is 30,050 cumec, and the design flood (return period 1,000 year) is 58,340 cumec. For the reservoir, the FRL, DSL, and MDDL of the reservoir are at 179.83 m, 121.92 m, and 156.36 m, respectively. For this reservoir, the maximum storage is 11,555 Mm³ and the live storage is 6,940 Mm³. Spillway at the masonry dam is 470.916 m long and has its crest at 166.421 m. It is equipped with 26 gates of size 13.71 m × 13.14 m. When the Nagarjunasagar reservoir is full, its backwater extends up to the Srisailam dam and covers an area of 285 sq. km.

Nagarjunasagar project complex has substantial capacity for hydropower generation. It has one conventional and seven reversible units, each with 110 MW capacity. The right bank canal power house has 3 units of 30 MW each and left canal power house has 2 units of 20 MW each.

On an average, the Nagarjunasagar project will annually provide irrigation to a command of 12,480 Mm² ha by utilizing 7,465 Mm³ water. The work on the project was completed in 1974. The project comprises a dam with two canals taking off on either side. The Nagarjunasagar Right Main (Jawahar) Canal is 203 km long and envisages creating irrigation potential in an area of 4,750 Mm² in Guntur and Prakasam districts. The Nagarjunasagar Left Main (Lal Bahadur) Canal is 179 m long and envisages creating irrigation potential in an area of 4,200 Mm² in Nalgonda, Khammam and Krishna districts. Each of these canals can carry maximum discharge of 311.5 cumec. The irrigation potential created by June 1999 was 8,100 Mm².

Ghatprabha Dam

The Ghatprabha project comprises three stages. The first stage consists of a 71 km long left bank canal from the Dupdhal weir constructed across Ghataprabha River in 1897 near Dupdhal for providing irrigation to an extent of 425 Mm². The second stage comprises of extension of left bank canal from km 72 to its full length of 109 km and a dam across Ghatprabha River near Hidkal, up to a partial height of RL 650.14 m. The Ghatprabha dam is located near Hidkal town in Hukkeri taluk of Belgaum district at latitude 16⁰ 9’ 0’’ N and longitude 74⁰ 38’ 0’’ E. At the dam site, the catchment area is 1,412 km² and the water yield is 1,970.38 Mm³.

Ghatprabha dam has a live storage capacity of 1,387 Mm³ to provide irrigation to a total area of 1,396 Mm², inclusive of the area under stage I. The third stage involves raising the FRL of Hidkal dam to its final level of RL 662.94 m (RL 2,175.00 feet) thereby creating gross storage of 1,448 MCM and constructing a 202 km long Right Bank Canal and 86 km long Chickkodi Branch Canal to irrigate 1,913.86 Mm². Thus, the total command area under the project comes to 3,310 Mm².

Salient features of the Ghatprabha (Hidkal) dam.

Tungabhadra Project

Tungabhadra is the largest tributary of the Krishna River which contributes an annual discharge of 14,700 Mm³ at its confluence with the main river. The Tungabhadra dam is located at Mallapuram, 5 km away from Hospet in the Bellary district. The latitude and longitude of the dam are 15⁰ 15’ 0’’ N and 76⁰ 21’ 0” E, respectively. With full reservoir level of 497.74 m above MSL, the reservoir extends over 378.14 Mm². The catchment up to the dam site is 28,168 km². The annual rainfall in the upper catchment of the river is 104 cm. Minor rivers that feed the Tungabhadra River are dammed at many places, creating small to medium sized reservoirs, such as Vanivilas Sagar and Anjanapur, and several large tanks, such as Shantisagar and Madag. The river carries large amount of silt and therefore, silt deposition in the reservoir is high. This has reduced the capacity of the reservoir by 13.5% in its first decade of existence.

Salient features of the Tungabhadra project

The climate at the reservoir site is mainly dry (humidity 80.7% to 93.7%); the average monthly maximum and minimum air temperatures ranging from 31.0 to 39.5°C and 13.8°C to 22.3°C, respectively. The water remains warm (23.1 to 29.5°C) throughout the year.

