Assessing the effectiveness of rainwater harvesting structures in an urban environment

Proper implementation of rainwater harvesting (RWH) fulfills long term water requirements and its effectiveness has a direct impact on groundwater recharge. This comprehensive study on effectiveness of RWH system within Chennai City, Tamil Nadu, India is done by interconnection with the aquifer, adequacy and recharging capacity into the aquifer. For this purpose, a questionnaire is formulated to collect the details of implemented RWH structures. Analysis of the responses from the individual households is carried and used to develop the spatial distributed map. The interconnection of RWH with the aquifer shows that fully penetrated exist about 35.8%, and remaining systems needs improvement. Adequacy of RWH exist revels that major portion of RWH system (about 70.4%) are constructed with proper recharging area. The inundation criteria about 52.8% of RWH structures recharge entire rainwater to the aquifer and scope for improvement is possible in many areas. The combined spatial distribution map shows that very good condition of implemented RWH system, exist for about 1/3rd of structures, 1/4th of them are in poor state and remaining fall in good category. Hence, improvement in RWH system must be carried at several parts of the study area to enhance the groundwater quantity and quality.