Rooftop Rainwater Harvesting for Providing Life Saving Irrigation to the Horticultural Crops

摘要

The present study was conducted during August 2001 to June 2002 at Dryland Research Farm of Chaudhry Charan Singh Haryana Agricultural University, Hisar. The probability analysis of rainfall data was carried out on seasonal basis (July-September) for23 years (1977-1999) by using Weibulls formula. The seasonal rainfall amount was predicted at three probability levels viz., 25, 50 and 75% and was found as 342.1, 284.4 and 250.6 mm, respectively. The estimated rooftop runoff for the proposed site witharea 557.7 m~2 at different probability levels viz., 25, 50 and 75% was calculated as 171.7 m~3, 142.7 m~3 and 125.8 m~3, respectively. The dimensions of the storage tank were estimated for storage volume of 142.7 m~3 at the probability level of 50% using Prismoidal formula and finalized as depth 2 m, bottom area 6.3 x 6.3 m~2and top area 10.3 x 10.3 m~2. The crop water requirement for the horticultural crops like aonla, guava, ber and pomegranate was calculated for fully grown plant and canopy area wasassumed 40% of the spacing. The average plant to plant spacing was assumed 6 x 6 m and total number of plants was 31. Total crop water requirement was estimated 0.57, 0.52, 0.78, 1.31, 2.26 m~3/day for December, January, February, March and April, respectively. Stored water amount was sufficient for providing irrigation from December to mid April through drip irrigation system. Three drippers with discharge of 8 1/h were proposed to be installed per plant. The time of operation for drip irrigation system was calculated as 51 min for December and January, 1 h 9.6 min, 1 h 57.6 min and 3 h 22.8 min for February, March and April, respectively.