Vanivilas Sagar Project

Vanivilas Sagar dam is situated on the Vedavati River in Chitradurga district, about 104 km northeast of the Babudan Hills (the source of the Vedavati River). Created in 1901, it is one of the oldest reservoirs in the State. Total Catchment area at the dam site is 5,374.00 km² and the independent catchment area is 1,554 km². Mean annual precipitation for the catchment is 600.00 mm and mean annual run-off at dam site is 294.49 Mm³. Maximum flood discharge at the dam site has been estimated to be 1,000 cumec. At full reservoir level of 652.28 m, the impoundment has a water spread area of 87.63 km². The latitude and longitude of the dam are 13⁰ 16’ 0’’ N and 75⁰ 16’ 20” E, respectively. In the headwaters area, the river receives high rainfall to the tune of 375 cm per annum. However, the precipitation in the local catchment is just 60 cm per year, as the reservoir is situated in the semi-arid plains.

Salient features of Vanivilas Sagar project

The reservoir water is uniformly warm throughout the year (22.3 to 26.3 °C) and no thermal stratification develops. The pH of the water usually lies in the range 8.4 – 8.5.

Bennihora Project

Bennihora project is a major river valley projects across Bhima River, a tributary of Krishna River. The dam is located in Chithapur Taluk, Gulbarga District. Its latitude is 17º 27' 00" N and longitude 77º 01' 00" E. The catchment area of the reservoir is 2,204.09 km².

Salient features of Bennihora Project  

Bhadha Reservoir Project

This is a major multipurpose river valley project across the Tungabhadra River. The dam is located near Lakkavalli village in Tarikere Taluk, of Chickamagalur District, and its latitude is 13º 42’00’’ N and longitude 75º 38’20” E. The catchment area of the reservoir is 1,968 km².

Salient features of Bhadha Reservoir Project

Bhima Irrigation Project 

The Bhima project is a major river valley projects across Bhima River, a tributary of Krishna River near, near Ujjani Village in Solapur District. The dam is located at latitude 18º 4' 26" N and longitude 75º 07' 15" E. The gross catchment area of the reservoir is 14,856 km² and the free catchment area is 9,766 sq. km.

Salient features of Bhima Project 

Hipparagi Barrage

The Hipparagi Barrage project is located near village Hipparagi, in Jamakhandi Taluka of Bijapur district. The latitude and longitude of the barrage are 16º 33' 00" N 75º10' 00" E, respectively. The catchment area at the barrage is 22,699 km².

Salient features of Hipparagi Barrage

xiii. Malprabha Project

This project is located on the Malprabha tributary of Krishna River, near village Navilutheertha, in Saundatti Taluka of Belgaum district. The latitude and longitude of the barrage are 15⁰ 49’ 00’’ N and 75⁰ 6’ 0” E, respectively. The catchment area of the reservoir is 2,564 km².

Salient features of Malprabha Project

xiv. Upper Tunga Project

This project is located near Shimoga Taluka of Shimoga district, 100 m downstream of existing Anicut.

Salient features of Upper Tunga project

Koyna dam

Koyna is multipurpose masonry gravity dam on Koyna River, located at a distance of 20 km from Chiplun, in Ratangiri District, Maharashtra. The catchment area at the dam is 891.78 km². The height of the dam is 85.35 m. The reservoir has a live storage capacity of 2,662 MCM at FRL which is at 650.85 m and the MDDL is at 609.50 m. The mean annual inflow at Koyna dam is 4,745 MCM. Four power houses have been constructed under this scheme. Koyna I & II power houses have 4 units of 65 MW and 4 units of 75 MW each with a total installed capacity of 560 MW. Koyna III power house has 4 unit of 80 MW each and Koyna IV power house has 4 units of 250 MW each.

Markendaya Project

The Markendaya project is located on Ghatprabha tributary of Krishna River, near village Shirur in Hukkeri Taluka of Belgaum district.  The latitude and longitude of the barrage are 16⁰02’00’’ N and 74⁰ 38’ 33” E, respectively. The catchment area at the project side is 432 km².

Salient features of Markendaya Project 

Singatalur Lift Irrigation

The Singatalur Lift Irrigation project is located on Tungabhadra River near village Hammige, in Mundaragi Taluka of Gadag district.  The latitude and longitude of the barrage are 15⁰ 02’ 00’’ N and 75⁰ 50’ 0” E respectively. The catchment area at the project is 19,850 km².

