Estimation and Analysis of Return Flows: Case Study

Return flows from irrigation form an important component in the overall management of water in a basin. The Nagarjunasagar irrigation project is one of the biggest irrigation projects in India. At the Nagarjunasagar project formulation stage, the return flows were assumed to be 7.5% of the total water drawn into the command area (area irrigated under the canal), which could be approximately 538.08×106 m3. This paper aims to calculate the return flows from the Nagarjunasagar canal command areas. At present, the calculations are made during the period 1982–2004 by using multiple linear regression analysis. Return flows form 15% of the total releases from the canals for the whole study period. During wet, normal, and dry periods, return flows are 29, 20, and 10%, respectively. Similarly, they are 29 and 18% during the kharif (June–October) and rabi (October–February) seasons, respectively.