11.73% of water in reservoirs lost due to evaporation: Report
| Date :14-May-2019 |
By Kartik Lokhande:
IN summers, hopes of citizens, farmers, and industries are pinned on release of water from irrigation projects. However, not many are aware that even the unutilised water in irrigation reservoirs is lost due to evaporation in the intense heat. The latest Water Audit report for the year 2016-17, released in March 2019, pegs the evaporation losses for irrigation projects in Maharashtra at an average 11.73 per cent of gross storage. As per the report, the gross storage of irrigation projects in the State is 37,738 Million Cubic Metre (Mcum).
As against this, the evaporation losses are 4,428 Mcum, which is 11.73 per cent of the gross storage. As far as the data for various administrative divisions in the State is concerned, Amravati division tops the chart with evaporation losses of 21.21 per cent, followed by Aurangabad with 16.75 per cent evaporation losses, and Nagpur being at third position with evaporation losses at 14.74 per cent. Evaporation losses are pegged at 914 Mcum for medium projects in the State. Of this, evaporation loss for Nagpur and Amravati divisions is 124 Mcum and 162 Mcum.
For minor projects, evaporation losses are pegged at 816 Mcum. The loss for minor projects in Nagpur and Amravati divisions is 88 Mcum and 203 Mcum respectively. If one goes by project-wise details, Pench project complex has evaporation losses estimated to be 77.51 Mcum as against designed live storage of 1261.67 Mcum. In case of Lower Wunna complex, evaporation losses are 37.30 Mcum as against designed live storage of 188.08 Mcum. Bagh complex has designed live storage of 229.36 Mcum and evaporation losses are estimated to be 26.45 Mcum. Itiadoh project has 82.23 Mcum evaporation losses as against designed live storage of 317.87 Mcum.
The evaporation losses for Bor project are pegged at 5.11 Mcum as against designed live storage of 127.42 Mcum. In case of Dina project, designed live storage is 67.54 Mcum and 5.98 Mcum water is lost due to evaporation. Lower Wardha project loses 29.50 Mcum water to evaporation as compared to designed live storage of 216.87 Mcum. The project-wise evaporation losses for some other important projects in Vidarbha region are as follows: Katepurna -- 12.24 Mcum (as against designed live storage of 86.35 Mcum), Khadakpurna -- 28.24 Mcum (designed live storage of 93.40 Mcum), Nalganga -- 6.76 Mcum (69.32 Mcum), Pentakli -- 6.97 Mcum (59.97 Mcum), Wan -- 6.50 Mcum (81.96 Mcum), Upper Wardha -- 116.40 Mcum (564.05 Mcum), Arunawati -- 26.20 Mcum (169.67 Mcum), Bembla -- 62 Mcum (302.67 Mcum), and Pus -- 13.82 Mcum (91.28 Mcum).
However, the Water Audit report mentions that there is a ‘large variation’ in actual evaporation compared to projected evaporation. In case of Upper Wardha project, the percent variation is as high as 170. The percent variation in case of some other major projects is as follows: Wan (146), Upper Prawara complex (146), Kanher (136), Ulshi (156), and Urmodi (162). Following this, the Water Audit report advises the field authorities to ‘review’ the actual evaporation occurred as compared to projected evaporation and take necessary action.
Also, to have realistic evaporation data, field authorities have been asked to install Pan evaporimeter for evaporation data collection and calculating this loss using relevant coefficient for this purpose. The Water Audit report was prepared after consolidating and analysing water accounts of 64 major irrigation projects, 254 medium projects, and 2,186 minor projects. Some of the projects like Pench, Lower Wunna, and Bagh in Vidarbha are treated as ‘complexes’ as they have more than one reservoir.