Salient features of Singatalur Lift Irrigation Project 

Krishna Irrigation Project

The Krishna Irrigation Project covers Satara and Sangli Districts in Southern Maharashtra. The project consists of two storage dams across the Krishna River (Dhom) and its tributary Venna River (Kanher) for irrigation in downstream semi-arid and arid zones as well as industrial water supply to Wai and Karad towns.

The Krishna Irrigation Project (K.I.P.) was cleared for implementation in the year 1966. The proposed water utilization of the Krishna Irrigation Project with three storage reservoirs was 1,051.54 Mm³. However, in view of the reduced quantum of water from the Krishna basin allotted to Maharashtra State as a result of Krishna tribunal award (year 1974-75), it was decided to reduce the utilization of Krishna irrigation project to 849.62 Mm³.

The Krishna irrigation project’s catchment area of the storages and command area lies in between latitude 17º 0’ N and 18º 0’N; and longitude 73º 45’E to 74º 45’E.  This command area can be classified in the three groups:

•   Having normal annual rainfall 700 to 800 mm;

•   Having normal annual rainfall 400 to 500 mm (semi arid zone), and

•   Having normal annual rainfall below 400 mm (arid zone).

Kanher and Dhom command area falls under the 1^st category. Arphal command area up to 40 km falls under the 1^st category, from 40 km to 100 km comes under the 2^nd category, and beyond 175 km of the Arphal left bank canal, the area is under the 3^rd category.

Annual rainfall in the command area varies from 700 to 800 mm; it is less than 400 mm in the tail reach. Nearly 75% of annual rain falls during the months of June to September.  Average annual runoff at Dhom reservoir site is 423.30 Mm³. Catchment area at Dhom dam site is 217.56 km². Average annual runoff at Kanher reservoir (Venna River) site is 483.60 MCM and the catchment area at this dam is 204.69 km².

Part of the command area of this project is under semi-arid and arid zone. Demand for irrigation water in arid zone from Krishna irrigation project has increased due to increase in irrigation area. Reservation of water from Krishna irrigation project storages for the industrial area (Wai and Karad towns) has also increased. But the reduced water allocation for Krishna irrigation project necessitated the revision of water planning for the project whole. The 75% dependable yield from the two storages viz. Dhom and Kanher is approximately 822.15 MCM.  The quantum of water available is not adequate to cater to all demands of extending irrigation facilities (Dhom command, Kanher command, Arphal command) and reserving water for industrial area (Wai and Karad).  Hence it is necessary to use the available water optimally.

Accordingly, the project planning was changed by deleting storage scheme at Borkhal; reducing the water losses in conveyance by lining the canals; deleting some of the command area under the Arphal left bank canal; diluting the crop pattern and extending the irrigation facilities to the more command area; and reserving the water for industrial area at Wai and Karad. Jowar, groundnut and pulses are major Kharif crops, and the major Rabi crop is Jowar (local) or hybrid variety; and well irrigation for perennial crop is only practiced in the Dhom and Kanher command area.

Osmansagar Reservoir

The Osmansagar reservoir is situated near Gandipet village in Rangareddy district, AP, at latitude and longitude 17° 22' 30" and 78° 22' 0" respectively. It was constructed across Musi River in the year 1920 with live capacity of 156.81 MCM and gross storage capacity of 180.54 MCM. The designed maximum flood discharge is 2,971 cumec. Though the main purpose of the reservoir at the time of construction was to absorb flood water but it is now serving as a water supply source to the twin cities of Hyderabad and Secunderabad. The catchment area up to Osmansagar is 738.15 sq. km comprising 637.14 sq. km free and rest of 101.01 sq. km intercepted.

Salient features of Osmansagar Reservoir

According to the sedimentation study made by Vishwantaham and Eashwaraiah (2004) through remote sensing, the current live storage capacity of Osmansagar reservoir is 100.19 MCM and the loss of live capacity works out to 56.63 MCM over a period of 82 years. The average annual loss of live capacity is approximately at the rate of 0.7 MCM/year.

Prakasam Barrage

This barrage is the terminal structure on the Krishna River to meet the delta requirements in the Krishna basin. It has been named after a former chief minister of the Andhra Pradesh. The barrage is located near Vijayawada in Andhra Pradesh. At the barrage, the catchment area is 257,078 km² and the pond level is 17.4 m. Prakasam barrage provides irrigation to a command of 4,450 Mm² utilizing 5,132 Mm³ of water.