Tungabhadra Project canal command area

Central Ground Water Board,SR, Hyderabadad has carried out the studies during the years 1992-1996 and taken up an area of 6,354 sq.kmin Tungabhadra Irrigation Project Right Bank Canal Command area in parts of Bellary district of Karnataka and Kurnool and Anantapur districts of Andhra Pradesh. Geologically the area is underlain by ancient rocks of Archaean to Pre-Cambrian age and includes Peninsular Gneissic Complex, Dharwar Schists and Kurnool meta sediments. Originally a command area of 1,54,385 ha is envisasged under this project wich is distributed sporadically to benefit large number of villages. In the real practice, a total area of 1,69,345., is irrigated which also includes non-envisaged command especially in the upper reaches of main and distributary canals resulting in canal water shortage area of 59,543 ha (i.e., 39% of the localised command. To mitigate the problems of canal water scarcity areas in the command, feasible zones where ground water can be developed were demarcated. Optimal Conjunctive Use Plan was evolved by ground water development through 11,750 borewells with a well spacing of 250 m and 22,500 dug wells of 6 m dia and 10 m depth with a spacing norms of 160 m between the wells. The financial component for implementation of these plans would be Rs.236 croes (one time investment) yielding annual incremental benefits of Rs. 280 crores for the assured 18 years life of the gound water structures and benefit-cost ratios of about 3.45.

Nagarjuna sagar Project Canal Command area

Conjunctive use studies were carried out during the years 1998-2001 covering Nalgonda, Krishna and Khammam districts in left bank canal command area in the right bank canal. The study area lies between North latitudes 16 15 to 17 15 and East longitudes by 79 10 to 80 20 and falls in survey of India topographic map no.s 56P,56O,65 C and 65 D. Climatologically the area is classified as semi-arid and the average annual rainfall is 773 mm. The Peninsular Gneissic Complex, Younger intrusive rocks (Dolerites), the Cuddapa and Kurnool Group of formations (shales and limestones). Alluvial formations of Recenst Age also occur along major stream courses. The study area is covered by Nagarjuna Sagar Canal net work. The left bank canal runs for 177 km with a designed discharge of 6643.73 MCM and the right bank canal runs for 81 km with a designed discharge of 2126.62 MCM. Major crops grown in the study area are paddy, chillies, cotton, tobacco and other dry crops. The exploration carried out in the study area revealed the productive fracdture zones within 50-60 m. depths where as in limestone formations these extend down to 80-100m. with an yield ranging from 2 lps to 7.5 lps. On the basis of canal water releases int he study area the surface water availability has been estimated as 3,806 MCM. The ground water potential has been estimated on the basis of GEC 1997 methodology and is estimated as 1,007 MCM and thus the total water resources available in the study area are 4,813 MCM. The actual area interpreted from satellite imagery studies is 4,736 sq.km. Based on the crop water requirements the water demands for irrrigation were worked out tobe 2,303 MCM. Therefore 2,510 MCM of water is still available for irrigation. Good management techniques suggested for bringing more areas under irrigation by utilizing the available resources. The modelling studies have confirmed the fact that the ground water development plan can be implemented safely without bringing any undesirable effects of ground water regime. By implementing the plans suggested in the modelling studies an additional fea of 63,958 ha. can be brought under irrigation through a ground water draft of 284 MCM in Kharif and 553 MCM in Rabi seasons after losing 150 MCM as outflow. The investment cost for implementing this plan would be Rs. 107.8 crores. The total annual incremental benefits for athis plan would be Rs. 313.8 crores. The benefit-cost ratio works out to be 2.9. The chemical quality of ground water is generally good for irrigation and drinking purposes.

Sriram Sagar Canal Command area

Conjunctive use studies were carried out in parts of Sri Ram Sgar Canal Command area in parts of Karimnagar and Warangal district covering an area of 1,680 sq.km during the years 2002-2005. The study area lies between North latitudes 18 00 to 18 24 and East longitudes 79 09 to 79 47 and is covered by distributaries no. DBM 1 to DBM 31 on Kakatiya Main canal from 146 KM to 234 KM starting from Lower Manair Dam of Karimnagar districts and serves the needs both for domestinc and irrigation of Karimnagar and Warangal districts of Andhra Pradesh. The total gross command area of the study area is 1,68,000 ha with localised ayacut of 90,614 ha. The area is mainly drained by Maneru river and its tributaries. The geophysical studies in the study area reveals that the rocks in the command area of Sri Ram sagar Canal command area and are considerably permeable with weathering and fracturing. The depth of weathering ranges from 10 t0 15 m. and the potential fracture zones exists within sthe depth range of 15 to 50 m,. respectively. The surface water availability ahs been estimated mainly on the basis of canal water releases and has been worked out as 568 MCM. Teh ground water potential has been estimated on the bsis of GEC 1997 methodology and is estimated as 483 MCM and thus the total water resources avaiable in the project area has been estimated as 742MCM. Thsi can be met with the available surface water resources of 568 MCM creating additional irrigation potential of another 31,000 ha. with the help of constructing additional no. of 20,600 shallow borewells and the present cropping intensity of 40% can be increased to 90%. The investment costs for implementing the proposed conjunctive use plan would be Rs. 80 crores and benefit worked out will be worth of Rs. 240crores and the benefit-cost ratio works out to be 3.07.