Planning and Designing of an Integrated Rainwater Harvesting System for a Water Scarce College Campus

摘要

In the present study, integrated rainwater harvesting (RWH) system has been planned and designed fora water scarce college campus located in Tiruchirappalli district, Tamil Nadu. The necessity of RWH in this campus is mainly due to the insufficient availability of surface water as well as groundwater to meet its various demands. The estimated average annual runoff from this 14.6 ha campus for an average annual rainfall of 663 mm is 23,163 m~3, whereas the annual water demand is 60,084 m~3. This shows that the annual water demand could not be met by RWH alone; however the purchasing cost of water can be reduced to an extent of 38%. Hence, there is an urgent need of RWH in this water scarce campus for direct use as well as to augment the ground water resource. Effective storage or recharge through RWH can be achieved with appropriate selection of RWH structures and selection of suitable location. From this study it is found that, if the entire rainfall on a particular boundary having different land use has to be harvested then a single type of RWH structure may not be a best choice. In such places, based on the topography there is a need for integrated rainwater harvesting system. The integrated RWH system in the present study consists of recharge pits, trenches and underground sumps to harvest the rainwater from built-up areas (as the aquifer thickness is very less), and also a percolation pond to harvest the rainwater from the non-built-up areas.