Improvement of Water Quality in Designed lakes through Integrated Rainwater Harvesting Strategies

In the South of India, designed lakes have been traditionally used to cater local water demands. These designed lakes though proved to be effective for subtropical climates got depilated due to the excessive development and use of ground water resources throughout India. With the gradual decline of ground water levels during the last decades, the Indian Water Policy 2002 called for more alternative sources, and hence the use of designed lakes became revived for various purposes in water supply. A government of Tamilnadu funded project provides model systems for rural drinking water supply based on the four IWRM principles. Before only few projects were derived from a comprehensive water resource strategy. Even fewer took account of other water uses in project areas. The emphasis was mainly on the productive use of water resources, with little attention paid to managing the resources themselves and to achieve suitable water quality. To meet the increasing challenges of water scarcity, pollution, and degradation of watersheds, catchment areas and ecosystems, water and related resources need to be managed in an integrated manner. The pilot set-up incorporates the complexity of a holistic approach and sophisticated water management taking into account that water scarcity is not a product of lack of water but water managemenf as such. Hence, a traditional water management. system (Oorani) was chosen, based on rainwater harvesting and it was verified by using common technologies of storage management, water treatment, run-off potentials and protection of catchments. A multibarrier system was introduced securing the water from pollution by providing a set of treatment steps treating rainwater run-off towards potable limits. As a result of this integrated approach a significant improvement of water quality in designed lakes could be achieved and has been monitored over a period of 1.5 years.