Agricultural Engineering Today

The study was undertaken to estimate the roof water harvesting potential of Junagadh Agricultural University (Gujarat) campus using Google Earth and Quantum GIS and to evaluate the demand supply analysis. The total rooftop area of 81 buildings was found as 1,04,012 m². Total roof water harvesting potential of campus was estimated at 44426 kiloliter per year at design rainfall of 66% probability of exceedance and 77,889 kiloliter per year at design rainfall based on monthly average value. Sample calculation of demand supply analysis revealed that roof water harvesting potential at 66% probability of exceedance design rainfall can fulfill 78, 88, 59 and 100% yearly demand of college, hostel, multi storey office and residence i.e. up to 281^st day, 292^nd day, 212^th day and 365^th day of water year from 14844 m², 1110 m², 1036 m² and 294 m² rooftop area, respectively. For residence, 26.58 kiloliter additional water will be available for recharge. For monthly average design rainfall, 3016 kiloliter, 293 kiloliter, 27 kiloliter and 121.17 kiloliter water per year will be available for recharge for college, hostel, multi storey office and residence, respectively in addition to satisfying the yearly water demand. Maximum storage of water required at 66% probability of exceedance design rainfall for college, hostel, multi storey office and residence was found to be 3640.24, 297.7, 192.91 and 92.58 kiloliter, respectively while in case of monthly average design rainfall, it was 8415.93, 636.84, 526.21 and 187.17 kiloliter, respectively. The information on maximum storage required can be used for planning and cost estimation.