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Major Water Resources Projects in Sabarmati Basin         

Sei dam has been constructed on Sei River in the Rajasthan state near village Teja Ka Bas, Kotra tehsil of district Udaipur. This project is also known as Jawai reservoir project. The latitude and longitude of the dam site are 24º 23' N and 73º 11' 8" E. The main objective of this project is to supply water for irrigation in Jawai command area. The water from the catchment up to this dam site is not available for the Dharoi reservoir command.

Harnav Dam

In the head reaches of Harnav River, a gated dam, known as Harnav dam, has been constructed. Also known as Harnav-II dam or Vanaj dam, the dam is located near Vanaj village, in Vijaynagar taluka, Sabarkantha district and has dual purpose of irrigation and flood control. The catchment area at the dam site is 116 sq. km. The dam was completed in the year 1990. The FRL and HFL of the reservoir are at level 332.00 m and 336.85 m, respectively. The dead storage and live storage capacity of the Harnav dam is 1.70 and 19.97 million cubic meter respectively. The crest level of the head regulator for release of water for irrigation from the dam is at 317.50 m.

Three weirs have been constructed between the dam site and Khedbrahma: (i) Mamrechi weir situated 3 km downstream of Harnav dam near Abhapur (ii) Kenyatta weir situated 12 km downstream of Harnav dam at Attarsumba Ashram, and (iii) Chhapra weir or Harnav weir situated 25 km downstream of Harnav dam. The Mamrechi and Kenyatta weirs were constructed by the former princely states. The third weir, namely Chhapra weir, was constructed in 1958 as Harnav-I. There are three gauging sites on Harnav River at Khedbrahma (downstream of Harnav weir) at Abhapur (downstream of Harnav dam) and at Harnav weir. The water requirements at the three weir sites are met from the Harnav dam and the flow from the intermediate catchment. Harnav dam is operated to meet the irrigation demands from these weirs. The Harnav River spills its water directly in the Dharoi reservoir.

Since there is no rain gauge station in the catchment area of the Harnav dam-and no gauging site upstream of the Harnav dam, estimation of inflow in the reservoir is made on the basis of rate of rise or fall of water level in the reservoir.

Harnav Weir

Also known as Harnav-1 or Chhapra weir, the weir is located in district Sabarkantha downstream of Harnav dam and upstream of Khedbrahma. The weir was completed in the year 1959. The catchment area at the weir site is 427 sq. km. This single purpose project has been constructed to cater for irrigation. The spillway of the weir is 191 m long. To supply water in the command area of the Harnav weir, the water at the weir site is diverted in the Damavas and Patera tanks, which have combined, live storage capacity of 2.067 MCM. Thus, water is spilled to the Dharoi reservoir from the Harnav weir after filling the Damavas and Patera tanks to their capacity.

Dharoi Dam

The Dharoi dam is the most important structure of the Sabarmati basin. It is located on Sabarmati River near village Dharoi in Kheralu taluka of district Mehsana, 103 km from the source of the river. The latitude and longitude of the dam are 24º 00' N and 72º 52' E, respectively. Its purposes are water supply to the cities of Ahmedabad and Gandhinagar, irrigation, flood control and power generation. The catchment area of the river at the dam site is 5,540 sq. km. The dam was completed in the year 1976. The FRL and HFL of the dam are at a level of 189.59 m and 175.87 m respectively. The dead storage and live storage capacity of the reservoir (as per revised capacity plan after 50 years) are 131.99 and 775.89 MCM, respectively.

Hathmati Dam

The Hathmati dam is located near Fatehpur village in Bhiloda taluka, Sabarkantha district, and serves dual purpose of irrigation and flood control. The catchment area at the dam site is 595 sq. km. The dam was completed in the year 1972. Along with the Hathmati dam, the Indrasi dam for providing necessary storage and the Navalpur waste weir for disposing off the flood water have also been constructed. The FRL and HFL of the reservoir are at a level of 180.74 m and 183.18 m, respectively. The dead storage and live storage capacity of the Hathmati dam are 3.90 and 148.93 million cubic meters, respectively. The crest level of the head regulator taking off water for irrigation from the dam is at 170.69 m.

The Indrasi dam has been built on the Indrasi River for providing enhanced storage for the Hathmati dam. The dead storage and live storage capacity of this reservoir at a level of 178.76 m (as per revised fresh capacity plan, 1988) are 0.392 and 18.80 million cubic meters, respectively. Above the level 178.76 m, the Hathmati reservoir and the Indrasi reservoir merge together. One head regulator has also been provided in this dam for releasing water for irrigation. The crest level of this head regulator is at a level of 172.21 m.

To dispose off the flood water from the Hathmati reservoir, the Navalpur waste weir has been constructed. The crest level of this ogee shaped weir is at a level of 180.74 m and it is ungated. The length of the spillway is 241 m and its discharging capacity at HFL is 2,943.2 cumec.

Guhai Dam

The Guhai dam is located on Guhai River near village Khandial in Himatnagar taluka of district Sabarkantha, 39 km from the source of the river. The latitude and longitude of the dam are 23º 42' 00" N and 73º 3' 24" E, respectively. Its purposes are irrigation and flood control. The catchment area of the Guhai River at the dam site is 422 sq. km. The dam was completed in the year 1990. The FRL and HFL of the dam are at a level of 173.00 m and 173.77 m respectively. The dead storage and live storage capacity of the reservoir are 5.30 and 57.04 MCM, respectively.

The culturable command area of this project is 11,465 ha and the annual water requirement from this reservoir for irrigation is 44.702 MCM.

Hathmati Weir

The Hathmati weir is located on the downstream of Hathmati dam and Guhai dam but upstream of confluence of Hathmati River, with Sabarmati River. The ogee shaped weir was remodelled in 1972-73. It has the sill level at 134.078 m and an overflow section 306.367 m long. The total catchment area of the weir is 1,357 sq. km. The design discharge of canal head regulator is 19.4 cumec. This weir is used to divert the flow of Hathmati River into the B, C and D zones (See below) of the command area of the Hathmati system for irrigation purposes. During floods, the excess flow of Hathmati River passes over the weir to join the Sabarmati River.

Hathmati canal system is one of the oldest irrigation systems of Gujarat state. The command area of this project comprises of four zones:

• Zone A: New areas in Bhiloda and Himatnagar Taluka of Sabarkantha District under direct command of the reservoir.

• Zone B: Area of existing Hathmati canal system getting water through Himatnagar weir.

• Zone C: New area beyond Bokh between Sabarmati and Khari rivers in Sabarkantha, Gandhinagar and Ahmedabad districts.

• Zone D: Command area of existing Khari cut canal system. The main canal of zone A takes off from the Hathmati dam.

The capacity of the main canal in initial reach is 15.581 cumec. An escape has been provided at chainage 1,425 of main canal to release water in the Hathmati River for B, C and D zones. Upstream of the Hathmati weir, two ancient storage structures, known as Limla dam and Karol dam have been constructed for storing excess water at the Hathmati weir. This water is to be released in the command areas of B, C and D zones. The storage capacity of the Limla dam is 10.28 million cubic meter and that of Karol dam is 7.504 million cubic meters. Thus, water in excess of the irrigation demands of the B, C and D zones at the Hathmati weir can be diverted to fill these two storage structures for use in case of scarcity before spilling the water in Sabarmati River.

A head regulator of 4.816 cumec capacity has been provided in Indrasi dam for releasing water for B, C and D zones. The water released from Hathmati reservoir in the Hathmati River for B, C and D zones either through Indrasi head regulator or through escape of main canal of zone A is picked up at Himatnagar weir and is diverted in the main canal of B-zone.

During floods, water of Hathmati River is diverted in the main canal of zone B at Himatnagar weir and water is stored in Limla dam which is filled through Bokh feeder, taking off from Hathmati canal (zone B) and Karol dam which is being fed through Hathmati main canal and Karol feeder. This stored water is released through head regulator in river Khari for Khari cut canal (zone D) and the same is picked up at Raipur weir.

The main canal of zone C takes off from Bokh feeder of Hathmati main canal of zone B. As such, water diverted in main canal of zone B at Himatnagar weir is utilized in zone B, zone C, and zone D.

Watrak Project

Watrak dam is an earthen dam constructed near Pahadia village, about 19 km upstream of Dhupal Weir. This dam was completed in 1984 with gross and live storage capacities of 177 and 154 million m³. The height of the dam above the deepest foundation to the spillway crest is 36 m. Spillway of the dam is ogee shaped with six gates and has been designed for a flood of 12,798 cumec. FRL of the dam is at 136.25 m and MDDL is at 126.39 m. Two canals take off from the dam to supply water for irrigation. The right bank canal runs for about 23.5 km and irrigates an area of 3,258 ha while the left bank canal has two branches and irrigates an area of 15,103 ha. At FRL, the submergence area is 32 sq. km.

Kalpsaar Project

The Kalpsaar project envisages construction of a dyke in the Gulf of Khambat, to isolate a portion of the gulf, and convert it into a large sweet water lake. As such this project is not in the Sabarmati basin. The project will provide water, generate electricity, and the rail/road on the dyke will also reduce the distance between Mumbai and Saurashtra by 225 km. A noteworthy feature of Kalpsaar is that the dam and the lake are both out in the ocean, and not on the land, so there is no submergence of any land area and consequently displacement etc. In addition, it is also important being tidal power project, one of the alternative and renewable sources of energy.

Besides the above, there are some more existing water resources projects in the basin.

Salient features of selected existing projects in Sabarmati basin.